The effect of PH on nano powder silicon carbide properties synthesized by Sol-Gel method

SiC ceramics are important materials for coating and high-temperature structural applications [1]. Silicon carbide (SiC) powder is an excellent reinforcement for composites because of its high hardness, high strength, excellent resistance to oxidation and corrosion, low coefficient of thermal expansion, and high heating transfer capabilities[2,3]. On the other hand, SiC is a semi conducting material of great technological interest for devices designed to operate at high temperature, high powers, high frequency and harsh environments [3]. Silicon carbide is a promising material used in electronic devices that are particularly used at high temperatures. This is due to its high temperature electrical properties, high breakdown voltage, and high electron mobility. It is also used in various types of high temperature applications such as heating elements and refractory material for furnaces due to its high fracture strength, good thermal conductivity and relatively low coefficient of thermal expansion [4].Advanced ceramic materials based on SiC require extremely fine starting powders [3]. There are several common Synthesizing methods for ultra fine silicon carbide, including direct carbonization of Si metals, CVD from silane, sol–gel [5], thermal plasma [6], ball milling mixture Si and C [4] and carbothermal reduction of silicon dioxide [2]. These methods have their own advantages and disadvantages. For example, the silicon carbide powder made from chemical vapor deposition and sol–gel method has high purity and narrow particle size distribution. But the reactants are unstable and toxic and the production cost is high. Direct carbonization method is simple and cheap, but it will leave significant amounts of unreacted silicon and impurities. So far, the carbothermal reduction method is the most prevailing method for SiC powder synthesis [2].