CA2236818A1 - Whisker reinforced ceramic cutting tool and composition thereof - Google Patents
Whisker reinforced ceramic cutting tool and composition thereof Download PDFInfo
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Abstract
A ceramic composition produced by the consolidation of a blend of starting components. The composition comprises a matrix with one or more of the carbides, nitrides and carbonitrides of hafnium, molybdenum, zirconium, tantalum, niobium, vanadium, tungsten and titanium, and solid solutions thereof in an amount that is greater than 50 volume percent of the matrix. The matrix comprises between 60 and 99.8 volume percent of the composition. Ceramic whiskers are uniformly dispersed throughout the matrix wherein the ceramic whiskers comprises between 0.2 and 40 volume percent of the composition.
Description
CA 02236818 1998-0~-0~
~{I8RER ~ ZD~TC ~ lNG TOOL
AND COIIPO~ITION ~ K~ G~
BACKGROUND OF THE lN v~;N~ oN
The present invention pertains to a ceramic cutting tool, and a composition thereof, that has Whi sk~r reinfo,~ ent. More specifically, the invention pertains to a ceramic cutting tool, and a composition thereof, that has ceramic whisker reinforcement wherein at least 50 volume percent of the ceramic matrix comprises a carbide, nitride and/or carbonitride of titanium, hafnium, molybdenum, zirconium, tantalum, niobium, vanadium and/or Lun~en.
In the past, there have been ceramic bodies with Wh i ~k~r reinforcement such as that disclosed in U.S. Patent No. 4,543,345 to Wei. The Wei Patent discloses an alumina matrix with silicon carbide whicker reinforcement, a boron carbide matrix with silicon carbide whiskers, and a mullite matrix with silicon carbide whiskers. According to the Wei patent, the incorporation of silicon carbide whiskers increased the fracture toughness of the substrate.
Japanese Publication No. 63-10758 to Yamagawa et al. pertains to a ceramic composite that comprises ~ alumina as its main component. The balance comprises between 5 to 40 weight TiC and 2 to 40 weight percent silicon carbide whiskers. The combined amount of titanium carbide and silicon carbide whiskers cannot ce~ 50 weight percent, i.e., it is 50 weight percent or less. This document also mentions that there can be up to 10 weight percent of an oxide, carbide or nitride CA 022368l8 l998-0~-0~
o~ aluminum, silicon and the Group IVa, Va and VIa elements.
U.S. Patent No. 4,507,224 to Toibana et al. makes general re~erence to certain nitrides and carbides as suitable matrix material, along with electroconduetive powder, ~or SiC ~iber rein~orcement. The SiC ~ibers are present in an amount between 5 and 50 weight percent.
The '224 patent makes specific re~erence to matrices o~
silicon nitride, aluminum nitride, boron nitride, silicon carbide, boron carbide, and titanium carbide.
The '224 Patent recites examples that use alumina, zirconium oxide, silicon nitride as matrices along with silicon carbide ~ibers. The ~ocus o~ the '224 Patent is on a ceramic article suitable ~or electric discharge machining. In this regard, the speci~ication states that the electrical resistance of the substrate must not exceed 10 ohm-cm The publication by Kpochmal, i.e., Kpochmal, "Fiber Rein~orced Ceramics: A Review and Assessment o~
their Potential", United States Air Foree Technieal Report AFML-TR-67-207 (1967), pages 9-16, mentions ceramics (with ~iber rein~oreement) having a H~C or ZrC
matrix. The ~ilaments include tungsten, molybdenum, tantalum, boron, carbon, silicon carbide, boron carbide, and alumina.
There have also been ceramic cutting tools with whisker rein~orcement. In this regard, U.S. Patent No.
4,789,277 to Rhodes et al. discloses the use o~ ceramic whiskers (the content ranges ~rom 2 volume percent to 40 volume percent) sueh as alumina, aluminum nitride, beryllia, boron earbide, graphite, silieon earbide (pre~erably), and silicon nitride in a ceramic matrix.
The ceramic matrix is pre~erably alumina, but includes alumina "doped" with up to 30~ zirconia, ha~nia and titanium carbide. The alumina remains the dominant component o~ the matrix.
Japanese Patent Application (Kokai) No. 2-116691 A~s~ HrFT
tP
CA 02236818 1998-0~ 0 ~ 2A-pertains to a coated ceramic cutting tool wherein the composition of the tool comprises 5-40 volume percent aluminum oxide, 0.5-10 volume percent oxides of Mg, Ti, Zr, Y and rare earth atoms, and the remainder selected from the carbides, nitrides, and carbonitrides of~
titanium. A part of the titanium carbide, nitride, carbonitride component may be whiskers wherein these whiskers comprise 5-45 volume percent of the entire composition. The cutting tool has a coating (either a single layer or multiple layers) applied by either chemical vapor deposition or physical vapor deposition.
Japanese Patent Application (Kokai) No. 2- 157176 pertains to a coated ceramic cutting tool wherein the composition of the tool comprises 20-50 volume percent of one or more compounds selected from the group consisting of the carbides, nitrides and carbonitrides of titanium, 0.5-10 volume percent of one or more selected ~rom the group consisting o~ the oxides of magnesium, titanium, zirconium, yttrium and rare earth atoms, and the balance being aluminum oxide. The composition further requires that 10-80 volume percent of the titanium carbides, nitrides and carbonitrides comprise whiskers. The cutting tool has a coating (either a single layer or multiple layers) applied by either chemical vapor deposition or physical vapor deposition.
PCT\US 86\00528 Patent Application to Rhodes et al. entitled HIGH DENSITY REINFORCED CERAMIC BODIES
CA 02236818 1998-0~-0~
WO97/18177 PCT~S96/15192 AND METHOD OF MAKING SAME has as its focus the pressureless sintering of whisker-reinforced ceramic bodies. This document mentions a whisker content of between 0.5 and 21 volume percent. The specific examples teach the use of an all ;nA matrix with SiC
whisker contents from 6.l volume percent to 29.2 volume percent.
U.S. Patent No. 5,059,564 to Mehrotra et al.
for an ALUMINA-TITANIUM CARBIDE-SILICON ~ARRTn~
COMPOSITION pertains to an alumina-based matrix containing a dispersion of SiC Wh; ~ke~s and a TiC
phase. The SiC whiskers comprise l.0 to less than 30 volume percent with the most preferred range being 2.5 to 20 volume percent. The TiC comprises 5 to 40 volume percent, and preferably, with up to 3 volume percent of a sintering aid residue.
U.S. Patent No. 5,427,987 to Mehrotra et al.
for a GROUP IVB BORIDE BASED ~u~ G TOOLS FOR
MA~lNl~G GROUP VIB BASED MATERIALS concerns zirconium boride, hafnium boride and especially titanium boride cutting tools. The addition of W and Co to the boride powder improves the densification of the composition.
The 1969 Air Force Report by Whitney et al.
mentions the use of a generally high content of particle reinforcement in ZrN and HfN matrices for use as cutting tools. In this 1969 Report there is no suggestion that wh; ~ke~s could reinforce these matrices.
U.S. Patent No. 5,23l,060 to Brandt teaches using wh;~ke~s of the nitride, carbides and borides of Ti, Zr, Hf, V, Nb or Ta to reinforce an oxide-based matrix such as alumina for use as a cutting tool.
U.S. Patent No. 5,439,854 to Suzuki et al.
pertains to a cutting tool that contains 40 weight percent or more of TiC, and 5 to 40 weight percent of silicon carbide whiskers (of a length equal to 20 micrometers or less). The cutting tool may also contain WO97/18177 PCT~S96/15192 up to 40 weight percent alumina, as well as sintering aids. Up to 40 weight percent of the TiC may be substituted by Ti or a Ti-based compound such as a nitride, boride, or oxide.
Table I set forth below presents certain physical properties of some prior art commercial cutting tools.
Table I
Selected Physical Properties of Certain Commercial Cutting Tools VHN (GPa) KIC~E&c) Cutting Tool HRA [18.5 kg [MPaml/2 load]
WG-300 94.6 l9.4 6.l HC6 94.6 19.4 5.1 K090 94.8 l9.l 4.7 Referring to these c ~cial cutting tools, the WG-300 cutting tool is sold by Greenleaf Corporation of Saegertown, Pennsylvania and has a ~ ition of about 25 volume percent SiC whi~k~s and the balance alumina.
The HC6 cutting tool is sold by NTK Cutting Tool Division of NGK Spark Plugs (USA), Inc. of Farmington Hills, Michigan, and has a c: _~~ition of about 70 weight percent TiC and the balance alumina. The K090 cutting tool is made by K~nA ?tal Inc. of Latrobe, Pennsylvania and has a o~ ition of about 70 volume percent al~ in~ and 30 volume percent TiC. Each of these compositions may also contain minor amounts of sintering aid.
CA 02236818 1998-0~-0~
WO97/18177PCT~S96/15192 _5_ SUMM~RY OF THE lNV~NllO~
It is an object of the invention to provide an improved ceramic cutting tool, and a composition thereof, that has whis~er reinforcement.
5It is still another object of the invention to provide an improved ceramic cutting tool, and a ition thereof. that has ceramic whisker reinforcement wherein the ceramic matrix includes about 50 volume percent of one or more of the carbides, nitrides and/or carbonitrides of titanium, hafnium molybdenum, zirconium, tantalum, niobium, vanadium and/or tungsten.
It is another object of the invention to provide an improved ceramic cutting tool, and a ~ _-~ition thereof, that has ceramic whisker reinforcement wherein the ceramic matrix includes about 50 volume percent of one or more of the carbides, nitrides and/or carbonitrides of titanium, hafnium, molybdenum, zirconium, tantalum, niobium, vanadium and/or tungsten, and optionally, the substrate further includes one or more particulates of all ;nA, silicon carbide or the borides of titanium, zirconium or hafnium.
It is still another object of the invention to provide an improved ceramic cutting tool, and a composition thereof, that has ceramic Wh i cke~
reinforcement wherein the whiskers include one of all inA, silicon carbide, or the carbides, nitrides, borides or carbonitrides of titanium, zirconium or hafnium.
