Effect of Microstructure on Evaluation of Fracture Toughness and Hardness of Cutting Tool Ceramics

절삭 공구용 세라믹의 소결조직에 따른 파괴인성과 경도의 평가

  • 안동길 (대한중석초경(주) 종합기술연구소) ;
  • 윤명진 (경일대학교 기계공학부)
  • Published : 2000.12.01

Abstract

Dense $Al_2$O$_3$-30%TiC and Si$_3$N$_4$ ceramic tool materials with various grain size were produced by sintering-HIP treatment and by gas-pressure sintering. The fracture toughness was measured by indentation fracture and indentation strength method for both ceramics with various grain size. The effect of the grain size on the fracture toughness was evaluated, and the correlation between fracture toughness and mechanical properties such as hardness, Young\`s modulus and flexural strength of these ceramic were also investigated. The highest fracture toughness of around 6.7 MPa.m(sup)1/2 was obtained in Si$_3$N$_4$ ceramics with grain size of 1.58${\mu}{\textrm}{m}$. With a larger grain size of $Al_2$O$_3$-30%TiC and Si$_3$N$_4$ ceramics, the fracture toughness was generally increased. The increased fracture toughness of these ceramic also improved the flexural strength although the hardness decreased considerably. Similar results were obtained in grain size and mechanical properties on both $Al_2$O$_3$-30%TiC and Si$_3$N$_4$ ceramic tool materials.

Keywords

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