scholarly journals Measurements of Density of Liquid Oxides with an Aero-Acoustic Levitator

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 822
Author(s):  
Sergey V. Ushakov ◽  
Jonas Niessen ◽  
Dante G. Quirinale ◽  
Robert Prieler ◽  
Alexandra Navrotsky ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
High Speed ◽  
Space Station ◽  
Rare Earth Oxide ◽  
Mixing Models ◽  
Melting Temperatures ◽  
Liquid Oxide ◽  
Density Values ◽  
Acoustic Levitator ◽  
Oxide Melts

Densities of liquid oxide melts with melting temperatures above 2000 °C are required to establish mixing models in the liquid state for thermodynamic modeling and advanced additive manufacturing and laser welding of ceramics. Accurate measurements of molten rare earth oxide density were recently reported from experiments with an electrostatic levitator on board the International Space Station. In this work, we present an approach to terrestrial measurements of density and thermal expansion of liquid oxides from high-speed videography using an aero-acoustic levitator with laser heating and machine vision algorithms. The following density values for liquid oxides at melting temperature were obtained: Y2O3 4.6 ± 0.15; Yb2O3 8.4 ± 0.2; Zr0.9Y0.1O1.95 4.7 ± 0.2; Zr0.95Y0.05O1.975 4.9 ± 0.2; HfO2 8.2 ± 0.3 g/cm3. The accuracy of density and thermal expansion measurements can be improved by employing backlight illumination, spectropyrometry and a multi-emitter acoustic levitator.

Dynamics of Machine Tool Spindle/Bearing Systems Under Thermal Growth

1997 ◽  
Vol 119 (4) ◽  
pp. 875-882 ◽  
Author(s):  
Bert R. Jorgensen ◽  
Yung C. Shin
Keyword(s):  
Thermal Expansion ◽  
Dynamic Response ◽  
Heat Generation ◽  
High Speed ◽  
Transfer Model ◽  
Good Prediction ◽  
High Speeds ◽  
Spindle Bearing ◽  
Thermal Growth ◽  
Bearing Stiffness

Increased use of high-speed machining creates the need to predict spindle/bearing performance at high speeds. Spindle dynamic response is a function of the nonlinear bearing stiffness. At high speeds, thermal expansion can play an important role in bearing stiffness. A complete bearing load-deflection analysis including thermal expansion is derived and is coupled with an analysis of spindle dynamic response. Steady-state temperature distribution is found from heat generation at the contact point and from a quasi three-dimensional heat transfer model. Numerical solutions give a good prediction of thermal growth and heat generation in the bearing. Predicted high-speed spindle frequencies show good agreement with experimentation. The effects of loading condition and bearing material type on bearing stiffness are also shown.

The Research of Spraying SiC/Cu Electronic Packaging Composites

2011 ◽  
Vol 284-286 ◽  
pp. 620-623
Author(s):  
Ming Hu ◽  
Jing Gao ◽  
Yun Long Zhang
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Process Parameters ◽  
Electronic Packaging ◽  
High Speed ◽  
Volume Fraction ◽  
Flame Spraying ◽  
Packaging Materials ◽  
Excellent Performance ◽  
Chemical Plating

The SiC/Cu electronic packaging composites with excellent performance were successfully prepared by the chemical plating copper on the surface of SiC powders and high-speed flame spraying technology. The results showed that the homogeneous dense coated layers can be obtained on the surface of SiC powder by optimizing process parameters. The volume fraction of SiC powders in the composites could significantly increase and figure was beyond 55vol% after spraying Copper. The SiC and Cu were the main phases in the spraying SiC/Cu electronic packaging composite, at the same time Cu2O can be tested as the trace phase. The interface combination properties of SiC/Cu in the hot-pressed samples can obviously improve. The thermal expansion coefficient and thermal conductivity of SiC/Cu electronic packaging composite basic can satisfy the requirements for electronic packaging materials.

