Study on Preparation and Anti-laser Irradiation Performance of Boron Carbide Coating Prepared by Vacuum Plasma Spraying

B4C is a non-oxide ceramic with strong covalent bonding. It has high melting point, low density, high hardness, high elastic modulus, etc. It can be used as a wear-resistant material and anti-nuclear irradiation material I1, 2. In stainless steel The B4C coating is deposited on the surface of substrates such as low-alloy steels, which can combine the good mechanical properties and processability of the metal substrate with the good wear and anti-nuclear radiation properties of the coating. The main methods for preparing b4c coatings are: chemical vapor deposition (cvd), reactive sintering, and plasma spraying. Plasma spraying is considered to be characterized by high jet temperature, controllable coating thickness, high bonding strength, and easy operation. An effective method for preparing b4c coatings. However, b4c has problems such as high temperature oxidation and gasification during spraying process. Atmospheric plasma spraying cannot produce B4C coatings with good performance. Someone has developed a special protection technology under inert gas protection. For plasma spraying, although B4C coating was obtained, partial oxidation products still existed in the coating. Vacuum plasma spraying has the advantages of low oxygen content, composition, and powder in the coating chamber with controlled atmosphere and fast jet velocity. In this paper, the b4c coating was deposited on the stainless steel surface by vacuum plasma spraying. The composition, structure, deposition efficiency, bonding strength and laser irradiation resistance of the coating were characterized.

The numerical value of the bonding strength of 2 shows that the bonding strength of the coating is also high when the flow rate of argon/hydrogen gas is relatively low, that is, the flow rate of hydrogen gas is relatively high.

3.3 Anti-laser Irradiation Performance Surface morphology of stainless steel substrate and VPSB4C coating after laser irradiation for 3 min is shown in Fig. 8 and (a). It can be seen that after laser irradiation, pits are formed on the surface of the stainless steel and pit edges are generated. Obvious bulging, indicating that stainless steel laser irradiation after 3min after the surface morphology of the stainless steel substrate by laser irradiation 3 seconds after the VPSB4C coating surface morphology of the laser due to ablation deformation. As can be seen from the high ((b)) photographs, more cracks appear in the pits, and recrystallization of the stainless steel after melting can be observed. As shown in the morphology of the B4C coating, pits appear on the coating surface, but no obvious cracking and recrystallization occurs. The mass loss of the stainless steel substrate and the B4C coating after irradiation shows that the B4C is deposited on the stainless steel substrate. After coating, the mass loss of the laser irradiation was significantly reduced, indicating that the B4C coating has good resistance to laser irradiation.

4 Conclusions The B4C coating can be prepared with finer powders. Compared with the VPSB4C dense VPSBjC coating, the higher power and greater hydrogen flow during the spraying process can improve the melting state of b4c during the spraying process and help to coat the coating. The layer deposition efficiency is improved, and the prepared coating has a relatively high bonding strength.

Under the appropriate process parameters, the deposition efficiency and bond strength of the coating can reach 72% and 49 MPa, respectively. After the deposition of the VPSB4C coating on the stainless steel substrate, its anti-laser irradiation performance is significantly improved.

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