Anodic polarization behavior and microstructure of a gallium-based alloy

• Published in: Dental materials 1993-07, Vol.9 (4), p.234-241
• Main Authors: Oshida, Y., Moore, B.K.
• Format: Article
• Language: English
• Subjects: Corrosion; Dental Alloys - chemistry; Dental Amalgam - chemistry; Dentistry; Electrogalvanism, Intraoral; Electron Probe Microanalysis; Gallium - chemistry; Mercury - chemistry; Microscopy, Electron, Scanning; Silver - chemistry
• ISSN: 0109-5641; 1879-0097
• DOI: 10.1016/0109-5641(93)90067-Z

A gallium-based alloy (GA) that was developed as a substitute for dental amalgam was investigated for anodic polarization behavior in deoxygenated Ringers solution, 37°C. The related microstructures were examined and microanalyses were conducted. Four polarization tests were conducted by scanning from −300mV to +1,000 mV (vs. SCE) at 2 mV/s. Polarization of the first sample (GA-1) was stopped after the first anodic dissolution peak (−100 mV, 1.5–2.0×10 −3 A/cm 2). The fourth sample (GA-4) was interrupted at the secondary peak (+1000 mV, 0.3 A/cm 2). It was found that (1) the early stage of the first peak is related to selective dissolution of divalent tin ions, followed by a dissolution of Ga. Transmission electron diffraction (TED) identified the brown corrosion product as Ga 2O 3; (2) the GA-4 sample was covered with the white corrosion product of mainly Sn +4, identified as SnO 2. In addition, the current density of the GA sample when coupled with a high-copper dental amalgam was 0.03 A/cm 2 (with +1,000 mV) at the second peak which was about a ten times lower value than for the uncoupled sample; (3) the uncoupled gallium alloy and gallium alloy coupled with a high-copper dental amalgam showed 10 3 − 10 4 times higher anodic current density than that of an uncoupled high-copper dental amalgam, suggesting that the gallium alloy is more corrosion prone.