The Preparation And Performance Of Mesophase Pitch-based Carbon Foam

With the development of science and technology, materials with high performance are required. Recently, carbon foams become attractive for many aerospace and industrial applications, due to their high thermal conductivity, low thermal expansion coefficient, low density, open porosity and chemical resistance. In this paper the preparation and properties of carbon foams from mesophase pitch are addressed.Three methods for preparation of carbon foams are adopted in this paper, i.e. pitch self-foaming process; starch-assisted foaming process and mesophase pitch foaming process modified by Fe(NO₃)₃. It has been found that the cell structure of carbon foams prepared with the pitch self-foaming process and the mesophase pitch foaming process modified by Fe(NO₃)₃ is more ideal than those obtained using the starch-assisted foaming process. On basis of the experimental results, the influence of process parameters on cell structure of carbon foams is discussed.The products are characterized using scanning electron microscopy (SEM), thermal gravity (TG), X-ray diffraction technique (XRD), and IR spectroscopy. At the same time, NOx analyzer is used for analyzing the decomposition behavior of Fe(NO₃)₃ mixed with and without mesophase pitch.The results also show that mesophase pitch with a suitable composition is a good precursor for making carbon foams. It is possible to prepare carbon foams with high performance and low cost using the methods adopted in this paper. Compared with the pitch self-foaming process, the starch-assisted foaming process and the mesophase pitch foaming process modified by Fe(NO₃)₃ result in carbon foams with ideal cell structures. Carbon foams treated by phosphate impregnation show great improvements in oxidation resistance.