Synthesis and deposition of Ni–20Cr powder using cold spraying

Abstract

Chromium nanoparticles were first synthesised using planetary ball mill in wet environment. The particle size was found to be nearly 60 nm, which was confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and particle size analyser techniques. Subsequently, Ni–20Cr alloy powder was synthesised by mechanical alloying of micrometre sized Ni (80 wt-%) and presynthesised Cr (20 wt-%) nanosized powders. X-ray diffraction revealed the solid solubility of Cr in Ni after ball milling for 20 h. The synthesised Ni–20Cr powder was subsequently deposited on SA 516 by cold spraying process. The as sprayed coatings were characterised by SEM/EDS, XRD, microhardness and porosity analyses. A nanostructured Ni–20Cr coating could be developed with an average thickness of 225 μm and microhardness of 335 HV having an apparent porosity of <1·5%.