Gear coatings for rotary gear pumps

摘要

Gears for pumping non-lubricating fluids at high pressure are provided which include special coatings. One of the gears is coated with a combination of nickel and polytetrafluoroethylene; the other gear is coated with a combination of carbon and tungsten carbide. Because the coatings are different and have different hardnesses, galling is prevented. Preferably, the gears are fabricated from stainless steel and, therefore, in the event a scratch or nick in the coating is produced, corrosion is prevented. The gears are useful for gear pumps used to pump fire fighting liquids and foam at high pressures.