Effects Of Sintering Additives And Melting Infiltration Sintering On Selective Laser Sintering Of Alumina

Conventional manufacturing processes, such as casting, machining, welding, require expensive investment in tooling which make them economically attractive when a large number of components are desired. Powder-based layer-additive manufacturing, selectively fusing and without part-specific tooling or human intervention, the selective laser sintering (SLS) process can be very cost saving and fast for producing prototypes and short-run tooling of great complex over conventional methods.Using aluminum as binder in selective laser sintering (SLS) process of alumina has advantages, such as that the Al can totally oxidized to alumina and simplifies the post heat treatment procedures. However, due to the expansion caused by oxidation of aluminum, it is very difficult to obtain dense samples. In the present work, by adding sintering additives and using melting infiltration sintering method the density and strength of the samples made by SLS with aluminum binder are enhanced greatly.Two main powders were used in this work, alumina with average particle size 3μm, aluminum with average particle size 75um. The effect of laser power and scanning speed on strength and accuracy of green part at different wt% of Al is analysed, while the scanning space and layer thickness are predetermined, and the optimal sintering parameters were determined.The main effects of compound additives on density, strength and accuracy of SLS parts are summarized as follows:the density and strength were increased greatly, but the shrinkage is notable.The using of the melting infiltration sintering can further increase the density, and greatly increase the accuracy, however, it decrease the strength. At the best accuracy in the study, the density is 2.2g/cm3, strength 57.5MPa.Therefore, based on the study of compound additives and melting infiltration sintering on density, strength and accuracy of SLS parts, complex alumina parts with acceptable strength and accuracy can be manufactured, which is very meaningful for widening application area and commercialization.