JPH0352430B2 - - Google Patents
Info
- Publication number
- JPH0352430B2 JPH0352430B2 JP23118687A JP23118687A JPH0352430B2 JP H0352430 B2 JPH0352430 B2 JP H0352430B2 JP 23118687 A JP23118687 A JP 23118687A JP 23118687 A JP23118687 A JP 23118687A JP H0352430 B2 JPH0352430 B2 JP H0352430B2
- Authority
- JP
- Japan
- Prior art keywords
- silicon nitride
- sintered body
- aluminum oxide
- coated
- nitride sintered
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 46
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 46
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 34
- 239000010410 layer Substances 0.000 claims description 24
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 claims description 14
- 229910001928 zirconium oxide Inorganic materials 0.000 claims description 14
- 239000010936 titanium Substances 0.000 claims description 13
- 229910052719 titanium Inorganic materials 0.000 claims description 11
- 150000004767 nitrides Chemical class 0.000 claims description 8
- -1 titanium carbides Chemical class 0.000 claims description 8
- SIWVEOZUMHYXCS-UHFFFAOYSA-N oxo(oxoyttriooxy)yttrium Chemical compound O=[Y]O[Y]=O SIWVEOZUMHYXCS-UHFFFAOYSA-N 0.000 claims description 6
- 239000002356 single layer Substances 0.000 claims description 6
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 4
- NRTOMJZYCJJWKI-UHFFFAOYSA-N Titanium nitride Chemical compound [Ti]#N NRTOMJZYCJJWKI-UHFFFAOYSA-N 0.000 claims description 3
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 claims description 2
- WIHZLLGSGQNAGK-UHFFFAOYSA-N hafnium(4+);oxygen(2-) Chemical class [O-2].[O-2].[Hf+4] WIHZLLGSGQNAGK-UHFFFAOYSA-N 0.000 claims description 2
- 229910052726 zirconium Inorganic materials 0.000 claims description 2
- 239000011248 coating agent Substances 0.000 description 15
- 238000000576 coating method Methods 0.000 description 15
- 239000013078 crystal Substances 0.000 description 9
- 238000005520 cutting process Methods 0.000 description 9
- 239000000843 powder Substances 0.000 description 9
- 239000000463 material Substances 0.000 description 7
- 238000000034 method Methods 0.000 description 6
- 239000010408 film Substances 0.000 description 5
- 238000005229 chemical vapour deposition Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000003754 machining Methods 0.000 description 3
- 239000000758 substrate Substances 0.000 description 3
