scholarly journals Dry Coupling of Ultrasonic Transducer Components for High Temperature Applications

Sensors ◽  
2019 ◽  
Vol 19 (24) ◽  
pp. 5383 ◽  
Author(s):  
Neelesh Bhadwal ◽  
Mina Torabi Milani ◽  
Thomas Coyle ◽  
Anthony Sinclair
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
High Efficiency ◽  
Signal To Noise Ratio ◽  
Ultrasonic Transducer ◽  
Thin Foil ◽  
Filler Material ◽  
Dry Coupling ◽  
Soft Filler ◽  
Component Interface

The viability for dry coupling of piezoelectric ultrasonic transducer components was investigated, using a thin foil of annealed silver as a filler material/coupling agent at each component interface. Criteria used for room temperature evaluation were centered on signal-to-noise ratio (SNR) and echo bandwidth, for a Li-Nb based transducer operating in pulse-echo mode. A normal clamping stress of only 25 MPa, applied repeatedly over three loading cycles on a precisely-aligned transducer stack, was sufficient to yield backwall echoes with a SNR greater than 25 dB, and a 3 dB bandwidth of approximately 65%. This compares to a SNR of 32 dB and a 3 dB bandwidth of 65%, achievable when all transducer interfaces were coupled with ultrasonic gel. The respective roles of a soft filler material, alignment of transducer components, cyclic clamping, component roughness, and component flatness were evaluated in achieving this high efficiency dry coupling, with transducer clamping forces far lower than previously reported. Preliminary high temperature tests indicate that this coupling method is suitable for high temperature and achieves signal quality comparable to that at room temperature with ultrasonic gel.

scholarly journals Mn-doped CaBi4Ti4O15/Pb(Zr,Ti)O3 Ultrasonic Transducers for Continuous Monitoring at Elevated Temperatures

2017 ◽  
Author(s):  
Makiko Kobayashi ◽  
Taiga Kibe ◽  
Hajime Nagata
Keyword(s):  
High Temperature ◽  
Thermal Cycle ◽  
Elevated Temperatures ◽  
Signal To Noise Ratio ◽  
Ultrasonic Transducer ◽  
Sol Gel ◽  
Ultrasonic Transducers ◽  
In Situ Monitoring ◽  
Signal To Noise ◽  
Noise Ratio

Continuous ultrasonic in-situ monitoring for industrial applications is difficult owing to the high operating temperatures in industrial fields. It is expected that ultrasonic transducers consisting of CaBi4Ti4O15(CBT)/Pb(Zr,Ti)O3(PZT) sol-gel composite could be one solution for ultrasonic nondestructive testing (NDT) above 500 C because no couplant is required and CBT has a high Curie temperature. To verify the high temperature durability, CBT/PZT sol-gel composite films were fabricated on titanium substrates by spray coating, and the CBT/PZT samples were tested in a furnace at various temperatures. Reflected echoes with a high signal-to-noise ratio were observed up to 600 C. A thermal cycle test was conducted from room temperature to 600 C, and no significant deterioration was found after the second thermal cycle. To investigate the long-term high-temperature durability, a CBT/PZT ultrasonic transducer was tested in the furnace at 600 °C for 36 h. Ultrasonic responses were recorded every 3 h, and the sensitivity and signal-to-noise ratio were stable throughout the experiment.

Toward An Ultrasonic Sensor for Pressure Vessels

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
J. S. Sandman ◽  
B. R. Tittmann
Keyword(s):  
High Temperature ◽  
Target Location ◽  
Signal To Noise Ratio ◽  
Ultrasonic Transducer ◽  
Piezoelectric Element ◽  
Ambient Air ◽  
Pressure Vessels ◽  
Finite Element Program ◽  
Housing Design ◽  
Wave Forms

