Consolidation of Aluminium Oxynitride Powders Using Hydrolysis of Aluminium Nitride

One of the materials with high potential for application as a refractory material is aluminum oxynitride with spinel-type structure, γ-alon. Alon materials, single-phase or composites, are characterized by good mechanical properties, high thermal shock resistance and a high corrosion and erosion resistance. Another advantage is possibility of usage of SHS method for producing of relatively good sinterable powders of γ-alon, however, are characterized by poor compressibility. This paper describes a method of compaction of SHS-derived γ-alon powder using the hydrolysis reaction of aluminum nitride, which is one of the products of SHS synthesis. The green bodies made from the powder with addition of 10 mas.% of water after two weeks of storage reach a strength level up to 30 MPa and an open porosity of less than 30%. Pressureless sintering of the such compacts allows to achieve 95% of theoretical density at 1700°C in less than one minute.