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Controlling morphology and structure of nanocrystalline cadmium sulfide (CdS) by tailoring solvothermal processing parameters

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JOURNAL OF NANOPARTICLE RESEARCH 2011年第7期13卷 3011-3018页

作者： Dalvand, P. Mohammadi, M. R. Sharif Univ Technol Dept Mat Sci & Engn Tehran Iran

Cadmium sulfide (CdS) with different morphologies was successfully prepared by solvothermal process by controlling the processing parameters, including nature of precursor and solvent, reaction temperature and process time. X-ray diffraction patterns revealed that, in all cases highly pure and crystallized CdS with hexagonal structure were obtained. In addition, it was found that the processing parameters influence on preferable growth direction of CdS nanostructures. Field emission scanning electron microscope analysis showed that CdS nanowires with different aspect ratios were obtained (depending upon the reaction temperature and process time) in presence of sulfur powder and ethylenediamine, whereas CdS nanoparticles were produced by sulfur powder and ethanolamine. Moreover, CdS nanorods were prepared using thiourea and ethylenediamine. Transmission electron microscope image confirmed that CdS nanowire with one of the highest aspect ratio reported in the literature (i.e., 255) was achieved using sulfur powder and ethylenediamine at 200 A degrees C reaction temperature for 72 h process time. UV-Vis absorption spectra of CdS nanostructures prepared under different conditions displayed a blue shift relative to that of bulk CdS due to the quantum size effect.

关键词： CdS Solvothermal processing parameters Characterization Synthesis Quantum effect

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Effect of processing parameters on dimensional accuracy and bending strength of graphite flake/phenolic resin powder mixture in SLS process

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART C-JOURNAL OF MECHANICAL ENGINEERING SCIENCE 2019年第13期233卷 4497-4507页

作者： Wu, Haihua Sun, Yu Peng, Jianhui Huang, Caihua Ye, Xicong China Three Gorges Univ Coll Mech & Power Engn Yichang Hubei Peoples R China

Graphite flake/phenolic resin powder mixture had been prepared via selective laser sintering process. A dimensional analysis involving radial and axial deviation was performed, and the effect of SLS process parameters (laser power, scan spacing, scan speed, layer thickness) in both radial and axial directions were investigated. Laser power is found to be the most significant process variable in radial dimensional accuracy, while in axial direction layer thickness and laser power are the most significant process variable by range analysis based on orthogonal experiment. The optimum combination of parameters in graphite flake/phenolic resin powders mixture SLS process for high dimensional accuracy in radial direction was laser power, scan speed, scan spacing, and layer thickness of 20 W, 1500 m/s, 0.1 mm, and 0.1 mm, respectively, while the optimum combination of parameters in axial direction was laser power, scan speed, scan spacing, and layer thickness of 20 W, 2000 mm/s, 0.1 mm, and 0.15 mm, respectively. Energy density was introduced to better incorporate the processing parameters with dimensional accuracy and mechanical properties, and both dimensional accuracy and bending strength were analyzed under varying energy density and layer thickness, and results showed that in the range of energy density of 0.075-0.15 J/mm(2), layer thickness of 0.1-0.2 mm, a graphite flake/phenolic resin laser sintered part with appropriate bending strength and dimensional accuracy could be prepared.

关键词： SLS processing parameters dimensional accuracy bending strength

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Effects of trace amount modified SiC nanoparticles and processing parameters on microstructure and mechanical properties of ZA27 alloy

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INTERNATIONAL JOURNAL OF CAST METALS RESEARCH 2024年第1期37卷 39-47页

作者： Yan, Zhiming Wang, Huicong Zhong, Yuan Liu, Guilin Zou, Cunlei Teng, Yingli Dalian Jiaotong Univ Sch Mat Sci & Engn Dalian Peoples R China

In order to strengthen and obtain the optimised processing parameters during the modified SiC nanoparticles reinforce ZA27 alloys. The present investigation deals with the effects of trace amount modified SiC nanoparticles and processing parameters on the microstructures and mechanical properties of ZA27 alloy. The results indicate that the microstructures are effectively refined by the modified SiC nanoparticles. It's likely to fade the refined effect for the modified SiC nanoparticles to raise the addition temperature, prolong the holding time, increase the pouring temperature and enhance the cooling rate. In this experiment, when the addition amount is 0.5%, the addition temperature is 680 degrees C, the holding time is 3 min, the pouring temperature is 600 degrees C and the mould is preheated at 200 degrees C, the microstructure and mechanical properties of ZA27 alloy are better. The action mechanisms of the modified SiC nanoparticles and processing parameters are also discussed.

