JPS5834426B2 - Manufacturing method of high-density silicon carbide sintered body - Google Patents

Description

【発明の詳細な説明】 この発明は反応焼結炭化けい素の製造法に関するもので
ある。DETAILED DESCRIPTION OF THE INVENTION This invention relates to a method for producing reactively sintered silicon carbide.

この方法はＳｉＣとＣの混合体を素原料として、これを
高温で焼成する過程でＳｉを注入して、成形体中の炭素
と反応せしめることにより、緻密な炭化けい素焼給体を
得る方法である。In this method, a mixture of SiC and C is used as the raw material, and during the process of firing it at high temperature, Si is injected and reacts with the carbon in the compact, thereby obtaining a dense silicon carbide fired body. be.

ＳｉＣは従来より耐火物や非金属発熱体として身近な材
料として用いられていたが、近年機械材料として研究が
活発に行なわれだしＳｉ３Ｎ４とともに次代を担う重要
なニューセラミックス材料として注目されている。SiC has traditionally been used as a familiar material for refractories and nonmetallic heating elements, but in recent years SiC has been actively researched as a mechanical material, and is attracting attention as an important new ceramic material for the next generation, along with Si3N4.

しかし機械材料として用いる場合気孔率の少ない高密度
の焼結体が必要である。However, when used as a mechanical material, a high-density sintered body with low porosity is required.

従来反応焼結ＳｉＣを製造する方法は、成形体を約７０
０°Ｃ〜９００’Ｃの温度にて仮焼し、その後金属けい
素粉末と接触させ約１６００℃の温度にてＳｉを溶融さ
せ仮焼体中の細孔を利用し毛細管現象により仮焼体中に
Ｓｉを注入し高温で反応焼結を行なっていた。The conventional method for producing reactive sintered SiC is to produce a compact of approximately 70%
Calcined at a temperature of 0°C to 900'C, then brought into contact with metal silicon powder and melted the Si at a temperature of about 1600°C to form a calcined body by capillary action using the pores in the calcined body. Si was injected into it and reaction sintering was performed at high temperature.

しかしこの方法だと気孔率の低い反応焼結ＳｉＣを製造
するには気孔率の低い仮焼体を用いる必要があり、この
ため仮焼体にＳｉを注入し反応焼結するのに長時間を要
し、しかも均一にＳｉを注入することが困難であった。However, with this method, it is necessary to use a calcined body with low porosity to produce reactively sintered SiC with low porosity, so it takes a long time to inject Si into the calcined body and perform reaction sintering. Moreover, it was difficult to uniformly implant Si.

この問題を解決するために約８００℃の仮焼時に仮焼結
体を一定時間酸素雰囲気に置き、仮焼体中の炭素を酸化
し、減少せしめることにより気孔を増したり同時にＳｉ
Ｃの表層部を一部酸化しＳｉＯ２とし、真空雰囲気高温
にてこのＳｉＯ２を飛散せしめ気孔率を増し、仮焼体に
よる溶融Ｓｉの注入を容易にする方法が用いられていた
。To solve this problem, the calcined body is placed in an oxygen atmosphere for a certain period of time during calcining at about 800°C, and the carbon in the calcined body is oxidized and reduced.
A method has been used in which a part of the surface layer of C is oxidized to form SiO2, and this SiO2 is scattered at high temperature in a vacuum atmosphere to increase the porosity and facilitate the injection of molten Si using a calcined body.

しかし上記の方法にて処理されたＳｉＣ焼結体は表層部
と内部の組成に差が生じており、安定した強度を必要と
する機械材料としては問題があった。However, the SiC sintered body treated by the above method has a difference in composition between the surface layer and the inside, which is problematic as a mechanical material that requires stable strength.

従ってこの方法で製造された焼結体は表層部を研削して
除く必要があった。Therefore, it was necessary to remove the surface layer of the sintered body produced by this method by grinding.

またこの方法では肉厚の薄い物では有効であるが肉厚の
厚い物では効果があまりみられないという欠点がある。Another disadvantage of this method is that it is effective for thin-walled objects, but not so effective for thick-walled objects.

