Corrosion-fatigue of the bond between nickel-chrome casting alloys and porcelain

This study was designed to determine if corrosion-fatigue might play a part in early failure of the porcelain-fused-to-metal bonds with Ni-Cr alloys. A qualitative test was used that compared the bond strengths of a control group with those of samples subjected to corrosion-fatigue. One Au-Pd alloy was used for comparison with the Ni-Cr alloys. The bond strengths were determined with a shear-push through test in an M.T.S. hydraulic testing machine. Two additional groups of samples were tested with corrosion only and fatigue only. All samples except those used for controls were placed in an oral environment chamber that had an aerated artificial saliva circulating through it maintained at 37 ° C. (Samples subjected to fatigue only used unaerated distilled water.) Corrosion was accelerated by enforcing a potential of approximately 500 mV on the test samples. The samples subjected to fatigue were stressed with a haversine waveform with a force between 5 and 45 pounds at a rate of 200 Hz for 10⁶ cycles.