JP2015143171A - Diamond having controlled conductivity/electric resistance and preparation thereof - Google Patents
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- 239000010432 diamond Substances 0.000 title claims abstract description 106
- 229910003460 diamond Inorganic materials 0.000 title claims abstract description 104
- 238000002360 preparation method Methods 0.000 title abstract 2
- 239000002245 particle Substances 0.000 claims abstract description 47
- 239000000843 powder Substances 0.000 claims abstract description 34
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 21
- 238000010438 heat treatment Methods 0.000 claims abstract description 20
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 19
- 238000000034 method Methods 0.000 claims abstract description 11
- 239000007800 oxidant agent Substances 0.000 claims abstract description 9
- 239000001301 oxygen Substances 0.000 claims abstract description 8
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 8
- 238000010301 surface-oxidation reaction Methods 0.000 claims abstract description 8
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 7
- 125000000524 functional group Chemical group 0.000 claims abstract description 5
- 230000001590 oxidative effect Effects 0.000 claims abstract description 5
- 238000009826 distribution Methods 0.000 claims abstract description 4
- 238000004519 manufacturing process Methods 0.000 claims description 11
- 239000012298 atmosphere Substances 0.000 claims description 9
- VLTRZXGMWDSKGL-UHFFFAOYSA-N perchloric acid Chemical compound OCl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-N 0.000 claims description 6
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid Substances OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 6
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 5
- 229910017604 nitric acid Inorganic materials 0.000 claims description 5
- 239000000463 material Substances 0.000 claims description 4
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Chemical compound [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 claims description 4
- KRVSOGSZCMJSLX-UHFFFAOYSA-L chromic acid Substances O[Cr](O)(=O)=O KRVSOGSZCMJSLX-UHFFFAOYSA-L 0.000 claims description 2
- AWJWCTOOIBYHON-UHFFFAOYSA-N furo[3,4-b]pyrazine-5,7-dione Chemical compound C1=CN=C2C(=O)OC(=O)C2=N1 AWJWCTOOIBYHON-UHFFFAOYSA-N 0.000 claims description 2
- 239000004323 potassium nitrate Substances 0.000 claims description 2
- 235000010333 potassium nitrate Nutrition 0.000 claims description 2
- 239000012286 potassium permanganate Substances 0.000 claims description 2
- 239000000470 constituent Substances 0.000 claims 1
- 230000014759 maintenance of location Effects 0.000 claims 1
- 239000006061 abrasive grain Substances 0.000 abstract description 34
- 238000006243 chemical reaction Methods 0.000 abstract description 11
- 229910052751 metal Inorganic materials 0.000 abstract description 7
- 239000002184 metal Substances 0.000 abstract description 7
- 238000007747 plating Methods 0.000 abstract description 5
- 238000004220 aggregation Methods 0.000 abstract 1
- 230000002776 aggregation Effects 0.000 abstract 1
- 230000002401 inhibitory effect Effects 0.000 abstract 1
- 230000001105 regulatory effect Effects 0.000 abstract 1
- 238000000576 coating method Methods 0.000 description 13
- 239000011248 coating agent Substances 0.000 description 12
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 9
- 239000010410 layer Substances 0.000 description 8
- 230000015572 biosynthetic process Effects 0.000 description 5
- 238000004070 electrodeposition Methods 0.000 description 5
- 238000005087 graphitization Methods 0.000 description 5
- MTPVUVINMAGMJL-UHFFFAOYSA-N trimethyl(1,1,2,2,2-pentafluoroethyl)silane Chemical compound C[Si](C)(C)C(F)(F)C(F)(F)F MTPVUVINMAGMJL-UHFFFAOYSA-N 0.000 description 5
- 238000005520 cutting process Methods 0.000 description 4
- 229910052759 nickel Inorganic materials 0.000 description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
- 239000003082 abrasive agent Substances 0.000 description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 3
- 239000010949 copper Substances 0.000 description 3
- 239000011259 mixed solution Substances 0.000 description 3
- 239000007858 starting material Substances 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 229910002091 carbon monoxide Inorganic materials 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 239000012299 nitrogen atmosphere Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 238000005498 polishing Methods 0.000 description 2
- 239000010936 titanium Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 1
- 229910002601 GaN Inorganic materials 0.000 description 1
- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 238000003763 carbonization Methods 0.000 description 1
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 description 1
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 150000002927 oxygen compounds Chemical class 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 229910052594 sapphire Inorganic materials 0.000 description 1
- 239000010980 sapphire Substances 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
Abstract
Description
本発明は砥粒としてのダイヤモンド粒子において、粒子表面の非ダイヤモンド炭素化、特にグラファイト化によって一定の導電性が付与されたダイヤモンド及びその製造方法に関する。 The present invention relates to diamond in which diamond particles as abrasive grains are imparted with a certain conductivity by non-diamond carbonization of the particle surface, particularly graphitization, and a method for producing the same.
