Developments of Multi-Functional Ceramics (MFC)

Abstract

MFC based on SrTiO3 or (Sr, Ca)TiO3 ceramics were developed as a noise and surge absorption element. They have both characteristics of varistor and capacitor. They showed the excellent electrical characteristics such as ε s.app; (6-40)×104, a; 10-20, the current surge absorption capabilities; 3000A/cm2 and so on. The semiconductive ceramic grains and the grain boundaries of a SrTiO3 ceramic with a BL structure were much effective on these electrical characteristics. So, these electrical characteristics were obtained by controlling the BL structure of (Sr, Ca)TiO3 base ceramics. The grain sizes of SrTiO3 ceramics were controlled between 10μm and 150 μm.In addition, The increase of the leakage currency through a MFC was unobserved after supplying several high surge impulses, while that of a ZnO ceramic varistor was much more in the same condition.When MFC was applied on a power transformer circurt and a fast rise-up impulse noise were supplied to the cercuit, it has been comfirmed that the induced noise level observed on a secondary transformer circuit can be depressed to lower level. In consequent, MFC is available to prevent electrical equipments from being damaged by a noise or a high surge energy.