Results for “particle test materials”

NASA NTRS1989

Orbit transfer rocket engine technology program: Oxygen materials compatibility testing

Particle impact and frictional heating tests of metals in high pressure oxygen, are conducted in support of the design of an advanced rocket engine oxygen turbopump. Materials having a wide range of thermodynamic properties including heat of combustion and thermal diffusivity were compared in their resistance to ignition and sustained burning. Copper, nickel and their alloys were found superior to iron based and stainless steel alloys. Some materials became more difficult to ignite as oxygen pressure was increased from 7 to 21 MPa (1000 to 3000 psia).

Schoenman, Leonard↗

NASA NTRSDate not supplied

A Dynamic Testing Approach for Particulate Erosion–Corrosion for Gas Turbine Coatings

Particle interactions in gas turbine engines can be multicomponent, complex phenomena leading to the degradation of thermal (TBCs) and environmental barrier coatings (EBCs) meant to protect engine components. Ingestion of particles into the engine can lead to recession of coatings due to particle erosion. Similarly, these same particles can become molten, adhere to coatings and result in thermochemical corrosion of coating materials. Particle erosion testing is often carried out where the particles are injected into a gas stream, accelerated within a nozzle, and impinge on sample. Conversely, most molten particle corrosion testing is often done in static laboratory furnaces, which does not capture the dynamic nature of deposition in application. Nevertheless, these damage mechanisms are often tested separately and no single standard exists to test both erosive and corrosive particle interactions with coating materials under relevant operating conditions for gas turbine engines. Understanding the synergies of particle interactions in engines is crucial in determining operating lifetimes of potential coating materials. Such considerations emphasize the need for realistic approaches in standardizing particle interaction testing in combustion environments. The current study outlines initial efforts at NASA Glenn’s Erosion Burner Rig Facility in improving dynamic erosion/corrosion testing methods by assessing the durability of state-of-the-art (SOA) TBC material 7 wt.% yttria stabilized zirconia (7YSZ) as a function of particle deposition rate, burner temperature, and particle size. Calibration data to determine particle deposition rate will be presented, and mass and optical profilometry measurements were utilized to estimate mass/volume loss versus deposition per increment of particulate used over time. Electron microscopy analyses were then carried out to assess coating damage after testing.

TBC↗

NASA NTRSDate not supplied

A Dynamic Testing Approach for Particulate Erosion–Corrosion for Gas Turbine Coatings

Particle interactions in gas turbine engines can be multicomponent, complex phenomena leading to the degradation of thermal (TBCs) and environmental barrier coatings (EBCs) meant to protect engine components. Ingestion of particles into the engine can lead to recession of coatings due to particle erosion. Similarly, these same particles can become molten, adhere to coatings and result in thermochemical corrosion of coating materials. Particle erosion testing is often carried out where the particles are injected into a gas stream, accelerated within a nozzle, and impinge on sample. Conversely, most molten particle corrosion testing is often done in static laboratory furnaces, which does not capture the dynamic nature of deposition in application. Nevertheless, these damage mechanisms are often tested separately and no single standard exists to test both erosive and corrosive particle interactions with coating materials under relevant operating conditions for gas turbine engines. Understanding the synergies of particle interactions in engines is crucial in determining operating lifetimes of potential coating materials. Such considerations emphasize the need for realistic approaches in standardizing particle interaction testing in combustion environments. The current study outlines initial efforts at NASA Glenn’s Erosion Burner Rig Facility in improving dynamic erosion/corrosion testing methods by assessing the durability of state-of-the-art (SOA) TBC material 7 wt.% yttria stabilized zirconia (7YSZ) as a function of particle deposition rate, burner temperature, and particle size. Calibration data to determine particle deposition rate will be presented, and mass and optical profilometry measurements were utilized to estimate mass/volume loss versus deposition per increment of particulate used over time. Electron microscopy analyses were then carried out to assess coating damage after testing.

