Mechanical properties of materials for spectacle lens cutting(I)

안경렌즈 절삭용 재료의 기계적 특성(I)

  • Lee, Young-Il (Department of Ophthalmic Optics, Dongnam Health College) ;
  • Kim, Jin-Koo (Department of Ophthalmic Optics, Dongnam Health College)
  • 이영일 (동남보건대학 안경광학과) ;
  • 김진구 (동남보건대학 안경광학과)
  • Published : 2000.06.30

Abstract

In this study, materials for spectacle lens cutting were fabricated by hot-pressing and annealing SiC powders with $Al_2O_3$ and $Y_2O_3$. A microstructure that consisted of uniformly distributed, large SiC grains and elongated SiC grains was developed by using ${\alpha}$-SiC powders. The microstructure was observed by scanning electron microscope(SEM). By hot-pressing and subsequent annealing, elongated ${\beta}$-SiC grains were grown via ${\beta}{\rightarrow}{\alpha}$ phase. This is caused the crack deflection as toughening mechanism. Typical hardness and fracture toughness of materials for spectacle lens cutting were 13.3 GPa and $4.8MPa{\cdot}m^{1/2}$, respectively.

본 연구에서는 ${\beta}$-SiC, ${\alpha}$-SiC, $Al_2O_3$, $Y_2O_3$ 분말들을 출발원료로 사용하여 일축 가압 소결 및 열처리함으로서 길게 자란 탄화규소입가들이 균일하게 분포된 자기강화 미세구조를 갖는 안경렌즈 절삭용 재료를 제조하였다. 주사전자 현미경을 통해 미세구조를 관찰하였다. 가압 소결과 열처리 동안에 탄화규소의 ${\beta}{\rightarrow}{\alpha}$ 상변태에 기인하여 길게 자란 ${\alpha}$-SiC 입자들이 형성되었고, 이로 인해 파괴인성이 증가하였다. 신소재의 대표적인 경도와 파괴인성은 각각 13.3 GPa과 $4.8MPa{\cdot}m^{1/2}$이었다.

Keywords