Densification and grain growth of nano- and micro-sized Y-TZP powders

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• 作者：Alexandre Alvarenga Palmeira^a ; ^b ; Marcelo José ; Bondioli^c ; Kurt Strecker^c ; Claudinei dos Santos^a ; ^b ; ^{claudinei@pesquisador.cnpq.br" class="auth_mail" title="E-mail the corresponding author}
• 关键词：A1. Grain growth ; A2. Sintering ; ZrO2(3%Y2O3) ; Nano-sized powder ; Microstructure
• 刊名：Ceramics International
• 出版年：2016
• 出版时间：1 February 2016
• 年：2016
• 卷：42
• 期：2
• 页码：2662-2669
• 全文大小：1519 K

文摘

In this work, the sintering of nano- and micro-sized yttrium stabilized zirconia powders, ZrO₂-3 mol% Y₂O₃, has been compared. The finer powder exhibited an average particle size of 0.15 µm, a crystallit e size of 40 nm and a specific surface of 16.2 m²/g, while the micro-sized powder had a particle size of 0.68 µm, crystallite size of 120 nm and a specific surface of 7.0 m²/g. Cold uniaxially pressed samples of the nano-sized powders were sintered at temperatures between 1250 and 1400 °C, while samples of the micro-sized powders were sintered at temperatures up to 1600 °C. Furthermore, the influence of isothermal holding times varying between 2 and 16 h has been studied. The nano-sized ZrO₂ powders achieved almost complete densification at a temperature as low as 1350 °C, while the micro-sized powders reached similar densification only after sintering at 1530 °C. The average grain size of samples prepared from the nano-sized powders increased from 0.18 µm, when sintered at 1250 °C without isothermal holding time, to 0.64 µm when sintered at 1400 °C for 16 h. In the case of micro-sized powders the average grain size varied between 0.40 µm, when sintered at 1530 °C without isothermal holding time, and 1.84 µm when sintered at 1600 °C for 16 h. From the results of the quantitative microstructural analysis, grain growth exponents of 2.8 and 2.3 were calculated for the nano- and micro-sized starting powders, respectively. The value of the activation energy was determined to be 141.3 kJ/mol for the nano-sized powders. Moreover, the much smaller initial particle size of the nano-sized powders results in a significant reduction of the sintering temperature of approximately 160 °C. Samples prepared from these powders reached almost full density at 1400 °C without further isothermal holding treatment, exhibiting an extremely fine grained and homogeneous microstructure, with an average grain size of 0.22 µm.