Tribological and braking performance comparison of martensitic stainless steel coatings deposited by laser cladding and HVOF

Abstract In this study, a martensitic stainless steel (431L grade) based coating material was applied to brake discs produced from grey cast iron (GG20) using laser cladding and HVOF methods and the braking performance was investigated in terms of tribological, NVH and corrosion. The experiments were conducted using original ventilated front brake discs and brake pads manufactured. The wear resistance and braking performance of coated and uncoated disc-pad pairs were simulated using a full-scale inertial dynamometer. Brake performance was compared based on the friction coefficient trend and brake torque values according to the bench test results. Experimental test results show that the coated disc has a more stable friction coefficient, indicating better braking performance with more uniform wear. By comparing the wear ratio caused by the disc-pad friction surfaces before and after the test, it was found that the couple of coated disc-pad had less amount of wear with higher wear resistance. Compared to uncoated discs, laser cladding performed 4.5 times better and HVOF 1.9 times better. In addition, the corrosion test results demonstrated that the coating significantly improved the corrosion resistance. The laser cladding brake disc exhibited a well-bonded and uniform coating layer with strong metallurgical integrity.