本発明は以上の欠点を除去するために、仮焼体表面層の
炭素を減少させることなく、またＳｉＣ粒子の表層部を
酸化させることなくＳｉの注入速度を向上させたもので
あり、その要旨は炭化けい素粉末と炭素粉末との混合粉
末ｉｏｏ重量部に対し、セルロースを０．５重量部〜５
．０重量部添加混合した混合物を成型し、加熱処理を施
し、次いでこの成型体に溶融状態の金属けい素を含浸せ
しめた状態で１時間以上保持することを特徴とする高密
度炭化けい素焼給体の製造法である。In order to eliminate the above-mentioned drawbacks, the present invention improves the Si injection rate without reducing the carbon content in the surface layer of the calcined body and without oxidizing the surface layer of the SiC particles. is 0.5 parts by weight to 5 parts by weight of cellulose per ioo parts by weight of mixed powder of silicon carbide powder and carbon powder.
．． A high-density silicon carbide fired body characterized by molding a mixture in which 0 parts by weight has been added, subjecting it to heat treatment, and then holding the molded body impregnated with molten silicon metal for one hour or more. This is the manufacturing method.

即ちＳｉＣとＣとの混合成形品を製造するに際し、セル
ロースを均一に同時に混入するものである（この場合の
セルロースは結晶質セルロースの方がそれも出来る限り
微品質のものの方が好ましいものである）。That is, when manufacturing a mixed molded product of SiC and C, cellulose is mixed uniformly and at the same time (in this case, it is preferable that the cellulose is crystalline cellulose, and that it is of as fine a quality as possible). ).

次いで加熱処理（通常真空中５００℃〜ＳＯＯ℃）を施
し３０００〜１００ＯＯＡ（０，３〜１μ）の範囲の繊
維状マイクロポアーを規則正しく規制する。Next, heat treatment (usually at 500° C. to SOO° C. in vacuum) is performed to regularly regulate fibrous micropores in the range of 3000 to 100 OOA (0.3 to 1 μ).

この細孔を有する仮焼体は溶融Ｓｉを仮焼体内部まで注
入するのに極めて良好であり、従来の方法により製造さ
れた仮焼体に比較して、溶融Ｓｉの浸透速度は数倍以上
となり。This calcined body with pores is extremely good at injecting molten Si into the inside of the calcined body, and the permeation rate of molten Si is several times higher than that of calcined bodies manufactured by conventional methods. Next door.

肉厚で高密度のＳｉＣ焼結体を短時間で得ることができ
、しかもＳｉＣ焼結体の表層部と内部とでは材質的に均
一なものが得られ、従来の方法で製造されたＳｉＣ焼結
体の如く反応焼結後表層部を削除する必要がない。A thick, high-density SiC sintered body can be obtained in a short time, and the surface and interior of the SiC sintered body are uniform in material. Unlike solid bodies, there is no need to remove the surface layer after reaction sintering.

ＳｉＣ仮焼体内に繊維状マイクロポアーを生せしめるた
めに用いる微結晶セルロースは、木材、綿、麻など植物
の細肪膜の主成分であり、その構造は分子が比較的規則
正しく平行に配列している結晶領域のものがよく、特に
高純度の精製パルプより製造されたものがよい。Microcrystalline cellulose, which is used to create fibrous micropores in the SiC calcined body, is a main component of the fatty membranes of plants such as wood, cotton, and hemp, and its structure is composed of relatively regularly arranged parallel molecules. It is preferable to use a pulp in the crystalline region, especially one made from high-purity refined pulp.

これは仮焼後不純物の混入を防ぐためである。This is to prevent contamination of impurities after calcination.

また微結晶セルロースを添加させた場合マイクロポアー
を作り、Ｓｉの注入を容易にするばかりでなく、５ｉＣ
−Ｃ混合粉末を室温で加圧成形する際添加した微結晶セ
ルロースが容易に粒子の絡み合いを生じ粉体の成形性を
良好とし、複雑な形状の成形品をも製造できるという利
点がある。In addition, when microcrystalline cellulose is added, micropores are created, which not only facilitates the injection of Si but also improves 5iC
The microcrystalline cellulose added when press-molding the -C mixed powder at room temperature easily entangles the particles, improves the moldability of the powder, and has the advantage that molded products with complex shapes can be manufactured.

また高密度ＳｉＣ焼結体を製造する場合５ｉＣ−Ｃ圧粉
体はより高密度の圧粉体とする必要があるがその際本添
加物の効果は大きい。In addition, when producing a high-density SiC sintered body, the 5iC-C powder compact needs to be made into a high-density compact, and in this case, the effect of this additive is large.

なお溶融金属けい素を含浸せしめ反応焼結させた後、更
に熱間等方圧加圧焼結を行なうのはＳｉとＣの反応時間
の短縮の為であり、この熱間等方圧加圧焼結の温度は１
３００℃以上圧力は５００’９ ／ｃｒＡ以上が望、ま
しい。Note that after impregnating molten metal silicon and performing reaction sintering, hot isostatic pressure sintering is further performed in order to shorten the reaction time of Si and C. The sintering temperature is 1
The pressure at 300°C or higher is desirably 500'9/crA or higher.

