DOI QR코드

DOI QR Code

Hardness and microstructural changes by cooling rate and holding time during porcelain firing of a multi-purpose dental gold alloy

다목적용 치과용 금합금의 소성 시 냉각속도와 계류시간에 따른 경도와 미세구조의 변화

  • Cho, Mi-Hyang (Dept. of Dental Lab, Wonkwang Health Science University)
  • 조미향 (원광보건대학교 치기공과)
  • Received : 2011.10.21
  • Accepted : 2011.12.28
  • Published : 2011.12.30

Abstract

Purpose: The aim of this study is to investigate the changes in hardness and microstructure of a dental multipurpose alloy after simulated complete firing with controlled cooling rate and holding time by characterizing the changes in hardness and microstructure after simulated firing with various cooling rates and holding times. Methods: Before hardness testing, the specimens were solution treated and then were rapidly quenched into ice brine. The specimens were completely fired in furnace. Hardness measurements were made using a Vickers microhardness tester. The specimens were examined at 15 kV using a field emission scanning electron microscope. Results: The maximum hardness value was obtained at stage 0 after simulated firing with various cooling rates (quick cooling, stage 0, stage 1, stage 2, stage 3). By the repetitive firing, the hardness of the tested alloy decreased gradually. By holding the specimen at $500^{\circ}C$ for 10-20min after simulated firing, the hardness increased apparently. However, to hold the alloy for long periods of time in the relatively high temperature after simulated firing resulted in the formation of thick oxidation layer. The oxide film formed on the surface of the alloy after simulated complete firing with controlled cooling rate, which was mainly composed of O and Zn. Conclusion: It is reasonable to hold the alloy at $500^{\circ}C$ for 10-20min after complete firing in other to improve the final hardness of the alloy.

