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Study on Rheological Behavior of Micro/Nano-Silicon Carbide Particles in Ethanol by Selecting Efficient Dispersants

State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
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Materials 2020, 13(7), 1496; https://doi.org/10.3390/ma13071496
Received: 8 February 2020 / Revised: 9 March 2020 / Accepted: 16 March 2020 / Published: 25 March 2020
(This article belongs to the Special Issue SiC Materials and Applications)
A colloidal stability study of a nonaqueous silicon carbide suspension is of great significance for preparing special silicon carbide ceramics by colloidal processing. In this paper, three different chemical dispersants, which are amphiphilic, acidophilic, and alkaliphilic, are selected to compare their ability to stabilize nonaqueous slurries of silicon carbide. The analysis of the flow index factor is first used to estimate the colloidal stability of the suspensions. The results show that the addition of only 5 wt.% polyvinylpyrrolidone (PVP) forms a silicon carbide slurry with a low viscosity value of 17 mPa⋅s at 25 s−1. In addition, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS)measurements indicate that the PVP molecule is successfully adsorbed on the surface of silicon carbide. The different adsorption models are fitted, and the adsorption of PVP molecules on the surface of silicon carbide belongs to the Langmuir single-layer adsorption model. At the optimal PVP amount, the volume content of the suspension is as high as 22.27 vol.%, a Newtonian-like fluid still appears, and no agglomerate structure is formed in the system. After the volume content exceeds 22.27 vol.%, the flow index factor of the slurry begins to plummet, indicating that the slurry begins to transform from a Newtonian-like fluid to a shear-thinning fluid. The particles undergo inevitable agglomeration accompanied by the emergence of yield stress. Finally, a maximum solid loading of the system is predicted to be 46 vol.%, using the Krieger-Dougherty model. View Full-Text
Keywords: rheology; SiC suspension; colloidal stability; dispersion mechanism; flow index factor rheology; SiC suspension; colloidal stability; dispersion mechanism; flow index factor
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Luo, G.; Zhang, Z.; Hu, J.; Zhang, J.; Sun, Y.; Shen, Q.; Zhang, L. Study on Rheological Behavior of Micro/Nano-Silicon Carbide Particles in Ethanol by Selecting Efficient Dispersants. Materials 2020, 13, 1496.

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