MATERIALS CHEMISTRY AND PHYSICS
·
2021
·
IF 4.094
Faqiang Shi,Limeng Liu,Jiandong Wu,Junfeng Hou,Yujin Wang
TaC x (x = 0.5, 0.55, 0.6 and 0.7) ceramics with 20 mol% Al addition were prepared by hot pressing TaC, Ta and Al powder mixtures. Effects of the overall C:Ta ratios and the Al addition on constituent phases, microstructures and mechanical properties of the consolidated materials were examined. Results showed that O impurity contained in the starting powders was collected in form of Al 2 O 3 due to strong affinity of O with Al. The TaC x -Al composites were easy to densify due to presence of molten Al at its melting point ( T m = 660 °C) and a transient Al–Ta eutectic liquid at higher temperatures. After densification, the metallic liquids were eliminated ultimately by formation of refractory Ta 4 AlC 3 via reaction of Al, Ta and TaC. Reactions between the remnant Ta and TaC after Ta 4 AlC 3 formation resulted in ζ-Ta 4 C 3-z or h-Ta 2 C depending on the initial C:Ta ratio. The Ta 4 AlC 3 compound was compatible with the tantalum carbides. Microstructures of the TaC x -Al (x = 0.5–0.7) composites were consisted of ζ-Ta 4 C 3-z and Ta 4 AlC 3 fine lamellar grains to benefit the mechanical properties of the composites. The TaC 0.7 –20mol% Al composition had satisfying mechanical properties (flexural strength 613 ± 28 MPa and fracture toughness 11.2 ± 0.8 MPa m 1/2 ). TG-DSC evidenced an increase in oxidation resistance of the TaC x ceramics by the addition of 20 mol% Al.
研究领域:
材料科学
·
机械工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2020
·
IF 4.495
Zhengdi Jiang,Tianheng Xiong,Zimei Bai,Dandan Zhao,Wenping Yang,Yun Peng,Hui Dan,Yi Ding,Tao Duan
Zircon (ZrSiO 4 ) ceramics have been widely used in the field of radioactive waste immobilization and ceramics industry. However, preparation of zircon ceramics suffers from low yield due to the variable Si/Zr molar ratio. Herein, we reported preparation of x SiO 2 /ZrSiO 4 (0 ≤ x ≤ 0.3) ceramics using SiO 2 and ZrO 2 as raw materials. The effects of Si/Zr molar ratio and sintering temperature on the phase formation, phase and microstructure evolutions were investigated. The results indicated that zircon formation efficiency increased with increasing Si/Zr molar ratio from 1 to 1.2, while decreased with increasing Si/Zr molar ratio from 1.2 to 1.3. The as-prepared ceramics with Si/Zr molar ratio of 1.1 and 1.2 were single zircon phase, while with Si/Zr molar ratio of 1 and 1.3 exhibited coexistence of zircon and cristobalite phases. The grain growth and compactness can be enhanced by increasing Si/Zr molar ratio. Furthermore, the relative densities increased with increasing Si/Zr molar ratio.
研究领域:
材料科学
·
核废料处理
✓ 已验证
DOI
高影响因子
Crystals
·
2023
·Vol. 13
·期 7
·1099
·
IF 2.7
Li He,Niansheng Huang,Donglin Lu,Pengfei Sheng,Wenjing Zou
Due to its high bonding energy and low self-diffusion coefficient, silicon nitride (Si3N4) ceramics cannot form a dense structure with prolonged high-temperature insulation or by raising the sintering temperature. To improve the density of the sintered Si3N4ceramics, additives are added to promote the rearrangement–dissolution–precipitation process of the crystal grains. However, the liquid phase formation temperature of different sintering aid chemical compositions varies, making it challenging to isolate the mechanism and the effect of liquid phase formation temperatures on sintering. Hence, we developed three sintering aids, namely Y2O3-Al2O3(YA), Y2Si2O7(Y2S), and Y2Si2O7-Al6Si2O13(Y2SM), with homologous elements and different liquid phase formation temperatures. These sintering aids can form a liquid phase with SiO2on the surface of Si3N4at varying temperatures. We analyzed the sintered Si3N4ceramic’s density, volume shrinkage rate, and microstructure to verify the YA’s lower liquid phase formation temperature effect, providing more