Ultrasonic temperature measuring device Fifth quarterly progress report
Refractory material irradiation, sensor studies, and sheath applications for development of ultrasonic temperature measuring device
RADIATION EFFECT↗
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Airframe materials for HSR
Vugraphs are presented to show the use of refractory materials for the skin of the High speed Civil Transport (HSCT). Examples are given of skin temperature ranges, failure mode weight distribution, tensile properties as a function of temperature, and components to be constructed from composite materials. The responsibilities of various aircraft companies for specific aircraft components are defined.
Bales, Thomas T.↗
A Noncontact Measurement Technique for the Density and Thermal Expansion Coefficient of Solid and Liquid Materials
A noncontact measurement technique for the density and the thermal expansion refractory materials in their molten as well as solid phases is presented. This technique is based on the video image processing of a levitated sample. Experiments were performed using the high-temperature electrostatic levitator (HTESL) at the Jet Propulsion Laboratory in which 2-3 mm diameter samples can be levitated, melted, and radiatively cooled in a vacuum. Due to the axisymmetric nature of the molten samples when levitated in the HTESL, a rather simple digital image analysis can be employed to accurately measure the volumetric change as a function of temperature. Density and the thermal expansion coefficient measurements were made on a pure nickel sample to test the accuracy of the technique in the temperature range of 1045-1565 C. The result for the liquid phase density can be expressed by p = 8.848 + (6.730 x 10(exp -4)) x T (degC) g/cu cm within 0.8% accuracy, and the corresponding thermal expansion coefficient can be expressed by Beta=(9.419 x 10(exp -5)) - (7.165 x 10(exp -9) x T (degC)/K within 0.2% accuracy.
Chung, Sang K.↗
Additive Manufacture of Refractory Metals for Aerospace Applications
High temperature refractory metals are required for a number of high temperature propulsion applications. Refractory metals are expensive, difficult to manufacture with high buy-to-fly ratios, and few vendors. Additive manufacture (AM) is used to produce C103, Molybdenum (Mo), and Tungsten (W) reaction chamber and thrust stand-off as well as Iridium ultra-fine lattice catalysts for integration into 1 N green propulsion thrusters. Refractory AM is in development and like traditional AM alloys requires substantial post-processing to include powder heat treatment, surface finish enhancement, inspection, and machining before placed in service. The combination of limited feedstock sources, high temperature processing, oxygen sensitivity, fracture prone nature, and need for elevated temperature mechanical testing limit the number of qualified facilities capable of post-processing AM refractory materials, which add to cost and schedule constraints. However, properly implemented refractory metal AM can overcome existing manufacture limitations by greatly increasing design flexibility, new material options, reduced price, decreased lead-time, and leverage the ever growing AM commercial supply base.
Refractory metal additive manufacture↗
Additive Manufacture of Refractory Metals for Aerospace Applications
High temperature refractory metals are required for a number of high temperature propulsion applications. Refractory metals are expensive, difficult to manufacture with high buy-to-fly ratios, and few vendors. Additive manufacture (AM) is used to produce C103, Molybdenum (Mo), and Tungsten (W) reaction chamber and thrust stand-off as well as Iridium ultra-fine lattice catalysts for integration into 1 N green propulsion thrusters. Refractory AM is in development and like traditional AM alloys requires substantial post-processing to include powder heat treatment, surface finish enhancement, inspection, and machining before placed in service. The combination of limited feedstock sources, high temperature processing, oxygen sensitivity, fracture prone nature, and need for elevated temperature mechanical testing limit the number of qualified facilities capable of post-processing AM refractory materials, which add to cost and schedule constraints. However, properly implemented refractory metal AM can overcome existing manufacture limitations by greatly increasing design flexibility, new material options, reduced price, decreased lead-time, and leverage the ever growing AM commercial supply base.
