Hamburg 2001 – wissenschaftliches Programm

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DY: Dynamik und Statistische Physik

DY 20: Ferrofluide I

DY 20.4: Vortrag

Dienstag, 27. März 2001, 10:15–10:30, S 5.5

Succesive separation of ferrofluids for experiments on magnetoviscosity — •Steffen Thurm and Stefan Odenbach — ZARM, Universität Bremen, Am Fallturm, 28359 Bremen

Magnetoviscous effects in commercial ferrofluids are found to be significantly stronger than predicted by theoretical approaches assuming the existence of non-interacting particles. Chain and cluster formation should only take place for relatively large particles or primary agglomerates formed during the production process. Thus a magnetic separation of these particles from the ferrofluid would lead to a quantitative idea of the importance of such large particles for magnetoviscosity in ferrofluids. To get an experimental approach to this problem a high gradient magnetic separation has been established. The separation process is monitored quantitatively to allow its analysis by means of appropriate diffusion theories. Experimental results on the separation process as well as on the magnetoviscous effects for differently purified liquids will be presented.