CHEMICAL ENGINEERING JOURNAL
·
2021
·
IF 13.273
Ben Wu,Xue Jiang,Shuning Yu,Peng Bai,Xianghai Guo,Jiafei Lyu
A growing demand of boric acid has been forecasted with the rapid development of industries while the world is suffering the consequence from boron-containing wastewater. Metal–organic frameworks (MOFs) with exceptional stability and remarkable surface area have been preliminarily identified as effective boron adsorbents, adsorption mechanism has yet been elucidated though. Herein Zr 6 /Hf 6 -based NU-1008 and NU-903 were studied for boron removal from water for the first time where around 4.82, 6.27, 3.49 and 6.34 boron were captured per Zr 6 /Hf 6 cluster for Zr-NU-1008, Hf-NU-1008, Zr-NU-903 and Hf-NU-903 through a spontaneous endothermic process with fast kinetics by means of chemisorption. Larger capacity of Hf 6 -based MOFs than Zr 6 -based MOFs can be explained by the weaker electronegativity of hafnium than zirconium. The increased binding energy of Zr 3d, Hf 4f and O 1s as well as reduced binding energy of B 1s suggested the interaction between electron-deficient boron and the hexanuclear clusters (M 6 ). Owing to the crystalline nature of NU-1008, the boron binding sites were precisely elucidated by single crystal X-ray diffraction where boric acid was attached to the available coordinative sites on the M 6 clusters through the M 6 -O-B(OH) 2 connection.
研究领域:
环境科学
·
材料科学
·
化学
✓ 已验证
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2023
·
IF 4.2
Ziqi Ren,Lu Fang,Miao Cui,Tianming Lv,Huifang Wu,Ziyi Feng,Zhaochi Feng,Changgong Meng,Limin Ren
Catalyst engineering plays a key role in bridging gaps between the structure of the Lewis acid center and its corresponding catalytic performance. In this regard, work that has been done in tuning active sites of Hf-containing zeolites, which hold promising catalytic activity for a variety of hydrogen-shift reactions, is far from complete. Herein, a Hf-B-BEA catalyst was rapidly prepared (within hours) by a hydrothermal semi-reconstruction strategy, involving partial framework etching of parent B-BEA and Hf grafting during the reassembling process. Then, an acid treatment was performed for expelling the boron atoms from the framework; more importantly, Hf migration into the silanol nests was triggered. The acid treatment worked powerfully as the driving force for transforming the semi-framework Hf into well-defined tetrahedrally coordinated framework Hf, thus endowing Lewis acidity of the obtained Hf-BEA. Consequently, this operation greatly boosted the Meerwein–Ponndorf–Verley reduction performance of Hf-BEA, which was almost inactive over the pristine Hf-B-BEA. The rational regulation of Hf sites provides new concepts in designing Hf-containing zeolites and understanding the structural–activity relationship.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2025
·
IF 5.6
Huan Guo,Bingzhu Wang,Ruifeng Li,Hongrui Wang,Jixiang Dai,Yong She,Yongzhong Zhao,Jianjun Sha
In order to elucidate the synergistic mechanism of boride and carbide phase in ultrahigh-temperature ceramics (UHTCs) under ablation condition, in this work, the ablation behaviour of (Hf, Ta)B 2 -(Hf, Ta)C-SiC ceramics with different (Hf, Ta)B 2 to (Hf, Ta)C molar ratios was systematically investigated by oxygen-acetylene test under a heat flux of 3.2 MW/m 2 . It was found that the oxides generated from (Hf, Ta)B 2 and (Hf, Ta)C enhanced the matching capacity of oxides with different melting points, being formed a dense ablation layer. When the molar ratio of (Hf, Ta)B 2 to (Hf, Ta)C was 2:1, the ceramic achieved a near-zero ablation rate (0.042 μm/s), which was 1.62 times lower than that of (Hf, Ta)C-SiC ceramics. The mechanism for the enhanced ablation resistance was attributed to the Hf 6 Ta 2 O 17 generated during the ablation reaction, which reduced the viscosity of the ablation products and infiltrated into the pores of ceramics. The formation of such ablation layer could inhibit the impregnation of oxygen and the depletion of easily volatile oxides, including SiO 2 and B 2 O 3 , being formed a multi-element composite ablation layer with self-healing ability, which was helpful for the protection of the substrate from continuous oxidation damage.
