【発明の詳細な説明】[Detailed description of the invention]
本発明は一酸化珪素発生原料組成物に関する。
近年メカニカルシール、軸受などの摺動材や電
子部品熱処理用治具材として炭化珪素−炭素複合
材料が広く用いられている。
炭素基材の表面をSiC化する方法としてはCVD
法やPVD法により炭素基材の表面にSiCを蒸着す
る方法及びSiや一酸化珪素（SiO）のガスを炭素
基材の表面と反応させて炭素基材をSiCに転化す
る方法が知られている。
上記中後者の方法の場合、SiOガスを得るため
には通常珪石粉及び金属珪素粉が用いられ、これ
らは高温でSiO2＋Si→2SiOのように反応する。
さらに珪石粉及び炭素粉を用いSiO2＋Ｃ→SiO＋
COの式によりSiOガスを発生する方法、また珪
石粉とSiC粉を使用し2SiO2＋SiC→3SiO＋COの
反応を利用する方法がある。
上記の各種SiOガス発生原料について反応式か
ら珪石粉と金属珪素粉を用いる原料の組合せが
COガスが発生しないことで最も効率がよいがこ
れらの原料が反応温度で溶融し、冷却後膨張して
上記原料を入れたケースが割れやすいこと、また
Si蒸気が出るために緑色の炭化珪素を生じた炭素
基材の表面に部分的に黒色の珪素が蒸着され色む
らを生じやすく商品価値が減ずる欠点がある。ま
た珪石粉とSiC粉を原料として用いた場合にも上
記反応の外にSiO2＋2SiC→3Si＋2COの反応も併
発し、Si蒸気が出るため同じ欠点を生ずる。
一方珪石粉と炭素粉を原料とした場合には珪石
粉が溶融しても炭素粉が溶融しないため全体とし
て焼結された状態になり原料ケースは破壊しな
い。しかしながら炭素粉は溶融しないので内部が
有効に反応せずこのため上記反応式のモル比以上
の炭素粉の添加が必要であり、このため発生した
SiOガスが原料中の炭素粉と反応しSiCとなり
SiOガスの発生効率が低下する欠点がある。この
ようにSiOガスの発生効率が悪いと発生効率のよ
い原料にくらべて炭素基材表面におけるSiC層を
厚くできないことになり、したがつて同じ厚さに
するには多量の原料を必要とし不経済となる。そ
こで発明者は珪石粉と炭素粉からなる原料につ
き、さらに研究を重ねた結果、炭素粉の代りに有
機材料を使用するとSiOガスの発生効率が良くな
ることを見出した。
本発明は、珪石粉に有機材料を液状にして、該
有機材料の炭化後にSiO2／Ｃのモル比が0.5〜1.2
となるような量で混合してなる一酸化珪素発生原
料組成物に関する。
本発明において有機材料とは熱処理によつて炭
化し得る有機物のことであり、タールピツチ、コ
ールタール、フエノール樹脂のような炭化率の大
きいものが好ましい。有機材料を珪石粉と混合す
る場合、有機材料がコールタールのような常温で
液体の場合にはそのまま又は溶媒を加え、ノボラ
ツクフエノール樹脂粉末、タールピツチ等の固体
の場合は溶媒に溶かすか又は加熱溶融して液状に
して珪石粉と混合する。さらに必要によつては造
粒、成形、炭化などの前処理を行なう。
珪石粉と混合する有機材料の量は、有機材料の
炭化後におけるSiO2／Ｃのモル比が0.5〜1.2とな
るように有機材料の炭化率により決定する。前記
SiO2／Ｃのモル比が0.5未満では発生したSiOが
過剰の炭素により原料中でSiO＋2C→SiC＋COの
反応によつて消費されてSiOの量が減少する。
SiO2／Ｃのモル比が1.2を越えると炭素量が減少
するから珪石粉の溶融によつてSiOガスの発生効
率が低下する。SiO2／Ｃのモル比は0.8〜1.0が好
ましい範囲である。
以下実施例を説明する。
実施例 １
粒径100メツシユ以下の珪石粉1000gにフエノ
ール樹脂（炭化率50％）400gをアセトン400gに
溶かした溶液を加えて（モル比1.0）混合し、乾
燥後外径100mm、高さ100mmに成形し1000℃まで５
時間かけて炭化し1200gのSiO発生原料をえた。
実施例 ２
粒径100メツシユ以下の珪石粉1000gにコール
タールピツチ（炭化率54％）370gを加え（モル
比1.0）150℃で混合後粉砕し実施例１と同様に成
形、炭化し1200gのSiO発生原料をえた。
比較例
粒径100メツシユ以下の珪石粉1000gと粒径100
メツシユ以下のコークス粉200gを混合し（モル
比1.0）SiO発生原料とした。
以上の実施例、比較例でえた原料を内径100mm
内高さ400mmの黒鉛製容器の下部に置き、上部に
カサ密度1.70g／cm3の黒鉛材料を設置し、2000℃
で２時間反応させて炭化珪素―炭素複合材料をえ
た。結果は第１表に示すごとくである。
The present invention relates to a silicon monoxide generating raw material composition. In recent years, silicon carbide-carbon composite materials have been widely used as sliding materials for mechanical seals and bearings, and as jig materials for heat treatment of electronic components. CVD is a method to convert the surface of carbon base material to SiC
There are two known methods: depositing SiC on the surface of a carbon substrate using a method or PVD method, and converting the carbon substrate into SiC by reacting Si or silicon monoxide (SiO) gas with the surface of the carbon substrate. There is. In the case of the latter method, silica powder and metal silicon powder are usually used to obtain SiO gas, and these react at high temperatures as SiO 2 +Si→2SiO.
