Papers by Author: Rui Sheng Wang

Abstract: Zirconyl chloride was used as zirconium source and fused silica particles were used as main raw material. First of all, the composite powders were prepared by wet chemical synthesis using ammonia as the precipitator and polyethylene glycol as the dispersant. Then, fused silica nanozirconia composite ceramic containing nanometer particle zirconia with different contents (5%, 15%, 25% and 35%) were fabricated in reduction atmosphere at 1300°C, 1350°C and 1400°C for 1 h. The bulk density and bending strength were measured, microstructure was observed by SEM. The result indicated bulk density and bending strength of composite ceramic increase and microstructure becomes denser with content of zirconia increasing. Bulk density of composite ceramic increases and bending strength which reaches maximum at 1350°C firstly increases then decreases with the increase of sintering temperature. Both high sintering temperature and nanozirconia possessing high energy interface can improve the composite ceramic sintering.

Abstract: Fused silica particles and zirconyl chloride were used as main raw material. Meanwhile, ammonia was used as precipitator and polyethylene glycol as dispersant. Firstly, the composite powders were prepared by wet chemical synthesis. Then, fused silica/zirconia ceramic composites containing zirconia with different contents (5%, 15%, 25%, 35% and 45%) were fabricated in reduction atmosphere at 1300°C, 1350°C and 1400°C for 1 h. The thermal expansion ratios and XRD of samples were examined. The analysis of XRD indicated that the cristobalite peaks intensity of sample with more zirconia is lower at the same sintering temperature, and the intensity of cristobalite was higher while sintered at higher temperature. Zircons were found in all samples’ XRD patterns. The results of thermal expansion ratios showed the ratios of samples with more zirconia were lower, especially at higher sintering temperature. So, existence of zirconia can inhibit crystallization of fused silica/zirconia ceramic composites effectively.

Abstract: AlN powders were prepared via carbothermal reduction-nitridation of nonhydrolytic Al₂O₃ gels. The XRD results showed that only AlN phase formed when the sample was calcined at 1450 °C in N2 flow of 80 ml/min, which was lower than that using Al₂O₃ powders as starting materials. The AlN powders were near-spherical particles and their particle size was around 400 nm. The effect of the CaF₂ addition on the synthesis of AlN powders was aslo investigated. The results showed that the synthesis temperature of AlN powders colud decrease to 1400 °C, when 3wt% of atalytic agent CaF₂ was added. Meanwhile, the particles size of AlN powders decreased, but their size distribution became wide range.

Abstract: β-Sialon bonded ZrO₂ composites were prepared by reaction sintering process using β-Sialon and CaO stabilized ZrO₂ powders as raw materials.The effect of β-Sialon powder additions on the properties of the composites was investigated. The results show that the samples with 10 wt% of β-Sialon addition had the lowest apparent porosity (29.80%) and the highest of flexural strength (68.70MPa). The thermal shock resistance in carbon addition of the composites could be improved by addtion of 5wt% β-Sialon. It may be relative with that the sample had the lowest thermal expansion coefficient in vacuum.

Abstract: The characteristics of grouting material for blast furnace lining crack repair were briefly introduced in this paper. The influences of matrix aggregates particle size grades on the properties of grouting materials for blast furnace lining crack repair were mainly discussed. Based on series of tests and experiments, the optimized matrix aggregates particle size grades were confirmed.

Abstract: Fused quartz granule (d₅₀=0.019 mm) was used as raw material, nano-ZnO (size<0.08 μm) was used as additive with dosages of 1% (in mass, similarly hereinafter), 2% and 3%. Fused quartz ceramic materials were fabricated in reduction atmosphere at 1300 °C, 1350 °C and 1400 °C for 1 h. Properties of samples were researched by measurements of apparent porosity, bending strength and thermal expansion rate, and analyzed by XRD and SEM. The results showed that additive nano-ZnO had excellent inhibiting effect on crystallization of fused quartz sintered at 1300 °C and 1350 °C. As dosages of nano-ZnO increased, thermal expansion rate, diffraction peak intensity and bending strength were improved, and microstructure of the samples became more compact. It can be deduced that for fused quartz ceramic materials, with add dosage of nano-ZnO increasing, the inhibiting effect on crystallization decline, but the facilitating effect on sintering enhance.

