JOURNAL OF ALLOYS AND COMPOUNDS
·
2018
·
IF 3.779
Ni Xiong,Rui Bao,Jianhong Yi,Dong Fang,Jingmei Tao,Yichun Liu
CNTs/Cu-Ti composites were fabricated successfully by spray pyrolysis , low energy ball milling and subsequent hot pressing (HP). Microstructure and mechanical properties of the composites were characterized by SEM, EDS, HRTEM , XRD, hardness and tensile tests. The results reveal that in situ generated nano-TiC particles, as a transition phase from CNTs to Cu-Ti matrix, which played a “rivet” role in enhancing the interfacial bonding between the CNTs and Cu-Ti matrix is formed in the composites. Consequently, mechanical properties of the CNTs/Cu-Ti composites are enhanced compared with alloy matrix, and an optimal balance between elevated ultimate tensile strength and impressively larger plastic deformation is achieved by adding 0.4 wt% CNTs in the composites. (ultimate tensile strength (UTS) 352 MPa, elongation 28.2%, the UTS is 39% higher than that of the Cu-Ti alloy, and the ductility increased significantly by 62%.) Finally, strengthening and toughening mechanisms are discussed. This study provides new insights into the interface structure and strength-ductility in metal-matrix composites.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2019
·
IF 4.175
Lin He,Yimin Gao,Yefei Li,Zhiwei Liu,Weiyao Zhang,Guangcan Zhou,Hongying He,Siyong Zhao,Honggang Liu,Wentao Yan
Ti(C,N)-304ss cermets with various rare earth yttrium addition were fabricated via powder metallurgy . Fe and Cr atoms dissolved into Ti(C,N) grains and formed a core-rim structure. The first-principle method was employed to calculate the lattice parameters and elastic modulus of the solid solution. The formation of solid solution not only reduced the lattice misfit between the binder phase and hard phase but also improved the hardness of hard phase. The in-situ formed nano-Y 2 O 3 particles existed at the center of Ti(C,N) grains acting as ‘mid effect’ heteromorphic nuclei. The microstructure of cermets was refined with Y addition and the abnormal growth of hard phase was suppressed. The mechanical properties were also improved with Y addition. When the Y content reached 0.3 wt%, the optimal mechanical properties were obtained with a TRS value of 1527 MPa and a hardness value of 91.7 HRA.
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Processes
·
2024
·Vol. 12
·期 9
·1879
·
IF 2.8
Huiying Yang,Xiangchao Meng
The conversion of nitrogen (N2) and water (H2O) into NH3by photocatalysis under ambient conditions has been considered an environmentally friendly strategy. However, developing effective catalysts for N2fixation is still challenging. Herein, we report a bimetallic JH Fe, Co/TiO2derived from NH2-MIL-125(Ti) by the fast Joule heating (FJH) method for visible–light–driven catalytic N2fixation. It was found that the photocatalytic N2reduction efficiency of bimetallic FC@TiO2-JH was improved, enabling an NH3yield rate of 110.14 µmol g−1h−1without any sacrificial agents. Furthermore, the rate was higher than those of Fe@TiO2-JH and Co@TiO2-JH, suggesting that the synergistic effect between Fe and Co broke the electronic equilibrium and increased the center of its d-band, enhancing electronic feedback to the antibonding π* orbitals of N2while weakening the bonding energy of N≡N. Meanwhile, the rate was about 2.75 times higher than that of FC@TiO2-TF, which was calcined in a tube furnace. It is assumed that FJH might lead to the formation of lattice defects, leading to localized charge deficiency, enhanced carrier separation, and transport. Thus, doping of Fe and Co synergistically interacted with the defects produced from FJH, facilitating the photocatalytic reduction process. As detected, it had a greater ability to separate hole–electron pairs and transferred electrons to adsorbed N2at faster rates. Our work demonstrates a prospective strategy for designing bimetallic catalysts derived from NH2-MIL-125(Ti) for N2fixation.
