JPH0653609B2 - Manufacturing method of high toughness silicon nitride sintered body - Google Patents
Manufacturing method of high toughness silicon nitride sintered bodyInfo
- Publication number
- JPH0653609B2 JPH0653609B2 JP63030058A JP3005888A JPH0653609B2 JP H0653609 B2 JPH0653609 B2 JP H0653609B2 JP 63030058 A JP63030058 A JP 63030058A JP 3005888 A JP3005888 A JP 3005888A JP H0653609 B2 JPH0653609 B2 JP H0653609B2
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- silicon nitride
- sintered body
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- nitride sintered
- high toughness
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Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、靱性の高い窒化珪素焼結体の製法に関するも
ので、エンジニアリングセラミツクスとして各種の機械
部品や自動車部品等に有用なものである。TECHNICAL FIELD The present invention relates to a method for producing a silicon nitride sintered body having high toughness, and is useful as various engineering parts such as mechanical parts and automobile parts as engineering ceramics.
セラミツクスの本質的な性質である脆さを改善するため
の方法はこれまで幾つか提案されている。複合化による
方法は代表的なもので、ウイスカー、繊維、粒子などの
混合・分散による破壊靱性の向上がある。例えば、窯業
協会発行、「特集セラミツクスの強靱化に挑む」セラミ
ツクスVol.２１NO.７ １９８６年７月号に記されてい
る。現在、窒化珪素焼結体の高靱化にはウイスカー添加
が最も有効と見られる。Several methods have been proposed so far for improving brittleness, which is an essential property of ceramics. The composite method is a typical method, and the fracture toughness can be improved by mixing and dispersing whiskers, fibers, particles and the like. For example, it is described in "Special Issue on Strengthening Ceramics", Ceramics Vol.21 NO.7, July, 1986, published by Ceramic Industry Association. At present, addition of whiskers seems to be the most effective for increasing the toughness of a silicon nitride sintered body.
しかしながら、複合化による強靱化を行うには均一な分
散が要求される。特にウイスカー、繊維は分散が難しく
湿式ボールミル等で長時間混合しなければならないばか
りでなく、完全な均一分散は実質的に不可能に近い。ま
た、スリツプキヤスト、射出成形等の成形方法も困難と
なる。さらには、ウイスカー、繊維を混入したものを焼
結することは難しく、たとえホツトプレス法であつても
理論密度近くにするのは容易ではない。However, a uniform dispersion is required to strengthen the composite. In particular, whiskers and fibers are difficult to disperse, and not only must they be mixed for a long time with a wet ball mill, but complete uniform dispersion is practically impossible. Also, molding methods such as slip casting and injection molding become difficult. Furthermore, it is difficult to sinter those containing whiskers and fibers, and even with the hot press method, it is not easy to bring the density close to the theoretical density.
本発明は以上のような問題点を解決し、比較的容易に高
靱性の窒化珪素焼結体を得ようとするものである。The present invention intends to solve the above problems and to relatively easily obtain a high toughness silicon nitride sintered body.
すなわち、本発明は、平均粒径５μｍ以下の窒化珪素粉
末を主成分としMgO及び／又はMgAl2O4からなる焼結助剤
０．２〜５容量％と平均粒径１．５〜１０μｍのCr3C2
粉末１〜５０容量％とを含んでなる混合粉末を成形・焼
結することを特徴とする高靱性窒化珪素焼結体の製法で
ある。That is, according to the present invention, a sintering aid of which main component is silicon nitride powder having an average particle size of 5 μm or less and which is made of MgO and / or MgAl 2 O 4 and has an average particle size of 1.5 to 10 μm. Cr 3 C 2
A method for producing a high toughness silicon nitride sintered body, which comprises molding and sintering a mixed powder containing 1 to 50% by volume of powder.
以下、さらに詳しく本発明について説明する。The present invention will be described in more detail below.
