Spray forming of Al-Si-Pb alloys and their characterization

The spray droplets were deposited over a rotating copper substrate to achieve a disc shape preform. The thickness uniformity of the preform was found to depend on the preform distance from the nozzle, preform offset distance from the axis of the atomizer and inclination of the preform from the horizontal plane. Mathematical equations were developed to represent the thickness variation of the preform with aforementioned parameters. The porosity, hardness, strength, wear and microstructural studies of the Al-Si-Pb spray deposited alloys were conducted for different lead content, top to bottom distance of the deposit and the distance from centre to periphery of the deposit. Overspray and worn debris particles were also analyzed. Particles/droplets of two different types were observed to deposit on the substrate. First type particles were aluminum rich and second type were lead rich.