| At first, it introduces the research current status inside and outside of aluminum oxynitride spinel (A1ON), MgAlON and their composites, considering the abundant bauxite resource advantage in our country, beginning the pilot study on the fabrication, properties and microstrucrure of AOs-bauxite-based MgAlON composite.Effects of some technological parameters on the sintering properties, high temperature and microstrucrure of A -MgAlON composite fabricated by adding the presynthesized bauxite-based MgAlON or alumithermal nitridation reaction sintering have been systemically studied, and the better technological parameters are: using electrically fused alumina as aggregate, alumina and 10-20% bauxite-based MgAlON powder as well as 1.5%Y2O3 as matrix, the pressed samples sintered at 1500癈 X 6h(at 1200癈 holding 2h) have better sintering properties, high temperature properties and the greatly increased strength after three times wind cooling of thermal shock resistant test.By alumithermal nitridation reaction, using bauxite or alumina, Al and MgO powder as raw materials of the matrix, bauxite-based or alumina-based reaction sintering AliOs-MgAlON composite have been fabricated, and the sintering properties of the latter are better than the former. The properties of the composite fabricated by reaction sintering can achieve that of composite fabricated by adding presynthesized MgAlON.The MOR-T curves of bauxite-based and alumina-based composite belong to I kind curve of refractory, and the strengths at high temperarure are higher than the one at room temperature; The temperatures for the highest strength of the bauxite-based and alumina-based Al2O3-MgAlON composite areOxidation resistance property of AL2O3-bauxite-based MgAlON composite isbetter than that of bauxite-based MgAlON; Oxidation resistance property of alumina-based MgAlON composite is better than that of auxite-based MgAlON fabricated by the same technological; For the two composites, a dense protection layer can be formed during oxidizing, which will be advantageous to the property of oxidation resistance.Hydratability resistance ofbauxite-based MgAlON composite is much better than that of A1N material; For bauxite-based MgAlON composite fabricated by adding the presynthesized bauxite-based MgAlON or alumithermal nitridation reaction sintering, hydratability resistance of the block is better than that of the powder; Hydratability resistance of the specimen fabricated by reaction sintering is better than that of the specimen fabricated by adding the presynthesized bauxite-based MgAlON.Sum up the properties, bauxite-based MgAlON composite, especially the one fabricated by reaction sintering has fine properties, which are close to that of Aalumina-based MgAlON composite, the advantages of low cost and simple technological at the same time. In some condition, it is hoped to be used instead of A^Os ?alumina-based MgAlON composite, and has the good exploiture and application foreground. |
