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At least 163 records · Page 9

ECLSS Universal Waste Management System (UWMS) Metal Materials Compatibility Study - Elgiloy: Electrochemical and Crevice Corrosion Evaluation

Electrochemical evaluations were conducted on samples of Elgiloy in support of the materials compatibility program for the Environmental Control and Life Support System (ECLSS). Results were compared alongside three previously tested metals: Titanium 6Al-4V, Inconel 625, and Hastelloy C276. Titanium exhibited the best results of all the metals, indicating superior corrosive nobility and galvanic protection properties. Elgiloy demonstrated anti-corrosion behavior which appeared to be superior to the two nickel-chromium alloys. For this current effort, the results have clearly shown that Elgiloy possesses excellent corrosion protection properties and is galvanically compatible with the other three metals in the subject test media.

Lee, R. E.↗

Microencapsulation Technology for Corrosion Mitigation by Smart Coatings

A multifunctional, smart coating for the autonomous control of corrosion is being developed based on micro-encapsulation technology. Corrosion indicators as well as corrosion inhibitors have been incorporated into microcapsules, blended into several paint systems, and tested for corrosion detection and protection effectiveness. This paper summarizes the development, optimization, and testing of microcapsules specifically designed to be incorporated into a smart coating that will deliver corrosion inhibitors to mitigate corrosion autonomously. Key words: smart coating, corrosion inhibition, microencapsulation, microcapsule, pH sensitive microcapsule, corrosion inhibitor, corrosion protection pain

Buhrow, Jerry↗

Advanced Coating Removal Techniques

An important step in the repair and protection against corrosion damage is the safe removal of the oxidation and protective coatings without further damaging the integrity of the substrate. Two such methods that are proving to be safe and effective in this task are liquid nitrogen and laser removal operations. Laser technology used for the removal of protective coatings is currently being researched and implemented in various areas of the aerospace industry. Delivering thousands of focused energy pulses, the laser ablates the coating surface by heating and dissolving the material applied to the substrate. The metal substrate will reflect the laser and redirect the energy to any remaining protective coating, thus preventing any collateral damage the substrate may suffer throughout the process. Liquid nitrogen jets are comparable to blasting with an ultra high-pressure water jet but without the residual liquid that requires collection and removal .As the liquid nitrogen reaches the surface it is transformed into gaseous nitrogen and reenters the atmosphere without any contamination to surrounding hardware. These innovative technologies simplify corrosion repair by eliminating hazardous chemicals and repetitive manual labor from the coating removal process. One very significant advantage is the reduction of particulate contamination exposure to personnel. With the removal of coatings adjacent to sensitive flight hardware, a benefit of each technique for the space program is that no contamination such as beads, water, or sanding residue is left behind when the job is finished. One primary concern is the safe removal of coatings from thin aluminum honeycomb face sheet. NASA recently conducted thermal testing on liquid nitrogen systems and found that no damage occurred on 1/6", aluminum substrates. Wright Patterson Air Force Base in conjunction with Boeing and NASA is currently testing the laser remOval technique for process qualification. Other applications of liquid nitrogen operations include cutting of both soft and hard materials. While the laser will not cut materials, it can be used to roughen surfaces and to remove other materials from the substrate including oil, grease, and mold. The space program can benefit from several of these applications with the need for precise removal of coatings and other organic compounds in areas adjacent to sensitive space flight hardware. Significant advantages are evident when comparing liquid nitrogen and laser removal operations over current techniques of media blasting and sanding.

Seibert, Jon↗

Tests Of Polyurethane And Dichromate Coats On Aluminum

Report describes experiments to determine relative effectiveness of new polyurethane and more-conventional dichromate coat in helping to retard corrosion of anodized 6061-T6 aluminum. Concludes by suggesting greater protection against corrosion achieved by combining polyurethane-sealing method with hard-anodizing method and by increasing thickness of coat.

Danford, M. D.↗

Application of Terahertz Radiation to the Detection of Corrosion under the Shuttle's Thermal Protection System

There is currently no method for detecting corrosion under Shuttle tiles except for the expensive process of tile removal and replacement; hence NASA is investigating new NDE methods for detecting hidden corrosion. Time domain terahertz radiation has been applied to corrosion detection under tiles in samples ranging from small lab samples to a Shuttle with positive results. Terahertz imaging methods have been able to detect corrosion at thicknesses of 5 mils or greater under 1" thick Shuttle tiles and 7-12 mils or greater under 2" thick Shuttle tiles.

