Preparation and High Temperature Tribological Properties of Nano-Multilayer CrAlN/CrN Coating on Surface of Inconel 718 Alloy

Abstract

For improving the surface hardness and high temperature friction wear properties of Inconel 718 alloy, CrAlN/CrN coating was prepared on the alloy surface by multi-arc ion plating technique. The microstructure and mechanical properties of the coating were analyzed and characterized using X-ray diffractometer (XRD), X-ray photoelectron spectrometer (XPS), scanning electron microscopy (SEM), nanoindentation and scratching instruments. In addition, the friction properties of the coating were tested at room temperature, 350 ℃ and 650 °C using a UMT friction and wear tester, and the morphological characteristics, elemental distribution and physical phases of the wear marks were analyzed to discuss the friction and wear mechanisms of coatings at different temperatures. Results showed that the nano-multilayer CrAlN/CrN coating with dense microstructure was mainly composed of face-centered cubic CrN phase, which presented a selective orientation of (200) crystal plane. The CrAlN/CrN coating had good mechanical properties on the surface of Inconel 718 alloy with hardness and bonding force of (29.3±1.2) GPa and 70.4 N, respectively. Meanwhile, the coating had excellent wear resistance at room temperature and 350 ℃, with wear rates as low as 1.5×10-6 mm3/(N·m) and 1.7×10-6 mm3/(N·m), respectively, and the dominant wear mechanisms were abrasive wear and fatigue wear respectively. At 650 ℃, the coating reached the lowest coefficient of friction (0.33), but the wear rate increased, mainly in the form of abrasive wear.

Keywords

• nano-multilayer|craln/crn coating|microstructure|mechanical properties|high temperature tribological properties