Coatings and microstructures of monolithic TiB2 films and double layer and composite TiCN/TiB2 films from alkoxide solutions by thermal plasma CVD

Monolithic TiB2 films and double layer and composite TiCN–TiB2 films were deposited on Si wafers from a mixture of titanium tetra-ethoxide and boron tri-ethoxide solutions at a 1:2 mole ratio at 800 °C for 20 min by chemical vapor deposition in a thermal N2/H2 plasma. The TiB2 films were deposited without N2, while the double layer and composite TiCN–TiB2 films of various compositions were deposited by varying N2 flow rates in N2/H2 plasma. The surfaces and cross-sections of the films were observed by SEM, exhibiting the microstructures and thickness of the films. The relative atomic percentages of Ti, N, B, bonded and free C, and O in the films were determined semi-quantitatively from their XPS peak areas. Microstructures of the composite films with the composition 3TiC0.5N0.5/2TiB2 formed at N2 = 50 mL min− 1 were observed by TEM, revealing the sizes and orientations of the particles with the distribution of Ti and B elements in the film.