CARBON
·
2026
·
IF 12.7
Huan Guo,Wenhao Dou,Ruifeng Li,Bingzhu Wang,Yonghui Yu,Yong She,Yongzhong Zhao,Jianjun Sha
It is crucial to address the challenges for low-temperature densification and interfacial reactions during the fabrication of multi-element ultra-high temperature ceramic matrix composites. In this paper, C sf /(Hf, Ta)B 2 -(Hf, Ta)C-SiC composites were prepared via reactive hot-press sintering at low temperatures. The intrinsic connection between the fiber content, microstructure, and mechanical behavior of the composites was elucidated. The results indicated that the ultrasonic dispersion combining with fast hot-press sintering effectively promoted the uniform dispersion of C sf in the matrix and achieved densification at 1700 °C. The composites exhibited an undamaged fiber-matrix interface without observable interfacial phase, demonstrating that low-temperature preparation effectively prevented fiber degradation from interfacial reactions. Compared to the unreinforced ceramics, the composites showed decreased flexural strength and fracture toughness, yet possessed higher work of fracture and larger critical crack size. This indicated that fiber addition improved the damage tolerance and structural reliability by inhibiting the catastrophic brittle fracture behavior inherent to monolithic ceramics. The composite with 20 vol% C sf offered the best balance of strength, toughness and non-catastrophic failure behavior. The flexural strength and fracture toughness were 260.6 MPa and 4.82 MPa m 1/2 , respectively. Download: Download high-res image (531KB) Download: Download full-size image
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DOI
高影响因子
CORROSION SCIENCE
·
2021
·
IF 7.205
Mingde Tong,Qiangang Fu,Mingyu Liang,Tao Feng,Wanbo Hou,Jia Sun,Xinhao Shi
To optimize the impact-ablation resistance of SiC nws @PyC/HfC coating, PyC-SiC double-layer interface phase was introduced. After impacting test, the crack widths of SiC nws @PyC-SiC/HfC were much lower than that of SiC nws @PyC/HfC coating. The impact-ablation resistance of SiC nws @PyC-SiC/HfC coating was better than that of SiC nws @PyC/HfC coating. The good impact-ablation resistance SiC nws @PyC-SiC/HfC coating attributed to the two-grade pull-out reinforcement effect, self-sealing function of Hf-Si-O glass generated from oxidation of SiC nws @PyC-SiC core-shell structure and the precipitation of HfO 2 grains from Hf-Si-O glass under ablation environment.
研究领域:
材料科学
·
航空航天工程
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DOI
高影响因子
CATALYSIS LETTERS
·
2023
·
IF 2.8
Xu Lingling,Pan Xiaomei,Wu Ningxin,Gao Lijing,Xiao Guomin
The conversion of biomass energy sources is a crucial direction in the transformation of energy resources, such as cellulose to high-value chemicals. As an important platform compound, 5-hydroxymethylfurfural (HMF) is one of the worthwhile products from biomass. Previously, the use of Hf/ZSM-5 catalyst demonstrated excellent catalytic performance, with the yield of HMF reaching 67.50% under optimal reaction conditions (120 min, 190 °C, H 2 O(NaCl)/THF). Based on the previous work, the effect of a series of metal salts on the preparation of HMF from cellulose catalyzed by Hf/ZSM-5 catalyst was investigated in this paper. This result demonstrates the addition of AlCl 3 promoted the production of HMF yield and AlCl 3 completed with excellent performance among five metal salts. Moreover, the yield of HMF was improved to 70.95% by adjusting the optimal reaction conditions. Graphical Abstract
研究领域:
化学工程
·
能源科学
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产品关联
DOI
高影响因子
MICROELECTRONIC ENGINEERING
·
2024
·
IF 2.6
Wenwu Li,Caifang Gao,Xifeng Li,Jiayan Yang,Jianhua Zhang,Junhao Chu
Device stability is one of the key parameters for transistor applications. To improve the stability of Indium oxide (In 2 O 3 ) after a long-time gate bias, a synthetic solution of hafnium chloride (HfCl 4 ) and indium nitrate (In(NO 3 ) 3 ∙xH 2 O) reagents were used to obtain 0% to 5-at.% Hf doped In 2 O 3 thin-film transistors. With the increase of Hf doping concentration, oxygen vacancies and residual hydroxyl groups continue to decrease, suppressing the carrier concentration and influencing the trap state density of In 2 O 3 . The sub-threshold slope (SS) 0.78 V·dec −1 for the undoped In 2 O 3 transistor in this work is a typical value. When the dopant dose is up to 5-at.%, SS decreases to 0.32 V·dec −1 . According to the proportional relationship between SS and the density of trap states, it shows that the density of trap states in the dielectric layer and the semiconductor/dielectric interface SS is greatly reduced after 5-at.% Hf doping. The probability of the charge being trapped is dropped as well. At the same time, under the doping of Hf, the transistor exhibits a very small threshold voltage shift. Especially at the dopant dose of 5-at.%, the transfer characteristic curve hardly shifts. This work demonstrates an In 2 O 3 transistor with high bias stability by doping method.
