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arXiv 2018年

作者： Huang, Zhifeng Chen, Fei Shen, Qiang Zhang, Lianmeng Rupert, Timothy J. State Key Lab of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan430070 China Department of Mechanical and Aerospace Engineering University of California IrvineCA92697 United States Department of Materials Science and Engineering University of California IrvineCA92697 United States

Most research on nanocrystalline alloys has been focused on planned doping of metals with other metallic elements, but nonmetallic impurities are also prevalent in the real world. In this work, we report on the combined effects of metallic dopants and nonmetallic impurities on grain boundary energy and strength using first-principles calculations, with a Σ5 (310) grain boundary in Cu chosen as a model system. We find a clear correlation between the grain boundary energy and the change in excess free volume of doped grain boundaries. A combination of a larger substitutional dopant and an interstitial impurity can fill the excess free volume more efficiently and further reduce the grain boundary energy. We also find that the strengthening effects of dopants and impurities are dominated by the electronic interactions between the host Cu atoms and the two types of dopant elements. For example, the significant competing effects of metal dopants such as Zr, Nb, and Mo with impurities on the grain boundary strength are uncovered from the density of states of the d electrons. As a whole, this work deepens the field's understanding of the interaction between metallic dopants and nonmetallic impurities on grain boundary properties, providing a guide for improving the thermal stability of materials while avoiding embrittling effects. Copyright © 2018, The Authors. All rights reserved.

关键词： Impurities

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1D carbon [email protected] 2 core-shell nanocomposites with enhanced photocatalytic activity toward CO 2 reduction

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Journal of Alloys and Compounds 2018年 746卷 168-176页

作者： Jinfeng Zhang Junwei Fu Shifu Chen Jiali Lv Kai Dai State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan Hubei 430070 PR China College of Physics and Electronic Information Huaibei Normal University Huaibei Anhui 235000 PR China College of Chemistry and Material Science Huaibei Normal University Huaibei Anhui 235000 PR China Hefei National Laboratory for Physical Sciences at the Microscale University of Science and Technology of China Hefei 230026 PR China

More and more serious energy crisis and greenhouse effect force people to find the appropriate solutions. Photocatalytic reduction of CO 2 into hydrocarbon fuels is one of the most potential strategies. In this paper, novel one-dimensional (1D) carbon [email protected] 2 core-shell nanocomposites have been prepared via electrospun synthesis of carbon nanofibers core followed by in situ growth of TiO 2 shell, which exhibit a 2.3-fold higher photocatalytic activity than the pure TiO 2 . The increase of catalytic performance attributed to higher specific surface areas of carbon [email protected] 2 core-shell nanocomposites for providing more surface-active sites. Moreover, the black carbon nanofibers promote light absorption, and the light energy can be converted into heat energy that can speed up the diffusion of reactants and products. Most importantly, the carbon nanofibers with good electrical conductivity can speed up the separation of the photo-induced electron and hole pairs in photocatalyst. This work provides a good synthesis of 1D core-shell heterostructure, and proves that the carbon nanofibers can be an ideal cocatalyst for enhancing photocatalytic CO 2 reduction performance of TiO 2 .

关键词： Composite materials Chemical synthesis X-ray diffraction CO 2 Photocatalytic reduction

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Effect of SiC Content on the Microstructure and Properties of Zr2Al4C5/SiC Composites in situ Fabricated by Spark Plasma Sintering

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IOP Conference Series: materials Science and Engineering 2019年第1期678卷

作者： Qilong Guo Jing Wang Junjun Pei Junguo Li Lianmeng Zhang Key Laboratory of New Building Materials and Building Energy Efficiency of Gansu Province School of Civil Engineering Northwest Minzu University Lanzhou 730124 P. R. China State Key Lab of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 P. R. China

Zr2Al4C5/SiC composite ceramics were successfully fabricated from the powder mixture of Zr, Al, C and SiC by spark plasma sintering method. The composition-dependent densification, phase evolution, microstructure and mechanical properties of the composite ceramics were studied. With increasing the SiC content in the starting powder mixture, the densification behavior of sintered samples was promoted. It is found that the as-sintered products are mainly composed of Zr2Al4C5 matrix and SiC reinforcement, and the fine SiC particles tend to disperse on the matrix grain boundaries. Besides, the addition of SiC particles can evidently hinder the coarsening of Zr2Al4C5 grains. Both the Vickers hardness and Young's modulus of composites ceramics gradually increase as increasing the SiC content. The fracture toughness of the composites decreases first then increases with the increase in the SiC and the Zr2Al4C5/30vol%SiC sample possesses the maximum value of 4.4MPam1/2.