Furthermore, using silica powder and carbon powder, SiO 2 +C→SiO+
There is a method of generating SiO gas using the CO formula, and a method of using silica powder and SiC powder and utilizing the reaction of 2SiO 2 +SiC→3SiO+CO. Regarding the various SiO gas generating raw materials mentioned above, the combination of raw materials using silica stone powder and metal silicon powder is determined from the reaction formula.
It is most efficient because no CO gas is generated, but these raw materials melt at the reaction temperature and expand after cooling, making the case containing the raw materials easy to break.
Due to the release of Si vapor, black silicon is partially deposited on the surface of the carbon substrate that has produced green silicon carbide, which tends to cause color unevenness and reduce commercial value. Furthermore, when silica powder and SiC powder are used as raw materials, in addition to the above reaction, the reaction of SiO 2 +2SiC→3Si+2CO also occurs, producing Si vapor, resulting in the same drawback. On the other hand, when silica powder and carbon powder are used as raw materials, even if the silica powder is melted, the carbon powder is not melted, so that the entire case is sintered and the raw material case is not destroyed. However, since the carbon powder does not melt, the internal reaction does not occur effectively. Therefore, it is necessary to add more carbon powder than the molar ratio in the above reaction formula, and as a result,
SiO gas reacts with carbon powder in the raw material and becomes SiC.
There is a drawback that the efficiency of SiO gas generation decreases. In this way, if the generation efficiency of SiO gas is low, the SiC layer on the surface of the carbon substrate cannot be made thicker than a raw material with a high generation efficiency, and therefore a large amount of raw material is required to achieve the same thickness. It becomes the economy. As a result of further research into raw materials consisting of silica powder and carbon powder, the inventor discovered that the efficiency of SiO gas generation can be improved by using an organic material in place of the carbon powder. In the present invention, an organic material is liquefied in silica powder, and after carbonization of the organic material, the molar ratio of SiO 2 /C is 0.5 to 1.2.
It relates to a silicon monoxide generating raw material composition which is mixed in an amount such that the following is obtained. In the present invention, the organic material refers to an organic material that can be carbonized by heat treatment, and materials with a high carbonization rate such as tar pitch, coal tar, and phenolic resin are preferred. When mixing an organic material with silica powder, if the organic material is a liquid at room temperature such as coal tar, it may be mixed as is or a solvent may be added; if it is a solid such as novolac phenol resin powder or tar pitch, it may be dissolved in a solvent or heated. It is melted into a liquid state and mixed with silica powder. Further, if necessary, pretreatments such as granulation, molding, and carbonization are performed. The amount of the organic material to be mixed with the silica powder is determined by the carbonization rate of the organic material so that the molar ratio of SiO 2 /C after carbonization of the organic material is 0.5 to 1.2. Said
When the molar ratio of SiO 2 /C is less than 0.5, the generated SiO is consumed by the reaction of SiO+2C→SiC+CO in the raw material due to excess carbon, and the amount of SiO decreases.
If the molar ratio of SiO 2 /C exceeds 1.2, the amount of carbon decreases and the efficiency of generating SiO gas decreases due to melting of the silica powder. The molar ratio of SiO 2 /C is preferably in the range of 0.8 to 1.0. Examples will be described below. Example 1 A solution of 400 g of phenol resin (carbonization rate 50%) dissolved in 400 g of acetone was added to 1000 g of silica powder with a particle size of 100 mesh or less (molar ratio 1.0), and after drying, it was made into an outer diameter of 100 mm and a height of 100 mm. Molded and heated to 1000℃ 5
It took a long time to carbonize and yielded 1200g of SiO generating raw material. Example 2 370 g of coal tar pitch (carbonization rate 54%) was added to 1000 g of silica powder with a particle size of 100 mesh or less (molar ratio 1.0), mixed at 150°C, crushed, molded and carbonized in the same manner as in Example 1, and 1200 g of SiO I got the generated raw materials. Comparative example: 1000g of silica powder with a particle size of 100 mesh or less and a particle size of 100
200g of coke powder of less than mesh size was mixed (mole ratio 1.0) to serve as a raw material for SiO generation. The raw materials obtained in the above examples and comparative examples were used with an inner diameter of 100 mm.
It was placed at the bottom of a graphite container with an internal height of 400 mm, a graphite material with a bulk density of 1.70 g/cm 3 was placed on the top, and it was heated to 2000℃.
The mixture was reacted for 2 hours to obtain a silicon carbide-carbon composite material. The results are shown in Table 1.
【表】
第１表より明らかなごとく本発明の場合従来法
と比較してSiOガス発生効率が向上し同量の原料
でSiC層の厚さを約1.7倍厚くすることができる。
このように本発明によると従来SiOガス発生効
率の低かつた珪石粉と炭素粉からなる原料におけ
る炭素粉の代りに有機材料を用いることにより
SiOガス発生効率を上げ、同量の原料で炭化珪素
―炭素複合材料のSiC層の厚さを厚くすることが
できるばかりでなく、通常使用される珪石粉と金
属珪素粉よりなる原料の場合における原料ケース
の破壊や珪素の蒸着が起こりやすいという欠点を
なくすことができるなどの効果がある。[Table] As is clear from Table 1, in the case of the present invention, the SiO gas generation efficiency is improved compared to the conventional method, and the thickness of the SiC layer can be made approximately 1.7 times thicker with the same amount of raw material. As described above, according to the present invention, by using an organic material in place of carbon powder in the conventional raw materials consisting of silica powder and carbon powder, which have low SiO gas generation efficiency,
Not only can the efficiency of SiO gas generation be increased and the thickness of the SiC layer of silicon carbide-carbon composite materials can be increased with the same amount of raw materials, but also the There are effects such as being able to eliminate the disadvantages of easy destruction of the raw material case and silicon vapor deposition.