EFFECT OF Li5AlO4 ADDITIONS ON THE SINTERING AND PROPERTIES OF MAGNESIUM ALUMINATE SPINEL
Keywords:
Magnesium aluminate spinel, Li5AlO4, hot isostaticpressing, sinteringAbstract
Magnesium aluminate spinel (MgAl2O4) with high transparency has been wildly used in various applications because of its high mechanical strength and good optical properties. The aim of this work is to evaluate the effects of an additive, Li5AlO4, on the sinterability of MgAl2O4. The concentrations of Li5AlO4 focused in this study were 1, 5, and 10 wt%. An aqueous solution of Li5AlO4 was prepared by the reaction between high purity lithium nitrate and aluminium nitrate. Under the magnetic stirring at 60oC, MgAl2O4 powder (Baikalox, S30CR) was homogeneously added into the solution. The obtained viscous slurries were then dried, ground, sieved, and uniaxially pressed under 50 MPa. The green bodies were sintered in air at atemperature of 1600oC. It was found that, for the 1 wt% Li5AlO4 added specimens sintered at 1600oC, the relative density reachedup to 99.47%. The pre-sintered specimens were subjected tohotisostaticpressingat 1500oC for 1 h. Phase compositions, microstructures, and bulk densities of the sintered and HIP specimens were also characterized and discussed.
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