Preparation Of Sucrose/Epoxy Carbon Foam And Simulation Study On Its Thermal Conductivity

Due to the diversity of carbon sources and preparation processes,carbon foam materials exhibit many excellent physical properties,such as light weight,good thermal stability,and low thermal conductivity,and have good application prospects in the aerospace field.For the preparation of carbon foam,the choice of carbon source is crucial.In the current experimental research,most of the carbon sources for the preparation of carbon foam are non-renewable resources such as asphalt,coal,resin,etc.,and the intermediate products in the preparation process have serious environmental pollution.At the same time,the prepared carbon foam materials have poor stability and raw materials.And the preparation process cost is high and the production cycle is long.In response to this research situation,based on the research of green low-cost sucrose-based carbon foam,this paper proposes to use sucrose as the carbon source,epoxy diluent as the gel carbon fixation system,and plant protein as the foaming agent.The foaming method produces a carbon foam with uniform pores.The effect of process parameters on its microscopic morphology,physical properties and mechanical properties is studied,and the relationship between parameters,structure and properties is explored.Since the thermal conductivity of the carbon foam meets a certain rule with the structure,in order to grasp the structure-thermal conductivity relationship,a three-dimensional model is established to conduct a finite element analysis of the thermal conductivity of the carbon foam,and the simulation results are compared with the test results to verify the feasibility of predicting the thermal conductivity of carbon foam by calculation.Sucrose/epoxy carbon foam materials with large and uniform surface structure were prepared through experiments,and the effects of component content(sucrose and blowing agent)on its structure and properties were studied.The results show that with the increase of sucrose content,the viscosity of the solution gradually increases and tends to saturate,the dimensional stability of the carbon foam increases,and the linear shrinkage rate gradually decreases;however,if the content of the blowing agent in the solution system is too low,the porosity of the material will result Lower,too highblowing agent content will reduce the mechanical properties of carbon foam.When the sucrose content is 40 wt.% and the blowing agent content is 3wt.%,the system has the best foaming effect,the carbon foam has the most stable and uniform size and performance,the average pore size is controlled at 258.3um,and the density is as low as0.13g/cm3,porosity is as high as 92.26%,compressive strength is 2.35 MPa,thermal conductivity is as low as 0.12W/(m·K).A three-dimensional stochastic model of carbon foam is established by means of random order addition.By controlling the porosity of carbon foam in the range of 50%to 90% and the average pore size in the range of 100 um to 400 um,the pore structure and thermal conductivity of the carbon foam are explored.relationship.The calculation results show that when the average pore size of the material is fixed,as the porosity increases,the thermal conductivity of the carbon foam shows a non-linear downward trend,from 2.23W/(m·K)to 0.15W/(m·K).When the porosity is constant,as the average pore size increases,the thermal conductivity of carbon foam increases first and then decreases.The function of thermal conductivity varying with porosity is used to establish a fitting equation,which is substituted into the actual carbon foam parameters.The obtained thermal conductivity prediction results are basically consistent with the experimental results,and almost consistent with the results of various empirical formulas.It shows that the finite element analysis of the material established by the stochastic three-dimensional model can predict the thermal conductivity of the carbon foam material by simulation under certain conditions.