Effects of the Roughness of Graphite Substrate on the Properties of Pyrolytic Graphite

Abstract

The Research Institute For Iron, Steel and Other Metals. Tohoku University. Effects of the roughness of graphite substrate on the properties of pyrolytic graphite have been examined. Pyrolytic graphite is obtained by pyrolysis of commercial propane gas at the deposition temperature of 2025°C, the pressure of 10mm Hg and the flow rate of 640cc/min by direct heat method. The three kinds of roughness of the substrates are obtained using of abrassive papers (05, 280). The effects are not remarkable as compared with that of the deposition temperature and gas pressure, but can not be ignored. In the case of the smooth surface (abrassive paper 05), the surface of the deposit is smooth and the microstructure is fine, in which the crack does not appear. Furthermore, the formation rate is large, the ordering is good and the preferred orientation is remarkable. But in the case of the rough surface, the above mentioned phenomena tend to appear in the reverse side. Especially, the electrical resistivity of c-axis in the smooth case is about 10per cent higher than that of the rough surface. However, there are inconsiderable difference in the lattice constant and density between the smooth and rough surfaces.