Study And Preparation Of MgO Whiskers Based On The Use Of Magnesium Carbon Material

The reuse of used magnesia-carbon brick is mainly to study and utilize the aggregate with different particle size,but the use of the remaining fine powder is very little.The fine powder contains a large amount of magnesium and carbon resource,if we can make full use of the fine powder,it will save a lot of resources.Starting from the raw materials for preparing whiskers,the magnesium oxide whiskers were prepared by carbon thermal reduction.With the high purity magnesia and fine powder regenerated from magnesia carbon as the main raw materials.Magnesium oxide whiskers were prepared by carbon thermal reduction.As a kind of inorganic whisker with potential development,magnesium oxide whisker has the advantages of high mechanical strength,high melting point,high heat resistance,good insulation,great heat conductivity,which is suitable for reinforcing and toughening composite materials.Through thermodynamic analysis and calculation,the effects of molar ratio(C:Mg O),sample molding pressure,calcination temperature and admixture on whisker production were studied,and analyzed the growth mechanism of whisker.The morphology of the product was characterized by SEM,the phase composition of the whisker was determined by XRD,the components of the whisker were analyzed by EDS.The results indicate that:(1)Magnesium oxide whiskers made by high purity magnesia and flake graphite who have low yield,only up to 2.05 percent,and a short whisker length ranging from10 to 100 ?m.(2)Magnesium oxide whiskers were prepared from regenerated magnesium carbon brick powder,the calcination temperature should be controlled at about1550 ?,the molar ratio(C:Mg O)= 2,the molding pressure of the sample is 150 KN,and the magnesium oxide whisker yield is the highest,the weight loss percentage of the sample reached 28.12%.The columnar whiskers range in diameter from 5 to 40?m and in length from 100 to 800 ?m.The yield of whisker changed after adding admixture,the addition of boric acid is beneficial to whisker formation,the addition of Fe2O3 powder less than or equal to 1.5% is not conducive to the formation of whiskers,while the addition of 2% Fe2O3 powder is conducive to the production of whiskers,the addition of metallic aluminum powder is not good for whisker growth.(3)Through XRD diffraction analysis,the phase composition of the product iscalcite.SEM analysis results show that the microstructure of Mg O whiskers morphology showed a variety of shapes,most of which were irregular columnar growth,and some of which were flower-shaped or scaffolded.(4)Magnesium oxide whiskers prepared by carbon thermal reduction mainly grew by VS mechanism,and the growth of the whisker most changed to VLS mechanism after adding metal aluminum powder.