Influence of pretreatment of SiC on microstructure and properties of SiCp/A390

In this paper, two pretreatment methods of silicon carbide (SiC) particles were adopted: washing by hydrochloric acid (HCl) and high-temperature oxidation after washing by hydrochloric acid. The powder metallurgy method was used for better controllability of the prepared particles of the silicon carbide-reinforced aluminium alloy composites of A390. The changes in the morphology and composition of the silicon carbide particles after different pretreatment methods were studied; at the same time, the effects of the different pretreatment methods on the microstructure and mechanical properties of the composites were analysed. Research shows that washing by hydrochloric acid of the silicon carbide particles is mainly for cleaning, and high-temperature oxidation of the silicon carbide particles after washing by hydrochloric acid is mainly for producing a passivation effect, producing silicon dioxide. The high-temperature oxidation of the silicon carbide particles in the composites leads to the following: the particles distribute well; the interface bonding density improves; the resulting composites are without holes; the tensile strength and the relative density of A390 composites, reinforced by silicon carbide particles, after oxidation treatment, increased by 36% and 2·64%, respectively, compared to those of the original state of the silicon carbide particle-reinforced composites of A390.