| 摘要 |
<p>PURPOSE:To obtain the title bracket excellent in both of strength and beauty, having the good slidability with a metal and sufficiently obtaining correction effect, by forming said bracket from light pervious zirconia ceramics containing Y2O3 and TiO2. CONSTITUTION:A starting raw material is desirably composed of a high purity tine powder. For example, hydrated titanium obtained by the hydrolysis of titanium alkoxide is added to a ZrO2-Y2O3 powder having a particle size of 0.3mum or less and the resulting composition is mixed, dried, baked and ground to obtain a pref. fine powder. The baking of a powder molding is pref. performed at 1300 deg.C or more within an oxygen atmosphere and the baking temp. is pref. set to 1600-1800 deg.C in order to achieve the sufficient growth of a particle. The baked body is treated in a hot isotactic press apparatus in order to obtain high light perviousness. The light transmissivity of the light pervious zirconia sintered body is not dependent on a particle size too much and is 54-67% in the case of a particle size of 20mum and 59-68% in the case of 200mum. Contrarily, the strength of said sintered body is dependent on the particle size.</p> |