研究领域:
材料科学
·
陶瓷与复合材料
·
高温材料
·
烧蚀物理
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2020
·
IF 3.83
Ke Chen,Youhu Chen,Jianning Zhang,Yujie Song,Xiaobing Zhou,Mian Li,Xiaomeng Fan,Jie Zhou,Qing Huang
Medium- and high-entropy alloys or ceramics for tuning the physicochemical properties of materials by the combination of multiple principal elements have received much interest. Herein, a medium-entropy (Ti, Zr, Hf) 2 SC phase was synthesized attributing to the structural and chemical diversity of MAX phases. The crystal structure of (Ti, Zr, Hf) 2 SC was determined by the Rietveld refinement of XRD , SEM, and atom-resolved TEM along with EDS elemental analysis . Phase evolution of X-ray diffraction patterns and TG/DSC curves were employed to reveal the synthesis mechanism of (Ti, Zr, Hf) 2 SC from 2TiC–Zr–ZrC-2HfH 2 -3.2FeS reactant system. The Vicker's hardness and the electrical resistivity of (Ti, Zr, Hf) 2 SC were found higher than those of Ti 2 SC, but the thermal conductivity of (Ti, Zr, Hf) 2 SC was lower.
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY
·
2020
·Vol. 35
·期 5
·953-960
·
IF 3.498
Wen-Gang Liu,Shuang Wei,Jian Zhang,Cong Ao,Fu-Tian Liu,Bin Cai,Hong-Ying Zhou,Ji-Long Yang,Chao-Feng Li
A cation-exchange resin is commonly used to separate Sr from geological and environmental samples. AG50 resin is the most traditional cation-exchange resin and has the advantages of good reusability and low cost. Although AG50 resin can meet the demands of most conventional geological samples, eliminating 87Rb isobaric interference from samples with high Rb/Sr ratios (>30) is difficult during one-step separation. Separating Sr twice using AG50 resin is the general approach to Rb removal. The two-step separation method is time consuming and leads to a low Sr yield. This study aimed to improve the sample throughput and overcome the problem of 87Rb isobaric interference from imperfect separation. A new separation method involving hydrofluoric acid (HF acid) coprecipitation combined with a cation-exchange resin (i.e. AG50 resin) for samples with high Rb/Sr ratios was developed. HF acid was used as a coprecipitator to remove most Rb (>90%) and recover Sr before performing AG50 column chemistry. The reliability of this method was examined using the rhyolite standard JR-2, a typical sample with a high Rb/Sr ratio (Rb/Sr = 37.36). Results in the JR-2 case showed that approximately 92% of Rb and most of the matrix elements (K, Ti, Fe, Al, Mn and Na) could be removed effectively. Moreover, Sr recovery exceeded 91% during HF acid coprecipitation. After the removal of Rb by HF acid coprecipitation, the Sr fraction with high purity was easily obtained through one-step separation using the AG50 resin column. However, we found that the removal rates of Rb and some matrix elements (such as Al and Na) were strongly affected by the composition of Al–Ca–Mg in samples. Our separation method is more suitable for samples with high Rb/Sr ratios and low Ca and Mg contents. A series of silicate rock reference materials were selected to evaluate the applicability of our method, and the Sr isotopic results were consistent with previously reported values. Overall, this rapid, simple and low-cost method shows great potential for the separation of Sr from geological samples with high Rb/Sr ratios, such as alkaline feldspar granite, alkaline granite and alkaline rhyolite.
研究领域:
地质学
·
地球化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
·
2025
·
IF 14.3
Junjie Xu,Wei Sun,Xiang Xiong,Yi Zeng,Qingbo Wen
Conventional ultra-high-temperature ceramic-modified carbon/carbon composites (C/C-UHTCs) face limitations such as excessive erosion in the gas environment of solid rocket motors (SRMs). In contrast, metal-reinforced C/C-UHTCs exhibit enhanced mechanical properties, thermophysical characteristics, and resistance to high-temperature erosion. These advantages indicate significant potential for metal-reinforced C/C-UHTCs to augment the thrust capabilities of SRMs. This study demonstrated the preparation of (Hf, Zr, Ti)C-(Hf, Zr, Ti)B 2 -W-Cu cermet modified C/C composites using slurry infiltration and reactive melt infiltration at 1400°C. The microstructure, formation mechanisms, mechanical properties, and thermophysical properties of C/C-(Hf, Zr, Ti)C-(Hf, Zr, Ti)B 2 -W-Cu composite materials, as well as the ablation behavior of the composite materials under the SRM environment were compared. The results showed that the linear and mass ablation rates of the C/C-(Hf, Zr, Ti)C-(Hf, Zr, Ti)B 2 -W-Cu composite material decreased by 112.1% and 160.4% (0.074 mm s −1 , 0.086 g s −1 ), respectively, compared with those of the C/C-(Hf, Zr, Ti)C composite material. This could be attributed to the formation of a dense, high-strength W-skeleton composite (Hf, Zr, Ti)O 2 oxide layer during the ablation of the C/C-(Hf, Zr, Ti)C-(Hf, Zr, Ti)B 2 -W-Cu composite, which effectively resisted erosion from high-temperature, high-speed and high-particle-concentration two-phase gas flow. This work presents a novel approach to enhancing the ablation resistance of C/C-UHTCs and holds significant promise for the development of structural materials in SRM environments.