TBC↗

NASA NTRSDate not supplied

A Dynamic Testing Approach for Particulate Erosion–Corrosion for Gas Turbine Coatings

Particle interactions in gas turbine engines can be multicomponent, complex phenomena leading to the degradation of thermal (TBCs) and environmental barrier coatings (EBCs) meant to protect engine components. Ingestion of particles into the engine can lead to recession of coatings due to particle erosion. Similarly, these same particles can become molten, adhere to coatings and result in thermochemical corrosion of coating materials. Particle erosion testing is often carried out where the particles are injected into a gas stream, accelerated within a nozzle, and impinge on sample. Conversely, most molten particle corrosion testing is often done in static laboratory furnaces, which does not capture the dynamic nature of deposition in application. Nevertheless, these damage mechanisms are often tested separately and no single standard exists to test both erosive and corrosive particle interactions with coating materials under relevant operating conditions for gas turbine engines. Understanding the synergies of particle interactions in engines is crucial in determining operating lifetimes of potential coating materials. Such considerations emphasize the need for realistic approaches in standardizing particle interaction testing in combustion environments. The current study outlines initial efforts at NASA Glenn’s Erosion Burner Rig Facility in improving dynamic erosion/corrosion testing methods by assessing the durability of state-of-the-art (SOA) TBC material 7 wt.% yttria stabilized zirconia (7YSZ) as a function of particle deposition rate, burner temperature, and particle size. Calibration data to determine particle deposition rate will be presented, and mass and optical profilometry measurements were utilized to estimate mass/volume loss versus deposition per increment of particulate used over time. Electron microscopy analyses were then carried out to assess coating damage after testing.

burner rig↗

NASA NTRSDate not supplied

Computational Fluid Dynamics Models of the NASA White Sands Test Facility Particle Impact Test Nozzles

The particle impact ignition mechanism is considered to be the most effective means for igniting metals in gaseous oxygen environments and is a concern for every oxygen system. For this reason, the National Aeronautics and Space Administration (NASA) commits a large amount of resources attempting to understand and defend against this phenomenon. The most practical means of accomplishing this is through extensive of testing. To this end, over the years NASA has developed and built a facility and various apparatuses to test material or component vulnerability to a particle impact ignition. In testing materials, NASA uses sub-sonic and supersonic nozzles to replicate the conditions that a material is expected to experience in service. However, challenges include obtaining an understanding of the gas dynamics and of the particle behavior through and up to the point of impact at the material under test. One means of addressing these challenges is the use of computational fluid dynamics (CFD). If a CFD model can be built and validated, the model can then be used to confidently interrogate changes to inlet conditions and particle geometries, as well as changes to nozzle geometries to better simulate a material’s in-situ conditions and greatly reduce or eliminate trial-and-error approaches in testing. This paper will show NASA’s approach to and results of using CFD to better understand their particle impact nozzles.

Computational Fluid Dynamics↗

NASA NTRS2004

Subscale Testing of Nozzle Ablative Materials in a Supersonic Particle Impingement Environment

Recent efforts to evaluate materials to replace the current NARC rayon used in the nozzle ablative of the NASA's Reusable Solid Rocket Motor (SRM), several tests were developed to look at the performance of supersonic particle impact region of the aft exit cone. It was seen in early testing that some potential candidates did not perform as well as the current NARC based material and so the 24 inch Solid Rocket Motor (SRTM) exit cone design was extended and contoured to induce particle impingement in the aft end. The SRTM testing provided a larger testbed to evaluate the results seen in the Solid Fuel Supersonic Blast Tube. Testing was performed in each test bed on two variants of the final two candidate materials. The materials were a standard prewoven Lyocell, a postwoven Lyocell, an Enka rayon, and Enka rayon processed at a higher carbonization temperature. This paper presents the results of the four materials in the SSBT and the SRTM tests as compared against the NARC baseline. Erosion, char, and plylift results are discussed in detail.

Howse, S.↗

NASA NTRS2001

Development of a Low-Cost, Subscale Test System to Evaluate Particle Impingement Erosion in Nozzle Ablative Materials

This viewgraph presentation gives an overview on the development of a low-cost, subscale test system to evaluate particle impingement erosion in nozzle ablative materials. Details are given on the need for a new test bed, solid fuel torch components, solid fuel torch test, additional uses for the solid fuel torch, the development of a supersonic blast tube (SSBT), and particle impingement material discrimination.

