Influence of the number of impregnation stages on the macrostructural and strength characteristics of glassy carbon foams

Abstract

The template synthesis of glassy carbon foams was used in the work and the influence of the initial template cell size, the concentration of the solution, and the number of impregnation stages on the macrostructural and strength characteristics of the obtained materials was studied. As a carbon precursor was used the solution of Novolac resin grade SFP-012A2, the coke residue of which is more than 57 wt. %. It was shown that increasing the number of impregnation stages makes it possible to improve strength characteristics while maintaining open porosity at the level of 90 %, while glassy carbon foam based on a polyurethane template with a porosity of 60 pores per inch and 4 stages of impregnation with a solution with a concentration of 30 wt. % has the best set of properties due to the uniform wall thickening in the material volume. The value of compressive strength was 1.12 MPa, which is 2 times higher than the value of foreign analogues, while the open porosity was 91 %. It has been established that a decrease in the size of the cells of the initial template can lead to embrittlement of the material due to the formation of a cluster of overlapped cells. Increasing the mechanical strength of glassy carbon foams while maintaining an open-cell structure expands the field of application of this class of materials.