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 acid-stable substances and is stable in all concentrated or dilute acid or alkali aqueous solutions.

After being treated with a mixed acid of sulfuric acid and hydrofluoric acid, calcined at 800 °C for 21 h in air, it can be completely decomposed to form carbon trioxide and boron trioxide. There is special stability when some transition metals and their carbides coexist.

However, the current research on boron carbide coatings is not deep enough. Compared with the research on other coatings, only a few foreign papers have discussed B4C as a hard coating, and there are even fewer related research results in China. On the basis of the current research, the related research results of boron carbide coating are reviewed, and the progress and future development direction of boron carbide coating research are discussed.

Preparation method of boron carbide coating

The boron carbide nozzle coating has two structures, crystalline and amorphous. The hardness of the amorphous coating is lower than that of the crystalline coating. There are many methods for preparing the boron carbide coating, mainly including CVD, vacuum coating, and adjustable radio frequency 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, and strive to obtain maximum benefits.

When ion sputtering is used to prepare B4C coatings, the most important factor affecting the performance of the coating is the sputtering distance. The sputtering distance has a great influence on the composition and microstructure of the coating, and the content of B2O3 increases with the increase of the sputtering distance. The density ratio of the coating decreases with the increase of sputtering distance, and the elastic modulus decreases. There are two reasons for the decrease of the density ratio with the increase of sputtering distance: one is that when the particles are in the molten state, the gas formed with B2O3 It is surrounded by the matrix to form pores.