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Influence of the content of ZrxAlyCz on properties of ZrB2-ZrxAlyCz Composite Ceramics Fabricated by Spark Plasma Sintering

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IOP Conference Series: materials Science and Engineering 2019年第1期678卷

作者： Qilong Guo Jianli Pang Jizhong Gan LI Junguo Lianmeng Zhang Key Laboratory of New Building Materials and Building Energy Efficiency of Gansu Province School of Civil Engineering Northwest Minzu University Lanzhou 730124 P. R. China State Key Lab of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 P. R. China

ZrB2/ZrxAlyCz composite ceramics with different volume contents of ZrxAlyCz were fabricated by the spark plasma sintering. The sintering behavior, microstructure, mechanical properties and oxidation resistance were studied. The results indicated that sinterability of the composites was remarkably improved by addition of ZrxAlyCz compared to the single-phase ZrB2 ceramic. As the content of ZrxAlyCz increased, both the Vickers hardness and Young's modulus of the composites first increased and then decreased. The fracture toughness of the ZrB2-40vol% ZrxAlyCz composite was 3.56 MPam1/2, which increased by approximately 70% compared to the monolithic ZrB2 ceramic. As increasing the content of ZrxAlyCz, the oxidation resistance of composite ceramics was obviously enhanced. The oxidation-resulted increase in weight of composite ceramic with 20vol% ZrxAlyCz was the best performance in oxidation resistance at 1500 °C. The high-temperature oxidation resulted in dense and stable Al-B-O glass due to adding ZrxAlyCz into the composite ceramics, those resulting products effectively blocked the oxygen atoms entering into the ceramic matrix.

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Thermal reaction and phase evolution of APP/Al(OH)3/α-SiO2 6th

Thermal reaction and phase evolution of APP/Al(OH)3/α-SiO2

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6th Annual Meeting on Testing and Evaluation of advanced materials, TEIM 2015

作者： Hu, Sheng Sun, Wanwan Chen, Fei Li, Junguo Shen, Qiang Zhang, Lianmeng State Key Lab. of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan430070 China

ISBN: (纸本)9783038357278

The thermal reaction and phase evolution of APP/Al(OH)3/α-SiO2 with different mass ratios during heating were studied by TG, FTIR, XRD and SEM, respectively. When the temperature is not higher than 300°C, mass ratio of mAPP:mAl(OH)3:mSiO2 has no effect on the phase evolution of APP/Al(OH)3/α-SiO2 and the main interaction product is AlNH4HP3O10. APP/Al(OH)3/α-SiO2 with lower content of APP, appears larger weight loss rate due to the thermal decomposition of Al(OH)3. The thermal reaction of APP/Al(OH)3/α-SiO2 is significantly influenced by the APP content as temperature rises to higher than 300°C. The decomposition products of APP can chemically interact with Al(OH)3 to generate Al2P6O18 and Al(PO3)3 during 600°C ∼900°C. When the content of APP increases, much more APP can chemically react with Al(OH)3 and also with part of α-SiO2 to generate SiP2O7. SEM shows the relatively dense microstructure due to micro-bridges of liquid phase with phosphate content increasing. © 2016 Trans Tech Publications, Switzerland.

关键词： Silica

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Control of preferential orientation of La1-xSrxMnO3 thin films by pulsed laser deposition 9th

Control of preferential orientation of La1-xSrxMnO3 thin fil...

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9th China International Conference on High-Performance Ceramics, CICC 2015

作者： Zhu, Yaxiang Wang, Chuanbin Shen, Qiang Zhang, Lianmeng State Key Lab. of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan430070 China

ISBN: (纸本)9783035710656

La1-xSrxMnO3 (LSMO) thin films were grown on (100)- and (110)-oriented MgO substrates by pulsed laser deposition, so as to control the preferential orientation of the films. At the optimum deposition temperature (Td=923K), LSMO thin films with a dense texture and a smooth surface were prepared. The XRD patterns and X-ray pole figures indicated that the LSMO thin films were epitaxially grown on MgO substrates, due to the small lattice mismatch between the films and substrates. The possible orientation relationships were found to be LSMO (100)[010] // MgO (100)[010] and LSMO (110) [110] // MgO (110) [110], as for the (100) and (110) MgO substrates, respectively. © 2016 Trans Tech Publications, Switzerland.

