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Effect of palladium addition on the tarnishing of dental gold alloys

  • M. Ohta
  • M. Nakagawa
  • S. Matsuya
Papers

Abstract

Tarnishing tests were carried out on Au-Cu-Ag and Au-Cu-Pd alloys. This study focused on the individual and combined effects of nobility, palladium content and microstructure. Tarnish resistance was almost perfect for the alloys with nobility higher than 50 at%, but it seemed to relate to the palladium : gold atomic ratio for the alloys with low nobility. Palladium inclusion reduced the tarnish susceptibility up to about 10 at%. This decrease in the degree of tarnishing was attributed to the decrease in the diffusion rate of S2 ion which resulted in a decrease in the growth rate of sulphide layer. Tarnishing of the alloy with low nobility was very sensitive to its microstructure. The tarnishing susceptibility of dual-phase Au-Cu-Ag alloy was twice as high as that of the single-phase alloy. However, palladium-bearing alloy showed no increase in the degree of tarnishing by phase separation. This may be attributed to the enrichment of palladium in the copper-rich phase.

Keywords

Polymer Gold Microstructure Sulphide Palladium 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Chapman and Hall Ltd 1990

Authors and Affiliations

  • M. Ohta
    • 1
  • M. Nakagawa
    • 1
  • S. Matsuya
    • 1
  1. 1.Department of Dental Materials Engineering, School of DentistryKyushu UniversityFukuokaJapan

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