数あるダイヤモンドの優れた特性の一つとして高い電気抵抗値が挙げられる。しかしこれが工具製作において障害になる場合もある。例えば電気メッキの手法により、析出したニッケルによって芯線上にダイヤモンド砥粒が固定されたワイヤソーの製造においては、芯線上にダイヤモンド砥粒が適当な間隔で一様に分布し、かつ切断刃先では砥粒が露出していることが要求されている。この要求に対応する解決方法の一つとして、砥粒表面に適当な導電性を付与することが求められている。 One of the excellent properties of many diamonds is high electrical resistance. However, this can be an obstacle in tool production. For example, in the manufacture of a wire saw in which diamond abrasive grains are fixed on the core wire by the deposited nickel by an electroplating technique, the diamond abrasive grains are uniformly distributed on the core wire at appropriate intervals, and the cutting blade tip has abrasive grains. Is required to be exposed. As one of the solutions corresponding to this requirement, it is required to impart appropriate conductivity to the abrasive grain surface.
即ち市販の非被覆ダイヤモンド砥粒を用いた場合には、砥粒表面の電気抵抗値が高過ぎることから (1010Ω・m以上) 芯線上への砥粒の付着が悪く、所要の砥粒密度が得られない。一方、表面にニッケルや銅の金属メッキを施した砥粒では電気抵抗値は極めて低い(粉体(乃至微粒子集合体)を圧縮して一つのバルク試料とみなした比抵抗換算で10-3Ω・m未満)ことから、芯線上への砥粒の付着密度が高くなりすぎる一方、析出したニッケルが砥粒を覆ってしまうので、追加工程として切断刃先を露出させるためのツルーイングを行うことが必要となっている。 That is, when using a commercially available uncoated diamond abrasive grain, the electrical resistance value of the abrasive grain surface is too high (10 10 Ω ・ m or more). The density cannot be obtained. On the other hand, the electrical resistance value is extremely low with abrasive particles plated with nickel or copper on the surface (powder (or fine particle aggregate) is compressed to 10 -3 Ω in terms of specific resistance regarded as one bulk sample) (Below m), the adhesion density of the abrasive grains on the core wire becomes too high, while the deposited nickel covers the abrasive grains, so it is necessary to perform truing to expose the cutting edge as an additional step It has become.
一方、近年の電子工業の進展により、ワイヤソーで切断される材料も、シリコン、窒化ガリウム、サファイア等と多様化かつ硬質への適用も増え、砥粒の芯線への保持強度に対する要求も厳しくなってきている。 On the other hand, with the progress of the electronics industry in recent years, materials that are cut with a wire saw are diversified and applied to silicon, gallium nitride, sapphire, etc., and the demand for holding strength of the abrasive grains on the core wire has become stricter. ing.
金属メッキに比べて電気抵抗値の高い表面状態を得る手段として、ダイヤモンド粒子の表面に炭化チタン被覆を施した砥粒をワイヤソーに適用することが公知である。 As a means for obtaining a surface state having a higher electric resistance value than metal plating, it is known to apply abrasive grains having titanium carbide coating on the surface of diamond particles to a wire saw.
この砥粒の電気抵抗値は前出のバルク比抵抗値でおよそ10-3〜10-1Ω・ｍの領域であって広く用いられてはいるが、電着工程の管理を容易にしてより均一な砥粒の付着を達成するために、これより数桁高い電気抵抗値を有する砥粒が求められている。 The electric resistance value of this abrasive grain is approximately 10 -3 to 10 -1 Ω · m in the above-mentioned bulk specific resistance value, and it is widely used. In order to achieve uniform adhesion of abrasive grains, there is a need for abrasive grains having electrical resistance values that are several orders of magnitude higher than this.
