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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Examination of Hybrid Metal Coatings for Mitigation of Fission Product Release and Corrosion Protection of LWR SiC/SiC

There is a need to increase the safety margins of current and future light water reactors (LWRs) due to the unfortunate events at Fukushima Daiichi Nuclear Plant. Safety is crucial to restore public confidence in nuclear energy, acknowledged as an economical, high-­density energy solution to climate change. The development of accident-­tolerant fuel (ATF) concepts is crucial to this endeavor. The objective of ATF is to delay the consequences of accident progression, being inset in high temperature steam and maintaining high thermomechanical strength for radionuclide retention. The use of advanced SiCf-­SiC composite as a substitute for zircaloy-­based cladding is being considered. However, at normal operations, SiC is vulnerable to the reactor coolant and may corrode at an unacceptable rate. As a ceramic-­matrix composite material, it is likely to undergo microcracking operation, which may compromise the ability to contain gaseous fission products. A proposed solution to both issues is the application of mitigation coatings for use in normal operations. At Oak Ridge National Laboratory (ORNL), three coating technologies have been investigated with industry collaborators and vendors. These are electrochemical deposition, cathodic arc physical vapor deposition (PVD hereafter) and vacuum plasma spray (VPS). The objective of this document is to summarize these processing technologies, the resultant as-­processed microstructures and properties of the coatings. In all processes, substrate constraint resulted in substantial tensile stresses within the coating layer. Each technology must mitigate this tensile stress. Electrochemical coatings use chromium as the coolant facing material, and are deposited on a nickel or carbon “bond coat”. This is economical but suffers microcracking in the chromium layer. PVD-­based coatings use chromium and titanium in both metallic form and nitrides, and can be deposited defense-­in-­depth as multilayers. This vapor method eliminated tensile stress during processing and coatings were up to ~30 μm thick without microcracking. VPS produced coatings based on Zircaloy-2, which has a proven reactor-­compatibility. The tensile stresses appearred to be partially mitigated by annealing. Analysis showed that VPS coatings required further optimizations to prevent adverse reactions with the substrate and need a minimum thickness of ~50 μm. In addition, development of coatings are constrained by neutronic depletion analysis, which clearly indicated enrichment as an issue if the coating is too thick. Based on the present work, the cathodic arc PVD technology was considered ready for the extensive testing and evaluation on cladding materials due to their ability to mitigate the excessive tensile stresses and the reasonable coating quality achieved. The VPS Zircaloy-­2 coating technology required additional development toward mitigation of issues related to the substrate reaction and porosity. In the future, PVD and VPS will have be scaled upon successful development and demonstration. Electrochemical coatings, which are proven scalability, currently require development to mitigate issues related to the tensile stress after deposition.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
NASA NTRS1983

Corrosion-Protection Coatings for Aluminum

Study investigates 21 combinatios of surface treatments, primers and topcoats. Study considers several types of coatings, including primers, enamels, chlorinated rubbers, alkyds, epoxies, vinyls, polyurethanes, waterbased paints, and antifouling paints. 20-page report summarizes the study.

Higgins, R. H.↗
DOE OSTI2014

HVOF Thermal Spray TiC/TiB2 Coatings of AUSC Boiler/Turbine Components for Enhanced Corrosion Protection

Supercritical Rankine cycles facilitate the attainment of higher efficiencies and lowered emissions. The high temperatures and enhanced reactivity of supercritical water still pose significant risk of degradation and fatigue from oxidizing, corroding and eroding environment. In addition, ash particulates and unburnt carbon and pyritic sulfur can cause erosion of the surface and thus loss of material. Unburnt carbon and pyritic sulfur may also cause localized reduction sites TiC and TiB2 are suitable coating alternatives on account of the material features such as the high hardness, the high melting point, the high strength, low density and chemical stability required for long-term service. The paper presents the research endeavors to synthesize TiC and TiB2 coatings on existing boiler materials for applications at high temperatures (500 -750 oC) and high pressures (~350 bars) using the HVOF process and to demonstrate the feasibility of these coating to be used in AUSC boilers and turbines.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2018

Solar energy protects steels against corrosion: Enhanced protection capability achieved by NiFeOx decorated BiVO4 photoanode

