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At least 739 records · Page 41

Thin Film Sensors for Minimally-Intrusive Measurements in Harsh High Temperature Environment

Advanced thin film sensors are being developed to provide accurate surface temperature, heat flux and strain measurements for components used in hostile propulsion environments. These sensors are sputter deposited and microfabricated directly onto the test articles with no additional bonding agent. The thickness of the sensors is only a few micrometers which creates minimal disturbance of the gas flow over the test surface. Thus thin film sensors have the advantage over conventional wire- based sensors by providing minimally intrusive measurement and having a faster response. These thin film sensors are being developed for characterization of advanced materials and structures in hostile, high-temperature environments, and for validation of design codes. This paper presents the advances of three high temperature thin film sensor technologies developed at NASA Lewis Research Center: thermocouples, heat-flux gages and strain gages. The fabrication techniques of these thin film sensors which include physical vapor deposition, photolithography patterning and lead Wire attachment are described. Sensors demonstrations on a variety of engine materials, including superalloys, ceramics and advanced ceramic matrix composites, in several hostile, high-temperature test environments are presented. The advantages and limitations of thin film sensor technology are also discussed.

Lei, Jih-Fen↗

Optical Fiber Sensors Capable of Monitoring Hydrogen in the Subsurface Hydrogen Storage Environment

Subsurface hydrogen storage is a cost-effective and environmentally friendly storage option in a large quantity. Hydrogen would be stored in subsurface storage reservoirs at high temperature/pressure under very humid condition. Monitoring hydrogen concentration in those harsh storage environments is crucial to ensure the integrity and safety of the hydrogen storage infrastructure. Thus, this project focuses on the development of optical fiber hydrogen sensors capable of monitoring hydrogen in the harsh environments that are representative of underground storage conditions. The optical fiber hydrogen sensor developed at NETL consists of a palladium-based sensing film with a filter layer which minimizes the environmental impacts on hydrogen sensing. The developed sensor has demonstrated significant improvement on hydrogen sensing at 80℃ under high humidity condition (99% RH) without the baseline drift. The hydrogen sensor also showed negligible cross-sensitivity to CO2 and CH4 which would be present as a cushion gas inside the underground hydrogen storage reservoir. Moreover, the sensor has demonstrated the stable monitoring of hydrogen concentration at high pressure (1000 psi) and 80 ℃ in the presence of biological samples. The optical fiber hydrogen sensor developed would enable reliable monitoring of hydrogen concentration in subsurface hydrogen storage facilities.

Kim, Daejin↗

Out-of-Pile Test of LVDT-Based Creep Test Rig at PWR Prototypical Conditions

New and improved materials are being considered to support the existing nuclear reactors and future next-generation reactors. The materials can significantly degrade and limit their properties in harsh reactor environments. To accurately understand the material’s degradation, real-time data is required under prototypic-irradiation conditions. Additionally, understanding the creep behavior of materials under harsh environments is essential for an evaluation of safety concerns. To provide these capabilities, the Idaho National Laboratory’s (INL’s) High Temperature Test Laboratory (HTTL) has developed several instrumented test rigs to obtain real-time data from specimens in well-controlled pressurized water reactor (PWR) coolant conditions in the Materials and Test Reactors (MTRs). This technical report focuses on INL’s efforts to evaluate and enhance the former prototype creep test rig that relied on linear variable differential transformers in laboratory settings. Specifically, the test rig is capable of detecting changes in the length of tensile specimen, which is useful for measuring thermal expansion and creep loading.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Magnetic Field Sensing with 4H SiC Diodes: N vs P Implantation

We explore the magnetic sensing capabilities of two 4H-SiC n+p diodes fabricated by NASA Glenn which only differ in the implanted ion species, nitrogen and phosphorus, and the implant activation annealing time. We use low- and high-field electrically detected magnetic resonance (EDMR) to investigate the defect structure used to sense magnetic fields as well as to evaluate the sensitivity. In addition, we expose these devices to high energy electron radiation to evaluate the defect sensing capability in a harsh radiation environment. The results from this work will allow us to tailor our processing methods to design a more optimal 4H-SiC pn diode for magnetic field sensing in harsh environments.

