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At least 55 records · Page 3

Compatibility of Segments of Thermoelectric Generators

A method of calculating (usually for the purpose of maximizing) the power-conversion efficiency of a segmented thermoelectric generator is based on equations derived from the fundamental equations of thermoelectricity. Because it is directly traceable to first principles, the method provides physical explanations in addition to predictions of phenomena involved in segmentation. In comparison with the finite-element method used heretofore to predict (without being able to explain) the behavior of a segmented thermoelectric generator, this method is much simpler to implement in practice: in particular, the efficiency of a segmented thermoelectric generator can be estimated by evaluating equations using only hand-held calculator with this method. In addition, the method provides for determination of cascading ratios. The concept of cascading is illustrated in the figure and the definition of the cascading ratio is defined in the figure caption. An important aspect of the method is its approach to the issue of compatibility among segments, in combination with introduction of the concept of compatibility within a segment. Prior approaches involved the use of only averaged material properties. Two materials in direct contact could be examined for compatibility with each other, but there was no general framework for analysis of compatibility. The present method establishes such a framework. The mathematical derivation of the method begins with the definition of reduced efficiency of a thermoelectric generator as the ratio between (1) its thermal-to-electric power-conversion efficiency and (2) its Carnot efficiency (the maximum efficiency theoretically attainable, given its hot- and cold-side temperatures). The derivation involves calculation of the reduced efficiency of a model thermoelectric generator for which the hot-side temperature is only infinitesimally greater than the cold-side temperature. The derivation includes consideration of the ratio (u) between the electric current and heat-conduction power and leads to the concept of compatibility factor (s) for a given thermoelectric material, defined as the value of u that maximizes the reduced efficiency of the aforementioned model thermoelectric generator.

Snyder, G. Jeffrey↗

Oxygen Compatibility of Brass-Filled PTFE Compared to Commonly Used Fluorinated Polymers for Oxygen Systems

Safe and reliable seal materials for high-pressure oxygen systems sometimes appear to be extinct species when sought out by oxygen systems designers. Materials that seal well are easy to find, but these materials are typically incompatible with oxygen, especially in cryogenic liquid form. This incompatibility can result in seals that leak, or much worse, seals that easily ignite and burn during use. Materials that are compatible with oxygen are easy to find, such as the long list of compatible metals, but these metallic materials are limiting as seal materials. A material that seals well and is oxygen compatible has been the big game in the designer's safari. Scientists at the Materials Combustion Research Facility (MCRF), part of NASA/Marshall Space Flight Center (MSFC), are constantly searching for better materials and processes to improve the safety of oxygen systems. One focus of this effort is improving the characteristics of polymers used in the presence of an oxygen enriched environment. Very few systems can be built which contain no polymeric materials; therefore, materials which have good impact resistance, low heat of combustion, high auto-ignition temperature and that maintain good mechanical properties are essential. The scientists and engineers at the Materials Combustion Research Facility, in cooperation with seal suppliers, are currently testing a new formulation of polytetrafluoroethylene (PTFE) with Brass filler. This Brass-filled PTFE is showing great promise as a seal and seat material for high pressure oxygen systems. Early research has demonstrated very encouraging results, which could rank this material as one of the best fluorinated polymers ever tested. This paper will compare the data obtained for Brass-filled PTFE with other fluorinated polymers, such as TFE-Teflon (PTFE) , Kel-F 81, Viton A, Viton A-500, Fluorel , and Algoflon . A similar metal filled fluorinated polymer, Salox-M , was tested in comparison to Brass-filled PTFE to demonstrate the importance of the metal chosen and relative percentage of filler. General conclusions on the oxygen compatibility of this formulation are drawn, with an emphasis on comparing and contrasting the materials performance to the performance of the current state-of-the-art oxygen compatible polymers.