Highlights: • Steel corrosion is inhibited by coupling to irradiated photoanode. • NiFeO{sub x} promotes charge transfer from BiVO{sub 4} to connected steel. • BiVO{sub 4} composite photoanode decreases the self-corrosion potential of 316 steel by 256 mV. - Abstract: Coupling n-type semiconductor photoelectrode with steels provides protection from corrosion for the latter by pumping electrons produced by water oxidation reaction in a sustainable way. Although the concept of the photocathodic protection of steels has been proposed for about two decades, this technique is still far away from practical applications due to the limited protection capability. In this work, we reported that the BiVO{sub 4} photoanode significantly decreases the self-corrosion potential of 316 steel by 166 mV, and the decoration of NiFeO{sub x} films onto BiVO{sub 4} further shifts the self-corrosion potential by ∼90 mV negatively, which exhibits an excellent protection capability. The protection capability of the photoelectrode to steel is limited by the relative position of the Fermi level of the semiconducting material, and confined by the thermodynamics of the surface reactions on the semiconductor-electrolyte interface.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS2009

Refractory Materials for Flame Deflector Protection System Corrosion Control: Flame Deflector Protection System Life Cycle Cost Analysis Report

A 20-year life cycle cost analysis was performed to compare the operational life cycle cost, processing/turnaround timelines, and operations manpower inspection/repair/refurbishment requirements for corrosion protection of the Kennedy Space Center launch pad flame deflector associated with the existing cast-in-place materials and a newer advanced refractory ceramic material. The analysis compared the estimated costs of(1) continuing to use of the current refractory material without any changes; (2) completely reconstructing the flame trench using the current refractory material; and (3) completely reconstructing the flame trench with a new high-performance refractory material. Cost estimates were based on an analysis of the amount of damage that occurs after each launch and an estimate of the average repair cost. Alternative 3 was found to save $32M compared to alternative 1 and $17M compared to alternative 2 over a 20-year life cycle.

Calle, Luz Marina↗
DOE OSTI2016

Chemical conversion coating for protecting magnesium alloys from corrosion

A chromate-free, self-healing conversion coating solution for magnesium alloy substrates, composed of 10-20 wt. % Mg(NO.sub.3).sub.2.6H.sub.2O, 1-5 wt. % Al(NO.sub.3).sub.3.9H.sub.2O, and less than 1 wt. % of [V.sub.10O.sub.28].sup.6- or VO.sub.3.sup.- dissolved in water. The corrosion resistance offered by the resulting coating is in several hundreds of hours in salt-spray testing. This prolonged corrosion protection is attributed to the creation of a unique structure and morphology of the conversion coating that serves as a barrier coating with self-healing properties. Hydroxoaluminates form the backbone of the barrier protection offered while the magnesium hydroxide domains facilitate the "slow release" of vanadium compounds as self-healing moieties to defect sites, thus providing active corrosion protection.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Structure and Anticorrosion, Friction, and Wear Characteristics of Pure Diamond-Like Carbon (DLC), Cr-DLC, and Cr-H-DLC Films on AZ91D Mg Alloy

This study evaluated the protection against corrosion and wear afforded to AZ91D Mg alloy by coatings of hydrogen-free and low-Cr-doped hydrogenated diamond-like carbon (DLC) films. The microstructure and corrosion resistance were evaluated using scanning electron microscopy, atomic force microscopy, Raman spectroscopy, polarization curves, and neutral salt spraying tests. Wear tests were performed to investigate the friction and wear behaviors of the samples against 9Cr18 in humid air, deionized water, and 3.5 wt.% NaCl solution using a reciprocating sliding test in the ball-on-disk mode. The results showed that the more compact Cr-H-DLC film improved the corrosion resistance of the Mg alloy, whereas the Cr-DLC film accelerated the corrosion in the 3.5 wt.% NaCl solution. All Mg alloy samples coated with DLC films exhibited low coefficient of friction (COF) values and smaller wear volumes compared with those of bare substrate in air, water, or NaCl solution. The Cr-DLC film presented the lowest COF and wear rate in air, but the worst corrosion protection in air and NaCl solution, whereas the converse was found for the Cr-H-DLC film. Unfortunately, all coated samples showed limited protection ability because of pore defects in the films, high galvanic potential between the substrate and the buffer layer or film, and high electrical conductivity, which caused severe tribocorrosion of the Mg alloy during the wear tests in NaCl solution. The corrosion protection ability of DLC films is key to the wear resistance protection of Mg alloys in water or NaCl solution.