~It is another object of the invention to provide an improved ceramic cutting tool, and a composition thereof, that has ceramic wh i Cke~
reinforcement wherein the ceramic matrix includes about 50 volume percent of one or more of the carbides, nitrides and/or carbonitrides of titanium, hafnium, CA 02236818 1998-0~-0~
WO 9~/18177 PCI~/US96/15192 molybdenum, zirconium, tantalum, niobium, vanadium and/or tungsten, and optionally, the substrate further includes one or more particulates of alumina, silicon carbide or the borides of titanium, zirconium or hafnium. The ceramic whiskers include one or more of ~lumina, silicon carbide, silicon nitride, boron carbide, or the carbides, nitrides, borides, or the carbonitrides of titanium, zirconium or hafnium, or the oxides of zirconium or hafnium.
In one form thereof, the invention is a composition produced by the consolidation of a blend of starting components. The composition comprises a matrix which comprises one or more of the carbides, nitrides and carbonitrides of hafnium, molybdenum, zirconium, tantalum, niobium, vanadium, titanium, L~~ Len and solid solutions thereof in an amount that is greater than 50 volume percent of the matrix. The matrix further includes sintering aid residue present from the use of one or more sintering aids as a starting component in an amount of less than or equal to 1 weight percent of the starting components. The matrix comprises between 60 and 99.8 volume percent of the composition. The c__pocition further includes ceramic w~;~k~rs uniformly dispersed throughout the matrix wherein the ceramic whiskers comprises between 0.2 and 40 volume percent of the composition.
In another form thereof, the invention is a ceramic cutting tool that comprises a rake face and a flank face. There is a cutting edge at the juncture of the rake face and the flank face. The tool includes a ceramic composition that has a matrix comprising between about 45 volume percent and less than 50 volume percent o~ titanium molybdenum carbide, and less than about 55 volume percent alumina. The matrix comprises between about 60 volume percent and about 90 volume percent of the ceramic composition. The composition further includes ceramic whiskers uniformly dispersed CA 02236818 1998-0~-0~
W097/18177 PCT~S96/15192 throughout the matrix wherein the ceramic whiske~scomprise about 2 volume percent to about 35 volume percent of the ceramic composition.
B~T~ DESCRIPTION OF THE FIGURES
The following is a brief description of the figures that comprise a part of this patent application:
FIG. l is an isometric view of a cutting insert that comprises a specific embodiment of the cutting tool of the present invention; and FIG. 2 is a scAnni ng electron microscopy (SEM) secondary electron image photomi~o~ r aph (5000X
magnification) of a hot-pressed co~po~ite in accordance with the present invention corresponding to Example 2 herein showing a polished plane perpendicular to the hot pressing axis;
FIG. 3 is a ~c~nni ng electron microscopy (SEM) secondary electron image photomi~o~ ~ph (2000X
magnification) of a hot-pressed composite in accordance with the present invention corresponding to Example 4 herein showing a polished plane perpendicular to the hot pressing axis;
FIG. 4 is a ~Anning electron microscopy (SEM) secondary electron image photomi~o~aph (2000X
~gn;fication) of a hot-pressed c- ,~site in accordance with the present invention corresponding to Example 6 herein showing a polished plane perpendicular to the hot pressing axis;
FIG. 5 is a graph of depth of cut notch wear as a function of cutting time for embodiments of the present invention as well as a prior art composition;
FIG. 6 is a graph of flan~ wear as a function of cutting time for embo~; -nts of the present invention as well as a prior art composition; and CA 022368l8 l998-05-05 W097/18177 PCT~S96/lS192 FIG. 7 is a graph of nose wear as a function of cutting time for embodiments of the present invention as well as a prior art composition.
DE~JT~n D~CRIPTION OF SPECIFIC EMBQD
The invention pertains to ceramic compositions, and especially, such ceramic compositions that include ceramic wh i ~k~ reinforcement. Generally speaking the ceramic cutting tool comprises a ceramic matrix and ceramic Wh i ~kers which reinforce the matrix.
The combination of the matrix and the Wh i ~ke~s comprises a substrate. The substrate may be coated with a hard material. Examples of such hard materials include alumina, titanium carbide, titanium nitride, titanium carbonitride, titanium aluminum nitride, cubic boron nitride and diamond and their combinations. The coating may be applied by chemical vapor deposition (CVD) tsee U.S. Patent No. 4,801,510 to Mehrotra et al.
for ALUMINA COATED SILICON CARBIDE WHISKER-ALUMINA
COMPOSITION] or physical vapor deposition (PVD) [see U.S. Patent No. 5,264,297 to Jindal et al. for PHYSICAL
VAPOR DEPOSITION OF TITANIUM NITRIDE ON A NONCONDUCTI~E
SUBSTRATE] or a scheme where some layers are applied by PVD and some layers are applied by CVD (see U. S.
Patent No. 5,232,318 to San~h~n~ et al. for COATED
~u~ G TOOLS). The substrates that have a high titani~m carbide or titanium carbonitride content, i.e., at least 25 to 30 volume percent titanium carbide or titanium carbonitride, are electrically conductive to such an extent that they are particularly suitable for PVD coating and EDM machin;ng~
The specific matrix of the present invention comprises a carbide, carbonitride and/or nitride of one or more of titanium, hafnium, molybdenum, zirconium, tantalum, niobium, vanadium and/or tungsten so that this component is about 50 volume percent or more of the matrix.
CA 02236818 1998-0~-0~
WO97/18177 PCT~S96/15192 _9_ The reason that the preferable content for the carbide, nitride, carbonitride component is over 5 volume percent of the matrix i5 that this provides for higher hardness and a higher fracture toughness. In this regard, when the carbide, nitride, carbonitride component is over 50 volume percent of the matrix, the fracture toughness is greater than or equal to 6.3 MPaml/2 KIC~ and more preferably greater than or equal to 6.6 MPaml/2 KIC~ and the hardness is greater than or equal to 94.7 Rockwell A. The combination of the high hardness and the high fracture toughness makes these combinations suitable for use as cutting tools, bearings, seal rings, wear plates and nozzles, In addition, the matrix may include particulates of silicon carbide, titanium boride, zirconium boride, chromium boride, hafnium boride, alumina, zirconium oxide, and hafnium oxide along with sintering aid residues. The preferred content of the sintering aids is less than or equal to l weight percent, and the more preferable sintering aid content is less than or equal to .5 weight percent. The preferred sintering aids include yttria, magnesia and zirconia either alone or in combination.
The matrix comprises between 60 and 99.8 volume percent of the complete ceramic cutting tool composition.
In regard to the ceramic Wh; ~k~rs, these wh;~ke~s are selected-from any of the following materials: silicon carbide, titanium carbide, titanium carbonitride, titanium nitride, titanium boride, zirconium carbide, zirconium carbonitride, zirconium nitride, zirconium boride, hafnium carbide, hafnium nitride, hafnium carbonitride, hafnium boride, alumina, silicon nitride and boron carbide. The ceramic whis~ers comprise between 0.2 and 40 volume percent of the complete ceramic cutting tool composition.
CA 02236818 1998-0~-0~
W097/18177 PCT~S96/lS192 To -Y; ;ze fracture toughness in the present invention, it is preferred that a Group IVB (titanium, hafnium or zirconium~ nitride or carbonitride-based matrix, more preferably a titanium nitride or titanium 5 carbonitride-based matrix, be reinforced with one or more whisk~s of the group consisting of A1~03, Si3N4, TiB2, SiC, TiC, and B4C. The TiC, TiB2, SiC or B4C
whiskers should provide the best fracture toughness in a titanium nitride or titanium carbonitride-based matrix.
Referring to FIG. 1 and the geometry of the specific embodiment, there is illustrated a cutting tool generally designated as 10. Cutting tool 10 has a rake face 12 and a flank face 14. The rake face and the flank face intersect to form a cutting edge 16. The specific configuration is a SNGN-453T style o~ cutting insert with a T land according to the American National Standard for Cutting Tools-Indexable Inserts-Identification System, ANSI B212.4-1986 (cutting edge preparation: .002-.004 inch x 20~ chamfer). Other ~tyles of cutting inserts and edge preparations are acceptable and are contemplated to be within the scope of this invention.
As demonstrated from the examples below, ceramic cutting tools within the above definition have excellent density, hardness and fracture toughness.
These properties provide for excellent cutting tools, especially in the high speed ma~h~ning of steels, cast irons, and nickel-base super alloys.
In ma~-h;ning applications where abrasive wear resistance is more of a concern than chemical wear resistance, a titanium carbide-based matrix is pre~erable. If, however, chemical wear resistance is more important than abrasive wear resistance, then a hafnium carbide-based or titanium carbonitride-based matrix is preferable. Chemical wear resistance may also be improved by applying a hard coating to the insert CA 02236818 1998-0~-0~
WO97/18177 PCT~S96/15192 such as, for example, titanium nitride, titanium carbonitride, titanium aluminum nitride, titanium carbide, and alumina.
For mar-h~n;ng of nickel base super alloys, or for any workpiece in which a combination of high hardness and high chemical inertness is desired, it is preferred that a titanium carbonitride (TiCX Ny) based matrix be used in which x is greater that 0 but less than 0.95 and y + x = l. More preferably, y is greater than or equal to 0.5. For x = 0, that is titanium nitride, hardness may be reduced and there may be a reaction between the titanium nitride and the SiC
whiskers during the high temperature fabrication of these materials. Therefore, y should be less than 0.95.
Another range for x and y for titanium carbonitride tTi(CXNy)] is y is less than 0.90 and greater than or equal to 0.55, and x + y = l. Still another range for x and y for titanium carbonitride [Ti(CXNy)~ is y is less than 0.75 and greater than or equal to 0.6, and x + y = l. Optionally, titanium carbonitride may be replaced by hafnium carbonitride or zirconium carbonitride.
The following examples, as described in Tables II through IV below, are exemplary of the invention and were made according to the following method. For all of the examples, the silicon carbide whiskers were ultrasonically dispersed in isopropanol for one hour.
