Silicon Carbide #4000 powder for Boron Nitride Coating
During the aluminum casting process, components such as runners, molds, and slag rings, which frequently come into contact with high-temperature molten aluminum, can be sprayed with boron nitride coatings to effectively enhance their high-temperature and corrosion resistance, thereby extending their service life. Adding Silicon Carbide #4000 powder (3-5µm silicon carbide powder) to boron nitride coatings can improve the coating’s performance in several ways. There are several advantages:
1. Hardness and Wear Resistance.
Silicon carbide #4000 inherently possesses high hardness, with a microhardness of up to 29-34 GPa. When added to boron nitride coatings, silicon carbide micropowder forms a rigid skeleton within the coating. When subjected to friction or wear, the silicon carbide micropowder effectively resists external forces, reducing wear and tear on the coating, significantly improving its hardness and wear resistance.
2. Thermal Conductivity.
Silicon carbide powder has excellent thermal conductivity, generally ranging from 83.6 to 460 W/(m·K). Adding silicon carbide powder to boron nitride coatings creates effective heat conduction pathways within the coating. When the coating is exposed to high temperatures, heat is rapidly transferred through the silicon carbide powder, improving the coating’s thermal conductivity.
3. Heat Resistance.
Silicon carbide has a high melting point (approximately 2700°C) and excellent chemical stability, enabling it to maintain stable performance even in high-temperature environments. Adding silicon carbide powder to boron nitride coatings improves the coating’s thermal stability, making it less susceptible to decomposition, deformation, or chemical reactions at high temperatures. Boron nitride coatings containing silicon carbide powder can withstand the erosion of high-temperature furnace gases and the thermal stresses of high temperatures, maintaining the coating’s integrity and stability and extending the life of the furnace.
4. Corrosion Resistance.
Silicon carbide 4000 grit powder exhibits excellent chemical stability and is resistant to attack by a variety of chemicals. Adding silicon carbide powder to boron nitride coatings enhances the coating’s resistance to chemical media. When the coating comes into contact with corrosive substances such as acids, alkalis, and salts, the silicon carbide powder acts as a barrier and protector, preventing these substances from corroding the coating and the substrate. Boron nitride coatings containing silicon carbide micropowder can effectively improve the corrosion resistance of equipment such as reactors and pipelines in the chemical industry, reducing corrosion damage.
5. Oxidation Resistance.
Silicon carbide forms a dense silicon dioxide oxide film at high temperatures. This film prevents oxygen from further diffusing into the coating, thereby enhancing the coating’s oxidation resistance. Adding silicon carbide micropowder to boron nitride coatings creates an oxide film on the surface that protects the coating and substrate from oxidation in high-temperature oxidizing environments, further extending the service life of spray molds.
