CA1092168A - Boron nitride-base superhard material and process for the production of same - Google Patents
Boron nitride-base superhard material and process for the production of sameInfo
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- CA1092168A CA1092168A CA266,758A CA266758A CA1092168A CA 1092168 A CA1092168 A CA 1092168A CA 266758 A CA266758 A CA 266758A CA 1092168 A CA1092168 A CA 1092168A
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- boron
- superhard material
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- aluminium
- nitride
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Abstract
BORON NITRIDE-BASE SUPERHARD MATERIALS
AND PROCESS FOR THE PRODUCTION OF SAME
ABSTRACT OF THE DISCLOSURE
The proposed superhard material is a solid solution of an element from the 3rd Group of the Periodic Table, which serves as an alloying agent, in boron nitride of a close-packed modification. The material of the invention is produced by exposing to a high temperature and pressure a feedstock mixture which comprises a source of boron and a source of nitrogen in a stoichiometric ratio, as well as an additive constituted by an element from the 3rd Group of the Periodic Table or borides thereof.
AND PROCESS FOR THE PRODUCTION OF SAME
ABSTRACT OF THE DISCLOSURE
The proposed superhard material is a solid solution of an element from the 3rd Group of the Periodic Table, which serves as an alloying agent, in boron nitride of a close-packed modification. The material of the invention is produced by exposing to a high temperature and pressure a feedstock mixture which comprises a source of boron and a source of nitrogen in a stoichiometric ratio, as well as an additive constituted by an element from the 3rd Group of the Periodic Table or borides thereof.
Description
L6~
The present invention relates to boron nitride-base superhard materials as well as to processes for the production of same.
Various kinds of superhard materials, such as cubic bo-ron nitride, man-made diamonds and the like, have gained wide popularity. Cubic boron nitride having a sphalerite-like struc-ture of lattice parameter 3,615 A is described in U.S. Patent ~o. 2,947,617, The cubic boron nitride lattice is composed of equal numbers of boron and nitrogen atoms, each boron atom being bonded with four nitrogen atoms disposed in space at the apices of the tetrahedron, and vice versa. Ihe space symmetry group of this cubic boron nitride is F = 43 m.
Cubic boron nitride approaches diamond in abrasive pro-perties and hardness and is far superior there~o in thermal stability. A great number of methods of production o~ cubic boron nitride is known. The most widespread process for the manufacture of cubic boron nitride involves high temperatures and pressures and uses a catalyst constituted by metals belong-ing to alkali- or alkali-earth groups and nitrides thereof (cm. U.~. Patent No. 2,947,617). The end product of this pro-cess, a mechanical mixture of cubic boron nitride and catalyst crystals, cannot be employed for manufacturing e.g. the busi-ness portion of cutting tools, since its mechanical strength is impaired by the alkali- or alkali-earth metals and nitrides thereof and, secondly, because the alkali- and alkali-earth metals combine with the ambient air, absorbing moisture there-from, with the resultant degradation of the compact product.
In some cases borides of alkali- and alkali-earth metals are - 3 ~
employed with a view to produeing a compact and molsture -resiætant product (c~. FrenGh Pate~t No. 27098,009). ~o the ~ame e~d, it is known in the art to produce cubic bo~on ~itri-de polycry~tals on the basi~ o~ variou~ binders (c~c U~
Pat~t ~o9~233,988). ~ the latter case,, in order to prod~ca a ¢ompa~t polycry~talline block, cubic boro~ nlt~id~ crgsta~
are to be manufactured fir~t and the~ bound together by use o~
a metallic or non-motallic bi~d~r9 agai~ at high pressures and temp~ra~ures. In all the ~oregoi~g proce~æes~ the binder~ are vastly in~erior to eu~ic boron ~itride in te~m~ of str~ngth a~d hard~e~, so that the ~t~en~th and integral hardnes~ of the compact product pr~pared from cubic boron nitride and t~e bindex are accordingly impaired.
~ long~ide catalgtic proces~ or the productio~ of cubic boroll ~itride~ it is likewi6e k~own i:~ the a;rt to emplo~
non-catalytic techrlique~3 Ior tha purpose (c~. U.S.Pat~nt No.
3,21~852 o~ Bund~ d CarladiaIl Patent No. 962,034 of ~IO~ iro--~a ar~d l~M~azuren}~)0 !l~he process according to U.S.Pa~e.nt ~oO 3,212,852 pro-d~ces a comps~ct pol~crystalline block of cubic boron nitride contalnîng ~o bi~ding agen~s, ~ith the consequ~nt gain in me~ha~cal 3trength ~d hs3~d~es5. Xowever, tho ~adva~t~5e of this proce6s consist~ in that it require6 high pressure v~-~ues ~P~ 10Q ]~B~ )9 causillg iIlten3ive wear of the proces~
equipment and raisi~; the manufacturi~g cost o~ the product.
~ h~ proc~s~ accordil:lg to the aanadi~n Pate2lt No.9~2,034 yie~ds a~ end product~ vi~.cubic boro~ nitride~ obtai~abl~
~ 6 at a pressure betw~e~ 60 and 90 kBar~ but in~erior to diamond in hardness and wear re~istance.
It is an object of the present inve~tion ~o provide a superhard material which wou~d be at ~east the aqual o~
cubic boron nitride in term~ o~ wear resistanc~ and hardne~, equivalent to cubic boron nitride in torm~ o~ th~rmal stabilitg~
and chemically inert towards ferrous metals and steels.
Furthe~more, said superhard material in a polycrystal~
compact ~~m should be free o~ unstable and moisture-sensitive compo~e~t~.
It is another object o~ the present in~ention to pro-vide a p~o~ for the production o~ a boron nitride-base su-p~rhard materia~ co~taining alloying additives, such as would en~ure ~ high yield o~ high-grade polycr~tzlline compact formation of said superhard material, requiring comparatively lo~ pressure and temperature parameters; i~ other words, to provide a~ effi¢ient and ~imple process.
~ he ~ora~oing an~ othar ob~ects are a~tain~d in a bor~n nltride-bas~ superhard material comp~ising allo~ing additive~, wher~in, in accorda~ce with the ~nvention, the alloyi~g;add~-tive is con~t~tuted by au olement from the 3~d Group of tho Periodic ~a~le capable o~ forming tetrahedr~l bond~, said suporhard matorial being formsd as a ~olid solution of ~aid element in a compaGt modi~ication of boron nitride of the following composition, atomic yO
- boron9 from 42 to 61 - ~itrogen, fxom 39 to 50 - allo~ing additive9 from 0.1 to 30 : - other impuritias, from 0401 to 2.
~9Z~
It is another object of the invention to provide a superhard material represented by à solid solu-tion in a close-packed modification of boron nitride of at least 0.1 atomic percent of an element from the 3rd-Group of the Periodic Table capable of forming tetrahedral bonds, the solid solution having the following composition, atomic %:
- boron, from about 42 to about 61 - nitrogen, from about 39 to about 50 o^l - 3rd-Group element from t~ to about 30 other impurities, from 0 to 2, provided the atomic % of said composition does not exceed 100.
It is another object of the invention to provide a process for the production of superhard material, which comprises preparing a feedstock mixture composed of a source of boron and a source of nitrogen, the boron and the nitrogen being in a stoichiometric ratio~ and an additive accounting for from l to 50 percent by weight of the mixture, the additive being constituted by at least one element from th2 3rd-Group of the Periodic Table capable of forming tetrahédral bonds, and exposing said feedstock mixture to a pressure of from about 50 to about 95 kBar and a temperature of from about 1,500 to about 3,000C.
a-_ 5 ~-~ he proposed superhard material of~ers the advantags o~ improved, sr at l~a~t equivalent, hardness and woar re~is-t~nce as again~t cubic boron nitride; inter alia9 it fea~ure~
improved, or at least equivalGnt , int~gral microhardness as co~pared with polycrystallin~ ¢ubic boron ~itrid~ thi~
case integral mic~ohard~ess shou~d be constru~ed as micro-hardne~s averaged ov~r tha entlre sur~ace area of a compact specime~ whîch repxesents a polycrystalline formation.Besides, the propo~ed ~up~rhard material is chemically inert toward~
~arrous mstals and steels and as thermally ~t~ble as cubic boron nitride~ ~urthermore, the proposed supe~hard material contains no componcnts which are hydrolysed and decompose in air; withstands prolonged storage without loss o~ its me-cha~ical prop~rties; exhibits e~c~llent cutting properties a~d can thus be success~ully emplo~ed in cutti~ tool~ such as cutters~mills, d'xill bits ~ld the like.
~ he proposed boron nitride~base superhard materia~ may be for~ed as a solid solution o~ boren in cubic boron nitride, a solid solution of alum~n~um i.n cubic boron nitride, or a m~ohanical mixture th~reo~. B~sidss, it m~y co~tai~
a ~olid ~olutio~ o~ nitroge~ in aluml~ium borides or ~ solid ~olutio~ of boron i~ aluminium nitride, an~ may r~pre~e~t, re~pectively, a solid solution o~ boron ln wurtzite~ e boron ~itride, a ~olid solutio~ of ~lumi~ium in wurt~te like boron nitride and mi~tures thareo~, a~ wsll a~ mechanical mixtuxes composed o~ solid solutio~s of boron in wurtzits-boron ~îtrid~, boron in aluminium nitride,~lumin1um in wurt-~2~6 zit~ boron nitride and other pha~es~
~ ha superhard material of this invention may ~e producedin a proce~s which comprise~ alloying additives such as elemen-tary boron and elemantary alumi~ium, either separatel~ or together, to a feedstock mi~ture co~tainin~ a source of boron and ~itrogen in a stoichiom~tric ratio B~.
The sources o~ boron a~d nitrogen i~ a stolchiometric r3tio B~ may be ~o~ituted by he~agonal and wurtzite boxon nitrideg taken either ~parately or together.
Be~ides9 boron-aluminium compounds, i.a. aluminium bo~i~es, may ba emp~oyed as the al~oying additive.
~ he proposed procesæ for the production o~ tho super-hard matarlal o~ this inve~tion o~fers the followlng adva~ta-ge9: (a) compact polycr~stals can be produced in a single--step reaation; (b) ths procsss can be co~ducted at re~ati-v~ly low P and ~ valuos, making it readily realizable at any plan~; (c) the e~d product is produced in a high percentag~
~ield; and (d) the product ~uperhard material may be mod1~ied, wi~hin certain limit~, a~ to hardnoss, plasticity9 brittle-ness / heat conductivity, ~ear resistance and other proper-~ies.
~ he invention will be sub~squent illustrated by exemplary embodime~t~ ther~o~.
I~ the course o~ experime~tation, use was made o~ both industrial;grade he~agonal boron nitride containing up to 0.2~o aluminium, up to 0.15% magnesium, up to 0.25~o iro~, up to 0015% calc~um and up to 0.5~0 carbon9 and he~ago~a~
~9 7 _ boron nitride ~ubjected to spacial treatment i~ hydrochloric acid and a mi~ure o~ ~u~phuric a~d nltric acids followed by washing and dr~ing~ ~he ha~agonal boron nitride priorl~
subjected to special che~ical treatme~t contained tha follow-in~ amounts o~ impuritles: al~minium, les~ than 0.001%; mag-nesium9 le~s than 0.001%; iron, less than 0.0005~0; and calcium9 less than 0~001%. ~or the purpose~ of commercial-sca~e pro-duction o~ the proposed superhard material, use should preferab~
ly be made ~f industrial-grade boron nitride~ since the special chemical treatme~t adversely affects the economics of th~
proc~s while tha impurities contained by indu~bria~-grad~
boron nitride in the ~ore~oi~g amounts have no e~fect what~o-ever on the mechanical propertie~ of the end product.
~ he eleme~tary aluminium and elementary bor~n emp~oyed as alloyin~ additives were of chemic~l purit~5 containing o~rar 99.5% o~ the host. ~he f~eds~ock compone~ were i:n the particle size xa~ge ~rom 5 to 100 micro~, pre;Eerably around 20 micro~s.
~ he pr~surs in th~ high-pressur0 chamber was d~teI~ ed b~ the jump~ in the el~ctric resista~ce o~ re~erence meta~ s at room t0mpera~ure; as~uming th~t the ~lectric r~sista~ce aump~ occurred at the followi~g pressure ~ralues in the cham-ber:
BiI II~ 25-4 !~Bar II III' 37 a:r BaII III. 59 ~Bar Bi~ , 89 S~, 113 to 115 l~ar.
8- ~9L0~2~
The temperature i~ the chamber wa~ determined by use of a platinum-pl~*inum-rhodium th~rmocouple as wel~ as by tha melting poi~ts of nickel9 plati~um, rhodium and molyb-denum under prsssurs.
boratory experimerlts and pilot-scale production o~ the proposed ~uperhard material used modified high-pr~s-~ure chambers o~ an an~ with-a-hole t~pe. Generally, it i~ possible to employ a~y type o~ apparatus capable o~ pro-viding a required pres~ure value, ebg. such as th~ one des-cribed in U~S.Patent ~o. 3~790,322, ~ebruary 5, 197~.
