JPH054946B2 - - Google Patents
Info
- Publication number
- JPH054946B2 JPH054946B2 JP60001852A JP185285A JPH054946B2 JP H054946 B2 JPH054946 B2 JP H054946B2 JP 60001852 A JP60001852 A JP 60001852A JP 185285 A JP185285 A JP 185285A JP H054946 B2 JPH054946 B2 JP H054946B2
- Authority
- JP
- Japan
- Prior art keywords
- sintering
- sic
- atmosphere
- torr
- temperature
- 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 - Lifetime
Links
- 238000005245 sintering Methods 0.000 claims description 22
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 17
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 10
- 238000010438 heat treatment Methods 0.000 claims description 10
- 229910052799 carbon Inorganic materials 0.000 claims description 9
- 238000000034 method Methods 0.000 claims description 9
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 6
- 229910052796 boron Inorganic materials 0.000 claims description 6
- 229910010271 silicon carbide Inorganic materials 0.000 description 17
- 239000007789 gas Substances 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 8
- 229910021431 alpha silicon carbide Inorganic materials 0.000 description 5
- 239000000843 powder Substances 0.000 description 5
- 239000002245 particle Substances 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 239000002344 surface layer Substances 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- -1 and at the same time Chemical compound 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 229910003460 diamond Inorganic materials 0.000 description 1
- 239000010432 diamond Substances 0.000 description 1
- 239000002612 dispersion medium Substances 0.000 description 1
- 238000010494 dissociation reaction Methods 0.000 description 1
- 230000005593 dissociations Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process 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
- 230000003993 interaction Effects 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 238000000462 isostatic pressing Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 239000011812 mixed powder Substances 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 238000013001 point bending Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Landscapes
- Ceramic Products (AREA)
Description
【発明の詳細な説明】
産業上の利用分野
この発明は炭化ケイ素粉末からなる成形体を焼
結するための方法に関するものである。DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method for sintering a molded body made of silicon carbide powder.
従来の技術
炭化ケイ素SiCは、耐熱性に優れかつ高い硬度
を有しているので、エンジン部品やタービン部品
などの高温構造材料としての用途が期待されてい
るが、難焼結性であるために、ホウ素Ｂや炭素Ｃ
を含む焼結助剤を添加して成形体の焼結を行なつ
ている。これらの添加物は高温での安定性が高い
ので、2000℃以上の高温での焼成が可能であり、
このような高温で焼成することにより常圧でも緻
密な焼結体を得ることができる。Conventional technology Silicon carbide (SiC) has excellent heat resistance and high hardness, so it is expected to be used as a high-temperature structural material for engine parts and turbine parts, but it is difficult to sinter. , boron B and carbon C
The molded body is sintered by adding a sintering aid containing. These additives have high stability at high temperatures, so they can be fired at high temperatures of 2000℃ or higher.
By firing at such a high temperature, a dense sintered body can be obtained even at normal pressure.
ところで焼結品の強度や寸法精度などの特性
は、原料特性のみならず焼成条件にも大きく依存
しているが、従来では昇温過程および焼結温度で
の保温過程における雰囲気を一律にヘリウム
（He）あるいはアルゴン（Ar）などの希ガスの
常圧（１気圧）もしくは減圧雰囲気としている。 By the way, the properties such as strength and dimensional accuracy of sintered products depend not only on the raw material properties but also on the firing conditions, but in the past, the atmosphere during the temperature raising process and the heat retention process at the sintering temperature was uniformly changed to helium ( The atmosphere is a normal pressure (1 atm) or reduced pressure atmosphere of a rare gas such as He (He) or argon (Ar).
発明が解決しようとする問題点
しかるにSiCや焼結助剤の挙動は、昇温速度や
圧力などの雰囲気に大きく影響されるにも拘わら
ず、従来では、昇温過程および焼結温度での保温
過程における温度と雰囲気との相互関係に特に配
慮することなく、一律に常圧もしくは減圧した希
ガス雰囲気としていたため、焼結体の強度が必ず
しも充分には高くならず、また強度にばらつきが
生じる問題があつた。Problems to be Solved by the Invention However, although the behavior of SiC and sintering aids is greatly influenced by the atmosphere, such as the rate of temperature rise and pressure, conventional techniques Because the atmosphere was uniformly kept at normal pressure or a rare gas atmosphere at reduced pressure without paying particular attention to the interaction between temperature and atmosphere during the process, the strength of the sintered body was not necessarily high enough, and the strength also varied. There was a problem.