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 239000011247 coating layer Substances 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 239000011777 magnesium Substances 0.000 description 2
- 150000001247 metal acetylides Chemical class 0.000 description 2
- 238000003801 milling Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000035939 shock Effects 0.000 description 2
- 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 2
- 238000007514 turning Methods 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 229910001018 Cast iron Inorganic materials 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000010987 cubic zirconia Substances 0.000 description 1
- 238000000280 densification Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910052735 hafnium Inorganic materials 0.000 description 1
- VBJZVLUMGGDVMO-UHFFFAOYSA-N hafnium atom Chemical compound [Hf] VBJZVLUMGGDVMO-UHFFFAOYSA-N 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- VSZWPYCFIRKVQL-UHFFFAOYSA-N selanylidenegallium;selenium Chemical compound [Se].[Se]=[Ga].[Se]=[Ga] VSZWPYCFIRKVQL-UHFFFAOYSA-N 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 150000003609 titanium compounds Chemical class 0.000 description 1
Landscapes
- Ceramic Products (AREA)
Description
〔産業上の利用分野〕
本発明は耐摩耗性と靭性を兼備した表面被覆窒
化珪素焼結体に関するもので、本発明品はその特
性から工具等の分野に用いて非常に有利である。
〔従来の技術〕
窒化珪素焼結体は、従来の酸化アルミニウム焼
結体等のいわゆるセラミツクス工具部品に比べ、
常温および高温での抗折強度が著しく大きいのに
加えKIC（物質の靭性をあらわす物性値、数値が
大である程靭性が高い）も大巾に改善されてい
る。
加えて、セラミツクス工具の最大の欠点である
熱衝撃に関しても、その目安となる熱衝撃抵抗値
が、窒化珪素は16と酸化アルミニウムの6.5を大
きく上まわつている。
しかしながら、耐摩耗性については酸化アルミ
ニウム系焼結体に比べ劣るため、その使用領域は
今一つ狭かつた。
そこで、その改良として、窒化珪素焼結体の表
面に、窒化珪素よりも硬度の高い酸化アルミニウ
ム等の薄膜を被覆する被覆窒化珪素焼結体が種々
提案され、実用化している。本発明者らが窒化珪
素焼結体に酸化アルミニウムを被覆した被覆窒化
珪素焼結体を用いて実際に切削を行なつてみる
と、被覆しない窒化珪素焼結体に比べ耐摩耗性が
著しく向上した。
〔発明が解決しようとする問題点〕
上記のように、窒化珪素焼結体の表面に酸化ア
ルミニウムを被覆することによつて性能の向上が
見られたが、酸化アルミニウム系焼結体と比較す
ると、まだ耐摩耗性においてかなりの差があり、
工具としての適用領域に制約があつた。
本発明の目的は耐摩耗性が酸化アルミニウム系
焼結体のそれに匹敵するまでに向上し、しかも靭
性に優れた表面被覆窒化珪素焼結体を提供するこ
とにある。
〔問題点を解決するための手段〕
本発明は部分安定化酸化ジルコニウムを含む窒
化珪素焼結体の表面に、チタンの炭化物、窒化
物、炭窒化物、炭酸窒化物のうちの１種または２
種以上の複層を0.1〜0.5μmの層厚で有し、さらに
その上にκ−アルミナを0.4〜1.5μmの層厚で被覆
されてなる表面被覆窒化珪素焼結体を提供する。
本発明における基体の窒化珪素焼結体として
は、部分安定化酸化ジルコニウム３〜10重量％、
酸化アルミニウム１〜５重量％、酸化イツトリウ
ム１〜10重量％及び残部の窒化珪素よりなる焼結
体を用いることが、その耐摩耗性、耐欠損性、高
靭性の点で特に好ましい。
またκ−アルミナがチタン（Ti）、ジルコニウ
ム（Zr）、ハフニウム（Hf）の酸化物の１種また
は２種以上を含有するものであればより有効であ
り好ましい。
さらに、本発明の上記表面被覆窒化珪素焼結体
の最外表面に0.1〜1.5μmの層厚の窒化チタン被覆
を設けることも好ましい。
以下に、本発明に到達した経緯から始めて、本
発明を詳細に説明する。
CVD法（化学蒸着法）で酸化アルミニウム被
覆を形成した場合、被覆温度によつて、結晶構造
