| 摘要 |
PURPOSE:To provide fine and homogeneous crystal grains and contrive both improvement in cutting properties and reduction in frictional coefficient, by adding MgO and Al2O3 to a CaBiO-TiO2 based dielectric porcelain material containing ZnO added thereto to provide a specific composition. CONSTITUTION:A dielectric porcelain material obtained by adding 0.5-7.0 pts.wt. ZnO, 0.5-5 pts.wt. MgO an/or 0.5-15 pts.wt. Al2O3 to 100 pts.wt. basic composition expressed by the formula (x is 40<=x<=85 by composition mol% and y is 0.005<=y<=0.6 by composition molar ratio) and calcining the resultant mixture. In this case, fine and uniform crystal grains are contrived by the adding the MgO. If the amount of the added MgO is 40.5 pt.wt., such effects are insufficient. If the amount exceeds 5 pts.wt., pores are conversely increased to deteriorate processability. If the Al2O3 is added, protruding parts are formed on the surface of the dielectric porcelain material to provide point contact, resulting in reduction in friction. Accordingly, the amount of the added Al2O3 is preferably >=0.5 pt.wt. If the amount is too large, the material is excessively hardened to deteriorate workability. As a result, the amount is preferably <=15 pts.wt. for practical use. |
