[Corrosion behavior of palladium-based alloys]

The electrochemical corrosion behavior of 45 palladium-based alloys both in the original state as supplied by the manufacturer and after casting was tested by potentiodynamic polarisation under quasi-stationary conditions. Based on the results of these tests the palladium-based alloys studied were classified as three different types. Showing a flat curve without pronounced corrosion peaks, type 1 corresponded to a high gold alloy. Type 3, with several pronounced corrosion peaks, resembled the well-known silver-based alloys. Type 2 showed a marked peak thus ranging halfway between type 1 and type 3. Product-related fluctuations in peak height were more frequently found in type 2 and 3 than in type 1. Casting brought about greater changes in the corrosion behaviour as against the original untreated state in types 2 and 3 than in type 1. With few exceptions the alloy composition could be attributed to the individual types. Apart from most of the type 3 palladium-based alloys almost all alloys contained gallium which is not permissible in non-precious dental alloys.