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THIN-WALLED STRUCTURES
·
2025
·
IF 6.6
Meng Cao,Yewei Zhang,Mingyu Liu,Xuefeng Sun,Shuo Wang,Jian Zang
The insufficient bond strength at the fiber/metal interface of fiber metal laminates (FMLs) is a primary obstacle to their widespread application. To address this issue, a strategy is proposed to introduce graphene nanoplatelets (GNPs) to enhance the bond strength at the carbon fiber/polyether ether ketone (CF/PEEK)-titanium interface. This approach comprises two main components. First, GNPs were deposited onto the surface of the titanium layer to form a micro-nanolayer using electrophoretic deposition (EPD). The effects of varying voltages, deposition times, and GNPs concentrations on the EPD results were investigated. Second, the PEEK matrix was modified with GNPs to further enhance the interfacial bond strength of CF/PEEK-titanium. The results indicated that optimal EPD parameters-30 V, 90 s, and a GNP concentration of 0.75 mg/mL-yielded the best outcomes. Under these conditions, the flexural strength, interfacial shear strength, and shear adhesion strength of FMLs improved by 201.9 %, 133.9 %, and 91.4 %, respectively, compared to unmodified FMLs. When combining GNPs-modified PEEK with EPD, these properties increased further, with flexural strength, interfacial shear strength, and shear adhesion strength enhanced by 281.7 %, 238.7 %, and 112.4 %, respectively, compared to unmodified FMLs. Molecular dynamics simulations were performed to further investigate the role and mechanism of GNPs in the GNPs/PEEK/titanium ternary system. The simulations revealed that combining a GNPs-modified matrix with EPD significantly enhances the system's interfacial energy. Moreover, GNPs substantially influence the torsional behaviour of the PEEK main chain. These combined experimental and simulation results offer new insights into applying GNPs in composite materials.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2025
·
IF 6.3
Changyan Guo,Cheng Guo,Shuai Yang,Naeem Akram,Yonghong Zhang,Jide Wang
Controlling the excessive oxidation of 1,4-Benzenedimethanol (1,4-BDM) to selectively produce high-value-added 4-hydroxybenzaldehyde (4-HB) under mild conditions while simultaneously generating H 2 is a challenging problem. In this study, it was found that incorporating Ni into cadmium sulfide (CdS) significantly reduces the bandgap of CdS and adjusts its conduction band position, yet still leads to over-oxidation of 1,4-BDM. To enhance selectivity, we designed and synthesized a bifunctional photocatalyst, CdS-Ti/Ni, with a petal-like structure by integrating both Ni and Ti with CdS. This composite exhibits a bandgap of 2.3 eV, and the synergistic effects of Ti and Ni result in more favorable valence and conduction band positions, thereby demonstrating superior photocatalytic efficiency and selectivity. Within the first 30 minutes, the bifunctional CdS-Ti/Ni achieved a 73 % selectivity for 4-HB. The H 2 evolution rate reached 20.2 mmol·g −1 ·h −1 , which is 13 times higher than that of pure CdS. This study demonstrates that bimetal doping can adjust the energy band structure, photocatalytic H 2 production efficiency and oxidation selectivity of semiconductor materials, offering valuable insights for the design of efficient bifunctional photocatalysts.
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MATERIALS & DESIGN
·
2017
·
IF 4.364
Jie Zhang,Zhenxing Yue,Yu Luo,Xiaohua Zhang,Longtu Li
Relaxation phenomena in dielectrics are well known to be closely related to their defect chemistry. However, the relaxation behavior of microwave dielectrics has seldom been considered, despite these materials being an important member of the electroceramic family. Here, the relaxation behavior of the typical microwave dielectric ceramic barium tetratitanate (BaTi 4 O 9 ) was investigated. Significant thermally stimulated relaxation was observed in both dielectric spectroscopy and thermally stimulated depolarization current (TSDC) measurements, and the correlation between relaxation and defect behavior was addressed. TSDC characterization revealed that defect dipoles [(Ti Ti ' )−(V O •• )] with activation energies ( E a ) of 0.32–0.36 eV appeared at low temperature, while in-grain and across-grain boundary oxygen vacancies (V O •• ) appeared at higher temperature, yielding E a of 0.30–0.48 eV and 0.65–1.01 eV, respectively. It was further believed that these two types of defects, (Ti Ti ' )−(V O •• ) and V O •• , were correspondingly responsible for the dielectric relaxation observed at low and high temperature. The relaxation behavior of several typical Ti-containing microwave dielectrics, such as BaTi 4 O 9 , TiO 2 , MgTiO 3 and Ca 0.8 Sr 0.2 TiO 3 , was compared, which suggests that microwave dielectric performance and defect behavior are closely related to the connections of TiO 6 octahedra in the materials.