Should the proposed superhard material be produced on the ba~i~ o~ a feedstock mi~ture containing hexagonal modifi cations of ~oron nitride and eleme~tary boron, the material 15 a so~id solution of boron in cubic or wurtzite-~ike boron ~itride, or (~hould there be an excess of elemsntary boron in tho feedatock~ a mecha~ical mixture of solid solutions of boron in c~bic or wurt~it~-llke boron nitride and cubic ox wurtzite-lik~ boron nitrido in boron ~olid ~o~ution o~
nitrogen in boron)~ In th~ ~ormar case, whexe the superhard material is a solid solution of boron in cubic or wurtzite-e boro~ niliride, the ma~erial iB harder tha:EI cubic boronnitrid~ owing to the ~istortion3 occurring in the crystalline lattice OI boro~ nitride. Irl the latter case, where the super-hard material ilB a mechanical mix:ture of solid ~olutions of boron in bo~en nitride and nitrogen in boro~, the mate~
rial is likewise superior or equivalellt in hardness to cubic boron nitrlde. I~he leve~ of boron in the propo~ed supe~hæd 9 ~9Z~ ;8 material varie~ Irom 50.1 to 80 abomic percent7 nitrogen being the b~ ce~, ~he~ to:rted lattice parameter o~ the superhard il~aterial i~; about 3,620 A; th~ de~sitY ~rom 3-00 to 3~5 ~/cu.cm. In all cases the superhard ma~eria~ contai~s no compo~ents which are hydroli~3d ar~d decompose in a moist e~îrormant. Tho solid so~ution o~ nitrogen in boron; which makes up the propo~ed ~uperhard material i~ the ~econd above-described case, ma;~ haYe both a short-range and a long-rango order. A~ has been noted, the ~eedstock mixture ~or the pro-duE~tion o~ the propo~ed superh~rd material is pr~pared ~rom a hexagoxlal modi~i~a~io~ of boron nitride and amorphous or ¢rystalline boro}~, the level o~ elementary boron in the feed-stock mi~cture varying from 0.1 to 53 percen~ by weight, prefe-rabl;sr îrom 1 ~o 10 perce~t b~ weight. A~ter prepari~g the ~eed-stock mixture7 th~ latter is thoroughl;sr agitated u~til the compo~erLts are u~i~ormly distributed throu~h its bulk. Th~n the feed~ock mi:gture i~ mo~ded at a pressure from 5,000 to 10,0(30 kg/sq.cm. to produce a bi.llet. ~he starting billet thus produced is p~aced insid~ a pr~ssure--trallsmittirlg ~oxltai~r co}l~tructed from ~ithographic ~tone, pencil~o~e ~r aD~ othe~
material whi¢h becomes plRstic under high pressure, ~d e~uip-ped with a heat~r, whereupon the contai~er wlth the bi~let is placed in a high-pressure ch~mber ~sherci~ the billet is simul-~aneou~ly subjecte~ to high pressure a~d high temperature.
I~ t~e course o~ synthesis9 the he~agonal modificat~ons o~
boro~ ~itride are co~verted to c~ic boron ~itride, with boro~ being ~imulta~eously dissolved in ~ho ~orming cubio ~tructuxe. Xf the ~eed~tock mix*urs comprises wurtzite-~ike boron nitride, the latter can o~ly partially bo co~erted to cubic boro~ nitride. ~he synthesis pr~ssure ranges from 50 to 95 ~Bar, the temperature ~rom 1,500 to ~,000C. It is preferred tha~ the synthesis be carried out in the pressure range from 65 to 85 kBar a~d in the temperature range from 19800 to 2,400C~ ~he s~theæis time varies from 5 ~0cond~
to over 3 minutes, d~pe~ding on the specific pressure and temperature va~ues employed in each concrete case.
Should the ~eed~tock mixture comprise hexa~o~al modifi~a-tions of boron nitride and aluminium, the superhard materi-al is a solid solution o~ aluminium in cubic or wurtzite~like boron ~itride. If the level o~ a~mi~ium in the ~eedstoc~
mix*ure iB a~ou~t or exceeds 5 percent by weight, the superhard material i~ a mechanical mix*ure of mutual solid solutions o~
cubic or wurtzite-lika boron ni-tride and aluminium nitride (boron in aluminium ~itride). ~s in the case of the solid ~olution o~ boron in cubic boro~ nitride, the solid solutio~
of aluminium in cubic or wurt~ite-like boron nitrido is supe-rior to cubic boron ~itride in terms of hardnes~. However~
~inoe th~ a~um m ium atom has a ~reater num~er of electrons than a boron a~om, the bonds formed therebg are not so ri~idly orie~ted as those formed by the allo~ing additiva boron~
E'or this reason, the superhard materlal ~ormed aæ a solid ~olution of a~uminium in cubic boron ~itride is more shock-resistant, more "pla~tic", to the extent this tsrm is app~i-cable hereO~he lattice parameter of the solid solutio~ o~
alumi~ium i~ cubi~ boron nitrid~ is about 39610 A~ I~ the ~19Z~6~
Ieed~tock mix~ure contain~ more aluminiumt about or i~ exces~
o~ 5 percent by weight, the supe~hard material is a mechan;ca~
mixture o~ mutual ~olid solution of cubic or wurtzite-like b~ro~l nitride a~d a~uminium rlitride. ~he latter'.s ~ohRI hard-es~ i9 9. ~s boron is being di~olved therein, the hardrless of alum~nium nitride progressively ri~es to approach that of cubic boron r~itride. Sor the in~egral hard~ess o~ pol~¢ryE;-talli~e superhard material i9 likewise high enough. Th3 to~al guantity of alumi:llium oo~tained by the superhard materia~
rar~es ~rom ~04 to U atomic perc~nt. In this ca~e the den-~ity o~ the superhard pol~cr;srstal~ J.ie~ in the range from 3~,20 to 3.52 g~u~cm~ In bot~ ca~es, the suparhard materia~
i5 stable in a ~oist enYiro~m0~t, feature~ e~celle~ hardness a~d wear re~i~ta~ce, e~hibits good cutti~g prope~ties arld pro~ applicab~e ~r cutti~g ¢aRt iro~ and highly qu~nched s1;eel~, ~ 5 hal3 been obsorYed, the abo~e-describ0d superhard mal~erial is produced ~rom a fe~dstock mixture ~ompris:~g he~gonal moai~icatio~ of boron ~itrlde and ~lems~ta3~sr a~u-mi:llium, th0 level of ~lumi~ium in thc mixtura var~ g from 0.1 to 30 percs~t by weight and more. A:Eter the ~eed~tock mixture has been propared, it is thoroughly agitated, mo~ded at a pre~sure ~rom 5,000 to 10,000 kgJsq.cmO i~o a billet, and the bi~let i8 placed in à high-pr~ssur~ chamber whexei it i~ ~imu~-ta~aously exposed to a pressuxe of from 50 to 95 kBar and a temperature of Irom 1,500 to 3tO00C. ~he combi~ed effect of high pressure and tem~erature on the billet compris-~ 6 it~ hsxagonal modifications o~ boron nitride and aluminium causes the he~agonal modi~ications of boron nitride to be co~verted to a cubic modification, the alumi~ium being ~imul-taneously dissolved therein. ~he nitrogen atom~ substituted by aluminium ~'oxm aluminium nitrid~, boron bei~g simultane-ousIy dissolved i~ the aluminium nitride.
~ he preferred content o~ alumi~ium in the ~eedstock mix-ture is from 2 to 8 psrcent by weigh~; the preferred synt-hesis co~dition~are 60 to 85 kBar of pressure and 1,800 to 2,400C~
o~ temperature.
In certain cas~s the superhard material is pre~erab~
composed of two, rather tha~ one, types o~ solid solutio~, e.,g. a solid solutio~ of boron in cubic boroll nitride and a solid solution of aluminium i~ cubic boron llitrido. In such a ca~e, the starti~g mi~ture for the production o~ the propo-sed superhard material is mado up o~ hexagonal modi~ications of boron nitride as well as o~' aluminium and boron which are add0d to tho mixture a~ the same time. ~he end produc~ mar~ufac-tured ~rom the fore~o~ng type of initial mi~ture may contain alumi~ium borides alorlgside the above-descr~bed pha~es.~he s~nthesi~ o~ the suporhard material ~rom initial miæture con-taining hexagonal modi~ica~io~s of boron ~itrid~boro~ a~d alumi~ium is carried out at the same pressure a~d ~emper~ure values, but the syntheæis time iæ ge~erall~ sho~ter.
Be~ides elementary boron and aluminium, th~ al~oyi~g additive may like~i~e be conætituted by boron-aluminium co~-pound~, viz.a}umirLLum borides such as ~B2 or AlB12.I~ such ~ Z ~ 6 8 a case ~t i~ easier to prepare the i~itlal mix*ure whi¢h i~
to in~luda he~agonal modifications o~ boron ~itride, ~oro~
and aluminium at the ~ame time4 ~he oontent of borides i~
the initial mixtura may reach 20 to 30 percent by weight a~d even highar, and tha borides may be added to the mixture either ~eparately or to~ther. ~he feedstock mixture is trea-ted at ~ presæure in the range from about 50 to about 95 kBar and a t~mperature in the ra~ge ~rom about 1,500 to about 3,000~.", the preferred pres~ure and temperature ra~
bei~g ~rom 65 to 80 l~ d from 1,900 to 2,500~C., respec-tively~
~ ho level of borides ln the ~eed~tock mixture is pre-~erably in the rango ~rom 2 to 10 percent by weigh~.
The æuperhard materiai produced in th~ synthesis i~
co~stitut~d by so~d solutions o:E aluminium boride~ i~ cubic boroxl ~tride (boro~ and aluminium in cubic boron nitride) 0r by a mecha~ical mi3~ture o~ mutual so~id solutions o~
alumixlium borides a~d cubic boron nitride (a mechaxlioal mi~
bur~ ~oxmed by solid solutions oi~ boro~ a}l~ alumiilLm in cubic boron nitride a~d a solid solution of nitrogen or boro~ in aluminium boride3). Should a wurtzite~ e modi~
c~ion of bo~on }lit~de be employed as boron aIld nitrogen ~ourcaS it i~ possible to obt~in, {~;ivon appropria~e synbh~-~i3 conditio~s, a superha:rd ma~erisl compri~i~g a ~olid solu-~ion OI aluminium borides in wur~zite-like boron nitride or a mixtura of mutual solid solutions of aluminlum borid~
and wurtzibe-l~ke boro~ ~itrido. In some case~9 tho material ~z~
may additionally contai~ an alum~nium nitride-base phase.
As noted above, in all cascs both hexagona~ boron nitride and wurt~ite boron nitride may be employ~d for pre-pariDg the feedstock mixtur~. It is furthar pos~ible to employ both modifica~ions simultaneouslyg Wurthæite-lik~ boro~ nitride is adva~tageouæ in th~t (a) i~ is characterized by an abundance of lattice distor tion~ of various typss, inter alia, a great cone~ntration of linear and point defactæ, and a great co~cen~ra~ion o~
la~t~ce defects woa~en i~t3ratom~c bo~d~, promoting the ~o~-mation of solid ~olutlons upon sy~thesis; (b) while being converted to a cubic structuro, wurtzito-like boron nitride i~crcases in volum~, making up ~or the volume reductio~ ob~
~orved in t~ conversion of graphite-~ike boron nitride to a cubic structure and ~hexeby conducin~ to compact pol~-cr~stalline formation~ cau~i~g no sub~tan~ial change of ~hape of th~ ori~inal billet.
Be~ido~ it i~ de~irable in al~ ca~es to ~trip th~ ori-ginal bi~let frvm moi~tur~, e.g. b~ drying.
~ he i~vention will be ~urther understood from the followin~ e~emplary embodimcnt~ thereof il~ustrating th~
propo~ed process for the production of ~uperhard ma~erial.
x a m p ~ e ~ he feed~tock mixture is prepared from 99 perce~t by weight o~ he~agonal boron nltxide and 1 percent by w~ight o~
eleme~tary aluminium. ~he particl~ si~e of t~ he~ago~al boron nitride is`less tha~ 10~ mi~ro~; that o~ tho alumi-3Z~i8 nium is o~ the order of 20 micro~ he mixture 1~ thoIoughlyagitat0d a~d mouldedt at a pr~sure of from 5,000 to 10,000 kg)~q~cm. i~to a bille-t o~ den0ity 2.11 g/c~l.cm. which i~ dried a~d then placed in a hi~h-pre~ure chamb~r. ~he pressure i~
the chamb~r is built up to 60 kBar and the tsmpera~ure to
The present invention relates to boron nitride-base superhard materials as well as to processes for the production of same.
Various kinds of superhard materials, such as cubic bo-ron nitride, man-made diamonds and the like, have gained wide popularity. Cubic boron nitride having a sphalerite-like struc-ture of lattice parameter 3,615 A is described in U.S. Patent ~o. 2,947,617, The cubic boron nitride lattice is composed of equal numbers of boron and nitrogen atoms, each boron atom being bonded with four nitrogen atoms disposed in space at the apices of the tetrahedron, and vice versa. Ihe space symmetry group of this cubic boron nitride is F = 43 m.
Cubic boron nitride approaches diamond in abrasive pro-perties and hardness and is far superior there~o in thermal stability. A great number of methods of production o~ cubic boron nitride is known. The most widespread process for the manufacture of cubic boron nitride involves high temperatures and pressures and uses a catalyst constituted by metals belong-ing to alkali- or alkali-earth groups and nitrides thereof (cm. U.~. Patent No. 2,947,617). The end product of this pro-cess, a mechanical mixture of cubic boron nitride and catalyst crystals, cannot be employed for manufacturing e.g. the busi-ness portion of cutting tools, since its mechanical strength is impaired by the alkali- or alkali-earth metals and nitrides thereof and, secondly, because the alkali- and alkali-earth metals combine with the ambient air, absorbing moisture there-from, with the resultant degradation of the compact product.
