Effect of mixing procedures and compaction pressures on the powder reaction of CuO-η-Al₂O₃ and ZnO-η-Al₂O₃ systems

Abstract

The rate of reaction of the compacted powders of CuO-η-Al₂O₃ and ZnO-η-Al₂O₃ systems was measured in air at 800 to 900° C and the effect of the mixing procedure (dry and wet mixing) and compaction pressure (0 to 8.3×10⁸ Pa) of reactant oxides on the fraction of reaction completed (α) was investigated. In the reaction of the CuO-η-Al₂O₃ system, the α-values obtained for the sample prepared by wet mixing in ethanol were higher than those for the sample prepared by dry mixing in air and were not influenced by the compaction pressure, whereas in the case of dry mixing they varied with the compaction pressure and had a maximum value at 2.1×10⁸ Pa. On the other hand, in the reaction of the ZnO-η-Al₂O₃ system the α-values for the sample obtained by wet mixing were lower than the values obtained by dry mixing, in contrast to the results in CuO-η-Al₂O₃ system, and the α-values for the samples prepared by both dry and wet mixing were not influenced by the compaction pressure. The effect of mixing procedure and compaction pressure of reactant powders on the α-values was found to be explained on the basis of the aggregate size of CuO and ZnO dispersed in the matrix of η-Al₂O₃ fine powder.