反応焼結時間が０．５時間の焼結体はその焼結体を熱間
等方圧加圧焼結処理してもその効果はみられない。For a sintered body whose reaction sintering time is 0.5 hours, no effect is seen even if the sintered body is subjected to hot isostatic pressure sintering.

これは０．５時間の反応焼結において溶融ＳｉがＳｉＣ
仮焼体中に充分注入されていない為と思われる。This means that molten Si changes to SiC during reaction sintering for 0.5 hours.
This seems to be because it was not sufficiently injected into the calcined body.

また反応時間が最低の１時間の焼結体では、その焼結体
の物性値はあまり十分ではないが、この反応焼結体を更
に熱間等方圧加圧焼結する事により、密度の低下が若干
みられるものの硬さ、抗折力の向上がみられる。In addition, the physical properties of the sintered body whose reaction time is the minimum of 1 hour are not very sufficient, but by further hot isostatic pressure sintering of this reaction sintered body, the density can be improved. Although there is a slight decrease, hardness and transverse rupture strength are improved.

この理由として５ｉＣ−Ｃ−８ｉの未反応部が高温高圧
により、より反応の促進が行なわれるものと思われる。The reason for this is thought to be that the reaction of the unreacted portion of 5iC-C-8i is further promoted by the high temperature and high pressure.

以上述べて来た事実並びに後記する事実を導き出した実
験及びその結果を記する。The facts described above and the experiments that led to the facts to be described later and their results will be described below.

即ち、く実験 １〉 平均粒子径９μｍをもつα型炭化けい素粉末７０重量φ
とカーボンブラック３０重量袈を混合した粉末に微結晶
セルロースを表１の如く配合混合した粉末にワックスを
添加する。That is, Experiment 1> α-type silicon carbide powder 70 weight φ with an average particle size of 9 μm
Microcrystalline cellulose is mixed with a powder of 30 weight carbon black and 30 weight of carbon black as shown in Table 1. Wax is added to the powder.

これを１０００Ｋｑ／ｃｄの圧力で３０Ｘ１０Ｘ５−に
成形した後、真空中７００℃の温度にて仮焼する該仮焼
物の上に１（ｌの金属Ｓｉを載せ、０．１ ｔｏｒｒ
〜０．８ｔｏｒｒの減圧中で温度１５００℃まで１時間
で昇温し３時間保持して反応焼結した。This was formed into a 30X10X5- shape at a pressure of 1000Kq/cd, and then calcined at a temperature of 700°C in a vacuum.
Under reduced pressure of ~0.8 torr, the temperature was raised to 1500° C. over 1 hour and held for 3 hours to carry out reaction sintering.

焼結後の密度、硬さを同じく表１に示す。The density and hardness after sintering are also shown in Table 1.

く実験 ２〉 平均粒子径９μｍをもつα型炭化けい素粉床７０重量饅
とカーボンブラック３０重量φを混合した粉末と同じく
α−８ｉＣ粉末７０重量饅とカーボンブラック３０重量
饅混合した粉末１００重量部に対して微結晶セルロース
を１重量部添加した粉末にワックスを添加した混合粉末
を５００．※※１０００．２０００Ｋｇ／ｃｆ１１で３
０Ｘ１０Ｘ５ｍに加圧成形し、この圧粉体を７００℃に
て仮焼した後、この該仮焼物上に１０１の金属Ｓｉをの
せ０、１ ｔｏｒｒ −０，５ｔｏｒｒの減圧中で温度
１５００℃まで１時間で昇温し、３時間保持して反応焼
結した焼結後の密度、硬さ、抗折力を表２に示す。Experiment 2〉 A powder made by mixing 70 weight pieces of α-type silicon carbide powder with an average particle size of 9 μm and 30 weight pieces of carbon black, and a 100 weight piece of powder made by mixing 70 weight pieces of α-8iC powder and 30 weight pieces of carbon black. 500% of a mixed powder prepared by adding wax to a powder containing 1 part by weight of microcrystalline cellulose per 1 part by weight. ※※3 at 1000.2000Kg/cf11
After pressure molding to a size of 0 x 10 x 5 m and calcining this green compact at 700°C, 101 metal Si was placed on the calcined product and heated to a temperature of 1500°C under a reduced pressure of 0.1 torr - 0.5 torr. Table 2 shows the density, hardness, and transverse rupture strength after sintering, in which the temperature was raised for 3 hours and reaction sintered by holding for 3 hours.

