Study On The Preparation Of High Density And High Strength Carbon/Graphite Materials By Mesocarbon Microbeads(MCMB)

High density and high intensity isotropic carbon/graphite material with excellent properties and high added value,it should be widely used in different fields,such as electrode,high heat exchanger,rocket larynx lining material and so on.Mesocarbon Microbead(MCMB)have good self-sintering properties,molding by cold isostatic pressing.After heat treatment,it can be sintered into high density and high strength carbon/graphite materials without binder.In this paper,the preparation of carbon/graphite materials with self sintering properties of MCMB as raw materials,the preparation of carbon/graphite materials without binder,and the addition of mesophase pitch and oxidized mesophase pitch to prepare carbon/graphite materials.The binderless carbon materials were prepared with 23?m MCMB as raw materials.The effects of temperature on the microstructure,thermal weight loss,line shrinkage,volume shrinkage,density,strength and resistivity,and the isotropy of carbon materials were discussed during the process of heat treatment.The thermal weight loss of samples mainly occurred at 250? to 900?.The material greater shrinkage occurred at 500? to 1100 ?.When the heat temperature was 1300?,the thermal weightlessness rate was 9.72%.the line shrinkage and volume shrinkage of material were 12.26%and 32.46%respectively The bulk density is 1.75g/cm3.The flexural strength and compressive strength were 83.5MPa,333MPa respectively,the isotropy was 1.04.The effects of 23?m MCMBs as raw material,adding different proportions of 1 ?m MCMBs and 5?m MCMBs crushing powder to the structure and properties of binderless carbon material.The results show that adding a certain proportion of 1 ?mMCMBs and 5?mMCMBs can increase the density of the raw and carbon materials,but the flexural strength didn't increased,and the carbon materials of adding 50wt%11?m MCMBs and adding 10wt%5 MCMBs were high density and flexural strength in the addition of different particle size powders.They were 1.86 g/cm3,1.83 g/cm3,82.6MPa and 36.6MPa respectively.The effects of different molding processes on the structure and properties of binderless carbon material was discussed.The proper increase of molding pressure and holding time can increase the properties of carbon materials.The molding pressure increases from 150MPa to 200MPa,the carbon material density increases to 1.85 g/cm3,and the flexural strength increases from 83.5MPa to 88.3MPa.The strength of carbon material prepared by holding 9min is increased by 5%compared with that of 3min;the flexural strength of carbon material prepared by 9min under 200MPa molding pressure increased by 11%compared with that of carbon material prepared under 150MPa molding pressure under pressure of 3min.The binder carbon material was prepared by adding mesophase pitch and mesophase pitch oxidation powder with 23?m MCMBs as raw material.The results showed that with the increase in the ratio of mesophase pitch,the density decreased from 1.85 g/cm3 to 1.79 g/cm3,and the flexural strength of adding 3%mesophase bitumen was the highest:85.4MPa.In order to reduce the larger pores produced in the process of heat treatment,the pores of the carbon materials prepared by the oxidation of mesophase pitch were obviously reduced,and the density and flexural strength were improved.The carbon materials with the best performace prepared by adding 3%mesophase pitch oxidation powder in 23?m MCMBs,the density and the flexural strength is 1.86 g/cm,94.6MPa respectively.Carbon materials with different preparation conditions and better properties were selected to graphitized at 3000?.The main 5 kinds are following:3 different 3 binderless carbon materials(150MPa molding,3min holding time and 200MPa molding,9min holding time,23?m MCMBs adding 50wt%?m MCMBs),2 kinds of carbon material of 23?m MCMBs adding binder(adding 3%mesophase pitch,adding 3%mesophase pitch oxidation powder).The graphitization degree of the 5 materials was concentrated between 72.6%-78.8%,and the highest graphitization degree of binderless graphite material prepared by 150MPa molding and 3min holding time was 78.8%.The density and flexural strength of adding 3%mesophase pitch oxidation powder graphite material were the highest,1.92g/cm3 and 59.0MPa respectively,and the strength of the graphite material was 33.2%higher than that of 150MPa molding and 3min holding time.