Lansing, Matthew D.↗

NASA NTRSDate not supplied

Ignition of Metals in Heated Supersonic Particle Impact with Inert Particulate

The conventional understanding of particle impact ignition characteristic elements relies on the following principles: 1) flammable particulate (except in the case of titanium and aluminum target materials); 2) gas velocity greater than 100 ft/s; 3) Impact point ranging from 45° to perpendicular to the path of the particle [1]; 4) flammable target material. To test assumptions about particulate flammability being necessary for particle impact ignition of less reactive target materials, such as Inconel 718, testing was performed with inert particulate. Supersonic particle impact testing was conducted with heated gas and 1500-µm sapphire particulate on various target materials: 304 stainless steel, wrought and selective laser melted Inconel 718, and Monel 400. Posttest characterization of impact craters was performed on each type of metallic target sample, including surface characterization performed by light optical microscopy and scanning electron microscopy with energy dispersive spectroscopy. Full consumption of the stainless steel and wrought Inconel 718 targets were noted to occur with sequential impacts. The results of testing will be discussed in detail, as well as recommendations for updating the understanding of the particle impact ignition mechanism.

Particle Impact↗

NASA NTRS1972

The determination and optimization of (rutile) pigment particle size distributions

A light scattering particle size test which can be used with materials having a broad particle size distribution is described. This test is useful for pigments. The relation between the particle size distribution of a rutile pigment and its optical performance in a gray tint test at low pigment concentration is calculated and compared with experimental data.

Richards, L. W.↗

NASA NTRS2000

Materials for Low-Energy Neutron Radiation Shielding

Various candidate aircraft and spacecraft materials were analyzed and compared in a low-energy neutron environment using the Monte Carlo N-Particle (MCNP) transport code with an energy range up to 20 MeV. Some candidate materials have been tested in particle beams, and others seemed reasonable to analyze in this manner before deciding to test them. The two metal alloys analyzed are actual materials being designed into or used in aircraft and spacecraft today. This analysis shows that hydrogen-bearing materials have the best shielding characteristics over the metal alloys. It also shows that neutrons above 1 MeV are reflected out of the face of the slab better by larger quantities of carbon in the material. If a low-energy absorber is added to the material, fewer neutrons are transmitted through the material. Future analyses should focus on combinations of scatterers and absorbers to optimize these reaction channels and on the higher energy neutron component (above 50 MeV).

Singleterry, Robert C., Jr.↗

NASA NTRSDate not supplied

Analog Environments for Venus Aerosol Instrument and Mission Concept Testing

The most common hypothesis discussed for life on Venus is a habitat in the dense, persistent clouds, which are primarily sulfuric acid with a secondary water component. Although Earth lacks a complete Venus analog environment, several partial analogs exist which can inform our understanding of the requirements for cloud habitability as well as serving as potential testbeds for future Venus instruments or missions. Earth’s tropospheric clouds have larger particles, more water, and shorter lifetimes than Venus’s; however, they have a partial overlap in pressure and temperature, and are our only example of an airborne habitat.They can inform how particle residence time and microbial generation time constrain habitable atmospheric regions. On the biological side, this includes available nutrients and energy, environmental stressors such as radiation, osmotic potential and acidity, and time spent in protective but inactive forms (endospores, cysts, akinetes); on the physical side, gravity, air density and viscosity, thermal lofting, gravity waves, scavenging due to precipitation, and other airflow dynamics, as well as effective particle radius and electrical charge. They can also enable sampling strategy tests for airborne life detection, ranging from10 2 to10 8 viable cells/mL (10 -3 to 10 -9 cells/particle). Conversely, Earth's stratospheric sulfate layer lacks an active microbial presence, and is at a colder and less dense altitude but has partially analogous values in terms of H2SO4 and water concentration, particle size, and number density. These aerosols are accessible to aircraft and high-altitude balloons. Even more accessible potential analogs include sea spray, which overlaps with the smaller (haze) particle sizes and densities at Venus and contains trace organic constituents; marine fog, which at higher densities can match Venus’s larger (Mode 2) particle properties and contains a range of trace compounds including ammonia, phosphates, sulfates, and nitrates; and spray from acidic hydrothermal systems, which can cover a wide variety of sizes, densities, and chemical compositions. These analogs could improve the development of Venus cloud sampling instruments or sondes, including field tests of material compatibility, particle capture efficiency, and analysis sensitivity.

