Production of bronze linings and performance tests

In this study, different rates of the graphite powders were added in starting powders of bronze based brake linings and produced by powder Metallurgy (P/ M) method with a different alloy composition. Bronze based linings were sintered under argon atmosphere in an alumina tube furnace. Pre-sintering conditions were 530°C for 15 min and sintering conditions were 800 oC for 60 min. Liquid phase sintering mechanism was dominant during sintering since the bronze based lining compositions contain low eutectic compositions such as tin and lead. Graphite was added to give extra porosity and arrange wear behaviors. Dry sliding tests were carried out with home-made lining wear test device under 157, 236 and 314 N loads with constant 0.1 m/s sliding speed. Wear test results showed that graphite addition increased porosity of the lining samples and changed wear properties. During wear test, graphite within the samples behaved as solid lubricant and affected wear lost significantly, coefficient of friction slightly. Therefore productions of low wear loss and high coefficient of friction bronze based brake linings were achieved. SEM examinations and optical microscope were carried out for polished and wear scars of bronze based linings. SEM images showed that wear mechanism of the lining was changed with graphite addition.