Wetting in Al composites reinforced with SiC particles

Abstract

Aluminium matrix composites have been wide used essentially due to the good relation between weight and mechanical resistance. To develop a ceramic particle/matrix interface with good characteristics, it is essential to control the interface reactivity, avoiding the formation of undesirable reaction products such as Al4C3. Essentially, there are three methods to prevent the Al4C3 formation: Si addition to Al matrix, coating of the SiC particles and to promote a passive oxidation of SiC particles. The last method has been the most used due to its simplicity. In this work the formation of a SiO2 layer, in SiC particles surface, was made by exposing the particles to temperatures above 800ºC, in air. SiC particles with different grain size (12.8 and 37.6 µm), were used. The oxidation behaviour was followed by TGA. Also, the wettability between the SiC particles and the Al matrix (Al-10Si-4.5Cu-2Mg) was investigated by measuring the contact angle as a function of temperature and/or time. XRD, SEM, AFM and EDS techniques were used to characterize the SiC particles surface, before and after the tests.