JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2025
·Vol. 109
·期 1
·e70365
·
IF 3.8
Huangshuai Zhang,Zhenting Zhu,Yu Ma,Zihao Yang,Zhe Chen,Fengshi Li,Hang Zhang
The nanoporous skeleton structure of alumina aerogel gives it a series of excellent properties, but it also greatly reduces its mechanical properties and thermal stability, which severely restricts its practical application. To address this challenge, herein we propose to simultaneously improve the thermal and mechanical properties of alumina aerogel by reinforcing the matrix with bimodal-scale whiskers, namely microscale SiC whisker (SiC MW ) and nanoscale mullite whisker (Mullite NW ), through an efficient vacuum freeze-drying process. The prepared SiC MW /Mullite NW /Al 2 O 3 aerogel composites are crack-free, with a uniform microstructure, a well-developed mesoporous network featuring ink-bottle-type pores, low density, and high specific surface area. The whiskers are well-bonded with the alumina matrix. At room temperature, the SiC MW /Mullite NW /Al 2 O 3 composite has low thermal conductivity, which increases with the SiC MW content. At high temperatures (1400°C), Mullite NW inhibits the transformation of the alumina matrix into dense α-Al 2 O 3 , thus helping retain the nanoporous skeleton. Combined with the infrared shielding effect of SiC MW , the composites exhibit superior thermal insulation and stability. Moreover, due to the effective inhibition of SiC MW and Mullite NW on microcrack initiation and propagation, the mechanical properties are significantly enhanced. This study presents an effective strategy to prepare high-performance alumina aerogel composites for potential practical applications and commercialization.
研究领域:
材料科学
·
陶瓷
·
热工工程
·
纳米材料
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复合材料
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产品关联
DOI
高影响因子
International Journal of Minerals Metallurgy and Materials
·
2020
·Vol. 27
·期 5
·687-692
·
IF 1.713
Chen Zhang-lin,Liu Kai,Yuan Xuan-yi,Chen Ke-xin
Nitrogen-rich Eu 2+ -doped Ca-α-SiAlON phosphors (Ca m /2− x Si 12− m−n Al m+n O n N 16− n : x Eu) were synthesized by a freeze-drying assisted combustion synthesis (CS) route. Fast-synthesized products with high purity and uniform particle morphology were confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The analysis of lattice parameters by comparison with empirical equations showed that the as-prepared phosphors had low oxygen content. A series of samples were prepared according to the stoichiometry of Ca m /2−0.08 Si 12− m Al m N 16 :0.08Eu for further research. The influences of m value on the luminescence properties were investigated in detail. As m increased, a redshift phenomenon was observed in both the excitation and emission spectra. First-principle electronic structure calculations showed that the 3d energy level of Ca played an important role in the occurrence of the redshift phenomenon.
研究领域:
材料科学
·
光学
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DOI
高影响因子
INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS
·
2020
·
IF 3.407
Weiqiang Hu,Zhi Dong,Hui Wang,Tansir Ahamad,Zongqing Ma
Oxide-dispersion-strengthened (ODS) tungsten based alloys with high performance were synthesized by optimized freeze-drying with PVP and PEG polymer dispersant additives and subsequent low temperature sintering . The pre-freezing principle developed firstly in our work shows that fast cooling rate and polymer dispersant additives contribute to the refinement and uniformity of precursor powders. The optimized freeze-dried W-Y 2 O 3 composite powders possess an average grain size of 9 nm, which can be attributed to the steric hindrance provided by polymer dispersants during freeze-drying and voids left by the decomposition of polymer dispersants during calcination . After sintering at low temperature, the W-Y 2 O 3 alloys have ultrafine W grain (210 nm) and nano second phase particles (<50 nm) dispersed in W matrix while maintaining a high relative density of 97.8%. These factors mentioned above lead to the microhardness and compressive strength as high as 721 ± 31 HV 0.2 , 814 MPa respectively, accompanied by a high total deformation plasticity of above 50%. These results indicate that the optimized freeze-drying and subsequent low temperature sintering is a promising way to fabricate ODS tungsten based alloys with high performance.
