Thermal Protection Performance of Carbon Aerogels Filled with Magnesium Chloride Hexahydrate as a Phase Change Material

Carbon aerogels are comprised of a class of low density open-cell foams with large void space، nanometer pore size and composed of sparsely semi-colloidal nanometer sized particles forming an open porous structure. Phase change materials are those with high heat of fusion that could absorb and release a large amount of energy at the time of phase transition. These materials are mostly used as thermal energy storage materials but in addition they could serve as an obstacle for passage of heat during phase changes and this has led to their use in thermal protection systems. In this study، the effect of magnesium chloride hexahydrate، as a phase change material (melting point 115°C)، on thermal properties of carbon aerogels is investigated. Thermal performance tests are designed and used for comparing the temperature-time behavior of the samples. DSC is applied to obtain the latent heat of melting of the phase change materials and the SEM tests are used to analyze the microstructure and morphology of carbon aerogels. The results show that the low percentage of phase change materials in carbon aerogels does not have any significant positive effect on carbon aerogels thermal properties. However، these properties are improved by increasing the percentage of phase change materials. With high percentage of phase change materials، a sample surface at 300°C would display an opposite surface with a significant drop in temperature increases، while at 115-200°C، with carbon aerogels، having no phase change materials، there is a severe reduction in the rate of temperature increase of the sample.