In some cases borides of alkali- and alkali-earth metals are - 3 ~
employed with a view to produeing a compact and molsture -resiætant product (c~. FrenGh Pate~t No. 27098,009). ~o the ~ame e~d, it is known in the art to produce cubic bo~on ~itri-de polycry~tals on the basi~ o~ variou~ binders (c~c U~
Pat~t ~o9~233,988). ~ the latter case,, in order to prod~ca a ¢ompa~t polycry~talline block, cubic boro~ nlt~id~ crgsta~
are to be manufactured fir~t and the~ bound together by use o~
a metallic or non-motallic bi~d~r9 agai~ at high pressures and temp~ra~ures. In all the ~oregoi~g proce~æes~ the binder~ are vastly in~erior to eu~ic boron ~itride in te~m~ of str~ngth a~d hard~e~, so that the ~t~en~th and integral hardnes~ of the compact product pr~pared from cubic boron nitride and t~e bindex are accordingly impaired.
~ long~ide catalgtic proces~ or the productio~ of cubic boroll ~itride~ it is likewi6e k~own i:~ the a;rt to emplo~
non-catalytic techrlique~3 Ior tha purpose (c~. U.S.Pat~nt No.
3,21~852 o~ Bund~ d CarladiaIl Patent No. 962,034 of ~IO~ iro--~a ar~d l~M~azuren}~)0 !l~he process according to U.S.Pa~e.nt ~oO 3,212,852 pro-d~ces a comps~ct pol~crystalline block of cubic boron nitride contalnîng ~o bi~ding agen~s, ~ith the consequ~nt gain in me~ha~cal 3trength ~d hs3~d~es5. Xowever, tho ~adva~t~5e of this proce6s consist~ in that it require6 high pressure v~-~ues ~P~ 10Q ]~B~ )9 causillg iIlten3ive wear of the proces~
equipment and raisi~; the manufacturi~g cost o~ the product.
~ h~ proc~s~ accordil:lg to the aanadi~n Pate2lt No.9~2,034 yie~ds a~ end product~ vi~.cubic boro~ nitride~ obtai~abl~
~ 6 at a pressure betw~e~ 60 and 90 kBar~ but in~erior to diamond in hardness and wear re~istance.
It is an object of the present inve~tion ~o provide a superhard material which wou~d be at ~east the aqual o~
cubic boron nitride in term~ o~ wear resistanc~ and hardne~, equivalent to cubic boron nitride in torm~ o~ th~rmal stabilitg~
and chemically inert towards ferrous metals and steels.
Furthe~more, said superhard material in a polycrystal~
compact ~~m should be free o~ unstable and moisture-sensitive compo~e~t~.
It is another object o~ the present in~ention to pro-vide a p~o~ for the production o~ a boron nitride-base su-p~rhard materia~ co~taining alloying additives, such as would en~ure ~ high yield o~ high-grade polycr~tzlline compact formation of said superhard material, requiring comparatively lo~ pressure and temperature parameters; i~ other words, to provide a~ effi¢ient and ~imple process.
~ he ~ora~oing an~ othar ob~ects are a~tain~d in a bor~n nltride-bas~ superhard material comp~ising allo~ing additive~, wher~in, in accorda~ce with the ~nvention, the alloyi~g;add~-tive is con~t~tuted by au olement from the 3~d Group of tho Periodic ~a~le capable o~ forming tetrahedr~l bond~, said suporhard matorial being formsd as a ~olid solution of ~aid element in a compaGt modi~ication of boron nitride of the following composition, atomic yO
- boron9 from 42 to 61 - ~itrogen, fxom 39 to 50 - allo~ing additive9 from 0.1 to 30 : - other impuritias, from 0401 to 2.
~9Z~
It is another object of the invention to provide a superhard material represented by à solid solu-tion in a close-packed modification of boron nitride of at least 0.1 atomic percent of an element from the 3rd-Group of the Periodic Table capable of forming tetrahedral bonds, the solid solution having the following composition, atomic %:
- boron, from about 42 to about 61 - nitrogen, from about 39 to about 50 o^l - 3rd-Group element from t~ to about 30 other impurities, from 0 to 2, provided the atomic % of said composition does not exceed 100.
It is another object of the invention to provide a process for the production of superhard material, which comprises preparing a feedstock mixture composed of a source of boron and a source of nitrogen, the boron and the nitrogen being in a stoichiometric ratio~ and an additive accounting for from l to 50 percent by weight of the mixture, the additive being constituted by at least one element from th2 3rd-Group of the Periodic Table capable of forming tetrahédral bonds, and exposing said feedstock mixture to a pressure of from about 50 to about 95 kBar and a temperature of from about 1,500 to about 3,000C.
a-_ 5 ~-~ he proposed superhard material of~ers the advantags o~ improved, sr at l~a~t equivalent, hardness and woar re~is-t~nce as again~t cubic boron nitride; inter alia9 it fea~ure~
improved, or at least equivalGnt , int~gral microhardness as co~pared with polycrystallin~ ¢ubic boron ~itrid~ thi~
case integral mic~ohard~ess shou~d be constru~ed as micro-hardne~s averaged ov~r tha entlre sur~ace area of a compact specime~ whîch repxesents a polycrystalline formation.Besides, the propo~ed ~up~rhard material is chemically inert toward~
~arrous mstals and steels and as thermally ~t~ble as cubic boron nitride~ ~urthermore, the proposed supe~hard material contains no componcnts which are hydrolysed and decompose in air; withstands prolonged storage without loss o~ its me-cha~ical prop~rties; exhibits e~c~llent cutting properties a~d can thus be success~ully emplo~ed in cutti~ tool~ such as cutters~mills, d'xill bits ~ld the like.
~ he proposed boron nitride~base superhard materia~ may be for~ed as a solid solution o~ boren in cubic boron nitride, a solid solution of alum~n~um i.n cubic boron nitride, or a m~ohanical mixture th~reo~. B~sidss, it m~y co~tai~
a ~olid ~olutio~ o~ nitroge~ in aluml~ium borides or ~ solid ~olutio~ of boron i~ aluminium nitride, an~ may r~pre~e~t, re~pectively, a solid solution o~ boron ln wurtzite~ e boron ~itride, a ~olid solutio~ of ~lumi~ium in wurt~te like boron nitride and mi~tures thareo~, a~ wsll a~ mechanical mixtuxes composed o~ solid solutio~s of boron in wurtzits-boron ~îtrid~, boron in aluminium nitride,~lumin1um in wurt-~2~6 zit~ boron nitride and other pha~es~
~ ha superhard material of this invention may ~e producedin a proce~s which comprise~ alloying additives such as elemen-tary boron and elemantary alumi~ium, either separatel~ or together, to a feedstock mi~ture co~tainin~ a source of boron and ~itrogen in a stoichiom~tric ratio B~.
The sources o~ boron a~d nitrogen i~ a stolchiometric r3tio B~ may be ~o~ituted by he~agonal and wurtzite boxon nitrideg taken either ~parately or together.
Be~ides9 boron-aluminium compounds, i.a. aluminium bo~i~es, may ba emp~oyed as the al~oying additive.
~ he proposed procesæ for the production o~ tho super-hard matarlal o~ this inve~tion o~fers the followlng adva~ta-ge9: (a) compact polycr~stals can be produced in a single--step reaation; (b) ths procsss can be co~ducted at re~ati-v~ly low P and ~ valuos, making it readily realizable at any plan~; (c) the e~d product is produced in a high percentag~
~ield; and (d) the product ~uperhard material may be mod1~ied, wi~hin certain limit~, a~ to hardnoss, plasticity9 brittle-ness / heat conductivity, ~ear resistance and other proper-~ies.
~ he invention will be sub~squent illustrated by exemplary embodime~t~ ther~o~.
I~ the course o~ experime~tation, use was made o~ both industrial;grade he~agonal boron nitride containing up to 0.2~o aluminium, up to 0.15% magnesium, up to 0.25~o iro~, up to 0015% calc~um and up to 0.5~0 carbon9 and he~ago~a~
~9 7 _ boron nitride ~ubjected to spacial treatment i~ hydrochloric acid and a mi~ure o~ ~u~phuric a~d nltric acids followed by washing and dr~ing~ ~he ha~agonal boron nitride priorl~
subjected to special che~ical treatme~t contained tha follow-in~ amounts o~ impuritles: al~minium, les~ than 0.001%; mag-nesium9 le~s than 0.001%; iron, less than 0.0005~0; and calcium9 less than 0~001%. ~or the purpose~ of commercial-sca~e pro-duction o~ the proposed superhard material, use should preferab~
ly be made ~f industrial-grade boron nitride~ since the special chemical treatme~t adversely affects the economics of th~
proc~s while tha impurities contained by indu~bria~-grad~
boron nitride in the ~ore~oi~g amounts have no e~fect what~o-ever on the mechanical propertie~ of the end product.
~ he eleme~tary aluminium and elementary bor~n emp~oyed as alloyin~ additives were of chemic~l purit~5 containing o~rar 99.5% o~ the host. ~he f~eds~ock compone~ were i:n the particle size xa~ge ~rom 5 to 100 micro~, pre;Eerably around 20 micro~s.
~ he pr~surs in th~ high-pressur0 chamber was d~teI~ ed b~ the jump~ in the el~ctric resista~ce o~ re~erence meta~ s at room t0mpera~ure; as~uming th~t the ~lectric r~sista~ce aump~ occurred at the followi~g pressure ~ralues in the cham-ber:
BiI II~ 25-4 !~Bar II III' 37 a:r BaII III. 59 ~Bar Bi~ , 89 S~, 113 to 115 l~ar.
8- ~9L0~2~
The temperature i~ the chamber wa~ determined by use of a platinum-pl~*inum-rhodium th~rmocouple as wel~ as by tha melting poi~ts of nickel9 plati~um, rhodium and molyb-denum under prsssurs.
boratory experimerlts and pilot-scale production o~ the proposed ~uperhard material used modified high-pr~s-~ure chambers o~ an an~ with-a-hole t~pe. Generally, it i~ possible to employ a~y type o~ apparatus capable o~ pro-viding a required pres~ure value, ebg. such as th~ one des-cribed in U~S.Patent ~o. 3~790,322, ~ebruary 5, 197~.
Should the proposed superhard material be produced on the ba~i~ o~ a feedstock mi~ture containing hexagonal modifi cations of ~oron nitride and eleme~tary boron, the material 15 a so~id solution of boron in cubic or wurtzite-~ike boron ~itride, or (~hould there be an excess of elemsntary boron in tho feedatock~ a mecha~ical mixture of solid solutions of boron in c~bic or wurt~it~-llke boron nitride and cubic ox wurtzite-lik~ boron nitrido in boron ~olid ~o~ution o~
nitrogen in boron)~ In th~ ~ormar case, whexe the superhard material is a solid solution of boron in cubic or wurtzite-e boro~ niliride, the ma~erial iB harder tha:EI cubic boronnitrid~ owing to the ~istortion3 occurring in the crystalline lattice OI boro~ nitride. Irl the latter case, where the super-hard material ilB a mechanical mix:ture of solid ~olutions of boron in bo~en nitride and nitrogen in boro~, the mate~
rial is likewise superior or equivalellt in hardness to cubic boron nitrlde. I~he leve~ of boron in the propo~ed supe~hæd 9 ~9Z~ ;8 material varie~ Irom 50.1 to 80 abomic percent7 nitrogen being the b~ ce~, ~he~ to:rted lattice parameter o~ the superhard il~aterial i~; about 3,620 A; th~ de~sitY ~rom 3-00 to 3~5 ~/cu.cm. In all cases the superhard ma~eria~ contai~s no compo~ents which are hydroli~3d ar~d decompose in a moist e~îrormant. Tho solid so~ution o~ nitrogen in boron; which makes up the propo~ed ~uperhard material i~ the ~econd above-described case, ma;~ haYe both a short-range and a long-rango order. A~ has been noted, the ~eedstock mixture ~or the pro-duE~tion o~ the propo~ed superh~rd material is pr~pared ~rom a hexagoxlal modi~i~a~io~ of boron nitride and amorphous or ¢rystalline boro}~, the level o~ elementary boron in the feed-stock mi~cture varying from 0.1 to 53 percen~ by weight, prefe-rabl;sr îrom 1 ~o 10 perce~t b~ weight. A~ter prepari~g the ~eed-stock mixture7 th~ latter is thoroughl;sr agitated u~til the compo~erLts are u~i~ormly distributed throu~h its bulk. Th~n the feed~ock mi:gture i~ mo~ded at a pressure from 5,000 to 10,0(30 kg/sq.cm. to produce a bi.llet. ~he starting billet thus produced is p~aced insid~ a pr~ssure--trallsmittirlg ~oxltai~r co}l~tructed from ~ithographic ~tone, pencil~o~e ~r aD~ othe~
material whi¢h becomes plRstic under high pressure, ~d e~uip-ped with a heat~r, whereupon the contai~er wlth the bi~let is placed in a high-pressure ch~mber ~sherci~ the billet is simul-~aneou~ly subjecte~ to high pressure a~d high temperature.
