JP2004026514A - Cubic boron nitride sintered compact and its manufacturing method - Google Patents
Cubic boron nitride sintered compact and its manufacturing method Download PDFInfo
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- 229910052582 BN Inorganic materials 0.000 title claims abstract description 53
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 title claims abstract description 53
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 18
- 238000001816 cooling Methods 0.000 claims abstract description 29
- 239000000758 substrate Substances 0.000 claims abstract description 12
- 238000005245 sintering Methods 0.000 claims abstract description 8
- 150000001875 compounds Chemical class 0.000 claims description 8
- 239000011230 binding agent Substances 0.000 claims description 7
- 238000005520 cutting process Methods 0.000 claims description 5
- 150000001247 metal acetylides Chemical class 0.000 claims description 4
- 150000004767 nitrides Chemical class 0.000 claims description 4
- 229910021472 group 8 element Inorganic materials 0.000 claims description 3
- 238000000034 method Methods 0.000 abstract description 2
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- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- 229910015325 MoFe Inorganic materials 0.000 description 2
- 108010038629 Molybdoferredoxin Proteins 0.000 description 2
- 229910052796 boron Inorganic materials 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 238000011161 development Methods 0.000 description 2
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- 239000002994 raw material Substances 0.000 description 2
- 229910015234 MoCo Inorganic materials 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
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- 229910052748 manganese Inorganic materials 0.000 description 1
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Abstract
Description
【０００１】
【発明の属する技術分野】
本発明は、高硬度で優れた耐摩耗性を有し、切削工具、軸受け、線引ダイス等の耐摩耗用素材として賞用される、立方晶窒化ホウ素焼結体の製造方法の改良に関する。
【０００２】
【従来の技術】
