A metal or material that readily gives up electrons to a cathodic (noble) material. An anodic material will corrode in the presence of moisture when in contact with a cathodic metal. Anodic materials are usually replaceable, and sacrifice themselves in order to preserve the cathodic material.
Tag: science
Capillary Action
(1) the action by which the surface of a liquid where it is in contact with a solid is elevated or depressed depending on the relative attraction of the molecules of the liquid for each other and for those of the solid; (2) the siphoning of liquid into a joint or void between two adjacent surfaces.
Catalyst
An ingredient that initiates a chemical reaction or increases the rate of a chemical reaction when combined with another chemical
Cathodic
A metal or material that readily attracts electrons from an anodic material in the presence of an electrolyte (see Galvanic Series).
Combustible
Capable of burning
Combustion
A chemical process of oxidation that occurs at a rate fast enough to produce heat and usually light either as glow or flames; the process of burning.
Condensate
The liquid resulting from the condensation of a gas.
Condensation
The conversion of water vapor or other gas to liquid phase as the temperature drops; the act or process of condensing.
Condense
To make denser or more compact, as when a material (e.g., water vapor) changes from its gas phase to its liquid phase.
Copolymerization
A chemical reaction that results in the bonding of two or more dissimilar monomers to produce large, long-chain molecules that are copolymers.
Cross-linking
The formation of chemical bonds between polymeric chains. Cross-linking of rubber is referred to as vulcanization or “curing.”
Cure
A process whereby a material is caused to form permanent molecular linkages by exposure to chemicals, heat, pressure and/or weathering.
Curing Agent
An additive in a coating or adhesive that results in increased chemical activity between the components with an increase or decrease in rate of cure.
Curing Compound
A liquid that is sprayed or otherwise applied to newly placed concrete which retards the loss of water during curing.
Diffusion
The movement of water vapor from regions of high concentration (high water vapor pressure) toward regions of lower concentration.
Dry
Free or relatively free from a liquid, especially water; (2) to remove water or moisture.
Emulsion
A mixture of bitumen and water, with uniform dispersion of the bitumen or water globules, usually stabilized by an emulsifying agent or system.
Exotherm
Heat generated by a chemical reaction.
Flammability
Those characteristics of a material that pertain to its relative ease of ignition and ability to sustain combustion.
Flammable
Subject to easy ignition and rapid flaming combustion.
Force
A strength or energy exerted or brought to bear; cause of motion or change.
Galvanic Action
An electrochemical action that generates electrical current between two metals of dissimilar electrode potential.
Galvanic Series
A list of metals and alloys arranged according to their relative electrolytic potentials in a given environment.
Grain
A unit of measure in the English System of units; 7,000 grains equals 1 lb.; used as a measure of the weight of moisture in air.
Heat Transfer
The transmission of thermal energy from a location of higher temperature to a location of lower temperature. This can occur by conduction, convection or radiation.
Humidity
The condition of the atmosphere with respect to water vapor. See relative humidity.
Hydrocarbon
An organic chemical compound primarily containing the elements carbon and hydrogen.
Inorganic
Being or composed of materials other than hydrocarbons and their derivatives, or matter that is not of plant or animal origin.
Joule
A unit of energy or work; equals the work done by a force of 1 newton which acts over a distance of 1 meter in the direction of the force.
K or K-Value
Thermal conductivity; the time rate of heat flow through a unit area of a homogeneous material in a direction perpendicular to isothermal planes induced by a unit temperature gradient. In English (inch-pound) units of measurement, it is the number of BTUS that pass through a 1 inch (25 mm) thickness of a 1 square foot (0.09 m2) sample of material in 1 hour with a temperature difference between the two surfaces of 1° F. It is expressed as Btu·inch/h·ft2·°F.
Material Safety Data Sheets
A written description of the chemicals in a product and other pertinent data, including such things as safe handling and emergency procedures. In accordance with OSHA regulations, it is the manufacturer’s responsibility to produce an MSDS and the employers responsibility to communicate its contents to employees.
Moisture Contour Map
A map used to graphically define the location of moisture within a roof assembly after a moisture scan has been performed
Newton (N)
SI unit of measure for force.
Noble Metal
A metal that readily receives electrons from an anodic metal (see Galvanic series).
Non-Volatile Content
The portion of a coating that does not evaporate during drying or curing under specified conditions, comprising the binder and, if present, the pigment. (The percent volatile content is obtained by subtracting the nonvolatile content from 100.).
Nonflammable
Not easily ignited and not burning rapidly if ignited.
Nonfriable
A material that, when dry, cannot be crumbled, pulverized or reduced to powder by hand pressure.
Nonoxidizing
A material which resists oxidation in exterior exposures or accelerated weathering.
Organic
Being or composed of hydrocarbons or their derivatives, or matter of plant or animal origin.
Ozone
A triatomic form of oxygen that is a bluish gas of pungent odor; is formed naturally in the upper atmosphere by a photochemical reaction with solar ultraviolet radiation.
Ozone Resistance
The ability of a material to resist the deteriorating effects of ozone exposure.
pH
a measure of the acidity or alkalinity of a solution, with neutrality represented by a value of 7, with increasing acidity represented by increasingly smaller values, and with increasing alkalinity represented by increasingly larger values.
Relative Humidity
The ratio of the pressure of water vapor present in a given volume of air to the pressure of fully saturated water vapor at the same temperature, expressed as a percentage.
Rubber
A material that is capable of recovering from large deformations quickly and forcibly.