Cochrane, Corey J.↗

NASA's Space Environments and Effects (SEE) Program: Contamination Engineering Technology Development

ABSTRACT The return of the Long Duration Exposure Facility (LDEF) in 1990 brought a wealth of space exposure data on materials, paints, solar cells, etc. and data on the many space environments. The effects of the harsh space environments can provide damaging or even disabling effects on spacecraft, its materials, and its instruments. In partnership with industry, academia, and other government agencies, National Aeronautics & Space Administration's (NASA's) Space Environments & Effects (SEE) Program defines the space environments and provides technology development to accommodate or mitigate these harmful environments on the spacecraft. This program provides a very comprehensive and focused approach to understanding the space environment, to define the best techniques for both flight and ground-based experimentation, to update the models which predict both the environments and the environmental effects on spacecraft, and finally to ensure that this information is properly maintained and inserted into spacecraft design programs. This paper will describe the current SEE Program and will present SEE contamination engineering technology development and risk mitigation for future spacecraft design.

Pearson, Steven D.↗

NASA's Space Environments and Effects (SEE) Program

The return of the Long Duration Exposure Facility (LDEF) in 1990 brought a wealth of space exposure data on materials, paints, solar cells, adhesives and other data on the many space environments. The effects of the harsh space environments can provide damaging or even disabling effects on a spacecraft, its sub-systems, materials and instruments. In partnership with industry, academia, and other US and international government agencies, the National Aeronautics & Space Administration's (NASA's) Space Environments & Effects (SEE) Program defines the space environments and provides technology development to accommodate or mitigate these harmful environments on the spacecraft. This program (agency-wide in scope but managed at the Marshall Space Flight Center) provides a very comprehensive and focused approach to understanding the space environment. It does this by defining the best techniques for both flight- and groundbased experimentation, updating models which predict both the environments and the environmental effects on spacecraft and ensuring that this information is properly maintained and inserted into spacecraft design programs. This paper will describe the current SEE Program and discuss several current technology development activities associated with the spacecraft charging phenomenon.

Minor, Jody↗

Overview of NASA's Space Environments and Effects (SEE) Program

The return of the Long Duration Exposure Facility (LDEF) in 1990 brought a wealth of space exposure data on materials, paints, solar cells, etc., and data on the many space environments. The effects of the harsh space environments can provide damaging or even disabling effects on a spacecraft, its materials, and its instruments. In partnership with industry, academia, and other government agencies, NASA's Space Environments and Effects (SEE) Program defines the space environments and provides technology development to accommodate or mitigate these harmful environments on the spacecraft. This program provides a very comprehensive and focused approach to understanding the space environment, defines the best techniques for both flight and ground-based experimentation, updates the models which predict both the environments and the environmental effects on spacecraft, and finally, ensures that this information is properly maintained and inserted into spacecraft design programs. This paper will describe the current SEE Program and will present potential technology development activities for the future.

Hardage, Donna M.↗

Static and Fatigue Characterization of Large Composite T-Bolt Connections in Marine Hygrothermal Environments

