Characteristics of the Torque Sensor Usins Plasma-Sprayed Ni Layer--Effect of the Heat Treatment of the Ni Layer

A magnetostrictive Ni layer, plasma-sprayed onto a shaft, was used in conjunction with a pair of magnetic heads to measure the torque exerted on the shaft. Whereas the as-sprayed film had a high coercivity, annealing for two hours at from 500 to 1000°C lowered the coercivity, and caused the film to become magnetically more homogeneous. An example of the detection of transient fluctuations in the applied torque is also presented.