Herald, Stephen D.↗

An Improved Approach for Analyzing the Oxygen Compatibility of Solvents and other Oxygen-Flammable Materials for Use in Oxygen Systems

Solvents used to clean oxygen system components must be assessed for oxygen compatibility, as incompatible residue or fluid inadvertently left behind within an oxygen system can pose a flammability risk. The most recent approach focused on solvent ignition susceptibility to assess the flammability risk associated with these materials. Previous evaluations included Ambient Pressure Liquid Oxygen (LOX) Mechanical Impact Testing (ASTM G86) and Autogenous Ignition Temperature (AIT) Testing (ASTM G72). The goal in this approach was to identify a solvent material that was not flammable in oxygen. As environmental policies restrict the available options of acceptable solvents, it has proven difficult to identify one that is not flammable in oxygen. A more rigorous oxygen compatibility approach is needed in an effort to select a new solvent for NASA applications. NASA White Sands Test Facility proposed an approach that acknowledges oxygen flammability, yet selects solvent materials based on their relative oxygen compatibility ranking, similar to that described in ASTM G63-99. Solvents are selected based on their ranking with respect to minimal ignition susceptibility, damage and propagation potential, as well as their relative ranking when compared with other solvent materials that are successfully used in oxygen systems. Test methods used in this approach included ASTM G86 (Ambient Pressure LOX Mechanical Impact Testing and Pressurized Gaseous Oxygen (GOX) Mechanical Impact Testing), ASTM G72 (AIT Testing), and ASTM D240 (Heat of Combustion (HOC) Testing). Only four solvents were tested through the full battery of tests for evaluation of oxygen compatibility: AK-225G as a baseline comparison, Solstice PF, L-14780, and Vertrel MCA. Baseline solvent AK-225G exhibited the lowest HOC and highest AIT of solvents tested. Nonetheless, Solstice PF, L-14780, and Vertrel MCA HOCs all fell well within the range of properties that are associated with proven oxygen system materials. Tested AITs for these solvents fell only slightly lower than the AIT for the proven AK-225G solvent. Based on these comparisons in which solvents exhibited properties within those ranges seen with proven oxygen system materials, it is believed that Solstice PF, L-14780, and Vertrel MCA would perform well with respect to oxygen compatibility.

Harper, Susan A.↗

HFE 7100 Compatibility with Orbiter Materials

Chlorofluorocarbon (CFC) 113 is currently specified as the precision cleaning and verification fluid for orbiter materials. The production ban of CFC 113, an ozone-depleting chlorofluorocarbon, has resulted in a search for a replacement cleaning fluid. Recently, the 3M Company announced the manufacture of a new class of cleaning fluids, hydrofluoroethers. The first in this class of cleaning fluids is HFE 7100, perfluorobutyl methyl ether. This cleaning fluid has been submitted for consideration as a replacement for CFC 113. One of the requirements of the certification process for a replacement cleaning fluid is compatibility testing. The Johnson Space Center (JSC) Materials and Manufacturing Division has requested that NASA JSC White Sands Test Facility perform the compatibility testing with HFE 7100 on selected orbiter materials. Most of the materials selected for testing were previously evaluated for compatibility with CFC 113. Some of the materials are new additions to the orbiter or were not available when the compatibility testing was performed with CFC 113. These materials were evaluated with both cleaning fluids and the results were used to compare the response to the cleaning fluid and to satisfy the certification process requirements. It was found that HFE 7100 is generally compatible with the materials tested.

Chlorofluorocarbon↗

Click-chemistry compatible structures, click-chemistry functionalized structures, and materials and methods for making the same

According to various embodiments, systems, methods, and computer program products for click-chemistry compatible structures, additive manufacturing resins for forming the same, and method of formation of such structures and resins, as well as techniques for functionalizing click-chemistry compatible structures are disclosed. The inventive structures generally include a plurality of photo polymerized molecules structurally arranged according to a three-dimensional pattern, while surfaces of the structure are functionalized with one or more click-chemistry compatible molecules each having one or more click-chemistry compatible functional groups. The structures may be formed from single- or dual-component resins, each having unique synthetic pathways. The resulting structures may be functionalized for utility in a wide range of applications by leveraging click chemistry to further functionalize the structure with organic additives also compatible with click-chemistry reaction schemes.

