Fabrication and characterisation of graphite/alumina reinforced copper composites

The infiltration of graphite/alumina preforms with a bronze alloy has been investigated taking into account the influence of the binder type, the grap hite/alumina content in the preform and the percentage of binder in water. The preforms showing an acceptable rigidity have been infiltrated with a Cu Sn12 bronze alloy by squeeze casting considering two different pouring temp eratures. The composite produced has been characterised in terms of density , Brinell hardness, coefficient of thermal expansion, as well as friction a nd wear behaviour. The coefficient of friction for the bronze matrix compos ite is around 0.17, being three times lower than that shown by the unreinfo rced copper alloy. Given the contact geometry (ball of steel against a plan ar sample) and testing conditions (20 degreesC, dry sliding, 40% humidity), the composite wear rate is around twenty times lower that of the bronze, b eing 10(-6)mm(2)/kg for the composite and 2 x 10(-5) mm(2)/kg for the bronz e. (C) 2000 Kluwer Academic Publishers.