Sulfuration resistance of five experimental Ag-Pd-Au-Cu alloys with low Pd content of 10 or 12%.
Commercial Ag-based alloy (46Ag-20Pd-12Au-20Cu alloy) is widely used in Japan as a casting alloy. As opposed to the commercial composition, we prepared five experimental Ag-based alloys with reduced Pd content of 10 or 12%, increased Au content of 20 to 30%, and reduced Cu content of 12 to 20%. We then evaluated their sulfuration resistance by analyzing cast specimen surfaces dipped in 0.1% Na2S solution with SEM/EPMA, TF-XRD, and XPS. It became evident that all alloys were susceptible to sulfuration in the segregated Ag-rich Pd-poor phases. The degree and speed of sulfuration, however, differed among the six alloys examined. In particular, one experimental alloy (46Ag-10Pd-30Au-12Cu) possessed a sulfuration resistance equal or superior to that of commercial Ag-based alloy, while the other four experimental alloys were inferior in sulfuration resistance. Based on the results of this study, we concluded that our newly developed 46Ag-10Pd-30Au-12Cu alloy could be employed as a new sulfuration-resistant Ag-based casting alloy--which is especially useful if the price of Pd is skyrocketing again.
Saitoh
Setsuo
S
Department of Dental Materials Science and Technology, Iwate Medical University School of Dentistry, 1-3-27, Chuo-dori, Morioka, Iwate 020-8505, Japan. setsuos@iwate-med.ac.jp
Araki
Yoshima
Y
Taira
Masayuki
M
D003343:Corrosion; D003722:Dental Alloys / Q000737:chemistry*; D003735:Dental Casting Technique; D004577:Electron Probe Microanalysis; D006047:Gold Alloys / Q000737:chemistry*; D008669:Metallurgy; D010165:Palladium / Q000737:chemistry* / Q000191:economics; D013455:Sulfur / Q000032:analysis; D013499:Surface Properties; D014961:X-Ray Diffraction
C120982:Ag-Pd-Cu-Au alloy; D003722:Dental Alloys; D006047:Gold Alloys; D010165:Palladium; D013455:Sulfur