TRIBOLOGY INTERNATIONAL
·
2021
·
IF 4.872
Yinglei Wu,Tao Sun,Zhongyi He,Xiangqiong Zeng,Tianhui Ren,Erik de Vries,Emile van der Heide
Graphene oxide (GO) underwent a single and double-side modification with octadecylamine (ODA) to MGO1 and MGO2 respectively. MGO1 and MGO2 were incorporated into the O/W base emulsion respectively to change the composition of the boundary layer and the oil phase. It was found that the tribological properties of MGO1-emulsion were better than that of MGO2-emulsion. Chemical composition analysis of the worn surfaces suggests that MGO1 nanosheets might adsorb more easily onto the surface and react better with the bearing steel to produce C–N–O–Fe-containing compounds than do MGO2 nanosheets, and that MGO1 nanosheets were more actively involved in the shear process that occurs in the contact area. SEM and nanoindentation indicated that there was a non-uniform softer MGO1-tribofilm on metal substrate.
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高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
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2020
·
IF 4.65
Changyan Ji,Zhi Huang,Xiuying Tian,Hengping He,Jin Wen,Yangxi Peng
A series of red emitting phosphors Mg 3 Y 2-x Ge 3 O 12 :xSm 3+ (0≤x ≤ 0.06) were successfully synthesized. Samples Mg 3 Y 2-x Ge 3 O 12 :Sm 3+ exhibited a cubic structure pertaining to the I a-3d (230) space group and the particle sizes range from 1 μm to 5 μm. The optical properties displayed that the optimum doping concentration of Sm 3+ is 4%. The phosphor Mg 3 Y 1.96 Ge 3 O 12 :0.04Sm 3+ not only exhibited a broad band gap of 5.54 eV but also showed a high color purity of 97.6%. In addition, the strongest emission intensity located at 566 nm belonged to the 4 G 5/2 → 6 H 5/2 transition when excited at 405 nm. Thermal quenching test revealed that the sample Mg 3 Y 1.96 Ge 3 O 12 :0.04Sm 3+ are excellent powders with splendid thermal stability, in which only 3.6% of the PL intensity is quenched at 473 K in comparison with that of 298 K. As a result, the W-LEDs based on Mg 3 Y 1.96 Ge 3 O 12 :0.04Sm 3+ yielded a high R a of 91.1, a low CCT of 4881 K, and CIE coordinates of (0.3476, 0.3466) in a 20 mA driven current. This research work provided important guidance for the synthesis of Sm 3+ doped red component with excellent luminesce properties and high thermal stability characteristics used in W-LEDs.
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高影响因子
POWDER METALLURGY
·
2020
·
IF 1.793
Dongxue Liu,Qiqi Zhang,Longchao Zhuo,Yiheng Zhang,Yanlin Wang,Jintao Xu
In this paper, a combined processing method of mechanical alloying and infiltration was used to prepare the WCu-x wt-%SiC (x = 0.5, 1, 2, 3) composites. The microstructure, density, electrical conductivity and compressive behaviour of the composites were studied comparatively. First a decreasing and then an increasing particle growth trend was obtained, indicating that a small content of SiC below 1 wt-% was beneficial for particle refinement. Besides this, with the increase of the SiC content, both the density and electrical conductivity decreased gradually. Consistent with the particle–particle contiguity of the highest value of 0.404, the WCu-1 wt-%SiC composite showed the best compressive properties. Further electron backscattering diffraction results revealed that the ultrafine-grained SiC particles, which are distributed homogeneously in the composite with lower Schmid factor values would perturb the dislocation motion to make proliferation of more dislocations, exhibiting unordinary strain-hardening during deformation.
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高影响因子
FOOD HYDROCOLLOIDS
·
2021
·
IF 9.147
Yilan Wu,Xingzhong Zhang,Dan Qiu,Ying Pei,Yan Li,Bin Li,Shilin Liu
In this study, the effect of surface charge density of bacterial cellulose nanofibrils (BCNF) on the rheological characteristics of O/W Pickering emulsions was investigated by regulating the fibril charge density. BCNFs with different carboxylate group contents (0.66, 0.90 and 1.16 mmol/g dry cellulose, representing as TOBC-a, -b, and -c) were obtained by 2,2,6,6-tetramethylpiperidine-nitrogen-oxide (TEMPO) oxidation . These oxidized products were used as Pickering stabilizers to prepare O/W Pickering emulsions. Diffusing wave spectroscopy (DWS)-based microrheology was utilized to reflect the rheological features of emulsions. TOBC-a stabilized emulsion had a lower macroscopic viscosity, lower elasticity, and better fluidity. It was because a weaker fiber network was formed in the continuous phase during the ultrasonication emulsification . The influences of pH and ionic strength on the rheological properties of high-charged TOBC-c stabilized emulsions were also investigated. The emulsion prepared at pH 3.0 exhibited the highest viscosity. It was probably because the inter-fibrils electrostatic repulsion was weakened by the addition of HCl, and the hydrogen bonding interaction became dominant due to the protonation of carbohydrate group. At pH 11, the emulsion viscosity was lowest, which was resulted from the destruction of the intra-fibrils hydrogen bonds. With the NaCl concentration increased, the emulsion viscosity and elasticity increased. It was induced by the fact that the charge shielding effect of NaCl facilitated the formation of a tighter fibrils network in the continuous phase. These results have the potential to provide a guide for developing emulsion-based products with appropriate fluidity to broaden the practical application of emulsion.
