Preparation Of Modified Sintered Magnesia University Of Science And Technology Liaoning

Magnesite is the main basic material for the production of basic refractories.It is high in melting point,and it has the strong resistance to alkaline slag erosion.So,Magnesite is used in refractory of converter,electric furnace,ladle and industrial furnace for outside refining and non-ferrous smelting.Magnesia is made of periclase phase,crystal phase and Intercrystalline silicate phase.The dilatation coefficient of periclase is high,this leads to poor thermal shock stability of magnesium refractories.The melting point of intercrystalline silicate,it is the main channel for slag intrusion in the process of application.These characteristics limit the use of the sand of magnesia.Magnesite which was from yingkou dashi bridge areas in Liaoning is used as raw material.The lightly burned magnesia powder was prepared by The two-step calcining method in this reasech.The relationship between calcining temperature and the particle size of magnesite on the activity and microstructure of lightly burnt magnesia was investigated.The following conclusions are obtained through experiments and analysis:1.In the range of experimental temperature,the activity of lightly burned magnesia first increased and then decreased with the increase of calcining temperature.At the same calcining temperature,the activity of magnesite increases with the decrease of grain size.And calcined at 700℃temperatures had highest activity of light burned magnesia,1000℃temperature calcining the light burning magnesium oxide activity in the form of a minimum.2.Temperature rise and magnesite decomposition trend accelerated,at 700℃has been decomposed completely;At the same temperature,when the particle size is smaller and smaller,the crystal development of magnesia calcite is more complete,the crystal growth trend of magnesia calcite is obvious,the sintering effect between magnesia calcite and magnesia calcite is obvious,the sintering shrinkage rate is higher,the sintering trend is more obvious3.The atmosphere didn`t affect the product of the sample,but the high-activity light burned magnesium powder was more conducive to the crystallization of the burned product,so that the grain development was better.4.When the amount of aluminum powder is 10%and 15%,the non-oxide appears in the sample.The non-oxides are mainly distributed on the surface of pores and granules,and the microstructure is flaky and fibrous.The samples fired under nitrogen atmosphere contain a large amount of non-oxide,which are mainly MgAlON,AlON,AlN and Sialon phases.The non-oxide content of the samples burned under the atmosphere of carbon implantation was low,mainly composed of MgAlON,AlON and AlN phases.5.When metal silicon powder was added,no sintered magnesia with non-oxide binding was generated,and the main crystal phases were MgO and 2MgO·SiO₂.