| 摘要 |
PROBLEM TO BE SOLVED: To provide a porcelain insulator enhanced in dielectric breakdown strength or surge-wave strength without lowering mechanical strength, and provide a manufacturing method thereof. SOLUTION: This porcelain insulator is made up of a porcelain insulator body 1 and a coating layer 2 provided on the surfaces of the porcelain insulator body 1, mainly composed of a porcelanic raw material containing a high-permittivity material, having minute portions within so uniformized that the ratio of the maximum size thereof to the minimum size is 2 or less in the thickness direction of the coating layer, and having a relative permittivity of 4 or more. In the manufacturing method thereof, (1) a porcelain insulator body is prepared, (2) a porcelain raw material comprising SiO2 of 50 to 60 wt.%, Al2O3 of 20 to 30 wt.%, and the remainder, MgO, CaO, K2O, and Na2O, is prepared by pulverizing a raw material and mixing clay therein, a high-permittivity material having a relative permittivity of 10 or more is separately prepared, thereafter a coating material is prepared by adding the high-permittivity material of 3 to 10 pts.wt. to the prepared porcelanic raw material of 100 pts.wt. and blending them into slurry, (3) surfaces of the porcelain insulator body are coated with the coating material, and (4) the porcelain insulator body having the surfaces coated with the coating material is baked.
|
