Preparation And Properties Of Carbon Series Filled Silicon Rubber Ablative And Adiabatic Composites

The internal design of thermal insulation blanket in the solid rocket motor is one of the key techniques to insure proper operation of the rocket engine.New application environments and requirements including lightweight,thermal insulation for a long time,high effectiveness thermal insulation,high reliability,etc,have been put forward to protective materials used and structure of thermal insulation blanket with the high energy propellant used widely and the advanced powder charging design and large charging casting process arise.Silicone rubber based ablation resistant and insulation materials have the characteristics of low density and thermal conductivity,excellent heat absorption ability,ablation resistance and thermal stability,etc.The materials can be applied to flight for a long time,ablation resistance for a long time,shearing of high flow,and good performance of thermal insulation.But silicone rubber based ablation resistant insulation materials have lower char yield,enduring poor erosion ability and the disadvantage of thermal protection in extremely high temperature.In addition,a large number of complex physical and chemical changes happen to the materials when are in the high-temperature environment.It is of important significance to develop and prepare new silicone rubber based ablation resistant insulation materials and forecast on ablative performance of materials.Firstly,basic formula(C-SR-BF)of carbon series filled silicone rubber ablation resistant and insulation composite materials(C-SR)were prepared using methyl vinyl silicone rubber(VMQ)and methyl phenyl vinyl silicone rubber(PVMQ)as matrix,white carbon black and carbon black as reinforced fillers.The effect of the content of fillers on properties of the material of C-SR-BF were studied.The results of experiment show that thermal stability of PVMQ is superior to that of VMQ;the reinforcing effect of silicone rubber is achieved by adding carbon black,but the specimen of filling carbon black has a substantial loss of mass.The C-SR-BF is formed by 50 VMQ,50 PVMQ and 30 white carbon black.Secondly,powders of carbon series filled silicone rubber ablation resistant and insulation composite materials(CP-SR)were prepared using nano-graphite and carbon black as fillers.The effect of the content of fillers on propertie of CP-SR were studied.The results of experiment show that the best tensile properties of specimen are achieved while filling 10 nano-graphite,the tensile strength and elongation at break of are 4.96 MPa and 1152% respectively;the ablation property of CP-SR is improved by adding nano-graphite,especially it can reduce linear ablation rate;the tensile strength and modulus of the specimen are both increased by adding nano-graphite and carbon black compound,when the composite ratio is 2/5,specimen can resist the washout of air flow of high-temperature and high-speed,the tensile strength and elongation at break of are 5.61 MPa and 2819.5% respectively.Finally,The effect of the content of fibers of carbon series including carbon nano tube(CNTs)and carbon fiber(Cf)on tensile property,ablative performance and thermal insulation property of the fibers of carbon series filled silicone rubber ablation resistant and insulation composite materials(CF-SR),and the effect of splicing carbon fiber cloth on the surface of CF-SR specimen on ablative and thermal insulation properties,were studied.The experimental results show that the property of materials is significantly improved by adding bits of CNTs,the tensile strengths of specimens are 4.86 MPa and 4.66 MPa while filling 0.5 and 10 CNTs;The average linear ablation rate is 0.1mm/s when the additive amount of CNTs is less than 3,this indicates CNTs has excellent ablative performance.The tensile strength of Cf-SR specimen is 4.3 MPa when 10 carbon fiber are filled;The quality ablation rate and linear ablation rate are 0.0091 g/s and 0.031 mm/s when 20 carbon fiber are filled,this indicates carbon fiber can improve ablative performance of materials dramatically.The tensile property,dynamic shock resistance and ablative performance and thermal insulation property of CF-SR specimen are all enhanced when composite one layer,two layers and three layers carbon fiber cloths on the surface of CF-SR specimen.