Non-contact measurements of creep properties of niobium at 1985 °C

Lee, J; Wall, James A.; Rogers, J. R.; Rathz, T. J.; Choo, Hahn; Liaw, Peter K.; Hyers, R. W.

doi:10.1088/0957-0233/26/1/015901

Cited by 5 publications

(3 citation statements)

References 37 publications

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“…As such intense beams illuminate off-center of the sample, the sample can rotate by photon pressure of the laser beams. For example, a solid, 2 mm diameter sample of Nb, was capable of accelerating to 4880 revolutions per second (rps) when heated with a 200 W Nd:YAG laser at 2258 K over 420 min in ESL [36]. Considering the similar rate of acceleration (∼700 rps), an ESL sample heated over 3000 K for 10 min should gain a rotational speed in the order of ∼100 rps.…”

Section: Evaluation Of Shape Deformation By Local Heatingmentioning

confidence: 99%

Precise density measurement and its uncertainty evaluation for refractory liquid metals over 3000 K using electrostatic levitation

et al. 2022

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Accurate density measurement of molten refractory metals over 3000 K is very challenging, which is difficult to be achieved with conventional methods. Although containerless techniques have been the most effective and well-established methods to measure the density of molten metals at such high temperatures, a large discrepancy in the containerlessly measured density values has been reported. Here, we identify the uncertainty factors of the density measurement and their influence on the measured density of molten refractory metals over 3000 K using an electrostatic levitator (ESL). We find that intensely focused laser beams can cause rotation-induced deformation of a levitated droplet and thus the large uncertainty in the measured density. Moreover, the combination of sample rotation and precession seriously affects the measurements of density and temperature dependence of density (i.e., volume thermal expansion). By minimizing such rotation and precession, we successfully measure the density and volume expansion coefficient of refractory liquids (tantalum, molybdenum, and niobium) with the significantly improved reproducibility and accuracy, and evaluate the uncertainties associated with the density measurement using ESL.

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Section: Evaluation Of Shape Deformation By Local Heatingmentioning

confidence: 99%

Precise density measurement and its uncertainty evaluation for refractory liquid metals over 3000 K using electrostatic levitation

et al. 2022

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“…This enables supercooling of liquids often by several hundreds of degrees below their equilibrium melting points. These systems have been used to measure thermal expansion, [37][38][39] phase transformations, 37,38,40 creep, 41,42 melting points, [43][44][45] surface tension, 33,[46][47][48][49][50] and viscosities 32,[45][46][47][48][49] at high temperatures. The systems that are currently in operation have been optimized for either oxide or metallic materials, and the highest reported temperatures are ∼3773 K 51 on oxide systems in oxygen using aerodynamic levitation and ∼3673 K on non-oxide systems in inert atmospheres 41,52 using ESL.…”

Section: Introductionmentioning

confidence: 99%

Environmental conical nozzle levitator equipped with dual wavelength lasers

Thorpe,

Li,

Weber

et al. 2023

J Am Ceram Soc.

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The environmental conical nozzle levitator (E‐CNL) with dual‐wavelength lasers is an extreme environment materials characterization system that was designed to investigate ultra‐high‐temperature materials: refractory metals, oxides, carbides, and borides above 3000 K in a controlled atmosphere. This article details the characterizations using this system to establish its high‐temperature capabilities and to outline ongoing work on materials under extreme conditions. The system has been used to measure the melting point of several oxide materials (TiO2, Tm = 2091 ± 3 K; Al2O3, Tm = 2310 3 K; ZrO2, Tm = 2984 31 K; and HfO2, Tm = 3199 ± 45 K) and several air‐sensitive refractory metals (Ni, Tm = 1740 K; Ti, Tm = 1983 K; Nb, Tm = 2701 K; and Ta, Tm = 3368 K—note: mean ± standard deviation) during levitation which matched literature values within 0.17–2.43 % demonstrating high accuracy and precision. This containerless measurement approach is critical for probing properties without container‐derived contamination, and dual‐wavelength laser heating is essential to heat both relatively poor electrical conductors (some refractory metals and carbides) and insulators (oxides). The highest temperature achieved utilizing both lasers in these experiments was ∼4250 ± 34 K on a 76.6 mg, molten HfO2 sample using a normal spectral emissivity of 0.91. Stable levitation was demonstrated on spherical samples (yttria‐stabilized zirconia) while adjusting levitation gas composition from pure oxygen to pure argon, verifying atmospheric control up to 3173 K on solid or molten samples. These successes demonstrate the viability of in situ high‐temperature environmentally controlled studies potentially up to 4000 K on all classes of ultra‐high‐temperature materials in one system. These measurements highlight the E‐CNL system will be essential for the development of next‐generation ultra‐high‐temperature materials for hypersonic platforms, nuclear fission and fusion, and space exploration.

