Electrochemical Properties of TiN and ZrN Coated Ti-Hf Alloy

Abstract

The Ti-Hf alloy system forms α-β isomorphous system and does not form any intermetallic compounds, which is also beneficial for good mechanical properties. And in order to avoid the release of materials, surface modifications are generally carried out to form a TiN and ZrN layer on the surface. Electrochemical properties of TiN and ZrN coated Ti-Hf alloy by RFsputtering has been researched using various electrochemical methods. Ti-10wt%, 20wt%, 30wt%, and 40wt% Hf alloys manufactured by non consumable vacuum arc melting furnace. All the specimens were heat treatment at 1000°C for 24hr in Ar atmosphere followed by furnace cooling, respectively. The specimens were coated with TiN and ZrN respectively, by RF-magnetron sputtering method. The microstructures were conducted by using OM, EDX and SEM. The corrosion tests were carried out using potentiodynamic(PARSTAT 2273, EG&G, USA) and potentiostatic test in 0.9% NaCl solution at 36.5 ±1 °C. Microstructure clearly observed that lamellar structure translated to needle-like structure with increased Hf contents. From the analysis of TiN and ZrN coated layer analysis, TiN and ZrN coated surface showed columlar structure with 600nm and 100nm thickness, respectively. The corrosion resistance of TiN and ZrN coated Ti alloys were higher than those of the non-coated Ti-alloy in 0.9%NaCl solution, indicating better protective effect.