Refractory metal additive manufacture↗
Novel Ceramic Dispersion Strengthened Refractory Metals for Improved Printability and Properties
Refractory metals and alloys are of major interest for nuclear fusion systems, space nuclear power and propulsion, and hypersonic applications due to their desirable properties at elevated temperatures (>1500°C). Limitations of refractory materials include their low ductility, poor oxidation resistance, and high manufacture cost using traditional techniques. Additive manufacturing (AM) can reduce material waste associated with manufacture, but AM fabrication is impacted by the brittleness of these refractory metals, resulting in excessive cracking during printing. Cracking reduces the effectiveness of hot isostatic pressing (HIP) which is commonly used to improve density and mechanical properties of AM components. The goal of this work is to improve refractory metal printability without majorly affecting the material properties which are the main reason these materials are used. Ceramic nanoparticles have been shown to help improve material properties after heat treatment. Results will be shown that demonstrate the effectiveness of adding nanoparticles to refractory metals. Additionally, there will be discussion regarding how these nanoparticles change the effect of heat treatments such as HIP compared with the AM pure metal samples.
Carly J. Romnes↗
NASA Space Engineering Research Center for Utilization of Local Planetary Resources
In the processing of propellants, volatiles, and metals subject area, the following topics are discussed: reduction of lunar regolith; reduction of carbon dioxide; and reduction of carbonaceous materials. Other areas addressed include: (1) production of structural and refractory materials; (2) resource discovery and characterization; (3) system automation and optimization; and (4) database development. The majority of these topics are discussed with respect to the development of lunar and mars bases. Some main topics of interest include: asteroid resources, lunar resources, mars resources, materials processing, construction materials, propellant production, oxygen production, and space-based oxygen production plants.
Ramohalli, Kumar↗
Shock-wave properties and high-pressure equations of state of geophysically important materials
Shock wave (Hugoniot), shock temperature, and release data are presented for several geophysically important, refractory materials. A sensitive multichannel optical pyrometer was developed to measure shock temperatures (2500 to 5600 K at pressures from 48 to 117 GPa) in anorthite (CaAl2Si2O8) glass. Shock temperatures of 3750 to 6000 K at pressures from 140 to 182 GPa were measured in calcium oxide (CaO). Temperature data were used to constrain the energetics of the B1-B2 phase transition at 70 GPa in CaO, and to construct a finite strain equation of state for CaO consistent with previous Hugoniot data. The CaO equation of state was used with equation of state parameters of other oxides to construct a theoretical mixed oxide Hugoniot of anorthite, which is in agreement with new Hugoniot data above about 50 GPa, determined using experimental techniques developed. The mixed oxide model, however, overestimates the shock temperatures, and does not accurately predict measured release paths.
Boslough, M. B.↗
Thin-Film Ceramic Thermocouples Fabricated and Tested
The Sensors and Electronics Technology Branch of the NASA Glenn Research Center is developing thin-film-based sensors for surface measurement in propulsion system research. Thin-film sensors do not require special machining of the components on which they are mounted, and they are considerably thinner than wire- or foil-based sensors. One type of sensor being advanced is the thin-film thermocouple, specifically for applications in high-temperature combustion environments. Ceramics are being demonstrated as having the potential to meet the demands of thin-film thermocouples in advanced aerospace environments. The maximum-use temperature of noble metal thin-film thermocouples, 1500 C (2700 F), may not be adequate for components used in the increasingly harsh conditions of advanced aircraft and next-generation launch vehicles. Ceramic-based thermocouples are known for their high stability and robustness at temperatures exceeding 1500 C, but are typically in the form of bulky rods or probes. As part of ASTP, Glenn's Sensors and Electronics Technology Branch is leading an in-house effort to apply ceramics as thin-film thermocouples for extremely high-temperature applications as part of ASTP. Since the purity of the ceramics is crucial for the stability of the thermocouples, Glenn's Ceramics Branch and Case Western Reserve University are developing high-purity ceramic sputtering targets for fabricating high-temperature sensors. Glenn's Microsystems Fabrication Laboratory, supported by the Akima Corporation, is using these targets to fabricate thermocouple samples for testing. The first of the materials used were chromium silicide (CrSi) and tantalum carbide (TaC). These refractory materials are expected to survive temperatures in excess of 1500 C. Preliminary results indicate that the thermoelectric voltage output of a thin-film CrSi versus TaC thermocouple is 15 times that of the standard type R (platinum-rhodium versus platinum) thermocouple, producing 20 mV with a 200 C temperature gradient. The photograph on the left shows the CrSi-TaC thermocouple in a test fixture at Glenn, and the resulting output signal is shown on the right. The temperature differential across the sample, from the center of the sample inside the oven to the sample mount outside the oven, is measured using a type R thermocouple on the sample.
