COATED SEAL FACE C044
A hard coating is plated or welded to a softer base material such as stainless steel.
The difference in these materials presents problems with different thermal expansion rates. Most hard coating expand and contract at one third the rate of the base material.
With the introduction of the silicon and tungsten carbides, coated materials are no longer considered reliable seal faces.
When the cracking occurred in these coated materials it is said to have heat checked.
Some people attempt to coat or “plate” a pump shaft to get corrosion resistance. Unfortunately these coatings are not thick enough.
To get corrosion resistance you need a thickness of at least 1/16 inches (1.5 mm).