✓ 已验证
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2025
·
IF 6.2
Huan Guo,Bingzhu Wang,Ruifeng Li,Xiaohu Li,Jixiang Dai,Yongzhong Zhao,Jianjun Sha
Aiming at the high sintering temperature and densification difficulty in ultrahigh-temperature ceramics, the low-temperature facial and fast preparation of ultrahigh-temperature multi-phases (Hf, Ta)B 2 -(Hf, Ta)C-SiC solid solution ceramics was realized using in-situ reaction combined with hot pressing, where the HfSi 2 , TaSi 2 , B 4 C and C were used as raw materials. The effect of Hf/Ta molar ratio on the microstructural evolution and mechanical properties of ultrahigh-temperature multi-phases ceramics was investigated. The results found that the in-situ reaction and the formation of solid solution phase could promote the densification process. On the other hand, the addition of Ta element induced the formation of high aspect ratio grains with an interlock structure within the ceramic matrix and significantly improved the mechanical properties. When the Hf/Ta molar ratio was 7/3, the multi-phases ceramics exhibited the best mechanical properties, with a hardness of 25.59 GPa, a flexural strength of 556.61 MPa, and a fracture toughness of 5.13 MPa·m 1/2 . The enhanced mechanical properties were attributed to the synergistic effect of multiple strengthening and toughening mechanism, including grain bridging, crack bifurcation and grain pullout induced by high aspect ratio (Hf, Ta)B 2 grains.
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
·
2021
·Vol. 47
·期 24
·34568-34574
·
IF 4.527
Wenlong Huang,Ying Li,Haiqiang Lu,Yushi Ding,Yandong Liu
Doped CaZrO 3 proton conductors are promising materials for electrochemical hydrogen sensors, which have already been used in commercialized hydrogen sensors for aluminum melts. Hafnium and Zirconium possess similar properties but their influences on conductive properties of CaZrO 3 proton conductors have not been well investigated. In this study, CaZr 0.9 Sc 0.1 O 2.95 and CaHf 0.9 Sc 0.1 O 2.95 were prepared by solid-state reaction, and their conductivities and transport properties were systematically investigated by defect equilibria model. Total conductivities of CaZr 0.9 Sc 0.1 O 2.95 and CaHf 0.9 Sc 0.1 O 2.95 reached 4.70 × 10 −5 −1.69 × 10 −3 S·cm −1 and 4.83 × 10 −6 −9.71 × 10 −4 S·cm −1 under humid air and 400 °C−800 °C. Their total standard molar hydration enthalpies were estimated to −59.1 kJ/mol and −56.9 kJ/mol, respectively. Conductivities of grain interiors were higher than those of total conductivities, and activation energies of protons were lower than oxide vacancies and holes. Transport numbers showed protonic conduction of Ca(Zr/Hf) 0.9 Sc 0.1 O 2.95 to always dominate under humid air at 400 °C−700 °C. Protonic transport numbers of CaZr 0.9 Sc 0.1 O 2.95 and CaHf 0.9 Sc 0.1 O 2.95 were estimated to 0.41 and 0.44 at 800 °C, respectively. Meanwhile, protonic transport number of grain interiors was higher than that of total sample. Therefore, grain interior could block the transfer of oxide vacancies and holes. In sum, these findings look promising for application on electrochemical hydrogen sensors.
研究领域:
材料科学
·
电化学
·
固体离子学
·
传感器技术
✓ 已验证
DOI
高影响因子
COMBUSTION AND FLAME
·
2025
·
IF 6.2
Xiandie Zhang,Haozhe Li,Xuxu Cui,Xinwen Ma,Jiaming Liu,Xiaode Guo,Xiang Zhou
The passivation layer of Al powder hinders the mass transfer during Al combustion. Fluorinated oxidants, such as metal fluorides and fluoropolymers, substantially improve the combustion behaviour of Al powder. Herein, a simple solvothermal method is employed to produce a high-entropy acicular accumulational fluorine-containing oxidiser based on ammonium fluoroferrates. The characterization results indicate that heating the fluorine-containing oxidiser can release gaseous products of HF and NH 3 . HF etches the passivation layer, and NH 3 provides kinetic energy to the fuel, resulting in multiple hot spots and secondary combustion as well as prevention of reaction sintering. Compared with traditional FeF 3 , this novel fluorine-containing oxidiser considerably improves the combustion of Al powder by reducing its onset temperature as well as increasing its exothermic enthalpy, flame area and F release ability.
