Wear-Resistant Zrn/Ti Functionally Graded Coating Prepared on Ta18 Alloy by Double Glow Plasma Alloying

Abstract

As an excellent structural material, α-Ti alloy with low shear deformation resistance makes it vulnerable to friction damage during service, which limits its further application. The coatings preparation on the α-Ti alloy through surface technology to improve its wear resistance has become one of the current research hotspots. The wear-resistant ZrN/Ti functionally graded coating (FGC) was prepared on TA18 titanium alloy by double glow plasma alloying technique. The morphology, phase structure, mechanical properties and wear behavior of ZrN/Ti FGCs were studied and analyzed. The coating is composed of ZrN ceramic phase in the topmost layer, followed by a transition layer of ZrN, TiN, and Ti2N phases, and α-Ti phase in the inner layer. The coating is dense and metallurgically bonded with the substrate. The coating exhibits better load bearing capacity and fracture toughnes. The wear tests conducted under different loads show that only slight damage occurred on the coating. The main wear form of the coating was peeling wear, and the ZrN layer on the surface was not worn through. More specifically, the Zr pre-diffusion treatment was used to increase the content of ZrN in the transition layer, thus reducing the unfavorable Ti nitride phase formed. Therefore, the stress concentration caused by the difference in elastic modulus between the different phases was relieved, ZrN/Ti FGC with continuous properties and good wear resistance was prepared.

Keywords: Functionally graded coating, Double glow plasma alloying, Wear resistance, Wear behavior, α-Ti alloy