研究领域:
材料科学
·
电子工程
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产品关联
DOI
高影响因子
PHYSICA SCRIPTA
·
2024
·Vol. 99
·期 8
·085914
·
IF 2.6
Yajun Xu,Qichen Zhao,Jianian Chen,Jingzhe Zhang,Binbin Xu
In recent years, graphene oxide assisted etching silicon has been considered a potential method to replace metal-assisted chemical etching. This work demonstrated the catalytic ability of graphene oxide synthesized by the Hummers method to promote chemical etching of silicon. By adjusting HF/H2O2 ratio of the solution and reaction temperature, a minimum weighted average reflectance of 9.9% in the wavelength range of 300–1100 nm was obtained. An etching rate of 10 μm h−1, faster than those in others' reports, was obtained in an optimized acidic solution at 80 °C. Finally, a four-electron model for graphene oxide assisted etching mechanism was proposed to explain our research results.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE
·
2025
·
IF 2
Jiao Hua,Wang Qingxiang,Wang Jia,Zhao Kang
HfC and TiC are high-temperature materials which can be used in astronautic and aeronautic industries. The titanium (Ti) and zirconium (Hf) have the similar chemical properties due to they are in the same IVB family. Zr x Hf 1-x C composites doped with different Hf contents are prepared by pyrolysis of ZrC precursors. The precursor of aqueous solution systems is more environmentally friendly than in organic systems. The results show that prepare high-purity Zr x Hf 1-x C composites can be obtained at the Zr: C and Hf: C molar ratio more than 1: 4. The mole number of C is at least four times than the metal ions Zr 4+ or Hf 4+ . All the prepared composites exist in the form of solid solution. The results show that the average particle size of Zr x Hf 1-x C composite ceramic particles is about 100 nm, and the distribution is uniform and dendritic. Zr 0.25 Hf 0.75 C composites can increase the oxidation temperature to 478.6 °C, which is a certain increase compared with the initial oxidation temperature of ZrC of 460 °C. Meanwhile, the first principles simulation showed that Zr 0.5 Hf 0.5 C has the best mechanical property and thermodynamic properties in Zr x Hf 1-x C system, which can provide a future choice for good mechanical properties of block materials.
研究领域:
材料科学
·
陶瓷
·
高温材料
·
复合材料
·
固态化学
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DOI
高影响因子
HOLZFORSCHUNG
·
2022
·
IF 2.493
Li Yan,Xiaodi Ji,Feiyang Zeng,Zhangjing Chen,Yafang Lei
As a renewable biomass material, wood is often deteriorated by decay fungi. Quercetin was here grafted onto poplar ( Populus nigra ) using oxalic acid as a linker through vacuum-pressure treatment and esterification with various molar ratios of quercetin to oxalic acid (Q/O) to enhance the wood decay resistance. Decay resistance, flexural strength, graft mechanism, and microscopic structure of the quercetin-grafted wood were analyzed. Results indicated that the decay resistance of quercetin-grafted wood to white-rot fungi ( Trametes versicolor ) and brown-rot fungi ( Gloephyllum trabeum ) was significantly improved. The modulus of rupture (MOR) of the quercetin-grafted wood was reduced while the modulus of elasticity (MOE) was improved. Quercetin was grafted onto wood through formation of ester groups among oxalic acid, wood, and quercetin. The highest amount of ester groups in the grafted wood was achieved when Q/O was 1:2 and Q/O lower than 1:2 would severely degrade the wood. The thickness of cell walls of the quercetin-grafted wood increased and reached a maximum of 2.2 μm with Q/O of 1:2. Quercetin can be grafted on wood cell wall by oxalic acid as an environment-friendly preservative to enhance the decay resistance of wood.
研究领域:
林学
·
材料科学
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DOI
高影响因子
HOLZFORSCHUNG
·
2014
·Vol. 69
·期 3
·367-374
·
IF 2.339
Feng Liu,Zhengxin Gao,Deli Zang,Chengyu Wang,Jian Li
A three-step procedure has been developed for superhydrophobic coating on wood based on epoxy/silica materials in combination with hydrophobization. First, the epoxy resin is adhered to wood by immersing the samples into an epoxy resin acetone solution, then amino-functionalized silica particles are anchored by the epoxide groups, and finally, the created surface is modified by octadecyltrichlorosilane (OTS). The superhydrophobic surface not only is water repellent, as shown by the contact angle (CA) tests, but also decreases essentially the wood’s water absorption as determined by a 120-day water immersion test. The good mechanical stability of the coating was confirmed by a sand collision method.
