Electrorheology

Magnetorheological materials (fluids) are the magnetic equivalent of electrorheological fluids. In this case, the particles are either ferromagnetic or ferrimagnetic sohds that are either dispersed or suspended within a Hquid and the apphed field is magnetic (14). 

Electrorheological Fluids. Electrorheological fluids are a newer category of hydrauhc fluids being actively pursued for use in shock absorbers. An electric field causes the fluid to thicken. 

Many investigators beheve that the Bingham model accounts best for observations of electrorheological behavior (116,118), but other models have also been proposed (116,119). There is considerable evidence that ER materials behave as linear viscoelastic fluids while under the influence of electric field (120) thus it appears that these materials maybe thought of as elastic Bingham fluids. 

Recently, an electrorheological effect, i.e., an increase in the viscosity and dynamic shear moduli of lecithin/n-decane solutions in the presence of small amounts of polar additives (water or glycerol) when an external electric field is applied to the system, has been observed [65]. 

Electrorefining plants, for tin, 24 789 Electrorheological (ER) fluids, 21 718-719 cerium applications, 5 689-690 Electrorheological materials, 22 708t, 714-715, 721t... 

Electrorheology (ER), hybrid organic-inorganic materials in, 13 550 Electroslag remelt (ESR) processing,... 

A] As a result of applying a magnetic field, the poles of tiny magnetic particles in a magnetostrictive material line up, which alters the shape of the material. [B] The application of an electric field aligns particles in an electrorheological fluid. 

A type of material known as shape memory alloy (SMA) can perform this trick. SMAs are more complicated than electrorheological fluids and the other smart materials previously described in this chapter. An SMA does not only react or respond to environmental conditions, it also has a memory that enables it to return to a specific structure, or sometimes switch between two different structures. After the material has been set, it can recover from a deformation that would be permanent in other materials. When the temperature is raised by an amount that depends on the specific material, it snaps back into shape automatically. The memory is based on phase transitions, as described in the sidebar on page 120. 

Willis M. Winslow, an engineer and inventor, files a U.S. patent that includes the first description of an electrorheological fluid. 

University of Alberta. Educational Software for Micromachines and Related Technologies. Available online. URL http //www. cs.ualberta.ca/ database/MEMS/sma mems/index2.html. Accessed May 28,2009. Research groups at the University of Alberta in Canada constructed this Web resource, which discusses a variety of smart materials, including shape-memory alloys, piezoelectric materials, and electrorheological and magnetorheological fluids. 

National Aeronautics and Space Administration—Ames Education Division Smart Materials. Available online. URL http //virtualskies.arc. nasa.gov/research/youDecide/smartMaterials.html. Accessed May 28, 2009. As part of an educational activity in which students plan an aviation research project, this Web site provides links to pages discussing piezoelectric materials, electrorheological and magnetorheological fluids, shape-memory alloys, and magnetostrictive materials. 

The concept of microfabrication on powder surfaces can be used in many industrial fields, e.g., in pigments, printing inks, paints, foods, pharmaceuticals, detergents, cosmetics, dental materials, implant materials, copy toners, ceramics, cements, electrorheological materials, and metallurgy, etc. (I). 

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