Fiber-reinforced polymer composites have been highlighted as ideal candidates for structural applications in marine renewable energy devices, such as tidal turbines and wave energy converters. It is well understood that harsh marine environments can cause strength degradation of composite laminates, which has been extensively researched at the coupon scale; however, no research has investigated how this translates into larger-scale composite structures. This paper presents a subcomponent-scale study which investigates the effects of hygrothermal aging and subsequent static and fatigue characterization of thick composite T-bolt connections as part of a large, multilaboratory materials research effort. Of the glass-reinforced epoxy and vinylester-epoxy matrix composites tested, both showed measurable static strength degradation (4–36%) after being hygrothermally aged, even though the composite specimens were only partially saturated with water. Under tension–tension fatigue loading, the epoxy specimens performed very well in their dry states but exhibited significant degradation after hygrothermal aging. In comparison, the vinylester-epoxy specimens had much shorter fatigue lives in their dry states but exhibited no degradation after hygrothermal aging. Overall, this research demonstrates that hygrothermal aging can have significant effects on the ultimate strengths and fatigue lives of even partially saturated thick composite T-bolt connections, indicating that degradation of the outer plies on thick composite laminates can have pronounced effects on the whole structure. It discusses the challenges of building an understanding of the effects of harsh marine environments in large-scale composite structures.

16 TIDAL AND WAVE POWER↗

NASA's Space Environments and Effects Program: Technology for the New Millennium

Current trends in spacecraft development include the use of advanced technologies while maintaining the "faster, better, cheaper" philosophy. Spacecraft designers are continually designing with smaller and faster electronics as well as lighter and thinner materials providing better performance, lower weight, and ultimately lower costs. Given this technology trend, spacecraft will become increasingly susceptible to the harsh space environments, causing damaging or even disabling effects on space systems. NASA's Space Environments and Effects (SEE) Program defines the space environments and provides advanced technology development to support the design, development, and operation of spacecraft systems that will accommodate or mitigate effects due to the harsh space environments. This Program provides a comprehensive and focused approach to understanding the space environment, to define the best techniques for both flight and ground-based experimentation, to update the models which predict both the environments and the environmental effects on spacecraft, and finally to ensure that this multitudinous information is properly maintained and inserted into spacecraft design programs. A description of the SEE Program, its accomplishments, and future activities is provided.

Hardage, Donna M.↗

Pressure-Driven Fiber-Optic Sensor for Online Corrosion Monitoring

For many industrial applications, corrosion is a life-limiting phenomenon and therefore requires careful consideration and rigorous experimental testing before structural materials can be reliably deployed, particularly in harsh chemical environments. The traditional approach to measuring corrosion requires exposing many samples to the intended environment and then extracting them individually at discrete intervals for postexposure characterization. This approach does not provide a high degree of temporal resolution, nor does it provide any real-time information regarding dynamic changes in corrosion rates. Additionally, developing an online corrosion monitor capable of surviving harsh chemical environments could provide valuable information regarding the structural health of components and changing process conditions that could accelerate corrosion. To this end, a corrosion sensor was developed based on a pressure-driven Fabry-Pérot cavity (FPC). This sensor uses a pressure control system to internally pressurize the FPC formed between the sensor’s housing and a metal-embedded singlemode optical fiber. Simultaneous measurement of the change in FPC length using low-coherence interferometry and the applied pressure enables the calculation of the relative changes in the sensor’s diaphragm thickness due to corrosion on its outer surface. Measurements were made in situ while actively corroding the sensor and were validated against surveillance specimens that were corroded simultaneously. The uncertainties in the measured corrosion were analyzed using error propagation of the uncertainties in the measured pressures and displacements and were found to be <1% of the initial diaphragm thickness.

42 ENGINEERING↗

Arcjet Testing of Micro-Meteoroid Impacted Thermal Protection Materials

There are several harsh space environments that could affect thermal protection systems and in turn pose risks to the atmospheric entry vehicles. These environments include micrometeoroid impact, extreme cold temperatures, and ionizing radiation during deep space cruise, all followed by atmospheric entry heating. To mitigate these risks, different thermal protection material samples were subjected to multiple tests, including hyper velocity impact, cold soak, irradiation, and arcjet testing, at various NASA facilities that simulated these environments. The materials included a variety of honeycomb packed ablative materials as well as carbon-based non-ablative thermal protection systems. The present paper describes the results of the multiple test campaign with a focus on arcjet testing of thermal protection materials. The tests showed promising results for ablative materials. However, the carbon-based non-ablative system presented some concerns regarding the potential risks to an entry vehicle. This study provides valuable information regarding the capability of various thermal protection materials to withstand harsh space environments, which is critical to sample return and planetary entry missions.