For Examples Nos. l through 7, 9 and l0, the silicon carbide whiskers were made by Tokai Carbon Co.
of Tokyo, Japan under the designation Grade No. l. The Tokai whiskers had an average length of 20 to 50 micrometers and an average diameter of .3 to l micrometers. The crystalline structure of these Tokai SiC whiskers was mostly beta silicon carbide.
For Examples Nos. ll and 12, the silicon carbide whiskers were obtained from Advanced Composite CA 02236818 1998-0~-0~
WO97/18177 PCT~S96~15192 Materials Corporation of Greer, South Carolina under the grade designation SC-9. The SC-9 whiskers had an average length of lO to 80 micrometers and an average diameter of 0.6 micrometers. The crystalline structure of these SC-9 SiC whiskers was alpha cilicon carbide.
In regard to the method of preparation for Examples Nos. l through 7 and 9 through 12, the balance of the components were blended in a mill with isopropanol for one ho~r. The ultrasonicated silicon carbide whiskers were then blended with the blend of the balance of the components in a mill for 20 minutes.
This blend was then discharged through a 200 mesh screen, dried in a rotary evaporator, and then passed through a lO0 mesh screen. The dried blend was uniaxially hot pressed in a ~ _~rature range of 1750~C
to 1850~C at 4500 psi for 60 minutes under an argon atmosphere to essentially full density. The resulting product was ground into a SNGN-453T style of cutting insert having a T land, (cutting edge preparation of .002 to .004 inches and 20 degrees chamfer) as described above.
Tables II through IV below includes in parenthesis the identification of the supplier if there was more than one supplier of the component. The Y2O3 for all of the examples was supplied by Hermann C.
Strack Berlin GmbH & Co, KG, P O Box 1229, D-7887 Lauterburg, Baden, Germany.
In Tables II through IV the silicon carbide whiskers supplied by Tokai carry the designation "(T)".
The silicon carbide Wh i~ke~s supplied by Advanced Composite Materials Corporation carry the designation "(A)".
For some of the examples, the Al203 was supplied by Nanophase Technologies Corporation of Darien, Illinois under the designation Nanotek Al2O3 Gamma/Delta. In Tables II through IV, the designation "(N~" shows that the Al203 powder was obtained from .
CA 02236818 1998-0~-0~
WO97/18177 PCT~S96/15192 Nanophase. The Nanotek Al2O3 powder had a BET specific surface area of 56.2 square meters/gram. The Al2O3 was greater than 99.9% pure. The phases present were delta and gamma. For the example (Example No. 2) that used the Nanotek Al2O3 powder, an addition of .05 volume percent MgO was added to the blend. The Nanotek Al2O3 powder was substantially equiaxed.
The balance of the examples used Al2O3 from several lots of Al2O3 powder that were supplied by Ceralox (a division of Vista Chemical Company) under the designation HPA-0.5. In Tables II through IV the designation "(C)" shows that the Al2O3 was from Ceralox. The Ceralox powder had a BET specific surface area of l0.0 to ll.5 square meters/gram. The as-received Ceralox Al2O3 contained an addition of .05 volume percent MgO. The Ceralox Al2O3 powder was substantially equiaxed.
The TiC supplied by Biesterfeld U.S. Inc., Advanced Materials Department of New York, New York carried the designation Furukawa TiC, and had a BET
specific surface area of 8.52 square meters/gram. In Table II the designation "(F)" shows that the TiC was Furukawa TiC. The Furukawa TiC powder was substantially equiaxed.
The TiC particles supplied by the Macro Division of Ke~ ?tal Inc. under the designation Grade A had a BET specific surface area of 5.9 square meters/gram. In Table II the designation "(M)" shows that the TiC came from the Macro Division of K~nnAmetal. The Macro Division TiC powder was substantially equiaxed.
The Ti 8M~ 2C solid solution powder supplied by the Macro Division of ~nnA~?tal Inc. of Port Coquitlam, British Columbia, Canada had a BET specific surface area of 4.6 square meters/gram. The Ti 8Mo 2C
solid solution powder was substantially equiaxed.
W097/18177 PCT~S96/1S192 The titanium carbonitride powder supplied by the Macro Division of K~nnA ?tal Inc. had a BET
specific surface area of 5.2 square meters/gram. This component has a formula of TiC 7N 3. The Macro Division titanium carbonitride powder was substantially e~uiaxed.
Tables II through IV below set forth t~e compositions (and suppliers where indicated) and the hot pressing temperature. The ~ _ .sitions are set forth in volume percent of the entire composition. For those components that are a part of the matrix, the volume percentage of the matrix for that component is set forth in brackets. For all of Examples l through 7 and 9 through 12 the alumina component contained about .05 volume percent magnesia.
In addition, Tables II through IV below set forth the results of tests to ascertain the following properties of the examples: the density (grams/cc), the Rockwell A hardness, the Vickers hardness, and the fracture toughness (MPaml/2) as measured by Evans &
Charles (Evans & Charles, "Fracture Toughness Det~ ;n~tion by Indentation", J. American Ceramic Society, Vol. 59, Nos. 7-8, pages 371-372 using a 18.5 kg load).
CA 022368l8 l998-05-05 WO 97/18177 -15- PCTrUS96/15192 Table II
TiC--Al2O3--SiC ~hi~k~l- Compositions and Physical Properties of Examples Nos. 1-3, 9 and 10 Ex./Comp & Example 1 Example 2 Example 3 Example 9 Example 10 Phy~ical Propertie3 TiC 39.75~F)39,75(F)39,75(M) 40(M) 50(M3 t53] [53] [53] [62] [59 TiC 7N 3 Ti,gM~.2C
Al2~3 35(C) 35(N) 35(C)24.75(C)34,75(C) [46.7]t46.7] [46.7][37.7] [40.7]
Y2O30.25 [.3]0.25 [.3] 0.25 [.3]0.25 [.3] 0.25 [.3]
SiCw 25(T) 25(T) 25(T) 35(T) 15(T) Temp (~C) 1750 1750 1775 1800 1800 Den3ity4.1474.147 4.137 4.069 4.318 (g/cc) HRA 95.0 95.1 94.9 94.9 94.7 VHN (Gpa) 21.0 20.8 19.7 21.1 20 [18.5 kg load]
KIC (E&C) 6.3 6.3 6.6 7.2 6.7 MPaml/2 WO97/18177 PCT~Ss6/1s192 Table III
TiC 7N 3-Alumina-SiC Whisker Compositions and Physlcal Properties of Examples Nos. 4, 7, ll and 12 Ex./Comp. ~ Example 4 Ex y le 7 Example 11 Example 12 Phy~ical Propertie~
TiC _ _ TiC 7N 3 39.03 39.75 39.75 39.75 ' ' r52-5] [53] [53] [53]
Ti,8Mo,2C
A12~335.43(C)35(C) 35(C) 35(C) [47~4] E46.7] [46.7] E46.7]
Y2O30.25 [.3] 0.25 [.3]0.25 [.3] 0.25 [.3J
SiCw25.29~T)25(T) 25~A) 25(A) Temp (~C) 1800 1800 1800 1850 Denaity 4.214 4.228 4.223 4.241 (g/cc) HRA 95.0 95.0 94.8 94.9 VHN (Gpa) 20.7 21.1 19.8 20.1 [18.5 kg load]
KIC (E&C) 6.3 6.6 7.5 7.5 MPaml/2 W097/18177 PCT~S96/15192 Table IV
Ti 8Mo 2C-Alumina-SiC Whisker r, _--ites Compositions and Physical Properties of Examples Nos. 5 and 6 Ex./ Comp. & Example 5 Example 6 Physical Properties TiC -- --TiC.7N~3 ~~
Ti,8Mo,2C 34.7 [47.6] 39.75 [53]
Al2~3 38(C) [52] 35(C) [46.7]
Y203 0.27 [.4] 0.25 [.3]
SiCw 27.03(T) 25(T) Temp. (~C) 1800 1800 Density (g/cc) 4.371 4.473 HRA 95.2 95.0 VHN (Gpa) 20.7 21.3 [18.5 kg load]
KIC (E&C) 6.3 6.5 MPaml/2 CA 02236818 1998-0~-0~
WO97/18177 PCT~S96/15192 A review of the physical properties of the examples reveals that these compositions present physical properties that should make excellent cutting tools.
For example, referring to the physical properties of the composites of Table II, Examples Nos.
l through 3, 9 and lO present compositions of TiC, alumina and SiC Wh; ~ke~s. The densities for these compositions ranged from 4.069 g/cc to 4.318 g/cc. The Rockwell A hardness (HRA) ranged from 94.7 to 95.l and the Vickers Hardress ranged from l9.7 to 2l.l. The fracture toughne~s KIC (~&C) ranged from 6.3 to 7.2 MPaml/2 A c~ ~ison of Example lO with Example 9 shows that an increase in the TiC content (from 40 vol.% to 50 vol.%) and the alumina content (from 24.75 vol.% to 34.75 vol.%) coupled with a decrease in the SiC whisker content (from 35 vol.% to 15 vol.%) results in an increase in the density of the sintered composite from 4.069 g/cc to 4.318 g/cc.
Referring to all of the examples of Table II, there does not appear to be any discerni~le trend in the hardness parameters (Rockwell A and Vickers).
A comparison between Examples Nos. l and 2 shows that the coarseness of the alumina powder does not significantly impact the physical properties.
Still referring to the composites in Table II, a comparison between Example 9 and Examples Nos. l through 3 reveals that the fracture toughness (KIC) appears to significantly increase when the alumina content decreases and the silicon carbide whisker content increases. More specifically, with the TiC
content remaining the same, a decrease in alumina from about 35 vol.% to about 25 vol.% coupled with an increase in the silicon carbide wh i~ker content from about 25 vol.% to about 35 vol.% results in an increase CA 022368l8 l998-0~-0~
WO97/18177 PCT~S96/15192 in the fracture toughness (KIC) from between 6.3 and 6.6 to 7.2 MPaml/2.
A comparison of Example 9 with Example l0 reveals that fracture toughness [KIC] increases from 6.7 to 7.2 MPaml/2 when the TiC and alumina contents decrease and the SiC whisker content increases.
