The effect of NH{sub}3 plasma pre-treatment on the adhesion property of (Ti{sub}1-xAl{sub}x)N coatings deposited by plasma-enhanced chemical vapor deposition

摘要

(Ti{sub}(1-X)Al{sub}X)N has been coated on high speed steel (HSS) substrate by a plasma-enhanced chemical vapor deposition (PECVD) process from a gas mixture of TiCl{sub}4, AlCl{sub}3, NH{sub}3, H{sub}2, and Ar. Prior to deposition, the substratewas treated by NH{sub}3 plasma in the same deposition chamber. It has been found that CrN was formed on the substrate surface after the NH{sub}3 treatment. Iron compounds which are known to degrade the adhesion property of the coating, however, were notobserved. The lattice parameters of the HSS and the coatings increased after the NH{sub}3 treatment by the incorporation of nitrogen atoms. The microhardness of (Ti{sub}(1-X)Al{sub}X)N, however, was not changed by the pre-treatment. The adhesion strengthof the coatings without the NH{sub}3 treatment decreased considerably when X{sub}Al in (Ti{sub}(1-X)Al{sub}X)N was greater than 0.15, which could be increased markedly by the substrate pretreatment with NH{sub}3 plasma. The improvement of the adhesion was achieved by the decrease of the stress gradient at the interface of the substrate and the coating resulted from the formation of TiN prior to (Ti{sub}(1-X)Al{sub}X)N as well as by the different lattice parameter change between the substrate and thecoating after the plasma treatment. Oxide removal on the substrate surface also contributed to the adhesion improvement.