Design and fabrication of ceramic beads by the vibration method

Santos, Christian J. Espinoza; Nelson, Arif Z.; Mendoza, E.U.; Ewoldt, Randy H.; Kriven, Waltraud M.

doi:10.1016/j.jeurceramsoc.2015.05.018

Cited by 11 publications

(9 citation statements)

References 35 publications

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“…The hafnium tantalate powders was processed into polycrystalline sintered spheroids, 2‐3 mm in diameter, by means of a vibrating table method . Ceramic slurries were prepared from 87 vol% hafnium tantalate powder having a 200 μm particle size, 5 vol% methyl cellulose binder (Sigma‐Aldrich), 1 vol% Darvin ® dispersant (Vanderbilt Company, Norwalk, CT) and 7 vol% water.…”

Section: Methodsmentioning

confidence: 99%

“…This slurry was vibrated at a frequency of 70 Hz in a cubed‐walled container having 30 mm dimensions for approximately 5 minutes, or until the beads had sufficient green strength. This method is described in more detail by Santos et al . The resulting spherical beads were heat treated at 1300°C for 6 hours at a heating rate of 2°C/min and cooling rate of 8°C/min.…”

Section: Methodsmentioning

confidence: 99%

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In‐situ determination of the HfO₂–Ta₂O₅‐temperature phase diagram up to 3000°C

et al. 2019

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The previously unknown experimental HfO 2 -Ta 2 O 5 -temperature phase diagram has been elucidated up to 3000°C using a quadrupole lamp furnace and conical nozzle levitator system equipped with a CO 2 laser, in conjunction with synchrotron X-ray diffraction. These in-situ techniques allowed the determination of the following: (a) liquidus, solidus, and invariant transformation temperatures as a function of composition from thermal arrest experiments, (b) determination of equilibrium phases through testing of reversibility via in-situ X-ray diffraction, and (c) molar volume measurements as a function of temperature for equilibrium phases. From these, an experimental HfO 2 -Ta 2 O 5 -temperature phase diagram has been constructed which is consistent with the Gibbs Phase Rule.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

In‐situ determination of the HfO₂–Ta₂O₅‐temperature phase diagram up to 3000°C

et al. 2019

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“…This chamber is also equipped with a pressure relief system and rapid chamber filling valve. Thus, refractory metals, carbides, and borides can be formed into beads 60,61 and levitated 43 in an inert gas stream, preventing sample-container reactions.…”

Section: E-cnl Equipped With Dual-wavelength Lasers Instrument Designmentioning

confidence: 99%

“…62 The vibrating table method involves forming a slurry using powder, a binder (methyl cellulose), a dispersant (Ammonium Polymethacrylate Darvan C-N), and a solvent (water) and placing this slurry on a vibrating table with enclosed walls at ∼70 Hz. 60,61 This causes the slurry to bounce and deform, thereby forming a spherical shape that requires drying and calcination. Gel casting involves forming a slurry with powder, a polymer, a cross-linking agent, and water which is drop-cast into a hot silicone oil with a surfactant.…”

Section: E-cnl Equipped With Dual-wavelength Lasers Instrument Designmentioning

confidence: 99%

“…Key flow characteristics of aerodynamic levitation were analyzed by Nordine and Atkins. 63 For more details regarding these processing conditions, please refer to references: 39,[60][61][62][63] . Ceramic solid oblate spheroids at ∼3200 K can have temperature gradients up to ∼500 K/mm (depending on processing), which can be reduced to ∼15 K/mm if the sample is a perfect dense sphere that rotates on all axes, distributing the heat over the materials surface.…”

Section: E-cnl Equipped With Dual-wavelength Lasers Instrument Designmentioning

confidence: 99%

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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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