Wrbanek, John D.↗
High performance structural laminate composite material for use to 1000.degree. F. and above, apparatus for and method of manufacturing same, and articles made with same
A novel materials technology has been developed and demonstrated for providing a high modulus composite material for use to 1000.degree. F. and above. This material can be produced at 5-20% of the cost of refractory materials, and has higher structural properties. This technology successfully resolves the problem of thermal shock or ply lift, which limits traditional high temperature laminates (such as graphite/polyimide and graphite/phenolic) to temperatures of 550-650.degree. F. in thicker (0.25 and above) laminates. The technology disclosed herein is an enabling technology for the nose for the External Tank (ET) of the Space Shuttle, and has been shown to be capable of withstanding the severe environments encountered by the nose cone through wind tunnel testing, high temperature subcomponent testing, and full scale structural, dynamic, acoustic, and damage tolerance testing.
Seal, Ellis C.↗
Refractories Keep Silicon Crystals Pure
Formation of carbon monoxide gas is prevented by a linear of refractory material free of elemental carbon. For pressures above about 4 torr, silicon carbide can be used as refractory liner. The problem of carbide contamination can arise in crystal growth of any material that forms a carbide more stable than carbon monoxide. Prevention in such cases is possible by using noncarbon refractories in place of graphite.
Schmid, F.↗
Improved Rare-Earth Emitter Hollow Cathode
An improvement has been made to the design of the hollow cathode geometry that was created for the rare-earth electron emitter described in Compact Rare Earth Emitter Hollow Cathode (NPO-44923), NASA Tech Briefs, Vol. 34, No. 3 (March 2010), p. 52. The original interior assembly was made entirely of graphite in order to be compatible with the LaB6 material, which cannot be touched by metals during operation due to boron diffusion causing embrittlement issues in high-temperature refractory materials. Also, the graphite tube was difficult to machine and was subject to vibration-induced fracturing. This innovation replaces the graphite tube with one made out of refractory metal that is relatively easy to manufacture. The cathode support tube is made of molybdenum or molybdenum-rhenium. This material is easily gun-bored to near the tolerances required, and finish machined with steps at each end that capture the orifice plate and the mounting flange. This provides the manufacturability and robustness needed for flight applications, and eliminates the need for expensive e-beam welding used in prior cathodes. The LaB6 insert is protected from direct contact with the refractory metal tube by thin, graphite sleeves in a cup-arrangement around the ends of the insert. The sleeves, insert, and orifice plate are held in place by a ceramic spacer and tungsten spring inserted inside the tube. To heat the cathode, an insulating tube is slipped around the refractory metal hollow tube, which can be made of high-temperature materials like boron nitride or aluminum nitride. A screw-shaped slot, or series of slots, is machined in the outside of the ceramic tube to constrain a refractory metal wire wound inside the slot that is used as the heater. The screw slot can hold a single heater wire that is then connected to the front of the cathode tube by tack-welding to complete the electrical circuit, or it can be a double slot that takes a bifilar wound heater with both leads coming out the back. This configuration replaces the previous sheathed heater design that limited the cycling-life of the cathode.
Goebel, Dan M.↗
Evaluation of oxidation resistant nonmetallic materials at 1204 C (2200 F) in a Mach 1 burner
Specimens of 23 oxidation resistant, nonmetallic, refractory materials were systematically exposed in a high gas velocity burner to simulate a turbine engine environment. Isothermal and cyclic tests were conducted at a specimen temperature of 2200F which resulted from exposure to Mach 1 or Mach 0.5 hot gas streams. Specimen behavior was judged on the basis of failure mode, appearance, and weight change. SiC and Si3N4 exhibited the most promising behavior surviving all exposures including Mach 1 for 120 cycles (10 hr). Major failure modes identified for other materials were thermal shock, thermal fatigue, and mechanical failure due to gas loading.
