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Dissipation Factor:  A measure of loss-rate of power of a mode of oscillation (mechanical, electrical, or electromechanical) in a dissipative system.  It is the reciprocal of Quality factor, which represents the quality of oscillation.  For example, electric power is dissipated in all dielectric materials, usually in the form of heat.  In a dielectric only one of either the conduction electrons or the dipole relaxation typically dominates loss.

Electrokinetic Phenomenon:  A family of several different effects that occur in heterogeneous fluids or in porous bodies filled with fluid.  The term heterogeneous here means a fluid containing particles.  Particles can be solid, liquid or gas bubbles with sizes on the scale of a micrometer or nanometer.  There is a common source of all these effects – the so-called interfacial 'double layer' of charges. Influence of an external force on the diffuse layer generates tangential motion of a fluid with respect to an adjacent charged surface.  This force might be electric, pressure gradient, concentration gradient, gravity. In addition, the moving phase might be either continuous fluid or dispersed phase.


 Schematic of Dental Ceramic EPD Nanoprocess

Suspended in an aqueous solution, particles of alumina have a negative charge on their surface.  A negative charge DC field moving through the solution produces a positive charge distortion in the “electric double layer” around the particles, thereby causing the particles to move toward the die.  Packing begins when electrophoretic and electrostatic forces still dominate and then yield to Van der Waals forces.

Electrophoresis:  The best-known electrokinetic phenomenon. It was discovered by Reuss in 1807. He observed that clay particles dispersed in water migrate under influence of an applied electric field. Generally, electrophoresis is the motion of dispersed particles in a fluid under the influence of an electric field. Electrophoresis occurs because particles dispersed in a liquid almost always carry an electric surface charge.  An electric field exerts electrostatic Coulomb force on the particles causing a “distortion of the electric double layer” and motion away from the source of the field.  The speed of this motion v is proportional to the electric field strength E if the field is not too strong.  Using this assumption makes it possible to introduce electrophoretic mobility μe as a coefficient of proportionality between particle speed and electric field strength:


Multiple theories were developed during 20th century for calculating this parameter.


Electrophoretic Deposition:  (EPD), is a term for a broad range of industrial processes which includes electrocoating, cathodic electrodeposition, electrophoretic coating, and electrophoretic painting.  A characteristic feature of this process is that colloidal particles suspended in a liquid medium migrate under the influence of an electric field (electrophoresis) and are deposited onto an electrode.  All colloidal particles that can be used to form stable suspensions and that can carry a charge can be used in electrophoretic deposition.  This includes material classes such as polymers, pigments, dyes, ceramics and metals.  The process is useful for applying materials to any electrically conductive surface.  The materials which are being deposited are the major determining factor in the actual processing conditions and equipment which may be used.  Due to the wide utilization of electrophoretic painting processes in many industries, aqueous EPD is the most common commercially used EPD process.  However, non-aqueous electrophoretic deposition applications are known.  Applications of non-aqueous EPD are currently being explored for use in the fabrication of electronic components and the production of ceramic coatings.  Non-aqueous processes have the advantage of avoiding the electrolysis of water and the gas evolution which accompanies electrolysis.

Green Body:  A green body refers to a ceramic compound, usually clay or ceramic powder, before it has been fully fired or sintered.

Nanoprocess:  A series of steps or acts for performing a function or accomplishing a result such as making something by moving, controlling and manipulating materials at the molecular level.

Slipcasting:  There are many forming techniques to make ceramics, but one example is slipcasting. This is where slip (liquid clay) is poured into a plaster of Paris mold. The water in the slip is drawn out of the slip, leaving an inside layer of solid clay. When this layer is thick enough, the excess slip can be removed from the mold. When dry, the solid clay can then also be removed. The slip used in slip casting is often liquefied with a substance that reduces the need for additional water to soften the slip; this prevents excessive shrinkage which occurs when a piece containing a lot of water dries.  The term slipcasting is sometimes applied to electrophoretic deposition of advanced ceramic materials such as alumina and zirconia.

Static Electric Field:  A static electric field (also referred to as electrostatic field) is an electric field that does not vary with time (frequency of 0 Hz). Static electric fields are created by electrical charges that are fixed in space. They are different from fields that change over time, such as electromagnetic fields generated by appliances using alternating current (AC) or by cell phones etc.