NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Electrochemical Measurement of Atmospheric CorrosionCorrosion of Shuttle thruster components in atmospheres containing high concentrations of nitrogen tetroxide (NTO) and water is an important issue in ground operations of bipropellant systems in humid locations. Measurements of the corrosivities of NTO-containing atmospheres and the responses of different materials to these atmospheres have been accomplished using an electrochemical sensor. The sensor is composed of alternating aluminum/titanium strips separated by thin insulating layers. Under high humidity conditions a thin film of water covers the surface of the sensor. Added NTO vapor reacts with the water film to form a conductive medium and establishes a galvanic cell. The current from this cell can be integrated with respect to time and related to the corrosion activity. The surface layer formed from humid air/NTO reacts in the same way as an aqueous solution of nitric acid. Nitric acid is generally considered an important agent in NTO corrosion situations. The aluminum/titanium sensor is unresponsive to dry air, responds slightly to humid air (> 75% RH), and responds strongly to the combination of humid air and NTO. The sensor response is a power function (n = 2) of the NTO concentration. The sensor does not respond to NTO in dry air. The response of other materials in this type of sensor is related to position of the material in a galvanic series in aqueous nitric acid. The concept and operation of this electrochemical corrosion measurement is being applied to other corrosive atmospheric contaminants such as hydrogen chloride, hydrogen fluoride, sulfur dioxide, and acidic aerosols.
Document ID
19990110114
Acquisition Source
White Sands Test Facility
Document Type
Conference Paper
Authors
DeArmond, Anna H.
(Allied-Signal Technical Services Corp. Las Cruces, NM United States)
Davis, Dennis D.
(Allied-Signal Technical Services Corp. Las Cruces, NM United States)
Beeson, Harold D.
(NASA White Sands Test Facility NM United States)
Date Acquired
August 19, 2013
Publication Date
April 1, 1999
Publication Information
Publication: JANNAF 28th Propellant Development and Characterization Subcommittee and 17th Safety and Environmental Protection Subcommitte Joint Meeting
Volume: 1
Subject Category
Propellants And Fuels
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

Available Downloads

There are no available downloads for this record.
No Preview Available