の異なるα−酸化アルミニウムまたはκ−酸化ア
ルミニウムが得られることは、既に知られてい
る。
α−酸化アルミニウムは1000℃以上の高温安定
相であるのに対し、κ−酸化アルミニウムは800
〜1000℃で生成される低温安定相である。
そこで、酸化アルミニウムの種類によつて、表
面被覆窒化珪素焼結体の耐摩耗性が異なるのでは
ないかという観点から研究を進め、この２種類の
酸化アルミニウムをそれぞれ被覆した窒化珪素焼
結体を作製して切削を行なつた結果、κ−酸化ア
ルミニウムを被覆した窒化珪素焼結体の方が、α
−酸化アルミニウムを被覆したもの（たとえば特
公昭62−13430号公報に記載のもの）よりも、耐
摩耗性に優れることを見出した。
この理由としては、α−酸化アルミニウムの被
覆には高温を要するのに対して、κ−酸化アルミ
ニウムは1000℃以下の低温で被覆可能であるた
め、結晶粒の成長が抑制され、耐摩耗性に富む微
細な酸化アルミニウムが得られるためと推察でき
る。
したがつて、κ−酸化アルミニウムの被覆は酸
化アルミニウムの全体的な特徴である耐酸化性の
良さ、高温での熱伝導率の低さに加え、その結晶
粒度の細かさが耐摩耗性向上に寄与し、工具にと
つて非常に有効である。
ところで、酸化アルミニウムを窒化珪素焼結体
の表面に直接被覆すると結晶粒が異常成長するこ
とに対し下層として、チタンの炭化物、窒化物、
炭窒化物、炭酸窒化物のうちの１種の単層または
２種以上の複層を窒化珪素焼結体の表面に被覆し
て、さらにこの上に酸化アルミニウムを被覆する
ことにより緻密な酸化アルミニウム被覆を得るこ
とが既に報告されている〔文献：特公昭61−
19367号公報〕。
本発明者らは上記の知見に、この既知技術を応
用して研究を重ねた結果、焼結体表面に施こす上
記のような下層の厚みを0.1〜0.5μmに制御するこ
と、該下層の上に前記した微細結晶のＫ−酸化ア
ルミニウムを0.4〜1.5μmの厚みで被覆することに
より、酸化アルミニウム系焼結体に匹敵する耐摩
耗性を有し、しかも高靭性の表面被覆窒化珪素焼
結体を得ることを見出し、本発明に到達できたの
である。
本発明において基体とする窒化珪素焼結体とし
ては、部分安定化酸化ジルコニウムを含む窒化珪
素焼結体が、耐摩耗性、耐欠損性、靭性に優れ好
ましい。部分安定化酸化ジルコニウムとは、従来
から知られているように、適当量のイツトリウム
（Ｙ）、カルシウム（Ca）、マグネシウム（Mg）
等の酸化物を酸化ジルコニウムに対して３〜８モ
ル％配合し、高温に熱することにより製造でき
る、部分的に立方晶となつた酸化ジルコニウムで
あり、なかでもY2O3で部分安定化させた酸化ジ
ルコニウムが好ましい。
特に好ましい基体の窒化珪素焼結体は、出願人
等が特開昭63−89460号明細書にて出願している、
部分安定化酸化ジルコニウム３〜10重量％と、酸
化アルミニウム１〜５重量％と、酸化イツトリウ
ム１〜10重量％と、及び残部の窒化珪素とからな
る切削工具用窒化珪素焼結体である。
また基体に、前記のチタンの炭化物、窒化物、
炭窒化物、炭酸窒化物の下層と、κ−酸化アルミ
ニウムの上層を被覆し、さらに最外表面層とし
て、0.1〜1.5μmの窒化チタン膜被覆を施したもの
は、特に優れた性能を有する。
以下本発明の被覆窒化珪素焼結体の化学組成お
よび、被覆膜厚の限定理由について説明する。
１） 部分安定化酸化ジルコニウムの含有量は３
〜10重量％の範囲が好ましい。部分安定化酸化
ジルコニウムが３重量％未満では窒化珪素焼結
体の高靭性化の効果が少なく、10重量％を越え
ると窒化珪素焼結体の強度が著しく低下する。
２） 酸化アルミニウムは１〜５重量％、酸化イ
ツトリウムは１〜10重量％の範囲が好ましい。
酸化アルミニウム又は酸化イツトリウムが各々
１重量％未満では焼結体の緻密化が不充分であ
り、酸化アルミニウムが５重量％又は酸化イツ
トリウムが10重量％を超えると焼結体の高温強
度が著しく低下する。
３） チタンの炭化物、窒化物、炭窒化物、炭酸
窒化物のうちの１種の単層または２種以上の複
層を膜厚0.1〜0.5μmで焼結体の表面に被覆して
おく。
窒化珪素焼結体の上に直接酸化アルミニウム
を被覆すると酸化アルミニウムの結晶が異常成
長することはすでに述べたが、下層としてのチ
タンの炭化物、窒化物、炭窒化物、炭酸窒化物
のうちの１種の単層または２種以上の複層の膜
厚が、0.1μm未満では、これらの下層は窒化珪
素焼結体表面で核生成を始めた段階で、まだ窒
化珪素焼結体の全面をおおつていないため、そ
の上に酸化アルミニウムを被覆すると、窒化珪
素焼結体に直接接する部分では酸化アルミニウ
ムの結晶は異常成長し、好ましくない。
一方、チタンの炭化物、窒化物、炭窒化物、
炭酸窒化物のうちの１種の単層または、２種以
上の複層を下層として、その上に、酸化アルミ
ニウムを被覆する際、酸化アルミニウムは下層
の結晶粒界で優先的に核生成するため、微細な
酸化アルミニウムを得るためには下層の結晶も
微細であることが必要である。この観点から、
上述の下層を0.5μm以上の厚みに被覆する（た
とえば特公昭62−13430号公報）と、下層の結
晶粒が成長し粗大化する為その上に被覆する酸
化アルミニウム結晶も粗大化し好ましくない。
なお、下層のチタン化合物とκ−酸化アルミ
ニウムの接着性を改善するために、酸化アルミ
ニウムにチタン、ジルコニウム、ハフニウムの
酸化物の１種以上を含有させると有効である。
４） κ−酸化アルミニウムの膜厚は0.4〜1.5μm
の範囲が好ましい。0.4μm未満では、κ−酸化
アルミニウムの本来の耐摩耗性向上の効果が発
