Journal of Building Engineering
·
2023
·
IF 6.4
Ting Zhang,Hongbo Tan,Jian Ni,Baoguo Ma,Xiaohai Liu,Pian Chen,Tao Shi
To lower the corrosion hazards of the steel bar in reinforced concrete, binding chloride ion by producing Cl-AFm is an effective way. In the presence of calcium ions and sulfate ions, Cl-AFm could transform into ettringite , and release the chloride ions into pore solution , with negative effect on reinforced concrete. In order to avoid the negative effect, barium ion was introduced to preferentially precipitate the sulfate ions. In this study, the effect of barium ion on the transformation reaction of ettringite into Cl-AFm was studied, and the combination effect of barium ion and sulfate ion on chloride binding was discussed. The results showed that barium ion could improve the chloride binding capacity of ettringite. The mechanism was that barium ion could be precipitated by sulfate from AFt to form BaSO 4 , and then result in the formation of Cl-AFm.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2025
·
IF 5.6
Jianfeng Wu,Xinxin Shi,Shaoheng Liu,Xiaohong Xu,Yaqiang Shen,Deng Zhang
The absorptivity of endothermic materials serves as a critical index for solar thermal power photothermal conversion systems, and ceramic-based endothermic materials characterized by high absorptivity also exhibit elevated sintering temperatures. In this study, CaF 2 was employed as an additive to investigate its effects on the physical properties and microstructure of the samples, with a particular focus on the mechanism by which CaF 2 reduces the sintering temperature of corundum-based endothermic ceramics. The results showed that the G2 sample (1 wt% CaF 2 ), sintered at 1650 °C, displayed the best physical properties, including 93 % absorptivity, 165.43 MPa bending strength. The sintering temperature of the CaF 2 -doped G-series samples was around 60 °C lower due to liquid-phase calcium hexaaluminate formation from CaF 2 and Al 2 O 3 , which enhanced atomic migration and facilitated ceramic matrix sintering. Additionally, the capillary forces of the liquid-phase calcium hexaaluminate promoted ceramic matrix shrinkage and accelerated corundum-based grain growth through the dissolution-precipitation mechanism, leading to densification. Moreover, the G2 sample exhibited excellent durability, with absorptivity decreasing by only 1.9 % after 100 h at 1000 °C.
研究领域:
材料科学
·
太阳能技术
✓ 已验证
产品关联
DOI
高影响因子
CONSTRUCTION AND BUILDING MATERIALS
·
2024
·
IF 7.4
Yuyang Zhao,Zhaoyang Sun,Gang Qiao,Xu Fang,Binmeng Chen
Given that CO 2 chamber and high inner pressure are needed in the traditional carbonation curing, we propose an in-situ internal carbonation by mesoporous silica nanoparticles (MSN) to tackle the challenge, leveraging its high specific surface area. In this study, MSN was functionalized with γ-aminopropyl triethoxy silane (MSN-amine), followed by reacting with CO 2 (CO 2 carrier) and mixing with alite paste. Phase transformation and nucleation behavior were investigated by conducting comparative in-situ carbonation of alite paste, utilizing MSN-amine in two configurations: one adsorbing CO 2 (MSN-amine-AC) and the other desorbing CO 2 (MSN-amine-DC). Results indicated that semi-crystalline C-S-H is produced in alite paste containing MSN-amine-DC (Ap-MSN-DC) through pozzolanic reaction while amorphous calcium carbonate (ACC) is generated in alite paste with MSN-amine-AC (Ap-MSN-AC) via in-situ carbonation, both of which promote the early reaction of alite. Additionally, low Ca/Si ratio calcium silicate hydrate (C-S-H) with negative electric potential developed as MSN-amine-DC gradually eroded, collapsed, and chemically transformed into reactive sites. Conversely, the ACC generated in MSN-amine-AC blocks the mesopores, inhibits the pozzolanic reaction and preserves the silica skeleton. Subsequently, calcite is crystallized via the dissolved ACC and embedded itself on the surface of C-S-H with positive electric potential, turning to nucleation sites physically. To conclude, the proposed in-situ internal carbonation models for MSN-amine-modified alite paste offer insights into microstructural evolution.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Yichong Li,Huizhong Zhao,Han Zhang,Jun Yu,Wei Wang,Jiulin Xu
Ferrotitanium slag (FTS) is the waste product that has gained attention as a potential calcium hexaaluminate (CA 6 ) resource in recent years. In this study, the phase distribution of FTS and CA 6 aggregate was compared, and its effect on the cryolite resistance of castables was further studied. Scanning electron microscopy and least-squares refinement program were used to characterize the phase distribution and crystallographic parameters of ferrotitanium slag. Computational and experimental results demonstrate that ferrotitanium slag contains denser and larger hibonite crystals compared to synthetic calcium hexaaluminate. Ti element exists in the hibonite crystal in the form of coupled substitution or direct substitution of Al 3+ . Performance evaluation in refractory castables also confirms the resulting improvement in corrosion resistance.
