| 摘要 |
PURPOSE:To raise the Curie point without adding any additive and prevent crack initiation by impressing a specific electric field to a molding until the temp. of the hot molding after the firing process attains its Curie point. CONSTITUTION:In the molding process, a molding is yielded form a mixture powder of PbO and TiO2. In the firing process, this molding is heated to undergo firing, and when it is finished and the temp. of molding is going to decrease, an electric field of 1-10kV/mm is impressed to the molding at least until the Curie point is attained. Therefore, re-orientation of grains takes place in the molding at a temp over the Curie point. The orientation direction of grains at this time of re-orientation does not change substantially even after the molding is cooled to below the Curie point, and because the orientation direction is retained and stress generation is prevented, this molding consisting of Pb titanate is free form crack initiation. Thereby crack initiation is prevented without including any additives, and the Curie point can be heightened. |