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高影响因子
ADVANCED POWDER TECHNOLOGY
·
2019
·
IF 3.25
Zepeng Lv,Dong Liu,Yijie Wu,Run Zhang,Haibo Sun,Jie Dang,Liwen Hu
Tungsten, one of the refractory metals, has lots of excellent properties, making tungsten powders become a choice of raw material for many applications. This work reported a simple method (the salt-assisted hydrogen reduction of WO 3 powders) for preparing tungsten powders with desired morphologies and size. By adjusting the amount of additive (Y(NO 3 ) 3 ) and reduction temperature, metallic tungsten particles with different morphologies and size were obtained. It was found that both temperature and additive had apparent effects on the morphology and size of metallic W particles, and the large parallelepiped-shaped powders disappeared and large irregular blocky-shaped powders were degraded under the influence of additive. With the increase of temperature and amount of salt, particles became more dispersed and the size increased at higher temperatures, and the shape of particles was changed from spherical to polyhedral as well. On the contrary, the size of sub-particles became smaller as increasing amount of Y(NO 3 ) 3 at lower temperatures. Based on the results, the reaction and refining mechanisms for preparing tungsten were proposed as well.
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高影响因子
CERAMICS INTERNATIONAL
·
2018
·
IF 3.057
Baosong Li,Dandan Li,Wei Chen,Yuying Liu,Jun Zhang,Yulei Wei,Weiwei Zhang,Wanchun Jia
Ni-W/TiN nanocomposite coatings were successfully prepared via pulse electroplating from an electrolyte containing suspended TiN nanoparticles . The effects of applied current density and deposition time on microstructure, morphology, composition, hardness and electrochemical behaviors of the obtained coatings were investigated. Results showed that the current density and deposition time affect remarkably the electrochemical co-deposition process and then the structure and characteristics of the composites. It illustrated that the nanocomposites are uniform, compact and crack-free. The nanocomposites prepared at I a = 3 A dm −2 and t = 20 min had the finest structure, showing a fine and smooth surface. EDS mapping and XPS spectra illustrated that the TiN nanoparticles had been homogeneously dispersed throughout the coating. 2.34 wt% TiN nanoparticles were embedded in Ni–W (68.56 wt% Ni and 29.1 wt% W) alloy matrix at I a = 3.0 A dm −2 . The inclusion of TiN nanoparticles in Ni–W could promote the nucleation and cause a distinct microstructural change. The crystallite size was in the range of 11–15 nm. The average roughness value ( R a ) is 65.7 nm and 73.8 nm for coating formed at 20 min and 40 min, respectively. The electrochemical measurements illustrated that I a = 3–5 A dm −2 and t = 40–60 min was the optimal operating parameters for the excellent anti-corrosion properties of Ni–W/TiN nanocomposites. The embedded TiN in Ni–W matrix could fill defects then improve its corrosion resistance . This electrodeposited Ni–W/TiN nanocomposites possess excellent hardness and superior corrosion resistance , and is expected to be applied in aggressive environment as a protective coating.