切削工具等の耐摩耗用素材としては、従来より炭化タングステン（ＷＣ）基の超硬材料が使用されてきた。しかしながら、需要者の要求がますます厳しくなっている現在、上記ＷＣ基超硬材料では需要者の要求を満たすことが困難となってきており、より優秀な耐摩耗用素材の開発が期待されている。
【０００３】
こうした要望に沿う耐摩耗用素材として、立方晶窒化ホウ素粉末に少量のＡｌと、Ｎｉ、Ｃｏ、Ｍｎ、Ｆｅ、Ｖからなる群から選択された合金元素の少なくとも一種を含む金属相を含有させた焼結体（特開昭４８−１７５０３号公報）、あるいはセラミックスを結合材として用いたｃＢＮ焼結体（特公昭５７−３６３１号公報）等が提案されている。これらの焼結体は、工具としての強度を確保する等の目的から、一般に超硬合金からなる基板と一体焼結されている。
【０００４】
上記のような一体焼結体は、所定の厚さに研削加工した後ワイヤ−放電加工等により所望の形状に切断され、工具として仕上げられる場合と、所定の厚さに研削加工した後ワイヤ−放電加工等により所望の形状に切断され、その後、一般には超硬合金製の台金にろう付けされ、工具として仕上げられる場合がある。何れの場合においても、一体焼結体を実用に供するには、高温高圧装置より取り出された状態から、研削加工により厚さを減少させる必要がある。
【０００５】
一方、これらの立方晶窒化ホウ素焼結体と超硬合金製基板の熱膨張係数は一致しないことが多く、そのため、一体焼結体には熱応力が残留している。このような熱応力が残留している一体焼結体の厚さを研削加工により減少させると、応力のバランスが崩れるため、しばしば、湾曲等の変形を生じる。湾曲等の変形は、その後の精密加工の障害となるため、研削加工により厚さが減少しても変形を生じ難い一体焼結体の開発が望まれていた。
【０００６】
【発明が解決しようとする課題】
平面研削加工により厚さを減少させても、変形量が小さい立方晶窒化ホウ素焼結体、超硬合金製基板一体焼結体を提供する。
【０００７】
【課題を解決するための手段】
本発明者らは鋭意研究を重ねた結果、高温高圧下で立方晶窒化ホウ素焼結体を製造する方法において、８００℃から６００℃までの冷却を平均２００℃／分以下の冷却速度とするにより、研削加工により厚さが減少しても変形を生じにくい一体焼結体が得られることを見出し、本発明を完成させるに至った。
【０００８】
本発明の製造方法により、研削加工により厚さが減少しても変形を生じにくい一体焼結体が得られる理由は、８００℃から６００℃までの冷却を平均２００℃／分以下の冷却速度とするにより、超硬合金に含有されるＣｏやＷＣ等が、再配列等により移動し、そのため、立方晶窒化ホウ素焼結体と超硬合金製基板の熱膨張係数差による残留熱応力が緩和されるためと推察される。
【０００９】
すなわち、本発明は、以下（１）〜（１１）に関する。
（１）高温高圧下で立方晶窒化ホウ素焼結体を製造する方法において、焼結後、８００℃から６００℃までの平均冷却速度が、２００℃／分以下であることを特徴とする立方晶窒化ホウ素焼結体の製造方法。
（２）８００℃から６００℃までの平均冷却速度が、３０℃／分以下である前項１に記載の立方晶窒化ホウ素焼結体の製造方法。
（３）８００℃から６００℃までの平均冷却速度が、１０〜２００℃／分である前項１に記載の立方晶窒化ホウ素焼結体の製造方法。
（４）８００℃から６００℃までの平均冷却速度が、１０℃〜３０℃／分以下である前項１に記載の立方晶窒化ホウ素焼結体の製造方法。
（５）前項１乃至４のいずれか１項に記載の製造方法で得られる立方晶窒化ホウ素焼結体。
（６）立方晶窒化ホウ素焼結体が、結合材を含む前項５に記載の立方晶窒化ホウ素焼結体。
（７）結合材が、ＩＶａ〜ＶＩａ族元素の窒化物、炭化物、炭窒化物、ホウ化物、ＩＶａ〜ＶＩａ族元素とＶＩＩＩ族元素とからなるホウ化物、及びＡｌの化合物からなる群より選ばれる少なくとも１種の化合物である前項６に記載の立方晶窒化ホウ素焼結体。
（８）立方晶窒化ホウ素焼結体が、超硬合金製基板との一体焼結体となっている前項５に記載の立方晶窒化ホウ素焼結体。
【００１０】
（９）前項５乃至８のいずれか１項に記載の立方晶窒化ホウ素焼結体を用いたことを特徴とする切削工具。
（１０）前項５乃至８のいずれか１項に記載の立方晶窒化ホウ素焼結体を用いたことを特徴とする軸受け。
（１１）前項５乃至８のいずれか１項に記載の立方晶窒化ホウ素焼結体を用いたことを特徴とする線引ダイス。
【００１１】
【発明の実施の形態】
本発明において、焼結後、８００℃から６００℃までの平均冷却速度が、２００℃／分以下であり、好ましくは、３０℃／分以下である。平均冷却速度が２００℃／分より速いと、立方晶窒化ホウ素焼結体と超硬合金製基板の熱膨張係数差による残留熱応力の緩和が不充分であり、研削加工による厚さの減少による変形量が大きく好ましくない。平均冷却速度の下限は、特に無いが、生産効率の観点から１０℃／分以上が好ましい。
