Characterization of graded ti suicide coating formed by thermal diffusion treatment of low pressure plasma sprayed silicon coating

The silicon coating was sprayed on titanium substrate by low pressure plasma spraying and the subsequent coating was heat-treated in vacuum. It is found that a titanium suicide coating with the composition changed gradually can be formed through thermal diffusion treatment of silicon coating sprayed by low pressure plasma an titanium substrate. The formed suicide coatings are characterized by optical microscopy, scanning electron microscopy, EPMA analysis and X-ray diffraction (XRD). The forming process of the suicide coating is investigated by examining the relationship between suicide coating thickness and thermal diffusion parameters. The results show that the composition of suicide coating changes gradually from TiSi₂ at the silicon coating side through TiSi and Ti₅Si₄ to Ti ₅Si₃ near substrate side. The thickness of such graded suicide coating is determined by temperature and holding time during heat-treatment. The diffusion of silicon into titanium substrate is mainly responsible for the formation of suicide. Moreover, the investigation of oxidation behavior of suicide coating shows that the formation of suicide coating on the titanium substrate can improve the oxidation resistance of titanium.