Agrawal, Parul↗

Geopolymer Lunar Concrete under Reduced-Pressure Curing and Vacuum Exposure

Geopolymer concrete has emerged as a promising material for constructing habitats, roads, landing pads, and other necessary infrastructure on the lunar surface. Proper in-situ resource utilization (ISRU) is an important aspect of any candidate lunar construction material. Geopolymer concrete is effective at ISRU, as the lunar regolith can be used in the “as found” condition and mixed with an alkaline solution, such as sodium silicate and sodium hydroxide, which could also be mostly produced in-situ. It is envisioned that any concrete material on the lunar surface would be deposited with additive manufacturing techniques and would require a temporary environmental enclosure to mitigate the harsh lunar environment during construction and curing, such as pressure and temperature. Data are needed to set a benchmark for the conditions to be achieved within the deployable environmental enclosure during printing, as well as the resultant material properties after the enclosure is removed. This novel study investigated the influence of reduced atmospheric pressures during the initial curing period on the compressive strength of geopolymer lunar concrete created with two types of lunar regolith simulant. The simulants used in the study represent the regolith for the lunar mare (OPRL2N) and lunar highlands (OPRH2N) regions. Results show a noticeable decline in strength with a reduction in pressure and visible degradation. After the deployable environmental enclosure is removed from the printed segment of infrastructure on the lunar surface, it would then be exposed to the harsh vacuum environment. To understand the importance of curing time required within the deployable enclosure before it is removed, samples were cast and cured for different lengths of time and then exposed to a vacuum chamber capable of achieving 100 mTorr. Control samples were also cast at the same time but left in a standard laboratory environment after curing. The weight change and compressive strength as a function of time in the vacuum chamber were monitored for up to 56 days. The results showed that exposure to the vacuum limits further reaction and strength gain in comparison to control samples left in the laboratory environment. This research is in strong alignment with the 2020 NASA Technology Taxonomy materials area (12.1) and the in-situ resource utilization area (7.1), as it provides necessary data on the geopolymer lunar concrete material to support safe and sustainable options for maintaining a human presence on the Moon.

Moon to Mars Planetary Autonomous Construction Tec↗

Controlled exposure of CuO thin films through corrosion-protecting, ALD-deposited TiO 2 overlayers

Ultra-thin film coatings are used to protect semiconductor photoelectrodes from the harsh chemical environments common to photoelectrochemical energy conversion. These layers add contact transfer resistance to the interface that can result in a reduction of photoelectrochemical energy conversion efficiency of the photoelectrode. Here, we describe the concept of a partial protection layer, which allows for direct chemical access to a small fraction of the semiconductor underlayer for further functionalization by an electrocatalyst. The rest of the interface remains protected by a stable, inert protection layer. CuO is used as a model system for this scheme. Atomic layer deposition (ALD)-prepared TiO 2 layers on CuO thin films prepared from electrodeposited Cu 2 O allow for the control of interfacial morphology to intentionally expose the CuO underlayer. The ALD-TiO 2 overlayer shrinks during crystallization, while Cu 2 O in the underlayer expands during oxidation. As a result, the TiO 2 protection layer cracks to expose the oxidized underlying CuO layer, which can be controlled by preceding thermal oxidation. Furthermore, this work demonstrates a potentially promising strategy for the parallel optimization of photoelectrochemical interfaces for chemical stability and high performance.

