Deposition and wear resistance of Ti–B–N–C coatings on WC–Co cutting tools from alkoxide solutions by thermal plasma CVD

Double layered TiN/TiBC and composite TiBCN coatings were deposited on WC–Co cutting tools from titanium tetra-ethoxide (TTEO) and boron tri-ethoxide (BTEO) solutions at 800 °C for 20 min by chemical vapor deposition (CVD) in a thermal Ar/N2/H2 plasma. The double layered coatings were deposited in Ar/N2/H2 plasma for the first 10 min, followed by another 10 min deposition in Ar/H2 plasma. The composite TiBCN coatings of various compositions were deposited from the mixed solutions of TTEO and BTEO at a 1:2 mole ratio by changing the N2 flow rate. The crystalline phases of the coatings were identified by thin film X-ray diffraction. The surfaces and cross sections of the coatings were observed by SEM, revealing the microstructures and thickness of the coatings. The relative concentrations of Ti, N, B, bonded and free C, and O in the coatings were determined semi-quantitatively from the XPS peak areas. The composite TiBCN coatings deposited on WC–Co cutting tools exhibited superior flank and crater wear resistance compared with commercial TiN coatings.