The Experts below are selected from a list of 63 Experts worldwide ranked by ideXlab platform
Yuyuan Zhao - One of the best experts on this subject based on the ideXlab platform.
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Particle size distribution of tin powder produced by Centrifugal Atomisation using rotating cups
Powder Technology, 2017Co-Authors: L.p. Zhang, Yuyuan ZhaoAbstract:Abstract Centrifugal Atomisation is a low-cost technology for producing metal powders, but its wide applications are hampered by its limited capability of producing fine powders and there is insufficient research on the particle size distributions of Centrifugally produced powders. This paper studies the effects of the atomiser geometry and the key process parameters on the particle size distribution of tin powders produced by Centrifugal Atomisation. The results showed that the particle sizes of the as-produced powders follow lognormal distribution. The median particle size for all atomisers decreases with increasing atomiser rotation speed and with decreasing melt flow rate, due to reduced film thickness of the melt before disintegration. The cup atomiser with a wall angle of 67.5° produced the finest powders, because of a significant improvement of dynamic wetting between the melt and the atomiser. The particle size distributions of all the powder samples have a similar lognormal bell shape with the geometric standard deviations between 1.6 and 2.5. Narrow particle size distributions can be achieved by reducing the variability of any of the processing parameters affecting the particle size.
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Considerations in designing a Centrifugal atomiser for metal powder production
Materials & Design, 2006Co-Authors: Yuyuan ZhaoAbstract:Abstract In Centrifugal Atomisation for metal powder production, the key to the control of the particle sizes is the design of the atomiser. This paper studies the main issues concerned in designing a Centrifugal atomiser and provides guidance on the selection of an electric motor, radius of atomiser, slope angle of atomiser wall and flow rate of cooling water. In the selection of the atomiser radius, the power and material constraints as well as the hydraulic jump radius need to be considered. A cup atomiser with a slope angle of 60–70° would result in small spray droplets and thus a fine powder. The water cooling system needs to be assessed by examining the heat flow in the solid metal layer and in the atomiser.
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A Simplified Model for Velocity and Temperature Evolution of Alloy Droplets in Centrifugal Atomisation and Spray Deposition
Materials Science Forum, 2005Co-Authors: Yuyuan ZhaoAbstract:A model has been developed for the velocity and temperature evolution of a metal alloy droplet with travel distance in Centrifugal Atomisation. The droplet velocity decreases rapidly with increasing travel distance. The degree of droplet cooling at a certain travel distance decreases with increasing droplet velocity, increasing diameter and decreasing temperature, and is also affected by the droplet physical properties. The solidification of the droplets is largely dependent upon the latent heat removal.
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Modelling thermal development of liquid metal flow on rotating disc in Centrifugal Atomisation
Materials Science and Engineering: A, 2004Co-Authors: Yuyuan ZhaoAbstract:In Centrifugal Atomisation the formation of a solid skull on the atomising disc is a major problem, which has adverse effects on the quality and quantity of the as-produced powder and also on the balance of the disc during Atomisation. It is costly and difficult to study the flow behaviour because of the complex interaction between the liquid metal and the atomising disc. A computational fluid dynamics model has been developed using Flow-3D to simulate the thermal development of the liquid metal on the atomising disc. Under a fixed process condition, the liquid metal has a nearly constant solidification rate before the steady state is achieved and a solid skull is formed gradually. The volume of the skull decreases with increasing liquid metal flow rate, initial disc temperature and initial liquid temperature.
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Effects of processing conditions on powder particle size and morphology in Centrifugal Atomisation of tin
Powder Metallurgy, 2004Co-Authors: J.w. Xie, Yuyuan Zhao, J J DunkleyAbstract:This paper investigates the effects of atomiser design and processing parameters on the morphology and size distribution of Centrifugally atomised tin powder. Premature solidification of the melt on the atomiser and poor wetting of the atomiser by the melt were found to be the main causes of unsuccessful Atomisation. The particle size distributions of the powders follow a lognormal distribution. The median particle size increased with decreasing atomiser rotation speed and with increasing melt flowrate. Cups with a high included angle made significantly finer powders than flat discs under the same operating conditions.
Xucheng Deng - One of the best experts on this subject based on the ideXlab platform.
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Prediction of powder particle size during Centrifugal Atomisation using a rotating disk
Science and Technology of Advanced Materials, 2007Co-Authors: Xucheng DengAbstract:The Centrifugal Atomisation of metallic melts using a rotating disk is an important process for powder production and spray deposition. The theoretical prediction of powder particle size is desirable for the design of atomisers. In this paper, wave theory was applied to analyse the disintegration of metallic melts in the film disintegration regime during Centrifugal Atomisation using a rotating disk. A mathematical model was proposed to predict the spray parameters. The governing equation for the fastest-growing wave number was developed and solved numerically. The effect of the variation in film thickness during film extension was taken into account. Film length and powder particle size were calculated and compared with available experimental data in the literature, and a good agreement was achieved. The influence of the break-up parameter was studied, and it is shown that the break-up parameter is not sensitive to the predicted powder particle size. Both simulated results and experimental data showed that fine powders can be produced by increasing disk speed.
