Effect of impurities on characteristics of ZrO₂ and ZnO ceramic powders produced by spray pyrolysis

Previously it was observed that addition of impurities to a precursor solution may alter the size and morphology of the particles produced by spray pyrolysis. To investigate this further, the spray pyrolysis technique was used to prepare zirconia (ZrO₂) and zinc oxide (ZnO) ceramic powders, with addition of slight amounts of NaCl in various concentrations. The results show an increase in the percentage of nondisrupted particles which corresponds to an increase in the weight percentage of NaCl in the precursor in ZrO₂ powder produced at 400 °C. This effect is not repeated in ZnO powder produced at 400 °C, as the addition of NaCl to the precursor results in the disruption of individual particles into much smaller particles. As far as the morphology and strength of particles are concerned, it is concluded that the addition of NaCl to the precursor solution has a beneficiary effect on the morphology of ZrO₂ particles and an adverse effect on ZnO particles, both of which are negated at a higher reactor temperature of 600 °C.