Coatings
·
2023
·Vol. 13
·期 7
·1266
·
IF 3.4
Qian Kou,Weiliang Jin,Chuntao Ge,Jie Pang,Jun Zhang,Geir Martin Haarberg,Saijun Xiao,Ping Wang
In this paper, electrodeposition of a molybdenum coating was conducted in Na3AlF6-NaF-Al2O3-MoO3molten salts at 930 °C to investigate the availability of preparation of thick molybdenum coatings. The effects of current density and electrodeposition time on the morphology of the produced molybdenum coating were studied. With the increase of current density (10~70 mA·cm−2), the coating thickness was increased from 10 μm to 30 μm, with all the current efficiency above 97%. Under a current density of 30 mA/cm2, with the rise of electrodeposition time (10~60 min), three stages of the deposit growth were observed, including the formation of a large number of fine crystals, transformation into fibrous morphology and well-developed faceted grains. The formation of a large number of fine crystals at the initial stage of the electrodeposition could facilitate electroplating molybdenum coatings with good quality at higher current density and longer duration. Thus electrodeposition at a current density of 100 mA·cm−2for 3 h has been performed, resulting in the preparation of relatively flat, dense, and coherent molybdenum coatings with a thickness of 140 μm on a nickel substrate, with a current efficiency above 85%. It is anticipated that the electrodeposition of molybdenum coatings in the present molten system is suitable for electroplating thick molybdenum coatings.Keywords:cryolite-based molten salt;electrodeposition;molybdenum coating;nickel substrate
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高影响因子
Catalysis Science & Technology
·
2023
·Vol. 14
·期 2
·334-342
·
IF 5
Zhou Yang,Ru Wang,Hongji Liu,Zhou Chen,Xiaoli Hu,Limin Sun,Weikun Lai,Yunyun Dong,Weiping Fang,Xiaodong Yi
Selective hydrogenation is a significantly important catalytic process in many industrial processes, where Pd-based catalysts are the most commonly used. Herein, the surface properties of γ-Al2O3 were modified by the layered flower-like architectures of alkaline MgO using a simple hydrothermal method. Then, a series of Pd/Al2O3–MgO catalysts were prepared by an incipient wetness impregnation method for the selective hydrogenation of isoprene. The results showed that the Pd/Al2O3–0.12MgO catalyst exhibited superior catalytic performance with a high activity (93%) and high selectivity (99%) for the semi-hydrogenation products. Systematic studies have demonstrated that the support effect plays an important role in dispersing and stabilizing palladium particles. The reasons for the improved catalytic performance were attributed to the high dispersion of Pd nanoparticles, the changed electronic structure of Pd, and the strong interaction between Pd nanoparticles and supports. This work opens a simple route to regulate the electronic properties of active metal sites via support modification for selective hydrogenation reactions.
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Materials Today Communications
·
2023
·
IF 3.8
Lindai Sun,Zexing Liu,Hui Huang,Yang Xia,Yongping Gan,Xinping He,Wenkui Zhang,Jun Zhang
Radiative cooling utilizes high solar reflectivity and high infrared emissivity to achieve temperature cooling down, which has attracted extensive research interest as a zero-energy consumption manner. However, the design of photonic structures and metamaterials for radiative cooling do not exploit commercialization prospects due to high production costs and structural complexity. Here we propose an economical and scalable electrospinning method for fabricating high-performance sun-shading and radiative cooling composite flexible film. The composite film is a non-woven fabric of nanofibers with polymethyl methacrylate (PMMA) and aluminum oxide (Al 2 O 3 ) nanoparticles . The diameter of the nanofibers distributes in the range of 300–1200 nm and Al 2 O 3 nanoparticles are wrapped in the nanofibers. The nanofibers strongly scatter sunlight to enable high solar reflectivity and back-reflection layer is no more necessary. Molecular vibrations of PMMA and phonon polarization resonance of Al 2 O 3 nanoparticles synergistically result in high infrared emissivity. At a thickness of 0.30 mm and with an Al 2 O 3 content of 8%, this material exhibits exceptional solar reflectance levels of approximately 95% between wavelengths of 1.1–2.5 µm. Additionally, it demonstrates an extremely low rate of solar absorption of approximately 5.5% between wavelengths of 0.3–1.1 µm, distinguishing itself as a highly effective solar selective surface even without the inclusion of a back-reflective layer. Furthermore, the material exhibits ultrahigh infrared emissivity levels of approximately 0.98 within atmospheric windows ranging from 8 to 13 µm. These remarkable characteristics position this material as a highly promising candidate for use in solar thermal energy conversion systems. As a result, the device shows a cooling performance that reaches a temperature decrease of up to 4.3 °C under 1000 W/m 2 peak solar intensity and a decrease of 5.9 °C during nighttime. The composite film has enormous potential for use in vehicle shading and personal thermal management. Moreover, its mechanical properties allow for the flexibility needed to meet the demands of everyday use. Our work provides a straightforward and scalable method to manufacture products with exceptional sun shading and radiative cooling capabilities.
