In this study, pure titanium powder with an average size of 20 mm was treated by electroless nickel plating to obtain titanium-nickel composite/duplex powder. Two plating procedures were applied; continuous short period (CSP) and discontinuous long period (DLP) processes. The plated titanium powder particles as well as unplated ones were characterised by energy dispersive spectrometry (EDS), scanning electron microscopy (SEM), particle size analysis and X-ray mapping analysis methods. The nickel plated titanium powder was sprayed on the steel substrate by atmospheric plasma spray technique. Furthermore, the mixed titanium-nickel powder was also sprayed. The morphology of sprayed powders was compared with each other. It was found that nickel forms fine dispersed nodules on the surface of titanium powder particles in the CSP process, whereas it appeared as homogeneous layers on the surface of all the particles in the DLP process. Also, it was found that the mass deposited on the powder increased with the plating period. The sprayed nickel plated powder showed better microstructure than the sprayed nickel mixed one.

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In the present study, NiCrAlY coatings were applied on steel substrate using high velocity oxygen fuel spraying process. The spray parameters were varied in order to study their influence on the coating properties. Powder and coating microstructures were investigated by a combination of X-ray diffraction, optical and scanning electron microscopy as well as energy dispersive spectroscopy analysis. Bond strength and microhardness tests were also performed on the coatings. It was found that the propane flowrate, the oxygen flowrate, the spray distance and powder feedrate have a significant effect on the coating characteristics. Finally, with the aim of minimising oxygen content and maximising bond strength, the optimum parameters were selected as the preferred spray parameters. Experimental Development of coatingsA commercially available gas atomised Ni-22Cr-10Al-1Y (wt-%) powder (NI-343; Praxair Surface Technology

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