Abstract
The effects of additions of copper-coated graphite particles on the spiral fluidity, casting fluidity, and hot-tearing characteristics of Al-11·8Si alloys were studied. The remelting and degassing characteristics of aluminium-graphite-particle composites made from copper-coated graphite particles are also reported. Spiral fluidity and casting fluidity of Al-11·8Si alloys decreases with an increase in the amount of suspended graphite particles of a given size and shape, and a decrease in the particle size or sphericity for a given vol.-%. Regression equations relating spiral and casting fluidity to surface area of suspended graphite particles have been derived. The decrease in spiral and casting fluidity of Al-11·8Si alloys owing to additions of copper-coated graphite particles is attributed to an increase in the effective viscosity of the melt. Additions of up to 4 wt-% of copper-coated graphite particles do not increase significantly the hot-tearing tendency of Al-11·8Si alloys. Degassing of Al-11·8Si-graphite composite melts by hexachloroethane leads to the rejection of graphite particles. However, these melts can be degassed readily with nitrogen.
Get full access to this article
View all access options for this article.