Effect of coating thickness on microstructure, mechanical properties and fracture behaviour of cold sprayed Ti6Al4V coatings on Ti6Al4V substrates

Cold spray is a relatively new coating technology by which coatings can be produced without significant heating of the sprayed powder. This has gained attention in the aerospace industry as cold spray has the potential to restore damaged parts made of light metal alloys, like Ti6Al4V (Ti64 in short) components. Such repair requires high quality Ti64 coatings of varying coating thicknesses to fill the damages incurred in worn or corroded parts. However, the study of the effect of coating thickness for Ti64 coatings deposited on Ti64 substrates on their microstructure and mechanical properties has not been reported. In this work, high quality Ti64 coatings with different thicknesses were successfully deposited on Ti64 substrates. It was observed that the microstructure and mechanical properties such as low porosity levels, high hardnesses and strong adhesion strengths of the Ti64 coatings were maintained with increasing coating thickness, and thereby the process holds a great potential in the repair industries. The interface bond strength was also successfully measured with a glueless tensile test. As for the flexural strength, the thinner Ti64 coatings could conform to higher stress concentration point, better than the thicker coatings. The fracture characteristics of the coatings were also investigated.