研究领域:
材料科学
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金属学与冶金工程
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纳米材料
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复合材料
·
结构材料
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DOI
高影响因子
DRYING TECHNOLOGY
·
2020
·
IF 2.988
Wei Wang,Shuo Zhang,Yanqiu Pan,Yujia Tang,Guohua Chen
To explore the effect of wave-absorbing material aided microwave heating on freeze-drying of initially porous frozen material, a lab-scale microwave freeze-dryer was designed with solid-state source selected as the microwave source instead of the traditionally used magnetron. Vitamin C was employed as the solute in aqueous solution. “Soft-ice” freezing technique was adopted to prepare solid and porous frozen materials. Experimental results showed that the solid sample by soft-ice freezing can successfully avoid structural collapse during freeze-drying, and the porous frozen material can significantly intensify mass transfer of the freeze-drying process. Under the operating conditions of 35 °C and 20 Pa, the drying time of the porous sample with the initial saturation of 0.25 decreased by 30.4% compared with the solid one, and the residual moisture content of dried product decreased with the initial saturation reducing. SEM images of the dried products revealed that the porous material had a loose pore structure and a tenuous solid skeleton, which is favorable to the migration of sublimated/desorbed vapor and the desorption of bound moisture. Evidences also showed that appropriately increasing radiation temperature led to reducing the drying time, while changing chamber pressure had an insignificant effect on freeze-drying. With sintered silicon carbide (SiC), which is a kind of wave-absorbing material, as the supporting pad of sample, microwave heating can greatly improve heat transfer of the freeze-drying process. Under the same operating conditions, the drying time of the porous sample with the microwave input power of 5 W was 28.1% shorter than that of the same sample without microwave heating, and 50.0% shorter than that of the solid sample for conventional freeze-drying. Wave-absorbing material aided microwave freeze-drying of the porous material frozen with preformed pores is a feasible and effective way to achieve the simultaneous intensification of heat and mass transfer in freeze-drying.
研究领域:
食品科学与工程
·
化学工程
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DOI
高影响因子
BIORESOURCE TECHNOLOGY
·
2026
·
IF 8.2
Shuo Zhang,Qi Fan,Wei Sun,Yanqiu Pan,Wei Wang
A wood-derived cellulose aerogel prepared by optimized freeze-drying (FD) • CS and PEI physically crosslinked with cellulose to enhance adsorption capacity. • The optimized FD reduced drying time and enhanced mechanical property of aerogel. • The prepared aerogel had high adsorption abilities for microplastics (PM) and dyes. • The aerogel showed excellent performance in recyclability and for PM plus dyes system. A wood-derived aerogel with charged functional groups and unidirectional pores was prepared for microplastics and dyes adsorption. The unidirectional freezing combined with the SiC-assisted microwave heating was employed to achieve the optimization of freeze-drying (FD). The results demonstrated that the optimized FD strategy could save the drying time by more than 43%. Meanwhile, this strategy imparted ordered pores in the aerogel, thereby improving the mechanical property. The prepared aerogel showed robust performance across a broad range of pH values and had high maximum adsorption capacities of 558.37, 433.13, and 863.35 mg·g −1 for microplastics, methylene blue, and Congo red, respectively. Moreover, the aerogel exhibited notable recyclability over 10 cycles, and had the ability to simultaneously remove PM plus dyes in binary pollutant systems. The research results provide a promising pathway for the sustainable utilization of forestry resource in the treatment of wastewater contaminated with microplastics and dyes. Download: Download high-res image (233KB) Download: Download full-size image
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
·
2026
·
IF 16.8
Ying Zhang,Jiaofan Sun,Dong Zou,Yiqing Zeng,Zhaoxiang Zhong,Weihong Xing
A modified freeze-drying strategy for asymmetric SiC ceramic membranes was proposed. • The membrane realized synergistic balance of high permeance, strength and filtration precision. • Key parameters precisely regulated the microstructure and comprehensive performance of the membrane. • The membrane showed ultra-high filtration efficiency for PM 0.3 and coal-fired fly ash at 300 °C. Unidirectional freeze-drying technique can boost the gas permeance of the ceramic membranes for gas filtration. However, the conventional unidirectional freeze-drying technique typically generates a highly uniform structure, which compromises the green body quality and the mechanical strength of the final ceramic membranes. Accordingly, this work proposed a modified unidirectional freeze-drying technique to fabricate