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International Journal of Applied Ceramic Technology
·
2023
·Vol. 21
·期 1
·427-437
·
IF 2.1
Yulong Wang,Zhoufu Wang,Xitang Wang,Hao Liu,Yan Ma,Pengcheng Jiang,Yunjie Dong,Jiwei Niu
Short carbon fiber is a promising candidate for reinforcing carbon-containing refractories at the macro scale due to its excellent high-temperature stability and mechanical properties. In this work, the microstructure evolution of short carbon fiber and the effect of its addition on the properties of Al 2 O 3 –C refractories are investigated. The results show that adding short carbon fiber could affect the distribution of in situ ceramic phases, combined with the cross-scale reinforcement effect, leading to high strength—the CMOR of short carbon fiber containing refractories could be 23.0% higher than the free ones, while the HMOR could be 22.0% higher. Furthermore, the results suggest that the short carbon fiber containing refractories treated at 1400°C possesses high resistance to the initiation of crack propagation, which could be attributed to the high bonding strength brought by carbon fiber. Noteworthy, adding short carbon fiber could improve thermal shock resistance. The short carbon fiber containing refractories treated at 1300°C could possess a higher residual strength ratio than free ones. For instance, the specimen containing 0.1 wt% short carbon fiber shows the highest residual strength ratio (87.7%).
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CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Jie Fu,Ying Zhang,Zhibiao Ma,Linghan Bai,Ruyu Fan,Wenlong Xu,Mathieu Allix,Cécile Genevois,Emmanuel Veron,Yafeng Yang,Hui Wang,Jianqiang Li
Transparent Lu 3 Al 5 O 12 (LuAG) ceramics have become very promising phosphor matrix materials due to their high doping concentration and luminous efficiency, thermal conductivity and thermal stability. However, LuAG transparent ceramics prepared by traditional powder sintering method are facing several problems, such as time-consuming and energy-consuming, complex preparation process, high quality of raw material powders and large crystalline grain size. Here we report facile elaboration of transparent LuAG-Al 2 O 3 two-phase nanocrystalline ceramics through pressureless crystallization (1000 °C, 2 h) of 72 mol.% Al 2 O 3 -28 mol.% Lu 2 O 3 (ALu28) bulk glasses combined with the crystallization kinetics analysis. The results of the crystallization kinetics analysis show that the ALu28 bulk glasses have a low activation energy (<750 kJ mol −1 ) and a crystallization mechanism of three-dimensional crystal growth mode accompanied by volume nucleation. The resulting LuAG-Al 2 O 3 ceramics with nanosized grains and dense three-dimensional network nanostructures present good transmittance (80.6 %@780 nm) and excellent mechanical properties (hardness is 24 GPa).