36 MATERIALS SCIENCE↗

Click-chemistry compatible structures, click-chemistry functionalized structures, and materials and methods for making the same

According to several embodiments, a composition of matter includes: a three-dimensional structure comprising photo polymerized molecules. At least some of the photo polymerized molecules further comprise one or more protected click-chemistry compatible functional groups; and at least portions of one or more surfaces of the three-dimensional structure are functionalized with one or more of the protected click-chemistry compatible functional groups. An additive manufacturing resin suitable for fabricating a click-chemistry compatible composition of matter includes: a photo polymerizable compound; and a click-chemistry compatible compound. A method of forming an additive manufacturing resin suitable for fabricating a click-chemistry compatible composition of matter includes: reacting a compound comprising a terminal alkyne group or a terminal azide group with a protecting reagent to form a protected reactive diluent precursor, reacting the precursor with a compound to form a protected reactive diluent; and mixing the protected reactive diluent with a photo polymerizable compound.

Campbell, Patrick↗

Microscopic deformation compatibility during monotonic loading in a Mg-Gd-Y alloy

Microscopic deformation compatibility is a key in achieving high ductility in polycrystalline magnesium alloys. This paper presents a grain-level compatibility investigation of Mg-Gd-Y alloy using in-situ tension in scanning electron microscopy (SEM) combined with electron back scattered diffraction (EBSD) and digital image correlation (DIC) techniques. The results show that strain amplitudes are not always higher in grains with high Schmid factors of basal slip. Thus, the Schmid law can hardly predict the strain amplitudes at grain level. In addition, the average intergranular strains are higher than the average intragranular strain and a strong surrounding effect grain-to-grain was found. A slip-transfer parameter m′, describing the surrounding effect, was used to evaluate the deformation compatibility. It is found that a high m′ value and a high Schmid factor of certain slip system in the adjacent grains would result in a good compatibility around grain boundaries and could accommodate higher local strains, which would improve the ductility of magnesium alloys. - Highlights: •Microstructure based DIC analyses have been performed on a Mg-Gd-Y alloy. •Strain amplitudes are higher at grain boundary areas than grain interiors. •Schmid Law is not applicable for predicting the strain amplitudes. •A geometric parameter m′ can effectively evaluate strain.

36 MATERIALS SCIENCE↗

Immune-compatible designs of semiconducting polymers for bioelectronics with suppressed foreign-body response

One of the greatest obstacles to achieving implantable electronics with long-term functionality and minimized inflammatory reactions is the immune-mediated foreign-body response (FBR). Recently, semiconducting polymers with mixed electron–ion conductivity have been demonstrated as promising candidates to achieve direct electrical interfacing on bio-tissues. However, there is limited understanding of their immune compatibility in vivo, and strategies for minimizing the FBR through molecular design remain underexplored. Here we introduce a set of molecular design strategies for enhancing the immune compatibility of semiconducting polymers. Specifically, we show that selenophene, when incorporated in the backbone, can mitigate the FBR by suppressing macrophage activation. In addition, side-chain functionalization with immunomodulatory groups decreases the FBR further by downregulating the expression of inflammatory biomarkers. Together, our synthesized polymers achieve suppression of the FBR by as much as 68% (as indicated by the collagen density). In the meantime, these immune-compatible designs still provide a high charge-carrier mobility of around 1 cm 2 V −1 s −1 . In conclusion, we anticipate that such immune-compatible design principles can be translated to a variety of conjugated polymers to suppress the FBR for implantable applications.

Li, Nan [University of Chicago, IL (United States)↗

Compatibility issues between electrodes and electrolytes in solid-state batteries

Remarkable success has been achieved in the discovery of ceramic alkali superionic conductors as electrolytes in solid-state batteries; however, obtaining a stable interface between these electrolytes and electrodes is difficult. Only limited studies on the compatibility between electrodes and solid electrolytes have been reported, partially because of the need for expensive instrumentation and special cell designs. Without simple yet powerful tools, these compatibility issues cannot be systematically investigated, thus hindering the generalization of design rules for the integration of solid-state battery components. Herein, we present a methodology that combines density functional theory calculations and simple experimental techniques such as X-ray diffraction, simultaneous differential scanning calorimetry and thermal gravimetric analysis, and electrochemistry to efficiently screen the compatibility of numerous electrode/electrolyte pairs. We systemically distinguish between the electrochemical stability of the solid-state conductor, which is relevant wherever the electrolyte contacts an electron pathway, and the electrochemical stability of the electrode/electrolyte interfaces. For the solid electrolyte, we are able to computationally derive an absolute thermodynamic stability voltage window, which is small for Na 3 PS 4 and Na 3 PSe 4 , and a larger voltage window which can be kinetically stabilized. The experimental stability, when measured with reliable techniques, falls between these thermodynamic and kinetic limits. Employing a Na solid-state system as an example, we demonstrate the efficiency of our method by finding the most stable system (NaCrO 2 |Na 3 PS 4 |Na–Sn) within a selected chemical space (more than 20 different combinations of electrodes and electrolytes). Important selection criteria for the cathode, electrolyte, and anode in solid-state batteries are also derived from this study. The current method not only provides an essential guide for integrating all-solid-state battery components but can also significantly accelerate the expansion of the electrolyte/electrode compatibility data.

