Abstract
The purpose of this study was to investigate the effects of firing conditions onfracture toughness. Three commercially available porcelains for high functional gold alloys, Carrara (CA), Deguceram Gold (DE) and Duceragold (DU), were used. In experiment 1, fracture toughness was investigated under firing treatment of 1, 3, or 5 times and firing temperatures of 0, 20, and 40°C higher than the manufacturers' standard temperature (CA: 845°C, DE: 780°C, DU: 780°C). In experiment 2, the effects of the mooring procedure on fracture toughness was investigated.
The results were as follows:
1. No difference was observed among fracture toughness of firing times in CA and DU, but fracture toughness wasincreased in DE with repeated firing. The maximum value of fracture toughness was 1.96±0.5 MNm-3/2 in DU with firing treatment of three times and the standard temperature. The minimum value was 1.35±0.12 MNm-3/2 in DE with firing treatment of once and 20°C-higher temperature.
2. There was nodifference between fracture toughness in DE and DU before and after mooring.