複合化による破壊靱性向上の主な機構として、クラツプ
・デイフレクシヨン、マイクロクラツキング、応力誘起
変態、プルアウトなどが考えられるが、本発明の方法に
おいては、クラツプ・デイフレクシヨンとマイクロクラ
ツキングが重要である。クラツク・デイフレクシヨン
は、マトリツクスと分散相の靱性や熱膨張率などの物性
の相違や両者の界面状態などが原因となつてクラツクが
分散粒子の周りをジグザグに折れ曲つて進むことにより
エネルギーが散逸するものである。また、マイクロクラ
ツキングも分散相とマトリツクスの熱膨張率の差などに
よつて分散粒子の周りに歪みが生じ、多数のクラツクが
発生し、主クラツク先端が微細クラツクの生じた領域に
進むと、微細クラツク同士が結合して成長したり、新し
く微細クラツクが発生したりしてこの領域の弾性率が低
下する。そのため、主クラツク先端にかかる応力が減少
するものである。As the main mechanism for improving fracture toughness by compounding, it is possible to consider clasp diffraction, microcracking, stress-induced transformation, pull-out, etc., but in the method of the present invention, clapp diffraction and microclutch King is important. The crack day flexion causes energy to increase as the crack bends around the dispersed particles in a zigzag manner due to differences in the physical properties such as the toughness and the coefficient of thermal expansion of the matrix and the dispersed phase, and the interfacial state between the two. It is dissipated. Also, in microcracking, distortion occurs around the dispersed particles due to the difference in the coefficient of thermal expansion between the dispersed phase and the matrix, and a large number of cracks are generated. As a result, fine cracks are bonded to each other to grow, or new fine cracks are generated, so that the elastic modulus in this region is lowered. Therefore, the stress applied to the tip of the main crack is reduced.
すなわち、本発明は、窒化珪素焼結体中に炭化クロム粒
子を適度に分散させることにより靱性の大幅な改善を可
能としたものである。That is, the present invention makes it possible to significantly improve the toughness by appropriately dispersing the chromium carbide particles in the silicon nitride sintered body.
本発明で使用される窒化珪素Si3N4粉末の平均粒径は５
μｍ以下であることを要し、５μｍを越えては靱性の改
良は認められない。好ましい平均粒径は３μｍ以下特に
１μｍ以下である。The average particle size of the silicon nitride Si 3 N 4 powder used in the present invention is 5
It is necessary to be less than μm, and if it exceeds 5 μm, improvement in toughness is not recognized. A preferable average particle size is 3 μm or less, particularly 1 μm or less.
焼結助剤としては、MgO及び／又はMgAl2O4を０．２〜５
容量％存在させる。０．２容量％未満では焼結効果は少
なく、また、５容量％を越えると強度が低下する。MgO
を成分として含有しない焼結助剤、例えばAl2O3-Y2O3系
では高靱性化は達成できない。なお、本発明において
は、MgSiO4、MgSiO3、Mg(OH)2、Mg(NO3)2、MgSO4、コーディ
エライト等のMgO化合物、さらにはAl2O3、Y2O3、CoAl2O4、
ZrO2、SiO2等の焼結助剤と併用することもでき、その割
合は、０．２〜５容量％程度である。As a sintering aid, MgO and / or MgAl 2 O 4 is used in an amount of 0.2 to 5
It is present by volume%. If it is less than 0.2% by volume, the sintering effect is small, and if it exceeds 5% by volume, the strength decreases. MgO
Sintering aids that do not contain as a component, such as the Al 2 O 3 —Y 2 O 3 system, cannot achieve high toughness. In the present invention, MgSiO 4 , MgSiO 3 , Mg (OH) 2 , Mg (NO 3 ) 2 , MgSO 4 , MgO compounds such as cordierite, and further Al 2 O 3 , Y 2 O 3 , CoAl. 2 O 4 ,
It can be used in combination with a sintering aid such as ZrO 2 or SiO 2 , and the ratio thereof is about 0.2 to 5% by volume.