この発明上記の事情に鑑み、高強度のSiC焼結
体を安定して得ることのできる焼結方法を提供す
ることを目的とするものである。 SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a sintering method that can stably obtain a high-strength SiC sintered body.
問題点を解決するための手段
この発明は、上記の目的を達成するために、炭
化ケイ素粉末成形体を焼結するにあたり、室温か
ら1400℃までの加熱過程では10-2Torr以下の減
圧雰囲気とし、また1400℃から1900℃までの加熱
過程では20〜200TorrのHeガス雰囲気とし、さ
らに1900℃以上の温度では、200〜500TorrのHe
ガス雰囲気とすることを特徴とするものである。Means for Solving the Problems In order to achieve the above object, the present invention provides a reduced pressure atmosphere of 10 -2 Torr or less during the heating process from room temperature to 1400°C when sintering a silicon carbide powder compact. In addition, during the heating process from 1400℃ to 1900℃, a He gas atmosphere of 20 to 200 Torr is used, and at a temperature of 1900℃ or higher, a He gas atmosphere of 200 to 500 Torr is used.
It is characterized by a gas atmosphere.
この発明において室温から1400℃までの加熱過
程で10-2Torr以下の減圧雰囲気とするのは、つ
ぎの理由からである。すなわちSiC粒子の表面に
は不可避的に酸素が存在し、強度低下の原因にな
るので、これを炭素と反応させて一酸化炭素とし
て除去し、併せて焼結助剤であるホウ素および炭
素もしくはこれらを含む蒸気をSiC粒子の表面に
積極的に移行させるためである。また1400℃から
1900℃までの加熱過程で10〜200TorrのHeガス
雰囲気とするのは、SiC粒子の表面に移行したホ
ウ素および炭素をSiC粒子の表面に固定するとと
もに、Heガスによつて微小気孔内の熱伝達を増
加させ、焼結体の内外の温度差を僅少化するため
である。さらに1900℃以上の温度すなわち1900℃
から焼結温度（α−SiCでは2020℃、β−SiCで
は2090℃）までにおいて200〜500TorrのHeガス
雰囲気とするのは、Heによる気孔の微小化を促
進するとともに、圧力を500Torr以上とした場合
には焼結体の強度低下が生じ、200Torr以下とし
た場合には、SiCのSiとＣとへの解離が進行して
焼結体の表面層に黒鉛が生成し、強度が低下して
しまうからである。 The reason why a reduced pressure atmosphere of 10 −2 Torr or less is used in the heating process from room temperature to 1400° C. in this invention is as follows. In other words, since oxygen inevitably exists on the surface of SiC particles and causes a decrease in strength, this is removed by reacting with carbon as carbon monoxide, and at the same time, boron and carbon, which are sintering aids, and carbon or these are removed. This is to actively transfer the vapor containing the ions to the surface of the SiC particles. Also from 1400℃
The purpose of creating a He gas atmosphere of 10 to 200 Torr during the heating process to 1900℃ is to fix the boron and carbon that have migrated to the surface of the SiC particles, and to promote heat transfer within the micropores by the He gas. This is to increase the temperature difference between the inside and outside of the sintered body and minimize the temperature difference between the inside and outside of the sintered body. Furthermore, the temperature above 1900℃ i.e. 1900℃
to sintering temperature (2020°C for α-SiC, 2090°C for β-SiC), a He gas atmosphere of 200 to 500 Torr promotes miniaturization of pores due to He, and the pressure is set to 500 Torr or higher. If the temperature is lower than 200 Torr, the dissociation of SiC into Si and C will progress and graphite will form on the surface layer of the sintered body, resulting in a decrease in strength. This is because it will be put away.
実施例
以下にこの発明の実施例を比較例と併せて記
す。なお、実施例および比較例のいずれの場合に
おいても、つぎに述べる方法で作成したSiC粉末
成形体を用いて焼結を行なつた。Examples Examples of the present invention will be described below together with comparative examples. In both Examples and Comparative Examples, sintering was performed using SiC powder compacts prepared by the method described below.
