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KMID : 1035320150420020165
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Korean Society for Dental Materials
2015 Volume.42 No. 2 p.165 ~ p.171
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Precipitation hardening by holding after simulated complete firing in a Pd-Ag-Au-In-Sn metal-ceramic alloy
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Cho Mi-Hyang
Cho Su-Yoen
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Abstract
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The aim of present study is to evaluate the changes in hardness of a Pd(Palladium)-Ag(Silver)-Au(Gold)-In(Indium)-Sn(Tin) metal- ceramic alloy by holding after simulated complete firing. In the porcelain firing simulated specimen, the hardness increased by holding at 500~700 ℃. The most effective holding condition for hardening of the Pd-Ag-Au-In-Sn alloy was the holding at 700 ℃ for 10 min. In all specimens, the microstructure was composed of the matrix covered with precipitates and the particle-like structure. The increase in hardness was resulted from the precipitation of the Pd3(In,Sn,Ga) phase with f.c.t. structure in the matrix composed of the Pd-Ag-based phase with f.c.c. structure. The decrease in hardness by prolonged holding up to 50 min at 700 ℃ was resulted from the microstructural coarsening of the precipitates. In the Pd-Ag-Au-In-Sn metal-ceramic alloy, the holding at 700 ℃ for 10 min after simulated complete firing is an effective method for improving hardness without affecting the porcelain superstructure, therefore it is recommended for clinical application.
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KEYWORD
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Pd-Ag-Au-In-Sn alloy, holding, precipitation, coarsening
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