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KMID : 0362220130400030185
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Journal of The Korean Research Society for Dental Materials
2013 Volume.40 No. 3 p.185 ~ p.194
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Hardness Change by Simulated Firing Condition in an Ag-Pd-In Metal-ceramic Alloy
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Jeon Byung-Wook
Lee Gwang-Young
Kwon Yong-Hoon
Kim Hyung-Il
Seol Hyo-Joung
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Abstract
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Hardness change by simulated complete firing cycle and holding condition in an Ag-Pd-In metalceramic alloy was elucidated by characterizing the changes in hardness, microstructure and crystal structure after simulated complete firing with various cooling rates (ice quenching, quick cooling, stages 0, 1, 2 and 3) and holding conditions to identify the most effective condition for practical use. The maximum hardness value was obtained at stage 0 after simulated firing. And the most effective starting temperature for firing was 550 ℃. The Vickers hardness value of the solution-treated specimen increased from 185 (Hv) to 254 (Hv) by degassing treatment. The hardness increase in the degassing stage of the simulated firing seemed to be caused by the lattice distortion which is related to the precipitation in the alloy. After that, by the repetitive firing, the hardness value of the tested alloy decreased gradually, resulting in a softening effect. By holding the specimen at 450-600 ℃ after simulated firing, the hardness increased apparently. The most effective holding condition were obtained at 600 ℃ for 15 min. Therefore, holding treatment at 600 ℃ for 15 min after simulated complete firing is recommended to improve hardness of the Ag-Pd-In metal-ceramic alloy.
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KEYWORD
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Simulated firing cycle, cooling rate, metal-ceramic alloy, Ag-Pd-In
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