Ultradiamond glossary. Brief explanations of specialized terms.

Glossary: brief explanations of specialized terms

Absorb and Absorption

Describe presence inside a porous structure
Compare to Adsorb and Adsorption.

Adsorb and Adsorption

Describe presence on a surface
Compare to Absorb and Absorption.

Angstrom

1/10,000,000,000 of a meter
Also one-tenth of a nanometer.

Atom, diameter of

0.2 - 0.4 nanometers
All atoms are approximately the same size.

BET method

Measures amount of gas adsorbed on a surface
Powder is placed in a chamber, air is removed, and an inert gas (such as nitrogen) is introduced. The amount of gas adsorbed by the powder is measured.
BET stands for Brunauer-Emmet-Teller.

Coefficient of Friction

Measures how easily one surface slides over another
drawing of block sliding down plane, with forces marked

Consider the simple situation in the diagram,
where a block is about to slide on an inclined surface.
(If the surface is inclined slightly more,
the block will slide downwards.)

F is the force parallel to the inclined surface,
which is almost enough to make the block slide downwards.

P is the force with which the block presses against the inclined surface.

Coefficient of static friction between the block and the inclined surface
= F / P and has no dimensions (no units).

For slippery surfaces, the coefficient of friction is low.

Crosslink

A link between chains of atoms in a polymer.
Crosslinks tie polymer molecules together into a network, forming a larger molecule.

Electroless coating

Coating with metal in a reducing chemical bath
A metal-containing compound is dissolved in a liquid bath. The object to be coated is placed in the bath. An autocatalytic (continuing by itself) chemical reduction occurs.
Also called electroless plating and chemical plating.

Electrolytic coating

Coating with metal using an electric current
A metal-containing compound is dissolved in a liquid bath. The object to be coated is placed in the bath. An electric current is passed through the object and the liquid.
Also called electroplating.

Functional group

Group of atoms causing distinctive chemical actions

Grain

An aggregate (group) of individual crystals
Bonding between grains (across grain boundaries) is less perfect than bonding within a grain.

Hardness

Common industrial measures of hardness...
Brinnel hardness:
A hard ball is forced into the surface.
Hardness = load (force) divided by the area of the spherical indentation.

Rockwell hardness:
A hard ball or cone is forced into the surface.
Hardness = the depth of penetration at a given load (force).

Vickers hardness:
A hard pyramid, with a square base, is forced into the surface.
Hardness = load (force) divided by the product of the lengths of the diagonals of the square indentation

For all calculations, appropriate units must be used..

Microsecond

1/1,000,000 of a second

Modulus of elasticity

A measure of a material's stiffness
The constant relating stress (force) and strain (deformation) within the elastic range of a material. The higher the modulus of elasticity, the stiffer the material. Also called elastic modulus and Young's modulus.

Nanometer

1/1,000,000,000 of a meter
Also 10 Angstroms.
The diameter of a fine human hair is approximately 50,000 nanometers. The diameter of an atom is approximately 0.2 - 0.4 nanometers.

Polytetrafluoroethylene

See PTFE

PTFE

Polytetrafluoroethylene - an extremely slippery, chemically inert polymer which is easily abraded in its unfilled state
Commercial versions of PTFE include Teflon.

Rubber, types of

Rubber molecular structure is polar or nonpolar
In polar rubber, the molecular chains have some atttached polar groups (groups of atoms that have an electric charge). In non-polar rubber there are no attached polar groups.

Sinter

Heat and press powder to form a solid object
Powder is heated to a temperature below its melting point.
The combination of heat and pressure weld the individual particles into a strong solid.

Sorption and Sorptive

Describes absorption and/or adsorption
See also the Glossary listings for Absorb and Adsorb.

Torr

760 Torr = normal atmospheric pressure
1 Torr = force required to support 1 millimeter of mercury.

Tribology

The technology of interacting surfaces moving in relation to each other (for example, gears)
Includes friction, lubrication, wear, corrosion, and erosion.