Microstructure of kaolin spheres produced by a gel‐casting process with a biopolymer additive

Abstract

Over the past few years due to increased environmental awareness, there has been great interest in improving ceramic processing to reduce the use of organic solvent and synthetic binders. This work is focused on a gel-casting process using a biopolymer that is environmentally friendly, easy to burn out and inexpensive. Starch was employed as a binder and kaolin clay was used as the starting material. To fabricate kaolin spheres, aqueous kaolin slurry was mixed with a starch solution. A small volume of the kaolin-starch solution was added to a vegetable oil at high temperature. The starch then formed a strong, cross-linked gel and immobilized the clay powders into the desired spherical shape. The kaolin spheres were then dried and sintered at different temperatures for 1 h. The phases present in the spheres was identified by X-ray diffraction (XRD) analysis. The microstructure and dimensions of the kaolin spheres were examined using a field emission scanning electron microscope (FE-SEM) in conjunction with energy dispersive spectrometry (EDS). An image analysis technique was used to identify the pore volume of the spheres.

Starch consolidation of alumina: Fabrication and mechanical properties

“…Origin of agglomerates can be due to incomplete dispersion of ceramic particle or incomplete dissolution of gelling agent in the solvent medium. Chumnanklang et al 32 reported that for higher starch content, the gelled starch occupies a larger space between the particles.…”

Linear Shrinkage, Strength and Porosity of Alumina-Based Ceramic Foam with Corn Starch as Pore Former

“…The results showed that porosity linearly increased with increasing starch content. According to Chumananklang et al [11], the gelled starch with higher starch content occupies a larger space between particles. Larger pores cannot be eliminated after the binder burnout step and hence results in a higher porosity.…”