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高影响因子
RSC Advances
·
2018
·Vol. 8
·期 20
·10907-10913
·
IF 2.936
Meng-Qing Li,Yu-Long Ma,Xiao-Xia Ma,Yong-Gang Sun,Zhi Song
In this work, a mesoporous silica microsphere (MSM) was selected as a support to prepare a bimetallic supported catalyst (15% W–5% Ni/MSM) by a co-impregnation method that was simple and easy to conduct. We wished to improve the capability of catalytic conversion of biomass into ethylene glycol (EG) and 1,2-propylene glycol (1,2-PG). 15% W–5% Ni/MSM was examined on microcrystalline cellulose (cellulose) and corn stalks in a one-pot catalytic process, and total yields of EG and 1,2-PG reached up to 82.40 wt% and 62.60 wt%, respectively. This remarkable catalytic performance of W–Ni/MSM catalyst could be attributed to the synergistic effect between the active sites of Ni and W and the unique structure of MSM, which was suitable for mass transfer and metal loading. Based on physicochemical characterizations, the metal component was well-distributed on the surface of the MSM, and the metallic Ni, W and WO3 of the fresh catalyst were converted mainly into NiWO4 during the catalytic conversion of cellulose. To shed light on the reaction mechanism of the catalyzed hydrogenation of biomass, a possible process involving the formation of HxWO3 homogeneous catalysts, cellulose hydrolysis, C–C cleavage and hydrogenation conversion to 1,2-PG and EG was illustrated. Furthermore, the reusability of W–Ni/MSM catalyst was tested and we explored the cause of decreased diols yields. In summary, this work provides important guidance to rationally design effective catalysts for biomass conversion.
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PubMed
高影响因子
FUEL
·
2015
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IF 3.52
Hao Wang,Zhenyu Yao,Xuchun Zhan,Yan Wu,Min Li
A microwave hydrothermal (MWH) method was used to deposit WO 3 onto ZrO 2 –Al 2 O 3 with various ZrO 2 contents to prepare hydrodesulfurization (HDS) catalysts with high WO 3 loading (23 wt%) close to industrial hydrotreating, for achieving high W dispersion and weak W-support interaction. The catalysts with the same WO 3 and ZrO 2 contents were prepared by a conventional impregnation (IM) method as reference. The effects of catalyst preparation methods and ZrO 2 contents on the catalyst property and dibenzothiophene HDS activity were investigated. The results show that the MWH method leads to highly dispersed octahedrally coordinated W species which are weakly linked on ZrO 2 –Al 2 O 3 and easy to be reduced; no bulk WO 3 crystallites are observed even at high ZrO 2 content (50 wt%). Therefore, it causes better sulfidation and shorter WS 2 slabs. Contrarily, the IM method induces W species to agglomerate into bulk WO 3 crystallites which are poorly dispersed and hard to be reduced, which is further aggravated by ZrO 2 . The HDS activity of the MWH-prepared catalysts significantly increases with ZrO 2 up to 40 wt% ZrO 2 . This catalyst shows 2 times higher rate constant and 1.64 times higher efficiency of HDS than the IM-prepared catalyst with the same ZrO 2 content. For the IM-prepared catalysts, the HDS activity slightly increases at small amount of ZrO 2 (10 wt%) and then decreases drastically.
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高影响因子
CRYSTENGCOMM
·
2016
·Vol. 19
·期 4
·675-683
·
IF 3.849
Bing Liu,Shuangyue Su,Wenhui Zhou,Yin Wang,Ding Wei,Lihua Yao,Yuanman Ni,Minhua Cao,Changwen Hu
The practical applications of TiO2 have been greatly suppressed by its low quantum yield, which arises from the rapid recombination of photo-induced electrons and holes, and poor solar efficiency, which is determined by its band gap. Herein, W-doped TiO2 coupled with Au nanoparticles (W-TiO2/Au) was designed and synthesized by a facile multi-step process. The W-doping in the TiO2 lattice, on the one hand, can hinder the phase transition of TiO2 from anatase to rutile structure, and the pure anatase structure is well preserved. On the other hand, W-doping can narrow the band gap of TiO2 and result in oxygen vacancies, which may act as trapping sites to retard charge recombination. Furthermore, Au loading on the surface of TiO2 can effectively suppress the recombination of photo-induced electrons and holes, leading to improvement in the quantum yields of TiO2. Benefiting from the unique dual-hybrid strategy, the W-TiO2/Au catalyst possesses a strong solar adsorption narrowed band gap, abundant active sites, strong synergetic coupling, enhanced electron transfer, and high efficiencies in H2 generation. Its maximum H2 generation rate can reach as high as 24 mmol g−1 h−1 under simulated solar light. A synergetic effect was proposed to explain the enhancement of the photocatalytic activity of TiO2.
