CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Zhao Li,Xingyun Jin,Chunfeng Hu,Bo Dai,Yong Ren,Fang Xu,Yong Zhao,Xingwu Yuan
In this work, conventional sintering, hot-pressing sintering, and spark plasma sintering techniques were utilized to simulate the thermal field, thermal-stress field, and thermal-stress-electric field, respectively. The effects of these fields on the microstructure and cation distribution of the (Mg 0.1 Mn 0.1 Co 0.1 Ni 0.2 Ti 0.1 Cu 0.1 Zn 0.2 )Fe 2.1 O 4 ferrite (HEF) material were comprehensively analyzed. The results indicate that in the temperature range of 1000–1100 °C, the thermal field provides the driving force for sintering, promotes grain growth (average particle size: 2→7 μm), and increases crystallinity degree. The stress field brings the particles into close contact with each other, facilitates diffusion, and delays grain growth (0.5→5 μm). The electric field reduces grain boundary energy, causes mass transfer, and makes the grains finer (0.5→0.7 μm) and more uniform. Mathematical model analysis reveals that the thermal field is beneficial to the random distribution of cations, which yields an inversion degree (γ) of about 2/3 and increases the configuration entropy of HEF. The stress field leads to lattice distortion, permits ions with larger radius to occupy tetrahedral positions, and changes the cell parameters and oxygen position parameter of HEF. Finally, the interaction between electric field and crystal charges increases the electrostatic field energy, which promotes the formation of positive spinel structure and maximizes the crystal field stability energy. X-ray photoelectron spectra, Raman spectra, and change in lattice constant confirm the rationality of the mathematical model, and can be used to establish the model of the crystal structure under field effects.
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
高影响因子
Energy & Environmental Materials
·
2022
·Vol. 6
·期 3
·e12375
·
IF 13.443
Zihan Xu,Wenxin Fan,Jinghua Duan,Yanzhi Xia,Zhihong Nie,Kunyan Sui
The 3D shape-changing hydrogels are highly pursued for numerous applications. However, up to now, the construction of complex 3D shape-changing hydrogels remains a challenge. The reported design strategies are mainly applied to fabricate 2D ones by introducing anisotropic microstructures into hydrogel sheets/membranes. Herein, we present a convenient photolithography strategy for constructing complex 3D shape-changing hydrogels by simultaneously modulating anisotropic microstructures and internal stress fields of gel sheets. When the precursor solution containing ultraviolet (UV) absorber is irradiated by single-side UV light, the attenuated polymerization rate can cause the generation of asymmetric internal stress field in the resulting hydrogel sheet. In the meantime, the directional diffusion of unpolymerized monomers allows for the formation of vertical gradient structure within hydrogel. Therefore, by applying different photomasks to modulate the local gradient structures and internal stress fields of the gel sheets, they can spontaneously transform into various complex 3D shape-changing hydrogels in the air. Response to the external stimuli, these 3D shape-changing hydrogels (e.g., fighter plane, birdie, and multi-storey origami lattices) can deform in a novel 3D 1 -to-3D 2 -to-3D 3 mode. This new design strategy contributes to the development of complex biomedical implants and soft robotics.
研究领域:
材料科学
·
生物医学工程
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL CROPS AND PRODUCTS
·
2024
·
IF 5.6
Xiaoran Li,Kehui Cen,Jinjin Li,Chu Wang,Dongxia Jia,Dengyu Chen
In this study, cellulose and lignin were subjected to co-pyrolysis for the production of syngas. For the pyrolysis experiments, three influencing factors were selected using a response surface method: pyrolysis temperature (400–800 °C), residence time (5–30 min), and lignin mass percentage (0–100 wt%). At a pyrolysis temperature of 477.4 °C, a residence time of 30 min, and a lignin mass percentage of 50 wt%, the actual syngas yield was 77.2 % higher than the theoretical value for the co-pyrolysis. In addition, the hydrogen volume fraction was improved by up to 24.87 % because of the interaction between cellulose and lignin during their co-pyrolysis (pyrolysis temperature of 800 °C, residence time of 17.5 min, lignin mass percentage of 80.65 wt%). Finally, the hydrogen formation process was simulated, using reactive force field molecular dynamics. The results showed that hydrogen molecules began to appear at a simulation time of 0.479 ns and then gradually increased in number with progressing simulation time. In addition, the hydrogen generation pathways were obtained by this simulation method. This study provides a data foundation for optimizing syngas and hydrogen production from biomass.
