Activated Synthesis and Sintering of Complex Spinel Bonded Basic Refractories

摘要

The single stage reactive sintering of magnesium aluminate and magnesium chromite spinels from its oxide constituents is difficult because of volume expansion during the sluggish diffusion-assisted formation. Chrome ore contains other spinel formers (Al_2O_3, Fe_2O_3) that change oxidation state and lead to single stage reactive sintering. Similarly, optimization of tetravalent cation oxides result in chrome-free spinel solid solution with controlled expansion because of intermediate phases. The effect of different oxides on structural inversion of spinel solid solution and sintering were studied so that magnesia-based, chromia-free spinel could be produced with reduced sintering temperature. The structure of spinel solid solution and volume expansion due to spinel formation during sintering lead to an understanding of activated synthesis, resulting in fabrication of reaction bonded magnesia-rich complex spinel as a matrix for basic refractories.