Referring to the physical properties of the TiC 7N.3-al- ;n~-SiC whisker composites in Table III, it becomes apparent that the use of the SC-9 silicon carbide wh;ske~s from Advanced Composite Materials Corporation provides for an increase in the fracture toughness of this TiCN-alumina-SiC whisker composite from between 6.3 and 6.6 to 7.5 MPaml/2. Although the compositions are somewhat similar, the increase in fracture toughness appears to be due to the nature of the SC-9 whickers as compared to the Tokai silicon carbide whiskers.
~ eferring to the examples (Examples Nos. 5 and 6) of Table IV that present the physical properties~0 of the Ti 8M~ 2C-alumina-SiC whisker composites, a p~ison between Examples Nos. 5 and 6 shows that a decrease of 5 volume percent in the Ti 8M~ 2C coupled with a 3 volume percent increase in the alumina and a 2 volume percent increase in the SiC whiskers does not make a significant impact on the properties of the Ti 8Mo.2C-Al2O3-SiC whisker composite.
Overall, it can be seen that the above composites in accordance with the present invention possess a combination of hardness and fracture toughness which are unequaled by the prior art cutting tool compositions shown in Table I.
Photomicrographs which are representative of examples of the compositions in accordance with the present invention are shown in FIGS. 2, 3, and 4. In FIG. 2, which corresponds to Example 2, the lightest phase is alumina, the gray phase is titanium carbide, the elongated ~or darkest) phase are silicon carbide WO97/18177 PCT~S96/15192 wh;~k~rs. In FIG. 3, which corresponds to Example 4, the lightest phase i5 also all ;nA and the darkest phase is also silicon carbide whiFk~s, however, the gray phase is titanium carbonitride. In FIG. 4, which corresponds to Example 6, the lightest and darkest phases are respectively al~ inA and silicon carbide wh;cke~s, however, the gray pha~e is titanium molybdenum carbide.
In accordance with the present invention, the compositions of Examples l, 3, 4, 6, and 7 shown in Tables II were ground into SNGN-453T indexable cutting inserts and used to machine Inconel 718 (hardness 38 Rockwell C) in a turning test under the conditions of 800 surface feet/minute speed, 0.006 inch per revolution, feed rate, and 0.050 inch depth of cut, flood coolant, and a 45 degree lead angle. The end of life criteria used was: flank wear (FW) = .030 inch;
~x; flank wear (MM) = .040 inch; nose wear (NW) =
.040 inch; depth of cut notch (DN) = .080 inch; and crater wear (CR) = .004 inch. Included in the tests were samples of WG-300 (Example No. 8) in the same insert geometry for ~ _~rison purposes. The results of these tests are shown in Table V below and in FIGS. 5, 6, and 7. Each example is identified in FIGS. 5, 6 and 7 by its identical reference numeral. These results indicate that the tools having a matrix based on titanium carbonitride or titanium molybdenum carbide had the best cutting edge life time under the above conditions. The most rapid wear -c-~ni ! and the wear ~ch~ni I which lead to failure was depth of cut notching on all the materials shown in Table V.
CA 02236818 1998-0~-0~
WO97/18177 PCT~S96/15192 Table V
Tool Life & Failure Mode for Examples Nos. l, 3, 4, 6, 7 and WG-300 Example Rep. 1 Rep. 2 ~ool Life Relative Average Tool Life ~MinuteQ) (Minutes) (Minute~) vs. WG-300 1 5.8 DN 1.5 DN 3.7 78 3 4.3 DN 1.3 DN 2.8 60 4 9.7 DN 8.8 DN 9.3 197 6 7.3 DN 6.4 DN 6.9 146~
7 4.7 DN 6.9 DN 5.8 123%
8 4.3 DN ~.1 DN 4.7 100 However, the flank wear resistance of the present invention was less than that of the prior art grade tested. It is believed that flank wear resistance may be improved by increasing the nitrogen content of the titanium carbonitride forming the matrix or increasing the molybdenum content of the titanium molybdenum carbide used in the matrix. Flank wear resistance of the present invention may also be improved by applying a hard coating to the cutting insert composed of compositions in accordance with the present invention.
Preferred hard coatings include titanium nitride, titanium carbonitride, titanium aluminum nitride, and al~ coatings applied by PVD and/or CVD techni ~ues.
The flank wear resistance of the prior art grade tested (Example-No. 8/ WG-300) appeared to be better than Examples Nos. l, 3, 4, 6 and 7. This may be due to the greater alumina content in the prior art grade. More specifically, the prior art grade (Example No. 8/ WG-300) has an alumina content of about 75 volume percent as compared with about 35 to 40 volume percent for Examples Nos. l, 3, 4, 6 and 7. The flank wear resistance of the present invention may be improved by the use of greater amounts of alumina or by decreasing the amount of silicon carbide whiskers present and increasing one or more of the matrix phases, e.g., titanium carbonitride or alumina.
All applications, patents and other ~o~ -nts referred to herein are hereby incorporated by re~erence herein.
Other embodiments of the invention will be apparent to those skilled in the art from a consideration of the specification or practice of the invention disclosed herein. It is intended that the specification and examples be considered as illustrative only, with the true scope and spirit of the invention being indicated by the following claims.
~{I8RER ~ ZD~TC ~ lNG TOOL
AND COIIPO~ITION ~ K~ G~
BACKGROUND OF THE lN v~;N~ oN
The present invention pertains to a ceramic cutting tool, and a composition thereof, that has Whi sk~r reinfo,~ ent. More specifically, the invention pertains to a ceramic cutting tool, and a composition thereof, that has ceramic whisker reinforcement wherein at least 50 volume percent of the ceramic matrix comprises a carbide, nitride and/or carbonitride of titanium, hafnium, molybdenum, zirconium, tantalum, niobium, vanadium and/or Lun~en.
In the past, there have been ceramic bodies with Wh i ~k~r reinforcement such as that disclosed in U.S. Patent No. 4,543,345 to Wei. The Wei Patent discloses an alumina matrix with silicon carbide whicker reinforcement, a boron carbide matrix with silicon carbide whiskers, and a mullite matrix with silicon carbide whiskers. According to the Wei patent, the incorporation of silicon carbide whiskers increased the fracture toughness of the substrate.
Japanese Publication No. 63-10758 to Yamagawa et al. pertains to a ceramic composite that comprises ~ alumina as its main component. The balance comprises between 5 to 40 weight TiC and 2 to 40 weight percent silicon carbide whiskers. The combined amount of titanium carbide and silicon carbide whiskers cannot ce~ 50 weight percent, i.e., it is 50 weight percent or less. This document also mentions that there can be up to 10 weight percent of an oxide, carbide or nitride CA 022368l8 l998-0~-0~
o~ aluminum, silicon and the Group IVa, Va and VIa elements.
U.S. Patent No. 4,507,224 to Toibana et al. makes general re~erence to certain nitrides and carbides as suitable matrix material, along with electroconduetive powder, ~or SiC ~iber rein~orcement. The SiC ~ibers are present in an amount between 5 and 50 weight percent.
The '224 patent makes specific re~erence to matrices o~
silicon nitride, aluminum nitride, boron nitride, silicon carbide, boron carbide, and titanium carbide.
The '224 Patent recites examples that use alumina, zirconium oxide, silicon nitride as matrices along with silicon carbide ~ibers. The ~ocus o~ the '224 Patent is on a ceramic article suitable ~or electric discharge machining. In this regard, the speci~ication states that the electrical resistance of the substrate must not exceed 10 ohm-cm The publication by Kpochmal, i.e., Kpochmal, "Fiber Rein~orced Ceramics: A Review and Assessment o~
their Potential", United States Air Foree Technieal Report AFML-TR-67-207 (1967), pages 9-16, mentions ceramics (with ~iber rein~oreement) having a H~C or ZrC
matrix. The ~ilaments include tungsten, molybdenum, tantalum, boron, carbon, silicon carbide, boron carbide, and alumina.
There have also been ceramic cutting tools with whisker rein~orcement. In this regard, U.S. Patent No.
4,789,277 to Rhodes et al. discloses the use o~ ceramic whiskers (the content ranges ~rom 2 volume percent to 40 volume percent) sueh as alumina, aluminum nitride, beryllia, boron earbide, graphite, silieon earbide (pre~erably), and silicon nitride in a ceramic matrix.
The ceramic matrix is pre~erably alumina, but includes alumina "doped" with up to 30~ zirconia, ha~nia and titanium carbide. The alumina remains the dominant component o~ the matrix.
Japanese Patent Application (Kokai) No. 2-116691 A~s~ HrFT
tP
CA 02236818 1998-0~ 0 ~ 2A-pertains to a coated ceramic cutting tool wherein the composition of the tool comprises 5-40 volume percent aluminum oxide, 0.5-10 volume percent oxides of Mg, Ti, Zr, Y and rare earth atoms, and the remainder selected from the carbides, nitrides, and carbonitrides of~
titanium. A part of the titanium carbide, nitride, carbonitride component may be whiskers wherein these whiskers comprise 5-45 volume percent of the entire composition. The cutting tool has a coating (either a single layer or multiple layers) applied by either chemical vapor deposition or physical vapor deposition.
Japanese Patent Application (Kokai) No. 2- 157176 pertains to a coated ceramic cutting tool wherein the composition of the tool comprises 20-50 volume percent of one or more compounds selected from the group consisting of the carbides, nitrides and carbonitrides of titanium, 0.5-10 volume percent of one or more selected ~rom the group consisting o~ the oxides of magnesium, titanium, zirconium, yttrium and rare earth atoms, and the balance being aluminum oxide. The composition further requires that 10-80 volume percent of the titanium carbides, nitrides and carbonitrides comprise whiskers. The cutting tool has a coating (either a single layer or multiple layers) applied by either chemical vapor deposition or physical vapor deposition.
PCT\US 86\00528 Patent Application to Rhodes et al. entitled HIGH DENSITY REINFORCED CERAMIC BODIES
CA 02236818 1998-0~-0~
WO97/18177 PCT~S96/15192 AND METHOD OF MAKING SAME has as its focus the pressureless sintering of whisker-reinforced ceramic bodies. This document mentions a whisker content of between 0.5 and 21 volume percent. The specific examples teach the use of an all ;nA matrix with SiC
whisker contents from 6.l volume percent to 29.2 volume percent.