しかしながら、電着工具用砥粒の製造のためのダイヤモンド粒子表面へのニッケル、その他の金属被覆工程はメッキ操作によって行われるが、通常その初期過程において島状に成長することから、比抵抗値を上げるために膜厚を薄くすると連続膜が得られなくなるので、膜厚の管理によって電気抵抗を制御することは困難である。 However, nickel and other metal coating processes on the surface of diamond particles for the production of abrasives for electrodeposition tools are carried out by plating operations. If the film thickness is decreased to increase the thickness, a continuous film cannot be obtained. Therefore, it is difficult to control the electrical resistance by managing the film thickness.
一方、炭化チタン被覆の場合はダイヤ表面の炭素を利用して被覆するため金属メッキよりは電気抵抗制御に有利であるが、この場合も、比抵抗値を増すために炭化チタン被覆厚さを減少させようとすると連続した被覆膜が得られにくくなるため、安定した電気抵抗値を得るのが困難となる。 On the other hand, in the case of titanium carbide coating, the carbon on the diamond surface is used for coating, which is more advantageous for controlling electrical resistance than metal plating. In this case, too, the titanium carbide coating thickness is reduced to increase the specific resistance value. If this is attempted, it becomes difficult to obtain a continuous coating film, and it becomes difficult to obtain a stable electrical resistance value.
例えばＴiコート率をダイヤモンド重量に対して10〜0.3質量％と変化させた場合、バルク比抵抗値は8・10-4〜5・10-2Ω・mが限度であり、これ以上Ｔiコート率を下げると、安定した電気抵抗は得られない。 For example, when the Ti coating rate is changed from 10 to 0.3% by mass with respect to the diamond weight, the bulk resistivity value is limited to 8 · 10 −4 to 5 · 10 −2 Ω · m. If the value is lowered, stable electric resistance cannot be obtained.
ダイヤモンドは空気中或いは真空中での高温への加熱により非ダイヤモンド炭素(グラファイト)化することは公知であり、個々の粒子に就いて研磨性能を最適化するためにダイヤモンド粒子を加熱処理すること、特に研磨材として部分的に非ダイヤモンド化したダイヤモンドを研磨剤として使用することは5μm以下の微細な粉体について実用化され、シャープな切れ味と微細な研磨仕上げ面とが同時に得られる研磨材となっている。 Diamond is known to be non-diamond carbon (graphite) by heating to high temperature in air or in vacuum, heat treating diamond particles to optimize polishing performance for individual particles, In particular, the use of partially non-diamond diamond as an abrasive material has been put to practical use for fine powders of 5 μm or less, resulting in an abrasive material that can simultaneously achieve sharp sharpness and a fine polished surface. ing.
しかしこの処理は、専ら精密仕上げのために遊離砥粒として使用される5μm以下の微細な粉体の表面の研磨性能を最適化するものであり、この際、微細な研磨仕上げ面を得るために、砥粒が被削材に接する際の衝撃吸収、切れ刃の突出し高さの制御を目的として、砥粒のダイヤモンド表面に、0.5質量％以上の自身のダイヤモンドからの転化によって生じた非ダイヤモンド炭素を形成させることが特徴となっている。この際の非ダイヤモンド炭素量は、ダイヤモンドと非ダイヤモンド炭素との酸化速度の差を利用し、酸化剤を用いて砥粒表面の非ダイヤモンド炭素を除去する操作における質量変化に基づいて算出される。 However, this treatment optimizes the polishing performance of the surface of fine powder of 5 μm or less used exclusively as loose abrasive grains for precision finishing. In this case, in order to obtain a fine polished surface Non-diamond carbon produced by conversion of 0.5% by mass or more of its own diamond onto the diamond surface of the abrasive grains for the purpose of absorbing impact when the abrasive grains contact the work material and controlling the protruding height of the cutting edge It is characterized by forming. The amount of non-diamond carbon at this time is calculated on the basis of a change in mass in an operation of removing non-diamond carbon on the surface of an abrasive grain using an oxidizing agent by utilizing a difference in oxidation rate between diamond and non-diamond carbon.
従って本発明の主な目的の一つは、ダイヤモンド電着工具の製作において、ダイヤモンド砥粒の本来の特性を損なうことなく、メッキ操作において析出金属の過度の成長を抑制し、また固着粒子の凝集防止、後処理工程の低減を可能としたダイヤモンド粒子及びその製法を提供することである。 Therefore, one of the main objects of the present invention is to suppress excessive growth of the deposited metal in the plating operation without damaging the original characteristics of the diamond abrasive grains in the production of the diamond electrodeposition tool, and to agglomerate the fixed particles. The object is to provide diamond particles that can be prevented and reduced in post-treatment steps, and a method for producing the same.
