Applicable Temperature Range Research Articles

Forming operation in Ge-rich GexSbyTez phase change memories

Optimized Ge-rich GexSbyTez materials with improved crystallization temperature have been proven to guarantee code integrity after soldering thermal profile and data retention in extended temperature range for automotive application. Together with higher crystallization temperature, these materials show also peculiar characteristics of the crystalline state with respect to conventional GST (Ge2Sb2Te5). In particular integrated memory cell shows a very high virgin resistance and needs an electrical activation as last operation of the fabrication process. In this paper we investigate for the first time the role of this electrical activation we named forming operation. In particular we show that the level of the maximum current flowing into the cell at the first electrical activation (forming level) has an impact on cell programmability. An explanation of this behavior based on physical analysis is provided suggesting that it is related to the modulation of cell thermal efficiency. Finally it is shown how forming level can be used in order to optimize cell reliability with respect to requested specifications for high temperature data retention (HTDR) and endurance.

Viscoelastic Vibration Damping Materials for Application in a Temperature Range above 150°C

We demonstrate a new type of viscoelastic vibration damping material with high damping performances (tan δ=E′/E′′ ≥0.3 where E′ and E′′ are the storage and loss Young’s moduli, respectively) at a high temperature range between 200°C and 250°C utilizing a special polymer resin of higher glass transition temperature corresponding to the application temperature range and larger pendant groups offering higher efficiency of the energy dissipation. In addition, the damping property of the bulk material reinforced with glass fiber will be significantly improved, where the peak tan δ value can reach 0.7. In this paper, we put the emphasis on the preparation process and properties characterization of this new type material, and try to provide a new method to fabricate a viscoelastic damping material (VDM) usable for applications in the field of high temperature vibration reduction, in contrast to the conventional ones whose damping properties will dramatically decay once the ambient temperature is above 100°C.

Electromagnetic flowmeter with non-insulation pipe wall

The internal pipe wall of the Electromagnetic Flowmeter (EMFM) must be non-conductive to prevent the generated electromotive force from short-circuiting. Usually the inside of metallic pipes is lined with insulating material. The lining limits the applicable temperature range of measured fluid and also its reliability. A new structure is proposed, in which the insulating liner is eliminated and replaced with non-insulation material. A potential distribution is formed on the pipe wall by applying voltage proportional to fluid flow rate. The potential distribution is decided by the conducting pipe wall. In this paper theoretical analysis and experimental results of EMFM with non-insulation pipe wall are described.

Electromagnetic flow meter with non-insulation pipe wall for liquid sodium in nuclear reactors

An electromagnetic flow meter (EMFM) with non-insulation pipe wall that may be used in the Fast Reactor Test Facility (FARET) has been designed and partially tested. The internal pipe wall of EMFMs must be non-conductive to prevent generated electromotive force from short circuiting. Usually the inside of metallic pipes is lined with insulating material. The lining limits the applicable temperature range of measured fluid and also its reliability. A new structure is proposed, in which the insulating liner is eliminated and metallic pipe instead of non-insulation material. Also a servo system is applied. Therefore, the output signal is exactly the same as that of conventional EMFMs. In this paper, an analytical method based on conducting wall boundary conditions and experimental results is described.

Electromagnetic flowmeter with non-insulation pipe wall

The internal pipe wall of the Electromagnetic Flowmeter (EMFM) must be non-conductive to prevent the generated electromotive force from short-circuiting. Usually the inside of metallic pipes is lined with insulating material. The lining limits the applicable temperature range of measured fluid and also its reliability. A new structure is proposed, in which the insulating liner is eliminated and replaced with non-insulation material. A potential distribution is formed on the pipe wall by applying voltage proportional to fluid flow rate. The potential distribution is decided by the conducting pipe wall. In this paper theoretical analysis and experimental results of EMFM with non-insulation pipe wall are described.

Acrylic-based composite latexes containing nano-sized liquid crystalline domains

Two-scale multicomposite (meth)acrylate latexes containing nano-sized liquid crystalline domains were synthesized in a two step (mini)emulsion polymerization using a series of methacrylate side chain liquid crystalline monomers and mixture of short chain (meth)acrylates. Detailed characterization of the composite films obtained from the latexes using a combination of DSC, TEM, polarized light microscopy, SAXS and WAXS showed that the liquid crystalline polymers had a layered structure with a 2D-organization that was not perturbed by the amorphous polymer, which on the other hand was partially intercalated between layers. This leads to a two-scale composite with enhanced mechanical properties and higher number of degrees of freedom to fine tune the mechanical properties. The effect of liquid crystalline domains on barrier properties as well as on the water resistance of the films formed from these latexes was also investigated. The persistence of crystalline order of the liquid crystalline polymer phase up to very high temperatures leads to materials with a very broad temperature range of application, improving significantly the performance with respect to other routes based on incorporation of crystalline domains via copolymerization with comb-like monomers.

