| 摘要 |
PURPOSE:To obtain this porcelain composition which is large in dielectric constant and low in the voltage of a varistor and large in alpha(voltage - current nonlinear exponent) and resistant amount to surge by adding the roasted material of the mixture of SrTiO3 and SiO2 to the mixture of the specified Sr- Ca-TiO3 component, Nb2O5 and Al2O3, etc. CONSTITUTION:The porcelain composition is obtained by adding 0.001-10.000 pts.wt. additive which is obtained by firing the mixture consisting of 60.000-32.500mol% SrTiO3 and 40.000-67.5mol% SiO2 at >=1200 deg.C to 100 pts.wt. main component contg. 90.000-99.998mol% formula I (0.002<=x<=0.300, 0.950<=a<1.000), 0.001-5.000mol% one or more kinds selected from among the group of formula II and 0.001-5.000mol% one or more kinds selected from among the group of formula III. Since the composition is large in the diameter of a particle, voltage of a varistor is low and both dielectric constant epsilon and alpha(voltage - current nonlinear exponent) are large and dispersion of the diameter of the particle is small. Therefore surge current is allowed to uniformly flow to an element and resistant amount to surge is made large because grain boundary is effectively made to high resistance by Ca. |
