title: Heat treatment effects on electrochemical corrosion parameters of high-Pd alloys.
abstract: This research determined the effect oxidation, as that occurs during porcelain firing, has upon the corrosion parameters of Pd-based ceramic alloys and how it may relate to Pd allergy. The 20 h open circuit potential (OCP), 20 h corrosion rate (Icorr), and anodic polarization (E-i) curves of 11 commercial Pd alloys were measured in a phosphate buffered saline solution. The alloys were divided into the following four groups based upon composition: PdGa(Ag), PdCu, PdAg, and AuPd and tested in both as-cast and oxidized conditions. In both the as-cast and oxidized conditions, the OCP of Ag-containing Pd alloys is significantly lower than non Ag-containing high-Pd alloys. The OCP of all alloys increased after oxidation. With regard to corrosion rate, the Ag-containing alloys showed a decrease in Icorr with oxidation. In contrast, three of the four non Ag-containing high-Pd (>or=74 wt%) alloys exhibited a higher Icorr. A comparison of the anodic polarization curves showed only the alloys containing larger amounts (>or=16 wt%) of Ag displayed a notable difference between as-cast and oxidized states. Oxidation as required during porcelain-fused-to-metal device preparation alters the electrochemical characteristics of the alloys studied. This alteration may be of importance with regard to their potential for Pd allergy.
authors.affiliation: Dental Biomaterials, School of Dentistry, Marquette University, 113A Wehr Physics Building, Milwaukee, WI 53201-1881, USA. david.berzins@marquette.edu
authors.forename: D W
authors.initials: DW
authors.lastname: Berzins
authors.forename: I
authors.initials: I
authors.lastname: Kawashima
authors.forename: R
authors.initials: R
authors.lastname: Graves
authors.forename: N K
authors.initials: NK
authors.lastname: Sarkar
mesh_terms: D000497:Alloys; D002516:Ceramics / Q000737:chemistry; D003300:Copper / Q000737:chemistry; D003722:Dental Alloys; D004563:Electrochemistry / Q000379:methods*; D006358:Hot Temperature; D008422:Materials Testing; D016876:Metal Ceramic Alloys / Q000737:chemistry; D008670:Metals / Q000737:chemistry; D010087:Oxides / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D010165:Palladium / Q000737:chemistry*; D011199:Potentiometry / Q000379:methods; D012834:Silver / Q000737:chemistry; D013696:Temperature
chemical_list: D000497:Alloys; D003722:Dental Alloys; D016876:Metal Ceramic Alloys; D008670:Metals; D010087:Oxides; D012834:Silver; D010165:Palladium; D003300:Copper; D010100:Oxygen