oa Palladium-Chromium Strain Gauges

In order to meet urgent needs in aerospace research, an electrical resistance strain gauge of palladium-13 weight per cent chromium alloy is being developed both in fine wire and thin film forms at the NASA Lewis Research Center. The wire strain gauge has platinum wire wound around the gauge grid to serve as the temperature compensator, and is coated with a special alumina-based overcoat. This gauge has a sufficiently small apparent strain, with good reproducibility between thermal cycles to 800°C. The apparent strain of the gauge can therefore be corrected within a reasonable error up to this temperature. The thin film gauge, which provides a means for non-intrusive strain measurements, demonstrates the possibility of extending the use of this palladium alloy to approximately 1000°C.