TiAlN Thin Films as High Temperature Strain Gauges

A custom built measurement setup is used for the evaluation of the gauge factor and the temperature coefficient of resistance (TCR) of TiAlN thin films up to 350 °C. The films are sputter-deposited on a sapphire beam from a TiAl target in a nitrogen atmosphere. The gauge factor at room temperature is about 2.5, decreasing only moderately at 350 °C. In this temperature range, the TCR is about -1.75·10-4 K-1 being significantly lower than that observed at platinum which is taken as reference. The excellent mechanical stability of TiAlN and the low temperature dependency of both the gauge factor and the electrical resistance make this material a promising candidate for a new generation of strain gauges which can be operated reliable even at temperatures above 350 °C.