Madaras, Eric I.↗

Study program for encapsulation materials interface for low cost silicon solar array

An atmospheric corrosion model was developed and verified by five months of corrosion rate and climatology data acquired at the Mead, Nebraska LSA test site. Atmospheric corrosion rate monitors (ACM) show that moisture condensation probability and ionic conduction at the corroding surface or interface are controlling factors in corrosion rate. Protection of the corroding surface by encapsulant was shown by the ACM recordings to be maintained, independent of climatology, over the five months outdoor exposure period. The macroscopic corrosion processes which occur at Mead are shown to be reproduced in the climatology simulator. Controlled experiments with identical moisture and temperature aging cycles show that UV radiation causes corrosion while UV shielding inhibits LSA corrosion.

Kaelble, D. H.↗

Smart Coating for Corrosion Indication and Prevention: Recent Progress

The authors are developing a smart coating system based on pH-triggered release microcapsules. These microcapsules can be incorporated into various coating systems for corrosion detection, protection and self-repair of mechanical coating damage. This paper will present the results from progress made to date in the controlled release properties of these microcapsules as well as in their corrosion indication and corrosion inhibition function.

Li, Wenyan↗

Metallized coatings for corrosion control of Naval ship structures and components

In attempting to improve corrosion control, the U.S. Navy has undertaken a program of coating corrosion-susceptible shipboard components with thermally sprayed aluminum. In this report the program is reviewed in depth, including examination of processes, process controls, the nature and properties of the coatings, nondestructive examination, and possible hazards to personnel. The performance of alternative metallic coating materials is also discussed. It is concluded that thermally sprayed aluminum can provide effective long-term protection against corrosion, thereby obviating the need for chipping of rust and repainting by ship personnel. Such coatings are providing excellent protection to below-deck components such as steam valves, but improvements are needed to realize the full potential of coatings for above-deck service. Several recommendations are made regarding processes, materials, and research and development aimed at upgrading further the performance of these coatings.

Source record↗

Treatment Prevents Corrosion in Steel and Concrete Structures

In the mid-1990s, to protect rebar from corrosion, NASA developed an electromigration technique that sends corrosion-inhibiting ions into rebar to prevent rust, corrosion, and separation from the surrounding concrete. Kennedy Space Center worked with Surtreat Holding LLC, of Pittsburgh, Pennsylvania, a company that had developed a chemical option to fight structural corrosion, combining Surtreat's TPS-II anti-corrosive solution and electromigration. Kennedy's materials scientists reviewed the applicability of the chemical treatment to the electromigration process and determined that it was an effective and environmentally friendly match. Ten years later, NASA is still using this approach to fight concrete corrosion, and it has also developed a new technology that will further advance these efforts-a liquid galvanic coating applied to the outer surface of reinforced concrete to protect the embedded rebar from corrosion. Surtreat licensed this new coating technology and put it to use at the U.S. Army Naha Port, in Okinawa, Japan. The new coating prevents corrosion of steel in concrete in several applications, including highway and bridge infrastructures, piers and docks, concrete balconies and ceilings, parking garages, cooling towers, and pipelines. A natural compliment to the new coating, Surtreat's Total Performance System provides diagnostic testing and site analysis to identify the scope of problems for each project, manufactures and prescribes site-specific solutions, controls material application, and verifies performance through follow-up testing and analysis.

Source record↗

Sealant Applicator for Fastener Heads

Dispenses sealant, either manually or automatically, in predetermined amounts. Applicator encapsulates heads of fasteners with measured shot of sealant to protect from corrosive environments.

Sharpe, M. H.↗

Development of a rotary joint fluid coupling for Space Station Freedom

The design and development is described of a rotary joint fluid coupling for Space Station Freedom. The function of this fluid coupling is to transfer a heat rejection fluid between stationary and rotating interfaces with the Space Station thermal bus system. The design of this coupling incorporates a modular type design to allow maximum flexibility, two types of seals (mechanical face seals and shaft lip seals) for redundancy, materials with excellent ammonia compatibility, and coatings that enhance seal wear resistance and increased protection against corrosion. This design was thoroughly tested and met all design requirements. Potential applications of this hardware include uses in gun turrets, coal slurries, farming equipment, and any other applications that require the low leakage transfer of fluids between stationary and rotating interfaces.

Costulis, John A.↗