揮されず、1.5μm以上被覆するとκ−酸化アル
ミニウムの結晶粒が粗大化する上、下層との密
着力の低下をまねくため耐摩耗性が低下し好ま
しくない。
本発明の基体となる部分安定化酸化ジルコニウ
ムを含む窒化珪素焼結体は、公知技術により作製
したものでよい。例えばα−Si3N4粉末、Y2O3で
安定化させたZrO2粉末、Al2O3粉末及びY2O3粉
末等の原料粉末を所定の割合で、ボールミル等に
より混合し、プレス成形したのち、N2ガス雰囲
気中で焼結する等の方法である。
また基体の表面に被覆してゆくTi化合物の下
層、κ−酸化アルミニウム層、TiN層等は、公
知のCVD法により形成してゆけばよい。具体的
な例は後記の実施例に示される。
〔実施例〕
実施例 １
市販のα−Si3N4粉末、3mol％Y2O3で部分安
定化させたZrO2粉末、Al2O3粉末及びY2O3粉末
を下記第１表に示す割合で配合し、ボールミルで
粉砕混合し、のちプレス成形した。この成形体を
窒素ガス雰囲気中において1750℃の温度で２時間
常圧焼結し、更に窒素ガス雰囲気中において、
1800℃、1000気圧でHIP処理した。
得られた焼結体を研削加工によつて12.7×12.7
×4.76mmのJIS SNG 433のスローアウエイチツ
プとし、さらにその表面に、CVD法により表１
に示すような所定の層を被覆した。
以上のようにして作製した表面被覆窒化珪素焼
結体工具を用いて、次の４種類のテストを行なつ
た。
（テスト１）
加工方式：旋削
被削材：FC25（HB＝180）
切削速度：400m／min
送り：0.2mm／rev
切込み：２mm
（テスト２）
加工方式：旋削
被削材：FC25（HB＝180）
切削速度：200m／min
送り：0.3mm／rev
切込み：２mm
（テスト３）
加工方式：フライス
被削材：FC25（HB＝200）
切削速度：350m／min
送り：0.15mm／刃
切込み：２mm
（テスト４）
DDI方式：フライス
被削材：FC25（HB＝200）
切削速度：180m／min
送り：0.25mm／刃
切込み：３mm
それぞれのテスト結果を、使用した工具の窒化
珪素焼結体の組成、被覆層の構造、膜厚と共に表
１に示す。本実施例ではチタンの炭窒化物のみ、
炭窒化物及び炭化物の例を示したが、チタンの窒
化物、炭化物、炭酸窒化物のいずれか１種あるい
は、これらの２種以上でも同様に本発明品の寿命
は長いことが確認できた。
[Industrial Field of Application] The present invention relates to a surface-coated silicon nitride sintered body having both wear resistance and toughness, and the product of the present invention is very advantageous for use in the field of tools and the like due to its characteristics. [Prior art] Compared to so-called ceramic tool parts such as conventional aluminum oxide sintered bodies, silicon nitride sintered bodies are
In addition to the significantly high flexural strength at room and high temperatures, the KIC (physical property value that indicates the toughness of a material; the higher the value, the higher the toughness) has also been significantly improved. In addition, regarding thermal shock, which is the biggest drawback of ceramic tools, silicon nitride has a thermal shock resistance value of 16, which is much higher than aluminum oxide's 6.5. However, its wear resistance is inferior to that of aluminum oxide-based sintered bodies, so its range of use is rather narrow. Therefore, as an improvement thereof, various coated silicon nitride sintered bodies have been proposed and put into practical use, in which the surface of the silicon nitride sintered body is coated with a thin film of aluminum oxide or the like, which is harder than silicon nitride. When the present inventors actually performed cutting using a coated silicon