KMID : 1035320150420030207
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Korean Society for Dental Materials 2015 Volume.42 No. 3 p.207 ~ p.215
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Effect of cooling rate after oxidation on hardness changes by firing simulation of Pd-Cu-Ga-In metal-ceramic alloy
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Shin Hye-Jung
Yu Young-Jun Kwon Yong-Hoon Kim Hyung-Il Seol Hyo-Joung
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Abstract
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Effect of cooling rate after oxidation on hardness changes by firing simulation of Pd-Cu-Ga-In metal-ceramic alloy was examined by observing the change in hardness, crystal structure and microstructure. The hardness of specimen which was softened by ice quenching after oxidation increased apparently and such a high hardness was maintained during the subsequent firing stages. The hardness of specimen cooled at stage 0 after oxidation increased slighty and then the hardness decreased by wash treatment which is the first firing stage. Thereafter the low hardness was maintained during the subsequent firing stages. Specimen which was cooled by ice quenching after oxidation was softened due to homogenization of the microstructure, and then it was hardened due to precipitation during the simulated firing stages. In the specimens cooled at stage 0 or ice quenched after oxidation, Pd content was lower and Cu and Ga content was higher in precipitates than in the matrix. From the above results, cooling rate after oxidation did not affect the hardness changes of the metal substructure by firing simulation of Pd-Cu-Ga-In metal-ceramic alloy. Specimen which was ice quenched after oxidation was softened, which made processing easy.
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KEYWORD
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Pd-Cu-Ga-In metal-ceramic alloy, Firing simulation, Precipitation harding, Cooling rate, Microstructure
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