The effect of surface alloying of Ti powder for vacuum plasma spraying of open porous titanium coatings

By choosing the right conditions it is possible to produce thick open porous titanium coatings by means of vacuum plasma spraying. In this work such coatings were produced using both pure and surface alloyed Ti precursors. The effect of silicon, as the alloying element, on the final coating in terms of the particle–particle interface, coating appearance and mechanical strength of the coating was of particular interest. The coatings produced were ∼1 mm thick and exhibited a porosity of 45–60%. Silicon was still found to be located primarily at the surface of the particles and at the interfaces. It formed mixed phases with Ti of varying Si content up to ∼7 wt.%. The local hardness measured on a coating cross-section increased with increasing Si content. The mechanical properties in terms of shear strength could be increased by a factor of about two by use of the surface alloyed precursor powder.