Thermodynamic Modeling of the Processes of Interaction of Calcium, Magnesium, Aluminum and Boron with Oxygen in Metallic Melts

2019 ◽  
Vol 946 ◽  
pp. 162-168
Author(s):  
Gennady G. Mikhailov ◽  
L.A. Makrovets
Keyword(s):  
Metallic Oxide ◽  
Oxide Systems ◽  
First Order ◽  
Metallic Melt ◽  
Liquid Oxide ◽  
Oxide Phases ◽  
Calcium Magnesium ◽  
Steel Deoxidation ◽  
Wagner’S Theory ◽  
Oxide Melts

A method for calculation of the diagrams of steel deoxidation and modification by calcium, magnesium, aluminum and boron was developed. The coordinates of the liquidus surfaces of the oxide systems B2O3–Al2O3–MgO, B2O3–Al2O3–CaO, B2O3–MgO–CaO were found at 1873 K. The energy parameters were determined for the theory of subregular ionic solutions of the studied oxide systems. The coordinates of the solubility surfaces for the systems Fe–Mg–Al–B–O, Fe–Ca–Al–B–O, Fe–Mg–Ca–Al–B–O were calculated. The effect of the total pressure on solubility of magnesium and calcium in liquid iron was studied. The activity of the components of the metallic melt was calculated using the first-order interaction parameters (Wagner's theory). The activities of the components of solid solutions (oxides and spinels) were equated with their molar fractions. It was shown that during extensive refining of metal from the oxygen, only a small fraction of boron oxidizes and these oxides form fraction of the oxide melts. The major non-metallic oxide inclusions were magnesia spinel, calcium bialuminate and liquid oxide formations. The "free" boron was dissolved in liquid metal in amounts which were in equilibrium with oxide phases.

Modeling and Characterization to Minimize Effects of Melt Flow Fronts on Premolded Component Deformation During In-Mold Assembly of Mesoscale Revolute Joints

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
A. Ananthanarayanan ◽  
S. K. Gupta ◽  
H. A. Bruck
Keyword(s):  
Plastic Deformation ◽  
High Speed ◽  
Polymer Melt ◽  
Production Costs ◽  
Melt Flow ◽  
Flow Front ◽  
Melting Temperatures ◽  
Second Stage ◽  
Revolute Joints ◽  
Front Position

In-mold assembly can be used to create mesoscale articulating polymeric joints that enable the miniaturization of devices, reduction in production costs, and increase in throughput. One of the major challenges in miniaturizing devices using the in-mold assembly is to develop appropriate characterization techniques and modeling approaches for the interaction between polymer melt flow fronts and premolded components. When a high speed, high temperature second stage melt comes in contact with a premolded mesoscale component that has similar melting temperatures, the premolded component can experience a significant plastic deformation due to the thermal softening and the force associated with impingement of the melt flow front. In our previous work, we developed methods to inhibit the plastic deformation by supporting the ends of the mesoscale premolded components. In this paper, we present an alternative strategy for controlling premolded component deformations. This involves a mesoscale in-mold assembly strategy that has a multigate mold design for bidirectional filling. This strategy permits in-mold assembly using polymers with comparable melting points. This paper demonstrates the technical feasibility of manufacturing in-mold-assembled mesoscale revolute joints using this bidirectional filling strategy. An experimental technique was developed for characterizing the transient impact force of the melt flow front on premolded components inside of a mold. The experimental data were used to validate a new computational model for predicting the effects of the melt flow front position in order to minimize the plastic deformation of premolded component using the bidirectional filling strategy. This paper also investigates the effects of the flow front position on the force applied on the premolded component and its corresponding plastic deformation.

