Jierong Zhao

Effect of ZrB2 on the Microstructure and Wear Resistance of Ni-Based Composite Coating Produced on Pure Ti by Laser Cladding

ZrB2-reinforced Ni-based composite coating was fabricated on pure Ti substrate by laser cladding. The effect of ZrB2 doping on the microstructure and tribological properties of conventional NiCrBSi composite coating was investigated. It was found that the microhardness and wear resistance of pure Ti substrate are greatly improved after laser cladding. It is remarkable that the ZrB2 phase could further enhance the conventional NiCrBSi coating and generate higher hardness. During friction, due to the ceramic nature of ZrB2, that is, ultra-high melting point and hardness, the adhesive wear could be alleviated that occurs in conventional Ni-based coating, resulting in a better wear resistance. Thus, it is concluded that the incorporation of a ZrB2 phase is an effective and attainable way to improve the tribological properties of conventional Ni-based composite coatings.

Microstructure and Tribological Properties of ZrB2-Containing Composite Coating Produced on Pure Ti Substrate by Laser Surface Alloying

ZrB 2 -containing composite coating was fabricated on pure Ti substrate by laser surface alloying. The microstructure of the composite coating was investigated by means of X-ray diffraction and scanning electron microscopy (SEM). The friction and wear properties of ZrB 2 -containing composite coating sliding against a GCr15 steel ball at different normal loads and sliding speeds were evaluated. The morphologies of the worn surfaces were analyzed by means of SEM and three dimensional noncontact surface mapping. It is shown that the microhardness and wear resistance of the pure Ti substrate are greatly increased after laser surface alloying, due to the formation of hard ZrB 2 phase in the composite coating. Pure Ti substrate sliding against the GCr15 counterpart ball at room temperature is dominated by adhesion wear, abrasive wear, and severe plastic deformation, while ZrB 2 -containing composite coating involves only mild abrasive and fatigue wear when sliding against the GCr15 counterpart.