I~ t~e course o~ synthesis9 the he~agonal modificat~ons o~
boro~ ~itride are co~verted to c~ic boron ~itride, with boro~ being ~imulta~eously dissolved in ~ho ~orming cubio ~tructuxe. Xf the ~eed~tock mix*urs comprises wurtzite-~ike boron nitride, the latter can o~ly partially bo co~erted to cubic boro~ nitride. ~he synthesis pr~ssure ranges from 50 to 95 ~Bar, the temperature ~rom 1,500 to ~,000C. It is preferred tha~ the synthesis be carried out in the pressure range from 65 to 85 kBar a~d in the temperature range from 19800 to 2,400C~ ~he s~theæis time varies from 5 ~0cond~
to over 3 minutes, d~pe~ding on the specific pressure and temperature va~ues employed in each concrete case.
Should the ~eed~tock mixture comprise hexa~o~al modifi~a-tions of boron nitride and aluminium, the superhard materi-al is a solid solution o~ aluminium in cubic or wurtzite~like boron ~itride. If the level o~ a~mi~ium in the ~eedstoc~
mix*ure iB a~ou~t or exceeds 5 percent by weight, the superhard material i~ a mechanical mix*ure of mutual solid solutions o~
cubic or wurtzite-lika boron ni-tride and aluminium nitride (boron in aluminium ~itride). ~s in the case of the solid ~olution o~ boron in cubic boro~ nitride, the solid solutio~
of aluminium in cubic or wurt~ite-like boron nitrido is supe-rior to cubic boron ~itride in terms of hardnes~. However~
~inoe th~ a~um m ium atom has a ~reater num~er of electrons than a boron a~om, the bonds formed therebg are not so ri~idly orie~ted as those formed by the allo~ing additiva boron~
E'or this reason, the superhard materlal ~ormed aæ a solid ~olution of a~uminium in cubic boron ~itride is more shock-resistant, more "pla~tic", to the extent this tsrm is app~i-cable hereO~he lattice parameter of the solid solutio~ o~
alumi~ium i~ cubi~ boron nitrid~ is about 39610 A~ I~ the ~19Z~6~
Ieed~tock mix~ure contain~ more aluminiumt about or i~ exces~
o~ 5 percent by weight, the supe~hard material is a mechan;ca~
mixture o~ mutual ~olid solution of cubic or wurtzite-like b~ro~l nitride a~d a~uminium rlitride. ~he latter'.s ~ohRI hard-es~ i9 9. ~s boron is being di~olved therein, the hardrless of alum~nium nitride progressively ri~es to approach that of cubic boron r~itride. Sor the in~egral hard~ess o~ pol~¢ryE;-talli~e superhard material i9 likewise high enough. Th3 to~al guantity of alumi:llium oo~tained by the superhard materia~
rar~es ~rom ~04 to U atomic perc~nt. In this ca~e the den-~ity o~ the superhard pol~cr;srstal~ J.ie~ in the range from 3~,20 to 3.52 g~u~cm~ In bot~ ca~es, the suparhard materia~
i5 stable in a ~oist enYiro~m0~t, feature~ e~celle~ hardness a~d wear re~i~ta~ce, e~hibits good cutti~g prope~ties arld pro~ applicab~e ~r cutti~g ¢aRt iro~ and highly qu~nched s1;eel~, ~ 5 hal3 been obsorYed, the abo~e-describ0d superhard mal~erial is produced ~rom a fe~dstock mixture ~ompris:~g he~gonal moai~icatio~ of boron ~itrlde and ~lems~ta3~sr a~u-mi:llium, th0 level of ~lumi~ium in thc mixtura var~ g from 0.1 to 30 percs~t by weight and more. A:Eter the ~eed~tock mixture has been propared, it is thoroughly agitated, mo~ded at a pre~sure ~rom 5,000 to 10,000 kgJsq.cmO i~o a billet, and the bi~let i8 placed in à high-pr~ssur~ chamber whexei it i~ ~imu~-ta~aously exposed to a pressuxe of from 50 to 95 kBar and a temperature of Irom 1,500 to 3tO00C. ~he combi~ed effect of high pressure and tem~erature on the billet compris-~ 6 it~ hsxagonal modifications o~ boron nitride and aluminium causes the he~agonal modi~ications of boron nitride to be co~verted to a cubic modification, the alumi~ium being ~imul-taneously dissolved therein. ~he nitrogen atom~ substituted by aluminium ~'oxm aluminium nitrid~, boron bei~g simultane-ousIy dissolved i~ the aluminium nitride.
~ he preferred content o~ alumi~ium in the ~eedstock mix-ture is from 2 to 8 psrcent by weigh~; the preferred synt-hesis co~dition~are 60 to 85 kBar of pressure and 1,800 to 2,400C~
o~ temperature.
In certain cas~s the superhard material is pre~erab~
composed of two, rather tha~ one, types o~ solid solutio~, e.,g. a solid solutio~ of boron in cubic boroll nitride and a solid solution of aluminium i~ cubic boron llitrido. In such a ca~e, the starti~g mi~ture for the production o~ the propo-sed superhard material is mado up o~ hexagonal modi~ications of boron nitride as well as o~' aluminium and boron which are add0d to tho mixture a~ the same time. ~he end produc~ mar~ufac-tured ~rom the fore~o~ng type of initial mi~ture may contain alumi~ium borides alorlgside the above-descr~bed pha~es.~he s~nthesi~ o~ the suporhard material ~rom initial miæture con-taining hexagonal modi~ica~io~s of boron ~itrid~boro~ a~d alumi~ium is carried out at the same pressure a~d ~emper~ure values, but the syntheæis time iæ ge~erall~ sho~ter.
Be~ides elementary boron and aluminium, th~ al~oyi~g additive may like~i~e be conætituted by boron-aluminium co~-pound~, viz.a}umirLLum borides such as ~B2 or AlB12.I~ such ~ Z ~ 6 8 a case ~t i~ easier to prepare the i~itlal mix*ure whi¢h i~
to in~luda he~agonal modifications o~ boron ~itride, ~oro~
and aluminium at the ~ame time4 ~he oontent of borides i~
the initial mixtura may reach 20 to 30 percent by weight a~d even highar, and tha borides may be added to the mixture either ~eparately or to~ther. ~he feedstock mixture is trea-ted at ~ presæure in the range from about 50 to about 95 kBar and a t~mperature in the ra~ge ~rom about 1,500 to about 3,000~.", the preferred pres~ure and temperature ra~
bei~g ~rom 65 to 80 l~ d from 1,900 to 2,500~C., respec-tively~
~ ho level of borides ln the ~eed~tock mixture is pre-~erably in the rango ~rom 2 to 10 percent by weigh~.
The æuperhard materiai produced in th~ synthesis i~
co~stitut~d by so~d solutions o:E aluminium boride~ i~ cubic boroxl ~tride (boro~ and aluminium in cubic boron nitride) 0r by a mecha~ical mi3~ture o~ mutual so~id solutions o~
alumixlium borides a~d cubic boron nitride (a mechaxlioal mi~
bur~ ~oxmed by solid solutions oi~ boro~ a}l~ alumiilLm in cubic boron nitride a~d a solid solution of nitrogen or boro~ in aluminium boride3). Should a wurtzite~ e modi~
c~ion of bo~on }lit~de be employed as boron aIld nitrogen ~ourcaS it i~ possible to obt~in, {~;ivon appropria~e synbh~-~i3 conditio~s, a superha:rd ma~erisl compri~i~g a ~olid solu-~ion OI aluminium borides in wur~zite-like boron nitride or a mixtura of mutual solid solutions of aluminlum borid~
and wurtzibe-l~ke boro~ ~itrido. In some case~9 tho material ~z~
may additionally contai~ an alum~nium nitride-base phase.
As noted above, in all cascs both hexagona~ boron nitride and wurt~ite boron nitride may be employ~d for pre-pariDg the feedstock mixtur~. It is furthar pos~ible to employ both modifica~ions simultaneouslyg Wurthæite-lik~ boro~ nitride is adva~tageouæ in th~t (a) i~ is characterized by an abundance of lattice distor tion~ of various typss, inter alia, a great cone~ntration of linear and point defactæ, and a great co~cen~ra~ion o~
la~t~ce defects woa~en i~t3ratom~c bo~d~, promoting the ~o~-mation of solid ~olutlons upon sy~thesis; (b) while being converted to a cubic structuro, wurtzito-like boron nitride i~crcases in volum~, making up ~or the volume reductio~ ob~
~orved in t~ conversion of graphite-~ike boron nitride to a cubic structure and ~hexeby conducin~ to compact pol~-cr~stalline formation~ cau~i~g no sub~tan~ial change of ~hape of th~ ori~inal billet.
Be~ido~ it i~ de~irable in al~ ca~es to ~trip th~ ori-ginal bi~let frvm moi~tur~, e.g. b~ drying.
~ he i~vention will be ~urther understood from the followin~ e~emplary embodimcnt~ thereof il~ustrating th~
propo~ed process for the production of ~uperhard ma~erial.
x a m p ~ e ~ he feed~tock mixture is prepared from 99 perce~t by weight o~ he~agonal boron nltxide and 1 percent by w~ight o~
eleme~tary aluminium. ~he particl~ si~e of t~ he~ago~al boron nitride is`less tha~ 10~ mi~ro~; that o~ tho alumi-3Z~i8 nium is o~ the order of 20 micro~ he mixture 1~ thoIoughlyagitat0d a~d mouldedt at a pr~sure of from 5,000 to 10,000 kg)~q~cm. i~to a bille-t o~ den0ity 2.11 g/c~l.cm. which i~ dried a~d then placed in a hi~h-pre~ure chamb~r. ~he pressure i~
the chamb~r is built up to 60 kBar and the tsmpera~ure to
2,000C., ~aid sy~thesis co~ditions being maintained for 1 minute~ ~hen the he~*2r i~ cut off, the pressure is decreased to the atmo~pheriG le~el, and the end product, a solid solu-tio~ o~ aluminium in cubic boro~ nitride, containing 0.~6 a~.%
o~ , 49.76 at~% of boron, ~9.76 at.~ o~ nitrogen, and impuritie~ - the bala~ce, is withdra~n from the chamber. ~he density of the product polycr~tal is 3.46 g~cu~cm. ~he la~ti-ee parameter o~ th~ cubic phase is 3961~ ~.
E x a m p ~ e 2 The starting miYture compri~e~ 95 percent by weight o~
hexagonal boron ~itride and 5 perce~t by weigh~ of elemen-tary a~uminium. The density o~ t:he moldod billet iB 2.20 g/cu~cm. SubjeGting the billet to a pres~ure o~ 7~ kBar and a temperature of 29100C. for 30 seconds yields a mono-lithic polycr~stalline block made up o~ a solid so~utio~ .
ef aluminium in cublc boro~ DitrideJ the billet being mol-ded in a procedure dup~ica~i~g tha~ o~ ~xamp~e 1. ~-ray phasc-sh~ ahaly~is ~e~eals traces o~ an alumi ~ um nitride-~ase phase. F~he d6n~ity o~ the pol~cry~tal i~ 3042 g/cu.cm.
The lattice parameter of the cubic pha~e i8 about 3,610~.
F~h~ spe~ime~ co~tains 2.36 at,.% o:e alumi~ium, 48.80 at.% of boxont 48.80 a~.% OI nitroge~,the balance bei~ impuritie3.
E x a m p ~ o 3 ~ he starting mi~*ure compri~cs 80 percent by wei~ht of he2:agonal boron llitride, 10 percsnt by w0ight of wurt-zite b~ro~ nitride a~d 10 perce~t by weight of elementary alumi ni~m~ æhe billet of den~ity 2.30 g/cu~cm. molded in a pro-cedure duplicating that of Example 1, i5 subaected to a p~es~ure o~ 85 kBar a~d a t~mper~ture of 2,~00C. for 15 ~e-conds. ~he monolithi¢ polycrysta~line block thu~ producod i~
constituted b~ a mech~ical mixture of mutual ~olid solu-tion~ of cubic boron nitride and alumiDium ~itride (a solid solution o~ aluminium i~ cubic boron nitride an~ a solid ~olu-tio~ of boxon in alumi~ium nitride) and contains 4.85 at.%
of aluminium, ~7.0 at.~0 of boron, 47.0 at.% of nitroge~, and impuritie~ - the b~lance. The density of the polycry~talline block is 3~38 ~/cu.cm.; the lattice pa;r~meter o~ th~ cubiG
pha~e is 3,610 ~.
:E x a m p ~ e 4 Th~ ~tarti~g mix*ur~ compri~es 95 perca~ by weight o~
wurtzito boron nitrido and 5 perce~t by wei~ht of elame~tary alumi~ium. ~he billet o~ de~sity 2.7 g/cuO~m~, manufacturcd i~ a procodure d~p~icating th~t o~ ~ample 1~ i~ subjected for 10 se~onds to a prassure of 85 kBar and a ~emporature o~
2,500C. ~he monolithic pol~¢rystalline block produ~ed in the ~ynthasis h~ a density of 3~42 gJcu~cm.; it compxi~es a mecha~ical mi~ture o~ mutual soiid solutions of aluminium ~itri~a and cubic boro~ nitri~e~ and conta~n~ 2.~0 at.% o~
aluminium, 48~03 at~% o~ boron, 47.83 at~0 o~ nitroge~, and L6~
impurities - the balanee. The lattiee parameter of the cubie phase is 3, 608 A.
Example 5 The starting mixture eomprises 10 pereent by weight of hexagonal boron nitride, 80 pereent by weight of wurtzite boron nitride and 10 pereent by weight of elementary aluminium.
me billet of density 3.35 g/eu.em., prepared in a proeedure duplieating that of Example 1, is subjeeted for 1 minute to a pressure of 95 kBar and a temperature of 1,800C. me monoli-thie polycr~stalline bloek of density 3.44 g/cu.cm. therebyprodueed eomprises a meehanieal mixture of mutual solid solu-tions of aluminium nitride with eubie and wurtzite-like boron nitride, eontaining 4.80 at.% of aluminium, 47.0 at.% of boron, 47.0 at.% of nitrogen, and impurities - the balanee.
