Nobuyuki Koike

Mesophase pitch and phenolic resin blends as binders for magnesia–graphite bricks

Abstract Naphthalene-derived mesophase pitch (NMP) and phenolic resins of novolac type and resol type were applied for the binder of MgO–C brick. NMP provided a brick of high strength at over 1000°C and high oxidative resistivity, however, the apparent porosity of the brick was high because of NMPs expansion at the carbonization. Both types of resins provided bricks of high strength and low apparent porosity at low temperature, the strength seriously decreasing over 1000°C. A blend of NMP and the resins provided bricks of excellent performance with high strength and low apparent porosity in a wide temperature range and high oxidative resistivity. The thermosetting resin bound MgO around 100°C and surrounded the dispersed NMP particles to prevent expansion at the latter carbonization, while NMP-originating carbon moderated the strong shrinkage of the resin over 1000°C, maintaining the high strength and density of the brick in a wide temperature range.

Densification of carbons prepared from mesophase pitch and phenolic resin blend

Co-carbonization of naphthalene-derived mesophase pitch (NMP) and novolac-type phenolic resin (NV) was investigated to densify the carbon derived from the mesophase pitch. Blending both types of phenolic resin to NMP suppressed the expansion during carbonization to densify the resultant carbon. Thermosetting NV before the carbonization of NMP fixed the molten pitch in the crosslinked network, suppressing the expansion of NMP. Blending in THF before the carbonization was effective in making the region of NMP smaller, leading to higher bulk density and finer mosaic texture of the resultant carbon. The carbon yields of the blend were lower than those expected from the additivity line. A large amount of naphthenic hydrogen of NMP is released to react with phenolic OH to prevent crosslinking and decompose phenolic resin. The air blowing of NMP drastically decreased its aliphatic hydrogens, increasing the carbon yields and the bulk density of the blend.