Energy absorbing nano-porous Ti layers assisted erosion-corrosion resistant Ti/TiN multi-layered coatings for gas turbine compressor blades

Solid particle erosion (SPE) resistant coatings extend the life of gas turbine compressor blades and improve the safety of flights. Among different types of these coatings, nanolayered multi-layered and nanocomposite coatings proved to be more efficient. Further increase in the efficiency of these coatings can be achieved by introducing energy-absorbing metal porous layers. Here, we report the development of three different types of SPE and corrosion resistant Ti/TiN multilayer coatings (thickness ∼9 μm) on Ti6Al4V substrates using a sputtering technique. The coatings contain three stacks of Ti/TiN (7.3 nm) bi-layers separated by two energy-absorbing Ti layers of different porosity in each coating. The Ti film deposited at 4 mTorr chamber pressure showed a mix of ω and α phases with high porosity. The SPE studies were conducted according to ASTM-G76 standards at a temperature of 400 °C. The corrosion properties of the coatings were studied by potentiodynamic polarization in a 3.5 wt% NaCl solution. The coatings with energy-absorbing porous Ti layers showed better SPE-resistant performance compared to the coating with dense Ti layers. Whereas, vice versa behaviour was in the case of corrosion resistance performance. SPE mechanism is also analysed using field emission scanning electron microscopy images of erosion scars.