| In order to understand the effect of fabrication temperature, a computer controlled 3-D gantry system was used to extrude aqueous alumina paste using Extrusion Freeform Fabrication. The system includes a temperature control subsystem that allows for fabrication of components below the paste's freezing temperature in the range of -10°C to -30°C and a hot plate with temperature in the range of 20°C to 80°C inside a room temperature chamber. Comparisons in terms of relative density, mechanical properties, part accuracy and minimum deposition angle were performed by Extrusion Freeform Fabrication at 40°C plate temperature inside a room temperature chamber and at -20°C plate temperature with a -20°C chamber temperature.;The parts fabricated at 40°C were able to achieve relative density, Young's modulus and flexure strength as high as 96.73%, 311 GPa, and 338 MPa, respectively; the minimum deposition angle achieved was 50o at 38 mm bottom diameter and the parts had 7-14% shrinkage after sintering. In comparison, for the parts fabricated at -20°C, the average relative density, Young's modulus and flexure strength obtained were 91.55%, 280 GPa, and 300 MPa, respectively; parts could be fabricated with a 24o minimum deposition angle at 64 mm bottom diameter and had 10-16% shrinkage after sintering. The hardnesses of parts fabricated at 40°C and fabricated at -20°C were 16.78 GPa and 14.36 GPa, respectively. Microstructures were studied by using SEM to obtain a deeper understanding of the fabrication temperature effect. |
