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Current understanding and applications of the cold sintering process

Tong Yu, Jiang Cheng, Lu Li, Benshuang Sun, Xujin Bao, Hongtao Zhang

《化学科学与工程前沿（英文）》 2019年 第13卷 第4期   页码 654-664 doi: 10.1007/s11705-019-1832-1

摘要： In traditional ceramic processing techniques, high sintering temperature is necessary to achieve fully dense microstructures. But it can cause various problems including warpage, overfiring, element evaporation, and polymorphic transformation. To overcome these drawbacks, a novel processing technique called “cold sintering process (CSP)” has been explored by Randall et al. CSP enables densification of ceramics at ultra-low temperature (≤300°C) with the assistance of transient aqueous solution and applied pressure. In CSP, the processing conditions including aqueous solution, pressure, temperature, and sintering duration play critical roles in the densification and properties of ceramics, which will be reviewed. The review will also include the applications of CSP in solid-state rechargeable batteries. Finally, the perspectives about CSP is proposed.

关键词： cold sintering process     processing variables     solid-state rechargeable batteries    

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Fabrication of form stable NaCl-Al2O3 composite for thermal energy storage by cold sintering process

Bilyaminu Suleiman, Qinghua Yu, Yulong Ding, Yongliang Li

《化学科学与工程前沿（英文）》 2019年 第13卷 第4期   页码 727-735 doi: 10.1007/s11705-019-1823-2

摘要： A form stable NaCl-Al O (50-50 wt-%) composite material for high temperature thermal energy storage was fabricated by cold sintering process, a process recently applied to the densification of ceramics at low temperature ˂ 300°C under uniaxial pressure in the presence of small amount of transient liquid. The fabricated composite achieved as high as 98.65% of the theoretical density. The NaCl-Al O composite also retained the chloride salt without leakage after 30 heating-cooling cycles between 750°C–850°C together with a holding period of 24 h at 850°C. X-ray diffraction measurements indicated congruent solubility of the alumina in chloride salt, excellent compatibility of NaCl with Al O , and chemical stability at high temperature. Structural analysis by scanning electron microscope also showed limited grain growth, high density, uniform NaCl distribution and clear faceted composite structure without inter-diffusion. The latent heat storage density of 252.5 J/g was obtained from simultaneous thermal analysis. Fracture strength test showed high sintered strength around 5 GPa after 50 min. The composite was found to have fair mass losses due to volatilization. Overall, cold sintering process has the potential to be an efficient, safe and cost-effective strategy for the fabrication of high temperature thermal energy storage materials.

关键词： cold sintering process     composite fabrication     thermal energy storage     phase change materials    

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Laser sintering of Cu nanoparticles on PET polymer substrate for printed electronics at different wavelengthsand process conditions

Juan Carlos HERNANDEZ-CASTANEDA, Boon Keng LOK, Hongyu ZHENG

《机械工程前沿（英文）》 2020年 第15卷 第2期   页码 303-318 doi: 10.1007/s11465-019-0562-x

摘要： This study explores the feasibility of different laser systems to sinter screen-printed lines from nonconductive copper nanoparticles (Cu NPs) on polyethylene terephthalate polymer film. These materials are commonly used in manufacturing functional printed electronics for large-area applications. Here, optical and thermal characterization of the materials is conducted to identify suitable laser sources and process conditions. Direct diode (808 nm), Nd:YAG (1064 nm and second harmonic of 532 nm), and ytterbium fiber (1070 nm) lasers are explored. Optimal parameters for sintering the Cu NPs are identified for each laser system, which targets low resistivity and high processing speed. Finally, the quality of the sintered tracks is quantified, and the laser sintering mechanisms observed under different wavelengths are analyzed. Practical considerations are discussed to improve the laser sintering process of Cu NPs.

关键词： laser sintering     copper nanoparticles     printed electronics    

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Effects of EGR on combustion process of DI diesel engine during cold start

PENG Haiyong, CUI Yi, SHI Lei, DENG Kangyao

《能源前沿（英文）》 2008年 第2卷 第2期   页码 202-210 doi: 10.1007/s11708-008-0038-x

摘要： Experiments on the effects of external and internal exhaust gas recirculation (EGR) on combustion and emission performance during a cold start process were investigated in a 135 single-cylinder DI diesel engine. Combustion was improved during the initial ignition cycles by introducing internal or external EGR. The addition of an appropriate amount of internal or external EGR can promote the combustion stability significantly. However, excessive amounts of external EGR could lead to extremely unstable combustion or even misfiring. An appropriate amount of internal or external EGR decreased smoke opacity effectively during a cold start. External EGR reduced NO emissions effectively while internal EGR led to an increase in NO emissions due to thermal effects.

