Definition - What does Tribocharging mean?
Tribocharging is a contact electrification process that enables buildup of static electricity due to touching or rubbing of surfaces in specific combinations of two dissimilar materials.
The study of tribocharging is significant because the tribocharge formed in certain cases creates sparks, which can cause ignition of fuels and chemicals during transportation, and hence countermeasures are called for.
Corrosionpedia explains Tribocharging
Although the Greek word ''tribo" means "rubbing" or friction, in the present context, only a brief contact is needed for this process. Two dissimilar materials' surfaces just have to touch and then separate for an electric charge to develop. When there is physical contact, a chemical bond is produced between the surfaces to some extent, and charges are transferred from one surface to another. This causes a charge imbalance between those dissimilar objects.
When surfaces are separated, some bonded atoms are left with extra electrons, and some with a deficit of electrons. Part of this imbalance of electrons will be reduced due to corona discharge. Some materials can exchange electric charge of varying mobility.
A charge effect is enhanced wherever the rubbing of materials also occurs. For rough surfaces or those with differing or irregular geometry, rubbing may occasionally lead to some heating of corner protrusions, resulting in pyroelectric electric charge separation, either aiding tribocharging or nullifying the charge to some extent.
Because the material surface is electrically charged, in the case of a touch contact with an uncharged or opposite charged conducting object, a spark may be caused by the discharge of the built-up charge.
A person walking across a carpet can cause tribocharge to build up to cause a potential difference of substantial voltage (hundreds of volts) to initiate a spark that can be up to ten millimeters long. Relative humidity is also a factor in determining the rate of such tribocharging.
Even during removal of a nylon shirt, a spark can felt due to tribocharging. The friction between a car passenger's clothes and the plastics such as the vehicle's seat can produce triboelectric charge. A vehicle's body can also build up a tribocharge, which is then insulated by the carbon in the rubber tires. If the car body remains charged in a parked position, sparks may arc from the door frame to occupants, as the occupant touches the car and makes contact with the ground.
The charge polarity and strength of the charges formed vastly differ on account of the materials, quality of surface, temperature as well as other properties.