Researches on Substrates of High Temperature Eddy Current Sensor

In this paper, substrates of eddy current sensor were composed by silver films and glass ceramic disks, all of these can resist high temperature . The thin silver films were deposited by radio frequency magnetron sputtering on machinable glass ceramic at room temperature. Variations of sputtering power, bios voltage and power density were carried out for each deposition, then parts of as-deposited samples were subjected to annealing at 600 ? within a vacuum chamber. Structural properties were studied by X-ray diffraction (XRD) and scanning electron microscope (SEM). It was shown that structural properties had a strong dependency on sputtering power and annealing temperature. Electrical contact resistance measured by a four point probe instrument was directly affected by the thickness of films. It was also found that the film conductivity, especially in thinner films, was improved by the increasing grain size. Further more, the film adhesion was observed by scratch tests experiment. Finally, the subsequent processes of high temperature eddy current sensor were introduced.