Study on rheological behavior of Micro/Nano-silicon Carbide Particles in Ethanol by Selecting Efficient Dispersants.

Guoqiang Luo,Jian Zhang,Lianmeng Zhang,Jianian Hu,Qiang Shen,Zhuang Zhang,Yi Sun

doi:10.3390/ma13071496

Abstract

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.

Highlights

Silicon carbide ceramics are emerging candidates for special ceramics owing to their high hardness, high mechanical strength, high antioxidant capacity, and corrosion resistance
The technical characteristics of silicon carbide surface chemistry were determined by X-ray photoelectron spectroscopy (XPS) (ESCALAB 250Xi, Thermo Fisher Scientific, Shanghai, China) and Fourier transform infrared spectroscopy (FTIR) (Nicolet 6700, Thermo Electron Scientific Instruments, Shanghai, China)
The XRD peak (Figure 2) of the silicon carbide powder confirmed the existence of only the β–SiC

Summary

Introduction

Silicon carbide ceramics are emerging candidates for special ceramics owing to their high hardness, high mechanical strength, high antioxidant capacity, and corrosion resistance. Silicon carbide ceramics are widely used in the armor, aerospace, medical, chemical, steel metallurgy, and electronics industries, as well as other fields. Owing to the high strength and high brittleness of silicon carbide (SiC), the preparation of silicon carbide devices with complex sizes is limited, which increases the economic cost in their subsequent processing [1,2,3,4,5]. Colloidal processing, such as slip casting and tape casting, has been widely used to produce special ceramics from SiC powders [6,7,8,9]. It is important to obtain ceramic suspensions with good dispersion

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Conclusion