Structure and Properties of High-Strength Hard Carbon Foams Prepared by SiO2 Porosity-based Method
Due to the limitations of raw materials and preparation processes,the strength of phenolic resin-derived carbon foams is very low,which limits their applications.In this paper,a series of high-strength carbon foams with different porosities were prepared by template porosimetry with phenolic resin as the carbon source and SiO2 powder as the porosimetry agent,and the effects of different contents of SiO2 on their microstructure,mechanical properties,and thermal conductivity were investigated.The results show that with the increase in SiO2 content,the porosity of carbon foams increases and the bulk density decreases.The compressive strength decreases as the density decreases,and the highest compressive strength is 79.7 MPa when the ratio of resin to SiO2 is 3∶1.When the ratio changes from 3∶1 to 1∶2,the density of the carbon foam declines from 0.691 g·cm-3 to 0.287 g·cm-3,and the compressive strength decreases from 79.7 MPa to 23.8 MPa.And carbon foam with a density of 0.287 g·cm-3 has a lower thermal conductivity(0.223 W·m-1·K-1),which is expected to be a high(specific)strength lightweight thermal insulation material.
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