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ELECTROCHIMICA ACTA
·
2017
·
IF 4.798
Lianghao Li,Zhuangpeng Huang,Xiaoxiao Fan,Zhen Zhang,Rongni Dou,Shulong Wen,Yuan Chen,Yuancai Chen,Yongyou Hu
An optimized metal oxide electrode (Ti/SnO 2 -Sb-Pd) was prepared via thermal decomposition and used in the electrochemical degradation of Ni-EDTA. The electrode was characterized by SEM, XRD, XPS, and electrochemical characterizations including linear-sweep voltammetry (LSV), cyclic voltammetry (CV) and chronopotentiometry (CP) techniques. It was found that Pd doping could effectively change the surface morphology and lattice parameters of the metal oxide electrode. Pd can facilitate the entry of more Sb into SnO 2 crystals and promote the reduction of Sb from the +5 to the +3 state. The interaction of these metals raised the oxygen evolution potential (OEP) and electrochemical surface area of the electrode, in addition to reducing the degradation potential and increasing the degradation current of Ni-EDTA. When the molar ratio of Pd:Sn was 2.5%, the electrode could simultaneously degrade 87.5% of Ni-EDTA and recycle 17.9% of elemental Ni on the cathode within 120 min. At the same time, with Pd doping, the lifetime of the electrode was increased more than 40 times, demonstrating good potential for application in industry.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2016
·
IF 8.328
Yanghe Fu,Long Sun,Huan Yang,Lai Xu,Fumin Zhang,Weidong Zhu
The Ni-doped NH 2 -MIL-125(Ti) catalyst was developed for the photocatalytic aerobic oxidation of aromatic alcohols upon visible light irradiation. The results show that different aromatic alcohols can be effectively transformed to their corresponding aldehydes with almost absolute selectivity using O 2 as the oxidant over Ni-doped NH 2 -MIL-125(Ti) upon visible light irradiation. Compared with the parent catalyst NH 2 -MIL-125(Ti), Ni-doped NH 2 -MIL-125(Ti) exhibits a significantly enhanced photocatalytic activity for the selective oxidation of aromatic alcohols. Preliminary studies indicate that the doping of Ni nanoparticles into NH 2 -MIL-125(Ti) could improve the visible-light harvesting, charge-separation, and electron-transport of the resultant catalyst, leading to the enhanced photocatalytic activity. The current work provides some guidance in the development of MOF-based photocatalysts for organic syntheses.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2017
·
IF 3.133
Li-Feng Zhu,Bo-Ping Zhang,Shun Li,Gao-Lei Zhao
The (1- x )Bi 1+ y (Fe 0.96 Mg 0.02 Ti 0.02 )O 3 - x BaTiO 3 (abbreviated as B 1+ y FMT- x BT) system was designed to explore the morphotropic phase boundary (MPB) separating rhombohedral ( R ) and tetragonal ( T ) phases, and the mechanism of performance enhancement. The phase structure of samples was discreetly investigated by X-ray diffraction, and Rietveld refinement results of the XRD data revealed that the B 1+ y FMT- x BT ceramics consist of an R phase at x = 0.24, two R and T phases at 0.26 ≤ x ≤ 0.32, and a single T phase at x = 0.34. Because of the MPB and the improvement of resistivity with adding excess Bi compensation, excellent piezoelectric properties of d 33 = 198 pC/N and k p = 30.9%, as well as high Curie temperature T C = 497 °C were achieved in the B 1+ y FMT- x BT system at x = 0.30 and y = 0.02. Here, the large d 33 = 198 pC/N which is the maximum value for the BF-BT-Bi(Mg,Ti)O 3 system so far, and high T C = 497 °C suggest that Bi(Fe,Mg,Ti)O 3 -BaTiO 3 ceramics have good prospects in high-temperature piezoelectric devices.
