Effect of Annealing on High Frequency Viscoelastic Waves in Spincoated Polymer thin Films

1994 ◽  
Vol 356 ◽  
Author(s):  
J. R. Dutcher ◽  
Z. Wang ◽  
B. J. Neal ◽  
T. Copeland ◽  
J. R. Stevens
Keyword(s):  
Thin Films ◽  
High Frequency ◽  
Room Temperature ◽  
Guided Waves ◽  
Elevated Temperatures ◽  
Film Surface ◽  
Guided Wave ◽  
Heating Effects ◽  
Viscoelastic Waves ◽  
The Waves

AbstractWe present a study of the effect of elevated temperatures on the high frequency viscoelastic waves guided by thin films of poly(styrene) [PS] and poly(methyl methacrylate) [PMMA]. The films, which are spincoated onto Si(OOl) wafers, have thicknesses h ˜ 1000 Å. The frequencies and linewidths of the film-guided waves were measured using Brillouin light scattering (BLS). In both PS and PMMA, we observed guided waves for temperatures above the glass transition temperature Tg of the polymers, however, the damping of the waves for temperatures above Tg was significantly higher for PS. We observed no significant (< 1 %) difference between room temperature guided-wave frequencies for films annealed at temperatures below and above Tg for PS, and a slight (4 %) increase in the wave frequency for PMMA following annealing at a temperature above Tg. The heating effects due to the focussing of the laser beam on the film surface are quite small (˜ 16°C/100 mW laser power).

Influence of Momentary Annealing on the Nanoscale Surface Morphology of Room Temperature Pulsed Laser Deposited NiO(111) Epitaxial Thin Films on Atomically Stepped Sapphire (0001) Substrates

2013 ◽  
Vol 1507 ◽  
Author(s):  
Ryosuke Yamauchi ◽  
Geng Tan ◽  
Daishi Shiojiri ◽  
Nobuo Tsuchimine ◽  
Koji Koyama ◽  
...  
Keyword(s):  
Thin Films ◽  
Surface Morphology ◽  
Room Temperature ◽  
Pulsed Laser ◽  
Film Surface ◽  
Transient State ◽  
Epitaxial Thin Films ◽  
Flat Surfaces ◽  
Surface Nanostructure ◽  
Atomically Flat

ABSTRACTWe examined the influence of momentary annealing on the nanoscale surface morphology of NiO(111) epitaxial thin films deposited on atomically stepped sapphire (0001) substrates at room temperature in O2 at 1.3 × 10−3 and 1.3 × 10−6 Pa using a pulsed laser deposition (PLD) technique. The NiO films have atomically flat surfaces (RMS roughness: approximately 0.1–0.2 nm) reflecting the step-and-terrace structures of the substrates, regardless of the O2 deposition pressure. After rapid thermal annealing (RTA) of the NiO(111) epitaxial film deposited at 1.3 × 10−3 Pa O2, a periodic straight nanogroove array related to the atomic steps of the substrate was formed on the film surface for 60 s. In contrast, the fabrication of a transient state in the nanogroove array formation was achieved with RTA of less than 1 s. However, when the O2 atmosphere during PLD was 1.3 × 10−6 Pa, random crystal growth was observed and resulted in a disordered rough surface nanostructure after RTA.

scholarly journals Development of Ultrasonic Guided Wave Transducer for Monitoring of High Temperature Pipelines

Sensors ◽  
2019 ◽  
Vol 19 (24) ◽  
pp. 5443 ◽  
Author(s):  
Anurag Dhutti ◽  
Saiful Asmin Tumin ◽  
Wamadeva Balachandran ◽  
Jamil Kanfoud ◽  
Tat-Hean Gan
Keyword(s):  
High Temperature ◽  
Guided Waves ◽  
Elevated Temperatures ◽  
Element Model ◽  
Wave Mode ◽  
Guided Wave ◽  
Electromechanical Impedance ◽  
Active Sensor ◽  
Ultrasonic Guided Wave ◽  
Modes Of Vibration

