Effect of compositional variation on the synthesis of magnesite–chrome composite refractory

Magnesite–chrome composites have been prepared by utilizing sintered magnesite and friable chrome ore in presence of titania as additive. Three types of batch compositions containing 5% Cr2O3, 18% Cr2O3 and 30% Cr2O3 have been selected for developing mag–chrome composites. The aggregates were developed by first vibro milling the raw materials and then additives were incorporated in wt.% along with 5% PVA solution as binder to the different batches. It was then properly mixed by fluidized bed mixer and after sieving in 20-mesh BS sieve briquettes were formed uniaxially at a pressure of 100 MPa. The briquettes were first air dried and subsequently oven dried at <F>110±5</F> °C for 24 h. Finally, the green briquettes were fired at 1700 and 1750 °C in electrically program controlled muffle furnace. The physical properties as well as thermo-mechanical properties and microstructural studies of the sintered aggregates have been evaluated. The common feature observed in the microstructures is the exsolution of spinel phase in magnesia grains. The hot properties of the composites are superior when the Cr2O3 content is increased to 30%. Additives played a significant role in improving the bulk density and strength. [Copyright &y& Elsevier]