Investigate On Property Of Low Carbon MgO-CaO-C Brick

With the increasing demand of clean steel and low carbon steel，and Environmentalprotection energy saving society is advocated.Therefore, the application of low carbonMgO-CaO-C refractories becomes an inevitable trend. In order to improve the performance ofmagnesium calcium carbon materials,dispersible uniformity and antioxygenc property ofcarbon is crucial.Moreover,hydration of CaO in MgO-CaO-C materials is unavoidable.Therefore,This work mainly includs three aspects, the choice of carbon sources, the relationship betweenthe resin pyrolysis and CaO hydration as well as the choice of antioxidants. The results abtainedare as follows.The specimens of low carbon MgO-CaO-C refractories with different kinds of carbon wereprepared. And bulk density, apparent porosity, room temperature compressive strength andthermal conductivity of the specimens were examined. The result proves that flake graphite assole carbon can be well dispersed in matrix of MgO-CaO-C refractories.A continuous uniformcarbon structure forms after carbonization, which makes the refractories show excellentperformances. However, flake graphite and superfine flake graphite as combined carbon sourcecan fill the pores of MgO-CaO-C refractories, which makes the materials formed networkmicrostructure in the matrix after carbonization.The materals have good performces while thebulk density, apparent porosity, room temperature compressive strength are decline with flakegraphite content increases.In order to investigate the relationship between the resin pyrolysis and CaO hydration in theheating process, MgO-CaO-C sample are prepared for TG-DSC analysis, and heated at390℃to550℃for XRD analysis. The result proves that CaO of MgO-CaO-C materials is hydratecaused by H2O which from the air and resin pyrolysis content. The hydration of CaO in thematerials can be restained through elevated heat treatment temperature and addition ofMgO-CaO powder.The appropriate heat treatment temperature is500℃, and the suitableaddition amount of magnesium calcium powder,which mixed with resin in advance,is4%.In order to improve the oxidation resistance of MgO-CaO-C refractories,SiC and B₄C uesdas antioxidant were added. The addition of SiC effectively improves the anti-oxidationperformance of the specinmens.The reaction of SiC and O₂after1200℃reduces the oxygenpartial pressure in the sample,and the formation of M2S block the pores to prevent the oxidationof carbon. The introduction of B₄C can also improve the anti-oxidation performance of thespecimens,and B₄C react with O₂after700℃,B2O3forming a liquid membrane in the surface ofsample to prevent the oxidation of carbon.The best way is SiC conbined with B₄C addition intothe specimens.Which made better anti-oxidation performance,and the suitable addition content is3%SiC and1%B₄C respectively.