High-speed UV imaging of elves and lightning from space: first simultaneous detections from the Mini-EUSO and ASIM instruments

2020 ◽  
Author(s):  
Matteo Battisti ◽  
Enrico Arnone ◽  
Mario Bertaina ◽  
Marco Casolino ◽  
Olivier Chanrion ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
High Speed ◽  
Multispectral Imaging ◽  
Gamma Ray ◽  
Single Photon ◽  
Uv Light ◽  
Photon Counting ◽  
Space Station ◽  
Wide Field ◽  
First Time

<p>The search for the physical mechanisms of lightning, transient luminous events and terrestrial gamma-ray flashes is receiving an extraordinary support by new space observations that have recently become available. Next to lightning detectors on geostationary satellites, new low orbit experiments are giving an unprecedented insight in the very source of these processes. Looking at the physics behind these new observations requires however to have a variety of different instruments covering the same event, and this is proving extremely challenging. Here, we present observations of UV emissions of elves and lightning taken for the first time simultaneously from the two instruments Mini-EUSO and ASIM operating on the international space station. Mini-EUSO was designed to perform observations of the UV-light night emission from Earth. It is a wide field of view telescope (44°x44° square FOV) installed for the first time on October 2019 inside the Zvezda Module of the ISS, looking nadir through a UV transparent window. Its optical system consists of two Fresnel lenses for light collection. The light is focused onto an array of 36 multi-anode photomultiplier tubes (MAPMT), for a total of 2304 pixels. Each pixel has a footprint on ground of ~5.5 km. The instrument is capable of single-photon counting on three different timescales: a 2.5 microsecond (D1) and a 320 microsecond (D2) timescale with a dedicated trigger system, and a 40.96ms timescale (D3) used to produce a continuous monitoring of the UV emission from the Earth. ASIM is an experiment dedicated to lightning and atmospheric processes. Its Modular Multispectral Imaging Array (MMIA) is made of an array of 3 high speed photometers probing different wavelength sampling at rates up to 100 kHz, and 2 Electron Multiplication Charge Coupled Devices (EM-CCDs) with a sub-km spatial resolution with an 80° FOV and recording up to 12 frames per second. Mini-EUSO detected several bright atmospheric events like lightning and elves, with a few km spatial resolution and different time resolutions, probing therefore different stages of the electromagnetic phenomena. Observations from Mini-EUSO were simultaneously captured by ASIM instruments, allowing for the first time to compare and complement the capabilities of the two instruments with a time inter-calibration based on unambiguous series of lightning detections.</p>

Bimaterial Micro-Structured Annulus With Zero Thermal Expansion Coefficient

2017 ◽  
Author(s):  
Yan Xie ◽  
Dengfeng Lu ◽  
Jingjun Yu
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
High Speed ◽  
Thermal Strain ◽  
Geometric Constraints ◽  
Geometrical Parameters ◽  
Thermal Behaviors ◽  
Lattice Cell ◽  
Triangular Cell

This paper mainly concentrates on the design and analysis of the annulus with zero thermal expansion coefficient (ZTE) aiming to solve the heat generation and deformation in high speed bearing. First, a fork-like lattice cell inspired by the basic triangular cell is put forward and further applied to construct an annulus. The stretch-dominated lattice cell utilizes the Poisson’s contraction effect to achieve the tailorable thermal expansion coefficient (CTE). The thermal behaviors differences between the continuous interfaces and lattice cells will lead to the internal stress. Thus, the CTE of the annulus consisting of the lattice cell can be tailored to zero even negative values through the offset between the thermal-strain and force-strain. Then a theoretical model is established with some appropriate assumptions to reveal the quantitative relations among the geometrical parameters, material properties and equivalent CTEs thoroughly. The prerequisites for realizing a zero CTE are further derived in terms of material limitations and geometric constraints. Finally, FEA method is implemented to verify and analyze the thermal behaviors of annulus. The proposed annulus design characterized by the CTE tunability, structure efficiency and continuous interfaces is hopefully to be applied in the high speed bearings, adapters between the shaft and collar and fastener screws.

scholarly journals A Model for the Anomalous Velocity-Undercooling Behaviour of Levitated Al-Ni Alloys On-board the International Space Station