Example 6 The starting mixture eomprises 1 pereent by weight of aluminium and 99 pereent by welght of hexagonal boron nitride pretreated with a mixture of sulphuric and hydrochloric acids.
The billet of density 2~11 g/cu.cm., manufactured in a proce-dure duplicating that of Example 1, is subjected for 1 minuteto a pressure of 80 kBar and a temperature of 2,200C. The monolithie polycrystalline block of density 3.46 g/cu.em. thus synthesized comprises a solid solution of aluminium in eubie boron nitride, containing 0.46 at.% of aluminium, 49.77 at.%
of boron and 49.75 at.% of nitrogen, and impurities - the ba-lanee.
3LlD9Z:~L6 -- '18 --E :g: a m p ~l e 7 ~ I!he starting mi}rture com~ri~e~ 95 percent by ~eight o$
he:~:agonal boro~ nitride, which ha~ been priorl;y puri~ied with acids, washsd and dried, a~d 5 percent by weight of aluminium.
The billet of de~sity 2.25 g/cuOcm., producad i~ a procaduro duplica~ g that o~ ~ample 1, is subjected :eor 30 s~¢o~da to a pr~ssure o~ 90 l~ar aIld a t~mperatu:r~ of 2~400C. to yield a polycrystalJirle block of dansit~ 3.41 gicu,cm.which ¢ompri-ses a solid solution o~ aluminium ~ cubic boron nitride and a ~mall qua~tity o~ a solid solution o~ boron ~ aluminium nitrid~ he blo¢k contains 2.36 at.% of alumiIlium, 48.81 at.%
oî boroll, and 48~81 at.% of nitrogen.
a m p ~ e 8 ~ he 6ta~ 1g mixture comprises 99 percollt by weight o~
he~agolla:L boro~:L nitrida alid 'I percent by weight o~ elomontary boron. The average particle size o~ the hexa~;on~ boro~ ~itride is 20 mi¢ron~; that oi~ the eleme~ary bo3~en 5 micron~
~ he billet of aensitg ~!.11 ~;/cu.cm., ma~u~actured in a p~ocedure duplicati~g that of l~cample 1 9 iæ subaected ~or 2 mi~uteæ to a pressure of 60 l~Bar a:nd a temporature OI
1,900~. to produce a polycxy~ta~line blocl~ of den~ity 3.46 g~cu.cm. which ~o~prises a æo}id æolution o~ boron i~ cubic boron :Elitride, co~tai~i~g 50.60 a~% of boron, ~9.30 at.~O o~
nitr~gen, and impurities - the bala~ce. ~he labtice parameter of t~ cubic phase is 39616 A.
~0~
- ~l9 -E x a m p ~ e 9 The starting mixture comprises 95 percent by weight o~
hexagonal boxo~ nitride and 5 percent b~ we~ght of element~r~
boro~. The billet of de~ity 2.10 g~cu~cm., manufactured in a procedure d~plicat~ng that o~ ~camp~e 1, is subjected ~or 30 seconds to a pre~sure o~ 80 kBar and a temperature o~ 2~200Ca to produce a monolithic polycrystalli~e block comprising a solid solu~ion o~ boron in cubic boro~ nitrlde9 and containing 52.8 at~% of boron, 47,1 at.% o~ ni~rogen, and impuritieY -the bala~ce. q!h~ block density is 3.~1 g/cu.cm.; 1;he lattice par~meter of the cubic phaæe i3 3~18 ~.
E x a m p ~ e 1 0 ~ 'he starting ~ixture comprises 90 perGe~t by weight of haxagonal nitride and 10 perce~t by weight OI elementa~
boxon~he billet o~ density 2.15 gJcu.cm., ma~ufactured in ~
procedure duplica~i~g that oY Example 1, is subjected ~or 20 seconds to a presæure o~ 85 kBar and a temperature of 2~400C.
to produc~ a mo~olithic polycry~,tallino blook o~ density 3A39 g~cuOcm.comprising a solid solution o~ boron in ~ubic boron ~itrid~ and nitrogen in boron ~mutual so~id solutions o~ bor~
and ¢ubic boxon nitride? and containing 55~60 at.~0 o~ boron, ~4.~0 at.~o o~ nitrogen , and impuriti~s - the balanceO
x am p l e 1 1 ~he ~tarti~g mixture comprise~ 80 percent by wei~ht o~
hexagonal boron nitrid~, 10 percenb b~ wsight of wurtzite boron nitride and 10 percent by w~ight o:E elemontar~ boron.
~he bi~let of den~ity 2035 g~cu.cm., m~ufactured in a proce-dure duplicatin~; that of ~:amaple 1, is subjected for 10 seconds to a pressure of 90 1~Bar a~d tempera~ure of 2,500C. to pro-duce a pol;srcrys~alline block of density 3040 g/cu.cm. whi¢h compri~e~ mutual solid solutions of boron and cubic bororl nitride (a ~olid ~o~utio~ of boron in cubic boron :nitride and a solid solutlon OI :~troge:r~ in boro~ d corltains 55~62 a~.5'0 oî bo~on, 44,.31 at.% of llitro~en, and impuri!tie~ - th~ bala~ce~
q~he lattiao parameter of -the cubic phase is 3,620 g.
s. m p 1 ~ 1 2 ~ he ~ g mixture aomprise~ 50 perce3~ b~ ~eight of hexagonal boron nitrid~, 30 percenl; b~ woight o~ wurtzite boron nitride a~d 20 porceIlt b;sr ~ei~h~ o~ elome~ta~y boro:~.
~he billet of density 3O35 g/cu-cm-, ma~uîactur~d in ~ proce-dure dup~icat~ng that of hxample 1, i~ subjected ~or 15 ~a-oond~; to a pros~ure oî 90 kBar a:Eld a temperature o~ 2,500~
to producs ~ pol;srcrystalli~e block o~ den~it~ 3.35 g/cu.cm.
aompri~ing m~ual ~olid ~olutions of boron and cubic boroll nibrid~ and Gs~ltiaiIliDg 61.1 at.% OI boron, 3808 ~.~0 of nitro-gen, a~d i~pur:itie3 - the b~lance.
E :~: a m p 1 e 1 3 he fibarting mi:~cture comprises 95 percent by waight o~
hex~gonal boron nitrid~ pretrea$ed to bs strippad oï impuri tiiC5 a~d 5 ~ercent by ~ei~ht of elemantary boro~. ~he billet o* d~nsity 2~10 ~/cu.cm., ma~uIactured in a procedure dupllca-~z~
_ 21 ting that of :3:xa~ple 1, is subjscted ~or 45 secorlds to apres~ure o~ 85 1~13ar and a t~mparature o~ 2,500C. to produce a polycrystalline block o~ density 3O4~ g/cu- cmO which compri-ses a solid solution o~ boron in cubi¢ boron nitride and con-tains 52.8 at,.% of boron, 47.15 a:t.% of nitro~en, arld impuri-ties - the balance.
E :~; a m p 1 e 1 4 ~ he start~g mi~ture compri~es 98 percent by weight of hexa~;onal boron nitrqda a:~d 2 per,cent by weight o~ e~ementar~
boronO ~he bi~l~3t OI de~sity 2.1 ~cu.cmO, manufactured i~ a prooodure du~lica~g that of :E~ample 1, is subjected ~or 3 millutes to a prossure OI 55 ~Bar and a tem@eraturo of 19900C.
to produce a spec~en c~mprisi~g a solid solution of boron in cubic boron ~itride and a small quantity of ho~a~ona~
boro~ nitrid~ a~d containing 51.08 ~t.% of boro~, ~8~:~0 at.%
of nitroge:tl, and impurities - the bala:~ceO
~x amp l o 1 5 !rhe ~tarti~g mixture comprises 95 percen~ by weight OI
h~xagonal boron nitridey 2.5 pe:rc~nt by wei~;h~ of elemcnt~ry aluminium and 205 percent b~ weigh~ o~ elemantary boron. The billet of donsity 2015 ~;~cu.cm., ma~u~actured i~ a procedure duplica~ing that of Exampla 1, is subjected for 2 minutes to a pressure of 60 }~Bar a~d a tempera:ture o~ 1 ,800G. to pro-duce a superhard polycrystalline block o~ dènsity 3.42 gJcu~¢mO
which comlprise~ solid solutions o~ bo~on alld a~uminium in cu-~ 8 bic boron nitride and contain~ 1.16 a~.% of aluminium, 50.80 at.% o~ boron, and 47090 ~t. % o:~ ~itro~onO
x a m p 1 e 1 6 ~ he startin~ mixture comprises 90 percent by weig~t o~
hs~$o~al boron nitride, 5 percent by wei~ht o~ wurtzite boro~
nitride, 2.5 pex~ent by weight o~ boro~ and 2.5 per~ent bg ~eight of aluminiwm. ~hs billet of density 2.3 g/cu.cm.,manu~ac-tur~d in a proc~dure duplica~ing that of :E:xample 1~ is subjec-ted for 1 mi~ute~;~ to a pressure o~ 75 kBar and a temperature of 2,100a. to produce a superhard polycry~kalline blo~k of de~sit~ 3,44 g~cuOcm. which compri~es soli~ ~o~ution~ of boron a~d alumi~i.um i~ cubic boron ~itride and co~tains 1.15 at.%
of al~minium 50.82 at~% of boron, 47.91 atO70 o~ nitrogen, a~d impuriti~ - the balance~
~ x a m p ~ e 1 7 ~ ~The sbarti~ ture compr:ises 50 percen~ b~r weigh~ o~
h~agonal boron nitrido~ 3G percent by weight of ~urtzi~
boron ~ltride, 10 percant by w~ight of elementary aluminium and 10 perc~t by weigh~ o~ alementary boronO ~he bil~ot~
ma~u~actured in a proce~ure duplicating tha~ o~ E~ample 1~
is subjected for 30 æeconds to a pressure o~ 95 ~Bar a~d a te~perature of 2~00Co to pro~uce a monolithic polyc~ystalline ~lock o~ 8upe~hard m~terial of density 3.40 glcu.cm. which comprises a macha~ical mixture of solid solutions of a~uml-~ 2 - 2~ -nium and boro~ in cubic boron ni-tride as well as a solid solu-tion of nitrogen in aluminium dodecaborid~ and contains 4.78 at.$ o~ alumi~ium, 53.50 at.% of boron, ~1.20 at.% o~ nitro-gen, and impurities - the balance.
E x a m p 1 e 1 8 The starting mixture comprises 10 percent by weight of hexagonal boron nitrido~75 percent by weight o~ wurtzite boron ~itride,5 percent by weight of slementary boron and 10 percent by weight of elementary aluminium.~he billet,manufactur~d in a procedure duplicating that of Example 1,is subjected for 45 se-co~ds to a pressure o~ 80 kBar and a temperature of 2,200C. to produce a po~ycrystàlline block com~rising solid solutions o~
aluminium and boron in cubic boron nitride and a solid solution on the basis o~ aluminium nitrido and containing ~.82 at.% of aluminium~50050 at.% of boron,44.50 at.% of nitroge~, and impu-ritie~ - the balance~
x a m p ~ e 1 9 ~ he ~tarting mixture comprises 98 percent by weight of hexagonal boron nitride, 1 percent by weight o~ elementary alu-minium and 1 percent b~ weight of elementary boro~. ~he billet, m~nufactured in a procedure duplicating that o~ ~xample 1, is subjected for 1 minute to a pressure of 65 kBar and a tempera-ture o~ 2,000C. to produce a pol~crystalline block of super-hard matorial which comprises solid solutions o~ boro~ and alu-minium in cubic boron nitride and co~tains 0.~6 at.% of a~umi-nium, 50.20 at.% o~ boron~ 49.20 at.% of nitro~en, and i~puri-ties - thc balance.
E ~ a m p ~ e 2 0 ~ he starting mixture comprises 65 percent by weight of wu~tzite boron ~itride~ 20 porcent by weight of heæagO~al Z~L6t~
boron ~tride~ 10 perceIl~ by w3ight Or aLumin1um a~d 5 ~ercent b;y weight of elem~ntary boron. ~he billet" manufactured i~ a procedur~ duplicati~g that of :E:xample 1, i~ subj~cted ~or 15 ~acoIlds to a pres~ure of 85 l~Bar a~d a tem~3erature o~ 2,300C.
to produce a polycrystallina block of superhard material o~
den~ity 3.38 ~/cuOcm. which comprise~ a mixture o~ solid so-lution3 of boron a~d a:Lumi~um i~ cubic bororl nitride a:nd a so~id solution of borox~ in alumi~um rlitride~ and co~tains 4.80 at.% of aluminium, 51;~.`51 at.% of boron~ 44.40 a~0% 0 ~itrigen9 arld impuritie~ the balfl:~ce.