关键词： opacity     combustion     excessive     NO     process    

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Effect of catalyst layer mesoscopic pore-morphology on cold start process of PEM fuel cells

Ahmed Mohmed DAFALLA, Fangming JIANG

《能源前沿（英文）》 2021年 第15卷 第2期   页码 460-472 doi: 10.1007/s11708-021-0733-4

摘要： Water transport is of paramount importance to the cold start of proton exchange membrane fuel cells (PEMFCs). Analysis of water transport in cathode catalyst layer (CCL) during cold start reveals the distinct characteristics from the normal temperature operation. This work studies the effect of CCL mesoscopic pore-morphology on PEMFC cold start. The CCL mesoscale morphology is characterized by two tortuosity factors of the ionomer network and pore structure, respectively. The simulation results demonstrate that the mesoscale morphology of CCL has a significant influence on the performance of PEMFC cold start. It was found that cold-starting of a cell with a CCL of less tortuous mesoscale morphology can succeed, whereas starting up a cell with a CCL of more tortuous mesoscale morphology may fail. The CCL of less tortuous pore structure reduces the water back diffusion resistance from the CCL to proton exchange membrane (PEM), thus enhancing the water storage in PEM, while reducing the tortuosity in ionomer network of CCL is found to enhance the water transport in and the water removal from CCL. For the sake of better cold start performance, novel preparation methods, which can create catalyst layers of larger size primary pores and less tortuous pore structure and ionomer network, are desirable.

关键词： cold start     energy conversion     fuel cells     mesoscale morphology     tortuosity     water management    

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Development of lunar regolith composite and structure via laser-assisted sintering

《机械工程前沿（英文）》 doi: 10.1007/s11465-021-0662-2

摘要： Aiming at the exploration and resource utilization activities on the Moon, in situ resource utilization and in situ manufacturing are proposed to minimize the dependence on the ground transportation supplies. In this paper, a laser-assisted additive manufacturing process is developed to fabricate lunar regolith composites with PA12/SiO2 mixing powders. The process parameters and composite material compositions are optimized in an appropriate range through orthogonal experiments to establish the relationship of process–structure–property for lunar regolith composites. The optimal combination of composite material compositions and process parameters are mixing ratio of 50/50 in volume, laser power of 30 W, scanning speed of 3500 mm/s, and scanning hatch space of 0.2 mm. The maximum tensile strength of lunar regolith composites reaches 9.248 MPa, and the maximum depth of surface variation is 120.79 μm, which indicates poor powder fusion and sintering quality. Thereafter, the mechanical properties of laser-sintered lunar regolith composites are implemented to the topology optimization design of complex structures. The effectiveness and the feasibility of this laser-assisted process are potentially developed for future lightweight design and manufacturing of the solar panel installed on the lunar rover.

关键词： in situ manufacturing     laser-assisted powder fusion process     mechanical properties     topological structure design    

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Preparation and microstructure analysis of Fe-doped PbTiO ceramic

QIANG Liangsheng, MA Jing, CHU Jia, ZHANG Xiaohong

《化学科学与工程前沿（英文）》 2008年 第2卷 第2期   页码 140-144 doi: 10.1007/s11705-008-0021-4

摘要： Fe-doped PbTiO (PT) powder and bulk materials were prepared successfully by sol-gel technique and a subsequent sintering process using Fe (CH) as a dopant agent. The effects of pH and temperature on the Fe-doped PT system were investigated. Thermogravimetry/differential thermal analysis (TG/DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to analyze the composition and the microstructure of the PT ceramics. The results indicated that the thermal decomposition of xerogel included three stages: volatilization of adsorption water and organic composition, oxygenolysis of -butyl and acetate, and transformation of the crystalline phase. Well-stabilized collosol and gel could be obtained at 60°C and pH = 4.5. It was found that PbTiO, PbFeO, and TiO crystalline appeared in the Fe-doped PT system when the mass fraction of the dopant Fe was 0.03%. Furthermore, from STM analysis, it could be seen that the grain size of doped PT ceramics was homogeneous and about 1–2 ?m, and the pore of the PT ceramic was small. As a result, the PT ceramic had high tightness.