【００１２】
本発明の立方晶窒化ホウ素焼結体は、結合材を含んでもよい。結合材としては、例えば、ＩＶａ，Ｖａ，ＶＩａ族元素の窒化物、炭化物、炭窒化物、ホウ化物、ＩＶａ，Ｖａ，ＶＩａ族元素とＶＩＩＩ族元素とからなるホウ化物、及びＡｌの化合物が挙げられる。
【００１３】
ＩＶａ，Ｖａ，ＶＩａ族元素の窒化物、炭化物、炭窒化物、ホウ化物、ＩＶａ，Ｖａ，ＶＩａ族元素とＶＩＩＩ族元素とからなるホウ化物、Ａｌの化合物としては、例えば、ＴｉＣ，ＴｉＢ２，Ｔｉ２Ｂ５，Ｔｉ３Ｂ４，ＴｉＢ，ＴｉＮ，Ｔｉ２Ｎ，ＴｉＣｘＮ１−ｘ（０＜ｘ＜１），ＺｒＣ，ＺｒＢ２，ＺｒＢ１２，ＺｒＮ，ＺｒＣｘＮ１−ｘ（０＜ｘ＜１），ＨｆＣ，ＨｆＢ２，ＨｆＢ，ＨｆＢ１２，Ｈｆ３Ｎ２，ＨｆＮ，Ｈｆ４Ｎ３，ＨｆＣｘＮ１−ｘ（０＜ｘ＜１），ＶＣ，Ｖ４Ｃ３，Ｖ８Ｃ７，ＶＢ２，Ｖ３Ｂ４，Ｖ３Ｂ１２，ＶＢ，Ｖ５Ｂ６，Ｖ２Ｂ２，ＶＮ，Ｖ２Ｎ，ＶＣｘＮ１−ｘ（０＜ｘ＜１），ＮｂＣ，Ｎｂ６Ｃ５，Ｎｂ２Ｃ，ＮｂＢ２，Ｎｂ３Ｂ２，ＮｂＢ，ＮｂＣｘＮ１ −ｘ（０＜ｘ＜１），ＴａＣ，Ｔａ２Ｃ，ＴａＢ２，Ｔａ２Ｂ，Ｔａ３Ｂ２，ＴａＢ，Ｔａ３Ｂ４，ＴａＣｘＮ１−ｘ（０＜ｘ＜１），Ｃｒ３Ｃ２，Ｃｒ２Ｃ，Ｃｒ２３Ｃ６，Ｃｒ７Ｃ３，ＣｒＢ，ＣｒＢ４，Ｃｒ２Ｂ，Ｃｒ２Ｂ３，Ｃｒ５Ｂ３，ＣｒＢ２，Ｃｒ２Ｎ，ＣｒＮ，Ｍｏ２Ｃ，ＭｏＣ，ＭｏＢ，Ｍｏ２Ｂ５，ＭｏＢ４，Ｍｏ２Ｂ，ＭｏＢ２，ＷＣ，Ｗ２Ｃ，ＷＢ４，ＷＮ，Ｗ２Ｎ，これらの固溶体、複化合物、不定比組成の化合物，Ｗ２ＦｅＢ，ＷＦｅＢ，ＭｏＦｅ２Ｂ４，Ｍｏ２Ｆｅ１３Ｂ５，ＭｏＦｅ２Ｂ４，Ｍｏ２ＦｅＢ２，ＴａＮｉＢ２，ＨｆＣｏ３Ｂ２，ＭｏＣｏＢ，Ｍｏ２ＣｏＢ２，ＭｏＣｏ２Ｂ４，ＮｂＣｏＢ２，ＮｂＣｏＢ，Ｎｂ３Ｃｏ４Ｂ７，Ｎｂ２Ｃｏ３Ｂ５，Ｗ３ＣｏＢ３，ＷＣｏＢ，Ｗ２ＣｏＢ２，Ｗ２Ｃｏ２１Ｂ６，ＡｌＢ１２，ＡｌＢ１０，ＡｌＢ２，Ａｌ３Ｂ４８Ｃ２，Ａｌ８Ｂ４Ｃ７，ＡｌＢ１２Ｃ２，及びＡｌＮが挙げられる。
【００１４】
本発明は、試料アセンブリにより限定されることは無く、８００℃から６００℃までの平均冷却速度を２００℃／分以下とすることができる超高圧高温発生装置を用いれば実施することが出来る。冷却以外の条件は得に限定されないが、例えば、焼結条件として、圧力４ＧＰａ〜７．７ＧＰａ、温度１２００℃〜２５００℃程度、保持時間１０／分〜２時間の範囲が好ましく用いられる。
【００１５】
【実施例】
以下に実施例、比較例を掲げて本発明を更に詳しく説明するが、本発明はこれら実施例のみに限定されるものではない。
【００１６】
実施例１：
平均粒径５μｍの立方晶窒化ホウ素粉末９５体積％に、平均粒径１．５μｍのＣｏ粉末を５体積％となるよう秤取し、ボ−ルミルを用いて２４時間湿式混合を行った。混合溶媒にはアセトン（試薬特級）を用いた。混合スラリ−を十／分乾燥し原料粉末とした。この原料粉末を、焼結体とした場合にφ５５×１．２ｍｍｔとなる量だけ秤取し、平均粒径３μｍの炭化タングステン粒子と、１１質量％のＣｏを含有するφ５５×３．８ｔの超硬合金基板とともに超高圧高温焼結装置に装入した。
【００１７】
焼結は、圧力５ＧＰａ、温度１５００℃、保持時間６０／分の条件で行った。焼結終了後、８００℃から６００℃の間を３０℃／分の速度で冷却し、立方晶窒化ホウ素焼結体と超硬合金製基板との一体焼結体を得た。
【００１８】
この焼結体の外周を、ダイヤモンド砥石を用いて５０ｍｍφまで円筒研削し、更に、立方晶窒化ホウ素焼結体層が１ｍｍｔ、超硬合金製基板層が２ｍｍｔとなるまで、ダイヤモンド砥石を用いて平面研削し、変形量測定試料とした。
【００１９】
この変形量測定試料は立方晶窒化ホウ素焼結体層側が凸に変形しており、同試料を定盤上に配置し、定盤から試料面までの高さを、マイクロメ−タ−を用いて測定したところ、試料外周部と試料中央部の高さの差は２μｍだった。
【００２０】
実施例２：
８００℃から６００℃の冷却速度を６０℃／分とした以外は実施例１と同様に実験を行ったところ、得られた試料は立方晶窒化ホウ素焼結体層側が凸に変形しており、同試料の外周部と中央部の高さの差は５μｍだった。
【００２１】
実施例３：
８００℃から６００℃の冷却速度を１００℃／分とした以外は実施例１と同様に実験を行ったところ、得られた試料は立方晶窒化ホウ素焼結体層側が凸に変形しており、同試料の外周部と中央部の高さの差は７μｍだった。
【００２２】
実施例４：
８００℃から６００℃の冷却速度を１５℃／分とした以外は実施例１と同様に実験を行ったところ、得られた試料は立方晶窒化ホウ素焼結体層側が凸に変形しており、同試料の外周部と中央部の高さの差は２μｍだった。
【００２３】
