Papers by Author: Ti Zhuang Wang

Abstract: SiAlON family matrix materials have been fabricated from nonmetallic mine. The process of Carbothermal Reduction and Nitridation (CRN) is selected on the basis of raw rocks containing various Si/Al ratios. Thermodynamic analysis of Si-Al-O-N system at different sintering temperatures indicates once the temperature is above 1673 K, a series of chemical reactions occur in sequence, SiO2, SiO, Si2N2O, SiO2+Al2O3, mullite, X-SiAlON, O′-SiAlON, β-SiAlON, SiAlON- polytypiods and Si3N4+AlN. Moreover, most of the reactions are exothermal and are promoted by further heating. The adding or in-situ formed SiC can reduce mullite and Al2O3 to produce O′- or β-SiAlON, and its reaction is surprisingly endothermic and is inhibited when further heated. Also, atmosphere is essential to affect the sintering process. Either raising N2 partial pressures or reducing CO partial pressures can accelerate CRN progress. Correspondingly, phase content and microstructure of the product converted from nonmetallic ore are in detail investigated via X-ray diffraction (XRD) and scanning electron microscopy (SEM).

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.