Microstructure, wear and friction behavior of CoCrAlTaY-xCNTs composite coatings deposited by laser-induction hybrid cladding

To improve the wear performance of CoCrAlYTa coating, part of the carbon nanotubes (CNTs) chemically reacted with Ta to form reinforcement phase (TaC), while the other CNTs were retained as lubrication phase. Subsequently, the CoCrAlYTa-xCNTs (x = 0, 1, 2, and 4; wt%) composite coatings were prepared by laser-induction hybrid cladding (LIHC), and the microstructure and wear resistance of coatings were systematically analyzed. Results show that the coatings are mainly composed of TaC, γ-(Co,Cr) and β-(Co,Cr)Al. As the CNTs content increases from 0 wt% to 4 wt%, the volume fraction of TaC increases from 13.11 vol% to 16.12 vol%. Meanwhile, the nano-hardness of γ-(Co,Cr) and β-(Co,Cr)Al are improved from 7.49 and 9.72 to 9.36 and 11.19 GPa, respectively. As a result, the microhardness of coating increases from HV 536.25 to HV 738.16, the wear rate decreases from 32.4 × 10^–3 to 6.1 × 10^–3 mg·m⁻¹, and the average friction coefficient decreases from 0.55 to 0.44. The good wear performance of the coating is attributed to the formation of TaC and the existence of remained CNTs lubricant film.