Biomaterial Database

Tarnish and corrosion of a commercial dental Ag-Pd-Cu-Au casting alloy. 1984

L Niemi, and R I Holland

The correlation between microstructure, tarnish, and corrosion behavior of a commercial dental Ag-Pd-Cu-Au casting alloy after various heat treatments was studied. The attacked structural components were identified by comparing SEM micrographs with light optical micrographs taken after exposure of the alloy to a 2% Na2S solution and after dynamic polarization in de-aerated artificial saliva. The characteristic dynamic polarization curves for the alloy after the heat treatments were established. The results were verified by analogous testing of two experimental alloys with compositions similar to those of the analyzed components in the commercial alloy annealed at 600 degrees C for seven wk. The matrix of the commercial alloy was decomposed, according to the heat treatments, into varying proportions of a tarnish- and corrosion-resistant Cu- and Pd-rich component (A) and a nonresistant Ag-rich component (B). The presence of A considerably increased the tarnish rate of B, due to galvanic coupling. Age-hardening of the alloy increased the proportion of the tarnish- and corrosion-prone component B.

UI	MeSH Term	Description	Entries
D008855	Microscopy, Electron, Scanning	Microscopy in which the object is examined directly by an electron beam scanning the specimen point-by-point. The image is constructed by detecting the products of specimen interactions that are projected above the plane of the sample, such as backscattered electrons. Although SCANNING TRANSMISSION ELECTRON MICROSCOPY also scans the specimen point by point with the electron beam, the image is constructed by detecting the electrons, or their interaction products that are transmitted through the sample plane, so that is a form of TRANSMISSION ELECTRON MICROSCOPY.	Scanning Electron Microscopy,Electron Scanning Microscopy,Electron Microscopies, Scanning,Electron Microscopy, Scanning,Electron Scanning Microscopies,Microscopies, Electron Scanning,Microscopies, Scanning Electron,Microscopy, Electron Scanning,Microscopy, Scanning Electron,Scanning Electron Microscopies,Scanning Microscopies, Electron,Scanning Microscopy, Electron
D010165	Palladium	A chemical element having an atomic weight of 106.4, atomic number of 46, and the symbol Pd. It is a white, ductile metal resembling platinum, and following it in abundance and importance of applications. It is used in dentistry in the form of gold, silver, and copper alloys.
D002627	Chemistry, Physical	The study of CHEMICAL PHENOMENA and processes in terms of the underlying PHYSICAL PHENOMENA and processes.	Physical Chemistry,Chemistries, Physical,Physical Chemistries
D003116	Color	The visually perceived property of objects created by absorption or reflection of specific wavelengths of light.	Colors
D003300	Copper	A heavy metal trace element with the atomic symbol Cu, atomic number 29, and atomic weight 63.55.	Copper-63,Copper 63
D003343	Corrosion	The gradual destruction of a metal or alloy due to oxidation or action of a chemical agent. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Corrosions
D004572	Electrolysis	Destruction by passage of a galvanic electric current, as in disintegration of a chemical compound in solution.	Electrolyses
D006047	Gold Alloys	Alloys that contain a high percentage of gold. They are used in restorative or prosthetic dentistry.	Gold Alloy,Alloy, Gold,Alloys, Gold
D006358	Hot Temperature	Presence of warmth or heat or a temperature notably higher than an accustomed norm.	Heat,Hot Temperatures,Temperature, Hot,Temperatures, Hot
D012464	Saliva, Artificial	A solution used for irrigating the mouth in xerostomia and as a substitute for saliva.	Artificial Saliva