포세린 소성시 냉각속도에 따른 PFM용 금합금의 경도와 미세구조의 변화
The Hardness and Microstructural Changes by the Cooling Rate in a PFM Gold Alloy during the Porcelain Firing Cycles
설효정, 심재성, 조미향, 박미경, 권용훈, 김형일,
소속 상세정보
설효정 ( Seol Hyo-Joung ) - 부산대학교 치의학전문대학원 치과재료학교실
심재성 ( Sim Jae-Seong ) - 부산대학교 치의학전문대학원 치과재료학교실
조미향 ( Cho Mi-Hyang ) - 원광보건대학 치기공과
박미경 ( Park Mi-Gyoung ) - 부산가톨릭대학교 보건대학 치기공학과
권용훈 ( Kwon Yong-Hoon ) - 부산대학교 치의학전문대학원 치과재료학교실
김형일 ( Kim Hyung-Il ) - 부산대학교 치의학전문대학원 치과재료학교실
KMID : 0362220110380010065
Abstract
The hardness and microstructural changes by cooling rate in a Pd-free Au-Pt-Zn alloy containing minor ingredients during firing cycles were elucidated by characterizing the age-hardening behavior and age-hardenability, phase transformation and microstructural changes during aging process, changes in hardness after simulated firing with various cooling rates, changes in hardness and microstructure after simulated complete firing with controlled cooling rate. The age-hard ening and softening mechanisms of a Pd-free Au-Pt-Zn alloy were homogeneous grain-interior precipitation of the Pt-rich phase and the subsequent lamellar-forming grain boundary reaction, respectively. The lamellar structure was composed of the Pt-depleted Au-rich α1’ matrix l ayer and the Pt-rich α3 precipitate l ayer, and the growth of l amellar structure was directly connected with the decrease in hardness. The maximum hardness value was obtained at stage 1 after simulated firing with various cooling rates (ice quenching, quick cooling, stage 0, stage 1, stage 2, stage 3). After simulated complete firing with controlled cooling rate (stage 1), the hardness value of t he s olution-treated specimen increased apparently f rom 89.3 (Hv) t o 170 (Hv) without a pparent lamellar-forming grain boundary reaction. It is advisable to control the cooling rate in the final firing stage of the complete firing cycles.
키워드
Age-hardening and softening mechanism; Cooling rate; Gold-platinum PFM alloy; Grain-boundary reaction; Grain-interior precipitation
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