高靱性化のための分散粒子は種々検討した結果、炭化ク
ロムCr3O2が最も良好であることが判つた。この理由に
ついては定かではないが、Cr3C2の熱膨張係数は１０〜
１１×１０−６／℃でSi3N4の２〜３×１０−６／℃と
比べ３倍以上であり、融点はCr3C2が１８１０℃でSi3N4
の１８９０℃と比較的近いことにもとづいているものと
考えている。As a result of various studies on dispersed particles for increasing the toughness, it was found that chromium carbide Cr 3 O 2 was the best. The reason for this is not clear, but the coefficient of thermal expansion of Cr 3 C 2 is 10 to 10.
It is 3 × 10 −6 / ° C. or more than 3 times that of Si 3 N 4 at 11 × 10 −6 / ° C., and the melting point of Si 3 N 4 is 1810 ° C. for Cr 3 C 2.
I think that it is based on the fact that it is relatively close to 1890 ° C.
Cr3C2の平均粒径は１．５〜１０μｍであり、これ以外
では高い靱性は得られない。好ましくは３〜６μｍであ
る。また、混合粉末中のCr3C2の含有量は１〜５０容量
％である。１容量％未満では靱性の向上は認められず、
また、５０容量％を越えては強度等の物性が低下する。The average grain size of Cr 3 C 2 is 1.5 to 10 μm, and otherwise high toughness cannot be obtained. It is preferably 3 to 6 μm. The content of Cr 3 C 2 in the mixed powder is 1 to 50% by volume. If less than 1% by volume, no improvement in toughness is observed,
Further, if it exceeds 50% by volume, the physical properties such as strength deteriorate.
Si3N4粉末、焼結助剤、Cr3C2粉末の混合は、ボールミル
等の混合機を用い、湿式あるいは乾式で行われる。成形
・焼結方法とは、一般に、常圧焼結、ホツトプレス、HI
Pなどが考えられるが、本発明ではホツトプレスが最も
好しい。焼結条件は、非酸化性雰囲気下、温度１４００
〜１７００℃特に１５００〜１６００℃、圧力１００〜
４００kg/cm2、時間は１〜３時間程度が好ましい。本発
明においては、焼結温度が比較的重要であり、１４００
℃未満では充分な焼結密度は得られ難く、また、１７０
０℃を越えると強度低下する。The Si 3 N 4 powder, the sintering aid, and the Cr 3 C 2 powder are mixed in a wet or dry manner using a mixer such as a ball mill. Molding and sintering methods are generally pressureless sintering, hot pressing, HI
Although P and the like are possible, the hot press is the most preferable in the present invention. The sintering conditions are a temperature of 1400 in a non-oxidizing atmosphere.
~ 1700 ° C, especially 1500 ~ 1600 ° C, pressure 100 ~
400 kg / cm 2 , and the time is preferably about 1 to 3 hours. In the present invention, the sintering temperature is relatively important.
If the temperature is less than ℃, it is difficult to obtain a sufficient sintered density.
When the temperature exceeds 0 ° C, the strength decreases.
破壊靱性値KICの測定法には種々あるが、本発明ではIM
(Indentaion Micro fracture)法を採用する。これは、
“昭和５９年度通商産業省工業技術院委託フアインセラ
ミツクスの標準化に関する調査研究報告書昭和６０年３
月フアインセラミツクス協会”に記載されている測定法
であり、試料の鏡面研磨、圧子圧入、クラツク長さ測
定、経験式を用いたKICの算出の４つの過程からなる。
すなわち、表面研磨した試料にビツカース圧子を圧入す
る。装置はビツカースやヌープ硬度計を用いる。試料に
発生したクラツクの長さを光学顕微鏡あるいはSEMを用
いて測定するものである。KICを算出する経験式は数多
くあるが、本発明では次式を用いた。There are various methods for measuring the fracture toughness value K IC , but in the present invention, IM
(Indentaion Micro fracture) method is adopted. this is,
"A survey research report on the standardization of fine ceramics entrusted by the Agency of Industrial Science and Technology, Ministry of International Trade and Industry in 1984, March 1985.
This is a measurement method described in "Monthly Fine Ceramics Association" and consists of four processes: mirror polishing of sample, indentation, indentation measurement, crack length measurement, and K IC calculation using empirical formula.
