The effect of recasting on microstructure of dental ceramic alloys

PURPOSE To investigate the effects of recasting on metallographic microstructure of cobalt-chromium(Co-Cr), commercially pure titanium(cpTi), palladium-copper-gallium(Pd-Cu-Ga), aurum-platinum(Au-Pt) ceramic alloys. METHODS Without adding new alloys, Co-Cr, cpTi, Pd-Cu-Ga and Au-Pt ceramic alloys were recasted for 1-3 times under the circumstance of vacuum compressive casting with argon. Before each recasting, these 4 ceramic alloys casted previously were treated by the most appropriate way which has been reported by our previous study. According to GB/T13298-2015 standards, the specimens of 4 ceramic alloys after recasting 1-3 times were grinded, polished, and etched and then the metallographic microstructure of them were determined by a metallographic microscope or scanning electron microscopy(SEM). RESULTS With the increase of recasting times, the microstructure of Co-Cr ceramic alloy showed grain growth, grain matrix increase, and the intermetallic compound in the grain boundary increase, the microstructure of the cpTi ceramic alloy showed grain growth. The samples of cpTi ceramic alloy recasting twice appeared shaft tendency, and the ones which were recasted 3 times were compound of α-phase and β-phase. The microstructure of the Pd-Cu-Ga ceramic alloy showed grain growth slightly after casting 2-3 times, while no significant change was found on the microstructure of the Au-Pt ceramic alloy. CONCLUSIONS Recasting changes the microstructure of Co-Cr, cpTi, and Pd-Cu-Ga ceramic alloys, and the ceramic alloys may recycled by the manufacturers.