Densification of Magnesium Aluminate Spinel Using Manganese and Cobalt Fluoride as Sintering Aids

Highly dense magnesium aluminate spinel bodies are usually fabricated using pressure-assisted methods, such as spark plasma sintering (SPS), in the presence of lithium fluoride as a sintering aid. The present work investigates whether the addition of transition metal fluorides promotes the sintering of MgAl₂O₄ bodies during SPS. At the same time, such fluorides can act as a source of optically active dopants. A commercial MgAl₂O₄ was mixed with 0.5 wt% of LiF, MnF₂, and CoF₂ and, afterwards, consolidated using SPS at 1400 °C. Although MnF₂ and CoF₂ promote the densification as effectively as LiF, they cause significant grain growth.