关键词： ZA27 alloy microstructure modified SiC nanoparticles processing parameters mechanical properties

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Effects of processing parameters on the temperature field of selective laser melting metal powder

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POWDER METALLURGY AND METAL CERAMICS 2009年第3-4期48卷 186-195页

作者： Li, Ruidi Shi, Yusheng Liu, Jinhui Yao, Huashan Zhang, Wenxian Huazhong Univ Sci & Technol State Key Lab Mat Proc & Die & Mould Technol Wuhan 430074 Peoples R China

Based on temperature-dependent thermophysical parameters and nonlinear phase transformation from powder to liquid, a three-dimensional transient thermal finite model of selective laser melting process is developed. Commercial ANSYS software is used to simulate the distribution of the temperature field in selective laser melting. The simulation results show that a lower scan speed, higher laser power, and a lower scan interval enable much higher maximum temperature in the powder bed and wider scan track width. The scan modes also have great influence on the temperature field. Temperature in the powder bed experiences fluctuant variation with transverse scan mode in contrast with moderate variation with lengthwise scan mode. The simulated results are compared with the experimental results and good agreement is found in scan track width.

关键词： selective laser melting 316L stainless steel powder temperature field numerical simulation processing parameters

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Optimization of processing parameters in fiber laser cladding

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INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY 2020年第9-10期111卷 2553-2568页

作者： Mohammed, Sayeed Zhang, Zhe Kovacevic, Radovan Southern Methodist Univ Res Ctr Adv Mfg RCM Dept Mech Engn Dallas TX 75205 USA

Laser cladding of steel is a promising solution to wear and corrosion resistance, and to the improvement of the mechanical properties of the cladded surface. The properties of cladded components depended on the clad geometry. The clad geometry was governed by the processing parameters. In this study, a cored wire with a sheath made of 95 wt% Co and 5 wt% Fe, with an outer diameter of 1.2 mm and an inner diameter of 0.8 mm, was used. A full factorial design was used to optimize the processing parameters in cored wire laser cladding. The design consisted of three main factors: laser power, scanning speed, and cored wire feed rate, each at three levels in addition to the current, laser spot diameter, and stand-off distance. The response functions were clad width, height, aspect ratio (width/height), dilution ratio (penetration area/total fusion area), and the hardness. The mathematical relationships were established by statistical analysis. The optimal values of the parameters were determined from these relationships. The overlay plots were made from graphical optimization to serve as a technical reference for operators in the workshop for laser cladding with a specific material of cored wire. It was found that a laser power of 3.7 to 3.9 kW, a cored wire feed rate of 75 mm/s, and a scanning speed close to 6 mm/s were the optimal values.

关键词： processing parameters Cored wire Cladding Steel

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The influences of processing parameters on forming characterizations during laser rapid forming

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MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND processing 2003年第1-2期360卷 18-25页

作者： Li, YM Yang, H Lin, X Huang, WD Li, JG Zhou, YH Shanghai Jiao Tong Univ Sch Mat Sci & Engn Shanghai 200030 Peoples R China Northwestern Polytech Univ State Key Lab Solidificat Proc Xian 710072 Peoples R China

Laser rapid forming experiments were carried out with 316L stainless steel and nickel-base alloy to investigate the influences of the processing parameters on forming characterizations systematically. It is found that the height of a single cladding layer was very important for fabrication accuracy and forming stability of components of laser rapid forming because it was affected by almost all processing parameters and was quite difficult to precisely control. For the system with lateral powder feeding pattern, the powder injection point was the most important factor to the height control of single layer. The variation of the width of single clad, which was mainly affected by laser power, spot diameter and scanning velocity, was similar to that in laser surface melting. The surface quality was another important characterization for laser rapid forming and was remarkably affected by oxidation and the powder adhesion. In order to improve the surface quality, the flow flux of shielding gas should be not less than 10 1 min(-1) and the powder stream cannot be injected to the tail part of the melt pool. Based on the investigation, some metal components were fabricated. (C) 2003 Elsevier B.V. All rights reserved.

关键词： laser rapid forming processing parameters forming characterizations metal components

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Optimization of processing parameters for Laser Powder Deposition using Finite Element Method

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Journal of Wuhan University of Technology(Materials Science) 2010年第5期25卷 832-837页

作者：付垚 State Key Laboratory of Non-ferrous Metals and Processes General Research Institute for Non-ferrous Metals

In order to investigate the effects of powder materials and processing parameters on thermal and stress field during laser powder deposition （LPD）, a finite element model was developed with the help of ANSYS software. The finite element model was verified by the comparison between the experimental results and computed results. Then LPD processes with different powder materials and processing parameters were simulated by using the FE model. The results show that less difference of thermal conductivity and thermal expansion coefficient between powder material and substrate material produces lower residual stress; higher laser power, laser scanning speed and smaller laser beam diameter can lead higher peak temperature and higher residual stress. The research opens up a way to rational selection of the powder materials and processing parameters for ensured quality.

