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Citric Acid Passivation of Stainless SteelPassivation is a process for cleaning and providing corrosion protection for stainless steel. Currently, on Kennedy Space Center (KSC), only parts passivated with nitric acid are acceptable for use. KSC disposes of approximately 125gal of concentrated nitric acid per year, and receives many parts from vendors who must also dispose of used nitric acid. Unfortunately, nitric acid presents health and environmental hazards. As a result, several recent industry studies have examined citric acid as an alternative. Implementing a citric acid-based passivation procedure would improve the health and environmental safety aspects of passivation process. However although there is a lack of published studies that conclusively prove citric acid is a technically sound passivation agent. In 2007, NASA's KSC Materials Advisory Working Group requested the evaluation of citric acid in place of nitric acid for passivation of parts at KSC. United Space Alliance Materials & Processes engineers have developed a three-phase test plan to evaluate citric acid as an alternative to nitric acid on three stainless steels commonly used at KSC: UNS S30400, S41000, and S17400. Phases 1 and 2 will produce an optimized citric acid treatment based on results from atmospheric exposure at NASA's Beach Corrosion Facility. Phase 3 will compare the optimized solution(s) with nitric acid treatments. If the results indicate that citric acid passivates as well or better than nitric acid, NASA intends to approve this method for parts used at the Kennedy Space Center.
Document ID
Acquisition Source
Kennedy Space Center
Document Type
Yasensky, David
(United Space Alliance Cape Canaveral, FL, United States)
Reali, John
(United Space Alliance Cape Canaveral, FL, United States)
Larson, Chris
(United Space Alliance Cape Canaveral, FL, United States)
Carl, Chad
(NASA Headquarters Washington, DC United States)
Date Acquired
August 25, 2013
Publication Date
November 11, 2009
Subject Category
Mechanical Engineering
Report/Patent Number
Meeting Information
Meeting: 2011 Aircraft Airworthiness and Sustainment Conference
Location: San Diego, CA
Country: United States
Start Date: April 18, 2011
End Date: April 22, 2011
Sponsors: NASA Headquarters, Federal Aviation Administration, Department of Defense
Funding Number(s)
OTHER: J0041320A4
Distribution Limits
Public Use Permitted.
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