Sensitivity Study on Effects of Process Parameters on Spray Forming Pb—35Sn Alloy

The effects of atomisation gas pressure (0·1–0·2 MPa), flight distance (25–45 cm), and spray temperature (300–400°C) on the density and microstructure of Pb–35Sn deposits have been studied. As spray deposited microstructure showed equiaxed primary Pb phase, while as cast showed dendritic morphology. Atomisation gas pressure was found to have a significant effect on the size of primary phase, whereas flight distance and spray temperature had only limited effects. Atomisation gas pressure also had a greater effect on the fraction of primary phase produced and on the density of deposits than spray temperature and flight distance. The effect of flight distance is small because of the confounding influence of atomization gas pressure. The effects of gas impinging angle (45 and 90°) were mixed. Within the range of experimental variables studied, the volume fraction of primary phase increased with cooling rate for spray deposited materials, but decreased as the cooling rate increased for stirred cast materials. PM/0695