Papers by Author: Shu Yu Yao

Abstract: The glass ceramics bricks were prepared by the method of isostatic pressing and one time sintering using fly ash and glass powder as raw materials. X-ray diffraction experiment was performed to identify the main crystal phase. The influence of sinter temperature on the hardness was studied. It was concluded that the main phase were anorthite and albite. The hardness of sample which contains 60% of fly ash attains 766.79MPa when the sintering temperature was 1110°C .The hardness of sample which contains 50% of fly ash attains 780MPa when the sintering temperature was 1075°C.

Abstract: A new glass-ceramic coating material on nickel based super alloy substrate had been found, the glass¬-ceramic coating material was developed from a glass based on MgO–Al2O3–TiO2 system. The coating material was characterized through X-ray diffractometry (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), hardness, thermal expansion coefficient testing. XRD analysis of the coating materials and the resultant coatings showed presence of a number of microcrystalline phases. SEM micrographs indicated microstructure of the material. Optical micrographs showed smooth glossy impervious free surface with defects. Hardness analysis showed the glass-ceramic coating material had higher microhardness. The thermal expansion coefficient of the nimonic alloy was much higher compared to the coating material at specific temperature.

Abstract: A novel wear resistant glass-ceramic coating system (based on SiO₂-B₂O₃-Al₂O₃ glass system) on iron based substrate was developed. Friction coefficient, wear rate and coefficient of thermal expansion of coating material were evaluated using suitable methods. The coating materials and the resultant coatings were characterized using differential thermal analysis (DTA), X-ray diffraction analysis (XRD) and Scanning Electron Microscope (SEM). XRD analysis of the coating materials showed presence of a number of microcrystal. SEM micrographs indicate strong chemical bonding at the iron-ceramic interface. The coating material showed perfect properties for protection the iron substrate from abrasion.

Abstract: The Fe2O3-CaO-SiO2 glass ceramics were prepared by the method of quenching and controlled crystallisation. Differential thermal analysis, X-ray diffractometry and vibrating sample magnetometer were used to study the crystallisation and magnetic properties of Fe2O3-CaO-SiO2 glass ceramics. It was concluded that the main crystalline phases of glass ceramics during the process were Hematite, Iron Silico Oxide and Hedenbergite. The saturation magnetisation values (Ms) of glass ceramics varied between 108 emu•g-1 and 147 emu•g-1. The crystallisation of Hedenbergite lead to the high Hc value (~2000Oe).

Abstract: A theoretical procedure was developed with the aim of obtaining a rapid and accurate estimation of the degree of crystallization in glasses obtained from fly ash by measuring the dielectric constants. Compositions were prepared by melting the mixture of fly ashes, nucleators, fusing agents and clearing agents at 1500°C. Dielectric constant measurements were carried out by means of universal bridge. The results were compared with the degree of crystallization as evaluated by the method of density and showed a good agreement.