U.S. Patent No. 5,059,564 to Mehrotra et al.
for an ALUMINA-TITANIUM CARBIDE-SILICON ~ARRTn~
COMPOSITION pertains to an alumina-based matrix containing a dispersion of SiC Wh; ~ke~s and a TiC
phase. The SiC whiskers comprise l.0 to less than 30 volume percent with the most preferred range being 2.5 to 20 volume percent. The TiC comprises 5 to 40 volume percent, and preferably, with up to 3 volume percent of a sintering aid residue.
U.S. Patent No. 5,427,987 to Mehrotra et al.
for a GROUP IVB BORIDE BASED ~u~ G TOOLS FOR
MA~lNl~G GROUP VIB BASED MATERIALS concerns zirconium boride, hafnium boride and especially titanium boride cutting tools. The addition of W and Co to the boride powder improves the densification of the composition.
The 1969 Air Force Report by Whitney et al.
mentions the use of a generally high content of particle reinforcement in ZrN and HfN matrices for use as cutting tools. In this 1969 Report there is no suggestion that wh; ~ke~s could reinforce these matrices.
U.S. Patent No. 5,23l,060 to Brandt teaches using wh;~ke~s of the nitride, carbides and borides of Ti, Zr, Hf, V, Nb or Ta to reinforce an oxide-based matrix such as alumina for use as a cutting tool.
U.S. Patent No. 5,439,854 to Suzuki et al.
pertains to a cutting tool that contains 40 weight percent or more of TiC, and 5 to 40 weight percent of silicon carbide whiskers (of a length equal to 20 micrometers or less). The cutting tool may also contain WO97/18177 PCT~S96/15192 up to 40 weight percent alumina, as well as sintering aids. Up to 40 weight percent of the TiC may be substituted by Ti or a Ti-based compound such as a nitride, boride, or oxide.
Table I set forth below presents certain physical properties of some prior art commercial cutting tools.
Table I
Selected Physical Properties of Certain Commercial Cutting Tools VHN (GPa) KIC~E&c) Cutting Tool HRA [18.5 kg [MPaml/2 load]
WG-300 94.6 l9.4 6.l HC6 94.6 19.4 5.1 K090 94.8 l9.l 4.7 Referring to these c ~cial cutting tools, the WG-300 cutting tool is sold by Greenleaf Corporation of Saegertown, Pennsylvania and has a ~ ition of about 25 volume percent SiC whi~k~s and the balance alumina.
The HC6 cutting tool is sold by NTK Cutting Tool Division of NGK Spark Plugs (USA), Inc. of Farmington Hills, Michigan, and has a c: _~~ition of about 70 weight percent TiC and the balance alumina. The K090 cutting tool is made by K~nA ?tal Inc. of Latrobe, Pennsylvania and has a o~ ition of about 70 volume percent al~ in~ and 30 volume percent TiC. Each of these compositions may also contain minor amounts of sintering aid.
CA 02236818 1998-0~-0~
WO97/18177PCT~S96/15192 _5_ SUMM~RY OF THE lNV~NllO~
It is an object of the invention to provide an improved ceramic cutting tool, and a composition thereof, that has whis~er reinforcement.
5It is still another object of the invention to provide an improved ceramic cutting tool, and a ition thereof. that has ceramic whisker reinforcement wherein the ceramic matrix includes about 50 volume percent of one or more of the carbides, nitrides and/or carbonitrides of titanium, hafnium molybdenum, zirconium, tantalum, niobium, vanadium and/or tungsten.
It is another object of the invention to provide an improved ceramic cutting tool, and a ~ _-~ition thereof, that has ceramic whisker reinforcement wherein the ceramic matrix includes about 50 volume percent of one or more of the carbides, nitrides and/or carbonitrides of titanium, hafnium, molybdenum, zirconium, tantalum, niobium, vanadium and/or tungsten, and optionally, the substrate further includes one or more particulates of all ;nA, silicon carbide or the borides of titanium, zirconium or hafnium.
It is still another object of the invention to provide an improved ceramic cutting tool, and a composition thereof, that has ceramic Wh i cke~
reinforcement wherein the whiskers include one of all inA, silicon carbide, or the carbides, nitrides, borides or carbonitrides of titanium, zirconium or hafnium.
~It is another object of the invention to provide an improved ceramic cutting tool, and a composition thereof, that has ceramic wh i Cke~
reinforcement wherein the ceramic matrix includes about 50 volume percent of one or more of the carbides, nitrides and/or carbonitrides of titanium, hafnium, CA 02236818 1998-0~-0~
WO 9~/18177 PCI~/US96/15192 molybdenum, zirconium, tantalum, niobium, vanadium and/or tungsten, and optionally, the substrate further includes one or more particulates of alumina, silicon carbide or the borides of titanium, zirconium or hafnium. The ceramic whiskers include one or more of ~lumina, silicon carbide, silicon nitride, boron carbide, or the carbides, nitrides, borides, or the carbonitrides of titanium, zirconium or hafnium, or the oxides of zirconium or hafnium.
In one form thereof, the invention is a composition produced by the consolidation of a blend of starting components. The composition comprises a matrix which comprises one or more of the carbides, nitrides and carbonitrides of hafnium, molybdenum, zirconium, tantalum, niobium, vanadium, titanium, L~~ Len and solid solutions thereof in an amount that is greater than 50 volume percent of the matrix. The matrix further includes sintering aid residue present from the use of one or more sintering aids as a starting component in an amount of less than or equal to 1 weight percent of the starting components. The matrix comprises between 60 and 99.8 volume percent of the composition. The c__pocition further includes ceramic w~;~k~rs uniformly dispersed throughout the matrix wherein the ceramic whiskers comprises between 0.2 and 40 volume percent of the composition.
In another form thereof, the invention is a ceramic cutting tool that comprises a rake face and a flank face. There is a cutting edge at the juncture of the rake face and the flank face. The tool includes a ceramic composition that has a matrix comprising between about 45 volume percent and less than 50 volume percent o~ titanium molybdenum carbide, and less than about 55 volume percent alumina. The matrix comprises between about 60 volume percent and about 90 volume percent of the ceramic composition. The composition further includes ceramic whiskers uniformly dispersed CA 02236818 1998-0~-0~
W097/18177 PCT~S96/15192 throughout the matrix wherein the ceramic whiske~scomprise about 2 volume percent to about 35 volume percent of the ceramic composition.
B~T~ DESCRIPTION OF THE FIGURES
The following is a brief description of the figures that comprise a part of this patent application:
FIG. l is an isometric view of a cutting insert that comprises a specific embodiment of the cutting tool of the present invention; and FIG. 2 is a scAnni ng electron microscopy (SEM) secondary electron image photomi~o~ r aph (5000X
magnification) of a hot-pressed co~po~ite in accordance with the present invention corresponding to Example 2 herein showing a polished plane perpendicular to the hot pressing axis;
FIG. 3 is a ~c~nni ng electron microscopy (SEM) secondary electron image photomi~o~ ~ph (2000X
magnification) of a hot-pressed composite in accordance with the present invention corresponding to Example 4 herein showing a polished plane perpendicular to the hot pressing axis;
FIG. 4 is a ~Anning electron microscopy (SEM) secondary electron image photomi~o~aph (2000X
~gn;fication) of a hot-pressed c- ,~site in accordance with the present invention corresponding to Example 6 herein showing a polished plane perpendicular to the hot pressing axis;
FIG. 5 is a graph of depth of cut notch wear as a function of cutting time for embodiments of the present invention as well as a prior art composition;
FIG. 6 is a graph of flan~ wear as a function of cutting time for embo~; -nts of the present invention as well as a prior art composition; and CA 022368l8 l998-05-05 W097/18177 PCT~S96/lS192 FIG. 7 is a graph of nose wear as a function of cutting time for embodiments of the present invention as well as a prior art composition.
DE~JT~n D~CRIPTION OF SPECIFIC EMBQD
The invention pertains to ceramic compositions, and especially, such ceramic compositions that include ceramic wh i ~k~ reinforcement. Generally speaking the ceramic cutting tool comprises a ceramic matrix and ceramic Wh i ~kers which reinforce the matrix.
The combination of the matrix and the Wh i ~ke~s comprises a substrate. The substrate may be coated with a hard material. Examples of such hard materials include alumina, titanium carbide, titanium nitride, titanium carbonitride, titanium aluminum nitride, cubic boron nitride and diamond and their combinations. The coating may be applied by chemical vapor deposition (CVD) tsee U.S. Patent No. 4,801,510 to Mehrotra et al.
for ALUMINA COATED SILICON CARBIDE WHISKER-ALUMINA
COMPOSITION] or physical vapor deposition (PVD) [see U.S. Patent No. 5,264,297 to Jindal et al. for PHYSICAL
VAPOR DEPOSITION OF TITANIUM NITRIDE ON A NONCONDUCTI~E
SUBSTRATE] or a scheme where some layers are applied by PVD and some layers are applied by CVD (see U. S.
Patent No. 5,232,318 to San~h~n~ et al. for COATED
~u~ G TOOLS). The substrates that have a high titani~m carbide or titanium carbonitride content, i.e., at least 25 to 30 volume percent titanium carbide or titanium carbonitride, are electrically conductive to such an extent that they are particularly suitable for PVD coating and EDM machin;ng~
The specific matrix of the present invention comprises a carbide, carbonitride and/or nitride of one or more of titanium, hafnium, molybdenum, zirconium, tantalum, niobium, vanadium and/or tungsten so that this component is about 50 volume percent or more of the matrix.