M. Torralba - One of the best experts on this subject based on the ideXlab platform.
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Microstructure and thermal stability of Al–Cr–X (X=Ni, Mo, Si) powders obtained by Centrifugal Atomisation
Materials Science and Technology, 1996Co-Authors: B. Sánchez, A. García-escorial, M. C. Cristina, G. Caruana, M. TorralbaAbstract:AbstractThe microstructure and the thermal stability of rapid solidified Centrifugally atomised AI–3Cr–X (X=1Ni, 3Ni, 0·3Mo, 1Si, or 3Si, at.-%) powders were studied. Three main types of microstructure were observed in the powders: cellular, globular, and rosettelike. Some powders exhibited a mixture of these. In the atomised state the alloys usually had two phases, intermetallic Al13Cr2 and α-Al solid solution. Thermal stability was studied for a range of temperatures from 20 to 500°C. The phase Al3Ni appeared in the nickel containing alloys and grew upon heat treatment. The molybdenum containing alloy did not show any noticeable change upon heat treatment. With respect to the silicon containing alloys, the intermetallic Al13Cr2 transformed into Al13Cr4Si4 at high temperatures. On the basis of bibliographic information a nucleation map was calculated relating the prevalence of the intermetallic Al13Cr2 phase and the α-Al phase to the particle diameter and the chromium concentration of powder obtained by ...
Huajiang Ouyang - One of the best experts on this subject based on the ideXlab platform.
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Vibration analysis of atomising discs
Journal of Physics: Conference Series, 2009Co-Authors: Huaxia Deng, Huajiang OuyangAbstract:The Centrifugal Atomisation of metallic melts using a spinning disc is an important process for powder production and spray deposition. In the manufacturing process the high-temperature melt flows down to the surface of the atomising disc spinning at very high speed. It is observed that there is a hydraulic jump of the melt flow prior to Atomisation. In this paper, the dynamic model of the atomising disc as a spinning Kirchhoff plate with this hydraulic jump is established. The flowing melt is modelled as moving mass and weight force in the radial direction. Using a Galerkin method, it is found that the vibration properties of the atomising disc vary with the disc clamping ratio. The amplitude of the vibration is largely raised when the clamping ratio is smaller than the critical jump radius ratio. It is also found that the disc vibration is non-stationary before becoming steady and the amplitude decreases with increasing disc speed.
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Vibration of an atomising disc subjected to a growing distributed mass
Journal of the Mechanics and Physics of Solids, 2005Co-Authors: Huajiang OuyangAbstract:Centrifugal Atomisation using a spinning disc is an effective means of producing high quality metal powder. The atomising disc frequently experiences severe vibration and produces noise. The vibration adversely affects the production of metal powder. This paper presents the first study of the dynamics of atomising discs. The disc is modelled as a plate under the excitation of a growing mass, which represents the metal stream flowing down to and spreading out on the disc. The influence of the rotating speed of the disc and the growing mass on the dynamics of the disc is investigated. It is found that the disc vibration is non-stationary with multiple frequencies that vary with time and its magnitude increases with mass flow rate of the model metal and decreases with the disc speed. One interesting finding is that the disc vibration grows like flutter in the period before the metal flow on the disc becomes steady, due to the radially growing mass.
L.p. Zhang - One of the best experts on this subject based on the ideXlab platform.
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Particle size distribution of tin powder produced by Centrifugal Atomisation using rotating cups
Powder Technology, 2017Co-Authors: L.p. Zhang, Yuyuan ZhaoAbstract:Abstract Centrifugal Atomisation is a low-cost technology for producing metal powders, but its wide applications are hampered by its limited capability of producing fine powders and there is insufficient research on the particle size distributions of Centrifugally produced powders. This paper studies the effects of the atomiser geometry and the key process parameters on the particle size distribution of tin powders produced by Centrifugal Atomisation. The results showed that the particle sizes of the as-produced powders follow lognormal distribution. The median particle size for all atomisers decreases with increasing atomiser rotation speed and with decreasing melt flow rate, due to reduced film thickness of the melt before disintegration. The cup atomiser with a wall angle of 67.5° produced the finest powders, because of a significant improvement of dynamic wetting between the melt and the atomiser. The particle size distributions of all the powder samples have a similar lognormal bell shape with the geometric standard deviations between 1.6 and 2.5. Narrow particle size distributions can be achieved by reducing the variability of any of the processing parameters affecting the particle size.