25 ENERGY STORAGE↗

SU-E-T-655: Quantifying the Dosimetric Characteristics of a Calypso Compatible Radiotherapy Treatment Couch with Angular Transmission Functions

Purpose: To quantified the dosimetric characteristics of a Calypso compatible radiotherapy couch using continuously scanned transmission factor as a function of gantry angle. Methods: Radiation dose as a function of gantry angle was measured with an ionization chamber at the center of a 30 cm diameter cylindrical phantom placed on Qfix kVue Calypso compatible couch. A 3-D scanner was employed to continuously scan the dose during an arc rotation delivery. Nearly continuous transmission curves of 0.03° step size were obtained from IEC gantry angle 90° to180° for 6 MV and 15 MV photon beams at three couch longitudinal positions (due to longitudinally non-uniform shape of the couch rails) with rails both at the center and on sides. The transmission curves were evaluated to assess the attenuation by the couch. They were also compared to those of a carbon fiber couch top. Results: The scanned transmission curves of the Calypso comptible couch showed fine details of the couch transmission as a function of gantry angle. The attenuation by the couch varied from 2.4% to 12.9% for the 6 MV photo beam and from 1.8% to 8.9% for the 15 MV photon beam depending on the gantry angle. The attenuation by the flat couch top is only approximately 2 to 3%, but by the rail is much more significant. Because the rails are not uniformly shaped in the longitudinal direction, attenuation by the rail for the same gantry angle varied with the rail longitudinal position. The transmission curves of the carbon fiber couch top are nearly identical to those of the Calypso compatible couch top. Conclusion: The Calypso compatible couch attenuates radiation by 2.4%–12.9% and 1.8%–8.9% for 6 MV and 15 MV photon beams, respectively. The attenuation by the rails is much more significant than the flat couch top.

61 RADIATION PROTECTION AND DOSIMETRY↗

SU-F-I-15: Evaluation of a New MR-Compatible Respiratory Motion Device at 3T

Purpose: Recent advances in MRI-guided radiotherapy has inspired the development of MRI-compatible motion devices that simulate patient periodic motion in the scanner, particularly respiratory motion. Most commercial devices rely on non MR-safe ferromagnetic stepper motors which are not practical for regular QA testing. This work evaluates the motion performance of a new fully MRI compatible respiratory motion device at 3T. Methods: The QUASAR™ MRI-compatible respiratory motion phantom has been recently developed by Modus QA Inc., London, ON, Canada. The prototype is constructed from diamagnetic materials with linear motion generated using MRI-compatible piezoelectric motors that can be safely inserted in the scanner bore. The tumor was represented by a fillable sphere and is attached to the linear motion generator. The spherical tumor-representative and its surroundings were filled with different concentrations of MnCl2 to produce realistic relaxation times. The motion was generated along the longitudinal (H/F) axis of the bore using sinusoidal reference waveform (amplitude = 15 mm, frequency 0.25 Hz). Imaging was then performed on 3T Philips Achieva using a 32-channel cardiac coil. Fast 2D spoiled gradient-echo was used with a spatial resolution of 1.8 × 1.8 mm{sup 2} and slice thickness of 4 mm. The motion waveform was then measured on the resultant image series by tracking the centroid of the sphere through the time series. This image-derived measured motion was compared to the software-generated reference waveform. Results: No visible distortions from the device were observed on the images. Excellent agreement between the measured and the reference waveforms were obtained. Negligible motion was observed in the lateral (R/L) direction. Conclusion: Our investigation demonstrates that this piezo-electric motor design is effective at simulating periodic motion and is a potential candidate for MRI-radiotherapy respiratory motion simulation. Future work should focus on evaluating non-sinusoidal waveforms, fast 3D pulse sequences, and perform dosimetric QA.