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International Journal of Applied Ceramic Technology
·
2023
·
IF 2.1
Mengwen Zhang,Na Cao,Fanyu Meng,Lutong Yang,Binyang Jiang,Jinsheng Li,Lei Fan,Shoulei Yang
High-toughness Al 2 O 3 –Ti(C,N) composites reinforced by cBN particles were prepared by the new oscillating pressure sintering technique. The density, phase, and microstructure evolution of the Al 2 O 3 –Ti(C,N)-cBN composites sintered at different temperatures were studied, and their effects on the mechanical properties were investigated. The results show that when the sintering temperature increases from 1300 to 1500°C, the heat preservation time shortens, whereas the density and interface bonding strength of the composites increase. In addition, cBN particles can play the role of crack bridging and be pulled out when the composites fracture, improving the toughness of the Al 2 O 3 –Ti(C,N)–cBN composites. However, when the sintering temperature further rises to 1600°C, a new phase of TiB 2 forms, and the solid solubility of C and N in Ti(C,N) increases, leading to a decrease in density and mechanical properties. As a result, when the Al 2 O 3 –Ti(C,N)–cBN composite is sintered at 1500°C, its mechanical properties reach the maximum values of 21.5 GPa, 5.7 MPa m 1/2 , and 731 MPa for hardness, fracture toughness, and flexural strength, respectively.
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Journal of the Australian Ceramic Society
·
2023
·Vol. 59
·期 5
·1231-1239
·
IF 1.9
Zhang Mengwen,Jiang Binyang,Yang Lutong,Cao Na,Li Zhaosheng,Fan Lei,Yang Shoulei
The emerging oscillatory pressure sintering technology is used to prepare high-performance Al 2 O 3 -Ti(C,N) ceramic tools for high-speed cutting. By recording the displacement during sintering, the sintering shrinkage rate of the Al 2 O 3 -Ti(C,N) composite was calculated, and the stress exponent n and sintering activation energy Q were calculated according to creep theory to determine the densification mechanism. In addition, the evolution of phases, microstructure and hardness of the composite was also observed. Results show that during oscillatory pressure sintering process at 1400 °C and 1300 °C, the stress exponent of Al 2 O 3 -Ti(C,N) composite is around 2.2 and the sintering activation energy is 486 kJ mol −1 , indicating that the densification mechanism is a diffusion-controlled grain boundary sliding of Al 2 O 3 phase. Additionally, as the oscillatory pressure increases, the average grain size of the Al 2 O 3 decreases and the Vickers hardness increases. Hardness achieves the highest 22.7 GPa when the median oscillatory pressure is 70 MPa at 1400 °C, which is 1 GPa higher than that of static pressure of 70 MPa.
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International Journal of Applied Ceramic Technology
·
2023
·Vol. 20
·期 5
·2737-2746
·
IF 2.1
Zhaoping Hou,Xinhe Yang,Zihan Tian,Liangliang Liu
Porous Al 2 O 3 ceramic beads with a small-scale lamellar pore structure were prepared by the dripping-ice templating method. The densification behavior of lamellar walls and the attrition resistance of porous Al 2 O 3 beads were investigated. For the two-dimensional structural lamellar walls, the intrinsic pores shrunk, and the necking area grew during the sintering process, leading to the densification of lamellar walls and the shrinking of porous beads. In addition, the two-dimensional lamellar walls and three-dimensional Al 2 O 3 bulk are compared and possibilities of elaborating of the discrepancy in grain size and pore morphology are discussed. Attrition resistance was determined by a grinding test. The dominant attrition mechanism of porous Al 2 O 3 beads is abrasion. High sintering temperature led to a decrease in the attrition rate due to a wider necking area and denser pore walls.
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高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Minhao Shen,Renli Fu,Yunan Liu,Yunjia Hu,Yanlin Jiang,Zhe Zhao,Ming Liu
Inspired by the double-helix structure of biological DNA, low-volume fraction and high-strength Al 2 O 3 twisted honeycomb structures with characteristics similar to those of helical structures in the z -axis were prepared by digital light processing 3D printing technology. As the twist angle increased, the compressive strength of the fabricated Al 2 O 3 structure decreased, and the deformation mechanism of the Al 2 O 3 structures gradually changed from stretching-dominated to bending-dominated, which can be predicted by the Gibson–Ashby model. The relationship between the effective elastic modulus and the volume fraction that can be modified by varying the wall thickness was described by the Pabst–Gregorova exponential relationship. The compressive strength of the Al 2 O 3 structure with a twist angle of 0° can reach 62.4 MPa at a volume fraction of 13.3%, providing guidance to optimize lightweight structures of ceramics.
