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 degrees C) on the density and microstructure of Pb-35Sn deposits have been studied. As spray dep osited microstructure showed equiaxed primary Pb phase, while as cast showed dendritic morphology. Atomisation gas pressure was found to hav e a significant effect on the size of primary phase, whereas flight di stance and spray temperature had only limited effects. Atomisation gas pressure also had a greater effect on the fraction of primary phase p roduced and on the density of deposits than spray temperature and flig ht distance. The effect of flight distance is small because of the con founding influence of atomisation gas pressure. The effects of gas imp inging angle (45 and 90 degrees) were mixed. Within the range of exper imental variables studied, the volume fraction of primary phase increa sed with cooling rate for spray deposited materials, but decreased as the cooling rate increased for stirred cast materials.