研究领域:
能源与燃料
·
化学工程
·
生物质能
✓ 已验证
产品关联
DOI
高影响因子
CARBON
·
2024
·
IF 10.5
Q. Chen,I.M. De Cachinho Cordeiro,W. Yang,A.C.Y. Yuen,T.B.Y. Chen,W. Wang,W. Yang,G.H. Yeoh,R.K.K. Yuen
Graphdiyne (GDY) is an emerging two-dimensional carbon allotrope comprising unique sp 1 and sp 2 hybridisation, which has attracted extensive investigation into various applications, especially as battery component materials owing to its excellent electromechanical properties. However, GDY's thermal stability and oxidation behaviour have yet to be evaluated, which is crucial to safety in high-energy applications. The present study characterised the thermophysical properties of GDY via reactive molecular dynamics (MD-ReaxFF) and experimental measurement. The oxidation kinetics and decomposition behaviour were elucidated and benchmarked with graphene (GP) and graphyne (GY) to investigate the correlation between thermal stability and morphology of carbon nanomaterials. The simulation results revealed the initial oxidation mechanism of GDY sheets, where the cleavage of C–C bonds was observed at the acetylenic chain and could be identified as the weak spots of the structural stability. As for oxidation kinetics, GDY's experimental and numerical activation energy was found to be 173.1 and 133 kJ/mol, which is lower than 220.8 kJ/mol of GP. The current work pioneer investigated the thermal stability of GDY using both experimental and numerical approaches. Meanwhile, different oxidation mechanisms between GP and GDY were distinguished and demonstrated in detail.
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
EUROPEAN PHYSICAL JOURNAL E
·
2014
·Vol. 37
·期 9
·1-7
·
IF 2.183
Zhang Yongjian,Qian Yimeng,Liu Zhengtang,Li Zhiguang,Zang Duyang
Abstract. The cracking behavior accompanied with the drying of colloidal droplets containing polytetrafluoroethylene (PTFE) nanoparticles was studied. During evaporation, due to the stretching effect of the liquid zone, the receding wet front leads to the formation of radialized surface wrinkling in the gel zone. This indicates the building of a macroscopic stress field with a similar distribution. As a result, the cracks in the deposited films are in a radial arrangement. The propagation velocity of the cracks depends on the thickness of the film, ∼ H
3/5 . In addition, sodium dodecylsulfate (SDS) additives can be used to tune crack behavior by causing a reduction of the capillary force between particles. The results highlight the significance of the receding wet front in building the drying deposition stress field and may be helpful in other fields related to drying and cracking processes. Graphical abstract
研究领域:
胶体科学
·
软物质物理
·
材料表面工程
·
干燥动力学
·
薄膜沉积
✓ 已验证
DOI
高影响因子
npj Flexible Electronics
·
2023
·Vol. 7
·期 1
·1-9
·
IF 14.6
Shang Chao,Xu Qunhui,Liang Nengmin,Zhang Jianpeng,Li Lu,Peng Zhengchun
Tactile sensing has been a key challenge in robotic haptics. Inspired by how human skin sense the stress field with layered structure and distributed mechanoreceptors, we herein propose a design for modular multi-parameter perception electronic skin. With the stress field sensing concept, complex tactile signals can be transformed into field information. By analyzing the stress field, the real-time three-dimensional forces can be resolved with 1.8° polar angle resolution and 3.5° azimuthal angle resolution (achieved up to 71 folds of improvement in spatial resolution), we can also detect the hardness of object in contact with the electronic skin. Moreover, we demonstrate random assembly of the sensing arrays and integration of our electronic skin onto differently curved surfaces do not lead to any measurement variation of the stress field. This result reveals that the sensing elements in our electronic skin system can be modularly made and exchanged for specific applications.
