Method for preparing silicon nitride

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 effects of cold and heat. If it is heated to above 1000°C in the air, cooled quickly, and then heated quickly, it will not break. It is precisely because of the excellent characteristics of silicon nitride ceramics that people often use it to manufacture mechanical parts such as bearings, turbine blades, mechanical seal rings, permanent molds and so on. If the heating surface of the engine components is made of high temperature resistant silicon nitride ceramics that is not easy to transfer heat, it can not only improve the quality of the engine, save fuel, and improve thermal efficiency. China, the United States, Japan and other countries have all developed such engines.

Method for preparing silicon nitride

Direct nitridation of silicon powder is the earliest method used to prepare silicon nitride powder, and it is still widely used in China. This method is relatively simple and low in cost. The metal silicon powder is heated in a nitrogen or ammonia atmosphere, and the metal silicon powder reacts directly with the nitrogen source to generate 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, causing serious problems. The influence of nitridation reaction. Therefore, this process must strictly control the nitriding temperature, nitriding speed, raw material particle size, diluent concentration, etc. The synthesized silicon nitride is in the shape of uneven lumps. Therefore, it is also necessary to prepare silicon nitride powder by ball milling or other methods, which is not efficient and easily introduces impurities in the process.

The carbothermic reduction method uses carbon to reduce SiO2 powder in a high-temperature nitrogen environment. SiO2 is first reduced to vapor-phase SiO, and vapor-phase SiO reacts with nitrogen in the atmosphere to form silicon nitride.

The thermal decomposition method uses SiCl4 to react with ammonia gas at low temperature to obtain solid imino silicon (Si(NH2) or amino silicon (Si(NH2)4). These two silicides can be decomposed at high temperature to obtain silicon nitride powder The 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, and is suitable for the process of preparing high-quality silicon nitride for silicon powder. This method has become the most important method for commercial production of high-purity and high-quality silicon nitride powder

Overview of silicon nitride Si3N4 powder

Silicon nitride Si3N4 powder is an inorganic substance with a chemical formula of Si3N4. It is an important structural ceramic material with high hardness, inherent lubricity, wear resistance, atomic crystal, and high temperature oxidation resistance.

Application of silicon nitride Si3N4 powder

1) Manufacturing structural equipment: metallurgy, machinery, aviation, aerospace, etc.

2) Surface treatment of metals and other materials: such as molds, knives, turbine blades.

3) Composite materials: such as metal, ceramic and graphite composite materials, rubber, and plastics.

4) Colorless, transparent, self-lubricating and wear-resistant nano-particle film, used for high-level surface protection such as mobile phones and automobiles.

5) Ball bearings.

6) Ball valves and parts.

7) Corrosion resistant turbine.

Other applications of silicon nitride Si3N4 powder

Silicon nitride Si3N4 powder is used as high-grade refractory material. For example, SI3N4-SIC refractory materials and sic are used in blast furnace bodies and other parts, and SI3N4-BN materials and BN are used in horizontal continuous casting separation rings. Continuous casting separation ring is a fine structure ceramic material with uniform structure, high mechanical strength, good thermal shock resistance, and will not be wetted by molten steel, which meets the requirements of continuous casting process

Silicon nitride Si3N4 powder ceramic material has excellent properties such as high thermal stability, strong oxidation resistance, and high product dimensional accuracy. Since silicon nitride is a covalent compound with high bonding strength, it can form an oxide protective film in the air, so it has good chemical stability and will not be oxidized below 1200°C. The protective film formed at 1200~1600°C can be Prevent further oxidation, and will not be penetrated by many molten metals or alloys such as aluminum, lead, tin, silver, brass, and nickel. Or corrosion, but it can be corroded by molten magnesium, nickel-chromium alloys, stainless steel and other melts.

Silicon nitride Si3N4 powder ceramic materials can be used for high-temperature engineering parts, advanced refractories in the metallurgical industry, corrosion-resistant parts and seals in the chemical industry, tools and knives in the machining industry, etc. It can form a strong bond with silicon carbide, aluminum oxide, thorium dioxide, boron nitride, etc., so it can be used as a bonding material for different proportions of modification.

In addition, silicon nitride can also be applied to solar cells. After the silicon nitride film is coated by the PECVD method, it can not only be used as an anti-reflection film to reduce the reflection of incident light, but also in the deposition process of the silicon nitride film, the hydrogen atoms of the reaction product enter the silicon nitride film and the silicon wafer passivation Defects. The ratio of the number of silicon nitride to silicon atoms here is not strictly 4:3, but depends on the process conditions within a certain range. Internal fluctuations, different atomic ratios correspond to different physical properties of the film.

Used in ultra-high temperature gas turbines, aircraft engines, electric furnaces, etc.

Silicon nitride Si3N4 powder price

The price of silicon nitride Si3N4 powder will vary randomly with changes in production costs, transportation costs, international situations, exchange rates and the supply and demand of silicon nitride Si3N4 powder. Tanji New Materials Co., Ltd. aims to help various industries and chemical wholesalers find high-quality, low-cost nanomaterials and chemicals by providing a full set of customized services. If you are looking for silicon nitride Si3N4 powder, please feel free to send an inquiry to get the latest price of silicon nitride Si3N4 powder.

Silicon Nitride Si3N4 Powder Supplier

As a global silicon nitride Si3N4 powder supplier, Tanki New Materials Co., Ltd. has extensive experience in the performance, application and cost-effective manufacturing of advanced engineering materials. The company has successfully developed a series of powder materials (titanium nitride, silicon nitride, titanium nitride, etc.) high-purity targets, functional ceramics and structural devices, and provides OEM services.

Specification of Silicon Nitride Si3N4 Powder
Product Name:Silicon Nitride
Purity:99%
Particle Size:0.5um-1um (α phase)

Chemical Composition of Silicon Nitride Si3N4 Powder