Analog↗

NASA NTRS1977

Ion beam plume and efflux characterization flight experiment study

A flight experiment and flight experiment package for a shuttle-borne flight test of an 8-cm mercury ion thruster was designed to obtain charged particle and neutral particle material transport data that cannot be obtained in conventional ground based laboratory testing facilities. By the use of both ground and space testing of ion thrusters, the flight worthiness of these ion thrusters, for other spacecraft applications, may be demonstrated. The flight experiment definition for the ion thruster initially defined a broadly ranging series of flight experiments and flight test sensors. From this larger test series and sensor list, an initial flight test configuration was selected with measurements in charged particle material transport, condensible neutral material transport, thruster internal erosion, ion beam neutralization, and ion thrust beam/space plasma electrical equilibration. These measurement areas may all be examined for a seven day shuttle sortie mission and for available test time in the 50 - 100 hour period.

Sellen, J. M., Jr.↗

NASA NTRS2003

Non-destructive evaluation method employing dielectric electrostatic ultrasonic transducers

An acoustic nonlinearity parameter (.beta.) measurement method and system for Non-Destructive Evaluation (NDE) of materials and structural members novelly employs a loosely mounted dielectric electrostatic ultrasonic transducer (DEUT) to receive and convert ultrasonic energy into an electrical signal which can be analyzed to determine the .beta. of the test material. The dielectric material is ferroelectric with a high dielectric constant .di-elect cons.. A computer-controlled measurement system coupled to the DEUT contains an excitation signal generator section and a measurement and analysis section. As a result, the DEUT measures the absolute particle displacement amplitudes in test material, leading to derivation of the nonlinearity parameter (.beta.) without the costly, low field reliability methods of the prior art.

Yost, William T.↗

NASA NTRSDate not supplied

The Use of Immersion Rigs for High Temperature Hydrogen Exposure Testing Within the Nuclear Thermal Rocket Element Environmental Simulator (NTREES)

The Nuclear Thermal Rocket Element Environmental Simulator (NTREES) was designed to perform non-nuclear testing of nuclear thermal rocket (NTR) fuel elements and materials. NTREES can simulate the thermal hydraulic environment within an NTR and has been leveraged to provide critical information on component performance and material compatibility. NTREES has the ability to expose test articles to pressurized Hydrogen gas up to 1000 psig and 225 g/s. NTREES tests are operated in a deoxygenated environment of Nitrogen or Argon pressurized up to 1000 psig. NTREES simulates fission heat through induction heating powered by a 1.2 MW AC power supply, and NTREES has recorded temperatures exceeding 3700K. To perform hot Hydrogen exposure tests on materials more rapidly and earlier in the fuel development process, NTREES must be able to test small material samples on the order of 1 square inch in volume, individual fuel assembly subcomponents, and particle materials. To meet these needs, multiple testing rigs have been developed to immerse test specimens in hot Hydrogen, with each "immersion rig" varying in its capability of sample type and performance range in order to meet the broadest range of testing needs. Herein is a discussion of a selection of these “immersion rigs.”

Nuclear Thermal Propulsion↗

NASA NTRS1968

Hydrostatic testing of porous assemblies

Pores of the material were plugged with dust particles suspended in water. The plugging material used was a standard test dust prepared as a slurry in distilled water. This technique provides a permanent high-integrity seal for porous material without affecting its physical properties, yet permitting pressure testing to verify structural adequacy.