rearrangement time and increasing sintering density. Conversely, sintering aids with too low liquid phase formation temperatures are more prone to volatilize during high-temperature sintering stages, thereby reducing sintering density. This research found that different liquid phase formation temperatures do not affect the α→β phase transition temperature of Si3N4ceramics. We also evaluated the Y2S sintering aid contents’ effect on Si3N4ceramics sintering. The results revealed that aiding sintering with too little Y2S content is insufficient for liquid phase production, and hence does not improve sintering density. Conversely, excessive liquid phase can improve density and refine grain size but increases weight loss rate during sintering due to volatilization.Keywords:liquid phase sintering;liquid phase formation temperature;sintering aids;silicon nitride sintering
研究领域:
材料科学
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陶瓷工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2020
·Vol. 31
·期 23
·21693-21701
·
IF 2.22
Zhou Fuming,Wang Hao,Guo Jianming,Yang Hui,Li LingFeng,Zhang Qilong
Microwave dielectric ceramics Sr 2 CeO 4 + n wt% Li 2 CO 3 —Bi 2 O 3 (LB) (1 ≤ n ≤ 4, L: B = x : y , weight ratio) were prepared by a traditional solid-state reaction method. The effects of LB additives on the phase formation, microstructure, sintering behavior, and microwave dielectric properties of Sr 2 CeO 4 ceramics were investigated. The sintering temperature can be reduced obviously from 1270 to 950 °C because of the liquid phase formation of LB. Single-phase Sr 2 CeO 4 ceramics with dense structure and homogenous grains were obtained by adding 1wt% LB. With LB content increasing, Q × f values would decrease because secondary-phase SrCeO 3 appeared in the ceramics. When the content of LB was fixed at 1 wt%, the sintering temperature and Q × f value would decrease simultaneously with the ratio of Li 2 CO 3 increasing. Desirable performances of Sr 2 CeO 4 + 1wt% LB ceramics: ( ε r = 14.36, Q × f = 102,023 GHz and τ f = − 66.42 ppm/°C, L:B = 2:8) and ( ε r = 13.56, Q × f = 70,109 GHz, τ f = − 64.17 ppm/°C, L:B = 8:2) can be achieved at 1075 °C and 950 °C, respectively, suggesting that Sr 2 CeO 4 –LB ceramics have a great potential for millimeter-wave applications.
研究领域:
材料科学
·
陶瓷
·
微波工程
✓ 已验证
DOI
高影响因子
MATERIALS CHEMISTRY AND PHYSICS
·
2024
·
IF 4.3
Yonghui Yu,Jie Wei,Xianghui Yan,Yuhong Chen,Biao Zhang,Yujin Wang,Feng Ye,Limeng Liu
TaB 2 –SiC composites with 0–20 wt% SiC contents were prepared by reaction hot pressing using Ta, B and SiC powders as starting materials. Densification, constituent phases, microstructure and mechanical properties, namely Vickers hardness, fracture toughness and flexure strength, were evaluated by means of inspection of sintering shrinkage, density measurement, XRD, SEM, TEM, HRTEM, EDS, SAED, indentation and three-point bending tests. Phase formation, including dominant (TaB 2 , SiC) and minor (TaC, glassy SiO 2 ) phases, was checked by thermodynamic assessment relevant with Ta 2 O 5 and B 2 O 3 impurities introduced into the reaction system by the starting powders. The results showed that mixtures of Ta, B and SiC powders would initiate self-propagating combustion synthesis (SPCS) at about 900 °C; a transient hold at 800 °C for 1 h could suppress this reaction. Volatilization of B 2 O 3 impurity in association with local high temperature due to SPCS helped reduce the TaC and glassy SiO 2 minor phase formation. TaB 2 –SiC composites could reach 99 % relative densities with 3 wt% SiC addition and above. Compositions with <7.5 wt% SiC additions showed uniform dispersion of SiC particles at multi-TaB 2 grain junctions while compositions with higher SiC content revealed SiC segregation. Bending strength of 503 MPa and fracture toughness of 6.69 MPa⋅m 1/2 could be reached with 7.5–20 wt% SiC addition.