nitride sintered body in which a silicon nitride sintered body was coated with aluminum oxide, the wear resistance was significantly improved compared to an uncoated silicon nitride sintered body. did. [Problems to be solved by the invention] As mentioned above, performance was improved by coating the surface of the silicon nitride sintered body with aluminum oxide, but compared to the aluminum oxide-based sintered body, the performance was improved. , there is still a considerable difference in wear resistance,
There were restrictions on the range of application as a tool. An object of the present invention is to provide a surface-coated silicon nitride sintered body with improved wear resistance comparable to that of an aluminum oxide-based sintered body and excellent toughness. [Means for Solving the Problems] The present invention provides one or two of titanium carbides, nitrides, carbonitrides, and carbonitrides on the surface of a silicon nitride sintered body containing partially stabilized zirconium oxide.
Provided is a surface-coated silicon nitride sintered body having a multilayer of 0.1 to 0.5 μm in thickness and further coated with κ-alumina in a layer thickness of 0.4 to 1.5 μm. The silicon nitride sintered body of the base in the present invention includes 3 to 10% by weight of partially stabilized zirconium oxide,
It is particularly preferable to use a sintered body consisting of 1 to 5% by weight of aluminum oxide, 1 to 10% by weight of yttrium oxide, and the remainder silicon nitride, in terms of its wear resistance, chipping resistance, and high toughness. Further, it is more effective and preferable if the κ-alumina contains one or more of titanium (Ti), zirconium (Zr), and hafnium (Hf) oxides. Furthermore, it is also preferable to provide a titanium nitride coating with a layer thickness of 0.1 to 1.5 μm on the outermost surface of the surface-coated silicon nitride sintered body of the present invention. In the following, the present invention will be explained in detail, starting from how the invention was arrived at. It is already known that when an aluminum oxide coating is formed by CVD (chemical vapor deposition), α-aluminum oxide or κ-aluminum oxide having different crystal structures can be obtained depending on the coating temperature. α-aluminum oxide is a stable phase at temperatures above 1000℃, while κ-aluminum oxide is stable at temperatures above 800℃.
