Effect of parameters of spray forming on porosity

In this study, a coating layer has been formed on a cylinder with spray forming technique by using aluminum powders which has atomized by close coupled nozzles which have been designed and produced before. Since porosity has a major effect on the mechanical properties of spray formed parts, effect of the parameters on the porosity have been investigated in order to have higher mechanical properties. İn the experimental step, a spinning cylindrical tube has been located straight forward to the atomization direction. During the experiments, the atomized aluminum powder has been sprayed with the help of nozzles when they were yet in the liquid form. The cylindrical tube rotates at different speed and the coating has been applied from 3 different distances as being 135, 165 and 200 mm. Therefore, a coating layer has been deposited on the surface of cylinder. İn the study, the protrusion of 4, 6 and 8 mm at nozzle tip and 5, 10 and 15 bar pressure have been used besides of the spray distance. Each experimental condition has been repeated 3 times. Samples have been taken from the center and side of the each coated parts in order to examine their porosity, bonding with powders and substrate, powder sizes and powder shapes under an optical microscope. The effect of newly structured grains on hardness has also been examined using a micro hardness tester.