B x a m p ~ e 2 1 ~ he ~tarting mi:x~ture compri~es 95 percent by weig~Lt of hegagonal boron nitride, ~ perce~ by weight o:E eleme~t~ry aluminium and ~ pe~cen~ b;sr weigh~ of eleme~tary boron. I!he billst, manufa~tured in a procedure duplica~ing that o~
:EExample '19 i~; subjected ~or 3 m:L~utes to a pros~Lre of 55 J~Bar alld a temperature of 1 ~900C. to produce a polycry~alli~e block OI ~uperhard material OI de~sity 3.40 g/cu.cm. which comprises solid so~utions o~ boron and allJminium in cubic boro:~ nitride a~d co~tains 1.87 at.% of alumi~ium9 49.61) at.%
of boron9 48.,50 at.% o~ nitrogen~ and impuritiQ~ - the balarlca~, c amp 1 e 2 2 The starting mi~ture comprises 92 percen~ by wei~ht OI
he~ ;o~al boron ~itride pretreated to be stripped of impuri-l;ies, 4 percent by wei~ht of aluminium a~d 4 perc0nt by woi~ht o~ elem~ntary boronO ~he biilet9 marlu~actured i~ a procedur~
duplicati~; that o~ æample 1~ is ~ubj~cted ~or 30 seco~d~ t~
- 25 ~ Z~L6~
a prassure of 80 l~Bar and a teml?~rature o~ 2,200C. to produce a po~ycrystalline block comprising solid ~oiut~Lons of boron and aluminium in cubic boro~ ~itride as we~l as pha~es on the basis of aluminium nitride and aluminium beride and containing 1.87 ~t.% o~ aluminium, 51.46 at.% of boron, ~6.60 at.~0 of nitrogen ~ an~ impuri-ties - the balaQce.
E x a m p l e 2 3 Ths starting mi~ture comprises 97 percent by weight o~
hexago:llal boron llitrid~ ~d 3 percent by weight of al~iminium dode¢àboride. ~he billet, manu~actured in a proceduxe dupli~
cati~g that of Example 1, is subjected for 2 minutes to a pressure of 60 kBar and a temparature o~ 1,900C. ~he end product comprises solid solutions o~ boron and aluminium in. cubic boron llitride s:lld contains 0.24 a~.% o~ ~luminium, , .. . .
51.30 at ~ o~ boron, 48.~0 at~0 of nitrogen, and impurities -the bala~ce~, E x amp l e 2 4 The starting mixture comprise 5 percent by weight of a~uminium dodeGaboxide a:tld 95 psrcent by weight of hexagon~l boron nitride~ ~he billet~ manufactured in a procedure dupli -cating that o~ h~amp~e 1, 1$ subjected ~or 45 saconds to a pre~sure o~ 75 kBar and a temperature of 2,200C. to produce polycrysta~line block of superhard matarial comprising mutual boron solid solutions of cubic~nitride and aluminium dodecaboride (solid solution~ o~ boron and a~uminium in ~ubic boron nitride a~d a solid solution of nit~ogen in aluminium dod~ca-gL68 boride) and contai~Ilg 0.39 at.~0 of alumi~ium, 5Z.10 at.~0 ofboxo~ 7.~2 ab.% of nitroger~ d impurities - the balance~
E x amp ~ e 2 5 ~ he starting mi~cture compris~ 50 percent by wei~ht of h~xagonal boro~ nitride, 35 perc~nt b;sr weight of wur~zite boro~ ;~it~ide a~d 15 percent by weight of aluminium dodeca-boride. ~h~ billet, manufactured in a procedure dup~ieating that of 13xQmp}e 1, is subjectad for 15 ~econds to a pressure of 90 k~ar arld a t~perature of 2,600~C. to produce a poly-crystQlline block o~ superhard màterial which compri~es mu-tual ~30lid ~olutio~s of cubic boron ~itxide a~d a~umi~ium dodecaborida a~d co~ains 1.18 at.% of alumi~ium, 56~40 at.%
of boron, 42.~1 a~ o of ni~ro~en, ~d impuriti~s - the ba~ ce.
~3~ amp 1 e a 6 !~?he starting mixture comprise~ 90 percent by weiæht o~
hexagonal boron nitride a~d 10 percent by weight of ~umi~um boride ~B2. The bi~let, manufactured in a procedure dupli-cati:~g that o~ Examp~e 1, is ~ubjected ~or 25 ~econds to a pre~sure of 80 ~ d a ~emperature o~ 2~400C. ~h~ ~nd pro-duct i~ compo~ed o~ mutual solld ~olutio~ o~ cubic bo:~n nit-ride a~d aluminium borid~ d con~ s 2.54 at.% of alumi~ium, 500C)2 ~t.% ~ boron, ~7,.40 at.70 o~ nitrogen, a~d im~uritio~ -the ba~a:ncs,3 :E x am p ~ e 2 7 q!he ~ta;r~ing m~tura colaprisa~ 90 perc~nt by ~Deight of he:s~agollal boron ~itride pxotreated to be ~tripped o~ impu~
_ 27 - ~IL09~168 tias~ and 10 p~rcent by weigh~ of alumi~ium boride AlB2. q!he billet, ma:~lu:Eacturad in a procedure dupllcati~g that of Example 1, is subaected ~or 15 seco:nds to a pr~ssure o~ 90 kBar and a temperature o~ 2,600C~ The end product i5 compo~
~ed o~ mutual solid ~o~utions o~ cubic boron ~itride and aluminium boride and co~tains 2.54 at.% o~ aluminium, 47~44 at~O of boron, and impuritie~ - the bala~ce.
~ he above examples illustrats the best a~loyi~g additivos, but other elements ~rom the 3rd Group o~ Mendeleev's Periodic ~ablo, such as galliwm, indium, lanthanides, yttrium or acti~i-de~ and the~r boride~ ma~ likowise serva as alloying additive.
Howev~r, i~ commercial-~cale production, said lattcr alloy-ing additives either aad consîderably to the co sts (la~th~nid~s and actinldes) and creabe ~urther inconveniences in u~e (ra-dioactivit~), or ~ail to produce any tangible ef~ect. But in a general case 9 the alloying additiv~s may be constituted by any element from the 3rd Group of the Periodic Table or a boride thereo~ capable of forming tetrahedral bonds.
~ ho ~uperhard mat~rial of this invention may be employ-ed ~or finishing and semifi~iahing cast iron and quenched steel (HRC: from 55 to 64) as w~ll as other hi~h-ten~ile and churlish materials. The ~utti~g speed varies ~rom 40 to 400 m/min. D ope~ding on the type of material to be worked ~cu~bers fitted with the proposed superhard material may require ~harpe~-i~g at i~tervals from 60 to 200 minutes. ~hus, for e~ample, employed for working chromium ball-beari~g ~teel of Rockwell C
hardna~ 62 to 64 at a cutting speed of 80 m/min, a cut~ing - 28 ~ 923L6~
depth of 0.2 mm and a f~ed o~ 0.07 mmJrevolutio~, cutters fitted wi~h the sup~rhard ma~erial o~ thi~ entio~ require sharpening after 80 to 105 minutes of ~ervice. Emp~o~ed for working chromium-vanadium steels o~ the same hardn~ss and at -the same set of cutting conditions, cutters fitted with ~he supe~-haxd material o~ the inYention re~uire sharpe~ing after 120 to 200 minute~ of se~vice. The data characterizi~g tha durabi-lity of the cu~t~rs are given for the case where no cooling wa~ us~d. Si~ce the prsposed superhard material contain~ no components decomposing on exposure to moisture,coollng can ba used whi~e cu~lng, accordi~gly i~creasing the durability o~ the cutt~rs. Cutters fitted with the superhard matorial o~ the inventio~ work surface to a high grade of fini~h, ~llowing of di~pensing with grinding in maDy applicatio~s.
A.p~rt from cutters, the proposed superhard material mfl~ be employed i~ d~illing bit~ Llls, saws ~d other like tool~la If need be, the propo~ed ~uperhard mat~rial ma~y be manu-~actured i~ the fo:rm of an a~rasive powder as lvell. ~o this end the syntha~is is ~topp~d before completion alld the end product is :~reed :E:rom no~-abra~i~Te compone~ts (he:~c~;onal boron nitride) .
~ he proces~ for the production of superhard matarial described in the iIlve~tîo:~l produces hi~h-quality polycrysta:L-line blocks of supsrhard material. ~he yield of blocks sui-table for use in tool~ e:~¢eed~ 60 percenb and ma;sr be raised as high as 95 perce~lt if the entire potential for proce~s - 29 ~ 92~6~
impro~ed is utilized. ~he proce~s is ea~y to impleme~t and ca~ thus be in-troduced into commercial production without a~ dif~icult~. Shou~d the proces~ be realized with ~he usa of the above-described high-pressure apparatus, the end pro-duct take~ the ~orm o~ polycryætalline blocks of ~uperhard matorial measuring 4 to 6 mm in diameter and 3.5 to 5~6 mm in hei~ht. Usin~ more adva~ced equipment, the authors have obtained supe~hard pol~crys-tals i~ the ~orm of c~ ders 8 to 10 mm high and 10 to 12 mm in diameter. '~he polycrysta~s pro-, duced in the proposed proces~ may be even ~arg~r, th~ onlylimitation on ~ize bei~g the potentia~ities of the proce~s eguipment~
o~ , 49.76 at~% of boron, ~9.76 at.~ o~ nitrogen, and impuritie~ - the bala~ce, is withdra~n from the chamber. ~he density of the product polycr~tal is 3.46 g~cu~cm. ~he la~ti-ee parameter o~ th~ cubic phase is 3961~ ~.
E x a m p ~ e 2 The starting miYture compri~e~ 95 percent by weight o~
hexagonal boron ~itride and 5 perce~t by weigh~ of elemen-tary a~uminium. The density o~ t:he moldod billet iB 2.20 g/cu~cm. SubjeGting the billet to a pres~ure o~ 7~ kBar and a temperature of 29100C. for 30 seconds yields a mono-lithic polycr~stalline block made up o~ a solid so~utio~ .
ef aluminium in cublc boro~ DitrideJ the billet being mol-ded in a procedure dup~ica~i~g tha~ o~ ~xamp~e 1. ~-ray phasc-sh~ ahaly~is ~e~eals traces o~ an alumi ~ um nitride-~ase phase. F~he d6n~ity o~ the pol~cry~tal i~ 3042 g/cu.cm.
The lattice parameter of the cubic pha~e i8 about 3,610~.
F~h~ spe~ime~ co~tains 2.36 at,.% o:e alumi~ium, 48.80 at.% of boxont 48.80 a~.% OI nitroge~,the balance bei~ impuritie3.
E x a m p ~ o 3 ~ he starting mi~*ure compri~cs 80 percent by wei~ht of he2:agonal boron llitride, 10 percsnt by w0ight of wurt-zite b~ro~ nitride a~d 10 perce~t by weight of elementary alumi ni~m~ æhe billet of den~ity 2.30 g/cu~cm. molded in a pro-cedure duplicating that of Example 1, i5 subaected to a p~es~ure o~ 85 kBar a~d a t~mper~ture of 2,~00C. for 15 ~e-conds. ~he monolithi¢ polycrysta~line block thu~ producod i~
constituted b~ a mech~ical mixture of mutual ~olid solu-tion~ of cubic boron nitride and alumiDium ~itride (a solid solution o~ aluminium i~ cubic boron nitride an~ a solid ~olu-tio~ of boxon in alumi~ium nitride) and contains 4.85 at.%
of aluminium, ~7.0 at.~0 of boron, 47.0 at.% of nitroge~, and impuritie~ - the b~lance. The density of the polycry~talline block is 3~38 ~/cu.cm.; the lattice pa;r~meter o~ th~ cubiG
pha~e is 3,610 ~.
:E x a m p ~ e 4 Th~ ~tarti~g mix*ur~ compri~es 95 perca~ by weight o~
wurtzito boron nitrido and 5 perce~t by wei~ht of elame~tary alumi~ium. ~he billet o~ de~sity 2.7 g/cuO~m~, manufacturcd i~ a procodure d~p~icating th~t o~ ~ample 1~ i~ subjected for 10 se~onds to a prassure of 85 kBar and a ~emporature o~
2,500C. ~he monolithic pol~¢rystalline block produ~ed in the ~ynthasis h~ a density of 3~42 gJcu~cm.; it compxi~es a mecha~ical mi~ture o~ mutual soiid solutions of aluminium ~itri~a and cubic boro~ nitri~e~ and conta~n~ 2.~0 at.% o~
aluminium, 48~03 at~% o~ boron, 47.83 at~0 o~ nitroge~, and L6~
impurities - the balanee. The lattiee parameter of the cubie phase is 3, 608 A.
Example 5 The starting mixture eomprises 10 pereent by weight of hexagonal boron nitride, 80 pereent by weight of wurtzite boron nitride and 10 pereent by weight of elementary aluminium.
me billet of density 3.35 g/eu.em., prepared in a proeedure duplieating that of Example 1, is subjeeted for 1 minute to a pressure of 95 kBar and a temperature of 1,800C. me monoli-thie polycr~stalline bloek of density 3.44 g/cu.cm. therebyprodueed eomprises a meehanieal mixture of mutual solid solu-tions of aluminium nitride with eubie and wurtzite-like boron nitride, eontaining 4.80 at.% of aluminium, 47.0 at.% of boron, 47.0 at.% of nitrogen, and impurities - the balanee.
Example 6 The starting mixture eomprises 1 pereent by weight of aluminium and 99 pereent by welght of hexagonal boron nitride pretreated with a mixture of sulphuric and hydrochloric acids.
The billet of density 2~11 g/cu.cm., manufactured in a proce-dure duplicating that of Example 1, is subjected for 1 minuteto a pressure of 80 kBar and a temperature of 2,200C. The monolithie polycrystalline block of density 3.46 g/cu.em. thus synthesized comprises a solid solution of aluminium in eubie boron nitride, containing 0.46 at.% of aluminium, 49.77 at.%
of boron and 49.75 at.% of nitrogen, and impurities - the ba-lanee.
