关键词: CaZrO₃, Co₂O₃, 烧结性能, 物相组成, 晶粒尺寸

Abstract:

CaZrO₃ specimens were prepared by the high-temperature solid state method using analytically pure ZrO₂ and Ca(OH)₂ as raw materials,adding different amounts of Co₂O₃ (0,0.5%,1.0%,1.5% and 2% by mass),batching,molding,drying and firing at different temperatures (1 500,1 550 and 1 600 ℃ for 3 h).The results show that as the Co₂O₃ addition increases,the bulk density,the linear shrinkage and the average grain size of the prepared CaZrO₃ first increase and then decrease,while the apparent porosity changes in the opposite trend.CoO from the decomposition of Co₂O₃ has infinite displacement reaction with CaO,which reduces the activation energy of the reaction between CaO and ZrO₂,thus promoting the densification of the specimens.However,when the Co₂O₃ addition exceeds 1.5 mass%,more O₂ is produced during the decomposition of Co₂O₃,and the generated CoO cannot solid-dissolve with CaO crystals in a short time,which hinders the direct contact of reactants in the grain boundaries thus reducing the sintering performance.Therefore,the optimal addition of Co₂O₃ is 1.5 mass%,and in that case,the specimen has 4.25 g·cm^-3 of bulk density,3.3% of apparent porosity,and 6.13 μm of CaZrO₃ average grain size.

Key words: calcium zirconate, dicobalt trioxide, sintering property, phase composition, grain size