Silicon carbide, an inorganic substance with the chemical formula SiC, is smelted at high temperatures in resistance furnaces using raw materials such as quartz sand, petroleum coke (or coal coke), and wood chips (table salt is added to produce green silicon carbide). Silicon carbide is a semiconductor that exists in nature in the form of the extremely rare mineral moissanite. It has been mass-produced as powder and crystals since 1893, and is used as an abrasive and so on. Among the non-oxide high-tech refractory raw materials such as C, N and B, silicon carbide is one of the most widely and economically used, and can be referred to as golden steel sand or refractory sand. Chinese industrial production of silicon carbide is divided into two kinds of black silicon carbide and green silicon carbide, both are hexagonal crystals.

Introduction

Silicon carbide is commonly known as emery, and the name of gemstone is drill pith. It is a ceramic-like compound formed by bonding silicon and carbon. Silicon carbide exists in nature as a rare mineral such as moissanite. Silicon carbide powder has been widely used as abrasive since 1893. Sintering silicon carbide powder can produce hard ceramic-like silicon carbide particles, which can be used in materials that require high durability, such as automobile brake pads, clutches and bulletproof vests, in materials such as light-emitting diodes, early radio detectors, etc. It is also used in the manufacture of similar electronic devices. Silicon carbide is widely used today in the manufacture of high-temperature, high-voltage semiconductors.

Uses of silicon carbide

Silicon carbide products have special properties such as high temperature resistance, wear resistance, thermal shock resistance, chemical corrosion resistance, radiation resistance and good electrical and thermal conductivity, so they are widely used in various sectors of the national economy. In China, green silicon carbide is mainly used as abrasive. Black silicon carbide is used to make abrasive tools, mostly for cutting and grinding materials with low tensile strength, such as glass, ceramics, stone and refractories, etc. It is also used for grinding cast iron parts and non-ferrous metal materials. Abrasives made of green silicon carbide are mostly used for grinding hard alloys, titanium alloys, and optical glass. They are also used for honing of cylinder liners and fine grinding of high-speed steel tools. Cubic silicon carbide grinding tools are specially used for ultra-fine grinding of miniature bearings. Coating silicon carbide micropowder on the water turbine impeller by electroplating can greatly improve the wear resistance of the impeller; using mechanical pressure to press the cubic SiC200 grinding powder and W28 micropowder into the cylinder wall of the internal combustion engine can prolong the life of the cylinder by one time above. In the electrical industry, silicon carbide can be used as arrester valve body, silicon carbon heating element, far infrared generator, etc. In the electronics industry, if a large and complete silicon carbide single crystal is cultivated in an industrial silicon carbide furnace or by a special method on an industrial furnace, it can be used as a substrate for a light-emitting diode (such as a crystal lamp, a digital tube lamp); high-purity silicon carbide Crystal is a high-quality material for making radiation-resistant high-temperature semiconductors. Silicon carbide is one of the few semiconductor materials with a large band gap (2.86eV) and two conductivity types, P and n. In the aerospace industry, gas filters and combustion chamber nozzles made of silicon carbide have been used in rocket technology. The silicon carbide fiber, which has been industrially produced, is a new type of high-strength, high-modulus material with excellent heat resistance and oxidation resistance, and has good compatibility with metals and resins. The service temperature can reach 1200°C, and the strength retention rate at high temperature can reach more than 80%. It can be used to make heat shielding materials, high temperature resistant conveyor belts, filter cloths for filtering high temperature gases or molten metals, and can also be combined with carbon fibers or glass fibers as reinforcing materials for reinforcing metals and ceramics. Low-grade silicon carbide can be used as deoxidizer for steelmaking and additive for cast iron. In the carbon industry, silicon carbide is mainly used to produce bricks for ironmaking blast furnaces, such as graphite silicon carbide, silicon nitride bonded silicon carbide bricks, etc. In the production of graphite electrodes, silicon carbide is also used in the ingredients of coating refractory sintering materials for oxidation-resistant coating electrodes to increase the coating's ability to withstand rapid temperature changes. In the manufacture of special carbon materials - biochar, propane and trichloromethylsilane are often used as gas raw materials, and after high-temperature pyrolysis reaction, a silicon-containing pyrolytic carbon coating is deposited on the graphite substrate to increase the hardness of the product , strength and wear resistance. The silicon carbide in the coating exists in the crystal form of β-SiC, and the grain size is about 1 μm. Biochar products made by this method, such as silicon-containing pyrolytic carbon artificial heart valves, have good biocompatibility.