本発明者らはダイヤモンド粒子表面の加熱時のいくつかの物性の変化に着目し、前処理及びダイヤモンドへ付加する熱量の制御によってダイヤモンド粒子の表面全体にごく薄い非ダイヤモンド炭素、特にグラファイト化層を形成し、形成条件を適切に管理することによって、従来の金属や炭化チタン被覆技術では到達不可能な領域において任意に制御された所望の導電率(電気抵抗値)を付与できることを知見し、本発明に至った。 The present inventors pay attention to some changes in physical properties during heating of the diamond particle surface. By controlling the amount of heat applied to the diamond and pretreatment, a very thin non-diamond carbon, particularly a graphitized layer, is formed on the entire surface of the diamond particle. By forming and appropriately managing the formation conditions, we have found that it is possible to give the desired conductivity (electric resistance value) that is arbitrarily controlled in a region that cannot be achieved by conventional metal and titanium carbide coating technologies. Invented.
本発明の要旨とするところは、導電性ダイヤモンドは、一定の粒度分布を有する整粒されたダイヤモンド粉体において、該粉体を構成する粒子が、ダイヤモンド粒子表面に存在する非ダイヤモンド相に基づく制御された電気抵抗を有することである。 The gist of the present invention is that the conductive diamond is controlled based on a non-diamond phase in which the particles constituting the powder exist in the diamond particle surface having a constant particle size distribution. It has an electrical resistance.
このような導電性ダイヤモンドは、ダイヤモンド粉体を第一の酸化剤中において加熱することにより、粉体構成粒子の表面に酸素含有官能基を形成させる表面酸化工程と、 表面が酸化されたダイヤモンド粒子を1000℃以上1500℃以下に加熱することにより、該ダイヤモンド粒子の表層部を非ダイヤモンド炭素に変換し、この相変換によって最低10-3Ω・mのオーダー、最高107Ω・mのオーダーの導電性を付与する工程とから成る方法により、効果的に調製できる。 Such a conductive diamond includes a surface oxidation step in which an oxygen-containing functional group is formed on the surface of the powder constituting particles by heating the diamond powder in a first oxidizing agent, and the diamond particles whose surface is oxidized. Is heated to 1000 ° C or higher and 1500 ° C or lower to convert the surface layer of the diamond particles into non-diamond carbon. By this phase conversion, the minimum order is 10 -3 Ω · m and the maximum order is 10 7 Ω · m. It can be effectively prepared by a method comprising a step of imparting electrical conductivity.
加熱雰囲気、加熱温度、保持時間などの条件を制御によりダイヤモンド粒子に適切に制御された導電性を付与する本発明によれば、必要に応じた電気抵抗値を有するダイヤモンド砥粒を作製可能なため、例えばワイヤソー製造工程において、工具に応じた最適な電気抵抗値を有する砥粒を選択でき、所望のコート状態の実現が可能となった。 According to the present invention that imparts appropriately controlled conductivity to diamond particles by controlling conditions such as heating atmosphere, heating temperature, and holding time, diamond abrasive grains having an electrical resistance value as required can be produced. For example, in a wire saw manufacturing process, it is possible to select abrasive grains having an optimum electric resistance value according to a tool, and a desired coat state can be realized.
本発明において用いる電気抵抗値は、アルミナ製の筒状試料ホルダーに充填した試料のダイヤモンド粉体を、銅製の電極で挟んで加圧装置へ取り付け、 電極間に10ＭＰa前後の圧力を付加する測定法に拠って得られる。この装置によって得られた比抵抗値の例を挙げると、銅コートダイヤモンド粉体について2・10-4Ω・ｍ未満、炭化チタンコートダイヤモンド粉体については1・10-３〜1・10-2Ω.ｍの近傍である。 The electrical resistance value used in the present invention is a measurement method in which a diamond powder sample filled in an alumina cylindrical sample holder is sandwiched between copper electrodes and attached to a pressure device, and a pressure of about 10 MPa is applied between the electrodes. Obtained based on Examples of specific resistance values obtained with this apparatus are less than 2 · 10 −4 Ω · m for copper-coated diamond powder, and 1 · 10 −3 to 1 · 10 −2 for titanium carbide-coated diamond powder. It is in the vicinity of Ω.m.
