Development of surface modified Cu Sn bronze alloys and determination of their hardness wear rate and coefficient of friction

Abstract

An investigation was carried out to evaluate the effect of surface modification process on the hardness, the wear rate and the coefficient of friction of Cu-Sn bronze alloys. The surface modification process was carried out by melting the surface of the substrate and allowing to solidify progressively by using the Gas Tungsten Arc (GTA) as the heat source. The effect of GTA process parameters on the hardness, the wear rate and the coefficient of friction of the Cu-10wt%Sn alloy was assessed. The effect of Sn content on the hardness, the wear rate and the coefficient of friction of surface refined Cu-Sn bronze alloys was also evaluated by varying the Sn content in the present study. Further, Surface modification experiments were carried out with Ni as the alloying elements. Electroplating technique was used for coating Ni on the surface of the substrate. Microstructural evaluation was carried out using an optical microscope. The Vickerand#8223;s hardness tester was used to measure the micro hardness of the alloys. Wear testing was carried out as per ASTM standard using the Pin-on- Disc wear tester. The concentration of Ni dissolved in the modified layer was measured along the depth direction using the EDAX analysis. It was observed that a refinement in the grain structure occurred for the surface modified specimen due to fast cooling occurring during solidification. The surface modification process improved the hardness and the wear properties of the alloy. It was also found that the surface hardness is dependent on the electrode diameter and the arc length. Also the hardness and the wear rate were found to be dependent on the Sn content of the alloy. Further, the addition of Ni was found to be highly effective in increasing the hardness of the parent substrate and reducing the wear rate when compared to the addition of other alloying elements like Ti, TiC and Cr to the Cu-based alloys. newline