That is, a Vitzkers indenter is pressed into the surface-polished sample. The device uses a Vitzkers or Knoop hardness tester. The length of cracks generated in the sample is measured using an optical microscope or SEM. Although there are many empirical formulas for calculating K IC , the following formula was used in the present invention.
(KICφ／Ha1/2)(H/Eφ）2/5＝0.129(c/a)-3/2 Ｅ…ヤング率、Ｈ…硬度、ａ…圧痕長さ、ｃ…亀裂長
さ、φ＝３、荷重は２０kg、荷重印加時間１５秒間 各種セラミツクスの破壊靱性値KIC(MPa・m1/2)は、一般
に、Si3N4４〜６、SiC３〜５、Al2O3３〜５、部分安定
化ZrO2(PSZ)７〜１０、ガラス0.75、WC-Co合金１２〜１
６、アルミ合金３４と言われている。本発明によれば、
これを７以上にすることができるものである。(K IC φ / Ha 1/2 ) (H / E φ) 2/5 = 0.129 (c / a) -3/2 E ... Young's modulus, H ... Hardness, a ... Indentation length, c ... Crack length, φ = 3, load 20 kg, load application time 15 seconds The fracture toughness value K IC (MPa · m 1/2 ) of various ceramics is generally Si 3 N 4 4-6, SiC 3-5, Al 2 O 3 3 ~ 5, partially stabilized ZrO 2 (PSZ) 7 ~ 10, glass 0.75, WC-Co alloy 12 ~ 1
6. It is said to be aluminum alloy 34. According to the invention,
This can be set to 7 or more.
以下、実施例をあげてさらに具体的に本発明を説明す
る。Hereinafter, the present invention will be described more specifically with reference to examples.
実施例１ 表−１に示す種々の容量％の焼結助剤MgO、MgAl2O4、Al2O
3、Y2O3及び平均粒径5.0μｍのCr3C2粉末１５容量％を平
均粒径0.6μｍのSi3N4粉末（電気化学工業社製SN-GD
３）に混合して全体を１００容量％の混合粉末を調製し
た。これを、１５５０℃、２時間、３００kg/cm2の条件
でホツトプレス法により焼結体を得、破壊靱性値KICを
測定した。その結果を表−１に示す。Example 1 Various volume% sintering aids MgO, MgAl 2 O 4 , Al 2 O shown in Table 1
3 , 3 % of Y 2 O 3 and 15% by volume of Cr 3 C 2 powder having an average particle size of 5.0 μm were added to Si 3 N 4 powder having an average particle size of 0.6 μm (SN-GD manufactured by Denki Kagaku Kogyo Co., Ltd.
3) was mixed to prepare a mixed powder of 100% by volume as a whole. This was sintered at 1550 ° C. for 2 hours under the conditions of 300 kg / cm 2 by a hot press method to obtain a sintered body, and the fracture toughness value K IC was measured. The results are shown in Table-1.
実施例２ 表−１の実験NO.９において、Cr3C2１５容量％のかわり
に表−２に示す容積のCr3C2をSi3N4粉末に置きかえて使
用したこと以外は同様の条件で焼結体を作製し破壊靱性
値KICを測定した。その結果を表−２に示す。 Example 2 In Experiment No. 9 of Table-1, the same as in Example 3 except that Cr 3 C 2 having a volume shown in Table 2 was replaced with Si 3 N 4 powder instead of Cr 3 C 2 15% by volume. A sintered body was prepared under the conditions and the fracture toughness value K IC was measured. The results are shown in Table-2.
実施例３ 表−１の実験NO.９において、Si3N4粉末とCr3C2粉末の
平均粒径を表−３に示すように変えた以外は同様の条件
で焼結体を作製し、破壊靱性値KICを測定した。その結
果を表−３に示す。 Example 3 In Experiment No. 9 of Table-1, a sintered body was produced under the same conditions except that the average particle size of Si 3 N 4 powder and Cr 3 C 2 powder was changed as shown in Table-3. The fracture toughness value K IC was measured. The results are shown in Table-3.
