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

Abstract

ZrB2-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 ZrB2-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 ZrB2 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 ZrB2-containing composite coating involves only mild abrasive and fatigue wear when sliding against the GCr15 counterpart.