Outstanding wear resistance of plasma sprayed high-entropy monoboride composite coating by inducing phase structural cooperative mechanism

Surface wear-resistant coatings are an effective way to protect tools and provide certain desired properties; however, these coatings often fail prematurely owing to their low plastic deformation ability. High-entropy monoboride (VCrMoWNi)B with an super hardness is a promising material for wear resistance. To balance the high hardness and plastic deformation ability of coating, a novel design concept for the plastic phase precipitate reaction was developed based on the crystallization conditions of the different elements of the composite during deposition of the plasma sprayed high-entropy monoboride (VCrMoWNi)B-Ni₂B (HEMB-Ni₂B) composite coating. The microstructure evolution, hardness, and wear resistance mechanism of the HEMB-Ni₂B coating were thoroughly investigated. Because the second phase Ni₂B is beneficial for producing plastic deformation and absorbing large strain energy, the cooperation effect between the super hardness of HEMB and large plastic deformation ability of Ni₂B can significantly enhance the wear resistance of the HEMB-Ni₂B coating. Particularly, a friction coefficient as low as 0.13 for the HEMB-Ni₂B coating and outstanding wear resistance are achievable. This study paves the way for the design of high-entropy ceramic coatings with excellent mechanical performance. Moreover, it has a high practical application value in the field of wear resistant coatings.