asymmetric silicon carbide membranes (ASCM) by introducing a cross-linking and sedimentation pretreatment step prior to freezing. The ASCM membranes featured a distinct asymmetric gradient structure, with a dense fine-pore layer at the bottom and a lamellar porous structure at the top. Porosity exhibited a gradually increasing gradient from the bottom to the top surface. It was demonstrated that by adjusting cross-linking and sedimentation time, freezing temperature, and solid content, the ASCM membranes exhibited a tunable pore size distribution of 2.2–11.8 μm, porosity of 62.3%–72.1%, gas permeance of 113.9–595.9 m 3 m −2 h −1 kPa −1 and bending strength of 2.0–9.3 MPa. Additionally, the ASCM membranes exhibited outstanding high-temperature filtration performance for both standard PM 0.3 and real coal-fired fly ash, with a removal efficiency higher than 99.99%. This work provides a novel and feasible route for high-performance SiC ceramic membranes, enabling their engineering application in high-temperature gas-solid filtration. Download: Download high-res image (387KB) Download: Download full-size image
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DOI
高影响因子
DRYING TECHNOLOGY
·
2025
·
IF 2.7
Runze Lin,Shuo Zhang,Qi Fan,Yanqiu Pan,Wei Wang,Zhandong Wang
A starch-based aerogel was prepared through freeze-drying for solar interfacial evaporation (SIE). Attapulgite was used as the framework, and polydopamine-modified carbon black was used as the photothermal material. The freeze-drying process was enhanced using directional freezing to improve mass transfer and lossy material-aided microwave heating to improve heat transfer. Meanwhile, a multiphase transport model coupling mass and heat transfer equations with Maxwell’s equation was formulated and numerically solved. The enhanced freeze-drying achieved a 55.6% reduction in drying time compared with conventional freeze-drying. The simulation results showed excellent agreements between numerical and experimental drying curves. The SIE results displayed that the prepared aerogel had 1.93 kg·m−2·h−1 of evaporation rate and 94.1% of light-evaporation conversion efficiency for pure water. The aerogel maintained 96.7% of initial evaporation rate for 3.5% modeled brine after 20 cycles. This work is expected to provide a sustainable and economical approach to the desalination.
研究领域:
材料科学
·
环境科学
·
能源科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2019
·
IF 5.155
Jinlong Hu,Wenxin He,Shudi Qiu,Weijian Xu,Yaohua Mai,Fei Guo
Functionalized carbon electrodes with hierarchical porous structure play an essential role in the fabrication of high-performance supercapacitors . Here, we report a novel freeze-drying assisted carbonization approach for the preparation of nitrogen-doped hierarchically porous carbons (NHPCs). Using urea as both the pore-forming agent and the nitrogen source, and sodium alginate (SA) as the carbon precursor, we are able to modulate the porosity and N-doping concentration of the NHPCs by simply altering the carbonization temperature and the dosage of urea. The prepared NHPCs exhibit specific surface area as high as 1179 m 2 g −1 with 70% micropore and high N- and O-doping concentration of 6.7 wt% and 13.8 wt%, respectively. Carbon electrodes based on these NHPCs show a high gravimetric capacitance (305 F g −1 at 1 A g −1 ) and an excellent rate ability (retaining 73.8% at 20 A g −1 ) in three-electrode systems. The NHPCs symmetric supercapacitor delivers excellent energy density of up to 23.8 W h kg −1 as well as long-term electrochemical stability (95.8% capacitance retention over 10, 000 cycles). The abundance of the raw materials combined with the simple fabrication procedure makes the SA-derived NHPCs as promising electrode materials for the next generation advanced supercapacitors .
研究领域:
材料科学
·
能源存储技术
✓ 已验证
DOI
高影响因子
CELLULOSE
·
2019
·Vol. 26
·期 11
·6653-6667
·
IF 3.917
Chen Yiming,Zhou Lijie,Chen Lian,Duan Gaigai,Mei Changtong,Huang Chaobo,Han Jingquan,Jiang Shaohua
Abstract Directional freeze-drying is considered to regulate the structure of nanocellulose aerogels with special performances. In this work, TEMPO-oxidized cellulose nanofiber aerogels with high porosity (> 99.5%) and low density (~ 7 mg/cm 3 ) were produced by different freeze-drying methods. The effects of temperature, freezing reagents and freezing methods on the structure and properties of aerogels were investigated. Among them, an anisotropic cellulose aerogel was obtained using a simple and flexible directional freezing in ethanol of − 30 °C by a self-made directional freezer. Our results demonstrated that it could present honeycomb-like pores in the transverse direction and regular directional tunnels in the longitudinal direction, and some attractive features, such as high water adsorption (120 g/g) and stability in water. Compared with other aerogels, this anisotropic structure also provided the aerogel with excellent compressive property (15.2 kPa) and faster liquid transport (4.95 mm/s) in the longitudinal direction than in other directions. The distinctive aerogels based on nanocellulose by directional freeze-drying are also expected to be combined with multifunctional materials to achieve directional applications to meet the requirements of different fields. Graphic abstract
