Study of Corrosion Protection Methods for GSE Applications at Kennedy Space Center
By: J. D. Morrison
This is a status report covering the work accomplished from February, 1970 to April, 1972 on a program, conducted for the Mechanical Design Division by the Materials Testing Branch, to evaluate corrosion control and treatment methods for Ground Support Equipment (GSE) at KSC. Present methods, as defined in a corrosion control and treatment manual prepared by DD-MDD-1, are based on sound, established practices. However, the applicability of these methods for the extremely corrosive KSC environment was not known. The purpose of the program was to evaluate the procedures recommended in the manual, using actual hardware items with the relevant treatments applied. Samples of stainless steel, aluminum, carbon steel, and galvanized steel parts were obtained and treated with various corrosion-preventative materials, such as chemical conversion coatings, paint systems, vapor-phase corrosion inhibitors, fluidized-bed coatings, tapes, solvent-cutback compounds, and greases. Duplicate sets of all specimens were prepared and place at the KSC Corrosion Test Site, one set being placed in an exposed location and the other in a sheltered location. The samples were evaluated by visual inspection.
Conclusions reached after two years of exposure testing are as follows:
For aluminum alloys, a three-coat paint system and inorganic zinc paint have given complete protection. A chemical conversion coating (MIL-C-5541) was useful for short-term protection.
For stainless steels, sacrificial type coatings (such as zinc-rich and aluminum-rich paints), polyethylene tape, and a fluidized-bed epoxy coating, gave excellent protection. A solvent cutback material, MIL-C-16173, Grade 2, was satisfactory for short-term protection.
For galvanized steel parts, none of the treatments evaluated significantly extended the life of the zinc coating.
For carbon steels, a vapor-phase corrosion-inhibiting compound (MIL-L-46002) protected internal surfaces of enclosures subject to moisture intrusion. None of the treatments applied to external surfaces, directly exposed to the seacoast environment, gave adequate long-term protection, although some of the MIL-C-16173 compounds were useful for short-term exposures.
For additional information, a complete copy of this study is available as NASA Report MAB 3221-69. Send requests for copies to firstname.lastname@example.org.
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