Effect of substrate hardness and surface properties on coatings properties through cold gas dynamic spray technique

The aim of this thesis is to investigate parameters affecting cold spray process: (i) substrate hardness (ii) substrate surface roughness (iii) standoff distance. To investigate the effect of substrate hardness on coating formation, different substrate hardness values were obtained by different heat treatments. To investigate the effect of substrate surface roughness on coating formation, four substrates having different average surface roughness was obtained via various metallographic sample preparation process. To investigate the effect of the standoff distance on coating formation, four different distance values were selected. Spherical Cu (d=10 μm, 99.9%) powders were sprayed on high purity Cu substrates. Compressed air at a nozzle inlet pressure of 6 bar was used as a process gas. Compressed air temperature varies between 400-600 ℃. Characterization of coatings were carried out by microscopic investigations, hardness, bond strength and electrical conductivity measurements. Microstructural characterization was carried out by optical and scanning electron microscope examinations and X-ray diffraction analyses.