Abstract: An easy synthesis route of YSZ (Yttria-Stabilized Zirconia) nanopowder with the formation of Zr_0.92Y_0.08O_1.96 is synthetized by using thermal decomposition of ZrOCl₂ and Y(NO₃)₃, with polyvinyl alcohol (PVA) as surface active agent and with quantitative filter paper as carrier. The roasting temperature of YSZ precursor was 650oC. The results of SEM and XRD analysis showed that the pure ZrO₂ and YSZ powders prepared via thermal decomposition had better crystallinity, and YSZ powders had perfect crystalline t-ZrO₂ phase after heating at 650 °C, and changing the amount of PVA or the reaction precursors could obtain YSZ powders sized 20-50 nm.

Abstract: Fused quartz powder (size<0.04mm) was used as raw material, nano-Y₂O₃, nano-CeO₂ and nano-La₂O₃ (size<0.08μm) were dividedly used as additives with dosage of 2% each. Fused quartz ceramic materials were sintered in reduction atmosphere at 1300°C, 1350°C and 1400°C for 1h. The effect of rare earth nano-oxides on sintering and crystallization of the fused quartz ceramic were researched by measurements of apparent porosity, bending strength and thermal expansion rate, and analyses of XRD and SEM. The results showed that additives nano-Y₂O₃, nano-CeO₂ and nano-La₂O₃ had obvious effect of inhibiting crystallization of fused quartz, and the samples added nano-Y₂O₃ and nano-La₂O₃ were better. Sample added nano-Y₂O₃ had least thermal expansion rate. Sample added nano-La₂O₃ had higher bending strength, and it showed that nano-La₂O₃ had better effect on sintering of fused quartz ceramic. It can be deduced that nano-La₂O₃ plays the excellent role as the crystallization inhibitor of fused quartz materials.

Abstract: Fused quartz granules (d₅₀=19 μm) were used as raw material, and B₄C-Yb₂O₃ (1:1, in mass) was used as additive with dosages of 1% (in mass, similarly hereinafter), 2% and 3%. Fused quartz ceramic materials were fabricated in reduction atmosphere at 1250 °C, 1300 °C, 1350 °C and 1400 °C for 1 h. The apparent porosity, bending strength and thermal expansion ratios of the samples were examined and they were analysed by means of XRD and SEM. The results showed that the sample sintered at each temperature with 3% B₄C-Yb₂O₃ had the lowest apparent porosity, the highest bending strength and more compact microstructure. This indicated that 3% B₄C-Yb₂O₃ was conducive to sintering of fused quartz ceramic materials. The results of XRD analysis and thermal expansion ratio analysis showed that 3% B₄C-Yb₂O₃ compound additive had obvious effect on inhibiting crystallization of the samples sintered at various temperatures. It can be deduced that the 3% B₄C-Yb₂O₃ compound additive plays the excellent role in inhibiting crystallization and facilitating sintering of fused quartz ceramic materials.

Abstract: Fused quartz granule (d₅₀=0.019 mm) was used as raw material, nano-Y₂O₃ (size<0.08 μm) was used as additive with dosages of 1% (in mass, similarly hereinafter), 2% and 3%. Fused quartz ceramic materials were fabricated in reduction atmosphere at 1300 °C, 1350 °C and 1400 °C for 1 h. Properties of samples were researched by measurements of apparent porosity, bending strength and thermal expansion rate, and analyzed by XRD and SEM. The results showed that additive nano-Y₂O₃ had good inhibiting effect on crystallization of fused quartz sintered at various temperatures, sample added 2% nano-Y₂O₃ had least thermal expansion rate, diffraction peak intensity and apparent porosity, and it had higher bending strength and more compact microstructure, especially sample sintered at 1350 °C. It can be deduced that 2% nano-Y₂O₃ plays the excellent role as the crystallization inhibitor and sintering assistant to fused quartz materials sintered at various temperatures.