Preparation and Selective Laser Sintering of Nylon-12-Coated Aluminum Powders

The dissolution-precipitation process was developed to prepare nylon-12-coated aluminum powders, and functional parts were directly made using selective laser sintering (SLS) process from the composite powders. The microcosmic appearances of the composite powders and fractured surfaces of the SLS parts were observed by scanning electron microscope. The effect of the aluminum powder on the thermal properties of nylon-12 resin was studied by differential scanning calorimetry. The influences of the contents and particle sizes of the aluminum powders on the mechanical properties and dimensional accuracy of the SLS parts were investigated. The results show that: the aluminum particles are well coated with nylon-12 in the composite powders; the aluminum particles have good interfacial adhesion with nylon-12 and are homogeneously dispersed in the SLS parts; the aluminum particles can increase the melting and crystalline temperatures and crystalline rate of nylon-12; dimensional accuracy of the SLS parts can be improved by increasing the mass fraction of the aluminum powder; the tensile strength, flexural strength, and flexural modulus increase by about 10.4%, 62.1%, and 122.3% respectively when the mass fraction of the aluminum powder increases from 0 to 50%, while elongation at break and impact strength decrease by about 65.0 and 74.4% respectively; the tensile strength, elongation at break and impact strength all increase with decreasing particle sizes of the aluminum powders.