The effect of oxide additions on the high-temperature properties of magnesia

The object of this research was to determine the effect of additions from the CaO–MgO–SiO2 ternary phase system on the sintering behaviour of high purity magnesia. This system was chosen because it was relevant to the production of commercial refractory material used in steel manufacture. Additions of forsterite, monticellite, merwinite, dicalcium silicate, tricalcium silicate and calcium oxide were made to magnesia, having a total impurity content of 27 p.p.m. This was specially prepared by calcining at 800°C magnesium oxalate obtained by chemical means from pure magnesium metal. Mixtures were sintered between 1400°C and 1800°C for times between 0.1 and 8 hours, and the kinetics of their densification and crystal growth followed. [Continues.]