Effect of Ammonium Polyacrylate and Pre-Oxidation on Rheological Properties of Si₃N₄ Slurries

E-ISSN： 1662-9752|2015|816|102-106

ISSN： 0255-5476

Source： Materials Science Forum, Vol.2015, Iss.816, 2015-05, pp. : 102-106

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Abstract

The key for gel-casting is the preparation of ceramic aqueous slurries with excellent rheological properties. The effect of ammonium polyacrylate and pre-oxidation on rheological properties of Si₃N₄ slurries was investigated. The Si₃N₄ isoelectric point (IEP) is between 3 and 4 in premix solution and particle surface potential is maximum at pH between 9.5 and 10.5. PAA-NH₄ of dispersant can obviously decrease the viscosity of Si₃N₄ slurries, and the optimal dosage is about 1.6wt% of Si₃N₄ powders. Meanwhile, the Si₃N₄ slurries exhibit pseudoplastic fluid with the characteristic of shear-thinning behavior. Due to the improvement of powder surface characteristic, the pre-oxidation significantly improve the rheological properties of the Si₃N₄ slurries.