Sanders, W. A.↗
Influence of deflocculant on the isoelectric point of refractory powders: Considerations on the action of deflocculant
Isoelectric point changes in suspensions of refractory materials vis-a-vis the role of deflocculants used in monolithic refractories were investigated by considering the mineral compositions and adsorbed ions in four kinds of clay. Three types of curves represented the relation between the isoelectric point and the deflocculant. The surface charge of clay particles in the suspensions became negative as a result of the deflocculant, since the isoelectric point of suspensions decreased as the deflocculant was added. The isoelectric point changes of calcined alumina were also compared with those of the clays, and a similar phenomenon was observed, except that the deflocculant dispersed the calcined alumina better than it did the clays. A simple model was used to analyze the results.
Naruse, Y.↗
The Organic Component of Interstellar Dust
The distribution, chemical structure, and formation of organic matter in the interstellar medium are important to our understanding of the overall evolution of dust. The exchange of dust between the dense and diffuse interstellar medium, and the effects of processing on dust within dense clouds will affect the inventory of material available for incorporation into newly forming star and planetary systems. Observational ground-based studies have confirmed the widespread distribution of the 3.4 pm absorption band attributed to aliphatic hydrocarbons in the diffuse interstellar medium of our own galaxy, and in the dusty spectra of a few nearby galaxies, while space based observations from IS0 probed the signatures of corresponding mid-infrared features. Laboratory experiments which utilize both thermal processes and energetic processing by high energy photons and cosmic rays, produce candidate materials which offer close matches to the observed diffuse interstellar medium and extragalactic hydrocarbon absorption features. Through an analysis of the 4000 to 1000 cm (2.5 to 10 micrometers) region of the spectrum of diffuse interstellar medium (DISM) dust compared with the spectra of thirteen chemical entities produced in the laboratory which serve as analogs to the interstellar material, significant constraints have been placed on the applicability of proposed candidate materials to explain the interstellar features. The results indicate that the organic refractory material in the diffuse interstellar medium is predominantly hydrocarbon in nature, possessing little nitrogen or oxygen, with the carbon distributed between the aromatic and aliphatic forms. Long alkane chains H3C-(CH2),- with n much greater than 4 or 5 are not major constituents of this material. Comparisons to laboratory analogs indicate the DISM organic material resembles plasma processed pure hydrocarbon residues much more so than energetically processed ice residues. This result is consistent with a birthsite for the carrier of the 3.4 micrometers band in the outflow region of evolved carbon stars. Comparisons of dust from our own galaxy with that of distant galaxies suggests that the organic component of interstellar dust is widespread and may be an important universal reservoir of prebiotic organic carbon.
Pendleton, Yvonne↗
Practical method of diffusion-welding steel plate in air
Method is ideal for critical service requirements where parent metal properties are equaled in notch toughness, stress rupture and other characteristics. Welding technique variations may be used on a variety of materials, such as carbon steels, alloy steels, stainless steels, ceramics, and reactive and refractory materials.
Holko, K. H.↗
Materials degradation in low earth orbit (LEO); Proceedings of the Symposium, 119th Annual Meeting of the Minerals, Metals, and Materials Society, Anaheim, CA, Feb. 17-22, 1990
The current understanding of the effect of space environment on materials and the development of protective coatings is examined in reviews and reports. Consideration is given to hyperthermal atomic oxygen reactions, the effect of atomic oxygen on altered and coated Kapton surfaces for spacecraft applications in LEO, silicon dioxide space coatings studied ellipsometrically, atomic oxygen effects on spacecraft materials, atomic oxygen beam source for erosion simulation, and atomic oxygen effects on refractory materials. Particular attention is given to ellipsometric analysis of materials degradation in space, studies of the interaction of 8 km/s oxygen atoms with selected materials, characterization and calibration of the EOIM-III flight mass spectrometer in a high velocity oxygen atom beam, the reaction efficiency of thermal energy oxygen atoms with polymeric materials, and effects of simulated space environments on the properties of selected materials.
Srinivasan, V.↗