14 SOLAR ENERGY↗

Environmental Durability Assessment and Development of Subcomponent Test Methods for Advanced Materials in Marine Energy Applications

Marine energy developers are beginning to rely more heavily on advanced composite materials for their load-bearing structures. Understanding how these materials respond and degrade in harsh marine environments is a complex problem. Much research has been performed at smaller laboratory scales to understand the fundamental physical and chemical degradation mechanisms, but little structural testing research has been performed at larger scales to understand how these physical and chemical interactions scale and how they should be accounted for in the design process. The Advanced Materials project is a multilaboratory research collaboration that addresses these issues with the intention of reducing risks and barriers to marine energy developers wanting to adopt advanced composite materials. The National Laboratory of the Rockies has been playing a leading role in developing larger-scale testing infrastructure and test methods to validate complex numerical degradation models and standardize testing procedures to do so. This paper reviews past structural testing activities, how they have grown into current research activities, and how they will continue to evolve to directly address industry needs. This paper covers key research areas - large-scale water absorption and subsequent structural validation testing, qualification of bolted and adhesive connections, and combined submerged fatigue testing at increasing scales. It provides insights into the complex requirements for testing infrastructure and test method development to effectively qualify materials and certify marine energy structures for harsh marine environments. This research program paves the way for better guidance and standardization within the industry when adopting advanced composite materials.

16 TIDAL AND WAVE POWER↗

Evaluation of the Mechanical Properties of Innovative Spacecraft Materials under a LEO Simulated Atomic Oxygen Environment

External spacecraft materials are crucial for protecting satellites from the harsh space environment. This study evaluates the radiation effects of low Earth orbit (LEO) space weather, focusing on high-energy electron and atomic oxygen (AO) exposure, on several modern spacecraft materials. The materials under investigation are “flight duplicates" of samples scheduled for launch as part of the Materials International Space Station Experiment Flight Facility (MISSE-FF) mission in 2025. To observe changes in stress distribution within weathered polymers, the experimental setup based on the photo elasticity technique was developed

Yuliya Kuznetsova↗

Evaluation of the Mechanical Properties of Innovative Spacecraft Materials Under a Low Earth Orbit-Simulated Atomic Oxygen Environment

External spacecraft materials are crucial for protecting satellites from the harsh space environment. This study evaluates the radiation effects of low Earth orbit (LEO) space weather, focusing on high-energy electron and atomic oxygen (AO) exposure, on several modern spacecraft materials. The materials under investigation are “flight duplicates" of samples scheduled for launch as part of the Materials International Space Station Experiment Flight Facility (MISSE-FF) mission in 2025. To observe changes in stress distribution within weathered polymers, the experimental setup based on the photo elasticity technique was developed.

Yuliya Kuznetsova↗

Environmental Durability Assessment and Development of Subcomponent Test Methods for Advanced Materials in Marine Energy Applications: Preprint

Marine energy developers are beginning to rely more heavily on advanced composite materials for their load bearing structures. Understanding how these materials respond and degrade in harsh marine environments is a complex problem. Much research has been performed at smaller laboratory scales to understand the fundamental physical and chemical degradation mechanisms, but little structural testing research has been performed at larger scales to understand how these physical and chemical interactions scale and how they should be accounted for in the design process. The Advanced Materials project is a multilaboratory research collaboration that has been addressing these issues with the intention of reducing risks and barriers to marine energy developers wanting to adopt advanced composite materials. The National Laboratory of the Rockies has been playing a leading role in developing larger scale testing infrastructure and test methods to validate complex numerical degradation models and standardize testing procedures to do so. This paper provides a review of past structural testing activities and how they have grown into current research activities and will continue to evolve into the future to directly address industry needs. This paper covers key research areas large-scale water absorption and subsequent structural validation testing, qualification of bolted and adhesive connections, and conducting combined submerged fatigue testing at increasing scales. This paper provides insights into the complex requirements for testing infrastructure and test method development to effectively qualify materials and certify marine energy structures for harsh marine environments. This research program paves the way for better guidance and standardization within the industry when adopting advanced composite materials.

16 TIDAL AND WAVE POWER↗