2021 ◽  
Vol 33 (6) ◽  
Author(s):  
Andrew M. Mullis
Keyword(s):  
International Space Station ◽  
High Speed ◽  
Space Station ◽  
Video Data ◽  
Nucleation Temperature ◽  
International Space ◽  
Ni Alloys ◽  
Electromagnetically Levitated ◽  
Anomalous Growth ◽  
Anomalous Velocity

AbstractAl-Ni alloys (for Ni < 45 at.%) show a unique property in that, over at least part of the accessible undercooling range, the recalescence velocity measured in electromagnetically levitated samples is observed to decrease as the undercooling increases. This result has been subject to careful validation, including microgravity experiments utilising the TEMPUS levitation facility on-board the International Space Station (ISS). In these experiments, anomalous growth is observed to coincide with a recalescence morphology comprising multiple circular growth fronts [Herlach et al. Phys. Rev. Mat. 3, 073,402 (2019)], termed “scales”. In this paper we present an analysis of high speed video data from the ISS experiments in which we show that such scale-like growth is consistent with a recalescence front that is initially confined to a thin layer on the surface of the sample. This then nucleates a slower, radial inward growth, which is consistent with microstructures observed in Al-Ni droplets. We show that such surface recalescence would be favoured for samples which were surface enriched in Ni, wherein the recalescence velocity (at fixed nucleation temperature) increases rapidly with Ni-concentration. Moreover, it is shown that the anomalous velocity behaviour can be matched in all compositions studied if the surface enhancement in Ni is a linear function of the nucleation temperature with a gradient of 0.03 at.% K−1. Analysis of historical results from the literature indicates that such surface Ni-enhancement may have been present, but overlooked, in other experiments on Al-rich Al-Ni droplets.

Anisotropic Relaxation of Internal Forces in a Wound Reel of Magnetic Tape

1967 ◽  
Vol 34 (4) ◽  
pp. 888-894 ◽  
Author(s):  
H. Tramposch
Keyword(s):  
Surface Roughness ◽  
Thermal Expansion ◽  
Stress Distribution ◽  
Magnetic Tape ◽  
Digital Computer ◽  
High Speed ◽  
Coefficient Of Thermal Expansion ◽  
Internal Stresses ◽  
Numerical Examples ◽  
Internal Forces

Equations were developed to describe the relaxation of the internal stresses of a wound reel of magnetic tape, with allowances for the effects of surface roughness between tape layers and unequal thermal expansion of hub and tape-layer body. Numerical examples obtained with the aid of a high-speed digital computer indicated that the surface roughness as well as the unequal thermal expansion of hub and tape-layer body greatly affect the internal stress distribution. Essentially independent of the surface roughness, a typical reel, when stored at 120 F after being wound at 70 F and when the coefficient of thermal expansion of the hub is three times the value of the tape material, will approach stress-free conditions about 80 percent earlier than when it is stored at the winding temperature.

Thermal Analysis of a Ball-Screw System

2012 ◽  
Vol 591-593 ◽  
pp. 818-826 ◽  
Author(s):  
Chin Chung Wei ◽  
Jeng Haur Horng ◽  
Jen Fin Lin
Keyword(s):  
Finite Element ◽  
Thermal Expansion ◽  
Finite Element Model ◽  
High Speed ◽  
Element Model ◽  
Surface Strain ◽  
Ball Screw ◽  
Control Factor ◽  
Positioning Error ◽  
Positioning Control

High speed ball-screw system has serious friction heat to form thermal expansion to each component. An analyzing model considering with contact deformation and thermal expansion is established in realizing positioning error for a high speed ball-screw system. A finite element model of nut is also built in calculating elongation of nut. Surface strain of nut is measured by strain gages in order to confirm with data obtained from finite element model. Temperature of nut and screw were also measured by thermal couples and are used in calculation of elongation by the use of linear elongation equation. The tendency of positioning error is well estimated by the analyzing model. The model can be used in feedback positioning control factor and develop precision high speed ball-screw system.

Sign in / Sign up

Export Citation Format

Share Document