く実験 ３〉 平均粒子径９μｍをもつα型炭化けい素粉末８０重量φ
とカーボンブラック２０重量φを混合した粉末に微結晶
セルロースを表３の如く配合混合した粉末にワックスを
添加し造粒する。Experiment 3〉 α-type silicon carbide powder with an average particle size of 9 μm 80 weight φ
Microcrystalline cellulose was mixed with a powder of 20 weight φ of carbon black as shown in Table 3, and wax was added to the mixed powder and granulated.

これを１ｏ ｏ ｏ Ｋｔｉ／ｃｙＡの圧力で３０×１
０×５１ｒＩｊＩｔに成形した後、真空中７００°Ｃの
温度にて仮焼する該仮焼物の上に１ｏｆｉの金属Ｓｉを
載せ０．１ｔｏｒｒ〜０．８ｔｏｒｒの減圧中で温度１
５００℃まで１時間で昇温し３時間保持して反応焼結し
た焼結後の密度、硬さを同じく表３に示す。This is 30×1 at a pressure of 1o o o Kti/cyA.
After molding to 0x51rIjIt, the calcined product is calcined at a temperature of 700°C in a vacuum. 1ofi of metal Si is placed on the calcined product and heated at a temperature of 1 in a reduced pressure of 0.1 torr to 0.8 torr.
Table 3 also shows the density and hardness after sintering, in which the temperature was raised to 500° C. for 1 hour and held for 3 hours for reaction sintering.

く実験 ４〉 平均粒子径９μｍをもつα型炭化けい素粉末とカーボン
ブラックを表４の如く配合し、このおのおの配合した混
合粉末に微結晶セルロースを更に１重量多添加した粉末
にワックスを添加し、この粉末を１０００ Ｋｙ／ｃｄ
で３０Ｘ１０Ｘ５ｍに加圧成形し、この圧粉体を７００
℃にて仮焼した。Experiment 4〉 α-type silicon carbide powder with an average particle size of 9 μm and carbon black were blended as shown in Table 4, and wax was added to the powder in which microcrystalline cellulose was added by 1 weight to each blended powder. , this powder at 1000 Ky/cd
Pressure molded to 30 x 10 x 5 m with
It was calcined at ℃.

その後該仮焼物上に１０１の金属Ｓｉをのせ０．１ｔｏ
ｒｒ −０，５ｔｏｒｒの減圧中で温度１５００’Ｃま
で１時間で昇温し３時間保持して反応焼結した焼結体の
密度、硬さ、抗折力を表４に示す。After that, 101 metal Si was placed on the calcined product and 0.1to
Table 4 shows the density, hardness, and transverse rupture strength of the sintered body, which was heated to 1500'C in 1 hour under a reduced pressure of rr -0.5 torr, held for 3 hours, and sintered by reaction.

く実験 ５〉 平均粒子径９μｍをもつα−８ｉＣ粉末７０重量多とカ
ーボンブラック３０重量饅を混合した粉末と更にこの粉
末（７０重量％ＳｉＣ＋３０重量％Ｃ）１００重量部に
対して微結晶セルロースを１重量部添加した粉末に各々
ワックスを添加し造粒した後、これを１ＯＯＯＫＩ！／
ｃｒＩｉの圧力で５０ｆ×５０藺に加圧成形し、真空中
７００°Ｃの温度にて仮焼する。Experiment 5> A powder obtained by mixing 70 parts by weight of α-8iC powder with an average particle size of 9 μm and 30 parts by weight of carbon black, and microcrystalline cellulose was added to 100 parts by weight of this powder (70% by weight SiC + 30% by weight C). Wax was added to each powder to which 1 part by weight had been added, and after granulation, this was mixed into 1OOOKI! /
It is pressure-molded to a size of 50 f x 50 m at a pressure of crIi and calcined at a temperature of 700°C in a vacuum.

該仮焼物に金属Ｓｉを十分接触させ０、１ ｔｏｒｒ
〜０．８ ｔｏｒｒの減圧中で温度１５００℃まで１時
間で昇温し３時間保持して反応焼結して、焼結後試料成
形体の中心内部と外周部の硬さを測定して、表５に結果
を示す。The calcined product is brought into sufficient contact with metal Si at a pressure of 0.1 torr.
In a reduced pressure of ~0.8 torr, the temperature was raised to 1,500°C in 1 hour, held for 3 hours, and subjected to reaction sintering. After sintering, the hardness of the inside center and outer periphery of the sample molded body was measured. Table 5 shows the results.

