Papers by Author: Yi Gong

Abstract: The high performance coal gangue foam concrete with the dry density less than 440kg/m3, the thermal conductivity less than 0.085W/(m•K) and the compressive strength over 2.0 MPa was prepared. The microstructure of the coal gangue foam concrete was analyzed by SEM. The hydrates of the coal gangue foam concrete were detected by XRD, and the temperature stability of the coal gangue foam concrete was analyzed by DTA and DSC.

Abstract: The chemical composition and the valence state of elements on the surface of ZrO2 thin films deposited on glass substrates have been studied by X-ray photoelectron spectroscopy. Results show that: elements of Na, Mg, Zr, Ca exist in the form of their respective stable state, such as Na2O, MgO, ZrO2, CaO, when heat treated at 500°C for 0.5h; but Si is unstable, and exhibit stoichiometrical disturbances. Results of chemical composition and their content by atom percent of ZrO2 thin films surface reveal that: Si, and Ca diffuse from glass to the thin films in scale; Na diffuses few and Mg collects to the thin films surface. The diffusion of Mg2+ and Ca2+ from glass to ZrO2 thin films is negative diffusion.

Abstract: The influence of heat-treated temperature and the CeO2 content on the chemical composition and the valence state of elements on surface of ZrO2-CeO2 thin films deposited on metal substrates has been studied by X-ray photoelectron spectroscopy. Results show that: elements of Fe, Cr, Zr, Ce exist in the form of their respective stable state, such as Fe2O3, (Fe0.6Cr0.4)O3, ZrO2, CeO2, when heat treated at 600°C and 700°C for 2h respectively; with the increase of heat-treated temperature, the area of oxygen with O1s peak corresponding to value of bonding energy 529.28ev increases, but the area of oxygen with O1s peak corresponding to value of bonding energy 531.7ev decreases.

Abstract: A heated sprue device for ceramic injection moulding was used to research the defects in injection-moulded technical ceramics. By use of the heated sprue device, the problem of sprue solidification was resolved and the density of the injection moulding specimens was increased while the defects eliminated. The influence of the processing parameters on the defects of the injection molding specimens was investigated in detail by X-ray radiography camera and photograph. It turns that the sprue solidification time has much influence on the defects in injection-moulded technical ceramics. Reasons causing the results above were also analyzed. Based on the research, bars of 20mm in diameter without macroscopic defects and turbine blade of fine property with Si3N4/SiC(w) materials were prepared by injection moulding.

Abstract: According to the heat transmission theory, in the aid of computer, the temperature distribution in the cylinder cavity was calculated. The temperature of the mould has much influence on the time for the injection material’s temperature of the cavity center to drop to the injection material softening temperature. The influence of the processing parameters on the density of the injection molding specimens was also investigated. It turns that the injection molding specimens’ density changes little with the increase of injection temperature and pressure, but changes a lot with the increase of holding pressure time.