What Does Electrical Constriction Resistance Mean?
Electrical constriction resistance is resistance that occurs when electricity is impeded by an incomplete surface contact between two electrically conductive objects. Unintended resistance reduces the efficiency of electrical circuits and generates heat.
Corrosionpedia Explains Electrical Constriction Resistance
In virtually every instance where surfaces contact each other there will be some degree of electrical constriction resistance because at a microscopic level every surface has peaks and valleys. Surfaces will contact at their microscopic peaks, but where microscopic recesses occur on a surface it is likely that a gap will be created between it and the other surface. This gap increases the electrical constriction resistance of the contacting surfaces because the medium in the gap (typically air) is a poorer conductor of electricity than the materials themselves.
When electricity is ran through two or more contacting surfaces, the amount of constriction resistance can be reduced over time because the electricity eventually causes the materials to weld together. This welding creates a greater amount of contact among the materials, resulting in less air in between them. This reduces the constriction resistance both in terms of electrical conductivity and in terms of thermal conductivity.