本発明におけるダイヤモンドへの導電性の付与は、0.5質量％未満のごく薄い非ダイヤモンド炭素膜の形成によっても達成され、過度の形成を必要としない。却って、過度の層形成は高負荷研削における切れ味の低下をもたらし、また電着工具においては、基材金属との境界部に好ましくない低強度の中間層が存在することとなるので、好ましくない。 The imparting of conductivity to diamond in the present invention can be achieved even by forming a very thin non-diamond carbon film of less than 0.5% by mass and does not require excessive formation. On the other hand, excessive layer formation causes a reduction in sharpness in high-load grinding, and in an electrodeposition tool, an undesirably low-strength intermediate layer exists at the boundary with the base metal, which is not preferable.
本発明においてはダイヤモンド粒子全表面に導電性を付与するのが好ましく、そのための前処理工程として、表面酸化反応が必須となる。酸化処理によって砥粒表面に酸素を含む官能基の存在が認められ、この酸素がダイヤモンド表面の炭素原子と結合し、ＣＯまたはＣＯ2ガスとして脱離することで生じたダングリングボンドが、表面グラファイト化即ちsp2結合形成の引き金になっている。高温において表面に形成されたsp2結合は次第に砥粒内部へ伝播し、ダイヤモンド砥粒表面が非ダイヤモンド炭素層で覆われていくことがＴＥＭ観察で認められている。 In the present invention, it is preferable to impart conductivity to the entire surface of the diamond particles, and a surface oxidation reaction is essential as a pretreatment step for that purpose. The presence of functional groups containing oxygen is recognized on the surface of the abrasive grains by the oxidation treatment, and the dangling bonds generated by this oxygen bonding to carbon atoms on the diamond surface and desorbing as CO or CO 2 gas are caused by surface graphite. It triggers the formation of sp 2 bonds. It has been observed by TEM observation that sp 2 bonds formed on the surface at a high temperature gradually propagate into the abrasive grains and the diamond abrasive grain surface is covered with a non-diamond carbon layer.
表面酸化反応は酸素含有雰囲気中における400℃以上の乾式加熱でも達成可能であるが、より均一な酸化表面を得るために湿式反応によるのが好ましい。湿式反応の酸化剤の好適例として、過塩素酸或いは濃硫酸と濃硝酸との組み合わせを挙げることができる。 The surface oxidation reaction can be achieved by dry heating at 400 ° C. or higher in an oxygen-containing atmosphere, but it is preferable to use a wet reaction in order to obtain a more uniform oxidized surface. Preferable examples of the oxidizing agent for the wet reaction include perchloric acid or a combination of concentrated sulfuric acid and concentrated nitric acid.
さらに硝酸カリ、過マンガン酸カリ、クロム酸などの酸化剤を添加するとより有効である。湿式反応の加熱温度としては、過塩素酸ベースの場合は150℃以上、濃硫酸ベースの場合は250℃以上が実用上好ましい。 Furthermore, it is more effective to add an oxidizing agent such as potassium nitrate, potassium permanganate or chromic acid. The heating temperature for the wet reaction is preferably 150 ° C. or higher for the perchloric acid base and 250 ° C. or higher for the concentrated sulfuric acid base.
ダイヤモンド粒子表面のグラファイト化は処理温度800℃付近から認められ、1000℃以上で顕著になる。表面グラファイト化の際の加熱処理雰囲気としては非酸化性、特に、真空中、またはアルゴン、窒素、ヘリウムなどの中性のガスが好ましい。また反応雰囲気中に微量の酸素、酸素化合物(水蒸気、炭酸ガス)が存在させるとグラファイト化が促進されるので、処理温度を低くできる利点がある。 The graphitization of the diamond particle surface is recognized from a treatment temperature of around 800 ° C, and becomes noticeable at 1000 ° C or higher. The heat treatment atmosphere for the surface graphitization is preferably non-oxidizing, particularly a vacuum or a neutral gas such as argon, nitrogen or helium. In addition, if a trace amount of oxygen or oxygen compound (water vapor, carbon dioxide) is present in the reaction atmosphere, graphitization is promoted, which has an advantage that the processing temperature can be lowered.
一方水素を代表とする還元性雰囲気は、ダングリングボンドが水素で終端されることにより、砥粒表面におけるグラファイト化反応が抑制されるので好ましくない。 On the other hand, a reducing atmosphere typified by hydrogen is not preferable because dangling bonds are terminated with hydrogen, so that the graphitization reaction on the abrasive grain surface is suppressed.
