Physic Simulation of Slurry Preparation by Ultrasonic Vibration in Semisolid Metal Processing

Abstract:

In current research, a series of visualization experiments simulating the action of ultrasonic vibration (UV) in metal slurry preparation process on fluid flow, grain nucleation and growth as well as its interaction with viscosity of fluids were conducted. In these visualization experiments, the metal slurry maker was substituted by a transparent cup while the liquid and semisolid slurry of metal were replaced by other fluids or mixture system with similar characteristics. Scaled-up UV was applied to the liquid or mixture systems. The simulation shows that UV can roll up the particles at the bottom of the cup and make the liquid convection intense below the radiating surface of sonotrode while weak above it. UV can break dendrites rapidly and distribute them in melt. High viscosity reduces the actual power transmitted into liquid, and higher viscosity requires higher inception power of UV.

• Periodical: Materials Science Forum (Volumes 704-705)
• Pages: 1279-1283
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.704-705.1279
• Online since: December 2011
• Authors: Jun Wen Zhao, Shu Sen Wu, Guang Ze Dai, Jing Han, Xing Min Huang
• Keywords: Semisolid Metal, Simulation, Slurry, Ultrasonic Vibration (UV)

References

[13] J. S. Xie: Glycerol (Light industry press, Beijing 1984). (in Chinese) ]. Table 1 Actual input power of UV at 10℃ in glycerol-H2O systems (preset power: 1200W) glycerol(wt. ％) 0 30 50 60 70 75 Corresponding viscosity(mPa·s).

[1] 308.

[3] 49.

[9] 01.

[17] 4.

[38] 8.

[65] 2 Actual input power(W) 1200 1040 800 720 640 480 The Actual input power at 10℃ in different content glycerol systems is list in Table 1. As the glycerol content increases from 0 to 75%, the viscosity increases from 1. 308mPa·s to 65. 2mPa·s. when the glycerol content reaches 75%, UV would terminate occasionally. When the glycerol content greater than 75% or temperature of 75% glycerol system is below 10℃, UV could not be started. When the viscosity of glycerol-H2O systems system is high, weak UV will occur, and a few minutes of UV are needed to stabilize the actual input power. The weak UV can be perceived by touching the surface of the sonotrode with fingers, it gives a significant different feeling with that of normal UV. Fig. 7 Actual input power vs viscosity in glycerol-H2O system For a certain system, the viscosity can be controlled by adjusting its temperature, and rise of temperature will lower the viscosity rapidly. Fig. 7 illustrates that the actual input power decreases linearly with viscosity both in pure glycerol and 95% glycerol system. While UV gets bigger power in 95% glycerol system than in pure glycerol system under the same viscosity. Through above analysis, the actual input power reduces with increase of viscosity and it is different for different glycerol-H2O systems even with the same viscosity. Experiments indicate that viscosity of normal UV is 65mPa·s in water, 32 mPa·s in pure glycerol system and 500 mPa·s in 95% glycerol system, respectively, demonstrating that inception and intensity of UV is related to properties of materials imposed. Summary.

[1] Acoustic streaming induced by UV will roll up the particles at the bottom of cup and make the liquid convection intense below the radiating surface of sonotrode while weak above it.

[2] UV can break dendrites rapidly and distribute them in melt. No dendrites will appear if UV is imposed during solidification process.

[3] High viscosity reduces the actual power transmitted into liquid, and higher viscosity requires higher inception power of UV. Acknowledgements This work was funded by Project(SWJTU09BR149) supported by the Fundamental Research Funds for Central Universities, China and Project(2009Q003) supported by Southwest Jiaotong University, China. References.