MICROSTRUCTURE AND SLIDING WEAR BEHAVIOUR OF STIRCAST TI-GR AND TI –FE METAL MATRIX COMPOSITES

S.S Sharma, Gowri Shankar M.C, U. Achutha Kini, Shivaprakash Y.M, P. R. Prabhu

Abstract: The type and weight percentage of reinforcement play important role in microstructure and sliding wear resistance of the composite. The low melting point nonferrous metal matrix composites Tin- Graphite and Tin-Iron metal matrix composites are cast by the liquid stir casting technique with up to 5 and 15 weight percentages of carbon and iron respectively as reinforcements. The sliding wear characteristics are important if the specimens are used as bearing materials for light duty applications. The specimens are polished and etched for microstructure examination to verify the homogeneous dispersion of reinforcements in the matrix. The microstructure examination reveals the uniform dispersion of reinforcements in the matrix. The specimens are also subjected to dry sliding wear on Pin –on –disc wear testing equipment and the weight loss method technique was used to find specific wear rate at the respective sliding distance. The cumulative specific wear rates and friction coefficients are plotted against sliding distance. The specific wear rate curves show the necessity of an optimum weight percentage of reinforcements in the composite to reduce the wear rate. The frictional coefficient versus sliding distance curves show the decrease in frictional force at higher sliding distances as the weight percentage of particulates increases. At higher sliding distances, in case of the Tin –Graphite composite the surface of the specimen observed to be smooth which makes the graphite particles to expose as flakes and act as solid lubricant to reduce wear. The scanning electron microscope image of the surface which is normal to the sliding surface also studied to verify the flake formation during wear. Both mild and severe wear regions are observed.

Keywords: particulate, metal matrix composites, stir casting, specific wear rate, friction coefficient.

DOI: https://doi.org/10.15623/ijret.2015.0402029