INTERN MPAPS G-19 PART II PDF

This specification covers the basic requirements for electrodeposited hard chromium as used to meet service conditions involving wear, corrosion, friction, or a combination of these.

Restricted Chemical Substances

All product supplied to the requirements of this specification must comply with the requirements of MPAPS B-50.

APPLICATION

Engineering coatings of chrome plate are generally used to increase the surface hardness of a part or to improve its wear resistance

Chromium plate is hard and dense with good corrosion resistance to most materials. It has a lower friction coefficient than any other metal and good anti-galling properties as long as it is not used against itself. Despite its hardness, it should not be used as a general substitute for hardening but only when properly engineered for this purpose. It may be applied to aluminum, copper, steel and cast iron substrates.

Hard chromium, as differentiated from decorative chromium, is applied for functional reasons regardless of thickness. If a 0.00005 inch (1.3 μm) deposit is applied to a surface, its apparent hardness will reflect that of the basis metal. If, however, a 0.0015-.0020 inch (38-51 μm) deposit is applied over an unhardened part, it will be hard. In short, a deposit of over 0.001 inch (25 μm) is essential before chromium will assume its true hardness characteristics when applied to unhardened basis metals, whereas over a hardened base, this thickness is not necessary because of the substantial backing provided.