Combined Effect of Substrate Temperature and Sputtering Power on Phase Evolution and Mechanical Properties of Ta Hard Coatings.

Ta hard coatings were prepared on PCrNi1MoA steel substrates by direct current magnetron sputtering, and their growth and phase evolution could be controlled by adjusting the substrate temperature (T_sub) and sputtering power (P_spu) at various conditions (T_sub = 200–400 °C, P_spu = 100–175 W). The combined effect of T_sub and P_spu on the crystalline phase, surface morphology, and mechanical properties of the coatings was investigated. It was found that higher P_spu was required in order to obtain α-Ta coatings when the coatings are deposited at lower T_sub, and vice versa, because the deposition energy (controlled by T_sub and P_spu simultaneously) within a certain range was necessary. At the optimum T_sub with the corresponding P_spu of 200 °C-175 W, 300 °C-150 W, and 400 °C-100 W, respectively, the single-phased and homogeneous α-Ta coatings were obtained. Moreover, the α-Ta coating deposited at T_sub-P_spu of 400 °C-100 W showed a denser surface and a finer grain, and as a result exhibited higher hardness (9 GPa), better toughness, and larger adhesion (18.46 N). [ABSTRACT FROM AUTHOR]