| 졸-겔법으로 제조한 $ZrO_2.SiO_2$계 결정화유리의 결정화 및 파괴인성에 관한 연구 |
| 신대용, 한상목1, 강위수2 |
강원대학교 석재복합 신소재제품 연구센터
1강원대학교 신소재공학과
2강원대학교 농업기계공학전공 |
| A Study of Crystallization and Fracture Toughness of Glass Ceramics in the $ZrO_2.SiO_2$ Systems Prepared by the Sol-Gel Method |
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| ABSTRACT |
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Precursor gels with the composition of xZrO2·(100-x)SiO2 systems (x=10, 20 and 30 mol%) were prepared by the sol-gel method. Kinetic parameters, such as activation energy, Avrami's exponent, n, and dimensionality crystal growth value, m, have been simultaneously calculated from the DTA data using Kissinger and Matusita equations. The crystallite size dependence of tetragonal to monoclinic transformation of ZrO2 was investigated using XRD, in relation to the fracture toughness. The crystallization of tetragonal ZrO2 occurred through 3-dimensional diffusiion controlled growth(n=m=2) and the activation energy for crystallization was calculated using Kissinger and Matusita equations, as about 310∼325±10kJ/mol. The growth of t-ZrO2, in proportion to the cube of radius, increased with increasing heating temperature and hteat-treatment time. It was suggested that the diffusion of Zr4+ ions by Ostwald ripening was rate-limiting process for thegrowth of t-ZrO2 crystallite size. The fracture toughness of xZrO2·(100-x)SiO2 systems glass ceramics increased with increasing crystallite size of t-ZrO2. The fracture toughness of 30ZrO2·70SiO2 system glass ceramics heated at 1,100℃ for 5h was 4.84 MPam1/2 at a critical crystaliite size of 40 nm. |
| Key words:
Glass ceramics, Crystallization kinetics, DTA, Tetragonal ZrO2, Monoclinic ZrO2 |
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