Preparation And Performances Of ZrO₂-AlN-Al Multiphase Material

Zirconia（ZrO₂） has high thermal expansion and bad thermal shock resistance. Aluminum nitride（AlN） has high heat conductivity and low heat expansion. According to modified principle of multiphase ceramic material, aluminum is introduced to zirconia and sintered under the nitrogen. The new material with characters of stand fire and low heat expansion and high thermal shock resistance will be gained.ZrO₂ and AlN and Al were used as raw materials; ZrO₂-AlN-Al multiphase materials were prepared by the two-step sintering （prenitriding under 1000℃×6h,then nitriding sintering under 1600℃×4h） and the direct recombination （nitriding under 1600℃×4h）. Performances of multiphase materials were researched on sintering and micro-structure; phase composition and thermal expansion and oxidation resistance and thermal shock resistance.The results show that: with the molding pressure increasing, apparent porosity of sample is reduced gradually, and sample’s density increases. When the molding pressure is 54MPa, the bending strength of sample is 43.19MPa. Proper grain composition of ZrO₂ and Al is 11μm and 29μm; sample’s density is high, meanwhile the oxidation resistance and thermal shock resistance of sample are excellent; the cumulative weight gain of sample after being oxided is less than 8 mg. With the intake of Al increasing, sample’s density and bending strength are reduced, but the thermal shock resistance improves. When the intake of Al is 10%, the bending strength conservation rate of sample after once and three times and five times thermal shock is 34.5%; 10.57%; 9.1%. Respectively two-step sintering method is better than direct recombination method to prepare ZrO₂-AlN-Al multiphase materials with excellent sintering properties, oxidation resistance and thermal shock resistance.