Influence of Atmospheric Plasma Spraying Angle and Concentration of (Ni/Cr) Nanosize on the Properties of (Y2O3- Ni /Cr) Composite Coating.

Abstract

    This research investigated the effect of  (Ni-Cr) nanopowder addition and spray angle on the mechanical, and structural properties of the prepared coating. First, the nickel and chromium powders were mechanically milled to reach the nano size. After the milling process, the sizes were reduced to the range between (55-75nm). Then the two elements were mixed in different weight ratios and then mixed with yttria at equal ratios. The powders were deposited using plasma deposition on steel substrates of type 304L. The mechanical and morphological properties of the resulting cermet coating were studied. It was found that the best results for mechanical and morphological properties and decreasing coating roughness when the spray angle (90?) and concentration (Ni60%, Cr40%), On the contrary, small spray angles increase of the coating defects. The mechanical properties were decreased and increasing of coating roughness when the spray angle is (30?) and the concentration of (Ni25%, Cr75%). Also, the use of nano-sized elements and mixing them with yttria led to a significant improvement in the properties. Increasing the nickel concentration of the sample (S3) was the best, and a homogeneous distribution of nickel and chromium elements was obtained and spread in the coating with yttria powder.The addition of nanoparticles will support the mechanical coating properties , due to their  good reaction and bindig with the coating layers which will  reduc of the coating defects.