Oxidation, Mechanical and Tribological Behaviors of the Ni/cBN Abrasive Coating-Coated Titanium Alloys

In order to improve the oxidation and wear resistance of blades tip of titanium alloys as well as the sealing performance of the gas turbine engine, a Ni/cBN abrasive coating was prepared on titanium alloys through composite electroplating. Oxidation, mechanical and tribological properties of the abrasive coating were investigated. Furthermore, the effect of the oxidation on the mechanical and tribological properties was also evaluated. Oxidation results revealed that the abrasive coating underwent slight oxidation within 700 °C. Meanwhile, some intermetallic compounds, Ni3Ti, NiTi and NiTi2, were formed at the coating/substrate interface during oxidation. Due to the pinning effect of cBN particles and the different thermal expansion coefficients of the coating and substrate, the coating/substrate interface was cracked after oxidation at 700 °C. Tensile results showed that the presence of coating reduced the strength of the alloy significantly at room temperature, while only marginal variations of the strength of the coated and uncoated specimens at elevated temperatures. Besides, the wear tests indicated that the coating had the excellent cutting ability and wear resistance, which can effectively protect the blades tip of titanium alloys. As the temperature increased, the wear resistance decreased due to the decrease in the mechanical properties of the Ni/cBN coating.