It is a low temperature stable phase produced at ~1000℃. Therefore, we conducted research from the perspective of whether the wear resistance of surface-coated silicon nitride sintered bodies differs depending on the type of aluminum oxide, and developed silicon nitride sintered bodies coated with these two types of aluminum oxide. As a result of fabrication and cutting, it was found that the silicon nitride sintered body coated with κ-aluminum oxide has a higher α
- It has been found that the wear resistance is superior to that coated with aluminum oxide (for example, the one described in Japanese Patent Publication No. 13430/1983). The reason for this is that coating α-aluminum oxide requires high temperatures, whereas κ-aluminum oxide can be coated at a low temperature below 1000°C, which suppresses the growth of crystal grains and improves wear resistance. This can be inferred to be due to the fact that rich and fine aluminum oxide can be obtained. Therefore, in addition to the overall characteristics of aluminum oxide, such as good oxidation resistance and low thermal conductivity at high temperatures, the coating of κ-aluminum oxide has fine grain size that improves wear resistance. It is very useful for tools. By the way, if aluminum oxide is directly coated on the surface of a silicon nitride sintered body, crystal grains will grow abnormally, but titanium carbide, nitride,
By coating the surface of a silicon nitride sintered body with a single layer or a multilayer of two or more of carbonitrides and carbonitrides, and further coating aluminum oxide on this, dense aluminum oxide can be obtained. It has already been reported that a coating can be obtained [Reference: Japanese Patent Publication No. 61-
Publication No. 19367]. The present inventors applied this known technology to the above findings and conducted repeated research. As a result, they found that the thickness of the above-mentioned lower layer applied to the surface of the sintered body was controlled to 0.1 to 0.5 μm, and the thickness of the lower layer was 0.1 to 0.5 μm. By coating the above-mentioned microcrystalline K-aluminum oxide with a thickness of 0.4 to 1.5 μm, the surface-coated silicon nitride sintered material has wear resistance comparable to that of aluminum oxide-based sintered bodies and has high toughness. The present invention was achieved by discovering that the present invention can be obtained by using the same method. As the silicon nitride sintered body used as a base in the present invention, a silicon nitride sintered body containing partially stabilized zirconium oxide is preferable because of its excellent wear resistance, chipping resistance, and toughness. As is conventionally known, partially stabilized zirconium oxide contains appropriate amounts of ythtrium (Y), calcium (Ca), and magnesium (Mg).
It is a partially cubic zirconium oxide that can be produced by blending 3 to 8 mol% of oxides such as zirconium oxide and heating it to a high temperature, and is partially stabilized with Y 2 O 3 . zirconium oxide is preferred. A particularly preferable silicon nitride sintered body as a substrate is disclosed in Japanese Patent Application Laid-Open No. 63-89460 by the applicants.
This is a silicon nitride sintered body for a cutting tool, comprising 3 to 10% by weight of partially stabilized zirconium oxide, 1 to 5% by weight of aluminum oxide, 1 to 10% by weight of yttrium oxide, and the balance silicon nitride. In addition, the substrate may contain the above-mentioned titanium carbide, nitride,
Particularly excellent performance is achieved by coating a lower layer of carbonitride or carbonitride, an upper layer of κ-aluminum oxide, and further coating with a titanium nitride film of 0.1 to 1.5 μm as the outermost surface layer. The chemical composition of the coated silicon nitride sintered body of the present invention and the reason for limiting the coating film thickness will be explained below. 1) The content of partially stabilized zirconium oxide is 3
A range of 10% by weight is preferred. When the content of partially stabilized zirconium oxide is less than 3% by weight, the effect of increasing the toughness of the silicon nitride sintered body is small, and when it exceeds 10% by weight, the strength of the silicon nitride sintered body is significantly reduced. 2) The aluminum oxide content is preferably 1 to 5% by weight, and the yttrium oxide content is preferably 1 to 10% by weight.
