RENEWABLE ENERGY
·
2020
·
IF 6.274
Yujiao Zhang,Shengli Niu,Kuihua Han,Yingjie Li,Chunmei Lu
Calcium oxide is one of the most promising heterogeneous catalysts for biodiesel production . However, an inherent drawback of CaO is the leaching of active species into the reaction solution with the degraded reusability . To strengthen the stability, different supports are composited with the SrO–CaO oxide through the hydrothermal method and mass ratio of SrO to CaO are optimized to get the best outcome of the catalyst. Meanwhile, various characterization methods, including TG , XRD , SEM-EDX, CO 2 -TPD, XPS , ATR-FTIR and ICP-AES, are used to explore the physicochemical properties of catalysts. The 0.4-SrO-CaO-Al 2 O 3 catalyst shows the best catalytic capability in transesterification of palm oil with methanol to produce biodiesel , where the FAME yield of 98.16% is achieved with the molar ratio of methanol to oil of 18:1 and catalyst concentration of 7.5 wt% at 65 °C for 3 h. Besides, ascribed to the greatly reduced leaching out of the active species , this catalyst presents the satisfying reusability and the FAME yield is slightly decreased to 92.61% for the fifth reused cycle. Therefore, this modification method for SrO–CaO–Al 2 O 3 is feasible for enhancing the catalytic stability in transesterification .
研究领域:
催化化学
·
可再生能源
✓ 已验证
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2023
·
IF 5.7
Haonan Cui,Hongcheng Yang,Hua Wang,Yixuan Zheng,Yuchen Wang,Hongyu Yang,Enzhu Li
CaO-Al 2 O 3 -B 2 O 3 (CAB) glass-ceramics with varying Al 2 O 3 content were fabricated using the melting method including melting and quenching of mixture of raw materials. The obtained glass powder was pressed into the desired shape and sintered for measurement. At 900 °C, the crystallinity initially increased and then decreased with increasing Al 2 O 3 content. The highest crystallinity of 62.29 % was obtained when the Al 2 O 3 content was 0.5 mol%, and exhibited excellent dielectric properties : ε r = 4.35, Q × f = 53,085 GHz, and τ f = –33.95 ppm/°C. The variation of dielectric properties with increasing Al 2 O 3 content is attributed to the crystallinity process. The crystallization process of CAB system was determined by crystallization activation energy , the lowest value of 302.085 kJ/mol corresponds to the highest crystallinity. The crystallization, dielectric properties and sintering behavior of CAB system indicate that CAB system prepared by melting method have promising prospect as new LTCC glass-ceramics.
研究领域:
材料科学
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电子工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2023
·
IF 5.7
Sheng-Jin He,Ling-Feng Su,Chuang-Tian Zhan,Xiu-Bin Chen,Wei-Ming Guo,Shi-Kuan Sun,Li-Xiang Wu,Jia-Xiang Xue,Hua-Tay Lin
Low-temperature joining of SiC ceramics using raw CaO-Al 2 O 3 -MgO-SiO 2 mixed powders (CAMS-P) and CaO-Al 2 O 3 -MgO-SiO 2 glass (CAMS-G) as additives for the liquid-phase sintering of SiC nanopowders (NITE phase) in combination with surface oxidation was studied. Using CAMS-P as an additive for SiC joining required 1650 °C and produced a lower shear strength of 77.2 ± 3.5 MPa, compared to untreated SiC (108.2 ± 15.8 MPa). Using CAMS-G as an additive, the compactness of SiC joints obtained at 1550 °C was higher than that of NITE joints obtained at 1650 °C with CAMS-P as an additive. Nonetheless, the low joining temperature resulted in gaps and delaminations at the interface, and the joints strength was only 48.3 ± 5.6 MPa. Incorporating CAMS-G as an additive and surface oxidation achieved reliable NITE phase joining at 1550 °C, with no observed gaps or delaminations at the interface. The resulting joints strength was as high as 100.0 ± 0.8 MPa. The joining mechanism was discussed and compared, involving microstructural analysis .