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“…The emissivity input of the pyrometer is adjusted until the melt plateau is observed at the correct temperature. Additional capabilities of the MSFC ESL lab include non-contact creep strength measurement [12,13], triggered nucleation [14], and a rapid quench system [15]. …”

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confidence: 99%

Experiments Using a Ground-Based Electrostatic Levitator and Numerical Modeling of Melt Convection for the Iron-Cobalt System in Support of Space Experiments

Lee¹,

SanSoucie

2017

JOM

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Materials research is being conducted using an electromagnetic levitator installed in the International Space Station. Various metallic alloys were tested to elucidate unknown links among the structures, processes, and properties. To accomplish the mission of these space experiments, several ground-based activities have been carried out. This paper presents some of our ground-based supporting experiments and numerical modeling efforts. Mass evaporation of Fe50Co50, one of the flight compositions, was predicted numerically and validated by the tests using an electrostatic levitator (ESL). The density of various compositions within the Fe-Co system was measured with ESL. These results serve as reference data for the space experiments. The convection inside a electromagneticallylevitated droplet was also modeled to predict the flow status, shear rate, and convection velocity under various process parameters, which is essential information for designing and analyzing the space experiments of some flight compositions influenced by convection. INTRODUCTIONSince 2015, several materials experiments have been performed using the materials science laboratory electromagnetic levitator (MSL-EML) aboard the International Space Station (ISS). More than 50 principal investigators from 13 different countries have been participating in this space program. Thermophysical properties, transport phenomena, and glass/quasicrystal formation of various alloys are being studied using MSL-EML. To increase the chance of success in the space experiments, the team has meticulously planned and prepared for their science experiments. The safety aspects, mass evaporation [1] and thermophysical properties [2-4] of each sample have been measured as part of the ground support program.The measurement of mass evaporation is important. Evaporation often causes composition shifts of tested alloys resulting from preferential evaporation of volatile species. Such composition shifts can be reduced by limiting superheating and time for thermal hold during property measurements. On the other hand, evaporated materials may end up as aerosols, which can be hazardous to the health of the astronauts. Otherwise the evaporated materials will deposit on the optics, obscuring measurements, or on the coils. Excessive coil deposition can cause flaking of deposited materials, cross-contamination, short circuiting, and arcing. Each batch has 18 samples, and the amount of mass evaporation of each sample is different depending on the composition and thermal history. After discussion among scientists, the thermal cycles of each samples are adjusted such that the total amount of mass evaporation does not exceed a designated value.For flight samples whose internal convection is of interest, numerical models were developed [5] and used [6]. The developed numerical models have been used to predict the convection status under an anticipated combination of process parameters. The status of convection affects phase selection during solidification of metal alloys which exhibit ...

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Non-contact measurements of creep properties of niobium at 1985 °C

Cited by 5 publications

References 37 publications

Precise density measurement and its uncertainty evaluation for refractory liquid metals over 3000 K using electrostatic levitation

Precise density measurement and its uncertainty evaluation for refractory liquid metals over 3000 K using electrostatic levitation

Environmental conical nozzle levitator equipped with dual wavelength lasers

Experiments Using a Ground-Based Electrostatic Levitator and Numerical Modeling of Melt Convection for the Iron-Cobalt System in Support of Space Experiments

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