If aluminum oxide or yttrium oxide is less than 1% by weight each, the densification of the sintered body is insufficient, and if aluminum oxide exceeds 5% by weight or yttrium oxide exceeds 10% by weight, the high temperature strength of the sintered body is significantly reduced. . 3) The surface of the sintered body is coated with a single layer or a multilayer of two or more of titanium carbides, nitrides, carbonitrides, and carbonitrides with a film thickness of 0.1 to 0.5 μm. It has already been mentioned that if aluminum oxide is directly coated on a silicon nitride sintered body, aluminum oxide crystals will grow abnormally, but one of titanium carbides, nitrides, carbonitrides, and carbonitrides as the lower layer. If the film thickness of the single layer or multiple layers of two or more species is less than 0.1 μm, these lower layers will not cover the entire surface of the silicon nitride sintered body at the stage where nucleation has started on the surface of the silicon nitride sintered body. Therefore, if aluminum oxide is coated thereon, aluminum oxide crystals will grow abnormally in the portion directly in contact with the silicon nitride sintered body, which is undesirable. On the other hand, titanium carbides, nitrides, carbonitrides,
When aluminum oxide is coated on a single layer of one type of carbonate nitride or a multiple layer of two or more types as a lower layer, aluminum oxide preferentially nucleates at the grain boundaries of the lower layer. In order to obtain fine aluminum oxide, the underlying crystals must also be fine. From this point of view,
If the above-mentioned lower layer is coated to a thickness of 0.5 μm or more (for example, Japanese Patent Publication No. 13430/1982), the crystal grains in the lower layer will grow and become coarse, which is not preferable because the aluminum oxide crystals coated thereon will also become coarse. In order to improve the adhesion between the lower layer titanium compound and κ-aluminum oxide, it is effective to include one or more of titanium, zirconium, and hafnium oxides in aluminum oxide. 4) Film thickness of κ-aluminum oxide is 0.4 to 1.5 μm
A range of is preferred. If it is less than 0.4 μm, the original wear resistance improvement effect of κ-aluminum oxide will not be exhibited, and if it is coated with a thickness of 1.5 μm or more, the crystal grains of κ-aluminum oxide will become coarse and the adhesion with the underlying layer will decrease. Therefore, wear resistance decreases, which is not preferable. The silicon nitride sintered body containing partially stabilized zirconium oxide serving as the base of the present invention may be produced by a known technique. For example, raw material powders such as α-Si 3 N 4 powder, ZrO 2 powder stabilized with Y 2 O 3 , Al 2 O 3 powder, and Y 2 O 3 powder are mixed in a predetermined ratio using a ball mill, etc., and then pressed. After molding, the material is sintered in an N2 gas atmosphere. Further, the lower layer of the Ti compound, the κ-aluminum oxide layer, the TiN layer, etc. to be coated on the surface of the substrate may be formed by a known CVD method. Specific examples are shown in Examples below. [Example] Example 1 Commercially available α-Si 3 N 4 powder, ZrO 2 powder partially stabilized with 3 mol% Y 2 O 3 , Al 2 O 3 powder and Y 2 O 3 powder are shown in Table 1 below. They were blended in the proportions shown, pulverized and mixed in a ball mill, and then press-molded. This molded body was sintered under normal pressure in a nitrogen gas atmosphere at a temperature of 1750°C for 2 hours, and further in a nitrogen gas atmosphere.
HIP treatment was performed at 1800℃ and 1000 atm. The obtained sintered body was ground to 12.7×12.7
×4.76mm JIS SNG 433 throw-away chip, and the surface is coated with Table 1 by CVD method.
A predetermined layer was coated as shown in FIG. Using the surface-coated silicon nitride sintered tool produced as described above, the following four types of tests were conducted. (Test 1) Machining method: Turning Work material: FC25 (H B = 180) Cutting speed: 400 m/min Feed: 0.2 mm/rev Depth of cut: 2 mm (Test 2) Machining method: Turning Work material: FC25 (H B = 180) Cutting speed: 200m/min Feed: 0.3mm/rev Depth of cut: 2mm (Test 3) Machining method: Milling Work material: FC25 (H B = 200) Cutting speed: 350m/min Feed: 0.15mm/blade Depth of cut : 2mm (Test 4) DDI method: Milling Work material: FC25 (H B = 200) Cutting speed: 180m/min Feed: 0.25mm/tooth Depth of cut: 3mm The results of each test are based on the silicon nitride sintering of the tool used. Table 1 shows the composition of the body, the structure of the coating layer, and the thickness of the coating layer. In this example, only titanium carbonitride was used.
Although examples of carbonitrides and carbides have been shown, it was confirmed that the life of the product of the present invention is similarly long even when one or more of titanium nitrides, carbides, and carbonitrides are used.