実施例４ 表−１の実験NO.９に示した配合組成についてホツトプ
レスの焼結条件を変えて焼結体を作製し、相対密度、破
壊靱性値KIC及び常温曲げ強度を測定した。それらの結
果を表−４に示す。 Example 4 With respect to the compounding composition shown in Experiment No. 9 of Table-1, a sintered body was prepared by changing the sintering conditions of the hot press, and the relative density, the fracture toughness value K IC and the room temperature bending strength were measured. The results are shown in Table-4.
以上の実施例から次のことがわかる。 The following can be understood from the above-described examples.
(1)実施例１から、MgO及び／又はMgAl2O4からなる焼結
助剤の添加量は０．２容量％以上５容量％以下が適切で
ある。中でも、MgAl2O4+Al2O3系が最も高KICを示した。
Al2O3+Y2O3系は最も低いがMgOを加えることによりKICは
向上する。(1) From Example 1, it is appropriate that the addition amount of the sintering aid made of MgO and / or MgAl 2 O 4 is 0.2% by volume or more and 5% by volume or less. Among them, the MgAl 2 O 4 + Al 2 O 3 system showed the highest K IC .
Al 2 O 3 + Y 2 O 3 system is the lowest, but the addition of MgO improves the K IC .
(2)実施例２から、Cr3C2粒子が１容量％以上５０容量％
以下で7.5〜10.2MPa・m1/2のKICが得られる。(2) From Example 2, Cr 3 C 2 particles are 1% by volume or more and 50% by volume.
A K IC of 7.5 to 10.2 MPa · m 1/2 is obtained below.
(3)実施例３にはSi3N4とCr3C2の平均粒子の粒径の影響
が示されており、Si3N4は5.0μｍ以下、Cr3C2は1.5μｍ
以上１０μｍ以下が適切である。(3) In Example 3, the influence of the average particle size of Si 3 N 4 and Cr 3 C 2 is shown. Si 3 N 4 is 5.0 μm or less and Cr 3 C 2 is 1.5 μm.
Above 10 μm is appropriate.
(4)実施例４から焼結温度は１５００〜１６００℃にお
いて最も良好な靱性と強度が得られる。(4) From Example 4, the best toughness and strength are obtained at a sintering temperature of 1500 to 1600 ° C.
本発明の方法によれば、簡単に高靱性の窒化珪素焼結体
を製造することができる。According to the method of the present invention, a high toughness silicon nitride sintered body can be easily manufactured.
Claims (1)
分としMgO及び／又はMgAl2O4からなる焼結助剤０．２〜
５容量％と平均粒径１．５〜１０μｍのCr3C2粉末１〜
５０容量％とを含んでなる混合粉末を成形・焼結するこ
とを特徴とする高靱性窒化珪素焼結体の製法。1. A sintering aid of which the main component is silicon nitride powder having an average particle size of 5 μm or less and which is composed of MgO and / or MgAl 2 O 4
Cr 3 C 2 powder 1 with 5% by volume and an average particle size of 1.5 to 10 μm
A method for producing a high toughness silicon nitride sintered body, which comprises molding and sintering a mixed powder containing 50% by volume.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63030058A JPH0653609B2 (en) | 1988-02-13 | 1988-02-13 | Manufacturing method of high toughness silicon nitride sintered body |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63030058A JPH0653609B2 (en) | 1988-02-13 | 1988-02-13 | Manufacturing method of high toughness silicon nitride sintered body |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01208369A JPH01208369A (en) | 1989-08-22 |
| JPH0653609B2 true JPH0653609B2 (en) | 1994-07-20 |
Family
ID=12293228
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63030058A Expired - Lifetime JPH0653609B2 (en) | 1988-02-13 | 1988-02-13 | Manufacturing method of high toughness silicon nitride sintered body |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0653609B2 (en) |
-
1988
- 1988-02-13 JP JP63030058A patent/JPH0653609B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01208369A (en) | 1989-08-22 |
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