title: Corrosion behavior of palladium-silver-copper alloys in model saliva.
abstract: OBJECTIVE
  Palladium-silver system alloyed with other metals represents one of possible material choices in prosthetics. Its corrosion properties are influenced by minority components added in order to obtain the properties required for stomatological purposes. The objective of this work was to ascertain the influence of copper on the corrosion mechanism of palladium-silver alloys.
  
  
  METHODS
  Corrosion properties of four palladium-silver-copper alloys were compared with the behavior of the palladium-silver binary system. Standard electrochemical measurements in a model saliva solution were complemented with an XPS analysis of the specimens surface. Experimental data were compared with the results of thermodynamic analysis.
  
  
  RESULTS
  The foregoing study revealed formation of a saline layer of insoluble silver compounds as the dominant feature of the corrosion mechanism in a binary system. This process is suppressed in ternary alloys where electrochemical reactions of copper take place on the alloy-electrolyte phase boundary leading to the formation of a layer based on copper oxides.
  
  
  CONCLUSIONS
  The alloying of the palladium-silver binary system with copper results in an important change in the corrosion behavior of ternary alloys. A change in the mechanism of interaction with the environment leads to susceptibility to non-uniform corrosion.
authors.affiliation: Institute of Chemical Technology, Department of Metals and Corrosion Engineering, Technicka 5, 166 28 Prague 6, Czech Republic. Ludek.Joska@vscht.cz
authors.forename: Ludek
authors.initials: L
authors.lastname: Joska
authors.forename: Marcela
authors.initials: M
authors.lastname: Poddana
authors.forename: Jindrich
authors.initials: J
authors.lastname: Leitner
mesh_terms: D003300:Copper / Q000737:chemistry*; D003343:Corrosion; D003722:Dental Alloys / Q000737:chemistry*; D004563:Electrochemistry; D004577:Electron Probe Microanalysis; D006801:Humans; D008422:Materials Testing; D010165:Palladium / Q000737:chemistry*; D011199:Potentiometry; D012464:Saliva, Artificial / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D013499:Surface Properties; D013816:Thermodynamics; D013997:Time Factors
chemical_list: D003722:Dental Alloys; D012464:Saliva, Artificial; D012834:Silver; D010165:Palladium; D003300:Copper; C030973:cupric oxide