Measurement of Density of Fe-Co Alloys Using Electrostatic Levitation
- PDF / 855,739 Bytes
- 6 Pages / 593.972 x 792 pts Page_size
- 79 Downloads / 184 Views
TRODUCTION
THE processing of metals and alloys frequently involves melting and solidification. The first step to understand and control these processes is to accurately measure material properties for metals and alloys in their liquid state. For example, accurate prediction of convection and heat transfer during a casting process is often of critical importance in order to control a casting process and to improve the quality of cast products. The accurate prediction of dynamic events which occur during liquid metal processing is a challenging task due to some technical difficulties encountered at high temperatures. Simulations using either analytical or numerical approaches require accurate material properties of liquid metals, such as density, viscosity, and surface tension. The availability of accurate density data is crucial as it must be known in order to simplify the procedures needed to measure both viscosity and surface tension. Therefore, there have been a number of efforts to increase the accuracy and precision of density measurements over a wide range of temperatures. Several traditional techniques for the density measurement include dilatometric,[1,2] pycnometric,[3] aerometric,[4] radiographic,[5] Archimedean,[6] maximum bubble pressure (MBP),[7,8] and liquid drop[9] methods. The accuracy and applicability of these methods is limited due to the chemical instability of specimens and test apparatus. JONGHYUN LEE, Research Assistant Professor, and ROBERT W. HYERS, Professor, are with the Mechanical and Industrial Engineering Department, University of Massachusetts, 160 Governors Drive, Amherst, MA 01003. JUSTIN E. RODRIGUEZ, Research Associate, and DOUGLAS M. MATSON, Associate Professor, are with the Mechanical Engineering Department, Tufts University, 200 College Avenue, Medford, MA 02155. Contact e-mail: douglas. [email protected] Manuscript submitted May 9, 2014. Article published online August 14, 2015. 2470—VOLUME 46B, DECEMBER 2015
In recent decades, containerless processing has emerged as an effective tool for measuring thermophysical properties of molten metals at high temperatures. By innovatively removing containers, containerless processing essentially eliminates the potential for chemical reaction between the specimen and testing apparatus. The advantages of containerless processing compared to the conventional methods are the lower risk of sample contamination, the wider range of processing temperatures, and the accessibility to metastable states and phases. There are two widely used non-contact methods: electromagnetic levitation (EML) and electrostatic (ESL) levitation. EML removes the necessity of a container by floating a conductive sample of 5 to 8 mm diameter using Lorentz forces generated by alternating currents running through water-cooled copper tube coils. The upper and lower parts of the coil are counter-wound to generate a quadrupole electromagnetic field in which the sample is stabilized. Normally, the lower EML coils must have more turns to generate upward resultant forces equivalent to t
Data Loading...
