title: Development of casting investment preventing blackening of noble metal alloys part 1. Application of developed investment for Ag-Pd-Cu-Au alloy.
abstract: The objective of this study is to develop a casting investment that prevents the blackening of the cast surface of noble metal alloys. The experimental investments were prepared using a gypsum-bonded investment in which the metallic powders such as boron (B), silicon (Si), aluminum (Al) and titanium (Ti) were added as oxidizing agents. An Ag-Pd-Cu-Au alloy was cast into the mold made of the prepared investment. The effect of the addition of each metal powder was evaluated from the color difference between the as-cast surface and the polished surface of the cast specimen. The color of the as-cast surface approached that of the polished surface with increasing B and Al content. A lower mean value in the color difference was obtained at 0.25-1.00 mass% B content. B and Al are useful as an additive in a gypsum-bonded investment to prevent the blackening of an Ag-Pd-Cu-Au alloy. The effects of Si and Ti powder addition could not be found.
authors.affiliation: Department of Dental Materials Science, School of Dentistry at Niigata, The Nippon Dental University 1-8 Hamaura-cho, Niigata City, Niigata, 951-8580, Japan.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Kakuta
authors.forename: Akira
authors.initials: A
authors.lastname: Nakai
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Goto
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Wakamatsu
authors.forename: Atushi
authors.initials: A
authors.lastname: Yara
authors.forename: Yukio
authors.initials: Y
authors.lastname: Miyagawa
authors.forename: Hideo
authors.initials: H
authors.lastname: Ogura
mesh_terms: D000535:Aluminum / Q000737:chemistry; D001895:Boron / Q000737:chemistry; D002133:Calcium Sulfate / Q000737:chemistry*; D003116:Color; D003722:Dental Alloys / Q000737:chemistry*; D003734:Dental Casting Investment / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry; D019163:Reducing Agents / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry; D014025:Titanium / Q000737:chemistry
chemical_list: D003722:Dental Alloys; D003734:Dental Casting Investment; D010087:Oxides; D019163:Reducing Agents; D000535:Aluminum; D014025:Titanium; D001895:Boron; D002133:Calcium Sulfate; D012825:Silicon