Abrasive wear CuPb30 alloy matrix composites reinforced with graphite particles
Małgorzata Łągiewka, Katarzyna Gielezy, Zbigniew Konopka, Andrzej Zyska, Maciej Nadolski
Quarterly No. 3, 2010 pages 289-293
DOI:
keywords: composite, abrasive wear, copper alloys
abstract Evaluation of the abrasive wear of copper alloy matrix composites reinforced with graphite particles was the aim of this study. CuPb30 alloy matrix composites with variable volume content of graphite particles, namely 5, 10, 15 and 20 vol. %, were produced. Composites were made by mechanical mixing of the liquid alloy with simultaneous introduction of a specified quantity of graphite particles, the average particle size ranging from 100 to 160 μm. Graphite was previously annealed at a temperature of 250°C in order to remove moisture. Composite suspensions and the alloy matrix were gravity cast to a metal mould. The resulting castings were of cylindrical shape with a diameter of 15 mm. The samples for abrasive wear test and the samples for metallographic examinations were cut out of the castings. Examining the microstructure of the studied composites, it was found that the parameters of the composite production had been chosen properly, the graphite particles were distributed evenly, and the sample did not have defects typical for metal matrix composites such as clusters of particles, porosity or oxide inclusions. Abrasive wear of composites and the matrix alloy has been measured as a weight loss of the sample undergoing a process of dry friction after passing 3000 m at a given load and rate of counter-sample turning. Mass loss measurements were made every 500 m. The samples were subjected to wear processes under variable load, namely 10, 20 or 30 N, to determine the effect of sample load on the magnitude of wear for the investigated materials. Also the matrix alloy was tested for comparison purposes. The studies show that the introduction of graphite particles to the CuPb30 alloy results in significant reduction of wear of the investigated material. The abrasive wear of composite material decreases with the increase in volume content of graphite. It was also found that increasing the load causes a significant increase in wear of both the composites and the matrix alloy, and with increasing volume content of graphite particles this effect is much greater. For the matrix alloy, increasing the load from 10 to 30 N increased the abrasive wear by 12 times in the final stage of the wear process, while for the composite containing 30% of graphite particles this increase in load increased the abrasive wear by about 600 times.