关键词： homogeneous     Thermogravimetry/differential thermal     tightness     oxygenolysis     sintering process    

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Stabilization of hexavalent chromium with pretreatment and high temperature sintering in highly contaminated

Haiyan Mou, Wenchao Liu, Lili Zhao, Wenqing Chen, Tianqi Ao

《环境科学与工程前沿（英文）》 2021年 第15卷 第4期 doi: 10.1007/s11783-020-1353-7

摘要： Abstract • Separate reduction and sintering cannot be effective for Cr stabilization. • Combined treatment of reduction and sintering is effective for Cr stabilization. • Almost all the Cr in the reduced soil is residual form after sintering at 1000°C. This study explored the effectiveness and mechanisms of high temperature sintering following pre-reduction with ferric sulfate (FeSO4), sodium sulfide (Na2S), or citric acid (C6H8O7) in stabilizing hexavalent chromium (Cr(VI)) in highly contaminated soil. The soil samples had an initial total Cr leaching of 1768.83 mg/L, and Cr(VI) leaching of 1745.13 mg/L. When FeSO4 or C6H8O7 reduction was followed by sintering at 1000°C, the Cr leaching was reduced enough to meet the Safety Landfill Standards regarding general industrial solid waste. This combined treatment greatly improved the stabilization efficiency of chromium because the reduction of Cr(VI) into Cr(III) decreased the mobility of chromium and made it more easily encapsulated in minerals during sintering. SEM, XRD, TG-DSC, and speciation analysis indicated that when the sintering temperature reached 1000°C, almost all the chromium in soils that had the pre-reduction treatment was transformed into the residual form. At 1000°C, the soil melted and promoted the mineralization of Cr and the formation of new Cr-containing compounds, which significantly decreased subsequent leaching of chromium from the soil. However, without reduction treatment, chromium continued to leach from the soil even after being sintered at 1000°C, possibly because the soil did not fully fuse and because Cr(VI) does not bind with soil as easily as Cr(III).

关键词： Chromium     Heavy contaminated soil     Reduction     Sintering     Stabilization     Speciation    

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Two-dimensional modeling of sintering of a powder layer on top of nonporous substrate

Tiebing CHEN, Yuwen ZHANG,

《机械工程前沿（英文）》 2010年 第5卷 第2期   页码 143-148 doi: 10.1007/s11465-010-0006-0

摘要： Selective laser sintering (SLS) of a two-component metal powder layer on the top of multiple sintered layers by a moving Gaussian laser beam is modeled. The loose metal powder layer is composed of a powder mixture with significantly different melting points. The physical model that accounts the shrinkage induced by melting is described by using a temperature-transforming model. The effects of the porosity and the thickness of the atop loose powder layer with different numbers of the existing sintered metal powder layers below on the sintering process are numerically investigated. The present work will provide a better understanding to simulate much more complicated three-dimensional SLS process.

关键词： laser     sintering     melting     solidification     heat transfer    

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A novel approach to preparing ultra-lightweight ceramsite with a large amount of fly ash

Sen Liu, Congren Yang, Wei Liu, Longsheng Yi, Wenqing Qin

《环境科学与工程前沿（英文）》 2020年 第14卷 第4期 doi: 10.1007/s11783-020-1241-1

摘要： •Ultra-lightweight ceramsite is prepared with 80% fly ash. •SiO2, Al2O3, and flux contents significantly influence the performance of ceramsite. •The expansion of ceramsite is caused by the formation of a dense glaze and gas. •The bulk density of ultra-lightweight ceramsite is only 340 kg/m3. The disposal of fly ash has become a serious problem in China due to its rapid increase in volume in recent years. The most common method of fly ash disposal is solidification-stabilization-landfill, and the most common reuse is low-value-added building materials. A novel processing method for preparing ultra-lightweight ceramsite with fly ash was developed. The results show that the optimal parameters for preparation of ultra-lightweight ceramsite are as follows: mass ratio of fly ash:kaolin:diatomite= 80:15:5, preheating temperature of 800°C, preheating time of 5 min, sintering temperature of 1220°C, and sintering time of 10 min. The expansion agent is perlite, at 10 wt.% addition. Finally, a ceramsite with bulk density of 340 kg/m3, particle density of 0.68 g/cm3, and cylinder compressive strength of 1.02 MPa was obtained. Because of its low density and high porosity, ultra-lightweight ceramsite has excellent thermal insulation performance, and its strength is generally low, so it is usually used in the production of thermal insulation concrete and its products. The formation of a liquid-phase component on the surface, and generation of a gas phase inside ceramsite during the sintering process, make it possible to control the production of the suitable liquid phase and gas in this system, resulting in an optimization of the expansion behavior and microstructure of ceramsite. These characteristics show the feasibility of industrial applications of fly ash for the production of ultra-lightweight ceramsite, which could not only produce economic benefits, but also conserve land resources and protect the environment.