36 MATERIALS SCIENCE↗
NASA NTRS2012

Environmentally Friendly Corrosion Preventative Compounds

The objective of the Ground Systems Development and Operations Program Environmentally Friendly Corrosion Protective Coatings and Corrosion Preventive Compounds (CPCs) project is to identify, test, and develop qualification criteria for the use of environmentally friendly corrosion protective coatings and CPCs for flight hardware and ground support equipment. This document is the Final Report for Phase I evaluations, which included physical property, corrosion resistance, and NASA spaceport environment compatibility testing and analysis of fifteen CPC types. The CPCs consisted of ten different oily film CPCs and five different wax or grease CPC types. Physical property testing encompassed measuring various properties of the bulk CPCs, while corrosion resistance testing directly measured the ability of each CPC material to protect various metals against corrosion. The NASA spaceport environment compatibility testing included common tests required by NASA-STD-6001, "Flammability, Odor, Offgassing, and Compatibility Requirements and Test Procedures for Materials in Environments that Support Combustion". At the end of Phase I, CPC materials were down-selected for inclusion in the next test phases. This final report includes all data and analysis of results obtained by following the experimental test plan that was developed as part of the project. Highlights of the results are summarized by test criteria type.

Preventative Compounds↗
NASA NTRS2015

Characterization of Encapsulated Corrosion Inhibitors Containing Microparticles for Environmentally Friendly Smart Coatings

This poster presents the results obtained from experiments designed to evaluate the release properties, as well as the corrosion inhibition effectiveness, of several encapsulated corrosion inhibitors. Microencapsulation has been used in the development of environmentally friendly multifunctional smart coatings. This technique enables the incorporation of autonomous corrosion detection, inhibition and self-healing functionalities into many commercially available coating systems. Select environmentally friendly corrosion inhibitors were encapsulated in organic and inorganic pH-sensitive microparticles and their release in basic solutions was studied. The release rate results showed that the encapsulation can be tailored from fast, for immediate corrosion protection, to slow, which will provide continued long-term corrosion protection. The incorporation of several corrosion inhibitor release profiles into a coating provides effective corrosion protection properties. To investigate the corrosion inhibition efficiency of the encapsulated inhibitors, electrochemical techniques were used to obtain corrosion potential, polarization curve and polarization resistance data. These measurements were performed using the free as well as the encapsulated inhibitors singly or in combinations. Results from these electrochemical tests will be compared to those obtained from weight loss and other accelerated corrosion experiments.

Coatings↗
DOE OSTI2023

Mitigating Corrosion in Mg Sheet in Conjunction with a Sheet-Joining Method that Satisfies Structural Requirements within Sub-assemblies

This work was undertaken as a LightMAT project funded by the DOE-Vehicles Technology Office. The goal of this work was to develop corrosion protection strategies that simultaneously mitigate corrosion and achieve Class-A surface finish for Mg components in automotive applications. While automotive metals such as steel and aluminum are protected against corrosion through a variety of coating schemes/packages, the efficacy of these existing coating schemes for Mg and Mg- joints is not clear and needs to be determined. Therefore, five commercially available coating schemes and two joining techniques (riveting and Arplas resistance spot welding) were evaluated. The corresponding individual Mg sheet coupons or Mg/Mg joint test coupons were provided by Magna that were then corrosion tested at PNNL using ASTM B117 procedure. The microstructures and mechanical properties of the coupons were analyzed to determine the effectiveness of the joining and corrosion mitigation strategies. Of the coating schemes evaluated, Henkel Bonderite MgC 2.0 pre-treatment + E-coat showed the best corrosion protection and surface finish for individual Mg coupons and Arplas resistance spot welded coupons. However, the strength of Mg/Mg welded joint was reduced after corrosion testing due to some corrosion at the weld nugget. Mg/Mg rivet joints in conjunction with Chemetall oxisilan pre-treatment + polyurethane coating showed good corrosion resistance and some discoloration on the surface finish. Coating schemes comprising pre-treatment with Alodine 5200 + E-coat or Bonderite 1455 + polyurethane coating, in conjunction with Al rivet joints, showed significant corrosion and extensive discoloration of the surface. We anticipate that the results from this work will provide useful guidance to the automotive industry in selecting the appropriate combinations of corrosion protection coatings and joining techniques to fabricate light-weight Mg-based automotive components.

36 MATERIALS SCIENCE↗