| 摘要 |
PURPOSE:To directly obtain a zirconia refractory from an inexpensive natural zirconia ore at a low cost by adding calcium hydroxide to monoclinic zirconia occurring in nature, calcining and stabilizing the resulting mixture, and then subjecting the above to compacting and sintering. CONSTITUTION:Calcium hydroxide is added to monoclinic zirconia occurring in nature, and the resulting mixture is compacted and sintered so as to be formed into the desired refractory. It is preferable to regulate the additive quantity of calcium hydroxide to 5-9wt.% expressed in terms of CaO, and further, it is also preferable to carry out calcination treatment at >=1200 deg.C for >=2hr. When the calcination temp. is 1100 deg.C, the progress of stabilization is not sufficient, and stabilization rapidly proceeds in the course from one to two hours after the calcination is initiated. The stabilization of monoclinic zirconia can be attained at low temp. by stabilizing it by means of calcium hydroxide, and further, by using the above monoclinic zirconia, the zirconia refractory having sufficient strength and reduced in coefficient of thermal expansion can be inexpensively mass-produced. |