研究领域:
材料科学
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陶瓷工程
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产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2024
·Vol. 35
·期 1
·1-14
·
IF 2.8
Zhang Yajuan,Lu Yang,Shan Yiting,Wang Jie,Feng Jingmin,Zhou Hongqing
Herein, (1 − x )CaO–Al 2 O 3 –B 2 O 3 –SiO 2 (CABS)/ x Ba(Mg 1/3 Nb 2/3 )O 3 (BMN; x = 0.4, 0.45, 0.5, 0.55, and 0.6) composites were prepared, and the impact of the BMN and low-softening-point glass content in CABS/BMN composites on the sintering, dielectric, thermal, and mechanical properties of the prepared composites was investigated. The main crystal phases of the CABS/BMN composites are BMN and Ba 2 NaNb 5 O 15 (BNN). The crystallization temperature of the composite was reduced by an appropriate amount of BMN. BMN ceramics (40–60 wt%) was added to the CABS glass, and the composites were sintered at 800 °C, 825 °C, 850 °C, 875 °C, and 900 °C. To elucidate the influence mechanism of different glass contents and sintering temperatures on the properties of the composites, different qualitative and quantitative instruments were used to study the composite properties. The CABS/BMN composite containing 50 wt% CABS glass sintered at 875 °C exhibits the following ideal properties: volumetric density of 3.57 g/cm 3 , dielectric constant of 17.97, dielectric loss of 6 × 10 −4 , \(Q \times f\) value of 10,947 at 9.5 GHz, bending strength of 157.7 MPa, and coefficient of thermal expansion of 5.9 ppm/K. Microstructure analysis reveals that the microstructure of the composite is dense, the pores are few, the surface morphology is uniform and flat, and the composite does not react with silver electrodes, making it suitable for applications utilizing medium dielectric constant low-temperature co-fired ceramic materials at low sintering temperatures.
研究领域:
材料科学
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电子工程
✓ 已验证
DOI
高影响因子
CATALYSIS LETTERS
·
2014
·Vol. 144
·期 7
·1188-1196
·
IF 2.291
Zhu Lihua,Cao Maohong,Zhou Hua,Zhang Nuowei,Zheng Jinbao,Li Yunhua,Chen Bing H.
Abstract
A series of CaO/Al 2 O 3 base catalysts with different crystal phases is prepared via thermal treatment. The as-prepared base catalysts are tested through Baeyer–Villiger oxidation of cyclohexanone to ε-caprolactone in liquid-phase using a mixture of aqueous hydrogen peroxide and benzonitrile as oxidant. The corresponding results show that the CaO/Al 2 O 3 catalysts with high thermal treatment temperature (e.g. 900 °C) exhibit excellent activity as well as stability. Upon these, the catalysts are characterized by TG–DTG, XRD, N 2 -physisorption, SEM and CO 2 -TPD techniques. The characterization results clearly suggest that such a stable and efficient catalytic performance is beneficial from the formation of calcium aluminate phase, thus overcoming one of base catalyst application barriers, that Ca or CaO species loss (leach) from CaO-based catalysts during reactions. Correspondingly, it can be inferred that the treatment of the catalysts at different temperatures results in the diverse distribution of basic strength. Furthermore, it is also demonstrated that the suitable base strength (medium strength is good for the reaction selected in the work) plays a critically role in the improvement of catalytic performance. Finally, the effects of operation conditions on catalytic activity and product selectivity are also determined and discussed. Graphical Abstract
研究领域:
催化化学
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材料科学
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产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Sheng-Jin He,Jia-Pei Chen,Wei-Ming Guo,Xiu-Bing Chen,Huan Zhou,Chuang-Tian Zhan,Shi-Kuan Sun,Yun Li,Li-Xiang Wu,Jia-Xiang Xue,Hua-Tay Lin
In this study, CaO–Al 2 O 3 –MgO–SiO 2 glass was utilized to join SiC after surface polishing and etching, without the application of pressure. To join polished SiC at 1250 °C using CaO–Al 2 O 3 –MgO–SiO 2 glass proved unsuccessful. However, when polished SiC was joined at 1350 °C, the joint shear strength was 108.0 ± 15.5 MPa. Etching polished SiC with a NaOH–K 3 [Fe(CN) 6 ] solution effectively removed surface carbon, resulting in numerous micro-pits, that increased the joining area and improved the wettability of CaO–Al 2 O 3 –MgO–SiO 2 glass. The joint strengths of etched SiC joined at 1250 °C and 1350 °C were 29.0 ± 11.6 MPa and 125.1 ± 19.6 MPa, respectively. After ablation at 1200 °C for 10 min, the retained strength of the etched joints (joined at 1350 °C) was 61.9 ± 4.0 MPa, whereas the strength of the polished joints decreased to only 36.6 ± 10.7 MPa. Surface etching demonstrates the potential to significantly enhance the strength and high-temperature resistance of SiC joints.