High-temperature (HT) ultrasonic transducers are of increasing interest for structural health monitoring (SHM) of structures operating in harsh environments. This article focuses on the development of an HT piezoelectric wafer active sensor (HT-PWAS) for SHM of HT pipelines using ultrasonic guided waves. The PWAS was fabricated using Y-cut gallium phosphate (GaPO4) to produce a torsional guided wave mode on pipes operating at temperatures up to 600 °C. A number of confidence-building tests on the PWAS were carried out. HT electromechanical impedance (EMI) spectroscopy was performed to characterise piezoelectric properties at elevated temperatures and over long periods of time (>1000 h). Laser Doppler vibrometry (LDV) was used to verify the modes of vibration. A finite element model of GaPO4 PWAS was developed to model the electromechanical behaviour of the PWAS and the effect of increasing temperatures, and it was validated using EMI and LDV experimental data. This study demonstrates the application of GaPO4 for guided-wave SHM of pipelines and presents a model that can be used to evaluate different transducer designs for HT applications.

A1Bi3C6 Thin Films as NO Sensors

2006 ◽  
Vol 915 ◽  
Author(s):  
Halyna Khlyap ◽  
Violetta Bilozertseva ◽  
Nina Dyakonenko ◽  
Dmitrii Gaman ◽  
Andrey Mamalui ◽  
...  
Keyword(s):  
Thin Films ◽  
Room Temperature ◽  
Film Surface ◽  
Electrophysical Properties ◽  
Growth Morphology ◽  
Vacuum Level ◽  
Glass Substrates ◽  
Aggressive Environment ◽  
Vacuum Technology ◽  
Before And After

AbstractThe paper reports experimental data on growth, morphology, NO sensitivity and electrophysical properties of A1Bi3C6 thin films obtained by means of simple vacuum technology. The investigated samples were condensed onto the glass substrates under deposition rate 0.1-0.5 nm/s at T = 300 K and vacuum level P = 10-3 Pa. AFM investigations of the film surface before and after interaction with aggressive environment demonstrated sufficient sensitivity of the film relief to the aggressive component. Room-temperature electric field-induced characteristics were investigated for metal-semiconductor (MS) Cr/NaBiTe2 structures.

Modeling guided waves to constrain the velocity structure of the oceanic crust in the subduction zone of eastern Alaska

2020 ◽  
Author(s):  
Xiaoyu Guan ◽  
Yuanze Zhou ◽  
Takashi Furumura
Keyword(s):  
Subduction Zone ◽  
Oceanic Crust ◽  
High Frequency ◽  
Subduction Zones ◽  
Guided Waves ◽  
Velocity Structure ◽  
Guided Wave ◽  
S Wave ◽  
Arrival Times ◽  
Velocity Models

&lt;p&gt;Fitting subduction zone guided waves with synthetics is an ideal choice for studying the velocity structure of the oceanic crust. After an earthquake occurs in subduction zones, seismic waves can be trapped in the low-velocity oceanic crust and propagated as guided waves. The arrival time and frequency characteristics of the guided waves can be used to image the velocity structure of the oceanic crust. The analysis and modeling based on guided wave observations provide a rare opportunity to understand the velocity structure of the oceanic crust and the variations in oceanic crustal materials during the subduction process.&lt;/p&gt;&lt;p&gt;High-frequency guided waves have been observed in the subduction zone of eastern Alaska. On several sections, observed seismograms recorded by seismic stations show low-frequency (&lt;2Hz) onsets ahead of the main high-frequency (&gt;2Hz) guided waves. Differences in the arrival times and dispersion characteristics of seismic phases are related to the velocity structure of the oceanic crust, and the characteristics of coda waves are related to the distribution of elongated scatters in the oceanic crust. Through fitting the observed broadband waveforms and synthetics modeled with the 2-D FDM (Finite Difference Method), we obtain the preferred oceanic crustal velocity models for several sections in the subduction zone of eastern Alaska. The preferred models can explain the seismic phase arrival times, dispersions, and coda characteristics in the observed waveforms. With the obtained P- and S- wave models of velocity structures on several sections, the material compositions they represent are deduced, and the variations of oceanic crustal materials during subducting can be understood. This provides new evidence for studying the details of the subduction process in the subduction zone of eastern Alaska.&lt;/p&gt;

scholarly journals Piezoresponse force microscopy and dielectric spectroscopy study of Ba0.6Sr0.4TiO3 thin films

