CERAMICS INTERNATIONAL
·
2020
·Vol. 46
·期 15
·24204-24212
·
IF 3.83
Yang Liu,Xiangcheng Li,Guoping Wei,Pingan Chen,Boquan Zhu
The effects of in-situ synthesis columnar mullite and pore structure on the hot modulus of rupture (HMOR), thermal shock resistance and corrosion resistance of corundum castables have been investigated in this paper. When 2% nano silica was added, the pore diameters of castables could be decreased to 15 nm (at 110 °C), 1 μm (1100 °C) and 6 μm (1500 °C), respectively. The corresponding reducing magnitude of pore size is 98.5%, 83.3% and 33.3%. The HMOR of castables fired at 1500 °C increased by 110% to 3.64 MPa. Furthermore, after three thermal shock cycles, the residual strength ratio of castables increased from 5.2% to 15.3%. A large amount of cross-distributed columnar mullite was formed between nano silica and α-Al 2 O 3 by the two-dimensional nucleation mechanism, which remarkably enhanced the high temperature properties. The penetration index reduced from 30.86% to 19.88%, suggesting that smaller pore size and higher viscosity had a great influence to the penetration process.
研究领域:
材料科学
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陶瓷
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耐火材料
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高温性能
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2021
·Vol. 47
·期 18
·26310-26318
·
IF 4.527
Hao Liu,Chuang Jie,Zhongzhuang Zhang,Zhoufu Wang,Yan Ma,Xitang Wang,Honghong Wang,Ke Wu,Guoqiang Zheng
A study of magnesia refractories containing glucose, citric acid, and metallic Al and their influences on structure, mechanical strength , and thermal shock resistance , is presented. Combined with thermodynamic calculation, microstructure, and properties analysis, the results show that formation of gluconates and citrates from the introduced glucose and citric acid enhanced the bonding of raw materials and the curing strength of samples. The pyrolysis of gluconates and citrates, and the oxidation and nitridation of metallic Al had significant effects on the microstructural evolution of magnesia refractories after high temperature treatments, mainly AlN and MgAl 2 O 4 whiskers in pores and particle gaps. The formation and development of whiskers give rise to samples improved toughness and thermal shock resistance. Increasing the metallic Al content from 0 wt% to 2 wt% enhanced the fracture surface energy of samples heat treated at 1400 °C from 82.22 kJ/m 2 to 119.75 kJ/m 2 . Meanwhile, after three thermal-shock cycles, the residual strength ratios of heat treated samples were elevated from 52.8% to 67.9%. On the basis of influences of phase transformation on the structure and properties of samples at different temperatures, considering the structural compactness and ability to withstand external stress for magnesia refractories used in metallurgical field, it is suggested that when glucose and citric acid are used as binders, the addition of metallic Al should be less than 3 wt%.
研究领域:
材料科学
·
陶瓷
·
耐火材料
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热力学
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微观结构分析
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2020
·Vol. 46
·期 15
·24238-24247
·
IF 3.83
Hao Liu,Chuang Jie,Zhoufu Wang,Zhongzhuang Zhang,Xitang Wang,Yan Ma
The present study aims to clarify the influence of BaSO 4 on composition, microstructural evolution and properties of magnesia refractory castables. Castables with different BaSO 4 contents were prepared using calcined magnesia, microsilica , and BaSO 4 as raw materials. The results show that introducing BaSO 4 can significantly enhance slag resistance of magnesia refractory castables. Castables presented high compactness and mechanical properties with 0–3 wt% BaSO 4 for the liquid sintering process and formation of BaMgSiO 4 at high temperature. Then compactness of castables decreased when BaSO 4 content increased from 5 wt% to 10 wt% for its decomposition and a subsequent increase in the pore content. BaSO 4 presented minor effects on the low temperature (1100 °C) structure of castables and played an important role in enhancing high temperature slag resistance, owing to its high structural stability till 1550 °C. The slag resistance mechanism of castables with BaSO 4 is that Al 3+ in slag was incorporated into periclase intergranular to form BaAl 2 O 4 phases during corrosion process, resulting in the increased slag viscosity and suppressed continuing penetration. The research of this work provides a new insight into microstructure and properties enhancement of magnesia refractory castables used in metallurgical field.
研究领域:
材料科学
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耐火材料
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陶瓷
·
高温工程
·
冶金
✓ 已验证
DOI
高影响因子
Minerals
·
2018
·Vol. 8
·期 4
·125
·
IF 1.835
Zhuang Li,Yijun Cao,Yuanli Jiang,Guihong Han,Guixia Fan,Luping Chang
In order to explore the commercialized applications of the low-grade bauxite in the refractory industry, a calcination integrated with acid leaching method was adopted to remove the potassium (K) and iron (Fe) from the diaspore-illite (DI) type low-grade bauxite. Following calcining the bauxite at different temperatures, the leaching parameters, including the sulfuric acid concentration, temperature, sulfuric acid to bauxite ratio, and reaction time were systematically studied. The appropriate and economical conditions for removing the impurities were found to be calcining the bauxite at 550 °C, and leaching it with a sulfuric acid solution of 1.2 mol/L, sulfuric acid/bauxite ratio of 9 mL/g at a reaction temperature of 70 °C and reaction time of 2 h, under these conditions, the removal efficiency of K and Fe from the bauxite can reach 30.32% and 47.33%, respectively. The treated bauxite was examined by XRD analysis, SEM observations, and chemical analysis. Kinetics of the removing process were calculated by two models, and the results showed that the leaching process was controlled by the mixed shrinking core model, which was affected by both the diffusion through solid layer and the interface transfer. In summary, the approach in this work presents a promising process for comprehensive utilization of the low-grade bauxite.
研究领域:
矿物加工
·
湿法冶金
·
材料科学
·
耐火材料
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2020
·
IF 3.83
Chuang Jie,Hao Liu,Zhoufu Wang,Xitang Wang,Yan Ma
To improve the energy-saving capacity of magnesia refractory castables for working lining of high-temperature kilns, this study presents the researches on microstructure and properties of lightweight magnesia refractory castables with porous matrix fabricated by direct foaming method. The results show that formation of closed-pores in the matrix significantly enhanced high-temperature thermal insulation performance of castables with minor changes of slag corrosion resistance . The thermal conductivity of the lightweight magnesia castables at 1000 °C was below 1.2 W/m·K, which is 47.8% lower than that of the referenced magnesia castable. The increasing content of SDS (foaming agent, over 0.02 wt%) led to increments of size and number of large-sized pores, resulting in the significantly decreased density and mechanical performances. The slag resistance mechanism reveals that, in addition to intergranular penetration, the accumulation of slag and penetration between adjacent pores were the major ways of slag mass transfer in lightweight magnesia castables. In conclusion, controlling the size (below 53.2 μm), number and distribution of closed-pores in the matrix is effective to realize the coupling of high thermal insulation, mechanical properties and slag resistance for lightweight magnesia castables used in the metallurgical field.
研究领域:
材料科学
·
耐火材料
·
无机非金属材料
·
高温工程材料
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）