Boron carbide nozzles understand the role of boron carbide
The boron carbide nozzle does not react with acid and alkali solutions, and has high chemical potential, neutron absorption, wear resistance, and semiconductor conductivity. It is one of the most stable substances to acid, and it is stable in all concentrated or dilute acid or alkali aqueous solution.
After being treated with a mixed acid of sulfuric acid and hydrofluoric acid, it is calcined at 800 ° C for 21h in the air, and can completely decompose and form carbon trioxide and boron trioxide. When some transition metals and their carbides coexist, they have special stability.
However, the current research on boron carbide coatings is not deep enough. Compared with the research on other coatings, only a few papers abroad have discussed B4C as a hard coating, and there are fewer related research results in China. Based on the current research, the related research results of boron carbide coatings are reviewed, and the progress and future development of boron carbide coatings are discussed.
Preparation method of boron carbide coatingThe boron carbide nozzle coating has two structures: crystalline and amorphous. The hardness of the amorphous coating is lower than the hardness of the crystalline coating. There are many methods to prepare the boron carbide coating, mainly CVD and vacuum coating. ､ Adjustable RF magnetic sputtering ､ LCVD ､ Microwave method ､ Ion sputtering etc. In practical applications, different methods should be used to prepare boron carbide coatings according to specific requirements in order to obtain maximum benefits.
When ion sputtering is used to prepare B4C coatings, the most important factor affecting the coating performance is the sputtering distance. The sputtering distance has a great effect on the composition and microstructure of the coating. The B2O3 content increases with the increase of the sputtering distance. The density of the coating decreases with the increase of the sputtering distance, the elastic modulus decreases, and the increase of the sputtering distance leads to the decrease of the density. There are two reasons: First, when the particles are in a molten state, the gas accompanied by B2O3 formation Surrounded to form pores in the matrix.