Plaster And Polyurethane Based Powders For 3D Printing Rapid Prototyping And Post-process Of 3dp Specimens

Three-dimensional printing(3DP) is one of such technologies that employs ink-jetprinting technology for processing powder materials. It has many advantages such as printinga broad variety of materials,simple molding process, environmental protection and colorfulprinting,The 3DP technology is broadly employed in applications involving industrial molds,medical fields, construction and other fields.gypsum based powder formulation was developed for 3DP. Gypsum was selected as themain component of the powder material, silica powder was selected as the flow regulators toreduce the van der Waals interparticle attractive force and increase the flow properties ofgypsum particles. We have discovered the optimum gypsum based formulation by the uniformdesign experiment, the dosage of gypsum is 83.7%, PVA 12.6%, silicon particles 0.5%, Al2O33.2%. This powders were used as raw materials,and water-based binder as a jetting media forfabrication by a 3DP machine. After building, all the specimens were left in the machine for 2h before being taken out. It was observed that the compressive strength is 1.95 MPa. We alsosummarized the problems during the processing of molding powders and analyzed the reasonof defective specimens.Due to the 3DP specimens are not sufficiently strong enough, we put the specimensimmersing in the infiltrant A and B to improve the performance. The influence of differentfilling enhancers, i.e. infiltrant A, base materials of infiltrant B and dosage of waterborneepoxy emulsion as well as immersion time on the compressive strength, dimensional changeand water absorption property of the 3DP specimens was examined. The best immersion timefor the 3DP specimens into infiltrant A and infiltrant B was 130 s and 35 s respectively. Afterimmersed in the infiltrant A and subsequently in infiltrant B, the 3DP specimens were capableof low water absorptivity, high compressive strength and smooth surface.Finally, gypsum polyurethane based powder was studied. The influence of TPU dosageon the properties of surface structure, dimensional change, bulk density, porosity, waterabsorption and strength of 3DP specimens were demonstrated in this study.It showed that asthe content of TPU increased from 20% to 80%,the density of the specimens decrease from2.12 g/cm3 to 1.38 g/cm3, the porosity reduced from 32.5% to 16.7%,the compressive strengthreduced slightly from 1.82 MPa,then increased to 3.74 MPa,the tensile strength increasedfrom 0.22 MPa to 1.35 MPa.