Study On Fabrication Of γ-AlON Translucent Ceramic Powder And Its Densification

Aluminium oxynitride(γ-AlON)with spinel-structure is a stable solid state ceramics in the Al₂O₃-AlN system.γ-AlON has become a new and potential material, because of its good optical,mechanical and physical chemical properties.In this paper the results of the investigation of the thermodynamic properties ofγ-AlON is presented.Fine and homogeneous transparentγ-AlON ceramic powders with different mole ratio of Al₂O₃ and AlN were synthesized by a new rapid synthesis processing,which is easy to be crashed.The relationships between properties of synthesized powder and synthesis process parameters were studied.The optimal synthesis parameter is 1700℃for 10min with 100℃/min in N₂ atmosphere (0.5bar).We studied the relationship ofγ-AlON between nitrogen content and its lattice parameter.Kinetic Analysis for formation ofγ-AlON solid- solution has been done and activation energy Q for solid solution formation by a rapid synthesis processing were calculated as 221.94 KJ/mol.Carbothermal nitridation synthesis ofγ-AlON powders has been performed by this rapid synthesis method.We gained the mixture of AlN and Al₂O₃.Then we synthesized theγ-AlON with the mixture powder which has removed carbon.From the results,we think that it will be a potential method.The effect of sintering temperature and soaking time by the pressureless sintering of the synthesizedγ-AlON powder was researched.We can know that sintering temperature is 1950℃and soaking time is more than 10h.The prepared transparentγ-AlON ceramics has good optical and mechanical properties at 1950℃for 10h. Microstructure observation displayed the samples had high densifiction and uniform structure and secondary grain boundary phases were not observed.