Ask the Expert Question-and-Answer Archive
(Hard Chrome Plating)

by Larry Zitko, ChromeTech, Inc.
February, 2002

Information on Hard Chrome Corrosion Data

Q. We are an industrial valve manufacturer, supplying valves for a variety of applications. My department is responsible for metal-seated ball valves, where the internal components (i.e. balls and seats) are hard chrome plated for erosion and wear protection. We are supplying valves to chemical and petrochemical plants where the corrosion and erosion resistance is of importance. Would you have a chart listing various chemicals, maybe at different temperatures and hard chrome resistance level ? This would help us tremendously in selecting the proper materials.

A. It's more difficult to find published data on the chemical resistance of chromium than for other metals, which might be used as materials of construction for pumps (like stainless steel, brass, etc.). From experience and reading down through the years, I am aware of several chemicals which attack the chromium electrodeposit:

• Hydrochloric (muratic) acid.
• Hydrofluoric acid.
• Solutions containing chloride salts.
• Sulfuric acid when heated.

I found one textbook that has a good chemical resistance chart for chromium, but it's so old that it may be out of print. The book is "Heavy Deposition", authored by J. D. Greenwood, Robert Draper LTD, Teddington (Great Britain), 1970.

In Table 11, Mr. Greenwood rates the chemical resistance of heavy chromium deposits as "rapidly attacked", "slowly attacked", "fair" and "good" when in contact with various organic and inorganic acids, gases and other materials.

I cannot reproduce the copyrighted material, but you may contact me directly if you would like me to search the table for any particular acids or materials of interest.