From: monwel@cbnewsk.cb.att.com (douglas.w.monroe)
Newsgroups: sci.materials,sci.engr
Subject: SUMMARY: Electro-Rheology materials
Keywords: NCSU, Dr. Conrad
Date: 13 Apr 92 16:29:42 GMT
Followup-To: poster
Distribution: usa
Organization: AT&T


A week or so ago I posted a request for info regarding
electro-rheological materials. Below is my original posting and the
collection of responses. Thanks to *all* who responded! There
seemed to be sufficient interest from other wanting info to warrant
this summary. Hope it helps someone.

Original Posting:

 Hi there! A long time back, I recall reading about a material(s?) 
which change from solid to liquid-like upon application of voltage. 
I believe this was used in a clutch or braking application. If I 
remember correctly, the material was refered to as an electro-
rheological fluid. Anyone have any details about these materials and 
whether they are commercially available? Please e-mail,
 I'll sumarize if there's enough interest.



Responses follow:

From: boland@cps.msu.edu

 
There was a Prof. Filisko at the UM-Ann Arbor who patented what you are
referring to (I think).  This must have been 5 years ago or so... One
of the automakers were looking into applications I think.  I'm sure
you could do a journal search...  Hope this helps...
 
jb
*************************************************************

From: jrtyner@eos.ncsu.edu


   Our Dr. Conrad and some students and co-workers have been working on ER
fluids.  I don't know details, but he may be reached at 
      
      NCSU
      Dept. of Materials Science and Engineering
      Box 7907
      Raleigh, NC  27695-7907

      (919) 515-2377  			


John
**************************************************************

From: J. A. Sarreal <sarreal@mcnc.org>

I believe the pioneer for this type of material is Dr. Conrad
at NCSU.  You may want to correspond with him about this.

The Dept. of Mat. Sci. and Eng. #: 919-737-2377

GOOD LUCK!    
************************************************************

From: hiro@ccwf.cc.utexas.edu (Hiro)

ER fluids consist of two mail ingredients: the base liquid and the
suspended particles. The base liquid must be a good electrical insulator
and strongly hydrophobic. The spherical particles (zeolites), ranging from
submicron to several microns in diameter is porous and make up 15-40% of
the liquid. The physical reason for the properties of ER fluids is not
well understood, but apparently, the absorption/desorption of the liquid
into/out of the zeolite is a key factor.

I did a senior project on designing a brake using ER fluid 3yrs ago, and I
have the following references:

1. W. M. Winslow, J. Appl. Phys. vol. 20, (1949).
2. J. E. Strangroom, Phys. Technol, vol. 14 6(1983).
3. F. Zukoski, and J. W. Goodwin, Proc. IECON 1986 Industrial Application of 
   Mini, Micro & Personal computers, vol. 1 (1986).
4. Engineering vol.228, pp.i-iv (1988).
5. A. F. Sprecher, J. d. Carson, and H. Conrad, Mat. Sci. and Eng. vol. 95 
   (1987).
6. N. G. Stevens, J. L. Sproston and R. Stanway, J. Electrostatics, vol. 17 
   (1985).

I wrote the paper in 1989, so are probably more recent papers. Also, there
is extensive research being done in England. The following companies have ER 
fluids for sale:

ER Fluid Developments, London
British Technology Group
Castrol Corp.
Lord Corp, North Carolina

I hope the above information will get you started. Also, I would be very 
interested in learning about your research and application of ER fluids.

Hiro Kinoshita
----------------------------------------------------------------------------
hiro@ccwf.cc.utexas.edu
Microelectronics Research Center
Department of Electrical and Computer Engineering
The University of Texas at Austin
Austin, TX 

*****************************************************************

From: Joe Rosato <jarj_ss@uhura.cc.rochester.edu>

Here are some references on Electrorheological Fluids.
Hope they help.

Klass Donald L. & Martinek, Thomas W., 1967
"Electroviscous Fluids. I. & II Rheological Properties"
Journal of Applied Physics, 38(1) p.67-80

Stevens, N.G., Sproston, J.L., Stanway, R., 1985
"The Influence of Pulsed D.C. Input signals on Electrorheological fluids"
Journal of Electrostatics, 17 p.181-191

Stevens, N.G., Sproston, J.L., Stanway, R., June 1988
"An Experimental Study of Electrorheological Torque Transmission"
Journal of Mechanisms, Transmissions, and Automation in Design, 110 p.182-188

Pool, Robert, March 1990
"The Fluids with a case of Split Personality"
Science 24 p.1180-1181

Webb, Nigel, April 1990
"Electrorheological fluids"
Chemestry in Britain, p.338-340

Goldstein, Gina, Oct 1990
"Electrorheological fluids: Applications begin to gel"
Mechanical Engineering  p.48-52

					
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From: routd@woods.ulowell.edu

hi doug,
this is interesting! I want to know more about them. I can guess something
like this: if a polymer is having anisotropy, or liquid crystallinity, say, lcp
like vectra and kevlar. one can orient the molecules(again assuming that there is a substantial dipole moment associated) in e-field and thus changing the tensile strength drastically( tensile strength is also anisotropic)
Thanks and hope to hear from u soon!
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-- 
******************************************************************************
                                                          Doug Monroe
                   				       dwm@pruxl.att.com
  						 -or-  monwel@cbnewsk.att.com
Newsgroups: sci.materials