Published By National Aeronautics and Space Administration
Issued over 9 years ago
Summary
Description
<p>Corrosion is an extensive problem that impacts National Aeronautics and Space Administration (NASA) and&nbsp;Department of Defense (DoD).&nbsp; The deleterious effects of corrosion result in steep costs, asset down-time affecting mission readiness, and safety risks to personnel.&nbsp; Consequently, it is vital to reduce corrosion costs and risks in a sustainable manner.</p><p>NASA and DoD&nbsp;have numerous structures and equipment that are fabricated from stainless steel.&nbsp; The standard practice for protection of stainless steel is a process called passivation which removes free iron contamination from the surface and forms a&nbsp;metal oxide layer to prevent corrosion.&nbsp; Typical passivation procedures call for the use of nitric acid which exhibits excellent corrosion performance; however, there are a number of environmental, worker safety, and operational issues associated with its use.</p><p>The longtime military specification (QQ-P-35C) for the passivation of stainless steel was cancelled in favor of newer specifications which allow for the use of citric acid in place of nitric acid.&nbsp; Citric acid offers a variety of benefits that include increased safety for personnel, reduced environmental impact, and reduced operational cost.&nbsp; There have been few studies, however, to determine whether citric acid is an acceptable alternative for NASA and DoD applications; therefore, NASA and DoD&nbsp;agreed to collaborate on an effort to validate citric acid as an acceptable passivating agent for stainless steel.&nbsp;</p>