以上説明のように、本発明は部分安定化酸化ジ
ルコニウムを含む窒化珪素焼結体の表面に、チタ
ンの炭化物、窒化物、炭窒化物、炭酸窒化物のう
ちの１種の単層または２種以上の複層を0.1〜
0.5μmの層厚で被覆し、さらにその上にκ−酸化
アルミニウムを0.4〜1.5μmの層厚で被覆すること
によつて、靭性及び耐摩耗性に富んだ表面被覆窒
化珪素焼結体を提供することに成功したものであ
る。
本発明の被覆窒化珪素焼結体を切削工具として
用いれば、鋳鉄を中〜高速の巾広い切削条件で切
削することが可能となるので、本発明の産業上に
寄与する意義は大である。
As explained above, the present invention provides a single layer or two types of titanium carbides, nitrides, carbonitrides, and carbonitrides on the surface of a silicon nitride sintered body containing partially stabilized zirconium oxide. More than 0.1~
By coating with a layer thickness of 0.5 μm and further coating with κ-aluminum oxide with a layer thickness of 0.4 to 1.5 μm, a surface-coated silicon nitride sintered body with high toughness and wear resistance is provided. It was successful in doing so. If the coated silicon nitride sintered body of the present invention is used as a cutting tool, it becomes possible to cut cast iron under a wide range of cutting conditions from medium to high speed, so the industrial significance of the present invention is significant.
Claims (1)
焼結体の表面に、チタンの炭化物、窒化物、炭窒
化物、炭酸窒化物のうちの１種の単層または２種
以上の複層を0.1〜0.5μmの層厚で有し、さらにそ
の上にκ−アルミナを0.4〜1.5μmの層厚で被覆さ
れてなる表面被覆窒化珪素焼結体であつて、該窒
化珪素焼結体が部分安定化酸化ジルコニウム３〜
10重量％、酸化アルミニウム１〜５重量％、酸化
イツトリウム１〜10重量％及び残部の窒化珪素よ
りなることを特徴とする上記焼結体。 ２ κ−アルミナがチタン、ジルコニウム、ハフ
ニウムの酸化物の１種または２種以上を含有する
ものである特許請求の範囲第１項に記載の表面被
覆窒化珪素焼結体。 ３ 最外表面に0.1〜0.5μmの層厚の窒化チタンを
被覆されてなる特許請求の範囲第１項ないし第２
項のいずれかに記載の表面被覆窒化珪素焼結体。[Claims] 1. On the surface of a silicon nitride sintered body containing partially stabilized zirconium oxide, a single layer or two or more of titanium carbides, nitrides, carbonitrides, and carbonitrides are formed. A surface-coated silicon nitride sintered body having a multilayer layer with a layer thickness of 0.1 to 0.5 μm and further coated with κ-alumina with a layer thickness of 0.4 to 1.5 μm, the silicon nitride sintered body Body partially stabilized zirconium oxide 3~
10% by weight of aluminum oxide, 1-5% by weight of aluminum oxide, 1-10% by weight of yttrium oxide, and the balance silicon nitride. 2. The surface-coated silicon nitride sintered body according to claim 1, wherein the κ-alumina contains one or more of titanium, zirconium, and hafnium oxides. 3 Claims 1 to 2 in which the outermost surface is coated with titanium nitride with a layer thickness of 0.1 to 0.5 μm.
2. The surface-coated silicon nitride sintered body according to any one of Items 1 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23118687A JPS6476989A (en) | 1987-09-17 | 1987-09-17 | Sintered material of silicon nitride having coated surface |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23118687A JPS6476989A (en) | 1987-09-17 | 1987-09-17 | Sintered material of silicon nitride having coated surface |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6476989A JPS6476989A (en) | 1989-03-23 |
| JPH0352430B2 true JPH0352430B2 (en) | 1991-08-09 |
Family
ID=16919673
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP23118687A Granted JPS6476989A (en) | 1987-09-17 | 1987-09-17 | Sintered material of silicon nitride having coated surface |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6476989A (en) |
-
1987
- 1987-09-17 JP JP23118687A patent/JPS6476989A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6476989A (en) | 1989-03-23 |
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