CA 02236818 1998-0~-0~
WO97/18177 PCT~S96/15192 _9_ The reason that the preferable content for the carbide, nitride, carbonitride component is over 5 volume percent of the matrix i5 that this provides for higher hardness and a higher fracture toughness. In this regard, when the carbide, nitride, carbonitride component is over 50 volume percent of the matrix, the fracture toughness is greater than or equal to 6.3 MPaml/2 KIC~ and more preferably greater than or equal to 6.6 MPaml/2 KIC~ and the hardness is greater than or equal to 94.7 Rockwell A. The combination of the high hardness and the high fracture toughness makes these combinations suitable for use as cutting tools, bearings, seal rings, wear plates and nozzles, In addition, the matrix may include particulates of silicon carbide, titanium boride, zirconium boride, chromium boride, hafnium boride, alumina, zirconium oxide, and hafnium oxide along with sintering aid residues. The preferred content of the sintering aids is less than or equal to l weight percent, and the more preferable sintering aid content is less than or equal to .5 weight percent. The preferred sintering aids include yttria, magnesia and zirconia either alone or in combination.
The matrix comprises between 60 and 99.8 volume percent of the complete ceramic cutting tool composition.
In regard to the ceramic Wh; ~k~rs, these wh;~ke~s are selected-from any of the following materials: silicon carbide, titanium carbide, titanium carbonitride, titanium nitride, titanium boride, zirconium carbide, zirconium carbonitride, zirconium nitride, zirconium boride, hafnium carbide, hafnium nitride, hafnium carbonitride, hafnium boride, alumina, silicon nitride and boron carbide. The ceramic whis~ers comprise between 0.2 and 40 volume percent of the complete ceramic cutting tool composition.
CA 02236818 1998-0~-0~
W097/18177 PCT~S96/lS192 To -Y; ;ze fracture toughness in the present invention, it is preferred that a Group IVB (titanium, hafnium or zirconium~ nitride or carbonitride-based matrix, more preferably a titanium nitride or titanium 5 carbonitride-based matrix, be reinforced with one or more whisk~s of the group consisting of A1~03, Si3N4, TiB2, SiC, TiC, and B4C. The TiC, TiB2, SiC or B4C
whiskers should provide the best fracture toughness in a titanium nitride or titanium carbonitride-based matrix.
Referring to FIG. 1 and the geometry of the specific embodiment, there is illustrated a cutting tool generally designated as 10. Cutting tool 10 has a rake face 12 and a flank face 14. The rake face and the flank face intersect to form a cutting edge 16. The specific configuration is a SNGN-453T style o~ cutting insert with a T land according to the American National Standard for Cutting Tools-Indexable Inserts-Identification System, ANSI B212.4-1986 (cutting edge preparation: .002-.004 inch x 20~ chamfer). Other ~tyles of cutting inserts and edge preparations are acceptable and are contemplated to be within the scope of this invention.
As demonstrated from the examples below, ceramic cutting tools within the above definition have excellent density, hardness and fracture toughness.
These properties provide for excellent cutting tools, especially in the high speed ma~h~ning of steels, cast irons, and nickel-base super alloys.
In ma~-h;ning applications where abrasive wear resistance is more of a concern than chemical wear resistance, a titanium carbide-based matrix is pre~erable. If, however, chemical wear resistance is more important than abrasive wear resistance, then a hafnium carbide-based or titanium carbonitride-based matrix is preferable. Chemical wear resistance may also be improved by applying a hard coating to the insert CA 02236818 1998-0~-0~
WO97/18177 PCT~S96/15192 such as, for example, titanium nitride, titanium carbonitride, titanium aluminum nitride, titanium carbide, and alumina.
For mar-h~n;ng of nickel base super alloys, or for any workpiece in which a combination of high hardness and high chemical inertness is desired, it is preferred that a titanium carbonitride (TiCX Ny) based matrix be used in which x is greater that 0 but less than 0.95 and y + x = l. More preferably, y is greater than or equal to 0.5. For x = 0, that is titanium nitride, hardness may be reduced and there may be a reaction between the titanium nitride and the SiC
whiskers during the high temperature fabrication of these materials. Therefore, y should be less than 0.95.
Another range for x and y for titanium carbonitride tTi(CXNy)] is y is less than 0.90 and greater than or equal to 0.55, and x + y = l. Still another range for x and y for titanium carbonitride [Ti(CXNy)~ is y is less than 0.75 and greater than or equal to 0.6, and x + y = l. Optionally, titanium carbonitride may be replaced by hafnium carbonitride or zirconium carbonitride.
The following examples, as described in Tables II through IV below, are exemplary of the invention and were made according to the following method. For all of the examples, the silicon carbide whiskers were ultrasonically dispersed in isopropanol for one hour.
For Examples Nos. l through 7, 9 and l0, the silicon carbide whiskers were made by Tokai Carbon Co.
of Tokyo, Japan under the designation Grade No. l. The Tokai whiskers had an average length of 20 to 50 micrometers and an average diameter of .3 to l micrometers. The crystalline structure of these Tokai SiC whiskers was mostly beta silicon carbide.
For Examples Nos. ll and 12, the silicon carbide whiskers were obtained from Advanced Composite CA 02236818 1998-0~-0~
WO97/18177 PCT~S96~15192 Materials Corporation of Greer, South Carolina under the grade designation SC-9. The SC-9 whiskers had an average length of lO to 80 micrometers and an average diameter of 0.6 micrometers. The crystalline structure of these SC-9 SiC whiskers was alpha cilicon carbide.
In regard to the method of preparation for Examples Nos. l through 7 and 9 through 12, the balance of the components were blended in a mill with isopropanol for one ho~r. The ultrasonicated silicon carbide whiskers were then blended with the blend of the balance of the components in a mill for 20 minutes.
This blend was then discharged through a 200 mesh screen, dried in a rotary evaporator, and then passed through a lO0 mesh screen. The dried blend was uniaxially hot pressed in a ~ _~rature range of 1750~C
to 1850~C at 4500 psi for 60 minutes under an argon atmosphere to essentially full density. The resulting product was ground into a SNGN-453T style of cutting insert having a T land, (cutting edge preparation of .002 to .004 inches and 20 degrees chamfer) as described above.
Tables II through IV below includes in parenthesis the identification of the supplier if there was more than one supplier of the component. The Y2O3 for all of the examples was supplied by Hermann C.
Strack Berlin GmbH & Co, KG, P O Box 1229, D-7887 Lauterburg, Baden, Germany.
In Tables II through IV the silicon carbide whiskers supplied by Tokai carry the designation "(T)".
The silicon carbide Wh i~ke~s supplied by Advanced Composite Materials Corporation carry the designation "(A)".
For some of the examples, the Al203 was supplied by Nanophase Technologies Corporation of Darien, Illinois under the designation Nanotek Al2O3 Gamma/Delta. In Tables II through IV, the designation "(N~" shows that the Al203 powder was obtained from .
CA 02236818 1998-0~-0~
WO97/18177 PCT~S96/15192 Nanophase. The Nanotek Al2O3 powder had a BET specific surface area of 56.2 square meters/gram. The Al2O3 was greater than 99.9% pure. The phases present were delta and gamma. For the example (Example No. 2) that used the Nanotek Al2O3 powder, an addition of .05 volume percent MgO was added to the blend. The Nanotek Al2O3 powder was substantially equiaxed.
The balance of the examples used Al2O3 from several lots of Al2O3 powder that were supplied by Ceralox (a division of Vista Chemical Company) under the designation HPA-0.5. In Tables II through IV the designation "(C)" shows that the Al2O3 was from Ceralox. The Ceralox powder had a BET specific surface area of l0.0 to ll.5 square meters/gram. The as-received Ceralox Al2O3 contained an addition of .05 volume percent MgO. The Ceralox Al2O3 powder was substantially equiaxed.
The TiC supplied by Biesterfeld U.S. Inc., Advanced Materials Department of New York, New York carried the designation Furukawa TiC, and had a BET
specific surface area of 8.52 square meters/gram. In Table II the designation "(F)" shows that the TiC was Furukawa TiC. The Furukawa TiC powder was substantially equiaxed.
The TiC particles supplied by the Macro Division of Ke~ ?tal Inc. under the designation Grade A had a BET specific surface area of 5.9 square meters/gram. In Table II the designation "(M)" shows that the TiC came from the Macro Division of K~nnAmetal. The Macro Division TiC powder was substantially equiaxed.
The Ti 8M~ 2C solid solution powder supplied by the Macro Division of ~nnA~?tal Inc. of Port Coquitlam, British Columbia, Canada had a BET specific surface area of 4.6 square meters/gram. The Ti 8Mo 2C
solid solution powder was substantially equiaxed.
W097/18177 PCT~S96/1S192 The titanium carbonitride powder supplied by the Macro Division of K~nnA ?tal Inc. had a BET
specific surface area of 5.2 square meters/gram. This component has a formula of TiC 7N 3. The Macro Division titanium carbonitride powder was substantially e~uiaxed.
Tables II through IV below set forth t~e compositions (and suppliers where indicated) and the hot pressing temperature. The ~ _ .sitions are set forth in volume percent of the entire composition. For those components that are a part of the matrix, the volume percentage of the matrix for that component is set forth in brackets. For all of Examples l through 7 and 9 through 12 the alumina component contained about .05 volume percent magnesia.
In addition, Tables II through IV below set forth the results of tests to ascertain the following properties of the examples: the density (grams/cc), the Rockwell A hardness, the Vickers hardness, and the fracture toughness (MPaml/2) as measured by Evans &
Charles (Evans & Charles, "Fracture Toughness Det~ ;n~tion by Indentation", J. American Ceramic Society, Vol. 59, Nos. 7-8, pages 371-372 using a 18.5 kg load).