原料であるSiC粉末は、β−SiC（イビデン(株)
製、商品名；ウルトラフアイン）およびα−SiC
（昭和電工(株)製、商品名；Ａ−１）を用いた。ま
た焼結助剤である炭素は、カーボンブラツク（三
菱化成工業(株)製、商品名；ダイヤブラツクＩ）を
用い、またホウ素は非晶質素（シユタルク社製）
を用いた。SiC粉末98wt％、炭素1wt％、ホウ素
1wt％をメチルアルコールを分散媒としてボール
ミルで96時間攪拌混合し、その混合粉を60℃で乾
燥した後、50〜100μm程度の粒径に造粒し、これ
を金型に入れて加圧することにより、直径30mm、
長さ60mmの形状に１次成形し、さらに静水圧加圧
により３トン／cm2の圧力で２次成形を行ない、試
料とするSiC粉末成形体を得た。 The raw material SiC powder is β-SiC (Ibiden Co., Ltd.)
(Product name: Ultra Fine) and α-SiC
(manufactured by Showa Denko Co., Ltd., trade name: A-1) was used. Carbon, which is a sintering aid, is carbon black (manufactured by Mitsubishi Chemical Industries, Ltd., trade name: Diamond Black I), and boron is an amorphous element (manufactured by Schüttarch).
was used. SiC powder 98wt%, carbon 1wt%, boron
1wt% is stirred and mixed in a ball mill for 96 hours using methyl alcohol as a dispersion medium, and after drying the mixed powder at 60℃, it is granulated to a particle size of about 50 to 100μm, and this is placed in a mold and pressurized. 30mm in diameter,
It was first formed into a shape with a length of 60 mm, and then subjected to secondary forming by isostatic pressing at a pressure of 3 tons/cm 2 to obtain a sample SiC powder compact.
実施例
上述した成形体を、室温から1400℃までは10-2
Torr以下の減圧雰囲気とし、1400℃から1900℃
までは10〜200TorrのHeガス雰囲気とし、さら
に1900℃から焼結温度（α−SiCについては2020
℃、β−SiCについては2090℃）までは、100〜
760Torrの範囲で階段的に圧力を変えたHeガス
雰囲気とし、かつ焼結温度に40分間保持すること
により焼結を行なつた。Example The above-mentioned molded body was heated at 10 -2 from room temperature to 1400℃.
Reduced pressure atmosphere below Torr, 1400℃ to 1900℃
Up to 10 to 200 Torr He gas atmosphere, and then sintering temperature from 1900℃ (2020 for α-SiC)
℃, 2090℃ for β-SiC), 100~
Sintering was performed by creating a He gas atmosphere in which the pressure was varied stepwise in the range of 760 Torr, and maintaining the sintering temperature for 40 minutes.
得られた焼結体の特性を調べるために３×４×
30（mm）の大きさに成形し、強度（三点曲げによ
る抗折強度、以下同じ）を測定した。20本の平均
値を求めたところ、第１図に示す結果を得た。な
お、第１図中○印はβ−SiCを主原料とするもの
についての結果であり、□印はα−SiCを主原料
とするものについての結果である。第１図から明
らかなように、焼結温度でのHeガスの圧力を200
〜500Torrとすることにより、ガスタービンエン
ジン部品として要求される60Kg／mm2以上の強度と
することができた。 In order to investigate the characteristics of the obtained sintered body, 3×4×
It was molded into a size of 30 (mm) and its strength (flexural strength by three-point bending, the same applies hereinafter) was measured. When the average value of 20 pieces was calculated, the results shown in Figure 1 were obtained. In FIG. 1, the ○ marks are the results for those whose main raw material is β-SiC, and the □ marks are the results for those whose main raw material is α-SiC. As is clear from Figure 1, the pressure of He gas at the sintering temperature is 200
By setting the strength to ~500 Torr, it was possible to achieve a strength of 60 Kg/mm 2 or higher, which is required for gas turbine engine parts.
比較例
前述した成形体を、Heガス１気圧の雰囲気で
室温から焼結温度（α−SiCについては2020℃、
β−SiCについては2090℃）まで加熱昇温するこ
とにより焼成した。Comparative example The above-mentioned compact was sintered in an atmosphere of 1 atmosphere of He gas at a temperature ranging from room temperature to 2020℃ for α-SiC,
β-SiC was fired by heating to 2090°C.
