The effect of silicon doping on the mechanical and corrosion properties of tantalum carbide coating deposited by magnetron sputtering technique

In this study, Ta, TaC and TaSiC coatings have been deposited by a non-reactive magnetron sputtering method, and their structural, microstructural, mechanical, and corrosion properties have been investigated. XRD results revealed the presence of α-Ta and TaC0.6 phase structures in the Ta and TaC coatings, respectively. However, the TaSiC coating showed a quasi-amorphous structure. Additionally, the Ta coating showed a columnar microstructure with rough topography and tensile residual stress, while the addition of carbon and silicon resulted in the compactness and smoothness and domination compressive residual stress in the TaC and TaSiC coatings. Nanoindentation results showed that the addition of carbon to the Ta coating increased the hardness by four times, however the addition of silicon to the TaC coating had an adverse effect on the hardness of the coating. The corrosion studies revealed that the coatings have a cathodic nature with respect to the ST37 substrate, making the samples susceptible to galvanic corrosion. Furthermore, the addition of carbon and silicon was found to improve the corrosion resistance of the coatings by increasing the coating compactness and decreasing the density of open porosities.