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Common Preparation Methods of Silicon Nitride Powder

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Update time : 2021-09-22 14:49:12

What is silicon nitride?

Silicon nitride is an inorganic substance with the chemical formula Si3N4. It is an important structural ceramic material with high hardness, inherent lubricity, and wear resistance. It is an atomic crystal; it is resistant to oxidation at high temperatures. Moreover, it can resist the impact of cold and heat. It will not be broken if it is heated to above 1000°C in the air, cooled rapidly and then heated rapidly. It is precisely because of the excellent characteristics of silicon nitride ceramic that people often use it to manufacture mechanical components such as bearings, turbine blades, mechanical seal rings, permanent molds, and so on. If silicon nitride ceramics, which are resistant to high temperatures and difficult to transfer heat, are used to make the heating surfaces of engine components, not only can the quality of the engine be improved, fuel savings, and thermal efficiency can be improved. China, the United States, Japan and other countries have developed such engines.

Preparation method of silicon nitride

The direct nitridation of silicon powder is the earliest method used to prepare silicon nitride powder, and it is still widely used in China. The method is relatively simple and low in cost. The metal silicon powder is heated in an atmosphere of nitrogen or ammonia gas, and the metal silicon powder and the nitrogen source directly react to form silicon nitride powder.

This method has low cost and low equipment requirements. However, the nitridation reaction of metal silicon powder is an exothermic reaction. If the heat cannot be released in time during the nitriding process, it will cause the nearby metal silicon powder to melt and cause serious problems. The effect of nitriding reaction. Therefore, this process must strictly control the nitriding temperature, nitriding speed, the particle size of the raw materials, and the concentration of the diluent. The synthesized silicon nitride is in a non-uniform block shape. Therefore, it is also necessary to prepare silicon nitride powder by ball milling or other methods, which is not efficient, and it is easy to introduce impurities in the process.

Carbothermal reduction method is to reduce SiO2 powder with carbon under high temperature nitrogen environment. SiO2 is first reduced to gas phase SiO, and gas phase SiO reacts with nitrogen in the atmosphere to form silicon nitride.

Thermal decomposition method uses SiCl4 at low temperature to react with ammonia gas to obtain solid imino silicon (Si(NH2) or amino silicon (Si(NH2)4). These two silicides can be decomposed at high temperature to obtain nitride Silicon powder. This method has high reaction efficiency and can prepare a large amount of high-purity silicon nitride powder in a short time. The silicon nitride powder prepared by this method has uniform particle size and high purity, which is suitable for preparing high-quality nitride The process used for silicon powder. At present, this method has become the most important method used in the commercial production of high-purity and high-quality silicon nitride powder

Luoyang Trunnano Tech Co., Ltd (TRUNNANO) is a professional boride powder supplier with over 12 years experience in chemical products research and development. We accept payment via Credit Card, T/T, West Union and Paypal. Trunnano will ship the goods to customers overseas through FedEx, DHL, by air, or by sea.

If you are looking for high quality Si3N4 powder, please feel free to contact us and send an inquiry.

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