치과용 비귀금속 합금의 열처리에 따른 미세조직 및 기계적 성질의 변화

Abstract

The purpose of this study was to evaluate the effect of various heat-treatments on mechanical properties of dental base metal alloys. Three commercial dental base metal alloys (Top crown: TC, Top partial: TP, ceramic: TE) were used. Thirty specimens for the tensile strength test (dog-bone type) were cast with lost wax technique. After casting, specimens were bench-cooled for 1 hour before they were removed from the investment. The specimens were classified into three groups; 1) As cast (TC, TP, TE) : bench cooling after casting, 2) Heat treatment (TC, TP) : solution heat treatment (1100℃ for 1 hour and quenching) following Age hardening (aging at 650℃ for 10 min. and furnace cooling), 3) Simulated porcelain firing heat treatment (TE). Each group comprised of five specimens for each material. Mechanical properties include tensile strength, elongation, elastic modulus, and micro-hardness. Microstructure was evaluated with metallic microscope. Results indicated that the heat treatments had little effect on the tensile strength, elongation, and microhardness of the dental base metal alloys, except the elastic modulus of TC and TP, which were increased significantly by heat treatment. It means that appropriate heat treatment can be expected to enhance the homogenization of microstructure of the base metal alloys without changing of mechanical properties, resulting in the improvement of corrosion resistance.