Papers by Author: Hua Zhi Gu

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Authors: Mei Jie Zhang, Hou Zhi Wang, Hua Zhi Gu, Ao Huang
Abstract: The resistance coefficients through which gas flow permeable refractory are important properties and have great effect on the gas blowing parameters and gas-liquid two phase flowing characteristics in the metallurgy furnace such as ladles, tundish. In this paper, the resistance coefficients were measured according to the Forchheimer’s law. The results show when the gas flow rate is fixed, the viscosity resistance coefficient and inertia resistance coefficient decrease as the apparent porosity and average pore diameter increase. The viscous resistance coefficient is more lager than the inertial resistance coefficient. The resistance coefficients were analyzed by dimensional analysis and the statistical correlations between the resistance coefficients and parameters of porous permeable refractory were got based on the experimental data. In order to get high strength at low resistance coefficients, the raw materials particle degree were adjusted.
Authors: Jing Jing Zhu, Hua Zhi Gu, Shu Feng Chen, Tian Xing Peng, Nai Peng
Abstract: The silica matrix specimens were prepared by adding microsilica and MoSi2 powder. The mixture were pressed to cylinder and then sintered at 1200oC, 1250oC, 1300oC and 1400oC for 8h respectively. The phase compositions of specimens were analyzed by X-ray diffusion and the tridymite crystal morphology and grain sizes were observed by SEM. The results show that with the addition amount of MoSi2 powders increase, the intensity of tridymite diffraction peaks first strengthen slightly and then decrease, becoming more and more amorphous process, while the diffraction peaks of residual quartz phase enhance. When adding 2.5% MoSi2, the precipitation of CaMoO4 phase reduces the O/Si ratio in the liquid phase, and promotes the generation of tridymite, so the number of tridymite increase, but the crystal size decreases. With the sintering temperature increase, the intensity of tridymite diffraction peaks increase, the residual quartzite amount reduces.
Authors: Hua Zhi Gu, Hou Zhi Wang, Yan Ruo Hong, Jia Lin Sun, Wen Jie Zhang
Abstract: Hydration resistance of three commercially available high-purity MgO-CaO clinkers were investigated and compared in the present paper. The results show that, as well as CaO content, microstructural morphology of MgO–CaO clinker affects its hydration resistance. The microstructure in which CaO is present at the grain boundaries of MgO leads to poorer hydration resistance, whereas the one in which CaO and MgO are distributed alternately confers much improved hydration resistance on the clinker, especially when MgO level is high enough to cover most of the CaO crystals.
Authors: Hua Zhi Gu, Rong Dan Shao, Wen Jie Zhang, Hou Zhi Wang, Kai Bao Yang, Shu Zhong Yu
Abstract: SiC whisker was produced through the reaction between carbon and silicon powders during the sintering of Al2O3-ZrO2-C materials. The thermodynamic conditions and growth mechanism were discussed. The results showed that rod-shaped and dumbbell-shaped SiC whiskers are formed, respectively. The main composition of the beads in dumbbell-shaped whisker is SiOX with a small amount of Na and Ca, but the rods are SiC. In addition, the dumbbell-shaped SiC whisker contributed less than straight rod-shaped SiC whisker to improving the physical properties of Al2O3-ZrO2-C materials.
Authors: Mei Jie Zhang, Hou Zhi Wang, Hua Zhi Gu, Ao Huang
Abstract: The Al2O3-mullite system porous refractories were fabricated, and then pretreated by sol-gel. The samples were sintered at 1200°C for 3 hours. The microstructures and phases of the samples were analyzed by SEM and XRD respectively. The physical properties of the samples were measured according to National Standard of Refractory. Mullite-whiskers were formed in the pores of the samples. The pretreated samples were more permeable, and were greatly strengthened.
Authors: Hua Zhi Gu, Ao Huang, Hou Zhi Wang
Abstract: According to the practical physical dimension and processing parameters of ladle with bottom gas blowing in a factory, a geometrical model was established and mesh structure was completed, Eulerian multiphase model and porous media model were adopted for the two-phase flow in ladle, which was coupled, the effect of temperature field and thermal stress in course of working process of permeable- gas refractory ceramic was studied by finite element approach. The correlations between processing, structure, and high-temperature mechanical properties were discussed, and the material and structure of permeable-gas ceramic were designed to optimum. The results show that: The steady gas flow rate can avoid wearing of permeable-gas refractory ceramic from cataclysm of temperature-stress; After the material and structure of permeable-gas refractory ceramic are optimized, the effect on ceramic wearing of temperature-stress in condition of oxygen washing is weakened. It is an important guiding for prepara- tion of permeable-gas refractory ceramic with long life, which will make for highly active refining ladle.
Authors: Hua Zhi Gu, Hou Zhi Wang, Jia Lin Sun, Wen Jie Zhang, Dong Zhi Hou, Cheng Ji Deng, Yan Ruo Hong
Authors: Chun Feng Wang, Hua Zhi Gu, Hao Chen
Abstract: Superfine nanometer SrTiO3 with size of near 50-60nm was prepared by citrate process and sol-gel method. XRD and TEM characterizations indicate that sol-gel method is appropriate to prepare high-purity powders at far lower temperature than other methods. The Ni-based catalysts were prepared by using SrTiO3 powder as support through impregnation and sol-gel method. These catalysts were applied to the reaction of CO2 reforming CH4 to synas and showed high activity. The catalytic activity of Ni-based catalyst is investigated by reaction temperature, the method of support preparation, and the method of catalyst preparation; It shows that the catalyst possesses higher catalytic activity with the increasing of temperature; and the catalytic rate is near 90% at 973 K; and the catalyst show higher catalytic activity when support is prepared by sol-gel method than by citrate process; and the catalyst shows better catalytic activity when catalyst is prepared by sol-gel method than by impregnation method.
Authors: Hua Zhi Gu, Hou Zhi Wang, Mei Jie Zhang, Ao Huang, Wen Jie Zhang
Abstract: The temperature distribution of the permeable brick was modeled using CFX software. The influence of magnesia and corundum on thermal shock resistance of non-cement bonded alumina-based permeable brick was investigated. The results indicated that, in the gas blow process, the high temperature regions near the working face of the brick gradually expanded with the increase of the gas flow rate. Therefore the inner part of the brick had the complex and large change of thermal stress. Further experiments demonstrated that thermal shock resistance of alumina-magnesia based castable refractory was better than that of alumina-chrome based castable refractory. With the increase of magnesia amount, the alumina-magnesia based castable refractory had more cycles of heating and water-cooling. When different kinds of corundum were added in the raw materials, the sample with tabular corundum showed the best thermal shock resistance, the one with white fused corundum performed worse and the one with fused dense corundum performed worst.
Authors: Chun Feng Wang, Fei Zhou, Hua Zhi Gu, Hong Xi Zhu, Ya Wei Li
Abstract: Crude vermiculite is used as raw materials, heat-treated for activation, leached with a complexing acid, exchanged with sodium solution, following contacted with polyhydroxyl aluminium solution. The Al-intercalated vermiculites are prepared by ion exchange. The phase and microstructure of the composite material are analyzed by means of XRD, TEM, TG-DSC, et al. The results reveal that the basal spacing of vermiculite expanded by intercalation of Al-species, and the interlayer of vermiculite inlaid with a large amount of nanometer Al-species particles.
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