Keywords

References

  1. Bertolotti RL, Moffa JP. Creep rate of porcelain bonding alloys as a function of temperature. J Dent Res 59, 2062-2065, 1980. https://doi.org/10.1177/00220345800590120601
  2. Campbell SD, Pelletier LB. Thermal cyclic distortion of metal ceramics: Part II-Etiology. J Prosthet Dent 68, 284-289, 1992. https://doi.org/10.1016/0022-3913(92)90331-4
  3. Campbell SD, Sirakian A, Pelletier LB, Giordano RA. Effect of firing cycle and surface finishing on distortion of metal ceramic castings. J Prosthet Dent 74, 476-481, 1995. https://doi.org/10.1016/S0022-3913(05)80348-8
  4. Chew CL, Norman RD, Stewart GP. Mechanical properties of metal-ceramic alloys at high temperature. Dent Mater 6, 223-227, 1990. https://doi.org/10.1016/S0109-5641(05)80002-8
  5. Cho MH, Lim IS, Lee HK, Seol HJ, Kwon YH, Kim HI. Precipitation hardening of Cu-free dental gold alloy for multipurpose. J Korean Res Soc Dent Mater 37, 141-150, 2010.
  6. Fischer J, Baltzer N, Fleetwood PW. Thermal creep analysis of precious metal alloys for the ceramic-fused-to-metal technique. Dental materials 16, 109-113, 2000. https://doi.org/10.1016/S0109-5641(99)00086-X
  7. Hisatsune K, Nakagawa M, Udoh K, Sosrosoedirdjo BI, Hasaka M. Age-hardening reactions and microstructures of a dental gold alloy with palladium and platium. J Mater Sci Mater Med 1, 49-54, 1990. https://doi.org/10.1007/BF00705354
  8. Kawashima I, Ohno H, Sarkar NK. Effect of Pd or Au addition on age-hardening in AgMnbased alloys. Dent Mater 16, 75-79, 2000. https://doi.org/10.1016/S0109-5641(99)00092-5
  9. Kim HI, Kim YK, Jang MI, Hisatsune K, Sakrana AAELS. Age-hardening reactions in a type III dental gold alloy. Biomaterials 22, 1433- 1438, 2001. https://doi.org/10.1016/S0142-9612(00)00301-X
  10. Kim HI, Park YH, Lee HK, Seol HJ, Shiraishi T, Hisatsune K. Precipitation hardening in a dental low-gold alloy. Dent Mater 22, 11-20, 2003
  11. Liu WB, Wang JN. Strengthening of a Pd-free high gold dental alloy for porcelain bonding by a pre-firing heat treatment. Dental materials 23, 1136-1141, 2007. https://doi.org/10.1016/j.dental.2006.06.048
  12. Makoto Yamamoto. Metal-Ceramics 이론과 실제. 제 2판, 지성출판사, 15, 1999.
  13. Park JH, Cho MH, Park MG, Kwon YH, Kim HI, Seol HJ. Age-hardening by grain interior and grain boundary precipitation in an Au- Ag-Pt-Zn-In alloy for multipurpose dental use. Gold Bull 43, 316-323, 2010a. https://doi.org/10.1007/BF03215001
  14. Park MG. Age-hardening and related phase transformation in a dental Ag-Au-Cu-Pd alloy with a small zinc addition. J Korean Res Soc Dent Mater 37, 251-258, 2010b.
  15. Reed-Hill RE. Physical metallurgy principles, 2nd Van Nostrand Co, New, 361-362, 1973.
  16. Seol HJ, Lee GY, Cho MH, Cho SY, Kwon YH, Kim HI. Precipitation hardening in a silver-free PFM alloy of Pd-Sn-Zn-Ga system during porcelain firing prcess. J Korean Res Soc Dent Mater 2, 107-116, 2011a.
  17. Seol HJ, Shiraishi Y, Tanaka E, Miura K, Hisatsune K, Kim HI. Ordering behaviors and age-hardening in experimental AuCu- Zn pseudobinary alloys for dental applications. Biomaterials 23, 4873-4879, 2002. https://doi.org/10.1016/S0142-9612(02)00245-4
  18. Seol HJ, Sim JS, Cho MH, Park MG, Kwon YH, Kim HI. The hardness and microstructural changes by the cooling rate in a PFM gold alloy during the porcelain firing cycles. J Korean Res Soc Dent Mater 1, 65-74, 2011b.
  19. Seol HJ, Son HK, Yu CH, Kwon YH, Kim HI. Precipitation hardening of a Cu-free Au- Ag-Pd-In dental alloy. J Alloys Compd 402, 130-135, 2005. https://doi.org/10.1016/j.jallcom.2005.04.017
  20. Shim JY, Jang MI, Kim HI. The temperatures of heat treatment in a dental low-gold alloy. J Korean Res Soc Dent Mater 22, 21-27, 1995.
  21. Tanaka Y, Udoh K, Hisatsune K, Yasuda K. Early stage of ordering in stoichiometric AuCu alloy. Mater Trans JIM 39, 87-94, 1998. https://doi.org/10.2320/matertrans1989.39.87
  22. Wang JN, Liu WB. Pd-free high gold dental alloy for porcelain bonding. Gold Bull 39, 114-120, 2006. https://doi.org/10.1007/BF03215538
  23. Winn H, Tanaka Y, Shiraishi T, Udoh K, Miura E, Hernandez RI, Takuma Y, Hisatsune K. Coherent phase diagram of Au-Cu-Pd ternary system near and within the twophase region of Au3Cu and AuCu I ordered phases. J Alloys Compd 306, 262-269, 2000. https://doi.org/10.1016/S0925-8388(00)00791-X
  24. Winn H, Udoh K, Tanaka Y, Hernadez RI, Takuma K, Hisatsune K. Phase transformations and age-hardening behaviors related to Au3Cu in Au-Cu-Pd alloys. Dent Mater J 18, 218-234, 1999. https://doi.org/10.4012/dmj.18.218