The effect of pyrocarbon deposition on the microstructure of graphitic foam

Mesophase-pitch-based graphitic foams (MPGFs) were derived. Pyrocarbon (PyC) has been deposited on the inner surface of some MPGFs. Microstructures in the ligaments and nodes of MPGF, morphology of PyC and the boundary between MPGF and PyC have been investigated by transmission electron microscopy and related techniques. In MPGF, straight and compact graphitic crystallites within the long and thin ligaments extend along the bubble walls, while graphite sheets within the nodes are more disordered and less compact with many defects. A PyC reinforcement uniformly covered the inner surface and filled microcracks between graphitic sheets, and was almost perfectly bonded to the MPGF substrate even at the nanoscale. On the vertical side of MPGF, whose surface is perpendicular to (0 0 0 2) planes of graphite layers, some amorphous carbon was formed between MPGF and PyC on the boundary. On the parallel side with the surface parallel to (0 0 0 2) planes, PyC combines with MPGF surface directly and closely without any amorphous carbon.