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高影响因子
RSC Advances
·
2017
·Vol. 7
·期 32
·19815-19827
·
IF 3.108
Liya Zeng,Xin Xin,Yalin Zhang
Nanoemulsions have attracted much attention due to their wide application in commercial industries such as pharmaceutics, food, beverages and skin care. Cremophor EL has been extensively used for emulsification, protection and solubilization of various lipophilic bioactive agents. However, their anaphylactoid hypersensitivity reactions are still challenging. Therefore, the aim of this study was to develop and characterize a promising, low-level Cremophor EL-stabilized o/w nanoemulsion using the spontaneous emulsification method for oral administration. From comparing the physicochemical properties (particle size and size distribution) of their emulsions, Cremophor has better emulsifying capacity than Tween and the droplet radius of emulsions can be reduced by increasing the surfactant concentration in current systems. The impact of various short-chain alcohols (C–OH < 5) on the formation and stability of nanoemulsions was also investigated to optimize the formulations. And there is a good correlation between nanoemulsion droplet size and the surfactant packing parameter (p). The smallest droplet size with the narrowest size distribution was produced by the system containing ethylene glycol as a cosurfactant. However, preparation of nanoemulsions with ethylene glycol was a time-consuming process since it was difficult to emulsify the water-induced gel-structure. Surfactant-to-oil mass ratio and surfactant-to-cosurfactant levels had to be optimized to produce fine droplets. Moreover, there was a linear relationship between the viscosity/log P value of alcohols and droplet size. Ostwald ripening was the dominant breakdown process of nanoemulsions obtained in the ethyl oleate/Cremophor EL–butanol (3 : 2)/water system. Ostwald ripening rate was increased with increasing surfactant concentration. Dilution (100×) of this system considerably improved their stability against droplet growth. This study demonstrated that alcohol addition might be a useful tool for preparing Cremophor EL-stabilized nanoemulsions for pharmaceutical applications.
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高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2016
·
IF 3.014
Cheng Yang,Zhongfang Zhang,Guangcai Hu,Rui Cao,Xiaojuan Liang,Weidong Xiang
Currently, the non-rare-earth Mn 4+ -activated oxide red phosphor is of great interest as color converter for warm white light-emitting diodes (W-LEDs), owing to its admirable luminescent properties and low price. Herein, a novel blue-light activated Ca 14 Zn 6 Ga 10 O 35 :Mn 4+ (CZG:Mn 4+ ) phosphor, exhibiting strong red emission attributed to Mn 4+ : 2 E g → 4 A 2g spin-forbidden transition in region of 650–750 nm under 462 nm excitation, is successfully synthesized through a traditional solid-state reaction route in air. Subsequently, the microstructure and luminescent performance of this red-emitting phosphor are discussed in detail. The crystal field strength ( Dq ) and the Racah parameters ( B and C ) are carefully calculated to estimate the nephelauxetic effect of Mn 4+ suffering from the CZG host lattice. In addition, the concentration quenching and thermal quenching characteristics are also systematically investigated. After incorporating CZG:Mn 4+ and commercial Y 3 Al 5 O 12 :Ce 3+ (Ce:YAG) phosphors into a blue LED device, warm white light with high color rendering index and low correlated color temperature is successfully achieved. Therefore, the CZG:Mn 4+ phosphor can serve as color converter for use in warm W-LED applications.
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高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Shuai Yan,Sen Wang,Gaobin Liu,Qi Yuan,Kuoming Song,He Zhao,Xin Li,Rongzheng Shen
Herein, MgO–12 % TiO 2 (w) ceramics with different contents of Bi 2 O 3 –CuO sintering aid were prepared using a solid-state method. The effects of the sintering aid content on the sintering temperature and the dielectric and mechanical properties of the ceramics were studied. The material was characterized using scanning electron microscopy and X-ray diffraction and Precision LCR tester and universal testing machine and Archimedes drainage method. When the Bi 2 O 3 –CuO content was less than 9 wt%, the ceramic sample has higher dielectric properties. When the Bi 2 O 3 –CuO content was greater than 9 wt%, the dielectric properties will deteriorate. This is because Bi 2 O 3 participates in the chemical reaction between MgO and TiO 2 , forming a high dielectric loss Bi 4 Ti 3 O 7 phase. At high temperatures, Cu 2+ can easily change valence to Cu + , promoting oxygen vacancies and increasing dielectric loss in ceramic samples. The introduction of Bi 2 O 3 –CuO produces new MgTiO 3 , Mg 2 TiO 4 , and Bi 4 Ti 3 O 12 phases in the sample structure, resulting in a structure in which the MgO grains in the sample are surrounded by the new phases that appear around them. This structure fills the pores, increases density, enhances mechanical properties. The dielectric properties of the ceramics were the when the sintering temperature was 1050 °C, and the Bi 2 O 3 –CuO content was 3 wt%. The dielectric constant and dielectric loss were 11.19 and 1.17 × 10 −4 , respectively. The bending strength of the ceramic sample increased from 138.72 MPa to 179.64 MPa when the Bi 2 O 3 –CuO content was increased from 3 wt% to 15 wt%. The Bi 2 O 3 –CuO sintering aid enables MgO to be better applied in ceramic substrates.
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高影响因子
危险品化学品经营许可证（带存储）