Action of chills on soundness and ultimate tensile strength (UTS) of aluminum–quartz particulate composite

Abstract

Abstract The present investigation aims at producing cast aluminum alloy–quartz particulate composites in moulds containing metallic and non-metallic chills by dispersing quartz particles in molten aluminum alloy above the liquidus temperature, the size of the particles dispersed being between 30 μm and 100 μm. The dispersoid being added ranges from 3 to 9 wt.% in steps of 3%. The resulting composites cast using chills were tested for their strength and soundness. Results of the investigation indicate that (1) the strength of the composite developed is highly dependent on the location of the casting from where the test specimens are taken and also on the dispersoid content of the composite. (2) Chill thickness and chill material however does significantly affect the strength and soundness of the composite. (3) Soundness of the composite developed is highly dependent on the chilling rate as well as the dispersoid content. An increase in the rate of chilling and increase in the dispersoid content of the material both result in an increase in the UTS (ultimate tensile strength) of the material. The temperature gradient developed during solidification and VHC (volumetric heat capacity) of the chill used are the important parameters controlling the soundness of the composite. (4) Maximum interface temperature attained by the chill decreases with the increase in their VHC (volumetric heat capacity) and the total heat absorbed by the chill increases with increase in VHC. (5) Thermal properties of the end chills are used to determine the magnitude of the temperature gradients developed along the length of the casting solidifying under the influence of chills.