Silver iodide as a solid lubricant for power contacts

Silver coated electrical contacts have excellent electrical and thermal properties, although some kind of lubricant is necessary to protect against wear and corrosion and also to give acceptable friction forces during operation. We have developed thin films of silver iodide for standard silver coating as a solid lubricant. The friction coefficient is reduced and wear resistance is improved as compared to unlubricated silver coatings. Silver iodide coating on contacts in an on-load-tap-changer, an electromechanical device installed in a power transformer to regulate the voltages of the transformer under load, is one example of an application resulting in low friction, considerably improved wear resistance and a low and stable contact resistance.