The sheet resistivity of tin dioxide films deposited by electron-beam evaporation has been studied during annealing, both as a function of time and temperature. The annealing behaviour of SnO₂ films under the above two different conditions is consistent. A qualitative interpretation has been given for the decrease and the minimum observed in the resistivity. The increase in resistivity has been confirmed by scanning-electron micrographs. The films were also characterized by x-ray diffractometry.

This paper presents the cumulative damage in glass fibre reinforced plastic composite during loading and unloading at regular intervals using the continuous monitoring of ultrasonic test instrument. The result shows that the ultrasonic attenuation increases with an increase in the tensile load, which provides the change in internal damage of composites.

An ultrasonic technique has been used to evaluate the degradated fatigue life of glass fibre/zirconia hybrid composites in different concentrations of sodium chloride and sulphuric acid. Results indicate that reduction in fatigue life of hybrid composites increases with increase in ultrasonic attenuation. Ultrasonic attenuation can be used to predict the fatigue life of hybrid composites before and after service.