研究领域:
材料科学
·
机械工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL AND ENGINEERING DATA
·
2021
·
IF 2.694
Huijuan Li,Shunguo Qiu,Li Chen,Taotao Fan,Xiong Peng,Zongcheng Yan
A deep eutectic solvent (DES)-based aqueous biphasic system (ABS) denotes a clean and highly biocompatible separation and purification technology, but the explanations of the phase formation mechanism and phase behavior of a DES-based ABS are incomplete. To improve the study of the formation mechanism of a DES-based ABS, a new ABS composed of n-propanol (NPA) and DES with betaine as the hydrogen-bond acceptor (HBA) and polyol as the hydrogen-bond donor (HBD) was formed. The phase formation mechanism of this new ABS and the stability of the DES in the ABS were studied. Betaine and three polyols are hydrophilic (log KOW < 0), whereas NPA is relatively hydrophobic (log KOW > 0). Two phases were formed, because the two components of DES were incompatible with the NPA. The molar ratio of the HBA and HBD in the two phases differed, but in the bottom phase of this ABS, the stoichiometric ratio of HBA and HBD was the same as their initial ratio. Under certain conditions, this novel ABS was considered a ternary-like system. The combination of a series of factors, such as HBD hydrophilicity, molar volume, molecular weight, and initial molar ratio of HBA and HBD, affected the final stoichiometric ratio of HBA and HBD in the top phase.
研究领域:
化学工程
·
分离科学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2016
·
IF 2.758
Bo Huang,Hsueh-Liang Chu,Moo-Chin Wang,Chao Liu,Weng-Sing Hwang,Xiujian Zhao
The phase formation, growth kinetics and optical properties of 0.5ZnO-0.5CdO thin films have been investigated by X-ray diffraction (XRD) and UV–vis spectrophotometry. The XRD results show that all 0.5ZnO-0.5CdO thin films are composed of CdO as the major phase and ZnO as the secondary phase. Moreover, after annealing of the 0.5ZnO-0.5CdO thin films at 723 K for 45 min and 773 K for 30 min, the minor phase of CdSiO 3 also appeared. The average activation energy of CdO grain growth in 0.5ZnO-0.5CdO thin films by the isothermal method is 10.51±1.17 kJ/mol. The average optical transparency was nearly 80% for the wavelength range from 500 nm to 900 nm. The grain size of CdO on the band gap energy for 0.5ZnO-0.5CdO thin films after annealing has a critical value, namely 15.9 nm. When the grain size of CdO is smaller than 15.9 nm, the band gap energy decreases, showing a redshift effect. Conversely, the band gap energy increases when the grain size of CdO is greater than 15.9 nm, showing a blueshift effect.
研究领域:
材料科学
·
物理化学
✓ 已验证
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Xiaoyang Hu,Haowei Xu,Zhuang Wang,Qiao Yu,Xuanhao Huang,Xingyue Liu,Qiang Tian,Songdong Ding
Diglycolamide (DGA) extractants, especially TODGA ( N , N , N′ , N′ ‐tetraoctyl diglycolamide), show significant potential in high-level liquid waste treatment. However, their limited loading capacity for trivalent lanthanides (Lns) and actinides (Ans) often leads to detrimental emulsification or third phase formation, hindering their practical applicability. Herein, TOOEDGA ( N , N , N’ , N’ -tetra(2-(octyloxy)ethyl)diglycolamide), a new DGA extractant with long C-chains combined with ether bonds, exhibits superior extraction performance towards Am 3+ and Eu 3+ in HNO 3 solution compared to TODGA. The factors influencing the formation of a third phase during the extraction process were investigated. It has been shown that TOOEDGA has a greater loading capacity for Lns 3+ and can tolerate a wider concentration range of HNO 3 . Additionally, the aggregation behavior of DGAs in n -dodecane was also studied using dynamic light scattering and small-angle X-ray scattering, revealing that the reverse micelles formed by TOOEDGA are more stable than those formed by TODGA. Moreover, under similar conditions, TOOEDGA molecules do not aggregate further to generate rod-like reverse micelle aggregates like those observed with TODGA, which is beneficial to inhibit the formation of the third phase. Consequently, our results suggest that TOOEDGA holds great promise as an alternative DGA extractant for practical industrial applications.
研究领域:
化学
·
核化学与放射化学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF RADIOANALYTICAL AND NUCLEAR CHEMISTRY
·
2025
·
IF 1.6
Huang Xuanhao,Liu Xingyue,Wang Yiting,Wang Zhuang,Yu Qiao,Zhou Hang,Li Rui,Ding Songdong
As one of the main radiolysis products of tri-isoamyl phosphate (TiAP) in the spent fuel reprocessing process, di-isoamyl phosphate (DiAP) can lead to a significant deterioration of TiAP in extraction performance. In this context, the effect of DiAP on the extraction and stripping behaviors of U(VI), Th(IV), and Zr(IV) for 1.1 mol/L TiAP/ n -dodecane organic phase was investigated for the first time. It has been shown that DiAP can increase the ability of TiAP to extract metal ions and inhibit the stripping, as well as promote the formation of interfacial deposition. Combined with the results of DLS, FT-IR, 31 P NMR, ESI-MS and elemental analysis, the role of DiAP in the formation of interfacial deposition was also elucidated.
