| 摘要 |
PROBLEM TO BE SOLVED: To provide a zirconia-alumina composite sintered body excellent in water heat degradation resistance in addition to strength.SOLUTION: A zirconia-alumina composite sintered body consisting of 50 to 95 wt.% of zirconia containing yttria of 2 to 4 mol% and 5 to 50 wt.% of alumina, and having a relative density of 98% or more, an average particle diameter of zirconia crystal particles and alumina crystal particles of 0.4 μm or less, a tetragonal percentage of a zirconia crystal phase of 85 wt.% or more and the number of coarse alumina polycrystal particles consisting of 20 or more alumina crystal particles is one or less in a field of 240 μm×180 μm in an electron field emission scanning type electron microscope is used. The composite sintered body is obtained by adding an aluminum compound of 0.05 to 1 wt.% in terms of oxide to a calcined powder obtained by adding a yttrium compound of 2 to 4 mol% in terms of oxide to a hydrated zirconia sol which is obtained by hydrolysis of a zirconium salt solution and has the reaction rate of 98% or more, drying and calcinating in a range of 900 to 1100°C, pulverizing them till a BET specific area of 9 to 20 m/g and an average particle diameter of 0.5 μm or less, then mixing and pulverizing alumina powder whose BET specific area is 10 to 20 m/g and average particle is 0.5 μm or less so that alumina concentration is 5 to 50 wt.% to obtain a mixture powder, and molding the mixture powder and sintering at 1200 to 1400°C. |
