Solid particle erosion and corrosion resistance performance of nanolayered multilayered Ti/TiN and TiAl/TiAlN coatings deposited on Ti6Al4V substrates

Solid particle erosion by air born dust particles and corrosion by humid air and sea salt cause severe damage to the gas turbine blades and wind turbines. Combination of erosion and corrosion accelerates the damage process compared to the individual effects. The damage leads to the economic loss, pollution and low safety. In order to protect these components, ultra-thin multilayered erosion and corrosion resistant Ti/TiN and TiAl/TiAlN coatings with stress absorbing layers were developed on Ti6Al4V substrates using un-balanced magnetron sputtering process. Erosion resistance of Ti/TiN and TiAl/TiAlN coatings was tested according to the ASTM-G76-13 standards at four different impinging angles: 90 degrees, 60 degrees, 45 degrees and 30 degrees. Erosion tests were conducted at 400 degrees C with increasing erodent velocity (30 to 90 m/s) using alumina and silica erodent particles. Average erosion resistance of Ti/TiN and TiAl/TiAlN coatings was significantly higher than Ti6Al4V substrate. Corrosion resistance of the coatings was found to be almost one order better than Ti6Al4V substrate in 3.5% NaCl solution. Morphology and spectroscopic analysis of the erosion scars were studied using field emission scanning electron microscopy and micro-Raman spectroscopy, respectively. Chemical stability of TiAl/TiAlN was found to be better than Ti/TiN in 3.5% NaCl solution.