実施例５：
８００℃から６００℃の冷却速度を１０℃／分とした以外は実施例１と同様に実験を行ったところ、得られた試料は立方晶窒化ホウ素焼結体層側が凸に変形しており、同試料の外周部と中央部の高さの差は２μｍだった。
【００２４】
実施例６：
８００℃から６００℃の冷却速度を１５０℃／分とした以外は実施例１と同様に実験を行ったところ、得られた試料は立方晶窒化ホウ素焼結体層側が凸に変形しており、同試料の外周部と中央部の高さの差は１１μｍだった。
【００２５】
実施例７：
８００℃から６００℃の冷却速度を２００℃／分とした以外は実施例１と同様に実験を行ったところ、得られた試料は立方晶窒化ホウ素焼結体層側が凸に変形しており、同試料の外周部と中央部の高さの差は１４μｍだった。
【００２６】
実施例８：
８００℃から６５０℃の間を１５０℃／分の速度で冷却し、、６５０℃で６／分保持、更に６５０℃から６００℃の間を１５０℃／分の速度で冷却した以外は実施例１と同様に実験を行ったところ、得られた試料は立方晶窒化ホウ素焼結体層側が凸に変形しており、同試料の外周部と中央部の高さの差は３μｍだった。
【００２７】
比較例１：
８００℃から６００℃の冷却速度を２５０℃／分とした以外は実施例１と同様に実験を行ったところ、得られた試料は立方晶窒化ホウ素焼結体層側が凸に変形しており、同試料の外周部と中央部の高さの差は４２μｍだった。
【００２８】
比較例２：
８００℃から６００℃の冷却速度を３００℃／分とした以外は実施例１と同様に実験を行ったところ、得られた試料は立方晶窒化ホウ素焼結体層側が凸に変形しており、同試料の外周部と中央部の高さの差は７１μｍだった。
【００２９】
【発明の効果】
本発明の立方晶窒化ホウ素焼結体の製造方法を用いれば、平面研削加工により厚さを減少させても、変形量が小さい立方晶窒化ホウ素焼結体及び超硬合金製基板一体焼結体を得ることが可能となる。これらを用いることにより優れた耐摩耗性を有する切削工具、軸受け、線引ダイス等が得られる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an improvement in a method for producing a cubic boron nitride sintered body having high hardness and excellent wear resistance and being awarded as a wear-resistant material for cutting tools, bearings, drawing dies, and the like.
[0002]
[Prior art]
As a wear-resistant material such as a cutting tool, a tungsten carbide (WC) -based super-hard material has been conventionally used. However, at present, the demands of the customers are becoming more and more severe, and it is becoming difficult to satisfy the demands of the users with the above WC-based cemented carbide materials, and the development of more excellent wear-resistant materials is expected. I have.
[0003]
As a wear-resistant material that meets such demands, cubic boron nitride powder contains a small amount of Al and a metal phase containing at least one of alloying elements selected from the group consisting of Ni, Co, Mn, Fe, and V. A sintered body (JP-A-48-17503) or a cBN sintered body using ceramics as a binder (Japanese Patent Publication No. 57-3631) has been proposed. These sintered bodies are generally sintered integrally with a substrate made of a cemented carbide for the purpose of securing strength as a tool.
