Microstructure and tribological performance of Ni60-based composite coatings on Ti6Al4V alloy with different Ti3SiC2 ceramic additions by laser cladding

Abstract

The Ni60-based self-lubricating composite coatings on the surface of Ti6Al4V alloys were successfully fabricated by laser cladding using different Ti3SiC2 ceramic additions. The microstructure, phase compositions and microhardness of the ceramic coatings were analyzed, the dry-sliding tribological properties and corresponding wear mechanisms of Ti6Al4V alloy and these ceramic coatings at different temperatures (RT, 300, and 600 °C) were also investigated systematically. The results show that the coatings are mainly comprised of γ-Ni solid solution, intermetallic compound TixNiy, hard phase TiC, TiB and Ti3SiC2 ceramic phase, the microhardness of the coatings was significantly improved compared with that of the substrate. Due to the synergetic action of the Ti3SiC2 lubricant and hard phase, the composite coatings possess better friction reduction and wear resistance performance than the Ti6Al4V alloys at all test temperatures. The lowest coefficient of friction (COF) (0.30 at 600 °C) was obtained when the composition was Ni60-5% Ti3SiC2(wt%), and the most excellent wear resistance (0.63 × 10−5mm3/Nm at 600 °C) was observed in the coating with composition of Ni60-15% Ti3SiC2(wt%). The abrasive wear, adhesive wear as well as oxidation wear are the main wear mechanisms of the Ti6Al4V alloy at 600 °C, while the coatings (composition: Ni60-10% Ti3SiC2 and Ni60-15% Ti3SiC2) are predominated by hard phase peeling off, three-body abrasive wear and oxidation wear at 600 °C.