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Bending Strength Properties of SiC Ceramics at Different Roughness Values of Polishing Plates

연마판의 거칠기에 따르는 SiC 세라믹스의 굽힘강도 특성

  • Nam, Ki-Woo (Dept. of Materials Science and Engineering, Pukyong Nat'l Univ.) ;
  • Kim, Eun-Sun (Dept. of UR Interdisciplinary program of Mechanical Engineering, Graduate School, Pukyong Nat'l Univ.)
  • 남기우 (부경대학교 신소재공학부) ;
  • 김은선 (부경대학교 학연협동기계공학과)
  • Received : 2011.01.14
  • Accepted : 2011.04.04
  • Published : 2011.07.01

Abstract

This study was carried out on the crack healing of three types of SiC ceramics based on a $SiO_2$ additive, taking into account the roughness of the polishing plate used for polishing the specimens. The mixtures were subsequently hot-pressed in $N_2$ gas for one hour under 35 MPa at 2053 K. In these specimens, the optimized crack-healing condition was 1373 K for one hour in air. The crack-healing material of the cracked part was the glassy phase of $SiO_2$ that was formed by the oxidation of SiC. In the optimum healing condition, the bending strength of non-polished SiC ceramics was not completely recovered. However, the bending strength of the SAY specimen was excellent, considering the economic aspects of SAY, SAYS-1, and SAYS-2. The SAY specimen is definitely superior to the others after an hour of heat treatment. There was a decrease in the number and size of defects in the specimen polished by using a $125-{\mu}m$ polishing plate; however, the micro-surface defects were not completely repaired. The specimen polished by using a 40-${\mu}m$ polishing plate showed little voids or surface defects after an hour of heat treatment. The bending strength of the specimen mirror-polished by using a 6-${\mu}m$ polishing plate was completely recovered.

Keywords

SiC Ceramics;Bending Strength;Surface Grinding;Sintering Additive;Roughness of Polishing Plate

References

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