[0004]
The integrated sintered body as described above is ground to a predetermined thickness and then cut into a desired shape by electric discharge machining or the like and finished as a tool. In some cases, it is cut into a desired shape by electric discharge machining or the like, and then brazed to a base metal generally made of cemented carbide to finish it as a tool. In any case, in order to put the integrated sintered body into practical use, it is necessary to reduce the thickness by grinding after being taken out of the high-temperature and high-pressure apparatus.
[0005]
On the other hand, the thermal expansion coefficients of these cubic boron nitride sintered bodies and the substrate made of cemented carbide often do not match, and therefore, thermal stress remains in the integrated sintered body. If the thickness of the integrated sintered body in which such thermal stress remains is reduced by grinding, the balance of the stress is lost, so that deformation such as curvature often occurs. Since deformation such as bending becomes an obstacle to subsequent precision processing, development of an integrated sintered body that is unlikely to be deformed even when the thickness is reduced by grinding has been desired.
[0006]
[Problems to be solved by the invention]
Provided are a cubic boron nitride sintered body and a cemented carbide substrate-integrated sintered body that have a small amount of deformation even if the thickness is reduced by surface grinding.
[0007]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors have found that in a method of producing a cubic boron nitride sintered body under high temperature and pressure, cooling from 800 ° C. to 600 ° C. is performed at an average cooling rate of 200 ° C./min or less. The present inventors have found that an integrated sintered body that is less likely to be deformed even when the thickness is reduced by grinding is obtained, and the present invention has been completed.
