Microstructure and tribological properties of AlCrFe2Ni2W0.2Mo0.75 high-entropy alloy coating prepared by laser cladding in seawater, NaCl solution and deionized water

Abstract Ocean engineering equipment frequently undergoes tribological impacts during service, resulting in an accelerated deterioration of ocean materials. Thus an effective strategy by introducing high entropy alloy coating was proposed to protect ocean engineering equipment. Accordingly, a new wear-resistant AlCrFe2Ni2W0.2Mo0.75 high entropy alloy coating was designed and deposited on Q235 steel by laser cladding. The corresponding microstructure, microhardness and tribological properties in artificial seawater, 3.5 wt% NaCl solution and deionized water were investigated deeply. The microstructure of coating presents a weave-like morphology and consists of BCC and ordered B2 phases. Its hardness is approximately 630.88 HV, which is almost 4.6 times than that of substrate. Besides, the coating exhibits better tribological properties than Q235 steel substrate and SUS304 in NaCl solution and seawater. And the friction and wear of coating in seawater are the mildest among all environments. It is mainly due to the lubrication effect of Mg(OH)2, CaCO3 and Ca(OH)2, as well as the formation of other metal hydroxides and oxides on worn surface of coating, which isolates and reduces wear and friction, resulting in a decrease in friction coefficient and wear rate. Besides, the coating has better corrosion resistance than Q235 substrate and SUS304 in seawater. These suggest that the AlCrFe2Ni2W0.2Mo0.75 coating is a promising material for surface protection of ocean engineering equipment.