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高影响因子
POLYMER COMPOSITES
·
2023
·Vol. 44
·期 6
·3221-3231
·
IF 5.2
Zijian Lu,Wei Wu,Dietmar Drummer,Yi Wang,Chao Liu,Shuo Li,Xintong Zhao
It is of great significance to study new thermal conductivity filler in practical thermal management application. In this study, a multi-scale assembled thermal conductivity composite Al 2 O 3 -ZnO NWs/GO/EP was developed. The test results showed that the composite has good thermal conductivity and mechanical properties with low filler content. When the GO content is 1.5 wt% and the Al 2 O 3 -ZnO NWs content is 25 wt%, the thermal conductivity of the composites reaches 2.15 W/mK, which is improved by about 1032% compared with the pure epoxy resin, and the tensile strength of the composites is maintained at a high level. The problems of high filling capacity and poor mechanical properties of alumina filler were effectively solved. It provides a new idea for preparing the filled thermal conductivity composites with low filling capacity and high thermal conductivity.
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高影响因子
Molecular Catalysis
·
2023
·
IF 4.6
Sihao Shu,Zhongze Wang,Xing Zhang,Haonan Shi,Shangzhen Feng,Jixiang Chen
Al 2 O 3 supported Ni-Sn alloy (Ni/Sn atomic ratio of 6) and Ni 3 Sn, Ni 3 Sn 2 and Ni 3 Sn 4 intermetallic compounds (IMCs) were prepared by co-precipitation method for the deoxygenation of fatty acid methyl esters to produce hydrocarbons. In comparison with metallic Ni, the catalytic evaluation and methyl propionate-TPD/TPSR results reveal that Ni-Sn IMCs remarkably inhibit the decarbonylation/decarboxylation pathway, C-C bond hydrogenolysis and methanation while promote the hydrodeoxygenation pathway, subsequently enhancing the yield of aiming hydrocarbons. Therein, 20%Ni 3 Sn 2 /Al 2 O 3 has the best performance, and the hydrocarbons yield reach about 99% in the deoxygenation of methyl octanoate and methyl palmitate. We suggest that the geometric and electronic effects of Sn contribute the excellent performance of Ni-Sn IMCs, and there is synergetic effect between Ni and Sn sites for the activation of C-O/C=O bond, for which a suitable Ni-Sn atomic spacing is very important. Finally, the catalyst stability and deactivation were also investigated.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2019
·
IF 8.355
Renjing Zhang,Yanjian Wan,Jiali Peng,Gang Yao,Yunhong Zhang,Bo Lai
In this study, LaCoO 3 /Al 2 O 3 (LCA) was utilized as a heterogeneous catalyst to activate peroxymonosulfate (PMS) to degrade atrazine (ATZ). The structural properties of the catalysts were characterized by SEM, EDS, XRD, XPS and TPD. The effects of some key parameters (i.e., loadings of LCA, ATZ concentration, catalyst dosage, PMS concentration, initial pH and coexisting ions) were optimized. In addition, under the optimal conditions of 100 mg/L 23LCA, 100 mg/L PMS and initial solution pH 6.8, the removal rate and mineralization efficiency of ATZ (5 mg/L) reached 100% and 30.8%, respectively. The superiority of the 23LCA/PMS system was verified by two controlled experiments. After three cycles of experiments, the degradation effect of ATZ was within an acceptable range. The degradation intermediates of ATZ were detected by UPLC-QTOF-MS/MS, and the possible degradation pathway of ATZ was proposed. In addition, the presence of SO 4 − and HO was identified by quenching experiments and SO 4 − was verified as the predominant radical. Finally, based on the comprehensive analysis, a reasonable reaction mechanism of the 23LCA/PMS system was proposed. In a word, these results indicate that LCA can act as a highly efficient heterogeneous catalyst to activate PMS to degrade ATZ in water.
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危险品化学品经营许可证（带存储）