STUDIES ON PHYSICAL, MICRO-STRUCTURAL, AND SLURRY EROSION BEHAVIOR OF COLD-SPRAYED Ni-20Cr+TiC+Re COATINGS ON SA516 STEEL FOR HIGH-TEMPERATURE APPLICATIONS

In this paper, three kinds of Ni-20Cr coatings were deposited on SA516 substrate steel by cold sprayed coating technique. Physical properties (such as hardness, surface roughness, and residual stress) and slurry erosion behavior (with impingement angles of 30 degrees and 90 degrees) of cold-sprayed substrates have been evaluated. Moreover, a scanning electron microscope (SEM) examination has been performed to evaluate the morphological characterization of various coatings. It has been found that the residual stresses induced in the coated specimens exhibited compressive nature. Further, micro-hardness and surface roughness was observed to proliferate with the incorporation of titanium carbide (TiC) and rhenium (Re) in Ni-Cr coatings. Micro-hardness for Ni-20Cr+TiC and Ni-20Cr+TiC+Re was observed at 233.67 and 278.9 Hv, respectively, where Surface roughness for Ni-20Cr+TiC and Ni-20Cr+TiC+Re was observed at 9.86 and 11.68 pm, respectively. All types of Ni-20Cr coatings were quite efficient in reducing the erosion rate of the SA516 steel as compared to uncoated SA516 and most prominent of all was Ni-20Cr+Tic+Re coating. It was observed that at 30 degrees, weight loss for Ni-20Cr, Ni-20Cr+TiC and Ni-20Cr+TiC+Re was up to 0.00027, 0.00015 and 0.00012 g/mm(2), whereas at 90 degrees, weight loss was for Ni-20Cr, Ni-20Cr+TiC and Ni-20Cr+TiC +Re was up to 0.00024, 0.00014 and 0.00012 g/mm(2).