Direct coagulation casting of nano-8YSZ powder suspensions using nano-MgO as coagulating agent

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• 作者：Leandro Pelegrini^a ; ^{le_pelegrini@yahoo.com.br" class="auth_mail" title="E-mail the corresponding author} ; Luiz Eloi Vieira Junior^b ; ^{eloi_junior@hotmail.com" class="auth_mail" title="E-mail the corresponding author} ; Joã ; o Batista Rodrigues Neto^c ; ^{joao.neto@ufsc.br" class="auth_mail" title="E-mail the corresponding author} ; Dachamir Hotza^d ; ^{d.hotza@ufsc.br" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Nano-8YSZ ; Nano-MgO ; Direct coagulation casting (DCC) ; Colloidal processing ; Nanosuspension rheology ; Colloidal stabilization
• 刊名：Ceramics International
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：43
• 期：1
• 页码：316-323
• 全文大小：1848 K

文摘

New colloidal techniques such as direct coagulation casting (DCC) arise to manufacture dense, homogeneous and nanocrystalline advanced ceramics. In this work, it was possible to obtain a high solid content (72 wt%) aqueous suspension from nano-8YSZ (15–50 nm) using a suitable PAA-NH₄ dispersant. Moreover, coagulation was reached by increasing ionic strength mechanism, with an optimized amount of 0.25 wt% nano-MgO (~20 nm) maintaining a low initial viscosity (~60 mPa s at 100 s⁻¹), which corresponds to a suitable rheological behavior for direct casting. An attenuated coagulation rate was found, along a 30-min window process, due to the nanosized MgO particles. The nanosuspension was then successfully cast into a non-porous PVC mould at 25 °C producing a dense structure without cracks after 6 h. High density (~96% T.D.) samples were obtained at 1350 °C/5 h with mean grain sizes of ~800 nm and a cubic phase corresponding to 8 mol% Y₂O₃ according to XRD analysis.