NASA seeks to transfer the NASA-developed metal etching composition. This system, developed at NASA's Marshall Space Flight Center (MSFC), is superior to currently used etching compositions which are volatile and unstable. In addition to formulation advantages, this new composition has superior performance characteristics. Fluorescent penetrant inspection is utilized for the non-destructive detection of surface flaws and defects in metals. Prior to employing this process, it is necessary to chemically etch the metallic surface to remove any metal which, due to machining or grinding, may mask possible flaws. The etchant used must remove the surface metal, without harming the metal to be analyzed.

Potential Commercial Uses

The metal etching composition can be used to clean machined metal and metal alloy parts prior to inspection with fluorescent penetrant testing. Potential commercial users include aerospace, automobile and industrial parts manufacturers.

Benefits

The metal etching composition developed by MSFC is a shelf stable formulation that offers improved part cleaning characteristics compared to existing compositions.

The Technology

A commonly used etchant includes a mixture of 50 percent hydrochloric acid and 50 percent hydrogen peroxide (HCl/H₂O₂). However, this etchant has serious drawbacks. HCl/H₂O₂ often produces pitting of the metal surface, increasing the probability that an etch-induced flaw results in rejection of the part to be inspected. In addition, HCl/H₂O₂ is volatile and unstable. Because of this instability the mixture must be formed immediately prior to use. Any error in mixture concentration will greatly affect the etching process. The new composition provides an adequate surface for fluorescent penetrant inspection without over etching the surface. The result is improved accuracy of analysis and a decreased number of rejected parts. The composition exhibits a high degree of stability after formulation. Therefore, the composition can be precisely formulated, stored indefinitely and safely shipped.

Options for Commercialization

This technology is part of the NASA Technology Transfer Program. The program seeks to stimulate development of commercial applications from NASA-developed technology. The metal etching composition has been developed, tested, and implemented at MSFC. This technology is available for commercial applications.

Patent Number

5,034,093

Contact for Licensing Information

Technology Transfer Office
Patent Licensing Information
Mail Code CO30
Marshall Space Flight Center, AL 35812

Key Words

Metal Etching
Fluorescent Penetrant Inspection
Metal Inspection

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