关键词： Fly ash     Ultra-lightweight ceramsite     Expansion mechanism     Sintering process    

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review on technologies with electricity generation potentials using liquified natural gas regasification cold

《能源前沿（英文）》 2023年 第17卷 第3期   页码 332-379 doi: 10.1007/s11708-023-0863-y

摘要： In modern times, worldwide requirements to curb greenhouse gas emissions, and increment in energy demand due to the progress of humanity, have become a serious concern. In such scenarios, the effective and efficient utilization of the liquified natural gas (LNG) regasification cold energy (RCE), in the economically and environmentally viable methods, could present a great opportunity in tackling the core issues related to global warming across the world. In this paper, the technologies that are widely used to harness the LNG RCE for electrical power have been reviewed. The systems incorporating, the Rankine cycles, Stirling engines, Kalina cycles, Brayton cycles, Allam cycles, and fuel cells have been considered. Additionally, the economic and environmental studies apart from the thermal studies have also been reviewed. Moreover, the discussion regarding the systems with respect to the regassification pressure of the LNG has also been provided. The aim of this paper is to provide guidelines for the prospective researchers and policy makers in their decision making.

关键词： liquified natural gas     cold energy     power generation    

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Optimization of cold-end system of thermal power plants based on entropy generation minimization

《能源前沿（英文）》 2022年 第16卷 第6期   页码 956-972 doi: 10.1007/s11708-021-0785-5

摘要： Cold-end systems are heat sinks of thermal power cycles, which have an essential effect on the overall performance of thermal power plants. To enhance the efficiency of thermal power plants, multi-pressure condensers have been applied in some large-capacity thermal power plants. However, little attention has been paid to the optimization of the cold-end system with multi-pressure condensers which have multiple parameters to be identified. Therefore, the design optimization methods of cold-end systems with single- and multi-pressure condensers are developed based on the entropy generation rate, and the genetic algorithm (GA) is used to optimize multiple parameters. Multiple parameters, including heat transfer area of multi-pressure condensers, steam distribution in condensers, and cooling water mass flow rate, are optimized while considering detailed entropy generation rate of the cold-end systems. The results show that the entropy generation rate of the multi-pressure cold-end system is less than that of the single-pressure cold-end system when the total condenser area is constant. Moreover, the economic performance can be improved with the adoption of the multi-pressure cold-end system. When compared with the single-pressure cold-end system, the excess revenues gained by using dual- and quadruple-pressure cold-end systems are 575 and 580 k$/a, respectively.

关键词： cold-end system     entropy generation minimization     optimization     economic analysis     genetic algorithm (GA)    

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Application of cold spraying for flux-free brazing of aluminium alloy 6060

Kirsten BOBZIN, Lidong ZHAO, Thomas SCHLAEFER, Thomas WARDA,

《机械工程前沿（英文）》 2010年 第5卷 第3期   页码 256-260 doi: 10.1007/s11465-010-0095-9

摘要： In the present study, samples of aluminium alloy 6060 were coated by cold spraying with a powder of brazing alloy Al12Si. The influence of the process gas temperature on particle velocities and coating build-up was investigated. The coated samples were heat-treated in air and under argon atmosphere to investigate the wetting behaviour of the deposited Al12Si and the diffusion processes between Al12Si coatings and substrates. Coated samples were brazed flux-free under argon atmosphere by an induction heating system. The microstructure of the coated, heat-treated, and brazed samples was investigated. The shear strength of the brazed joints was determined. The results show that the brazing alloy Al12Si could be very well deposited on the substrate by cold spraying. The particle velocity increased with increasing process temperature. Correspondingly, the thickness of Al12Si coatings increased with increasing process temperature. The heat treatments showed that a very good metallurgical bond between the Al12Si coatings and the substrate could be realized by the deposition using cold spraying. The coated samples could be well brazed without fluxes. The coating thickness and overlap width influenced the shear strength of the brazed joints. The highest shear strength of brazed joints amounts to 80 MPa.