3LlD9Z:~L6 -- '18 --E :g: a m p ~l e 7 ~ I!he starting mi}rture com~ri~e~ 95 percent by ~eight o$
he:~:agonal boro~ nitride, which ha~ been priorl;y puri~ied with acids, washsd and dried, a~d 5 percent by weight of aluminium.
The billet of de~sity 2.25 g/cuOcm., producad i~ a procaduro duplica~ g that o~ ~ample 1, is subjected :eor 30 s~¢o~da to a pr~ssure o~ 90 l~ar aIld a t~mperatu:r~ of 2~400C. to yield a polycrystalJirle block of dansit~ 3.41 gicu,cm.which ¢ompri-ses a solid solution o~ aluminium ~ cubic boron nitride and a ~mall qua~tity o~ a solid solution o~ boron ~ aluminium nitrid~ he blo¢k contains 2.36 at.% of alumiIlium, 48.81 at.%
oî boroll, and 48~81 at.% of nitrogen.
a m p ~ e 8 ~ he 6ta~ 1g mixture comprises 99 percollt by weight o~
he~agolla:L boro~:L nitrida alid 'I percent by weight o~ elomontary boron. The average particle size o~ the hexa~;on~ boro~ ~itride is 20 mi¢ron~; that oi~ the eleme~ary bo3~en 5 micron~
~ he billet of aensitg ~!.11 ~;/cu.cm., ma~u~actured in a p~ocedure duplicati~g that of l~cample 1 9 iæ subaected ~or 2 mi~uteæ to a pressure of 60 l~Bar a:nd a temporature OI
1,900~. to produce a polycxy~ta~line blocl~ of den~ity 3.46 g~cu.cm. which ~o~prises a æo}id æolution o~ boron i~ cubic boron :Elitride, co~tai~i~g 50.60 a~% of boron, ~9.30 at.~O o~
nitr~gen, and impurities - the bala~ce. ~he labtice parameter of t~ cubic phase is 39616 A.
~0~
- ~l9 -E x a m p ~ e 9 The starting mixture comprises 95 percent by weight o~
hexagonal boxo~ nitride and 5 percent b~ we~ght of element~r~
boro~. The billet of de~ity 2.10 g~cu~cm., manufactured in a procedure d~plicat~ng that o~ ~camp~e 1, is subjected ~or 30 seconds to a pre~sure o~ 80 kBar and a temperature o~ 2~200Ca to produce a monolithic polycrystalli~e block comprising a solid solu~ion o~ boron in cubic boro~ nitrlde9 and containing 52.8 at~% of boron, 47,1 at.% o~ ni~rogen, and impuritieY -the bala~ce. q!h~ block density is 3.~1 g/cu.cm.; 1;he lattice par~meter of the cubic phaæe i3 3~18 ~.
E x a m p ~ e 1 0 ~ 'he starting ~ixture comprises 90 perGe~t by weight of haxagonal nitride and 10 perce~t by weight OI elementa~
boxon~he billet o~ density 2.15 gJcu.cm., ma~ufactured in ~
procedure duplica~i~g that oY Example 1, is subjected ~or 20 seconds to a presæure o~ 85 kBar and a temperature of 2~400C.
to produc~ a mo~olithic polycry~,tallino blook o~ density 3A39 g~cuOcm.comprising a solid solution o~ boron in ~ubic boron ~itrid~ and nitrogen in boron ~mutual so~id solutions o~ bor~
and ¢ubic boxon nitride? and containing 55~60 at.~0 o~ boron, ~4.~0 at.~o o~ nitrogen , and impuriti~s - the balanceO
x am p l e 1 1 ~he ~tarti~g mixture comprise~ 80 percent by wei~ht o~
hexagonal boron nitrid~, 10 percenb b~ wsight of wurtzite boron nitride and 10 percent by w~ight o:E elemontar~ boron.
~he bi~let of den~ity 2035 g~cu.cm., m~ufactured in a proce-dure duplicatin~; that of ~:amaple 1, is subjected for 10 seconds to a pressure of 90 1~Bar a~d tempera~ure of 2,500C. to pro-duce a pol;srcrys~alline block of density 3040 g/cu.cm. whi¢h compri~e~ mutual solid solutions of boron and cubic bororl nitride (a ~olid ~o~utio~ of boron in cubic boron :nitride and a solid solutlon OI :~troge:r~ in boro~ d corltains 55~62 a~.5'0 oî bo~on, 44,.31 at.% of llitro~en, and impuri!tie~ - th~ bala~ce~
q~he lattiao parameter of -the cubic phase is 3,620 g.
s. m p 1 ~ 1 2 ~ he ~ g mixture aomprise~ 50 perce3~ b~ ~eight of hexagonal boron nitrid~, 30 percenl; b~ woight o~ wurtzite boron nitride a~d 20 porceIlt b;sr ~ei~h~ o~ elome~ta~y boro:~.
~he billet of density 3O35 g/cu-cm-, ma~uîactur~d in ~ proce-dure dup~icat~ng that of hxample 1, i~ subjected ~or 15 ~a-oond~; to a pros~ure oî 90 kBar a:Eld a temperature o~ 2,500~
to producs ~ pol;srcrystalli~e block o~ den~it~ 3.35 g/cu.cm.
aompri~ing m~ual ~olid ~olutions of boron and cubic boroll nibrid~ and Gs~ltiaiIliDg 61.1 at.% OI boron, 3808 ~.~0 of nitro-gen, a~d i~pur:itie3 - the b~lance.
E :~: a m p 1 e 1 3 he fibarting mi:~cture comprises 95 percent by waight o~
hex~gonal boron nitrid~ pretrea$ed to bs strippad oï impuri tiiC5 a~d 5 ~ercent by ~ei~ht of elemantary boro~. ~he billet o* d~nsity 2~10 ~/cu.cm., ma~uIactured in a procedure dupllca-~z~
_ 21 ting that of :3:xa~ple 1, is subjscted ~or 45 secorlds to apres~ure o~ 85 1~13ar and a t~mparature o~ 2,500C. to produce a polycrystalline block o~ density 3O4~ g/cu- cmO which compri-ses a solid solution o~ boron in cubi¢ boron nitride and con-tains 52.8 at,.% of boron, 47.15 a:t.% of nitro~en, arld impuri-ties - the balance.
E :~; a m p 1 e 1 4 ~ he start~g mi~ture compri~es 98 percent by weight of hexa~;onal boron nitrqda a:~d 2 per,cent by weight o~ e~ementar~
boronO ~he bi~l~3t OI de~sity 2.1 ~cu.cmO, manufactured i~ a prooodure du~lica~g that of :E~ample 1, is subjected ~or 3 millutes to a prossure OI 55 ~Bar and a tem@eraturo of 19900C.
to produce a spec~en c~mprisi~g a solid solution of boron in cubic boron ~itride and a small quantity of ho~a~ona~
boro~ nitrid~ a~d containing 51.08 ~t.% of boro~, ~8~:~0 at.%
of nitroge:tl, and impurities - the bala:~ceO
~x amp l o 1 5 !rhe ~tarti~g mixture comprises 95 percen~ by weight OI
h~xagonal boron nitridey 2.5 pe:rc~nt by wei~;h~ of elemcnt~ry aluminium and 205 percent b~ weigh~ o~ elemantary boron. The billet of donsity 2015 ~;~cu.cm., ma~u~actured i~ a procedure duplica~ing that of Exampla 1, is subjected for 2 minutes to a pressure of 60 }~Bar a~d a tempera:ture o~ 1 ,800G. to pro-duce a superhard polycrystalline block o~ dènsity 3.42 gJcu~¢mO
which comlprise~ solid solutions o~ bo~on alld a~uminium in cu-~ 8 bic boron nitride and contain~ 1.16 a~.% of aluminium, 50.80 at.% o~ boron, and 47090 ~t. % o:~ ~itro~onO
x a m p 1 e 1 6 ~ he startin~ mixture comprises 90 percent by weig~t o~
hs~$o~al boron nitride, 5 percent by wei~ht o~ wurtzite boro~
nitride, 2.5 pex~ent by weight o~ boro~ and 2.5 per~ent bg ~eight of aluminiwm. ~hs billet of density 2.3 g/cu.cm.,manu~ac-tur~d in a proc~dure duplica~ing that of :E:xample 1~ is subjec-ted for 1 mi~ute~;~ to a pressure o~ 75 kBar and a temperature of 2,100a. to produce a superhard polycry~kalline blo~k of de~sit~ 3,44 g~cuOcm. which compri~es soli~ ~o~ution~ of boron a~d alumi~i.um i~ cubic boron ~itride and co~tains 1.15 at.%
of al~minium 50.82 at~% of boron, 47.91 atO70 o~ nitrogen, a~d impuriti~ - the balance~
~ x a m p ~ e 1 7 ~ ~The sbarti~ ture compr:ises 50 percen~ b~r weigh~ o~
h~agonal boron nitrido~ 3G percent by weight of ~urtzi~
boron ~ltride, 10 percant by w~ight of elementary aluminium and 10 perc~t by weigh~ o~ alementary boronO ~he bil~ot~
ma~u~actured in a proce~ure duplicating tha~ o~ E~ample 1~
is subjected for 30 æeconds to a pressure o~ 95 ~Bar a~d a te~perature of 2~00Co to pro~uce a monolithic polyc~ystalline ~lock o~ 8upe~hard m~terial of density 3.40 glcu.cm. which comprises a macha~ical mixture of solid solutions of a~uml-~ 2 - 2~ -nium and boro~ in cubic boron ni-tride as well as a solid solu-tion of nitrogen in aluminium dodecaborid~ and contains 4.78 at.$ o~ alumi~ium, 53.50 at.% of boron, ~1.20 at.% o~ nitro-gen, and impurities - the balance.
E x a m p 1 e 1 8 The starting mixture comprises 10 percent by weight of hexagonal boron nitrido~75 percent by weight o~ wurtzite boron ~itride,5 percent by weight of slementary boron and 10 percent by weight of elementary aluminium.~he billet,manufactur~d in a procedure duplicating that of Example 1,is subjected for 45 se-co~ds to a pressure o~ 80 kBar and a temperature of 2,200C. to produce a po~ycrystàlline block com~rising solid solutions o~
aluminium and boron in cubic boron nitride and a solid solution on the basis o~ aluminium nitrido and containing ~.82 at.% of aluminium~50050 at.% of boron,44.50 at.% of nitroge~, and impu-ritie~ - the balance~
x a m p ~ e 1 9 ~ he ~tarting mixture comprises 98 percent by weight of hexagonal boron nitride, 1 percent by weight o~ elementary alu-minium and 1 percent b~ weight of elementary boro~. ~he billet, m~nufactured in a procedure duplicating that o~ ~xample 1, is subjected for 1 minute to a pressure of 65 kBar and a tempera-ture o~ 2,000C. to produce a pol~crystalline block of super-hard matorial which comprises solid solutions o~ boro~ and alu-minium in cubic boron nitride and co~tains 0.~6 at.% of a~umi-nium, 50.20 at.% o~ boron~ 49.20 at.% of nitro~en, and i~puri-ties - thc balance.
E ~ a m p ~ e 2 0 ~ he starting mixture comprises 65 percent by weight of wu~tzite boron ~itride~ 20 porcent by weight of heæagO~al Z~L6t~
boron ~tride~ 10 perceIl~ by w3ight Or aLumin1um a~d 5 ~ercent b;y weight of elem~ntary boron. ~he billet" manufactured i~ a procedur~ duplicati~g that of :E:xample 1, i~ subj~cted ~or 15 ~acoIlds to a pres~ure of 85 l~Bar a~d a tem~3erature o~ 2,300C.
to produce a polycrystallina block of superhard material o~
den~ity 3.38 ~/cuOcm. which comprise~ a mixture o~ solid so-lution3 of boron a~d a:Lumi~um i~ cubic bororl nitride a:nd a so~id solution of borox~ in alumi~um rlitride~ and co~tains 4.80 at.% of aluminium, 51;~.`51 at.% of boron~ 44.40 a~0% 0 ~itrigen9 arld impuritie~ the balfl:~ce.
B x a m p ~ e 2 1 ~ he ~tarting mi:x~ture compri~es 95 percent by weig~Lt of hegagonal boron nitride, ~ perce~ by weight o:E eleme~t~ry aluminium and ~ pe~cen~ b;sr weigh~ of eleme~tary boron. I!he billst, manufa~tured in a procedure duplica~ing that o~
:EExample '19 i~; subjected ~or 3 m:L~utes to a pros~Lre of 55 J~Bar alld a temperature of 1 ~900C. to produce a polycry~alli~e block OI ~uperhard material OI de~sity 3.40 g/cu.cm. which comprises solid so~utions o~ boron and allJminium in cubic boro:~ nitride a~d co~tains 1.87 at.% of alumi~ium9 49.61) at.%
of boron9 48.,50 at.% o~ nitrogen~ and impuritiQ~ - the balarlca~, c amp 1 e 2 2 The starting mi~ture comprises 92 percen~ by wei~ht OI
he~ ;o~al boron ~itride pretreated to be stripped of impuri-l;ies, 4 percent by wei~ht of aluminium a~d 4 perc0nt by woi~ht o~ elem~ntary boronO ~he biilet9 marlu~actured i~ a procedur~
duplicati~; that o~ æample 1~ is ~ubj~cted ~or 30 seco~d~ t~
- 25 ~ Z~L6~
a prassure of 80 l~Bar and a teml?~rature o~ 2,200C. to produce a po~ycrystalline block comprising solid ~oiut~Lons of boron and aluminium in cubic boro~ ~itride as we~l as pha~es on the basis of aluminium nitride and aluminium beride and containing 1.87 ~t.% o~ aluminium, 51.46 at.% of boron, ~6.60 at.~0 of nitrogen ~ an~ impuri-ties - the balaQce.
