Analysis of the mechanical properties and microstructure of titanium surfaces designed by electromagnetic induction nitriding

Abstract

Nitride has high hardness and excellent wear resistance. It is frequently prepared on a material surface to improve material performance. The nitriding layer can be prepared in different ways, so the bonding strength and microstructure between the nitriding layer and the matrix differ, which will directly affect the surface mechanical properties of the material. In this study, pure titanium (TA1) was nitrided using electromagnetic induction nitriding, and the microstructure of nitriding layer was analysed using x-ray photoelectron spectroscopy (XPS), scanning electron microscopy-electron backscatter diffraction (SEM-EBSD) and scanning electron microscopy-energy-dispersive x-ray spectroscopy (SEM-EDS). In addition, the mechanical properties of the nitriding layer were studied using a nanoindentation and scratch tester. The experimental result shows a 20 μm induction nitriding layer composed of TiN, Ti2N and α(N)-Ti. The compound layer (Ti2N and TiN) was approximately 3 μm. The surface was contaminated with C and O elements, and evident segregation bands were found between the induction nitriding layer and matrix. The induction nitriding layer can considerably improve the wear resistance of titanium alloy, but the bonding force between the induction nitriding layer and matrix decreases owing to the segregation band.