摘要 |
PURPOSE:To obtain sintered black alumina having excellent electrical, mechanical and thermal properties by adding a specific amount of a black pigment containing Fe2O3 to Al2O3 as a major component. CONSTITUTION:85 to 98wt.% of alumina (for example, alpha-alumina of high purity and small particle sizes) is mixed with 2 to 15wt.% of the components selected from (a) Mn2O3 and Fe2O3, (b) Fe2O3 and CoO, (c) Cr2O3, Mn2O3, Fe2O3 and CoO (for example, (c), namely a combination of 4 components is preferred). The average particle size of these starting materials is preferably less than 10mum. When being mixed, a binder, a dispersant, a lubricant, a defoaming agent and the like can be added. They are mixed in a ball mill in the presence of a solvent such as water, then pressed into a desired shape. Sintering is effected at 1550 to 1650 deg.C in an oxidative atmosphere containing air or oxygen under 1 to 1.5 atmospheric pressure. The product is useful as a precise ceramic such as an electronic part, a semiconductor production part or a variety of measuring devices. |