研究领域:
材料科学
·
冶金工程
✓ 已验证
产品关联
DOI
高影响因子
CONSTRUCTION AND BUILDING MATERIALS
·
2023
·
IF 7.4
Chen Liang,Piqi Zhao,Haohang Zou,Qinghao Song,Pengkun Hou,Yongbo Huang,Shoude Wang,Lingchao Lu
Polymer-modified cement-based coatings are widely used in the field of concrete protection. However, in harsh environments such as the ocean, the core durability indicators such as anti-UV aging resistance and anti-chloride corrosion of the coating need to be further improved. In this study, the polypropylene (PP) fiber was introduced into the composite coating with silicone-modified polyacrylate (SPA) emulsion and calcium sulphoaluminate (CSA) cement as the main body. And the influences of PP fiber on the mechanical properties, UV aging resistance and chloride penetration were mainly discussed. Results showed that PP fiber not only significantly improved the tensile strength of the coating as expected (increment > 60%), but also showed the obviously positive effect on the bonding strength and wear resistance. For UV aging conditions, PP fiber could reduce the loss rate of elongation at break of the coating. For chloride corrosion, the chloride penetration resistance of the coating was also significantly improved by 48.92%. The enhancement was attributed to PP fiber itself and its effects on the coating, resisting the external stress, promoting the break of bubbles and reducing microporosity. In addition, the application was also attached to this study to verify the performance of the coating.
研究领域:
土木工程
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
DALTON TRANSACTIONS
·
2018
·Vol. 47
·期 11
·3819-3830
·
IF 4.099
Karim Khan,Ayesha Khan Tareen,Sayed Elshahat,Ashish Yadav,Usman Khan,Minghui Yang,Luigi Bibbò,Zhengbiao Ouyang
One of the greatest challenges in the enhancement of the electrical properties of conductive mayenite [Ca24Al28O64]4+(4e−) (hereinafter C12A7:e−) is the design of a more suitable/simple synthesis strategy that can be employed to obtain the required properties such as excellent stable electrical conductivity, a high electron concentration, outstanding mobility, and an exceptionally large surface area. Therefore, to synthesize C12A7:e− in the metallic state, we proposed a facile, direct synthesis strategy based on an optimized sol–gel combustion method under a nitrogen gas environment using the low-cost precursors Ca(NO3)2·4H2O and Al(NO3)3·9H2O. Using this developed strategy, we successfully synthesized moderately conductive nanoscale C12A7:e− powder, but with unexpected carbon components (reduced graphene oxide (rGO) and/or graphene oxide (GO)). The synthesized C12A7:e− composite at room temperature has an electrical conductivity of about 21 S cm−1, a high electron concentration of approximately 1.5 × 1021 cm−3, and a maximum specific surface area of 265 m2 g−1. Probably, the synthesized rGO was coated on nanocage C12A7:e− particles. In general, the C12A7:e− electride is sensitive to the environment (especially to oxygen and moisture) and protected by an rGO coating on C12A7:e− particles, which also enhances the mobility and keeps the conductivity of C12A7:e− electride stable over a long period. Doped mayenite electride exhibits a conductivity that is strongly dependent on the substitution level. The conductivity of gallium-doped mayenite electride increases with the doping level and has a maximum value of 270 S cm−1, which for the first time has been reported for the stable C12A7:e− electride. In the case of Si-substituted calcium aluminate, the conductivity has a maximum value of 222 S cm−1 at room temperature.
研究领域:
无机化学
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材料科学
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纳米材料
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固态化学
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电化学
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功能材料
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）