Three-Dimensional Printing of Complex-Shaped Alumina/Glass Composites

Alumina/glass composites were fabricated by three-dimensional printing (3DP (TM)) and pressureless infiltration of lanthanum-alumino-silicate glass Into sintered porous alumina preforms. The preforms were printed using an alumina/dextrin powder blend as a precursor material. They were sintered at 1600 degrees C for 2 h prior to glass infiltration at 1100 degrees C for 2 h. The influence of layer thickness and sample orientation within the building chamber of the 3D-printer on microstructure, porosity, and mechanical properties of the preforms and final. composites was investigated. The increase of the layer thickness from 90 to 150 mu m resulted in an increase of the total porosity from similar to 19 to similar to 39 vol% and thus, in a decrease of the mechanical properties of the sintered preforms. Bending strength and elastic modulus of sintered preforms were found to attain significantly higher values for samples orientated along the Y-axis of the 3D-printer compared to those orientated along the X- or the Z-axis, respectively. Fabricated Al2O3/glass composites exhibit improved fracture toughness, bending strength, Young's modulus, and Vickers hardness tip to 3.6 MPa m(1/2), 175 MPa, 228 GPa, and 12 GPa, respectively. Prototypes were fabricated on the basis of computer tomography data and computer aided design data to show geometric capability of the process.