表面に制御された非ダイヤモンド炭素層を有するダイヤモンド粒子は、電鋳工具や電着工具の製造において、砥粒表面への析出金属の付き回り量のコントロールが可能となり、これによって、結合材金属からの砥粒突き出し高さを任意に変えることも可能になる。 The diamond particles having a non-diamond carbon layer controlled on the surface can control the amount of deposited metal on the abrasive grain surface in the production of electroformed tools and electrodeposition tools. It is also possible to arbitrarily change the protruding height of the abrasive grains.
砥粒表面の電気伝導性は、主として砥粒表面への非ダイヤモンド炭素の被覆率に依存し、また被覆厚さにも依存すると考えられる。被覆率を高める手段としては、前駆体とも言うべき酸素含有官能基の形成密度を上げる必要から前記した湿式高温処理が用いられる。 It is considered that the electrical conductivity of the abrasive grain surface mainly depends on the coverage of non-diamond carbon on the abrasive grain surface and also on the coating thickness. As a means for increasing the coverage, the wet high temperature treatment described above is used because it is necessary to increase the density of formation of oxygen-containing functional groups, which can also be referred to as a precursor.
被覆厚さの制御項目としては加熱雰囲気、加熱温度、保持時間が挙げられる。これらの組合せ制御によって 10-3Ω・mから 107Ω・mのオーダーに至る広い領域に亘って比抵抗値の制御が可能である。即ち被覆炭素層を薄く抑えることによって従来の被覆技術では達成困難であった107Ω・mのオーダーの比抵抗値を有する砥粒とすることが可能であり、また充分に厚い被覆を形成することによって、厚いチタンコートに匹敵する10-3Ω・mのオーダーの比抵抗値を有する砥粒を得ることも可能である。 Control items for the coating thickness include heating atmosphere, heating temperature, and holding time. By these combination controls, it is possible to control the specific resistance value over a wide region ranging from 10 −3 Ω · m to 10 7 Ω · m. In other words, by keeping the coating carbon layer thin, it is possible to obtain abrasive grains having a specific resistance value on the order of 10 7 Ω · m, which was difficult to achieve with conventional coating techniques, and forming a sufficiently thick coating. Thus, it is possible to obtain abrasive grains having a specific resistance value on the order of 10 −3 Ω · m, which is comparable to a thick titanium coat.
因みに直径10μmのダイヤモンド粒子表面に0.5質量％の非ダイヤモンド炭素被覆層を形成(転化)させた場合の層の厚さは約3nm、即ち10原子層程度と見積もられ、電気伝導性の発現が理解される。 Incidentally, when a 0.5 mass% non-diamond carbon coating layer is formed (converted) on the surface of a diamond particle having a diameter of 10 μm, the thickness of the layer is estimated to be about 3 nm, that is, about 10 atomic layers. Understood.
出発原料のＩＲＭ10-20 (Ｄ50 = 13.5μm)を、濃硫酸・濃硝酸混液中における300℃で１時間の加熱による表面酸化反応を行った。水洗・乾燥した粉末は、ＦＴＩＲによってカルボニル基、カルボキシル基、ヒドロキシル基に帰属する明瞭な吸収図形を確認した。 The starting material, IRM10-20 (D 50 = 13.5 μm), was subjected to a surface oxidation reaction by heating at 300 ° C. for 1 hour in a mixed solution of concentrated sulfuric acid and concentrated nitric acid. The powder washed and dried confirmed clear absorption patterns attributed to carbonyl group, carboxyl group and hydroxyl group by FTIR.
この粉末をアルミナ製こう(匣)鉢に入れ、窒素雰囲気中において1280℃に3時間保持する加熱を行い、灰色に変色した生成粉を得た。この粉末は10ＭＰaの加圧状態における電気抵抗値測定で8・102Ω・mの値を示した。 This powder was put in an alumina pot (heater) and heated in a nitrogen atmosphere at 1280 ° C. for 3 hours to obtain a product powder which turned gray. This powder showed a value of 8 · 10 2 Ω · m when measured for electric resistance in a pressurized state of 10 MPa.
