Research On High-temperature Adhesion Process And Mechanism Of Carbon Materials

In recent years,carbon materials represented by graphite and C/C composite hasbeen widely used in areas such as aerospace,chemical engineering, metallurgy andnuclear power because of its characteristics of low density, high thermal conductivity,high thermal shock and high mechanical properties at high temperature.Since adhesionmethod owns characteristics of low price and simple operation and has good bondingeffect to carbon materials,it has important application values to realize the adhesivejoints remaining valid connection after subjected to high temperature.This paper adoptsB,B2O3and B4C as main inorganic filler on modification for organic silicone resin toobtain high-temperature adhesive,bonds graphite and C/C composite with theadhesive,and deals with the joints with high temperature heat treatment.The influence ofheat treatment process parameters on joint microstructure and mechanical properties wasmainly studied. The evolution of joint microstructure and interface bonding mechanismwas analyzed deeply.B,B2O3and B4C powers was adopted as main inorganic filler to modify organicsilicone resin,bonded graphite with the resin,the graphite adhesive joints was dealt withhigh temperature heat treatment, the formula of filler was optimized.The influence ofdifferent heat treatment process parameters on joint interface microstructure andmechanical properties was studied. After high temperature heat treatment,adhesive layerformed honeycomb structure composed of carbon,B2O3,SiC and SiO2composite.Acarbon/glass/ceramic composite combination layer containing higher proportion of Sielement appeared on the interface.The effect is better when the B2O3and B4C filler wasused,the graphite joint with B4C modified silicone resin gained5.5MPa shear strength atroom temperature after800℃,30min heat treatment.B2O3powers was adopted as inorganic filler to modify organic siliconeresin,bonded C/C composite with the resin,the C/C composite adhesive joints was dealtwith high temperature heat treatment, the formula of filler was optimized.The influenceof different heat treatment process parameters on joint interface microstructureandmechanical properties was studied. After high-temperature heat treatment,adhesivelayer formed honeycomb structure composed of carbon,B2O3,SiO2,SiC and SiO2composite,The interface consisted of a carbon/glass/ceramic composite combinationlayer containing B2O3,SiC,residual carbon and borosilicate glass.The joint gained6MPashear strength at room temperature after700℃heat treatment. The adhesive joint evolution process was investigated,the results showed that thehigh-tempreture adhesive joint forming process included three stages:the organic siliconresin crosslinked and solidified under100℃，decomposed during400℃-550℃,the fillerreacted with thermal decomposition product above600℃and formed high-tempreturejoints.The interface bonding force between adhesive layer and carbon material matrix inroom temperature mainly consisted of the mechanical bonding force of resin “nailpiercing” on the matrix surface,absorption and covalentbonds produced by “bypass”effect of coupling agent.The interface bonding force after high-tempreture heattreatment consisted of the mechanical bonding force of glass phase “nail piercing” onthe matrix surface and chemical bonding force.The chemical bonding force consisted ofthree parts:the B－C,Si－C covalentbonds between B2O3,borosilicate glass and carbonatoms layer ofmatrix surface,the (111)SiC//(0001)graphiteclose stacking because of thecovalentbonds produced by Si－C covalentbonds of SiC ceramic phase from adhesivelayer and C－C covalentbonds of graphite.