Journal of the Korean Crystal Growth and Crystal Technology (한국결정성장학회지)

The Korea Association of Crystal Growth (한국결정성장학회)
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Effects of $Y_2O_3$ addition and sintering time on denazification and thermal conductivity of AlN ceramics during hot-press sintering

$Y_2O_3$ 첨가와 소결 시간이 AlN 세라믹스의 일축 가압 소결 거동 및 열전도도에 미치는 영향

  • Chae, Jae-Hong (Korea Institute of Ceramic Engineering and Technology) ;
  • Park, Joo-Seok (Korea Institute of Ceramic Engineering and Technology) ;
  • Ahn, Jong-Pil (Korea Institute of Ceramic Engineering and Technology) ;
  • Kim, Kyoung-Hun (Korea Institute of Ceramic Engineering and Technology) ;
  • Lee, Byung-Ha (Department of Materials Science and Engineering, Myongji University)
  • Published : 2008.12.31
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Abstract

Hot-press sintering of AlN ceramics were carried out with $Y_2O_3$ as sintering additive at a sintering temperature $1,750{\sim}1,850^{\circ}C$. The effect of $Y_2O_3$ addition and sintering time on sintering behavior and thermal conductivity of AlN ceramics was investigated. $Y_2O_3$ added AlN showed noticeably higher denazification rate than pure AlN. The thermal conductivity of AlN specimens was promoted by the addition of $Y_2O_3$ in spite of the formation of YAG secondary phase in AlN grain boundaries and grain boundary triple junction because $Y_2O_3$ addition could reduced the oxygen contents in AlN lattice which is primary factor of thermal conductivity. Typically, the thermal conductivity of 5 wt% $Y_2O_3$ added specimen was dramatically improved by the increase of sintering time because the elimination of YAG secondary phases from the grain boundary due to the evaporation, as well as the grain-growth of AlN grains.

AlN 소결체를 제조함에 있어서 $Y_2O_3$를 소결 첨가제로 하여 일축 가압 소결법을 적용하여 소결 조제 첨가량의 변화와 소결 시간의 변화에 따른 소결 특성, 미세구조 및 열전도도 측성에 대하여 조사하였다. $Y_2O_3$의 첨가로 인하여 AlN의 치밀화가 첨가하지 않은 경우보다 증진됨을 확인할 수 있었으며, 결정립계 및 결정립계 삼중점에서 YAG 이차상을 형성함으로써 AlN 결정 격자 내의 산소 결함 농도를 낮춰 열전도도를 향상시킴을 알 수 있었다. 특히, 소결 시간을 증대함에 따라 결정립 성장 및 열전도도의 방해 요소인 YAG 이차상이 고온에서 휘발됨에 따라 열전도도가 크게 향상됨을 확인할 수 있었다.

Keywords

References

  1. G.A. Slack, "Nonmetallic crystals with high thermal conductivity", J. Phys. Chem. Solids 34 (1973) 321 https://doi.org/10.1016/0022-3697(73)90092-9
  2. L.M. Sheppard, "Aluminum nitride: a versatile but challenging material", Am. Ceram. Soc. Bull. 69 (1990) 1801
  3. Y. Baik and R.A. Drew, "Aluminum nitride: processing and applications", Key Eng. Mater. 122-124 (1996) 553
  4. M. Kasori and F. Ueno, "Thermal conductivity improvement of YAG added AlN ceramics in the grain boundary elimination process", J. Euro. Ceram. Soc. 15 (1995) 435 https://doi.org/10.1016/0955-2219(95)91432-N
  5. K. Watari, K. Ishizaki and T. Fujikawa, "Thermal conduction mechanism of aluminium niride ceramics", J. Mater. Sci. 27 (1992) 2627 https://doi.org/10.1007/BF00540680
  6. K. Komeya, H. Inoue and A. Tsuge, "Effect of various additives on sintering of aluminum nitride", Yogyo-Kyokaishi 93 (1985) 41
  7. K. Komeya, H. Inoue and A. Tsuge, "Role of $Y_2O_3$ and $SiO_2$ additions in sintering of AlN", J. Am. Ceram. Soc. 54 (1974) 411
  8. A.V. Virkar, T.B. Jackson and R.A. Cutler, "Thermodynamic and kinetic effects of oxygen removal on the thermal conductivity of aluminum nitride", J. Am. Ceram. Soc. 72 (1989) 2031 https://doi.org/10.1111/j.1151-2916.1989.tb06027.x
  9. T.B. Jackson, A.V. Virkar, K.L. More, R.B. Dinwideie and R.A. Cutler, "High thermal conductivity aluminum nitride ceramics: the effect of thermodynamic, kinetic and microstructural factors", J. Am. Ceram. Soc. 80 (1997) 1421 https://doi.org/10.1111/j.1151-2916.1997.tb03000.x
  10. G. Pezzotti, A. Nakahira and M. Tajika, "Effect of extended annealing cycles on the thermal conductivity of AlN/$Y_2O_3$ ceramics", J. Euro. Ceram. Soc. 20 (2000) 1319 https://doi.org/10.1016/S0955-2219(99)00286-1
  11. L. Qiao, H. Zhou, H. Xue and S. Wang, "Effect of $Y_2O_3$ on low temperature sintering and thermal conductivity of AlN ceramics", J. Euro. Ceram. Soc. 23 (2003) 61 https://doi.org/10.1016/S0955-2219(02)00079-1
  12. S. Mitra, G. Dutta and I. Dutta, "Effect of heat treatment on the microstructure and properties of dense AlN sintered with $Y_2O_3$ additions", J. Am. Ceram. Soc. 78[9] (1995) 2335 https://doi.org/10.1111/j.1151-2916.1995.tb08666.x
  13. P.H. Klein and W.J. Croft, "Thermal conductivity, diffusivity, and expansion of $Y_2O_3$, $Y_3Al_5O_{12}$ and $LaF_3$ in the range of 77-300 K", J. Appl. Phys. 38 (1967) 1603 https://doi.org/10.1063/1.1709730
  14. Y.D. Yu, A.M. Hundere, R. Hoier, R.E. Dunin- Borkowski and M.A. Einarsrud, "Microstructural characterization and microstructural effects on the thermal conductivity of AlN($Y_2O_3$) ceramics", J. Euro. Ceram. Soc. 22 (2002) 247 https://doi.org/10.1016/S0955-2219(01)00252-7