Study On The Formation Mechanism Of Mg Al On In Magnesium Materials By Different Aluminum Source

Magnesian materials have characterisitics of high firing temperature and poor thermal shock resistance,Therefore,it is especially important to improve the thermal shock resistance of magnesian materials.Previous study showed non-oxide could generate in carbon-containing refractories by adding metal aluminum.Non-oxide Mg Al ON have excellent properties,which is a kind of new high temperature material and Mg Al ON can formed by Mg O solid solution to Al ON.Mg Al ON has good slag resistance,no pollution to molten steel and excellent high temperature properties.So it improve high temperature mechanical properties and thermal shock resistance of magnesia refractory by forming a fiber structure in the refractory.In magnesian material Mg Al ON is formed by in-situ reaction through introduced aluminized raw.Therefore,it is necessary to study the formation mechanism of the Mg Al ON in magnesian refractories using different aluminum source.It is expected to provide theoretical basis for the preparation of metal composite magnesian material.The main research contents of this paper is effect of heat treatment temperature and adding amount and addition way of aluminum source to formation mechanism of the Mg Al ON in reducing atmosphere of buried carbon and nitrogen atmosphere.The aluminum source include metal aluminum powder,magnesia-alumina spinel powder,?-alumina powder,metallic titanium powder.The mineral composition microstructure and micro area composition of samples were analyzedsysed by XRD,SEM and EDS.It was concluded that aluminum melted to form holes in the sample of added aluminum,The fibers and plates Mg Al ON phase could be formed therein.The formation of Mg Al ON is controlled by liquid-gas reaction.The nitrogen partial pressure and temperature affect the amount and structure of Mg Al ON.When the amount of nitrogen is insufficient,or the temperature and the content of alumina are low,Mg Al ON rapidly grows along the specific crystal plane and forms fiber whiskers.When the temperature and the amount of nitrogen increase,all crystal planes of Mg Al ON can rapidly grow to form sheet space structure.the optimal temperature is1400 ? for Mg Al ON formation in reducing atmosphere of buried carbon.The addition methods of aluminum source form strong to weak is: only adding metal aluminu>joint adding metal aluminu and magnesia-alumina spinel>joint adding metal aluminu and ?-alumina,the best addition amount of metal aluminu alone is 40%.the lowest heat treatment temperature for Mg Al ON formation in nitrogen atmosphere is1400 ?,Mg Al ON is fiber structure.At 1500 ? Mg Al ON structure is fiber and e sheet space structure,The addition methods of aluminum source form strong to weakis: joint adding metal aluminu and magnesia-alumina spinel>joint adding metal aluminu and ?-alumina>only adding metal aluminu>joint adding metal aluminu and metallic titanium,the best addition amount of metal aluminu and magnesia-alumina spinel are 26% and 40%.