研究领域:
机器人学
·
生物医学工程
·
材料科学
✓ 已验证
DOI
高影响因子
ENERGY & FUELS
·
2024
·
IF 5.2
Yuchuan Feng,Penghui Wang,Nana Wang,Xin Guo,Suxia Ma
Reactive force field molecular dynamics (ReaxFF MD) simulation and experiments were employed to deeply reveal the sintering mechanism of Fe2O3 particles during iron-based chemical looping combustion. The sintering process of Fe2O3 particles was simulated at different temperatures (973–1273 K). The results showed that the temperature increase has limited effect on the structure of Fe2O3 particles and slightly increases the atomic irregularity. The sintering process of Fe2O3 particles can be divided into three stages: the proximity phase, rapid formation, and slow growth of the sintering neck. The temperature increase significantly promotes the sintering process of Fe2O3 particles. The mean-square displacement and Arrhenius equations were used to study the atomic diffusion properties of Fe2O3 particles. The diffusion activation energy of surface atoms is lower than that of inner atoms, implying that the surface atoms have stronger diffusion ability. With the increase of temperature, more Fe atoms diffuse toward the interface of Fe2O3 particles. Increasing the temperature can accelerate the diffusion and enrichment of surface atoms, especially Fe, toward the sintering neck region, resulting in more serious sintering of Fe2O3 particles. ReaxFF MD simulation is in good agreement with the experimental results. Inhibiting the atomic diffusion is the key to improving the antisintering ability of Fe2O3 oxygen carriers.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2025
·Vol. 108
·期 11
·e70097
·
IF 3.8
Kexuan Zhao,Pengrong Ren,Yang Yang,Jianhui Jia,Amei Zhang,Hongliang Du,Xin Wang
Sodium bismuth titanate (BNT)-based lead-free piezoelectric ceramics exhibit favorable electrical properties; however, the thermal depolarization effect limits their operational temperature range. Traditional chemical doping methods encounter difficulties in enhancing the depolarization temperature ( T d ) while preserving piezoelectric properties. In this work, magnesium oxide (MgO) was incorporated into 0.845Na 0.5 Bi 0.5 TiO 3 –0.055BaTiO 3 –0.1Li 0.5 Bi 0.5 TiO 3 (BNLT) ceramics to construct a zero to three composites. The difference in thermal expansion coefficients between the secondary phase and BNLT resulted in a localized stress field, which significantly delayed the thermal depolarization of the BNLT ceramics. Phase and microstructural analyses revealed the formation of a Mg 2 TiO 4 phase, which was distributed at the grain boundaries of the BNLT matrix. Electrical performance tests demonstrated that the T d increased from 61°C to 89.4°C with the addition of MgO. Assessment of interplanar spacing using transmission electron microscopy indicated the presence of tensile strain, which is proposed to stabilize the ferroelectric phase and enhance T d . Furthermore, the properties of composite ceramics BNLT: x %MgO, BNLT: y %Si 3 N 4 , and BNLT: z %Al 2 O 3 , each characterized by different thermal expansion coefficients of the secondary phase, were compared to validate the proposed mechanism.
✓ 已验证
产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2025
·
IF 6.9
Junjie Zhou,Shawei Tang,Jin Hu
Utilizing the oxide layer of carbon steel as an anti-corrosion protective layer is an environmentally friendly and cost-effective strategy. In this paper, a novel pressure swing oxidation (PSO) method was used to fabricate an oxide layer on the surface of Q235B, and the limiting effect of PSO on oxidation was presented using a reactive force field (ReaxFF). The surface characteristics and corrosion resistance of the oxide layers formed at varying temperature, as well as the different stage of PSO were investigated, and the formation mechanism of the oxide layer was discussed in detail. It can be found that the PSO process intensively affects the thickness, morphology and surface roughness along with phase composition of the oxide layers, which further influences the corrosion resistance. After the oxidation treatment, the corrosion current density of the treated sample was 3.31 × 10 −7 A·cm −2 which was reduced by about one order of magnitude in comparison with untreated Q235B. At the same time, an ultra-long passivation zone appeared in the corresponding polarization curve. Moreover, the impedance modulus at 0.01 Hz reached 1.29 × 10 6 Ω·cm 2 .
研究领域:
材料科学
·
腐蚀工程
·
表面工程
·
冶金学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Ruiji Zhang,Fangwei Guo,Wenchen Zhang,Fei Pan,Xing Zhang
Ceramics containing profiled fiber-like additives (nanotubes, whiskers, etc.) show high mechanical properties. However, the toughening mechanism is debated due to its complex multi-scale microstructure. In this work, ZrB 2 (Z)-20 vol%SiC(S) spiral fibers (ZS sf ) were prepared by liquid rope effect and non-solvent induced phase separation, while quantitative relation of mechanical properties and structure were investigated by using SEVNB with femtosecond lasers and in-situ 3D-XRM simulation. The ZrB 2 -SiC composites with hierarchy ZS sf exhibited a ∼60 % increase in fracture toughness (5.45 MPa m 1/2 ) compared with blank composites, while the toughening efficiency of the hierarchy ZS sf increased over 2 times compared to the 1D and 2D toughening additives. The ZS sf with a thin graphite-like layer and spiral structure with hierarchy pores provided a torsional release effect that changed brittle fracture to the pseudoplastic fracture, where topological interlocking of 3D crimped structure hindered rapid cracking propagation. Additionally, the enhanced toughness was attributed to the uniform reconstruction of the stress field induced by hierarchical inner pores. The preserved 3D topological interlocking and uniform stress reconstruction lead to the highly stable fracture toughness of the ZS sf composites up to 1500 °C.
研究领域:
材料科学
·
力学
·
陶瓷工程
✓ 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）