[0008]
The reason why the manufacturing method of the present invention can provide an integrated sintered body that is less likely to be deformed even when the thickness is reduced by grinding is that cooling from 800 ° C to 600 ° C is performed at an average cooling rate of 200 ° C / min or less. As a result, Co, WC, and the like contained in the cemented carbide move due to rearrangement and the like, and therefore, residual thermal stress due to a difference in thermal expansion coefficient between the cubic boron nitride sintered body and the cemented carbide substrate is relaxed. It is presumed to be.
[0009]
That is, the present invention relates to the following (1) to (11).
(1) A method for producing a cubic boron nitride sintered body under a high temperature and a high pressure, wherein an average cooling rate from 800 ° C. to 600 ° C. after sintering is 200 ° C./min or less. A method for producing a boron nitride sintered body.
(2) The method for producing a cubic boron nitride sintered body according to the above item 1, wherein the average cooling rate from 800 ° C. to 600 ° C. is 30 ° C./min or less.
(3) The method for producing a cubic boron nitride sintered body according to the above item 1, wherein the average cooling rate from 800 ° C to 600 ° C is 10 to 200 ° C / min.
(4) The method for producing a cubic boron nitride sintered body according to the above item 1, wherein the average cooling rate from 800 ° C to 600 ° C is 10 ° C to 30 ° C / min or less.
(5) A cubic boron nitride sintered body obtained by the production method according to any one of the above items 1 to 4.
(6) The cubic boron nitride sintered body according to the above item 5, wherein the cubic boron nitride sintered body contains a binder.
(7) The binder is selected from the group consisting of nitrides, carbides, carbonitrides, borides of IVa to VIa elements, borides of IVa to VIa elements and group VIII elements, and compounds of Al. 7. The cubic boron nitride sintered body according to item 6, which is at least one compound.
(8) The cubic boron nitride sintered body according to the above item 5, wherein the cubic boron nitride sintered body is an integral sintered body with a cemented carbide substrate.
[0010]
(9) A cutting tool using the cubic boron nitride sintered body according to any one of the above items 5 to 8.
(10) A bearing using the cubic boron nitride sintered body according to any one of (5) to (8).
(11) A wire drawing die using the cubic boron nitride sintered body according to any one of the above items 5 to 8.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
In the present invention, the average cooling rate from 800 ° C. to 600 ° C. after sintering is 200 ° C./min or less, preferably 30 ° C./min or less. If the average cooling rate is higher than 200 ° C./min, the relaxation of the residual thermal stress due to the difference in thermal expansion coefficient between the cubic boron nitride sintered body and the substrate made of cemented carbide is insufficient, and the thickness is reduced by grinding. The deformation amount is large, which is not preferable. Although there is no particular lower limit for the average cooling rate, it is preferably 10 ° C./min or more from the viewpoint of production efficiency.
[0012]
The cubic boron nitride sintered body of the present invention may include a binder. Examples of the binder include nitrides, carbides, carbonitrides, borides of IVa, Va, VIa group elements, borides composed of IVa, Va, VIa group elements and VIII group elements, and compounds of Al. Can be
[0013]
