Robert Maller

US Patent:

40636445, Dec 20, 1977

Filed:

Oct 12, 1976

Appl. No.:

5/731700

Inventors:

Kenneth G. Hoffman - Massapequa Park NY
Robert R. Maller - Plainview NY
Robert W. Messler - Farmingdale NY

Assignee:

Grumman Aerospace Corporation - Bethpage NY

International Classification:

B07C 5342
G01N 2116

US Classification:

2091116

Abstract:

A process for the nondestructive inspection of chromium-plated or coated metal parts. The process uses an uncomplicated electrolytic technique to etch selectively the surface of the part to thereby develop indications of thermal damage which are readily detectable by a simple visual inspection without the requirement for any further processing of the part for inspection. The process is particularly suitable for the nondestructive detection of thermal damage in hard chromium plating on a high-strength steel base metal. Damage in the base metal of the part itself, particularly that resulting from abusive grinding or other machining operations on the plating, can also be detected in the chromium plating on the part because of the excellent correlation between chromium damage and base metal damage. In the process, after the part has undergone normal pre-etch preparation, it is immersed anodically in a conventional electrolytic solvent of the plating metal and is etched for a short period of time. Thermal damage to the plating and damage induced in the base metal through the chromium plate is indicated on the surface of the plating by color anomalies which delineate the areas of damage.