研究领域:
材料科学
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陶瓷工程
·
表面工程
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry A
·
2018
·Vol. 6
·期 8
·3462-3470
·
IF 9.931
Rui Han,Jihui Gao,Siyu Wei,Yanlin Su,Yukun Qin
High-temperature sorption of CO2via calcium looping is a promising technology for the implementation of carbon capture and storage (CCS). However, the major drawback of this technology is the rapid deactivation of CaO sorbents due to sintering. Here, a facile and cost-effective limited-space metal organic chemical vapor deposition approach is proposed to develop CaO-based sorbents exhibiting a very high and cyclically stable CO2 uptake. The TEM results show that Al2O3 nanoparticles (4–8 nm) are uniformly coated onto CaO crystalline grains, thus effectively inhibiting the sintering of sorbents. After 20 severe cycles, the synthetic sorbent, stabilized by 10 mol% Al2O3, exceeded the CO2 uptake of the benchmark CaO by more than 300%. Furthermore, the influence of Ca-based precursors on the synthetic sorbent's cyclic CO2 uptake was established. The result shows that the sorbents synthesized from different Ca-based precursors all demonstrate high cycling stability, which means that low-cost and high-performance sorbents can be synthesized through selecting a low-cost Ca precursor, such as CaCO3.
研究领域:
化学工程
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材料科学
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2017
·Vol. 43
·期 16
·13810-13816
·
IF 2.986
Qingong Zhu,Huanping Wang,Ying Tian,Ren Gao,Shilong Zhao,Lihui Huang,Shiqing Xu,Xianghua Zhang
Glass system with compositions of 93.9% ( x CaO- y Al 2 O 3 - z SiO 2 )−5% MgO-1% B 2 O 3 −0.1% Fe 2 O 3 has been prepared by a conventional melt-quenching technique, and the glass forming region and the mechanical properties of the derived glasses were investigated. The approximate glass forming region was found to be x = 10～35%, y = 10～35% and z = 50～80%, while the rest of the area was crystallization zone or crack zone. As x = 10%, y = 25% and z = 65% (Sample 13), the investigated glass possesses the optimum volume density, bending strength , compression strength and modulus, which are 2.572 g/cm 3 , 74.05 MPa, 312.84 MPa and 163.96 GPa, respectively. Compared to sample 13, samples with different compositions have reduced the volume density, lowered the Raman intensity and improved the optical band gap. For the mechanical properties, with decreasing the contents of SiO 2 , the bending strength firstly increases, then decreases and finally shows a relatively small increasing trend. The dependence of compression strength and compression modulus on SiO 2 content shows a similar trend to the bending strength. Moreover, the optical band gap and Raman spectrum of the sample 13 indicate that the number of oxygen bonds in the bridge reach the maximum, which could further confirm a significantly improvement on the mechanical properties.
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DOI
高影响因子
JOURNAL OF NON-CRYSTALLINE SOLIDS
·
2026
·
IF 3.6
Zhitao Shan,Hong Wang,Shujiang Liu,Yanfei Zhang,Cheng Zuo,Qiuju Zheng,Haizheng Tao,Yuanzheng Yue
In this work, we investigated the structural and physical property evolutions induced by the substitution of Al 2 O 3 by Ga 2 O 3 in two series of CaO-Al 2 O 3 -Ga 2 O 3 (CAG) glasses. To suppress crystallization, glasses with compositions of (I) 50CaO• (50- x )Al 2 O 3 • x Ga 2 O 3 ( x = 0–50 mol%) and (II) 63CaO• (37- x )Al 2 O 3 • x Ga 2 O 3 ( x = 0–37 mol%) were prepared via containerless aerodynamic levitation technique. It was found that with increasing substitution of Al 2 O 3 by Ga 2 O 3 (i.e., increasing x ), both glass series exhibited monotonic decreases in hardness, glass transition temperature and thermal expansion coefficient. High-resolution XPS analyses revealed that the two glass series exhibited distinct compositional dependences in their local structural evolution. Specifically, in series I ([CaO]:[Al 2 O 3 +Ga 2 O 3 ] = 1:1), the coordination environments of O, Ga, and Al remained largely unchanged upon substitution. In contrast, Series II ([CaO]:[Al 2 O 3 +Ga 2 O 3 ] = 12:7) exhibited significant shifts in O and Al coordination, while the Ga environment was only minimally affected. Furthermore, XPS indicated that trace OH - species preferentially interact with Al/Ga-O bonds by non-bridging oxygens within [AlO 4 ] or [GaO 4 ] tetrahedra. These findings elucidate the critical roles of both [CaO]/[Al 2 O 3 +Ga 2 O 3 ] and [Al 2 O 3 ]/[Al 2 O 3 +Ga 2 O 3 ] ratios in tailoring the structure - property relationships of CAG glasses.