く実験 ６〉 平均粒子径９μｍをもつα型炭化けい素粉末７０重量φ
とカーボンブラック３０重量饅を混合した粉末１００重
量部に対して微結晶セルロースを０．５重量部添加し、
造粒し、これを１０００Ｋｇ／ ｃｄの圧力で３０Ｘ１
０Ｘ５７１１Ｊｌに成形した後、真空中７００℃の温度
にて仮焼した後、該仮焼物の上に１０ｒの金属Ｓｉを載
せ０．１ ｔｏｒｒ −０，６ｔｏｒｒの減圧中で温度
１５００℃まで１時間で昇温し、０．５，１，２，３．
４時間各々保持して反応焼結した。Experiment 6〉 α-type silicon carbide powder with an average particle size of 9 μm 70 weight φ
Adding 0.5 parts by weight of microcrystalline cellulose to 100 parts by weight of powder mixed with 30 parts by weight of carbon black,
Granulate it and 30X1 at a pressure of 1000Kg/cd.
After molding to 0X5711Jl, it was calcined in vacuum at a temperature of 700°C, and then 10r of metal Si was placed on the calcined product and heated to a temperature of 1500°C in a reduced pressure of 0.1 torr - 0.6 torr in 1 hour. Raise the temperature to 0.5, 1, 2, 3.
Each was held for 4 hours to carry out reaction sintering.

焼結後の密度、硬さ、曲げ強さを表６に示す。Table 6 shows the density, hardness, and bending strength after sintering.

次にこれらの焼結体を等方圧加圧焼結法により１３００
℃〜１４５０℃、圧力３００〜１ＯＯＯＫ９／ｃｒｌｉ
で各々１時間Ａｒガス圧力媒体を用いて処理した後、表
面を研削加工後の物性変化を同じく表６に示す。Next, these sintered bodies were sintered using an isostatic pressure sintering method.
℃~1450℃, pressure 300~1OOOK9/crli
Table 6 also shows the changes in physical properties after the surfaces were treated with Ar gas pressure medium for 1 hour and the surfaces were ground.

以上の実験結果より物性値（密度、抗折力、硬さ）の望
ましい製品が得られるのはセルロースの量が０．５〜５
．０重量部であり、又反応焼結時間は少なくとも１時間
は必要という事が判る。From the above experimental results, a product with desirable physical properties (density, transverse rupture strength, hardness) can be obtained when the amount of cellulose is 0.5 to 5.
．． 0 parts by weight, and it can be seen that the reaction sintering time is at least 1 hour.

そしてこの様な条件で得られた本件発明方法による製品
は中心部、外周部とも殆んど同一の優れた物性値を示し
、本材料が耐摩耗板、メカニカルシールリング、構造部
品材料として利用できるものであることがわかる。The product obtained by the method of the present invention obtained under these conditions exhibits excellent physical properties that are almost the same in both the center and the outer periphery, and this material can be used as wear-resistant plates, mechanical seal rings, and structural parts materials. I can see that it is something.

Claims (1)

【特許請求の範囲】 １ 炭化けい素粉末と炭素粉末との混合粉末ｉｏ。 重量部に対し、セルロースを０．５重量部〜５．０重量
部添加混合した混合物を成型し、加熱処理を施し、次い
でこの成型体に溶融状態の金属けい素を含浸せしめた状
態で１時間以上保持することを特徴とする高密度炭化け
い素焼給体の製造法。 ２ 炭化けい素粉末と炭素粉末との混合粉末ｉｏ。 重量部に対し、セルロースを０．５重量部〜５．０重量
部添加混合した混合物を成型し、加熱処理を施し、次い
でこの成型体に溶融状態の金属けい素を含浸せしめた状
態で１時間以上保持した後熱間等方圧加圧焼結をするこ
とを特徴とする高密度炭化けい素焼給体の製造法。[Claims] 1. Mixed powder io of silicon carbide powder and carbon powder. A mixture obtained by adding 0.5 parts by weight to 5.0 parts by weight of cellulose based on the weight part is molded, heat-treated, and then impregnated with molten metal silicon in this molded body for 1 hour. A method for producing a high-density silicon carbide combustion body characterized by retaining the above properties. 2 Mixed powder io of silicon carbide powder and carbon powder. A mixture obtained by adding 0.5 parts by weight to 5.0 parts by weight of cellulose based on the weight part is molded, heat-treated, and then impregnated with molten metal silicon in this molded body for 1 hour. A method for producing a high-density silicon carbide sintered body, which comprises performing hot isostatic pressure sintering after the above-mentioned holding.