by hearingearly hearingearly

Silicon carbide powder: So far, it has been proposed to combine a silicon source that is liquid at normal temperature (specifically, ethyl silicate), a carbon source that is liquid at normal temperature (specifically, phenolic resin), and a carbon source capable of dissolving carbon. A method of producing high-purity silicon carbide powder by mixing a source catalyst (specifically, maleic acid). Specifically, silicon carbide powder is produced by heating a mixture containing a silicon source, a carbon source, and a catalyst (for example, Patent Document 1).

When maleic acid is used as the catalyst, the sulfur content contained in the silicon carbide powder is lower than when toluenesulfonic acid is used as the catalyst. Therefore, the use of maleic acid as a catalyst ensures the production of silicon carbide powder suitable for use in the semiconductor field where sulfur is an impurity.

In addition, in order to produce silicon carbide powder with an average particle diameter of 100 to 200 μm, a technique of heating a mixture containing a silicon source, a carbon source, and a catalyst in two stages has also been proposed. Furthermore, it is also known that when the ratio between carbon contained in the carbon source and silicon contained in the silicon source (hereinafter, C/Si) is greater than 2.0 and less than 2.5, the amount of free carbon can be reduced.

As a result of in-depth research on silicon carbide powder, it has been found that there are many differences between the silicon source, the carbon source, and the catalyst from the three viewpoints of the reactivity between carbon and silicon, the amount of free carbon (FC), and the yield of silicon carbide powder. The optimal ranges of the three parameters of silicon source content, carbon source content and catalyst content in the mixture. https://hearingearly.com/silicon-carbide-powder/

Therefore, the silicon carbide powder can exhibit good results from the viewpoints of the reactivity between carbon and silicon, the amount of free carbon (FC), and the yield of the silicon carbide powder. According to the characteristics of the silicon carbide powder, in the mixture containing the silicon source, the carbon source and the catalyst, the silicon source is methyl silicate, and when the silicon carbide powder mixture is expressed by 100% by weight, the weight percentage of the carbon source is 33 The weight percentage of the silicon source is 55 weight % or more and 62 weight % or less, and the catalyst weight percentage is 3 weight % or more and 10 weight % or less.

When the silicon carbide powder mixture is expressed by 100% by weight, the weight percentage of the carbon source is 34.5% by weight or more and 38% by weight or less.

When the silicon carbide powder mixture is expressed by 100% by weight, the weight percentage of the silicon source is 57% by weight or more and 61% by weight or less.

When the silicon carbide powder mixture is expressed by 100% by weight, the weight percentage of the catalyst is 3% by weight or more and 8% by weight or less.

Actual effect:

Silicon carbide powder can exhibit good results from the viewpoints of reactivity between carbon and silicon, the amount of free carbon (FC), and the yield of silicon carbide powder.

In the silicon carbide powder according to this embodiment, in the mixture consisting of the silicon source, the carbon source and the catalyst, the silicon source is methyl silicate. When the mixture is expressed by 100% by weight, the weight percentage of the carbon source is 33% by weight or more and 39% by weight or less, the weight% of the silicon source is 55% by weight or more and 62% by weight or less, and the weight% of the catalyst is 3% by weight More than 10% by weight.

In this embodiment, because the three parameters of silicon carbide powder silicon source content, carbon source content and catalyst content are optimized in the mixture of silicon source, carbon source and catalyst, the reactivity between carbon and silicon, From the viewpoint of the amount of free carbon and the rate of silicon carbide powder, silicon carbide powder is good. The mixing process of silicon carbide powder is to mix a silicon source that is liquid at normal temperature, a carbon source that is liquid at normal temperature, and a catalyst (polymerization catalyst or cross-linking catalyst) that can dissolve the carbon source to form a mixture containing silicon source and carbon source. and catalyst mixture.

Examples of silicon sources for silicon carbide powder include methyl silicate (ie, tetramethoxysilane). As the silicon source, a monomer of methyl silicate may be used, or a polymer of methyl silicate (for example, a low molecular weight polymer (oligomer) of methyl silicate) may be used. Here, the term oligomer refers to a polymer with a degree of polymerization of approximately 2 to 15. As the methyl silicate, it is preferable to use one having a purity determined according to the use of the silicon carbide powder. When using high-purity methyl silicate, the initial impurity content of methyl silicate is preferably 20 ppm or less.