关键词： Pulsed laser deposition

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Austenite grain growth and grain size distribution in isothermal heat-treatment of 300M steel

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Procedia Engineering 2017年 207卷 663-668页

作者： R.C. Chen C. Hong J.J. Li Z.Z. Zheng P.C. Li State Key Lab. of Material Processing and Die & Mould Technology Huazhong University of Science & Technology Wuhan 430074 China China National Erzhong Group Cooperation Deyang 618000 China

In order to investigate the austenite grain growth behavior in isothermal heat-treatment of 300M steel, experiments under different temperatures are conducted. The influences of time, temperature and initial grain size on both normal and abnormal growth of grains in heat-treatment of 300M steel are analyzed. Grain size distribution are modeled using a model which is a combination of the Sellars model and the Anelli model. Results show the model is capable of calculate grain size distribution as well as average grain size evolution with high precision. The mechanisms of austenite grain growth are observed by a confocal laser scanning microscope (VL2000DX) integrated with heating system (SVF17SP) in an in-situ heating experiment. Results indicate that the grain boundary migration is the main mechanism for austenite grain growth of 300M steel.

关键词： grain size evolution grain size distribution grain boundary migration in-situ observation

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Epitaxial growth of copper film by MOCVD 6th

Epitaxial growth of copper film by MOCVD

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6th Annual Meeting on Testing and Evaluation of advanced materials, TEIM 2015

作者： Tu, Rong Huang, Jin Zhang, Song Zhang, Lianmeng State Key Lab. of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology 122 Luoshi Road Wuhan430070 China

ISBN: (纸本)9783038357278

Copper thin films were deposited on single crystal sapphire substrate via metal-organic MOCVD using Cu(acac)2 as precursor. X-ray diffraction (XRD) and Scanning Electronic Microscope (SEM) were employed for studying preferred orientation and microstructure. Atomic Force Microscope was utilized in order to characterize roughness of copper thin layer. By calculation of the Gibbs free energy, the reactions have been deeply understood. Depositions were carried out at various substrate temperatures in the rage 473K to 673K. It has been revealed that temperature determined the orientation and microstructure of copper films. At 673K, copper films have exhibited preferred orientation, smooth surface and connected grains, which proved that this copper thin film can act as precursor. Based on the study of epitaxial growth of copper films, a schematic diagram of epitaxial growth relationship is suggested for the step by step depositions processes. © 2016 Trans Tech Publications, Switzerland.

关键词： Atomic force microscopy

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Effect of Oxygen Partial Pressure on Epitaxial Growth and Properties of Laser-Ablated AZO Thin Films

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Journal of Wuhan University of technology(materials Science) 2016年第1期31卷 27-30页

作者：王传彬 LUO Sijun SHEN Qiang 张联盟 State Key Lab of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China Department of Chemical Engineering and Materials Science University of California Davis CA 95616 USA

Al-doped ZnO（AZO） thin films were grown on c-sapphire substrates by laser ablation under different oxygen partial pressures（P_（O2））.The effect of P_（O2） on the crystal structure,preferred orientation as well as the electrical and optical properties of the films was *** structure characterizations indicated that the as-grown films were single-phased with a wurtzite ZnO structure,showing a significant c-axis *** films were well crystallized and exhibited better crystallinity and denser texture when deposited at higher P_（O2）.At the optimum oxygen partial pressures of 10- 15 Pa,the AZO thin films were epitaxially grown on c-sapphire substrates with the（0001） plane parallel to the substrate surface,i e,the epitaxial relationship was AZO（000 1） // A1_2O_3（000 1）.With increasing P_（O2）,the value of Hall carrier mobility was increased remarkably while that of carrier concentration was decreased slightly,which led to an enhancement in electrical conductivity of the AZO thin *** the films were highly transparent with an optical transmittance higher than 85%.

关键词： AZO thin films epitaxial growth laser ablation oxygen partial pressure electrical and optical properties

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Fast Welding of Chromium Carbide and Nickel Alloy by Spark Plasma Sintering

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Journal of Wuhan University of technology(materials Science) 2016年第4期31卷 835-837页

作者：刘国玺 LI Kezhi LENG Xiaoxuan 张金咏 ZHANG Fan School of Materials Science Northwestern Polytechinical University Xi'an 710072 China Ningbo Branch of Ordnance Science Institute of China Yantai 264003 China China State Key Laboratory of Advanced Technology for Material Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

Spark plasma sintering（SPS） was used to weld the ceramics,eg,Cr3C2 and metal,Ni in this *** is found that the SPS can weld the Cr3C2 and Ni plates at lower temperatures and shorter holding time comparing with that of hot-pressing（HP）.The binding strength was 113 MPa when the temperature was 1000 ℃ by SPS,compared with 10 MPa by HP at the same *** remarkably enhances the atom diffusion in *** analysis at different welding temperatures and holding times of SPS or HP shows that the local temperature gradient,different from the past effects of by-passing current,is the dominative mechanism of the SPS welding.

关键词： Sintering welding Welding holding ceramics sintering welded pressing remarkably heating

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