Wear and Corrosion Resistance of a Co-Based/Al2O3/Rare Earth Composite Laser Clad Coating on Steel
J.Y. Tian, P. Xu, Y. Shao, J.H. Chen and Q.B. Liu
Composite Co-based/Al2O3/rare earth (La2O3) mixture coatings were fabricated onto the surface of 4145H modified high tensile steel by CO2 laser cladding. Microhardness, microstructure and phase of the coating were analysed using a microhardness tester, an optical microscope, a scanning electron microscope (SEM) and X-ray diffraction (XRD). The wear and corrosion resistance of the composite coatings were investigated by a reciprocating friction wear tester and electrochemical workstation, respectively. The results indicate that the laser clad composite coating exhibited high average hardness of 627 HV0.2 and density by adding 5% Al2O3 and 0.4% rare earth (La2O3) to the Co-based alloy powder. The laser clad composite coating shows excellent wear resistance. The friction coefficient of the laser clad composite coating was 0.55, which is lower than the 4145H steel substrate at 0.7. The weight loss of the laser clad composite coating was only 1/3 that of the 4145H steel substrate. The corrosion resistance of the laser clad composite coating was also superior to that of the 4145H steel substrate.
Keywords: CO2 laser, 4145H steel, Co-based, Al2O3, rare earth, composite coating, laser cladding, microstructure, wear resistance, corrosion resistance