CA 022368l8 l998-05-05 WO 97/18177 -15- PCTrUS96/15192 Table II
TiC--Al2O3--SiC ~hi~k~l- Compositions and Physical Properties of Examples Nos. 1-3, 9 and 10 Ex./Comp & Example 1 Example 2 Example 3 Example 9 Example 10 Phy~ical Propertie3 TiC 39.75~F)39,75(F)39,75(M) 40(M) 50(M3 t53] [53] [53] [62] [59 TiC 7N 3 Ti,gM~.2C
Al2~3 35(C) 35(N) 35(C)24.75(C)34,75(C) [46.7]t46.7] [46.7][37.7] [40.7]
Y2O30.25 [.3]0.25 [.3] 0.25 [.3]0.25 [.3] 0.25 [.3]
SiCw 25(T) 25(T) 25(T) 35(T) 15(T) Temp (~C) 1750 1750 1775 1800 1800 Den3ity4.1474.147 4.137 4.069 4.318 (g/cc) HRA 95.0 95.1 94.9 94.9 94.7 VHN (Gpa) 21.0 20.8 19.7 21.1 20 [18.5 kg load]
KIC (E&C) 6.3 6.3 6.6 7.2 6.7 MPaml/2 WO97/18177 PCT~Ss6/1s192 Table III
TiC 7N 3-Alumina-SiC Whisker Compositions and Physlcal Properties of Examples Nos. 4, 7, ll and 12 Ex./Comp. ~ Example 4 Ex y le 7 Example 11 Example 12 Phy~ical Propertie~
TiC _ _ TiC 7N 3 39.03 39.75 39.75 39.75 ' ' r52-5] [53] [53] [53]
Ti,8Mo,2C
A12~335.43(C)35(C) 35(C) 35(C) [47~4] E46.7] [46.7] E46.7]
Y2O30.25 [.3] 0.25 [.3]0.25 [.3] 0.25 [.3J
SiCw25.29~T)25(T) 25~A) 25(A) Temp (~C) 1800 1800 1800 1850 Denaity 4.214 4.228 4.223 4.241 (g/cc) HRA 95.0 95.0 94.8 94.9 VHN (Gpa) 20.7 21.1 19.8 20.1 [18.5 kg load]
KIC (E&C) 6.3 6.6 7.5 7.5 MPaml/2 W097/18177 PCT~S96/15192 Table IV
Ti 8Mo 2C-Alumina-SiC Whisker r, _--ites Compositions and Physical Properties of Examples Nos. 5 and 6 Ex./ Comp. & Example 5 Example 6 Physical Properties TiC -- --TiC.7N~3 ~~
Ti,8Mo,2C 34.7 [47.6] 39.75 [53]
Al2~3 38(C) [52] 35(C) [46.7]
Y203 0.27 [.4] 0.25 [.3]
SiCw 27.03(T) 25(T) Temp. (~C) 1800 1800 Density (g/cc) 4.371 4.473 HRA 95.2 95.0 VHN (Gpa) 20.7 21.3 [18.5 kg load]
KIC (E&C) 6.3 6.5 MPaml/2 CA 02236818 1998-0~-0~
WO97/18177 PCT~S96/15192 A review of the physical properties of the examples reveals that these compositions present physical properties that should make excellent cutting tools.
For example, referring to the physical properties of the composites of Table II, Examples Nos.
l through 3, 9 and lO present compositions of TiC, alumina and SiC Wh; ~ke~s. The densities for these compositions ranged from 4.069 g/cc to 4.318 g/cc. The Rockwell A hardness (HRA) ranged from 94.7 to 95.l and the Vickers Hardress ranged from l9.7 to 2l.l. The fracture toughne~s KIC (~&C) ranged from 6.3 to 7.2 MPaml/2 A c~ ~ison of Example lO with Example 9 shows that an increase in the TiC content (from 40 vol.% to 50 vol.%) and the alumina content (from 24.75 vol.% to 34.75 vol.%) coupled with a decrease in the SiC whisker content (from 35 vol.% to 15 vol.%) results in an increase in the density of the sintered composite from 4.069 g/cc to 4.318 g/cc.
Referring to all of the examples of Table II, there does not appear to be any discerni~le trend in the hardness parameters (Rockwell A and Vickers).
A comparison between Examples Nos. l and 2 shows that the coarseness of the alumina powder does not significantly impact the physical properties.
Still referring to the composites in Table II, a comparison between Example 9 and Examples Nos. l through 3 reveals that the fracture toughness (KIC) appears to significantly increase when the alumina content decreases and the silicon carbide whisker content increases. More specifically, with the TiC
content remaining the same, a decrease in alumina from about 35 vol.% to about 25 vol.% coupled with an increase in the silicon carbide wh i~ker content from about 25 vol.% to about 35 vol.% results in an increase CA 022368l8 l998-0~-0~
WO97/18177 PCT~S96/15192 in the fracture toughness (KIC) from between 6.3 and 6.6 to 7.2 MPaml/2.
A comparison of Example 9 with Example l0 reveals that fracture toughness [KIC] increases from 6.7 to 7.2 MPaml/2 when the TiC and alumina contents decrease and the SiC whisker content increases.
Referring to the physical properties of the TiC 7N.3-al- ;n~-SiC whisker composites in Table III, it becomes apparent that the use of the SC-9 silicon carbide wh;ske~s from Advanced Composite Materials Corporation provides for an increase in the fracture toughness of this TiCN-alumina-SiC whisker composite from between 6.3 and 6.6 to 7.5 MPaml/2. Although the compositions are somewhat similar, the increase in fracture toughness appears to be due to the nature of the SC-9 whickers as compared to the Tokai silicon carbide whiskers.
~ eferring to the examples (Examples Nos. 5 and 6) of Table IV that present the physical properties~0 of the Ti 8M~ 2C-alumina-SiC whisker composites, a p~ison between Examples Nos. 5 and 6 shows that a decrease of 5 volume percent in the Ti 8M~ 2C coupled with a 3 volume percent increase in the alumina and a 2 volume percent increase in the SiC whiskers does not make a significant impact on the properties of the Ti 8Mo.2C-Al2O3-SiC whisker composite.
Overall, it can be seen that the above composites in accordance with the present invention possess a combination of hardness and fracture toughness which are unequaled by the prior art cutting tool compositions shown in Table I.
Photomicrographs which are representative of examples of the compositions in accordance with the present invention are shown in FIGS. 2, 3, and 4. In FIG. 2, which corresponds to Example 2, the lightest phase is alumina, the gray phase is titanium carbide, the elongated ~or darkest) phase are silicon carbide WO97/18177 PCT~S96/15192 wh;~k~rs. In FIG. 3, which corresponds to Example 4, the lightest phase i5 also all ;nA and the darkest phase is also silicon carbide whiFk~s, however, the gray phase is titanium carbonitride. In FIG. 4, which corresponds to Example 6, the lightest and darkest phases are respectively al~ inA and silicon carbide wh;cke~s, however, the gray pha~e is titanium molybdenum carbide.
In accordance with the present invention, the compositions of Examples l, 3, 4, 6, and 7 shown in Tables II were ground into SNGN-453T indexable cutting inserts and used to machine Inconel 718 (hardness 38 Rockwell C) in a turning test under the conditions of 800 surface feet/minute speed, 0.006 inch per revolution, feed rate, and 0.050 inch depth of cut, flood coolant, and a 45 degree lead angle. The end of life criteria used was: flank wear (FW) = .030 inch;
~x; flank wear (MM) = .040 inch; nose wear (NW) =
.040 inch; depth of cut notch (DN) = .080 inch; and crater wear (CR) = .004 inch. Included in the tests were samples of WG-300 (Example No. 8) in the same insert geometry for ~ _~rison purposes. The results of these tests are shown in Table V below and in FIGS. 5, 6, and 7. Each example is identified in FIGS. 5, 6 and 7 by its identical reference numeral. These results indicate that the tools having a matrix based on titanium carbonitride or titanium molybdenum carbide had the best cutting edge life time under the above conditions. The most rapid wear -c-~ni ! and the wear ~ch~ni I which lead to failure was depth of cut notching on all the materials shown in Table V.
CA 02236818 1998-0~-0~
WO97/18177 PCT~S96/15192 Table V
Tool Life & Failure Mode for Examples Nos. l, 3, 4, 6, 7 and WG-300 Example Rep. 1 Rep. 2 ~ool Life Relative Average Tool Life ~MinuteQ) (Minutes) (Minute~) vs. WG-300 1 5.8 DN 1.5 DN 3.7 78 3 4.3 DN 1.3 DN 2.8 60 4 9.7 DN 8.8 DN 9.3 197 6 7.3 DN 6.4 DN 6.9 146~
7 4.7 DN 6.9 DN 5.8 123%
8 4.3 DN ~.1 DN 4.7 100 However, the flank wear resistance of the present invention was less than that of the prior art grade tested. It is believed that flank wear resistance may be improved by increasing the nitrogen content of the titanium carbonitride forming the matrix or increasing the molybdenum content of the titanium molybdenum carbide used in the matrix. Flank wear resistance of the present invention may also be improved by applying a hard coating to the cutting insert composed of compositions in accordance with the present invention.
Preferred hard coatings include titanium nitride, titanium carbonitride, titanium aluminum nitride, and al~ coatings applied by PVD and/or CVD techni ~ues.
The flank wear resistance of the prior art grade tested (Example-No. 8/ WG-300) appeared to be better than Examples Nos. l, 3, 4, 6 and 7. This may be due to the greater alumina content in the prior art grade. More specifically, the prior art grade (Example No. 8/ WG-300) has an alumina content of about 75 volume percent as compared with about 35 to 40 volume percent for Examples Nos. l, 3, 4, 6 and 7. The flank wear resistance of the present invention may be improved by the use of greater amounts of alumina or by decreasing the amount of silicon carbide whiskers present and increasing one or more of the matrix phases, e.g., titanium carbonitride or alumina.
All applications, patents and other ~o~ -nts referred to herein are hereby incorporated by re~erence herein.
Other embodiments of the invention will be apparent to those skilled in the art from a consideration of the specification or practice of the invention disclosed herein. It is intended that the specification and examples be considered as illustrative only, with the true scope and spirit of the invention being indicated by the following claims.