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APPLIED CATALYSIS A-GENERAL
·
2017
·
IF 4.339
Baohuai Zhao,Rui Ran,Xingguo Guo,Li Cao,Tengfei Xu,Ze Chen,Xiaodong Wu,Zhichun Si,Duan Weng
Mn/Ce/Ti and Mn/Ce/Nb/Ti catalysts were synthesized using a precipitation method and their catalytic activities for NO selective reduction with NH 3 at low temperatures were evaluated. Nb doping not only improved the activity of the catalyst over a wide temperature range but also restricted the generation of NO 2 and N 2 O. The Mn/Ce/Nb/Ti catalyst displayed 100% NO conversion from 150 to 250 °C and >90% N 2 selectivity below 250 °C. The specific surface area of the catalyst was increased and its surface acidity was strengthened after Nb doping. Moreover, Nb doping increased the NO oxidation ability and lowered the NH 3 oxidation activity of the catalyst. All the above factors contributed to enhancing the overall NH 3 -SCR performance of the Mn/Ce/Nb/Ti catalyst compared with that of the Mn/Ce/Ti one. The long-term stability and resistance to H 2 O and SO 2 of the Mn/Ce/Nb/Ti catalyst were also evaluated.
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RSC Advances
·
2014
·Vol. 4
·期 29
·15216-15224
·
IF 3.708
Chong-Wen Jiang,Xin Zhong,Zheng-Hong Luo
5-Hydroxymethylfurfural (5-HMF) which can be produced from cellulose is considered as one of the promising green platform chemicals. In this work, the conversion of cellulose to 5-HMF was carried out through hydrolysis in a batch reactor using the SO42−/Ti-MCM-41 catalyst at a temperature of 463–503 K. Two analytical techniques including the 3,5-dinitrosalicylic acid (DNS) method and high performance liquid chromatography (HPLC) were employed to track the time evolution of the main reagents, i.e., cellulose, 5-HMF and reducing sugar. Based on the typical kinetic experiments for the cellulose hydrolysis, a comprehensive hydrolysis mechanism was introduced to describe the heterogeneous hydrolysis of cellulose to 5-HMF. A corresponding kinetic model was proposed on the basis of the hydrolysis mechanism and the mass balance law. The results show that the predicted data obtained via the suggested model agree well with the experimental results. In addition, some data from the open reports were referred for further model verification in this work. The kinetic model suggested in this work is a mechanism model for the heterogeneous catalytic cellulose hydrolysis process, which is different from the previous first-order kinetic model.
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RSC Advances
·
2014
·Vol. 4
·期 81
·42764-42771
·
IF 3.708
Yana Liu,Jinxin Zou,Xiaoqin Zeng,Wenjiang Ding
A Mg–Ti nano-composite has been co-precipitated from a tetrahydrofuran (THF) solution containing anhydrous magnesium chloride (MgCl2), titanium tetrachloride (TiCl4) and lithium naphthalide (LiNp) as the reducing agent. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), and pressure-composition-temperature (PCT) techniques are used to characterize phase components, microstructure and hydrogen sorption properties of the composite. The co-precipitated Mg–Ti nano-composite contains nearly 1.0 wt% of Ti distributed homogeneously on the surface or inside Mg particles having an average particle size of about 50 nm. Orthorhombic γ-MgH2 phases and tetragonal γ-TiH2 phases are obtained when the Mg–Ti nano-composite is hydrogenated at 75 °C. PCT measurements reveal the superior hydrogen absorption property of the Mg–Ti nano-composite: its maximum hydrogen capacity can reach up to 6.2 wt% within 2 h at room temperature under a hydrogen pressure of 3 MPa. The activation energy for hydrogen absorption is determined to be 50.2 kJ mol−1 H2. The hydrogenation and dehydrogenation enthalpies of the nano-composite are calculated to be −73.0 ± 1.8 and 75.8 ± 4.7 kJ mol−1 H2, close to the standard values for Mg (−74.1 ± 2.9 kJ mol−1 H2). The catalytic effects from the co-precipitated Ti and the tetragonal γ-TiH2 formed during the hydrogenation process lead to extremely fast absorption kinetics at room temperature.
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