研究领域:
材料科学
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
LWT-FOOD SCIENCE AND TECHNOLOGY
·
2022
·
IF 6.056
Dan Hu,Jinyong Wu,Jun Li,Long Jin,Xiangsong Chen,Jianming Yao
Improvement in the survival of the edible probiotic Pediococcus pentosaceus during the preparation and storage is important. In this study, the protective effects of isomaltose oligosaccharide in a protective agent (sodium glutamate, skimmed milk, and trehalose) on P. pentosaceus during vacuum freeze-drying and low-temperature storage were evaluated. Cell damage, and texture were evaluated using fluorescence analyses, and scanning electron microscopy, respectively, and a water activity assay was performed storage after 1 month of storage (−80, −20, 4, 25 °C). The viability of P. pentosaceus agents (24444, QK-1, MQ-1, and RQ-1) were evaluated for 9 months storage. The results showed that IMO increased 11.02% survival rate of P. pentosaceus QK-1 during the freeze-drying process, which was better than that of 24444, MQ-1, and RQ-1; the texture of the protective agent was thin, with a compact and granular cross-section. Decreased water activity (18.71–34.26%) and cell damage (8.32–10.53%), also enhanced survival rate (5.98–12.85%) were observed in the IMO-containing groups in storage. The survival rates of P. pentosaceus (QK-1, MQ-1, RQ-1) direct-injection agents (9 months) exceeded 90% under gastrointestinal satiety-mimicking conditions in vitro . Our data indicate that IMO has a good protective effect on the freeze-drying and storage processes of P. pentosaceus .
研究领域:
食品科学
·
微生物学
·
生物技术
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2023
·
IF 6.2
Ming Li,Xi Chen,Jinjin He,Shucheng Liu,Yi Tang,Xiaogang Wen
Hierarchical NiCo-LDH microspheres (NiCo-LDHM) were synthesized via a simple one-step hydrothermal process in the presence of 2-methylimidazole, and a freeze-drying technique was subsequently used to further adjust its microstructure. The obtained porous hierarchical microspheres are about 5 µm in average diameter, and consist of ultrathin nanosheets with an average thickness of 5 nm. The freeze-drying endows LDH microspheres with higher surface area and improved pore structure . The unique hierarchical porous structure, high specific surface area and positive surface charge together contribute NiCo-LDHM’ excellent capability for anionic dyes and heavy metal ions removal, its theoretical adsorption capacities for Congo red (CR), acid fuchsin (AF) and Cr(VI) are 2120, 1176 and 123 mg/g at room temperature respectively. The adsorption of pollutant molecules/ions onto NiCo-LDH microspheres conforms to the quasi-secondary kinetics model. Isotherm studies suggest that the CR adsorption onto adsorbent fits Langmiur model, while AF/Cr(VI) adsorption fits Freundlich model, indicating that the size and morphology of pollutant molecules influence the adsorption process . The adsorption is a spontaneous endothermic process and NiCo-LDHM demonstrates good recyclability, the removal rates of CR, AF and Cr(VI) can still reach 90.7%, 84.7% and 82% after five cycles, respectively. In addition, NiCo-LDH hierarchical microspheres also exhibit good anionic selective adsorption capacity in mixed-dye systems, displaying great potential for water restoration and dye recycling.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2026
·Vol. 109
·期 5
·e70780
·
IF 4.2
Yu Ma,Huangshuai Zhang,Zhenting Zhu,Zihao Yang,Jinglong Zhang,Xiaoyu Wu,Hang Zhang
Alumina aerogels are attractive for thermal insulation due to their ultralow thermal conductivity and excellent high-temperature resistance, but the high cost of organic aluminum alkoxide precursors limits large-scale use. Inorganic aluminum salts are low cost and stable but unsuitable for conventional supercritical or ambient pressure drying. Herein, aluminum chloride hexahydrate (AlCl 3 ·6H 2 O) with tert-butanol/water cosolvent was employed to prepare alumina aerogels via vacuum freeze-drying. The freeze-dried aerogels were crack-free with tunable properties. Increasing precursor concentration enhanced specific surface area (SSA) and mechanical strength, though with higher density and thermal conductivity. The minimum density and thermal conductivity are 0.066 g/cm 3 and 0.028 W/(m·K), whereas the maximum SSA and Young's modulus are 364.74 m 2 /g and 343.07 kPa. The aerogels maintained thermal conductivity below 0.190 W/(m·K) up to 1200°C, but at 1400°C phase transformation to α-Al 2 O 3 caused severe skeleton coarsening and degraded thermal insulation. This study provides a potentially cost-effective and efficient fabrication route for monolithic alumina aerogels.
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DOI
高影响因子
危险品化学品经营许可证（带存储）