2019 ◽  
Vol 09 (03) ◽  
pp. 1950025
Author(s):  
Dionizy Czekaj ◽  
Agata Lisińska-Czekaj
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Room Temperature ◽  
Sol Gel ◽  
Film Surface ◽  
Piezoresponse Force Microscopy ◽  
Elementary Cell ◽  
Structure Property ◽  
Average Roughness ◽  
Force Microscopy

Research on synthesis, characterization and determination of processing — structure — property relationships of commercially important ferroelectric thin films has been performed. The sol–gel type solution deposition technique was applied to produce good quality thin films of [Formula: see text][Formula: see text]TiO3 (BST60/40) chemical composition on the stainless steel substrates. The thin films were characterized in terms of their microstructure, crystal structure, phase composition, piezoelectric and dielectric properties. It was found that the BST60/40 thin film adopted the cubic structure at room temperature with an elementary cell parameter [Formula: see text] Å. Morphology of the thin film surface was studied with Atomic Force Microscopy (AFM). Average roughness of the thin films surface was found ([Formula: see text]m). Piezoresponse Force Microscopy (PFM) was applied for the thin film characterization. Active piezoelectric regions were found in BST60/40 thin film. Therefore, dielectric response measured at room temperature was studied in assumption of piezoelectric electric equivalent circuit.

Experimental Study of High Frequency Guided Wave Inspection of Anchored Bolts

2011 ◽  
Vol 117-119 ◽  
pp. 962-966 ◽  
Author(s):  
Wen He ◽  
Xiao Jiang Luo ◽  
Kui Zhao ◽  
Wang Cheng ◽  
Chun Hui Zhong
Keyword(s):  
Spectral Density ◽  
Power Spectral Density ◽  
High Frequency ◽  
Guided Waves ◽  
Broad Band ◽  
Frequency Component ◽  
Guided Wave ◽  
Reflected Waves ◽  
Power Spectral ◽  
Density Values

High frequency longitudinal guided waves were used to inspect the anchored rock bolts. Experiments were conducted to find the optimal frequencies for the bolt testing. A broad-band signal was excited at the top end of the bolt, and the power spectral density(PSD) analysis of the bolt end reflected waves was made. Base on that the frequency component of the bolt end reflected waves could be obtain, and the frequencies with higher power spectral density values are the optimal ones. At optimal frequencies, the guided wave attenuates more slightly than it is at other frequencies and the bolt end reflected waves can be clearly acquisitioned. Experimental results show that the optimal frequencies of guided wave in a free bolt and in an anchored bolt are quite the same, and they are mainly affected by the bolt instead of the anchor media. Conclusions can be drawn that the propagation velocities of guided wave at optimal frequencies in a free bolt are close to those in the embedded section of the bolt. As a result, the bolt length and the position of flaw in the anchored bolt can be determined by the guided wave velocity in a free bolt and the reflected wave from the bolt end and from the flaw, respectively.

scholarly journals Core–skin debonding detection in honeycomb sandwich structures through guided wave wavefield analysis

2018 ◽  
Vol 30 (9) ◽  
pp. 1306-1317 ◽  
Author(s):  
Lingyu Yu ◽  
Zhenhua Tian ◽  
Xiaopeng Li ◽  
Rui Zhu ◽  
Guoliang Huang
Keyword(s):  
Guided Waves ◽  
Sandwich Structures ◽  
Lamb Waves ◽  
Laser Doppler Vibrometer ◽  
Low Frequency ◽  
Guided Wave ◽  
Honeycomb Sandwich ◽  
Debonding Detection ◽  
The Waves ◽  
Detection And Quantification

