Papers by Author: Yun Yao

Abstract: Based on the slip casting and the preparation of sialon synthesized from clay, fly ash and gangue by the carbothermal reduction nitridation, the influences of compositions, dispersant additive and sintering process on the properties of materials have been investigated in present work. The experimental results indicate that disposal of fly ash via a pickling process can greatly reduce the content of iron, and the effect is obvious with increasing the concentrations of hydrochloric acid and pickling temperature. Therefore the component of the final product can be purified. It is also noted that the final density of the sintered body using colloidal process is superior to that of using conventional dry pressing, although the slightly higher green density is observed in dry pressing body because of high compaction pressure.

Abstract: Green compact containing Yellow River sand and several additives was prepared by slip casting and the as-made compact was used to synthesize SiAlON multiphase ceramics by carbothermal reduction nitridation. The processing parameters of slip casting including the type and concentration of dispersant, solid loading, ball milling time, pH value and particle size distribution were optimized by orthogonal experiments. The results indicated that the raw materials could disperse uniformly in the suspension under the use of the mixed dispersant of skip liquid (SL, PT) and sodium carboxymethylcellulose (CMC). The green body with high bulk density of 1.86 g·cm-3 was obtained. After sintered in flowing N2, the compact could transform to SiAlON multiphase ceramics.

Abstract: Carbon-containing refractories are widely used in metallurgical industry due to their excellent thermal property and resistance to corrosion by molten iron. In the present work, slip casting colloidal process, which is used to fabricate high performance structural ceramics, has been introduced into the preparation for magnesia-carbon refractory with selection of suitable dispersant. The results indicated that the curve of zeta-potential of magnesia was similar with that of carbon just containing dispersant and the homogenized mixtures were attained under a controlling of low pH value. Three kinds of preparing routes for green bodies were designed, and all of the final densities and the resultant hardness of sintered bodies using colloidal process were superior to these of the specimen using conventional dry pressing, whereas its high green density can be plausibly observed in dry pressing body because of high compaction pressure used.