Abstract
To obtain basic information for improvement of the corrosion-resistant nature of dental Ag-Pd-Cu-Au alloy, its corrosion behavior, such as the electrochemical chage, surface structure change, corrosion product, and ion-release rate in a dielectric solution, was investigated. The rest-potential of the dental Ag-Pd-Cu-Au alloy was high in 1% NaCl and 1% C3H6O3 solutions and low in artificial and human salivas. The corrosion rate, which was measured by anodic polarization, was fastest in the 1% NaCl solution, followed by artificial saliva and 1% C3H6O3 solution. The rate was slowest in human saliva. An aged specimen and an as-casted specimen were quickly corroded. The AgCl was produced at the specimen surface in the 1% NaCl solution as well as the artificial and human salivas during the polarization measurement. Ninety percent of the ions released from the as-casted specimen immersed in the human saliva was Cu. The amount of ion release of Cu and Ag in the human saliva strongly depended on the heat treatment. The amount of Cu and Ag ions released in the human saliva decreased with an increase in immersion time. Fine, needle-like crystals of HAp covered the surface of the speciment immersed it the human salive and the calf serum.