Examples of nitrides, carbides, carbonitrides, borides of IVa, Va, VIa group elements, borides composed of IVa, Va, VIa group elements and group VIII elements, and Al compounds include, for example, TiC, TiB 2 , Ti 2 B 5, Ti 3 B 4, TiB, TiN, Ti 2 N, TiC x N 1-x (0 <x <1), ZrC, ZrB 2, ZrB 12, ZrN, ZrC x N 1-x (0 <x <1), HfC, HfB 2, HfB, HfB 12, Hf 3 N 2, HfN, Hf 4 N 3, HfC x N 1-x (0 <x <1), VC, V 4 C 3, V 8 C 7, VB 2, V 3 B 4, V 3 B 12, VB, V 5 B 6, V 2 B 2, VN, V 2 N, VC x N 1-x (0 <x <1), NbC , Nb 6 C 5, Nb 2 C, NbB 2, Nb 3 B 2, Nb , NbC x N 1 -x (0 <x <1), TaC, Ta 2 C, TaB 2, Ta 2 B, Ta 3 B 2, TaB, Ta 3 B 4, TaC x N 1-x (0 <x <1), Cr 3 C 2 , Cr 2 C, Cr 23 C 6, Cr 7 C 3, CrB, CrB 4, Cr 2 B, Cr 2 B 3, Cr 5 B 3, CrB 2, Cr 2 N, CrN , Mo 2 C, MoC, MoB, Mo 2 B 5 , MoB 4 , Mo 2 B, MoB 2 , WC, W 2 C, WB 4 , WN, W 2 N, solid solutions of these, complex compounds, non-stoichiometric compositions Compound, W 2 FeB, WFeB, MoFe 2 B 4 , Mo 2 Fe 13 B 5 , MoFe 2 B 4 , Mo 2 FeB 2 , TaNiB 2 , HfCo 3 B 2 , MoCoB, Mo 2 CoB 2 , MoCo 2 B 4 NbCoB 2 , N bCoB, Nb 3 Co 4 B 7 , Nb 2 Co 3 B 5, W 3 CoB 3, WCoB, W 2 CoB 2, W 2 Co 21 B 6, AlB 12, AlB 10, AlB 2, Al 3 B 48 C 2 , Al 8 B 4 C 7 , AlB 12 C 2 , and AlN.
[0014]
The present invention is not limited by the sample assembly, and can be implemented by using an ultrahigh-pressure high-temperature generator capable of setting the average cooling rate from 800 ° C. to 600 ° C. to 200 ° C./min or less. Conditions other than cooling are not particularly limited, but, for example, sintering conditions preferably include a pressure of 4 GPa to 7.7 GPa, a temperature of about 1200 ° C. to 2500 ° C., and a holding time of 10 / min to 2 hours.
[0015]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to only these Examples.
[0016]
Example 1
Co powder having an average particle size of 1.5 μm was weighed to 95 volume% of cubic boron nitride powder having an average particle size of 5 μm so as to be 5 volume%, and wet-mixed using a ball mill for 24 hours. Acetone (special reagent grade) was used as the mixed solvent. The mixed slurry was dried at a rate of 10 / min to obtain a raw material powder. This raw material powder is weighed in an amount of φ55 × 1.2 mmt when it is made into a sintered body, and tungsten carbide particles having an average particle diameter of 3 μm and a super-size of φ55 × 3.8 t containing 11% by mass of Co. It was charged into an ultra-high pressure and high temperature sintering device together with the hard alloy substrate.
[0017]
The sintering was performed under the conditions of a pressure of 5 GPa, a temperature of 1500 ° C., and a holding time of 60 / min. After the sintering, the temperature was lowered from 800 ° C. to 600 ° C. at a rate of 30 ° C./min to obtain an integrated sintered body of a cubic boron nitride sintered body and a cemented carbide substrate.
[0018]
The outer periphery of this sintered body is cylindrically ground to 50 mmφ using a diamond grindstone. Grinding was performed to obtain a deformation measurement sample.
[0019]
In this deformation amount measurement sample, the cubic boron nitride sintered body layer side is deformed convexly, and the same sample is placed on a surface plate, and the height from the surface plate to the sample surface is measured using a micrometer. As a result of the measurement, the difference in height between the sample outer peripheral portion and the sample central portion was 2 μm.
[0020]
Example 2:
An experiment was performed in the same manner as in Example 1 except that the cooling rate from 800 ° C. to 600 ° C. was set to 60 ° C./min. As a result, the obtained sample had a cubic boron nitride sintered body layer side which was deformed to be convex. The difference in height between the outer peripheral portion and the central portion of the sample was 5 μm.
[0021]
Example 3
An experiment was performed in the same manner as in Example 1 except that the cooling rate from 800 ° C. to 600 ° C. was changed to 100 ° C./min. As a result, the obtained sample had a cubic boron nitride sintered body layer side which was deformed to be convex. The difference in height between the outer peripheral portion and the central portion of the same sample was 7 μm.