研究领域:
材料科学
·
燃烧化学
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2023
·
IF 8.2
Yinglan Li,Jie Xu,Qingran Guan,Huaizhen Zhang,Zhuang Ding,Qingpeng Wang,Zhengping Wang,Jun Han,Min Liu,Yanna Zhao
Solid dispersions (SDs) possess the potential to enhance the bioavailability of insoluble active pharmaceutical ingredients (APIs) by effectively converting them into amorphous state. However, SDs have a tendency to recrystallize unless appropriate excipients are employed. The objective of this study was to evaluate the ability of hypromellose acetate succinate HF (HPMCAS-HF) and Soluplus® to inhibit the recrystallization of β-carotene and improve its in vivo bioavailability through the fabrication of ternary β-carotene solid dispersions (SDs) with the aid of specific surfactant. Due to rapid micellization , the dissolution profiles of β-carotene SDs based on HPMCAS-HF/Span 20 (5:5, w/w) or Soluplus®/Span 20 (6:4, w/w) combinations exhibited significant improvement, which were almost 7–10 times higher than β-carotene bulk powder. DSC and PXRD analysis indicated a notable reduction in the crystallinity degree of β-carotene within the SDs. The stability study demonstrated a half-life of β-carotene in the SDs exceeding 30 days. Additionally, the in vivo pharmacokinetics analysis confirmed that the cellulose derivatives/surfactant combinations significantly enhanced the bioavailability of β-carotene by 1.37-fold and 2.3-fold, respectively. Notably, the HPMCAS-HF/Span 20 combination exhibited superior performance. Consequently, the HPMCAS-HF/Span 20 combination held potential for the advancement of an effective drug delivery system for β-carotene.
研究领域:
药剂学
·
生物医学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Journal of Materials Research and Technology-JMR&T
·
2024
·
IF 6.2
Xinyu Ping,Bin Meng,Weixin Zeng,Ziran Chai,Zhengteng Wang,Xiaoyu Pan
Three new rare-earth high-entropy oxides with compositions of (Y 1/7 La 1/7 Nd 1/7 Sm 1/7 Gd 1/7 Yb 1/7 Lu 1/7 ) 2 O 3 (7HEO), (Y 1/8 La 1/8 Nd 1/8 Sm 1/8 Gd 1/8 Yb 1/8 Lu 1/8 Ce 1/8 ) 2 O 3 (8HEO) and (Y 1/10 La 1/10 Nd 1/10 Sm 1/10 Gd 1/10 Yb 1/10 Lu 1/10 Ce 1/10 Zr 1/10 Hf 1/10 ) 2 O 3 (10HEO) were prepared using a solid-state reaction method combined with conventional sintering at 1600 ° C for 10 h 7HEO has a monoclinic structure. The addition of Ce into 7HEO not only leads to the phase transformation from monoclinic to bixbyite structure, but also contributes to the grain refinement. When the three elements of Ce, Zr and Hf are added into 7HEO, a second fluorite-structured phase forms and further promotes the grain refinement. 10HEO and 8HEO have a higher thermal conductivity compared with 7HEO in 25–600 °C. When the temperature reaches 900 ° C, the thermal conductivity of 8HEO is lower than that of 7HEO. The addition of Ce or Ce/Zr/Hf into 7HEO causes the weakening of the bond strength and the increase of the bond length of cation-O 2- in the samples, which in turn increases the thermal expansion coefficient. Moreover, 7HEO possesses a better oxygen barrier property compared with 8HEO and 10HEO. The hardness and Young's modulus of 7HEO are lower than those of 8HEO and 10HEO.
研究领域:
材料科学
·
无机化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2025
·
IF 6.3
Huan Guo,Bingzhu Wang,Ruifeng Li,Cheng Su,Jixiang Dai,Yong She,Yongzhong Zhao,Jianjun Sha
Low-temperature sintering and phase/microstructure tailoring of multi-element ultra-high temperature ceramics remain challenging, restricting the improvement of mechanical properties and the development of ultra-high temperature ceramic materials. In this work, a novel low-temperature reactive sintering technology was used to tailor the content of multiple borides and carbides in (Hf, Ta)B 2 -(Hf, Ta)C-SiC ceramics. It was found that the introduction of borides promoted the densification process of multi-phase ceramics. With the increase of borides content, the grain size of multi-phase ceramics gradually increased. The introduction of moderate amount borides helped to form a uniformly refined microstructure. When the molar ratio of borides to carbides was 2:1, the flexural strength and fracture toughness of multi-phase ceramics were the highest, which were 487.57 ± 38.3 MPa and 5.04 ± 0.09 MPa·m 1/2 , respectively. The main strengthening and toughening mechanisms included pullout of (Hf, Ta)B 2 grains and crack deflection.
研究领域:
材料科学
·
陶瓷
·
机械工程
·
固态物理学
✓ 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）