60 APPLIED LIFE SCIENCES↗

Hydrogen Compatible Materials Workshop

This report serves as the proceedings of the Hydrogen Compatible Materials Workshop held virtually by Sandia National Laboratories on December 2-3, 2020. The purpose of the workshop was to assemble subject matter experts at Sandia and its national laboratory partners within the U.S. Department of Energy's (DOE) Hydrogen Materials Compatibility (H-Mat) Consortium with public and private stakeholders in the research, development and deployment of hydrogen technologies to discuss the topic of hydrogen compatible materials. This workshop was designed to build on past events and current research and development (R&D) efforts to develop a forward-looking vision that identifies gaps and challenges for the next decade. In particular, the workshop organizers sought to expand their understanding of hydrogen compatible materials needs for power, manufacturing and other industrial uses to enable deeper impact and widespread use of hydrogen while continuing to address open questions in hydrogen-powered transportation of concern to Original Equipment Manufacturers, hydrogen producers, materials & component suppliers and other private entities. The workshop was primarily organized as a series of panel-led discussions on the topics of hydrogen-enabled transportation, heating and power, and industrial uses. Each panel consisted of 2-3 subject matter experts who relayed their perspectives on a set of framing questions developed to facilitate discussion by the broader group of workshop participants. By the workshop's conclusion, the participants identified and prioritized a list of technical challenges for each panel topic where further R&D is warranted.

08 HYDROGEN↗

Compatibility of Elastomers with Polyoxymethylene Dimethyl Ethers and Blends with Diesel

Polyoxymethylene dimethyl ethers (PODEs) have shown promise as candidates for diesel fuel blendstocks due to their low sooting tendency, high cetane number, and diesel-comparable boiling point range. However, there is a lack of literature regarding compatibility of PODEs with common automotive elastomers, which would be a prerequisite to their adoption into the marketplace. To address this need, an exposure study and complementary solubility analysis were undertaken. A commercially available blend of PODEs with polymerization degree ranging from 3 to 6 was blended with diesel certification fuel at 0, 33, 50, 67, at 100% by mass. Elastomer coupons were exposed to the various blends for a period of 4 weeks and evaluated for volume swell. The elastomer materials included multiple fluoroelastomers (Viton and fluorosilicone) and acrylonitrile butadiene rubbers (NBR), as well as neoprene, polyurethane, epichlorohydrin (ECO), PVC-nitrile blend (OZO), ethylene propylene diene monomer (EPDM), styrene-butadiene rubber (SBR), and silicone. The exposure results indicated overall poor compatibility for PODE, with every elastomer except for fluorosilicone exhibiting greater than 30% volume swell at the 33% blend level. The general trend across the elastomers was either a consistent increase in volume swell with PODE concentration, or maximum in volume swell at an intermediate blend fraction. One notable exception is EPDM, which is not generally compatible with diesel fuel and which exhibited a reduction in volume swell with increasing PODE concentration. The same elastomers and PODE/diesel blends were evaluated using Hansen solubility parameter analysis, which predicted similar trends to the exposure study with the exception of ECO. From these results, we conclude that adoption of PODEs as a diesel fuel blendstock will require either the development of specialized elastomers, or that the blend fraction be kept to a low level to maintain compatibility with existing elastomers.

42 ENGINEERING↗

Strain compatibility assessment for SRB sprayable ablator MSA-1

Tensile and compressive strain compatibility testing was performed on as-sprayed samples of the Shuttle Solid Rocket Booster external ablator material, MSA-1. Strain gages on the aluminum substrate were used to monitor strain. Strain compatibility was determined as the percent strain in the substrate at first visual evidence of MSA-1 failure. The 1/8-in. MSA-1, baselined for large areas of the SRB external skin, was characterized by a strain compatibility of 1.5 to 1.8 percent, which far exceeded the yield range of the metal substrate. Thicker MSA-1 applications (1.4 to 3/8 in.) were characterized by a lower level of strain compatibility, which appeared to be a manifestation of application limitations.