得られた焼結体についての強度を調べたところ
第１図に示す760Torrでの強度より６〜12％程度
低い値となつた。 When the strength of the obtained sintered body was examined, it was found to be about 6 to 12% lower than the strength at 760 Torr shown in FIG.
比較例
前述した成形体を、10-2〜10-3Torrの減圧雰
囲気で室温から焼結温度まで加熱昇温することに
より焼成した。Comparative Example The above-described molded body was fired by heating and increasing the temperature from room temperature to the sintering temperature in a reduced pressure atmosphere of 10 -2 to 10 -3 Torr.
得られた焼結体を調べたところ、表層部に黒鉛
が生成し、かつSiとしての実質厚さが現象してお
り、Siの解難が生じていたことが認められた。ま
た強度は上記の比較例の場合と同様に低い値と
なつていた。 When the obtained sintered body was examined, it was found that graphite was generated on the surface layer and the actual thickness of Si was reduced, indicating that the Si was difficult to solve. Moreover, the strength was a low value as in the case of the above-mentioned comparative example.
比較例
室温から1400℃までの加熱過程では10-210-4
Torrの減圧雰囲気とし、それ以降は１気圧のHe
ガス雰囲気として前述の成形体の焼成を行なつ
た。Comparative example: 10 -2 10 -4 during heating process from room temperature to 1400℃
The atmosphere is reduced to Torr, and after that, the atmosphere is He at 1 atm.
The above molded body was fired in a gas atmosphere.
得られた焼結体の強度は、前記の比較例にお
ける場合と同様に低い値となつていた。 The strength of the obtained sintered body was as low as in the comparative example.
これらの実施例および比較例の結果から、この
発明の方法によれば、高強度のSiC粉末焼結体を
得られることが認められた。 From the results of these Examples and Comparative Examples, it was confirmed that a high-strength SiC powder sintered body could be obtained by the method of the present invention.
発明の効果
以上の説明から明らかなようにこの発明の焼結
方法によれば、加熱昇温過程での各温度に応じた
雰囲気とすることにより、焼結助剤の移行促進お
よび気孔の微小化の促進を図ることができるうえ
に、原子の移動度を増進させることができ、その
結果、実用に供し得る充分高強度のSiC焼結部品
を安定して得ることができる。Effects of the Invention As is clear from the above explanation, according to the sintering method of the present invention, by creating an atmosphere that corresponds to each temperature during the heating process, the migration of the sintering aid is promoted and the pores are miniaturized. In addition, it is possible to promote the mobility of atoms, and as a result, it is possible to stably obtain SiC sintered parts with sufficiently high strength for practical use.
第１図は焼結温度におけるHeガスの圧力と強
度との関係を示す線図である。
FIG. 1 is a diagram showing the relationship between He gas pressure and strength at sintering temperatures.
Claims (1)
炭化ケイ素粉末成形体を焼結するにあたり、室温
から1400℃までの加熱過程では、10-2Torr以下
の減圧雰囲気とし、1400℃から1900℃までの加熱
過程では、20〜200TorrのHeガス雰囲気とし、
さらに1900℃から焼結温度までは200〜500Torr
のHeガス雰囲気とすることを特徴とする炭化ケ
イ素粉末成形体の焼結方法。1. When sintering a silicon carbide powder compact to which a sintering aid containing boron and carbon has been added, a reduced pressure atmosphere of 10 -2 Torr or less is used during the heating process from room temperature to 1400°C, and from 1400°C to 1900°C. In the heating process, a He gas atmosphere of 20 to 200 Torr is used.
Furthermore, from 1900℃ to sintering temperature is 200~500Torr.
A method for sintering a silicon carbide powder compact, characterized by using a He gas atmosphere.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60001852A JPS61163167A (en) | 1985-01-09 | 1985-01-09 | Manufacture of silicon carbide powder molded body |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60001852A JPS61163167A (en) | 1985-01-09 | 1985-01-09 | Manufacture of silicon carbide powder molded body |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61163167A JPS61163167A (en) | 1986-07-23 |
| JPH054946B2 true JPH054946B2 (en) | 1993-01-21 |
Family
ID=11513076
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60001852A Granted JPS61163167A (en) | 1985-01-09 | 1985-01-09 | Manufacture of silicon carbide powder molded body |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61163167A (en) |
-
1985
- 1985-01-09 JP JP60001852A patent/JPS61163167A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61163167A (en) | 1986-07-23 |
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