得られた粉末を用いて電着ワイヤソーを試作したところ、砥粒先端付近（ワイヤソー外周部）のダイヤモンド粒子表面が一部露出した状態でワイヤー母材表面に付着している様子を確認することができた。このことは、ワイヤソーの電着工程後に余計な砥粒やＮiを除くための工程を必要とせず、すぐに切断能力を発揮することができることを意味している。 When an electrodeposited wire saw was made using the obtained powder, it was confirmed that the diamond particle surface near the tip of the abrasive grain (outer part of the wire saw) was partly exposed and adhered to the wire base material surface. did it. This means that the cutting ability can be exhibited immediately without the need for a process for removing excess abrasive grains and Ni after the electrodeposition process of the wire saw.
出発原料としてＩＲＭ8-16(Ｄ50 = 9.2μm)を用い、実施例1と同じ操作によって表面酸化粉末を得た。 Using IRM8-16 (D 50 = 9.2 μm) as a starting material, surface oxidized powder was obtained by the same operation as in Example 1.
この粉末をアルミナ製こう鉢に入れ、窒素雰囲気中において1075℃に３時間保持する加熱を行い、淡灰色に変色した生成粉を得た。この粉末は10ＭＰaの加圧状態における電気抵抗値測定で2・107Ω・mの値を示した。 This powder was put into an alumina pot and heated to 1075 ° C. for 3 hours in a nitrogen atmosphere to obtain a product powder that turned pale gray. This powder showed a value of 2 · 10 7 Ω · m when measured in electrical resistance under a pressure of 10 MPa.
得られた加熱処理粉末の一部を秤取し、約300℃の濃硫酸・濃硝酸混液中における加熱反応によって、粉末表面に形成された非ダイヤモンド炭素相を酸化除去した。加熱反応前後の質量変化から、本加熱処理粉末は0.15％の非ダイヤモンド炭素相を有していたと見積もられた。 A part of the obtained heat-treated powder was weighed, and the non-diamond carbon phase formed on the powder surface was oxidized and removed by a heating reaction in a mixed solution of concentrated sulfuric acid and concentrated nitric acid at about 300 ° C. From the mass change before and after the heating reaction, it was estimated that this heat-treated powder had a non-diamond carbon phase of 0.15%.
粒度の異なるいくつかのダイヤモンドを出発原料として用い、濃硫酸・濃硝酸混液中における300℃で１時間の加熱による表面酸化反応後、水洗・乾燥した。さらに処理雰囲気、加熱温度、及び保持時間を変化させてダイヤモンドの表面導電化処理を行い、得られたダイヤモンド粉末の比抵抗値を測定した。
加熱処理条件及び得られたダイヤモンド粉末の比抵抗値、また参考値として、ダイヤモンド粒子表面に形成された非ダイヤモンド炭素相の割合(質量％)を併せて示す。
Several diamonds with different particle sizes were used as starting materials, and after surface oxidation reaction by heating at 300 ° C. for 1 hour in a mixed solution of concentrated sulfuric acid and concentrated nitric acid, they were washed with water and dried. Furthermore, the surface atmosphere of the diamond was changed while changing the treatment atmosphere, heating temperature, and holding time, and the specific resistance value of the obtained diamond powder was measured.
The ratio (mass%) of the non-diamond carbon phase formed on the diamond particle surface is also shown as a heat treatment condition, the specific resistance value of the obtained diamond powder, and a reference value.
Claims (12)
表面が酸化されたダイヤモンド粒子を非酸化性雰囲気中で1000℃以上1500℃以下の加熱温度に制御された保持時間供することにより、該ダイヤモンド粒子の表層部を非ダイヤモンド炭素に変換し、この相変換により10ＭＰaの加圧下の測定による比抵抗において最低10-3Ω・mのオーダー、最高107Ω・mのオーダーの導電性を付与する工程
を含む、請求項１に記載の導電性ダイヤモンドの製造方法。 A surface oxidation step for forming oxygen-containing functional groups on the surface of the powder constituent particles by heating the diamond powder in the first oxidizing agent, and the diamond particles whose surface is oxidized in a non-oxidizing atmosphere ° C. by subjecting 1500 ° C. below the heating temperature to control retention time or more, to convert the surface portion of the diamond particles in the non-diamond carbon, a minimum of 10 -3 in the specific resistance by measuring the pressure of 10MPa by the phase change The method for producing a conductive diamond according to claim 1, comprising a step of imparting a conductivity of the order of Ω · m, up to 10 7 Ω · m.
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| JP2002060733A (en) * | 2000-08-17 | 2002-02-26 | Ishizuka Kenkyusho:Kk | Diamond-polishing material particle and method for producing the same |
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