DEVELOPMENT OF BRONZE-TIC COMPOSITES AND ITS TRIBOLOGICAL BEHAVIOR

Abstract

The tribological behavior of Cast Lead-free Copper alloy (C903000) commercially better known as Tin Bronze is well established in the area of antifriction materials due to its duplex structure, one soft and another hard phase structure as studied earlier. In present work, an attempt has been made to study the tribological properties of Sn-bronze-TiC composites develop via stirred casting, so as examine the wear response of these composites. The purposes of adding TiC to impart high wear resistance and low coefficient of friction to the base alloy, since the phase TiC itself has hardness approx. 3000VH and low coefficient of friction. Both Sn-bronze and Sn-bronze-TiC composites are subjected to identical test of dry sliding friction on pin-on-disk machine at fixed sliding speed at I m/s but at three different loads of 14.7 N, 24.5 N & 34.3 N against a steel disc counterface. The wear coefficient, and weight losses of both base alloy and composites of wear test specimens were measured. The friction and wear characteristics of Sn-bronze-TiC composites would be compared with Sn-bronze with a view to assess the working capability of composites with respect to the base alloy. The wear characteristics of Sn-bronze-TiC composites have been correlated with their microstructural features, while the wear mechanism which are operative have been studied through analysis of wear surface and wear debris, before and after the test, using Scanning Electron Microscope (SEM) and X-Ray Diffraction. The wear coefficient of bronze was higher than the Sn-bronze-TiC composites specimens for all applied loads due to presence of hard TiC phase in the matrix of Sn-bronze. Dispersed reinforced TiC particles in the bronze matrix are responsible for the effect of transfer layer on the wear coefficient surface roughness and variation in the weight of the wear test specimens and the counterface. As a result, the tribological properties of Sn-bronze-TiC composites material increased fairly as compared to that with Sn-bronze. Thus, this study clearly indicates that it is possible to develop economically friendlier Sn-bronze-TiC composites, by simple stirred casting technique, having much improved wear characteristics over that of Sn-bronze.