Claims (27)
1. A ceramic cutting tool comprising:
a rake face; and a flank face, a cutting edge at the juncture of the rake face and the flank face;
a ceramic composition having a matrix comprising at least 50 volume percent of one or more of the carbides, nitrides and carbonitrides of hafnium, molybdenum, zirconium, tantalum, niobium, vanadium, tungsten, titanium, and solid solutions thereof, the matrix further includes sintering aid residue present from the use of one or more sintering aids as a starting component in an amount between greater than 0 and less than .5 weight percent of the starting components wherein the sintering aid comprises one or more of yttria, magnesia and zirconia, wherein the matrix comprises between 60 and 99.8 volume percent of the ceramic composition;
ceramic whiskers uniformly dispersed throughout the matrix wherein the ceramic whiskers comprise between 0.2 and 40 volume percent of the ceramic composition; and . further including a coating on the rake face and the flank face.
a rake face; and a flank face, a cutting edge at the juncture of the rake face and the flank face;
a ceramic composition having a matrix comprising at least 50 volume percent of one or more of the carbides, nitrides and carbonitrides of hafnium, molybdenum, zirconium, tantalum, niobium, vanadium, tungsten, titanium, and solid solutions thereof, the matrix further includes sintering aid residue present from the use of one or more sintering aids as a starting component in an amount between greater than 0 and less than .5 weight percent of the starting components wherein the sintering aid comprises one or more of yttria, magnesia and zirconia, wherein the matrix comprises between 60 and 99.8 volume percent of the ceramic composition;
ceramic whiskers uniformly dispersed throughout the matrix wherein the ceramic whiskers comprise between 0.2 and 40 volume percent of the ceramic composition; and . further including a coating on the rake face and the flank face.
2. The ceramic cutting tool of claim 1 wherein the coating comprises a layer selected from the group consisting of alumina, TiC, TiN, TiCN and TiA1N.
3. The ceramic cutting tool of claim 2 wherein the layer is applied by chemical vapor deposition.
4. The ceramic cutting tool of claim 2 wherein the layer is applied by physical vapor deposition.
5. The ceramic cutting tool of claim 1 wherein the ceramic whiskers comprise silicon carbide whiskers, and the silicon carbide whiskers comprise between about 2 volume percent to about 35 volume percent of the composition.
6. The ceramic cutting tool of claim 1 wherein the one or more sintering aids comprise an amount between greater than 0 and less than or equal to .3 weight percent of the starting components.
7. The ceramic cutting tool of claim 1 wherein the matrix comprises greater than 50 volume percent of titanium molybdenum carbide, and the balance of the matrix comprising at least 40 volume percent alumina.
8. The ceramic cutting tool of claim 7 wherein the ceramic whiskers comprise silicon carbide whiskers, and the silicon carbide whiskers comprise about 2 volume percent to about 35 volume percent of the cutting tool.
9. The ceramic cutting tool of claim 1 wherein the cutting tool has a hardness of greater than 94.7 Rockwell A.
10. A composition produced by the consolidation of a blend of starting components, the composition comprising:
a matrix comprising one or more of the carbides, nitrides and carbonitrides of hafnium, molybdenum, tungsten, zirconium, tantalum, niobium, vanadium, titanium, and solid solutions thereof, the matrix further includes sintering aid residue present from the use of one or more sintering aids as a starting component in an amount between greater than 0 and less than .5 weight percent of the starting components wherein the sintering aid comprises one or more of yttria, magnesia and zirconia, the matrix comprising between 60 and 99.8 volume percent of the composition;
ceramic whiskers uniformly dispersed throughout the matrix, the ceramic whiskers comprising between 0.2 and 40 volume percent of the composition;
and the composition having a hardness of greater than 94.7 Rockwell A.
a matrix comprising one or more of the carbides, nitrides and carbonitrides of hafnium, molybdenum, tungsten, zirconium, tantalum, niobium, vanadium, titanium, and solid solutions thereof, the matrix further includes sintering aid residue present from the use of one or more sintering aids as a starting component in an amount between greater than 0 and less than .5 weight percent of the starting components wherein the sintering aid comprises one or more of yttria, magnesia and zirconia, the matrix comprising between 60 and 99.8 volume percent of the composition;
ceramic whiskers uniformly dispersed throughout the matrix, the ceramic whiskers comprising between 0.2 and 40 volume percent of the composition;
and the composition having a hardness of greater than 94.7 Rockwell A.
11. The composition of claim 10 wherein the matrix comprises greater than 50 volume percent titanium carbonitride, and the balance of the matrix comprising at least 40 volume percent alumina; and wherein the titanium carbonitride has the formula Ti(CxNy) wherein y is less than 0.90 and greater than or equal to 0.55, and x + y = 1.
12. The composition of claim 10 wherein the ceramic whiskers comprise silicon carbide whiskers, and the silicon carbide whiskers comprise between about 10 volume percent to about 30 volume percent of the composition.
13. The composition of claim 10 wherein the one or more sintering aids comprise an amount between greater than 0 and less than or equal to .3 weight percent of the starting components.
14. A composition produced by the consolidation of a blend of starting components, the composition comprising:
a matrix comprising one or more of the carbides, nitrides and carbonitrides of hafnium, molybdenum, tungsten, zirconium, tantalum, niobium, vanadium, titanium, and solid solutions thereof, the matrix further includes sintering aid residue present from the use of one or more sintering aids as a starting component in an amount between greater than 0 and less than .5 weight percent of the starting components wherein the sintering aid comprises one or more of yttria, magnesia and zirconia, the matrix comprising between 60 and 99.8 volume percent of the composition;
ceramic whiskers uniformly dispersed throughout the matrix, the ceramic whiskers comprising between 0.2 and 40 volume percent of the composition;
wherein the matrix comprises greater than 50 volume percent titanium carbonitride, and the balance of the matrix comprising at least 40 volume percent alumina; and wherein the titanium carbonitride has the formula Ti(CxNy) wherein y is less than 0.75 and greater than or equal to 0.6, and x + y = 1.
a matrix comprising one or more of the carbides, nitrides and carbonitrides of hafnium, molybdenum, tungsten, zirconium, tantalum, niobium, vanadium, titanium, and solid solutions thereof, the matrix further includes sintering aid residue present from the use of one or more sintering aids as a starting component in an amount between greater than 0 and less than .5 weight percent of the starting components wherein the sintering aid comprises one or more of yttria, magnesia and zirconia, the matrix comprising between 60 and 99.8 volume percent of the composition;
ceramic whiskers uniformly dispersed throughout the matrix, the ceramic whiskers comprising between 0.2 and 40 volume percent of the composition;
wherein the matrix comprises greater than 50 volume percent titanium carbonitride, and the balance of the matrix comprising at least 40 volume percent alumina; and wherein the titanium carbonitride has the formula Ti(CxNy) wherein y is less than 0.75 and greater than or equal to 0.6, and x + y = 1.
15. A composition produced by the consolidation of a blend of starting components, the composition comprising:
a matrix consisting essentially of titanium carbonitride in an amount of about 50 volume percent or more of the matrix, alumina in an amount that is greater than 40 volume percent of the matrix, and sintering aid residue present from the use of one or more sintering aids as a starting component in an amount between greater than 0 and less than .5 weight percent of the starting components wherein the sintering aid comprises one or more of yttria, magnesia and zirconia;
the matrix comprising between 60 and 99.8 volume percent of the composition;
the composition further comprising ceramic whiskers uniformly dispersed throughout the matrix, the ceramic whiskers comprising between 0.2 and 40 volume percent of the composition; and the titanium carbonitride has the formula Ti (CxNy) wherein y is less than 0.9 and greater than or equal to 0.5, and x + y = 1.
a matrix consisting essentially of titanium carbonitride in an amount of about 50 volume percent or more of the matrix, alumina in an amount that is greater than 40 volume percent of the matrix, and sintering aid residue present from the use of one or more sintering aids as a starting component in an amount between greater than 0 and less than .5 weight percent of the starting components wherein the sintering aid comprises one or more of yttria, magnesia and zirconia;
the matrix comprising between 60 and 99.8 volume percent of the composition;
the composition further comprising ceramic whiskers uniformly dispersed throughout the matrix, the ceramic whiskers comprising between 0.2 and 40 volume percent of the composition; and the titanium carbonitride has the formula Ti (CxNy) wherein y is less than 0.9 and greater than or equal to 0.5, and x + y = 1.
16. The composition of claim 15 wherein the titanium carbonitride has the formula Ti(CxXNy) wherein y is equal to about 0.5, and x + y = 1.
17. The composition of claim 15 wherein the ceramic whiskers are selected from one or more of the following: alumina, silicon carbide, boron carbide, silicon nitride,, and the carbides, nitrides, borides, and carbonitrides of titanium, zirconium and hafnium.
18. The composition of claim 15 wherein the ceramic whiskers are selected from one or more of the following: titanium carbide, titanium boride, silicon carbide, and boron carbide.
19. The composition of claim 15 wherein the ceramic whiskers comprise silicon carbide, and the silicon carbide whiskers comprise between 2 volume percent and 35 volume percent of the composition.
20. The composition of claim 15 wherein the composition further comprising ceramic particulates selected from one or more of the group consisting of silicon carbide, titanium boride, zirconium boride, hafnium boride, alumina, zirconium oxide and hafnium oxide.
21. The composition of claim 15 wherein the ceramic whiskers comprise silicon carbide, and the silicon carbide whiskers have an average length of 10 to 80 micrometers, and an average diameter of 0.6 micrometers.
22. The composition of claim 21 wherein the crystalline structure of the silicon carbide is alpha silicon carbide.
23. The composition of claim 15 further defining a face, and a coating on the face.
24. The composition of claim 23 wherein the coating comprises at least one layer selected from one or more of the group consisting of alumina, TiC, TiN, TiCN, and TiA1N.
25. The composition of claim 24 wherein the one layer is applied by chemical vapor deposition.
26. The composition of claim 24 wherein the one layer is applied by physical vapor deposition.
27. The composition of claim 24 wherein the coating further comprises a second layer selected from one or more of the group consisting of alumina, TiC, TiN, TiCN, and TiA1N; and the one layer applied by chemical vapor deposition, and the second layer applied by physical vapor deposition.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US55775195A | 1995-11-13 | 1995-11-13 | |
| US08/557,751 | 1995-11-13 | ||
| PCT/US1996/015192 WO1997018177A1 (en) | 1995-11-13 | 1996-09-20 | Whisker reinforced ceramic cutting tool and composition thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2236818A1 true CA2236818A1 (en) | 1997-05-22 |
Family
ID=29405943
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2236818 Abandoned CA2236818A1 (en) | 1995-11-13 | 1996-09-20 | Whisker reinforced ceramic cutting tool and composition thereof |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2236818A1 (en) |
-
1996
- 1996-09-20 CA CA 2236818 patent/CA2236818A1/en not_active Abandoned
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