WEB Effect of Si doping on microstructure and oxidation resistance of CVD TiN, TiCN and TiAlN hard-coatingsWednesday (01.01.2020) 00:15 - 00:30 Part of:
Under the guidance of thermodynamic and kinetic simulations, Si was doped to CVD TiN, TiCN and TiAlN coatings which were deposited on WC-Co cemented carbide by low pressure chemical vapor deposition technique (LPCVD). Several analytical techniques, such as scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Nano-indentator, were employed for the characterization of surface morphology, microstructure, phase identification, oxidation resistance, phase stability and mechanical properties of the coatings. The measured chemical compositions, phase structures and deposition rates for both TiSiN and TiSiCN coatings are in good agreement with thermodynamic calculations and computational fluid dynamics (CFD) simulations. By means of high-resolution transmission electron microscopy (HRTEM), the TiSiN and TiAlSiN coatings were detected to be composed of cubic nano-crystalline TiN/(Ti,Al)N embedded in an amorphous Si3N4 matrix, while TiSiCN coating was composed of nano-crystalline Ti(C,N) with amorphous SiCxNy. After annealing in air at 973 K for 1 h, TiSiN and TiSiCN coatings kept intact with a weight gain of 0.002% and 0.009% while TiN and MT-Ti (C, N) coatings were completely oxidized with a weight gain of 0.605% and 0.114%, respectively.