Patterson, W. J.↗

Improved method for stress and compatibility analysis of multicomponent rotating systems

An improved method of analyzing multicomponent rotating assemblies for the determination of operating stresses and component compatibility has been developed. In this method, a single finite element model is developed which contains all of the separate components in the rotating assembly. This is made possible by using gap elements to simulate the contact surfaces between components. The MARC finite element computer program is then used to perform the analysis. This improved method is less time consuming and more reliable than the conventional method of analyzing such systems. Results are presented for two different stress-compatibility analyses of a six-component axial flow compressor rotor. The results for the previously used flexibility analysis method are compared with those for the improved analysis method. The stresses predicted by each method compare quite well with each other. The predictions of the component compatibility, as well as the magnitude of the forces at the contact surfaces, also compare well for these two analysis procedures. It is therefore recommended that the improved analysis method be used to determine the stress-compatibility characterstics of multicomponent rotating systems.

Carek, Gerald A.↗

General purpose program to generate compatibility matrix for the integrated force method

An efficient procedure for obtaining the compatibility conditions of finite-element models involves the generation of both field and compatibility conditions from deformation-displacement relations, using (1) the compatibility bandwidth, and (2) the node-determinacy concept. A computer program thus structured will generate sparse and banded compatibility conditions for a structure that is idealized by the finite elements.

Nagabhusanam, J.↗

Development and Implementation of Environmentally Compatible Solid Film Lubricants

Multi-body launch vehicles require the use of Solid Film Lubricants (SFLs) to allow for unrestricted relative motion between structural assemblies and components during lift off and ascent into orbit. The Space Shuttle Solid Rocket Booster (SRB), uses a dual coat, ceramic-bonded high temperature SFL in several locations such as restraint hardware between the SRB aft skirt and the Mobile Launch Platform (MLP), the aft SRB/External Tank (ET) attach struts, and the forward skirt SRB/ET attach ball assembly. The proposed National Launch System (NLS) may require similar applications of SFLs for attachment and restraint hardware. A family of environmentally compatible nonlead/antimony bearing alternative SFLs have been developed including a compatible repair material. In addition, commercial applications for SFLs on transportation equipment, all types of lubricated fasteners, and energy related equipment allow for wide usage of these new lubricants. The new SFLs named BOOSTERLUBE is a family of single layer thin film (0.001 inch maximum) coatings that are a unique mixture of non-hazardous pigments in a compatible resin system that allows for low temperature curing (450 F). Significant savings in energy and processing time as well as elimination of hazardous material usage and disposal would result from the non-toxic onestep SFL application. Compatible air-dry field repair lubricants will help eliminate disassembly of launch vehicle restraint hardware during critical time sensitive assembly operations.

Novak, Howard L.↗

Development and Implementation of Environmentally Compatible Solid Film Lubricants

Multi-body launch vehicles require the use of Solid Film Lubricants (SFLs) to allow for unrestricted relative motion between structural assemblies and components during lift-off and ascent into orbit. The Space Shuttle Solid Rocket Booster (SRB), uses a dual coat, ceramic-bonded high temperature SFL in several locations such as restraint hardware between the SRB aft skirt and the Mobile Launch Platform (MLP), the aft SRB/External Tank (ET) attach struts, and the forward skirt SRB/ET attach ball assembly. Future launch systems may require similar applications of SFLs for attachment and restraint hardware. A family of environmentally compatible non-lead/antimony bearing alternative SFLs have been developed including a compatible repair material. In addition, commercial applications for SFLs on transportation equipment, all types of lubricated fasteners, and energy related equipment allow for wide usage's of these new lubricants. The new SFLs trade named BOOSTERLUBE is a family of single layer thin film (0.001 inch maximum) coatings that are a unique mixture of non-hazardous pigments in a compatible resin system that allows for low temperature curing (450 F). Significant savings in energy and processing time as well as elimination of hazardous material usage and disposal would result from the non-toxic one-step SFL application. Compatible air-dry field repair lubricants will help eliminate disassembly of launch vehicle restraint hardware during critical time sensitive assembly operations.

Novak, Howard L.↗