Ultrasonic guided waves have proven to be an effective and efficient method for damage detection and quantification in various plate-like structures. In honeycomb sandwich structures, wave propagation and interaction with typical defects such as hidden debonding damage are complicated; hence, the detection of defects using guided waves remains a challenging problem. The work presented in this article investigates the interaction of low-frequency guided waves with core–skin debonding damage in aluminum core honeycomb sandwich structures using finite element simulations. Due to debonding damage, the waves propagating in the debonded skin panel change to fundamental antisymmetric Lamb waves with different wavenumber values. Exploiting this mechanism, experimental inspection using a non-contact laser Doppler vibrometer was performed to acquire wavefield data from pristine and debonded structures. The data were then processed and analyzed with two wavefield data–based imaging approaches, the filter reconstruction imaging and the spatial wavenumber imaging. Both approaches can clearly indicate the presence, location, and size of the debonding in the structures, thus proving to be effective methods for debonding detection and quantification for honeycomb sandwich structures.

Substantiation of a Technique of Determining Stress in Thin Films at Very Low Temperatures

2015 ◽  
Vol 14 ◽  
pp. 28-36
Author(s):  
C.C. Chama
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Low Temperatures ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
High Temperature Stress ◽  
Hysteresis Curves ◽  
Stress Hysteresis

Substantiation of a technique earlier employed in determining stress in Copper-Silver thin films at very low temperatures is presented. It is shown that the stress measured at elevated temperatures using Stoney’s equation can be utilized in the determination of stress at very low temperatures. To demonstrate the application of this technique, a case study has been conducted by utilizing stress hysteresis curves obtained from the Cu-6at%Ag thin film heated from room temperature to 400°C and cooled back to room temperature in two cycles. The stresses in the Cu-6at%Ag thin film at various low temperatures up to-197°C have been determined by utilizing data from high temperature stress hysteresis curves.

scholarly journals Improving accuracy through density correction in guided wave tomography

2016 ◽  
Vol 472 (2186) ◽  
pp. 20150832 ◽  
Author(s):  
P. Huthwaite
Keyword(s):  
Guided Waves ◽  
Low Frequency ◽  
Region Of Interest ◽  
Density Variation ◽  
Pressure Vessels ◽  
Guided Wave ◽  
Wave Tomography ◽  
Wall Loss ◽  
Improving Accuracy ◽  
The Waves

The accurate quantification of wall loss caused by corrosion is critical to the reliable life estimation of pipes and pressure vessels. Traditional thickness gauging by scanning a probe is slow and requires access to all points on the surface; this is impractical in many cases as corrosion often occurs where access is restricted, such as beneath supports where water collects. Guided wave tomography presents a solution to this; by transmitting guided waves through the region of interest and exploiting their dispersive nature, it is possible to build up a map of thickness. While the best results have been seen when using the fundamental modes A0 and S0 at low frequency, the complex scattering of the waves causes errors within the reconstruction. It is demonstrated that these lead to an underestimate in wall loss for A0 but an overestimate for S0. Further analysis showed that this error was related to density variation, which was proportional to thickness. It was demonstrated how this could be corrected for in the reconstructions, in many cases resulting in the near-elimination of the error across a range of defects, and greatly improving the accuracy of life estimates from guided wave tomography.

Electrical Property of Transparent Thin Films TiO2 and Sr-Doped TiO2 Developed by Spin Coating

2013 ◽  
Vol 665 ◽  
pp. 263-266
Author(s):  
M.H. Mangrola ◽  
A.S. Pillai ◽  
B.H. Parmar ◽  
V.G. Joshi
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Electrical Property ◽  
Spin Coating ◽  
Glass Substrate ◽  
High Frequency ◽  
Ac Conductivity ◽  
Room Temperature ◽  
Coating Technique ◽  
Increase With Increase

Transparent thin film of pure TiO2and 3% Sr-doped TiO2(Ti0.97Sr0.03O2) were prepared by spin coating technique onto well-cleaned glass substrate. The dielectric behaviour of the films were studied at room temperature for different frequencies. The capacitance of both films were is found to decrease with increasing frequency and at higher frequencies capacitance becomes constant. AC conductivity is found to continuously increase with increase in the frequency. At high frequency it doesnt show any change and remains almost constant.

Sign in / Sign up

Export Citation Format

Share Document