The focus of this paper is an ultrasonic position indication system that is capable of determining one-dimensional target location in a high-temperature steel container with gaseous medium. The combination of the very high acoustical impedance of steel (45.4MRayl) and the very low impedance of a gas, for example, ambient air (0.0004MRayl), causes significant reflections at the interfaces. The strategy of this investigation was to develop an ultrasonic transducer capable of replacing a small portion of pressure vessel wall. In building such a transducer, acoustic matching layers for the steel-gas interface, a mechanically and acoustically competent housing, an efficient piezoelectric element, and appropriate backing materials are developed and tested. The results include a successful housing design, high- temperature acoustic matching layers, and subsequent successful wave forms with good signal-to-noise ratio. Target location through 9.6in.(24.5cm) of ambient air was possible, with a steel pressure boundary 0.456in.(1.160cm) thick, and the use of one matching layer. Our transducer was tested repeatedly to 340°C without apparent degradation. In addition to the experimental results, this investigation includes numerical simulations. Sample wave forms were predicted one dimensionally with the coupled acoustic piezoelectric analysis, a finite element program that predicts wave forms based on Navier’s equation for elastic wave propagation.

Hydrogen generation from formic acid decomposition on a highly efficient iridium catalyst bearing a diaminoglyoxime ligand

2018 ◽  
Vol 20 (8) ◽  
pp. 1835-1840 ◽  
Author(s):  
Sheng-Mei Lu ◽  
Zhijun Wang ◽  
Jijie Wang ◽  
Jun Li ◽  
Can Li
Keyword(s):  
High Temperature ◽  
Formic Acid ◽  
Room Temperature ◽  
High Efficiency ◽  
Hydrogen Generation ◽  
Acid Decomposition ◽  
Highly Efficient ◽  
Iridium Catalyst ◽  
Formic Acid Decomposition ◽  
Aqueous Formic Acid

A new iridium catalyst bearing a dioxime derived ligand has been developed for aqueous formic acid (FA) dehydrogenation in the absence of any additives. These catalysts can work at high temperature or room temperature with high efficiency and stability.

FTIR Characterization of the Residues of High-Temperature Extraction and Subsequent Oxidization Depolymerization of Lignite

2011 ◽  
Vol 236-238 ◽  
pp. 645-648
Author(s):  
Zhi Cai Wang ◽  
Juan Gao ◽  
Heng Fu Shui ◽  
Chun Xiu Pan ◽  
Fa Guo Chong ◽  
...  
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
High Efficiency ◽  
Mixed Solvent ◽  
Covalent Bond ◽  
Methylene Bridge ◽  
Ftir Characterization ◽  
Thermal Extraction ◽  
Efficiency Conversion

In order to explore high-efficiency utilization approach of lignite, Xianfeng lignite was extracted by toluene/methanol (3:1) mixed solvent under 300°C in an autoclave combined with high-temperature separator. Subsequently, the thermal extraction residue was oxidized by 3% hydrogen peroxide aqueous solution at room temperature. The raw coal and its residues of thermal extraction and oxidization were further extracted respectively by THF and CS2/NMP mixed solvent, and the extracts and the extraction residues were characterized by FTIR. The results indicate that thermal extraction of lignite relaxes the network structure of coal matrix by disrupture the non-covalent bond interactions. The methylene bridge bond is easy to be oxidized into carboxyl and hydroxyl functional groups. Therefore, these results are very significant for the development of high-efficiency conversion technology.

The Development of Alumina Forming Austenitic Alloy for Core Application in Advanced Nuclear Reactors

2020 ◽  
Vol 999 ◽  
pp. 72-80
Author(s):  
Zhang Jian Zhou ◽  
Ling Zhi Chen ◽  
Yuan Gao ◽  
Qi Wang
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Room Temperature ◽  
High Efficiency ◽  
Nuclear Reactors ◽  
Potential Applications ◽  
Core Components ◽  
High Burnup ◽  
Corrosive Environments

The development of materials for core components which can serve in high temperature corrosive environments for a long service time is crucial to realize high efficiency and high-burnup operation of advanced nuclear reactors. Alumina forming austenitic (AFA) alloy is a kind of promising materials with improved corrosion resistance as well as strength at elevated temperature. The progress on the composition design and characterization of AFA alloys are reviewed in this work for evaluation their potential applications in advanced nuclear reactors. AFA alloys without the addition of carbon have been fabricated. Microstructures were observed by SEM and TEM. Mechanical properties were measured at room temperature and high temperature.