研究领域:
材料科学
·
林业工程
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DOI
高影响因子
HOLZFORSCHUNG
·
2023
·Vol. 77
·期 6
·437-452
·
IF 2.4
Haonan Zhang,Qi Liu,Yanchen Zhu,Zhang Feng,Hao Ren,Huamin Zhai
In this study, representative lignin samples differing in hydroxyl content, molecular weight, linkage composition and lignin units ratio were prepared from eucalyptus wood by different isolation means and modification means: milled wood lignin (MWL), kraft lignin classified at different pH (KL), lignocresol (LC), lignoresorcinol (LR), lignopyrogallol (LP) as well as lignocresol secondary functional switched samples (LC 2 nd deriv). The structure of various lignins was characterized in detail by Fourier transform infrared (FT-IR) spectroscopy, gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR). In order to eliminate the interference of other factors, bovine serum albumin (BSA) with relatively simple protein structure and different kinds of lignin and their derivatives were selected as the research objects. The adsorption/desorption behavior and mechanism between lignin samples and BSA were studied by quartz crystal microbalance with dissipation monitoring (QCM-D). The results showed that the content of phenolic hydroxyl was the main factor affecting the interaction of lignin and BSA, but in addition, the molecular size, linkages composition and the types of lignin units also had important effects on its adsorption behavior. The research will provide theoretical guidance and all-round reliable basic data for the interaction of lignin on lignocellulose hydrolysis enzymes in industrial application.
研究领域:
生物化学
·
材料科学
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DOI
高影响因子
HOLZFORSCHUNG
·
2023
·Vol. 77
·期 7
·527-540
·
IF 2.4
Li Yan,Zeyao Yan,Jiang Chen,Zhangjing Chen,Yafang Lei
Vanillin is an antifungal and environmentally friendly compound. In this study, vanillin and silica microcapsules (VSM) were microencapsulated using the sol-gel method and then impregnated into wood. Scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDXA) and transmission electron microscopy (TEM) were used to characterize the morphological structure and distribution of VSM in wood. Fourier transform infrared spectroscopy (FTIR) was used to study the intermolecular interactions between VSM and wood. The antifungal performance of the VSM-treated wood was evaluated. The study revealed that VSM had good sustained-release performance and decay resistance. Mass losses of VSM-treated wood after leaching and exposure to Trametes versicolor (L.) Quel. and Gloephyllum trabeum (Pers.) Murrill decreased from mass losses of 20.8 % and 15.9 % of the control group to 9.2 % and 6.4 %, respectively. VSM treatment disrupted the mycelium of T. versicolor and G. trabeum , inhibited their respiratory metabolism, and the ligninase-laccase enzyme activity of T. versicolor . Meanwhile, MOR and MOE of VSM-treated wood were 96.7 MPa and 12.3 GPa which were 28.8 % and 11.5 % higher than the control group, respectively.
研究领域:
材料科学
·
生物学
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DOI
高影响因子
HOLZFORSCHUNG
·
2021
·Vol. 75
·期 12
·1150-1158
·
IF 2.393
Xiaoshuang Shen,Dengkang Guo,Pan Jiang,Gaiyun Li,Sheng Yang,Fuxiang Chu
Wood properties of furfurylation can be altered by reaction mechanisms of furfuryl alcohol polymer (PFA) and cell walls. Although chemical reactions between PFA and lignin have been studied, reaction mechanisms between PFA and cell wall components, including lignin, cellulose and hemicellulose are still not comprehensively understood. In order to elucidate chemical reactions regarding PFA with wood cell walls, model compounds of main cell wall components were used to investigate its reactions with PFA by 13 C NMR spectroscopy and differential scanning calorimetry (DSC). Results showed that there was no chemical bonding of PFA with either cellulose or hemicellulose. Condensations of uncrowded ring positions ( meta, ortho and para ) and side chains (α–C, β–C, β–OH, and γ–OH) of lignin with PFA did occur based on 13 C NMR spectra. Reaction enthalpy and activation energy also confirmed the condensation reactions between lignin and PFA. This study could provide design guidelines to control the chemical reactions of PFA in cell walls and lignin and, therefore, improve the properties of furfurylated wood.
研究领域:
材料科学
·
化学
·
木材科学与技术
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DOI
高影响因子
HOLZFORSCHUNG
·
2014
·Vol. 69
·期 4
·449-455
·
IF 2.339
Wendi Liu,Tingting Chen,Tianshun Xie,Fuwen Lai,Renhui Qiu
A novel method for the preparation of bamboo fibers (BF) has been investigated that includes crushing, rolling, and other combing techniques with 1,4-butanediol as a dispersant. The fibers were treated by oxygen plasma to improve their interfacial adhesion to unsaturated polyester (UPE) resins. Composites were prepared from the plasma treated fibers (BF tr ) and UPE by hand lay-up compression molding. BF tr significantly increased the tensile strength, flexural strength, and flexural modulus of the resulting BF-UPE composites. Dynamic mechanical analysis indicated that the plasma treatment essentially increased the storage modulus and glass transition temperature of the composites. The damping parameter of the composites showed a decreasing trend in the glassy region, while the opposite was true for the rubbery region. X-ray diffraction analysis indicated that the treatment did not change the crystal structures within the fibers but increased slightly their crystallinity indices. X-ray photoelectron spectroscopy analysis revealed that the surface of BF tr had a higher oxygen concentration and oxygen/carbon ratio than that of BF. The scanning electron microscopy graphs of the tensile-fractured surface of the composites demonstrated an improved interfacial adhesion between BF tr and UPE resins.
研究领域:
材料科学
·
表面改性技术
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DOI
高影响因子
危险品化学品经营许可证（带存储）