Papers by Keyword: Spray Forming

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Authors: Ying Dong Qu, Xiao Hong Li, Chong Jiang, Rui Ming Su, Rong De Li
Abstract: In order to improve the atomization quality of spray forming, the cylindrical hollow jet technology was applied in the atomization process of spray forming, and a numerical simulation for the structure of hollow flow field in front of jet outlet was carried out, the distribution of hollow jet flow field was simulated under different inlet velocities and outflow technologies, and then the experimental verification was performed. The simulation results of single-phase flow field show that with increasing the liquid inlet velocity, the back flow are a can get enlarged, and the lower negative pressure can be generated, which is beneficial for the out flow of liquid metal. The simulation results of two-phase flow field show that the hollow jet can be produced a hollow part. The conclusion basically accords with the experimental result of water flow.
Authors: F. Saporiti, A.H. Kasama, B. Arcondo, Walter José Botta Filho, Claudio Shyinti Kiminami, Claudemiro Bolfarini, Fernando Audebert
Abstract: Fe-Si alloys have excellent soft magnetic properties, specially around 12 at% Si. However, its industrial application is limited because of the lack of ductility, which causes cracking during rolling operations for the fabrication of thin sheets. The reason of the brittleness of the high silicon alloys is a disorder/order reaction at low temperatures. The aim of this work is to analyze the effect of the addition of Aluminum on the crystalline structure of Fe-Si alloys. Samples with a chemical composition of Fe88Si12 and Fe87Si12Al1 (at%) were prepared by Spray Forming. The structure was studied by means of X-ray diffraction and Mössbauer Spectroscopy. The presence of the DO3 and α- Fe phases were observed
Authors: Yong Bing Li, Hua Cui, Jin Feng Huang, Yuan Hua Cai, Zi Han Wang, Ji Shan Zhang
Abstract: In this study, cylindrical billets of Mg-3Al-1Zn (AZ31) alloy have been synthesized by spray forming technique. The alloy billets were hot-extruded into rods with proper processing parameters. The microstructures and mechanical properties of alloys were investigated. The results indicated that spray formed AZ31 alloys have a homogeneous and equiaxial grains with average grain size of 20μm. The further grain refinement with an average grain size of 5μm was attributed to the continuous dynamic recrystallization during the extrusion processing. The room temperature mechanical properties of the extruded rods are remarkably higher than those of as-cast AZ31 alloy. The average tensile ultimate and yield strength of the alloy are 321MPa and 237MPa, respectively, with an elongation of 15.2%.
Authors: Y.P. Hung, K.J. Wu, Chi Y.A. Tsao, J.C. Huang, P.L. Hsieh, Jason S.C. Jang
Abstract: The current study applies the inclusion of thermally stable ceramic nano powders into the light weight AZ61 Mg base alloys via spray forming plus extrusion. The combination of spray forming and severe extrusion provides a new processing route for fabricating nano composites, with uniform distribution of the nano fillers. Parallel tries using the PM route followed by the same severe extrusion can also yield sound composites but the dispersion of the nano SiO2 appears to be less uniform. The processed composites are characterized in terms of microstructure examination, thermal analysis, phase identification, and mechanical testing.
Authors: Shih Han Wang, Chi Y.A. Tsao
Abstract: Magnesium materials are gaining an increasing interest especially in transportation industries. The goals are the reduction of fuel and the reduction of the green house gas CO2. To achieve these goals, the weight of vehicles must be reduced. Compared to Al based materials, Mg based materials offer the possibility of saving up to 30% in weight. Unfortunately the latter suffer from poor workability. The workability of AZ91B has been proven to be improved significantly by employing the rapid solidification process, Spray Forming. In this study, the AZ80 Mg alloy was synthesized via Spray Forming process. The microstructures were characterized and compared with conventionally cast materials. The workability of the spray-formed AZ80 Mg alloys was studies via a simple extrusion process. The effects of the extrusion speed and temperature on the workability were investigated.
Authors: Claudio Shyinti Kiminami, N.D. Bassim, Michael J. Kaufman, M.F. Amateau, T.J. Eden, J.M. Galbraith
Authors: C. Triveño Rios, Conrado R. M. Afonso, Claudemiro Bolfarini, Walter José Botta Filho, Claudio Shyinti Kiminami
Abstract: Bulk glassy alloys based on the Fe-Co-B-Si-Nb system have already achieved high levels of mechanical strength. The present work investigated the microstructural evolution of Fe43.2Co28.8B19.2Si4.8Nb4 alloy during the spray forming and wedge mold casting processes, with emphasis on the formation of amorphous phase. The microstructure was evaluated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). The region outer the spray deposit showed the formation of an amorphous structure with a thickness of ~2.5 mm, while that of the wedge-shaped sample exhibited a thickness of up to ~1.5 mm, suggesting that both processes show a promising potential for the production of bulk glass alloys.
Authors: C.H. Chiang, Chi Y.A. Tsao
Abstract: The coarsening behavior of spray-formed A-35wt%Si and A-45wt%Si alloys in the semisolid state were studied. The coarsening kinetic and Si size distributions after coarsening at various temperatures and times in the semi-solid state were investigated. The coarsening exponents, n, the rate constants, K, in the LSW theory, and the modified rate constants were determined from previous works. The coarsening activation energies of the two spray-formed alloys were calculated from the slopes of ln(KT) vs. 1/T plots. The Si size distribution functions after holding at various temperatures and times in the semisolid state were determined for the two spray-formed alloys. The effects of the stokes-motion in addition to pure diffusion mechanism on the variations of coarsened Si size distribution were also investigated.
Authors: Muh Ron Wang, Pin Jen Chen, Je Rei Yang, Jin Shen Chiu, Tien Chu Lin, Teng Sun Lai
Abstract: This paper describes the performance of an atomizer coupled with a substrate which produces metal powder and spray forming materials simultaneous in the spray chamber. Ultra fine metal powders are produced from this process. The melt is atomized by a twin-fluid atomizer with internal mixing mechanisms. The molten spray injected from the swirling chamber of the atomizer is then impinged upon the substrate to form the two phase impinging flow. The deposition rate of the molten spray on the substrate is controlled by the diameter of the substrate, the height of the substrate ring and the distance of the substrate from the outlet of the atomizer. This in turn determines the powder production rate of the spraying processes. Experimental results indicate that the deposition rate of the spray forming material decreases as the distance between the substrate and the atomizer increases. For example, the deposition rate decreases from 48% to 19% as the substrate is placed at a distance from 20cm to 40cm. On the other hand, the metal powder production rate and its particle size increases as the substrate is placed far away from the atomizer. The production of metal powder with mean particle size as low as 3μ m level has been achieved, a level which is not achievable by the conventional gas atomization processes.
Authors: Yue Wang, Zhou Li, Wen Yong Xu, Hua Yuan, Na Liu, Zheng Jiang Gao, Shi Fan Tian, Guo Qing Zhang
Abstract: The hot deformation behaviors of spray formed superalloy GH738 were investigated by using of Gleeble-3500 simulator in the temperature range of 950~1200, with a strain rate of 0.13~6.5s-1 and reduction of 50%. The corresponding flow curves were determined and hot deformed microstructures were observed. The results showed that the flow stress decreased with increasing deformation temperature or decreasing strain rate. A full dynamic recrystallization microstructures with fine-equiaxed grains were obtained at the temperature of 1100~1150 and strain rate of 2.6~6.5s-1. The hot deformation activation energy Q was 580.81kJ.mol-1, and the constitutive equation was derived by means of linear regression.
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