关键词： laser powder deposition thermal field stress field powder material processing parameters

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Influence of processing parameters and heat treatment on phase composition and microstructure of plasma sprayed hydroxyapatite coatings

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Transactions of Nonferrous Metals Society of China 2009年第S02期19卷 463-469页

作者： ZHAO Guo-liang WEN Guang-wu WU Kun School of Materials Science and Engineering Harbin Institute of Technology(Weihai)Weihai 264209China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China

Air plasma spraying process was employed to fabricate various hydroxyapatite(HA)coatings on titanium *** influence of processing parameters on the phase composition and the microstructure of the obtained coatings was *** effect of heat treatment on as-sprayed coating in terms of the crystallinity and microstructure was also *** phase composition of coatings was analyzed by X-ray diffraction(XRD)and *** surface and cross-section morphologies and microstructure of coatings as well as the morphology of feedstock were evaluated using scanning electron microscope(SEM).The crystallization temperature of amorphous HA phase in as-sprayed coating was examined by using differential thermal analysis(DTA). The results suggest that phase composition and microstructure of as-sprayed HA coatings strongly depend on the spraying parameters,and heat treatment at 760 ℃for 2 h is one of effective means for increasing the crystallinity and improvement in microstructure of as-sprayed HA coatings.

关键词： hydroxyapatite coatings plasma spraying processing parameters heat treatment

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Influence of processing parameters on the phase composition of ZrN-Si_3N_4 synthesized from zircon

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Rare Metals 2009年第4期28卷 367-371页

作者： MA Beiyue YU Jingkun School of Materials and Metallurgy Northeastern University Shenyang 110004 China

The optimum parameters were determined for synthesizing ZrN-Si3N4 composite powder from zircon by carbothermal reduction-nitridation （CTRN） process. The samples were prepared by mixing the carbon black of an average particle size less than 30 μm and the zircon of 40 μm with C/ZrSiO4 mass ratios of 0.2, 0.3, 0.4, and 0.5. The prepared samples were subjected to the CTRN process at temperatures of 1673, 1723, 1753, and 1773 K for 6, 9, and 12 h. The CTRN process was conducted in an atmosphere-controlled tubular furnace in a nitrogen gas flow of 1.0 L/rain. All the products were examined by X-ray powder diffraction to determine the transformation. The results showed that the proper transformation of ZrN-Si3N4 occurred at 1773 K for 12 h with a C/ZrSiO4 mass ratio of 0.4.

关键词： inorganic non-metal materials nitrides carbothermal reduction-nitridation zircon processing parameters phase composition

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A design framework for optimizing forming processing parameters based on matrix cellular automaton and neural network-based model predictive control methods

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APPLIED MATHEMATICAL MODELLING 2019年 76卷 918-937页

作者： Chen, Dong-Dong Lin, Y. C. Wu, Fan Cent S Univ Sch Mech & Elect Engn Changsha 410083 Hunan Peoples R China State Key Lab High Performance Complex Mfg Changsha 410083 Hunan Peoples R China

The advanced modelling/simulating method and the effective optimization/controlling strategy relying on knowledge-based systems are highly demanded in industrial manufacturing of alloy components. In this work, based on the advantages of cellular automaton (CA) simulation and neural network-based model predictive control (NNMPC) methods, a material design framework is developed to optimize processing parameters for the designed target microstructures of alloys. In this framework, a matrix CA simulation method is developed to accurately and quickly describe the variations of microstructures with processing parameters. NNMPC, which is an effective control method for nonlinear and multi objective system, is utilized to online optimize processing parameters according to the designed target microstructures. Based on the optimized processing parameters, the hot compressive deformation tests of a Ni-based superalloy are conducted to verify the effectiveness of the developed framework. The experimental results well agree with the simulated/designed ones, which implies that the developed material design framework can effectively optimize processing parameters for the designed target microstructures. Also, the developed material design framework is used to obtain the uniform and fine microstructures of a Ni-based superalloy. (C) 2019 Elsevier Inc. All rights reserved.

关键词： Design framework Cellular automaton simulation Neural network-based model predictive control method processing parameters

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