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产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Chuang-Tian Zhan,Jin-Yuan Wu,Kun-Heng Huang,Yun Li,Li-Xiang Wu,Sheng-Jin He,Yang-Qing Liu,Ze-Xi Zhang,Wei-Ming Guo,Jia-Xiang Xue,Hua-Tay Lin
The pressureless-sintered silicon carbide ceramic with and without surface texturing was joined with CaO-Al 2 O 3 -MgO-TiO 2 -SiO 2 glass filler. The experimental results showed that without texturing applied to SiC substrates, the shear strength of SiC joints was 40.8 ± 6.3 MPa, with failure occurring at the interlayer. Unfilled regions in the interlayer limited the shear strength of the joints. When texturing was applied to SiC substrates, SiO 2 layer was formed on the surface of substrates due to high-temperature oxidation, which subsequently promoted the wettability of filler on substrates. The textured grooves on SiC substrates could be filled with glass material during joining process. The shear strength of textured SiC joints was 69.3 ± 9.9 MPa with a mixed-mode failure when the direction of shear load was perpendicular to the texturing direction. The better wettability, larger joining area, and interlocking structure between the glass filler and substrates enhanced the shear strength of textured joints.
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2025
·
IF 5.6
Kun-Heng Huang,Chuang-Tian Zhan,Huan Zhou,Shi-Kuan Sun,Yun Li,Li-Xiang Wu,Jia-Xiang Xue,Jian-Han Zhai,Wei-Ming Guo,Hua-Tay Lin
This study investigated the effect of laser texturing parameters on the shear strength and microstructure of SiC ceramic joints, which were joined using CaO-Al 2 O 3 -MgO-Y 2 O 3 -SiO 2 (CAMYS) glass filler. It was demonstrated that laser texturing promotes the formation of SiO 2 on the surface and subsequent filler adhesion. Groove depth and spacing were identified as critical factors for joint performance. Excessive groove depth (∼60 μm) caused incomplete groove filling and reduced joint strength, due to void formation. Similarly, decreased texturing spacing (∼200 μm) induced excessive thermal damage and compromised joint robustness, as observed in laser-treated ceramic surfaces. Among the five evaluated texturing configurations, the optimal condition, defined by a groove depth of ∼30 μm and spacing of ∼500 μm, yielded a maximum shear strength of 80 ± 12 MPa, representing a 77.8 % improvement over untextured joints (45 ± 10 MPa).
研究领域:
材料科学
·
陶瓷连接技术
·
表面工程
·
无机非金属材料
·
焊接与连接
✓ 已验证
产品关联
DOI
高影响因子
Sustainability
·
2024
·Vol. 16
·期 2
·890
·
IF 3.3
Miao Tian,Qiongqiong Wang,Songsong Wang,Xingbang Wan,Qinmeng Wang,Xueyi Guo
Waste electrical and electronic equipment (WEEE) contains various valuable metals, making it a potential secondary resource for sustainable metal usage. Pyrometallurgical smelting is an efficient technique to recycle WEEE by extracting precious metals into copper matte and removing impurities into slags. The impact of WEEE impurities such as CaO and Al2O3on the phase compositions of the smelting products attracts great attention for industrial metal recovery. This study clarified the impact of CaO and Al2O3on the equilibrium phase compositions of copper matte and SiO2-saturated FeOx-SiO2-Al2O3-CaO slags. The high-temperature smelting experiments were taken at a controlled p(SO2) of 0.1 atm and 1300 °C, followed by quenching and electron probe microanalysis. The results showed that the copper and sulfur in the smelting system were highly deported into copper matte, and their distribution in matte was enhanced by increasing CaO and Al2O3concentrations introduced by WEEE. The chemical copper dissolution in slags increased with increasing matte grade but decreased by adding CaO and Al2O3. The iron was preferentially concentrated in slags, and higher matte grades improved the iron distribution in slags. The current experimental results enrich fundamental thermodynamic data and help optimize WEEE smelting operations for efficient recovery of valuable metals.
研究领域:
冶金学
·
环境工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）