[0022]
Example 4:
When an experiment was performed in the same manner as in Example 1 except that the cooling rate from 800 ° C. to 600 ° C. was changed to 15 ° C./min, the obtained sample had a cubic boron nitride sintered body layer side which was deformed to be convex. The difference in height between the outer peripheral portion and the central portion of the sample was 2 μm.
[0023]
Example 5:
An experiment was performed in the same manner as in Example 1 except that the cooling rate from 800 ° C. to 600 ° C. was changed to 10 ° C./min. As a result, the obtained sample had a cubic boron nitride sintered body layer side which was deformed to be convex. The difference in height between the outer peripheral portion and the central portion of the sample was 2 μm.
[0024]
Example 6:
An experiment was carried out in the same manner as in Example 1 except that the cooling rate from 800 ° C. to 600 ° C. was changed to 150 ° C./min. As a result, the obtained sample had a cubic boron nitride sintered body layer side which was deformed to be convex. The difference in height between the outer peripheral portion and the central portion of the sample was 11 μm.
[0025]
Example 7:
When an experiment was performed in the same manner as in Example 1 except that the cooling rate from 800 ° C. to 600 ° C. was 200 ° C./min, the obtained sample had a cubic boron nitride sintered body layer side which was deformed to be convex. The difference in height between the outer peripheral portion and the central portion of the same sample was 14 μm.
[0026]
Example 8:
Example 1 Example 1 except cooling between 800 ° C. and 650 ° C. at a rate of 150 ° C./min, holding at 650 ° C. for 6 / min, and further cooling between 650 ° C. and 600 ° C. at a rate of 150 ° C./min. When the experiment was carried out in the same manner as in the above, the obtained sample had the cubic boron nitride sintered body layer side deformed convexly, and the difference in height between the outer peripheral portion and the central portion of the sample was 3 μm.
[0027]
Comparative Example 1:
An experiment was performed in the same manner as in Example 1 except that the cooling rate from 800 ° C. to 600 ° C. was changed to 250 ° C./min. As a result, the obtained sample had a cubic boron nitride sintered body layer side which was deformed to be convex. The difference in height between the outer peripheral portion and the central portion of the sample was 42 μm.
[0028]
Comparative Example 2:
An experiment was performed in the same manner as in Example 1 except that the cooling rate from 800 ° C. to 600 ° C. was set to 300 ° C./min. As a result, the obtained sample had a cubic boron nitride sintered body layer side which was deformed to be convex, The difference in height between the outer peripheral portion and the central portion of the sample was 71 μm.
[0029]
【The invention's effect】
By using the method for producing a cubic boron nitride sintered body of the present invention, even if the thickness is reduced by surface grinding, the deformation amount is small, and the cubic boron nitride sintered body and the substrate integrated sintered body made of cemented carbide are used. Can be obtained. By using these, cutting tools, bearings, drawing dies and the like having excellent wear resistance can be obtained.
Claims (11)
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2020066087A (en) * | 2018-10-24 | 2020-04-30 | 日東電工株式会社 | End mill manufacturing method |
| CN114198393A (en) * | 2021-12-10 | 2022-03-18 | 四川雄琛科技有限公司 | Bearing of PCBN material |
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2002
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2020066087A (en) * | 2018-10-24 | 2020-04-30 | 日東電工株式会社 | End mill manufacturing method |
| CN112930245A (en) * | 2018-10-24 | 2021-06-08 | 日东电工株式会社 | Method for manufacturing end mill |
| JP7378716B2 (en) | 2018-10-24 | 2023-11-14 | 日東電工株式会社 | End mill manufacturing method |
| CN114198393A (en) * | 2021-12-10 | 2022-03-18 | 四川雄琛科技有限公司 | Bearing of PCBN material |
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