Reaction Pathways And Friction And Wear Properties Of The In-situ Copper Matrix Composites Reinforced By （TiB₂+α-Al₂O₃） Particles

In this paper, heat diffusion method (XD) was used to fabricate (TiB2+α-Al2O3) particulate reinforced copper matrix composites through in-situ reaction method successfully from Al-TiO2-B-Cu, Al-TiO2-B2O3-Cu system as raw materials. The reaction thermodynamics of the Al-TiO2-B-Cu and Al-TiO2-B2O3-Cu systems were calculated, and the SEM observation and EDS spectrum of the reaction products were analyzed, the phase composition of reaction products were identified combining with XRD, the reaction process model were built to explore the reaction mechanism. The results show that the Al-TiO2-B-Cu, Al-TiO2-B2O3-Cu system reacted in accordance with the reaction thermodynamics, and generate the α-Al2O3 and TiB2 particle reinforced phase respectively.Studies have shown that the reactions in Al-TiO2-B-Cu system during sintering process could be divided in four steps:the apparent activation energy of each reaction step was 590.5kJ-mol-1,708.0kJ-mol"’,354.6kJ-mol-1 and 346.4kJ·mol-1. Reactions in Al-TiO2-B2O3-Cu system during sintering process could be divided in two steps:the apparent activation energy of each reaction step was 168.9 kJ-mol-1 and 342.8kJ-mol-1, respectively.Results of friction and wear properties indicate:whether Al-TiO2-B-Cu or Al-TiO2-B2O3-Cu system, when volume fraction of reinforcement was 30vol.%, the friction and wear properties were the worst, because high volume fraction destroyed the copper matrix toughness, and caused a sharp increase in brittle, and easily broken in the process of friction and wear.For 20vol.%,10vol.% of the material, at room temperature, the 10vol.% volume fraction of the materials possess best friction and wear properties and distribution uniformity, friction furrows formed narrow. The friction coefficient varies among a small range. Friction and wear properties were stable.When condition was S=600m, L=20N, Al-TiO2-B-Cu composite material with 20vol.% has the best friction and wear properties. But with 10vol.% volume fraction of Al-TiO2-B2O3-Cu has the best friction and wear properties under the same condition.