关键词： aluminium alloy     flux-free brazing     cold spraying     shear strength    

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A fully solid-state cold thermal energy storage device for car seats using shape-memory alloys

《能源前沿（英文）》 2023年 第17卷 第4期   页码 504-515 doi: 10.1007/s11708-022-0855-3

摘要： Thermal energy storage has been a pivotal technology to fill the gap between energy demands and energy supplies. As a solid-solid phase change material, shape-memory alloys (SMAs) have the inherent advantages of leakage free, no encapsulation, negligible volume variation, as well as superior energy storage properties such as high thermal conductivity (compared with ice and paraffin) and volumetric energy density, making them excellent thermal energy storage materials. Considering these characteristics, the design of the shape-memory alloy based the cold thermal energy storage system for precooling car seat application is introduced in this paper based on the proposed shape-memory alloy-based cold thermal energy storage cycle. The simulation results show that the minimum temperature of the metal boss under the seat reaches 26.2 °C at 9.85 s, which is reduced by 9.8 °C, and the energy storage efficiency of the device is 66%. The influence of initial temperature, elastocaloric materials, and the shape-memory alloy geometry scheme on the performance of car seat cold thermal energy storage devices is also discussed. Since SMAs are both solid-state refrigerants and thermal energy storage materials, hopefully the proposed concept can promote the development of more promising shape-memory alloy-based cold and hot thermal energy storage devices.

关键词： shape-memory alloy (SMA)     elastocaloric effect (eCE)     cooled seat     cold thermal energy storage    

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Tracking in urban wastewater treatment plants in a cold region: Occurrence, species and infectivity

《环境科学与工程前沿（英文）》 2022年 第16卷 第9期 doi: 10.1007/s11783-022-1533-8

摘要：

• Cryptosporidium in WWTPs in a cold region was investigated in different seasons.

关键词： WWTPs     Cryptosporidium     Occurrence     Species     Infectivity     Low temperature    

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标题 作者 时间 类型 操作

Current understanding and applications of the cold sintering process

Tong Yu, Jiang Cheng, Lu Li, Benshuang Sun, Xujin Bao, Hongtao Zhang

期刊论文

Fabrication of form stable NaCl-Al2O3 composite for thermal energy storage by cold sintering process

Bilyaminu Suleiman, Qinghua Yu, Yulong Ding, Yongliang Li

期刊论文

Laser sintering of Cu nanoparticles on PET polymer substrate for printed electronics at different wavelengthsand process conditions

Juan Carlos HERNANDEZ-CASTANEDA, Boon Keng LOK, Hongyu ZHENG

期刊论文

Effects of EGR on combustion process of DI diesel engine during cold start

PENG Haiyong, CUI Yi, SHI Lei, DENG Kangyao

期刊论文

Effect of catalyst layer mesoscopic pore-morphology on cold start process of PEM fuel cells

Ahmed Mohmed DAFALLA, Fangming JIANG

期刊论文

Development of lunar regolith composite and structure via laser-assisted sintering

期刊论文

Preparation and microstructure analysis of Fe-doped PbTiO ceramic

QIANG Liangsheng, MA Jing, CHU Jia, ZHANG Xiaohong

期刊论文

Stabilization of hexavalent chromium with pretreatment and high temperature sintering in highly contaminated

Haiyan Mou, Wenchao Liu, Lili Zhao, Wenqing Chen, Tianqi Ao

期刊论文

Two-dimensional modeling of sintering of a powder layer on top of nonporous substrate

Tiebing CHEN, Yuwen ZHANG,

期刊论文

A novel approach to preparing ultra-lightweight ceramsite with a large amount of fly ash

Sen Liu, Congren Yang, Wei Liu, Longsheng Yi, Wenqing Qin

期刊论文

review on technologies with electricity generation potentials using liquified natural gas regasification cold

期刊论文

Optimization of cold-end system of thermal power plants based on entropy generation minimization

期刊论文

Application of cold spraying for flux-free brazing of aluminium alloy 6060

Kirsten BOBZIN, Lidong ZHAO, Thomas SCHLAEFER, Thomas WARDA,

期刊论文

A fully solid-state cold thermal energy storage device for car seats using shape-memory alloys

期刊论文

Tracking in urban wastewater treatment plants in a cold region: Occurrence, species and infectivity

期刊论文