研究领域:
化学工程
·
核能科学与工程
·
放射化学
✓ 已验证
DOI
高影响因子
Journal of Physical Chemistry C
·
2021
·
IF 4.126
Yiyang Liu,Rongshan Lan,Changwu Dong,Kun Wang,Xiaobin Fu,Hongtao Liu,Yuan Qian,Jianqiang Wang
The new salt heating magic-angle spin (MAS) system for high-temperature nuclear magnetic resonance (HT-NMR) is achieved by a laser heating beam coupled with optical fiber. The formation of a sodium ion-doped crystal KF phase is revealed in FLiNaK ternary eutectic salt (46.5%LiF–11.5%NaF–42.0%KF), which is considered unable to exist at room temperature according to its phase diagram. Density functional theory (DFT) simulation proved that Na+ ion-doped crystal is clearly ascertained to develop with the solidification of the melt. Temperature dependence, relaxation, and variable contact time cross-polarization NMR studies provide insights into the unique dynamics and the spatial scale of the doped Na+ ions in KF crystals, which exhibit faster ionic vibration due to the weakening of coordinated interactions from the ambient F– ions.
研究领域:
材料科学
·
核能工程
·
物理化学
✓ 已验证
DOI
高影响因子
ACS Applied Energy Materials
·
2019
·
IF 0
Hongjie Xu,Minjie Xuan,Weidong Xiao,Yonglong Shen,Zhenzhen Li,Zhuo Wang,Junhua Hu,Guosheng Shao
Solid electrolytes based on theoretically identified double antiperovskite phases Li6OSI2 were successfully synthesized. Experimental characterization supported the theoretical prediction that S substitution of O leads to stabilization of the double antiperovskite structure and lattice softening to significantly enhance ionic conductivity, so that the total Li+ conductivity in Li6.5OS1.5I1.5 was two to three orders better than that of the best stoichiometric antiperovskite phase Li3OCl. However, both antiperovskite and double antiperovskite materials are fundamentally susceptible to surface reconstruction, which is behind significant boundary resistances typically known for materials based on antiperovskite hali-chalcogenides. Such a surface related problem was then effectively reduced through amorphous phase formation, thus offering a feasible route to exploit the full potential of this class of new materials as competitive candidates for solid Li-ion batteries.
研究领域:
材料科学
·
固态电池研究
✓ 已验证
产品关联
DOI
RSC Advances
·
2021
·Vol. 11
·期 45
·27969-27977
·
IF 3.361
Yaoyang Liu,Sheng Liu,Zhibin Liu,Chuang Zhao,Chunhui Li,Yu Zhou,Caishan Jiao,Yang Gao,Hui He,Shaowen Zhang
A novel asymmetric diglycolamide N,N-dimethyl-N′,N′-dioctyl diglycolamide (LII) was synthesized. The Nd(III) extraction behavior from HNO3 and loading capability of the solution of LII in 40/60 (v/v)% n-octanol/kerosene were studied. Analyses by the slope method, ESI-MS, and FT-IR indicated that, similar to the previously studied isomer ligand N,N′-dimethyl-N,N′-dioctyl diglycolamide (LI), 1 : 3 Nd(III)/LII complexes formed. Under the same experimental conditions, the distribution ratio and limiting organic concentration of LII towards Nd(III) were smaller than those of LI, but the critical aqueous concentration of LII was larger, which implies that LII exhibited poorer extraction and loading capabilities towards Nd(III) than LI, and LII has a tendency to be less likely to form the third phase. The quasi-relativistic density functional theory (DFT) calculation was performed to provide some explanations for the differences in their extraction behaviors. The electrostatic potential of the ligands indicated that the electron-donating ability of the amide O atoms in LII displayed certain differences compared with LI. This inhomogeneity in LII affected the interaction between LII and Nd(III), as supported by QTAIM and bonding nature analysis, and it seemed to reflect in the extraction performance towards Nd(III).
研究领域:
化学
·
材料科学
✓ 已验证
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）