Bigelow, W. L.↗

NASA NTRS2019

Regolith Particle Erosion of Material in Aerospace Environments

This paper studies the effect of exposing thermal control S13GP:6N/LO-I white paint, Kapton flex cable, fiber optic cable, HEPA filter, and M55J graphite composite to high-velocity regolith environment that spacecraft landing on Mars are commonly exposed to. Due to the similarity between the Mars 2020 Rover design and Mars Science Laboratory design, it is expected that the Mars 2020 rover will be exposed to a similar high-speed regolith environment that the Mars Science Laboratory was exposed to. This environment is replicated to test the survivability of susceptible materials. The testing is performed at the University of Dayton Research Institute in Dayton, Ohio. The experiments expose different materials to basaltic–like particles ranging in size from approximately 40 μm to 2 cm, at velocities ranging from 19 m/s to 250 m/s, with varied particle fluxes (measured in mg/cm2). Depending on the size of the particle used, the particles can either embed in or erode the material. Posttest analysis shows that all materials tested will survive the expected environment observed during the Mars 2020 landing event. Some materials are tested to failure in order to better characterize material response. Materials that fail in some test scenarios include the paint, fiber optic cable, and the graphite composite. After being exposed to regolith, the α/ε ratio of the paint increased by ~37% due to particles embedding in the paint. Darkening of the paint can negatively affect thermal control of the rover. With high particle mass fluxes, the paint eventually degraded enough to expose the aluminum substrate. When impacted by a 1.5 cm particle traveling at 20 m/s, the fiber optic cable did not sever, but the impact did cause the cable to deform enough to crack the glass, which resulted in a significant increase in attenuation, rendering the cable unable to transmit data. The graphite composite also failed when exposed to high particle fluxes. All of the observed failures occurred for test cases above the expected landing environment with significant margin. Tests performed beyond the requirements help characterize how well these materials will survive in even more extreme environments for future missions.

Abid, Mohamed↗

NASA NTRS2010

Copoly(imide siloxane) Abhesive Materials with Varied Siloxane Oligomer Length

In this work, low surface energy copoly(imide siloxane)s were synthesized with various siloxane segment lengths. Characterization of these materials revealed that domain formation of the low surface energy component within the matrix was more prevalent for longer siloxane segments as indicated by increased opacity, decreased mechanical properties, and variation of the Tg. Incorporation of siloxanes lowered the polymer s surface energy as indicated by water contact angle values. Topographical modification of these materials by laser ablation patterning further reduced the surface energy, even generating superhydrophobic surfaces. Combined, the contact angle data and particle adhesion testing indicated that copoly(imide siloxane) materials may provide greater mitigation to particulate adhesion than polyimide materials alone. These enhanced surface properties for abhesive applications did result in a reduction of the tensile moduli of the copolymers. It is possible that lower siloxane loading levels would result in retention of the mechanical properties of the polyimide while still affording abhesive surface properties. This hypothesis is currently being investigated. Laser ablation patterning offers further reduction in particle retention as the available surface area for particle adhesion is reduced. Pattern variation and size dependencies are currently being evaluated. For the purposes of lunar dust adhesion mitigation, it is likely that this approach, termed passive due to the lack of input from an external energy source, would not be sufficient to mitigate surface contamination or clean contaminated surfaces for some lunar applications. It is feasible to combine these materials with active mitigation strategies - methods that utilize input from external energy sources - would broaden the applicability of such materials for abhesive purposes. Collaborative efforts along these lines have been initiated with researchers at NASA Kennedy Space Center where experiments are being conducted involving a series of embedded electrodes within polymeric matrices.

Wohl, Christoper J.↗

NASA NTRS2019

Enhancement of the AC RPA

The overall goal of this research project is to improve the response and sensitivity of the AC Retarding Potential Analyzer (RPA). The AC RPA can accurately measure the flux, energy, and energy distribution of charged particles in a space environment. The enhancement of the sensor derives from changes that increase sensitivity of flux measurements through reduction of the baseline noise. The enhanced AC RPA sensor allows diagnosis of required charge particle beams necessary for tests of materials, instruments and subsystems, for future exploration missions.

Israel, Mordecai Ben↗