Surface modification of A390 alloy with CaB6 composite coating

A390 alloy is widely used in piston production and owing to the adverse work conditions of piston, the demand for performance, especially surface performance of A390 alloy is very high. Grain refinement and Sr modification are widely used to improve the performance of A390 alloy, but this melt treatment for the improvement of surface properties is limited. In our study, in order to achieve excellent surface performance, a hard protective CaB6 composite coating was built on the surface of A390 alloy by laser cladding. Results show that the in situ synthesized CaB6/A390 composite coating exhibits ideal combination of good adhesion, high hardness and high abrasive resistance. Both of the surface and internal microstructure of A390 alloy can be modified and its performance can be improved remarkably owing to the formation of CaB6 composite coating. The brinell hardness of the coating can reach 136.2 HB, increased by 24.7 % and the abrasive resistance of A390 alloy can be improved by 17.7 %.