Mesophase pitch and phenolic resin blends as binders for magnesia-graphited bricks

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 degrees C and high oxidative resistivity, however, the apparent porosity of the brick was high because of NMP's 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 degrees 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 degrees 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 degrees C, maintaining the high strength and density of the brick in a wide temperature range. (C) 1999 Elsevier Science Ltd. All rights reserved.