MELT-INFILTRATION PROCESSING AND FRACTURE-TOUGHNESS OF ALUMINA-GLASS DENTAL COMPOSITES

Alumina-glass composites were prepared by a melt-infiltration process that is similar to a fabrication method for dental crowns and bridges. Cylindrical alumina samples with green densities ranging from 62% to 72% of theoretical were formed by slip casting followed by sintering a t 1100-degrees-C for 2 h. A borosilicate glass was infiltrated at 1200 -degrees-C, resulting in a composite microstructure consisting of fuse d alumina particles and glass-filled pores. Fracture toughness of the composites, measured by a chevron-notch method with a short rod sample , was approximately 3.8 MPa.m1/2 and was relatively insensitive to the volume fraction of alumina in the range of 0.62 to 0.72.