Flow Signal Characteristics of an Ultrasonic Transducer at a High Temperature

2011 ◽  
Author(s):  
Ki Won Lim ◽  
Jaeheun Rho
Keyword(s):  
High Temperature ◽  
Power Plant ◽  
Nuclear Power Plant ◽  
Transit Time ◽  
Nuclear Power ◽  
Room Temperature ◽  
Ultrasonic Transducer ◽  
Feed Water ◽  
Pipe Line ◽  
Driving Circuit

The exact measurement of feed water flow is the major factor in nuclear power plant efficiency. However, due to the fouling problem, the venturi nozzle used in feed water measurement frequently causes a decrease in the efficiency of the nuclear power plant. To avoid this problem, ultrasonic technology is a reasonable candidate. The temperature of the feed water is about 300 °C. The commercial piezoelectric element used in an ultrasonic transducer preserves its characteristics up to a temperature of 120 °C. This problem must be overcome in order to use an ultrasonic flowmeter to measure the feed water flow. To address this issue, we designed a thermal block to insulate the high temperature from the pipe line. The method we used included a clamp-on type transducer and a driving circuit with a transit time difference method. The signals from the driving circuit were measured and the ultrasonic transducer assembly was tested at room temperature and at a high temperature of 300 °C. The test results revealed that the transit time difference was reasonably proportional to the flow velocity at room temperature, and the signals of the transducer installed on the pipe line were the same at 300 °C as those at room temperature. This result confirmed that the ultrasonic pulse was working well through the thermal block and in the high temperature fluid.

Dislocation structures around SiO2 Particles in aged Cu-Cr-SiO2

1978 ◽  
Vol 36 (1) ◽  
pp. 594-595
Author(s):  
N.J. Long ◽  
M.H. Loretto ◽  
C.H. Lloyd
Keyword(s):  
Flow Stress ◽  
Single Crystals ◽  
Room Temperature ◽  
Thin Foil ◽  
Age Hardening ◽  
Dispersion Strengthening ◽  
Accurate Picture ◽  
The Matrix ◽  
Very High ◽  
Good Agreement

IntroductionThere have been several t.e.m. studies (1,2,3,4) of the dislocation arrangements in the matrix and around the particles in dispersion strengthened single crystals deformed in single slip. Good agreement has been obtained in general between the observed structures and the various theories for the flow stress and work hardening of this class of alloy. There has been though some difficulty in obtaining an accurate picture of these arrangements in the case when the obstacles are large (of the order of several 1000's Å). This is due to both the physical loss of dislocations from the thin foil in its preparation and to rearrangement of the structure on unloading and standing at room temperature under the influence of the very high localised stresses in the vicinity of the particles (2,3).This contribution presents part of a study of the Cu-Cr-SiO2 system where age hardening from the Cu-Cr and dispersion strengthening from Cu-Sio2 is combined.

AFM study of the dynamics of α-alumina surface faceting during high-temperature processing

1995 ◽  
Vol 53 ◽  
pp. 334-335 ◽  
Author(s):  
Michael W. Bench ◽  
Jason R. Heffelfinger ◽  
C. Barry Carter
Keyword(s):  
High Temperature ◽  
Thin Foil ◽  
Sem Analysis ◽  
Conductive Coatings ◽  
Force Microscopy ◽  
Minimal Sample ◽  
Atomic Force ◽  
Formation And Evolution ◽  
High Temperature Processing ◽  
Nominal Surface

