| 摘要 |
PURPOSE:To make uniform the property of porcelain by baking piezo-electric porcelain elements by adding Al2O3 setters having the porosity of 20-35% and the purity of 98% or more between the elements in baking the elements by stacking wherein cracks and the scattering of PbO are prevented. CONSTITUTION:Piezo-electric porcelain elements 3 are formed by adding a suitable binder to ceramic powder and dry molding is applied to the available powder body. Bed powder 2 for reaction proof is spread in a vessel 1 for calcination and the elements 3 are stacked on the powder 2 by inserting each Al2O3 setter 4 having the porosity of 20-35% and the purity of 98% or more between the elements 3 for calcination. The variations of electrical and porcelain characteristics by the scattering of PbO at the upper and lower-stage elements 3 are prevented as high-purity Al2O3 setters 4 with good thermal conductivity lie between the stacked elements 3. The variations will increase if the porosity of the setters 4 exceeds 35%. The elements at the middle stage will show poor calcination at the porosity of 20% or less. |