E x a m p l e 2 3 Ths starting mi~ture comprises 97 percent by weight o~
hexago:llal boron llitrid~ ~d 3 percent by weight of al~iminium dode¢àboride. ~he billet, manu~actured in a proceduxe dupli~
cati~g that of Example 1, is subjected for 2 minutes to a pressure of 60 kBar and a temparature o~ 1,900C. ~he end product comprises solid solutions o~ boron and aluminium in. cubic boron llitride s:lld contains 0.24 a~.% o~ ~luminium, , .. . .
51.30 at ~ o~ boron, 48.~0 at~0 of nitrogen, and impurities -the bala~ce~, E x amp l e 2 4 The starting mixture comprise 5 percent by weight of a~uminium dodeGaboxide a:tld 95 psrcent by weight of hexagon~l boron nitride~ ~he billet~ manufactured in a procedure dupli -cating that o~ h~amp~e 1, 1$ subjected ~or 45 saconds to a pre~sure o~ 75 kBar and a temperature of 2,200C. to produce polycrysta~line block of superhard matarial comprising mutual boron solid solutions of cubic~nitride and aluminium dodecaboride (solid solution~ o~ boron and a~uminium in ~ubic boron nitride a~d a solid solution of nit~ogen in aluminium dod~ca-gL68 boride) and contai~Ilg 0.39 at.~0 of alumi~ium, 5Z.10 at.~0 ofboxo~ 7.~2 ab.% of nitroger~ d impurities - the balance~
E x amp ~ e 2 5 ~ he starting mi~cture compris~ 50 percent by wei~ht of h~xagonal boro~ nitride, 35 perc~nt b;sr weight of wur~zite boro~ ;~it~ide a~d 15 percent by weight of aluminium dodeca-boride. ~h~ billet, manufactured in a procedure dup~ieating that of 13xQmp}e 1, is subjectad for 15 ~econds to a pressure of 90 k~ar arld a t~perature of 2,600~C. to produce a poly-crystQlline block o~ superhard màterial which compri~es mu-tual ~30lid ~olutio~s of cubic boron ~itxide a~d a~umi~ium dodecaborida a~d co~ains 1.18 at.% of alumi~ium, 56~40 at.%
of boron, 42.~1 a~ o of ni~ro~en, ~d impuriti~s - the ba~ ce.
~3~ amp 1 e a 6 !~?he starting mixture comprise~ 90 percent by weiæht o~
hexagonal boron nitride a~d 10 percent by weight of ~umi~um boride ~B2. The bi~let, manufactured in a procedure dupli-cati:~g that o~ Examp~e 1, is ~ubjected ~or 25 ~econds to a pre~sure of 80 ~ d a ~emperature o~ 2~400C. ~h~ ~nd pro-duct i~ compo~ed o~ mutual solld ~olutio~ o~ cubic bo:~n nit-ride a~d aluminium borid~ d con~ s 2.54 at.% of alumi~ium, 500C)2 ~t.% ~ boron, ~7,.40 at.70 o~ nitrogen, a~d im~uritio~ -the ba~a:ncs,3 :E x am p ~ e 2 7 q!he ~ta;r~ing m~tura colaprisa~ 90 perc~nt by ~Deight of he:s~agollal boron ~itride pxotreated to be ~tripped o~ impu~
_ 27 - ~IL09~168 tias~ and 10 p~rcent by weigh~ of alumi~ium boride AlB2. q!he billet, ma:~lu:Eacturad in a procedure dupllcati~g that of Example 1, is subaected ~or 15 seco:nds to a pr~ssure o~ 90 kBar and a temperature o~ 2,600C~ The end product i5 compo~
~ed o~ mutual solid ~o~utions o~ cubic boron ~itride and aluminium boride and co~tains 2.54 at.% o~ aluminium, 47~44 at~O of boron, and impuritie~ - the bala~ce.
~ he above examples illustrats the best a~loyi~g additivos, but other elements ~rom the 3rd Group o~ Mendeleev's Periodic ~ablo, such as galliwm, indium, lanthanides, yttrium or acti~i-de~ and the~r boride~ ma~ likowise serva as alloying additive.
Howev~r, i~ commercial-~cale production, said lattcr alloy-ing additives either aad consîderably to the co sts (la~th~nid~s and actinldes) and creabe ~urther inconveniences in u~e (ra-dioactivit~), or ~ail to produce any tangible ef~ect. But in a general case 9 the alloying additiv~s may be constituted by any element from the 3rd Group of the Periodic Table or a boride thereo~ capable of forming tetrahedral bonds.
~ ho ~uperhard mat~rial of this invention may be employ-ed ~or finishing and semifi~iahing cast iron and quenched steel (HRC: from 55 to 64) as w~ll as other hi~h-ten~ile and churlish materials. The ~utti~g speed varies ~rom 40 to 400 m/min. D ope~ding on the type of material to be worked ~cu~bers fitted with the proposed superhard material may require ~harpe~-i~g at i~tervals from 60 to 200 minutes. ~hus, for e~ample, employed for working chromium ball-beari~g ~teel of Rockwell C
hardna~ 62 to 64 at a cutting speed of 80 m/min, a cut~ing - 28 ~ 923L6~
depth of 0.2 mm and a f~ed o~ 0.07 mmJrevolutio~, cutters fitted wi~h the sup~rhard ma~erial o~ thi~ entio~ require sharpening after 80 to 105 minutes of ~ervice. Emp~o~ed for working chromium-vanadium steels o~ the same hardn~ss and at -the same set of cutting conditions, cutters fitted with ~he supe~-haxd material o~ the inYention re~uire sharpe~ing after 120 to 200 minute~ of se~vice. The data characterizi~g tha durabi-lity of the cu~t~rs are given for the case where no cooling wa~ us~d. Si~ce the prsposed superhard material contain~ no components decomposing on exposure to moisture,coollng can ba used whi~e cu~lng, accordi~gly i~creasing the durability o~ the cutt~rs. Cutters fitted with the superhard matorial o~ the inventio~ work surface to a high grade of fini~h, ~llowing of di~pensing with grinding in maDy applicatio~s.
A.p~rt from cutters, the proposed superhard material mfl~ be employed i~ d~illing bit~ Llls, saws ~d other like tool~la If need be, the propo~ed ~uperhard mat~rial ma~y be manu-~actured i~ the fo:rm of an a~rasive powder as lvell. ~o this end the syntha~is is ~topp~d before completion alld the end product is :~reed :E:rom no~-abra~i~Te compone~ts (he:~c~;onal boron nitride) .
~ he proces~ for the production of superhard matarial described in the iIlve~tîo:~l produces hi~h-quality polycrysta:L-line blocks of supsrhard material. ~he yield of blocks sui-table for use in tool~ e:~¢eed~ 60 percenb and ma;sr be raised as high as 95 perce~lt if the entire potential for proce~s - 29 ~ 92~6~
impro~ed is utilized. ~he proce~s is ea~y to impleme~t and ca~ thus be in-troduced into commercial production without a~ dif~icult~. Shou~d the proces~ be realized with ~he usa of the above-described high-pressure apparatus, the end pro-duct take~ the ~orm o~ polycryætalline blocks of ~uperhard matorial measuring 4 to 6 mm in diameter and 3.5 to 5~6 mm in hei~ht. Usin~ more adva~ced equipment, the authors have obtained supe~hard pol~crys-tals i~ the ~orm of c~ ders 8 to 10 mm high and 10 to 12 mm in diameter. '~he polycrysta~s pro-, duced in the proposed proces~ may be even ~arg~r, th~ onlylimitation on ~ize bei~g the potentia~ities of the proce~s eguipment~
Claims (28)
1. A superhard material represented by a solid solution in a close-packed modification of boron nitride of at least 0.1 atomic percent of an element from the 3rd-group of the Periodic Table capable of forming tetrahedral bonds, the solid solution having the following composition, atomic %:
- boron, from about 42 to about 61 - nitrogen, from about 39 to about 50 - 3rd Group element, from 0.1 to about 30 - other impurities, from 0 to 2, provided the atomic % of said composition does not exceed 100.
- boron, from about 42 to about 61 - nitrogen, from about 39 to about 50 - 3rd Group element, from 0.1 to about 30 - other impurities, from 0 to 2, provided the atomic % of said composition does not exceed 100.
2. A superhard material as claimed in claim 1, which is a solid solution of boron in cubic boron nitride.
3. A superhard material as claimed in claim 1, which is a solid solution of boron in cubic boron nitride and has a lattice parameter of about 3,620 .ANG. .
4. A superhard material as claimed in claim 2, which is a solid solution of nitrogen in boron alongside the solid solution of boron in cubic boron nitride.
5. A superhard material as claimed in claim 1, which is a solid solution of aluminium in cubic boron nitride.
6. A superhard material as claimed in claim 5, in which the lattice parameter is about 3,610 .ANG. .
7. A superhard material as claimed in claim 5, which comprises a solid solution of boron in aluminium nitride alongside the solid solution of aluminium in cubic boron nitride.
8. A superhard material as claimed in claim 1, which comprises a mechanical mixture of a solid solution of aluminium in cubic boron nitride and a solid solution of boron in cubic boron nitride.
9. A superhard material as claimed in claim 8, which comprises solid solutions of aluminium in cubic boron nitride and boron in cubic boron nitride alongside solid solutions of boron in aluminium borides.
10. A superhard material as claimed in claim 8, which comprises solid solutions of aluminium in cubic boron nitride and boron in cubic boron nitride alongside solid solutions of boron in aluminium nitride.
11. A superhard material as claimed in claim 8, which comprises solid solutions of nitrogen in aluminium borides alongside the solid solutions of aluminium in cubic boron nitride and boron in cubic boron nitride.
12. A superhard material as claimed in claim 10, which additionally comprises solid solutions of a 3rd-Group element in cubic boron nitride.
13. A process for the production of superhard material, which comprises preparing a feedstock mixture composed of a source of boron and a source of nitrogen, the boron and the nitrogen being in a stoichiometric ratio, and an additive accounting for from 1 to 50 percent by weight of the mixture, the additive being constituted by at least one element from the 3rd-Group of the Periodic Table capable of forming tetrahedral bonds, and exposing said feedstock mixture to a pressure of from about 50 to about 95 kBar and a temperature of from about 1,500 to about 3,000°C.
14. A process as claimed in claim 13, in which the 3rd-Group element is constituted by boron.
15. A process as claimed in claim 13, in which the additive is constituted by aluminium.
16. A process as claimed in claim 13, in which the additive is constituted by a mixture of aluminium and boron.
17. A process for the production of superhard material as claimed in claim 14, in which the additive is constituted by aluminium borides.
18. A process as claimed in claim 13, in which the source of boron and nitrogen is constituted by hexagonal boron nitride.
19. A process for the production of superhard material as claimed in claim 13, in which the source of boron and nitrogen is constituted by wurtzite-like boron nitride.
20. A process for the production of superhard material as claimed in claim 13, in which the source of boron and nitrogen is constituted by a mixture of hexagonal boron nitride and wurtzite-like boron nitride.
21. A process for the production of superhard material as claimed in claim 13, in which the feedstock mixture compo-nents have particle sizes in the range from 5 to 100 microns.
22. A process for the production of superhard material as claimed in claim 13, in which the feedstock mixture compo-nents have a particle size of about 20 microns.
23. A process for the production of superhard material as claimed in claim 13, in which the feedstock mixture is subjected to molding at a pressure of from 3,000 to 10,000 kg/sq.cm. to be given a specified billet shape.
24. A process for the production of superhard material as claimed in claim 23, in which the billet is stripped of moisture prior to the synthesis step.
25. A process for the production of a superhard material, which comprises preparing a feedstock mixture composed of a source of boron and a source of nitrogen, the boron and the nitrogen being in a stoichiometric ratio, and an additive constituted by at least one boride of an element from the 3rd-Group of the Periodic Table capable of forming tetrahedral bonds, the additive accounting for from 1 to 50 percent by weight of the mixture, and exposing the feedstock mixture to a pressure of from about 50 to about 95kBar at a temperature, of from about 1,500 to about 3,000°C.
26. A process as claimed in claim 25, in which the source of boron and nitrogen is constituted by hexagonal boron nitride.
27. A process for the production of superhard material as claimed in claim 25, in which the source of boron and nitrogen is constituted by wurtzite-like boron nitride.
28. A process for the production of superhard material as claimed in claim 25, in which the source of boron and nitrogen is constituted by a mixture of hexagonal and wurtzite-like modifications of boron nitride.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA266,758A CA1092168A (en) | 1976-11-29 | 1976-11-29 | Boron nitride-base superhard material and process for the production of same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA266,758A CA1092168A (en) | 1976-11-29 | 1976-11-29 | Boron nitride-base superhard material and process for the production of same |
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| Publication Number | Publication Date |
|---|---|
| CA1092168A true CA1092168A (en) | 1980-12-23 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA266,758A Expired CA1092168A (en) | 1976-11-29 | 1976-11-29 | Boron nitride-base superhard material and process for the production of same |
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1976
- 1976-11-29 CA CA266,758A patent/CA1092168A/en not_active Expired
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