To gain a better understanding of the surface faceting that occurs in α-alumina during high temperature processing, atomic force microscopy (AFM) studies have been performed to follow the formation and evolution of the facets. AFM was chosen because it allows for analysis of topographical details down to the atomic level with minimal sample preparation. This is in contrast to SEM analysis, which typically requires the application of conductive coatings that can alter the surface between subsequent heat treatments. Similar experiments have been performed in the TEM; however, due to thin foil and hole edge effects the results may not be representative of the behavior of bulk surfaces.The AFM studies were performed on a Digital Instruments Nanoscope III using microfabricated Si3N4 cantilevers. All images were recorded in air with a nominal applied force of 10-15 nN. The alumina samples were prepared from pre-polished single crystals with (0001), , and nominal surface orientations.

Observations on the structure at the transformation interface of pearlite in steel

1990 ◽  
Vol 48 (4) ◽  
pp. 200-201
Author(s):  
F. A. Khalid ◽  
D. V. Edmonds
Keyword(s):  
Room Temperature ◽  
Thin Foil ◽  
Carbon Steels ◽  
Model Alloy ◽  
Growth Interface ◽  
Medium Carbon ◽  
Solution Treated ◽  
Medium Carbon Steels ◽  
Alloy Carbide ◽  
Hot Rolled

The austenite/pearlite growth interface in a model alloy steel (Fe-1 lMn-0.8C nominal wt%) is being investigated. In this particular alloy pearlite nodules can be grown isothermally in austenite that remains stable at room temperature, thus facilitating examination of the transformation interfaces. This study presents preliminary results of thin foil TEM of the austenite/pearlite interface, as part of a programme of aimed at studying alloy carbide precipitation reactions at this interface which can result in significant strengthening of microalloyed low- and medium- carbon steels L Similar studies of interface structure, made on a partially decomposed high- Mn austenitic alloy, have been reported recently.The experimental alloys were made as 50 g argon arc melts using high purity materials and homogenised. Samples were hot- rolled, swaged and machined to 3mm diameter rod, solution treated at 1300 °C for 1 hr and WQ. Specimens were then solutionised between 1250 °C and 1000 °C and isothermally transformed between 610 °C and 550 °C for 10-18 hr and WQ.

ABOUT HEAT CAPACITY OF TITANIUM CARBIDE TiCx

2019 ◽  
pp. 56-66
Author(s):  
I. Khidirov ◽  
V. V. Getmanskiy ◽  
A. S. Parpiev ◽  
Sh. A. Makhmudov
Keyword(s):  
Heat Capacity ◽  
High Temperature ◽  
Titanium Carbide ◽  
Temperature Dependence ◽  
Carbon Concentration ◽  
Room Temperature ◽  
Thermodynamic Characteristics ◽  
Liquid Nitrogen Temperature ◽  
Analysis Data ◽  
Thermal Excitation

This work relates to the field of thermophysical parameters of refractory interstitial alloys. The isochoric heat capacity of cubic titanium carbide TiCx has been calculated within the Debye approximation in the carbon concentration  range x = 0.70–0.97 at room temperature (300 K) and at liquid nitrogen temperature (80 K) through the Debye temperature established on the basis of neutron diffraction analysis data. It has been found out that at room temperature with decrease of carbon concentration the heat capacity significantly increases from 29.40 J/mol·K to 34.20 J/mol·K, and at T = 80 K – from 3.08 J/mol·K to 8.20 J/mol·K. The work analyzes the literature data and gives the results of the evaluation of the high-temperature dependence of the heat capacity СV of the cubic titanium carbide TiC0.97 based on the data of neutron structural analysis. It has been proposed to amend in the Neumann–Kopp formula to describe the high-temperature dependence of the titanium carbide heat capacity. After the amendment, the Neumann–Kopp formula describes the results of well-known experiments on the high-temperature dependence of the heat capacity of the titanium carbide TiCx. The proposed formula takes into account the degree of thermal excitation (a quantized number) that increases in steps with increasing temperature.The results allow us to predict the thermodynamic characteristics of titanium carbide in the temperature range of 300–3000 K and can be useful for materials scientists.

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