Molecular design and synthesis of acrylic resin film-forming materials with wide applicable temperature range via RAFT emulsion polymerization

Abstract The symmetric polystyrene- block -poly( n -butyl acrylate)- block -polystyrene (SAS) triblock copolymers with wide applicable temperature range have been designed and synthesized via reversible addition-fragmentation chain transfer (RAFT) emulsion polymerization. The high poly( n -butyl acrylate) (PBA) block content introduced will endow the SAS with the ability of working as film-forming materials. The microphase separation and mechanism of wide applicable temperature range were investigated by differential scanning calorimetry and dynamic mechanical analysis (DMA). The static and dynamic mechanical properties, visible light transmittance, water resistance and thermal stability of SAS were also characterized by tensile test, DMA, spectrophotometer, water absorption and thermogravimetric analysis. The tensile strength decreases and elongation at break increases with the PBA block content of SAS increasing from 50 wt.% to 70 wt.%. The maximum elongation at break reaches 707%. The broad thermoplastic elastic region from −40 °C to 80 °C works well in the surrounding of a big temperature difference due to the PBA block in rubbery state and the PSt block in glassy state. The SAS has high transmittance, low water absorption and favorable thermal stability. This research will provide a reference for film-forming materials with wide applicable temperature range.

<i>In Situ</i> Techniques for the Investigation of the Kinetics of Austenitization of Supermartensitic Stainless Steel

The austenitization and inter-critical annealing of X4CrNiMo16-5-1 (1.4418) supermartensitic stainless steel were investigated in-situ with synchrotron X-ray diffraction (XRD), dilatometry and differential scanning calorimetry (DSC) under isochronal heating conditions. Austenitization occurred in two stages: the austenitization started at approx. 600 °C, decelerated at approx. 700 °C at 60 to 75 v.% of transformed austenite, and first resumed after heating for approx. 100 °C. This plateau in the transformation curve was more dominant for faster heating rates. Inter-critical annealing at 675 and 700 °C revealed, that austenite can to a certain extent be stabilized to room-temperature. There was good agreement for the transformation curves yielded by dilatometry and XRD. Some deviation occurred due to the different applied heating principles, different temperature monitoring and the impact of surface martensite formation on the XRD measurement. The applicable temperature range for DSC as well as the close proximity of the Ac1- and the Curie-temperature limited the usage of the technique in the present case.

Impact of temperature on conduction mechanisms and switching parameters in HfO2-based 1T-1R resistive random access memories devices

In this work, the impact of temperature in the range from −40 to +150 °C on the leakage mechanism and resistive switching voltages of 1T-1R HfO2-based devices is investigated. By using incremental step pulses with an additional read and verify algorithm, the devices are switched from the high resistive state (HRS) to the low resistive state (LRS) and vice versa. In the HRS, the leakage current values are not affected by the temperature, suggesting a tunnel-like conduction mechanism through the filament constriction. By applying the quantum-point contact model, this temperature independence is attributed to compensation between the width and the height variations of the tunnel barrier. In contrast to the HRS, the leakage currents values of the LRS are decreasing linearly with raising temperature, suggesting a metal-like conduction mechanism. Therefore, the on/off ratio is slightly decreasing with increasing temperature. Regarding the switching voltages, no impact of temperature was found, ensuring stable switching cycles of the devices in the relevant temperature range for applications.

Revision to the humidity correction equation in the calculation formulae of the air refractive index based on a phase step interferometer with three frequency-stabilized lasers

At present the formulae proposed by G Boensch and E Potulski in 1998 (Boensch and Potulski 1998 Metrologia 35 133–9) are mostly used to calculate the air refractive index. However, the humidity correction equation in the formulae is derived by using the light source of a Cd lamp whose light frequency stability is poor and at a narrow temperature range, around 20 °C. So it is no longer suitable in present optical precision measurements. To solve this problem, we propose a refractive index measurement system based on phase step interferometer with three frequency stabilized lasers (532 nm, 633 nm, 780 nm), corrected coefficients of the humidity are measured and a corresponding revised humidity correction equation is acquired. Meanwhile, the application temperature range is extended from 14.6 °C to 25.0 °C. The experiment comparison results at the temperature of 22.2–23.2 °C show the accuracy by the presented equation is better than that of Boensch and Potulski.

Exploring the potential of clumped isotope thermometry on coccolith‐rich sediments as a sea surface temperature proxy

AbstractUnderstanding past changes in sea surface temperatures (SSTs) is crucial; however, existing proxies for reconstructing past SSTs are hindered by unknown ancient seawater composition (foraminiferal Mg/Ca and δ18O) or reflect subsurface temperatures (TEX86) or have a limited applicable temperature range ( ). We examine clumped isotope (Δ47) thermometry to fossil coccolith‐rich material as an SST proxy, as clumped isotopes are independent of original seawater composition and applicable to a wide temperature range and coccolithophores are widespread and dissolution resistant. The Δ47‐derived temperatures from <63, <20, <10, and 2–5 μm size fractions of two equatorial Pacific late Miocene‐early Pliocene sediment samples (c1; c2) range between ∼18 and 29°C, with c1 temperatures consistently above c2. Removing the >63 μm fraction removes most nonmixed layer components; however, the Δ47‐derived temperatures display an unexpected slight decreasing trend with decreasing size fraction. This unexpected trend could partly arise because larger coccoliths (5–12 μm) are removed during the size fraction separation process. The c1 and <63 μm c2 Δ47‐derived temperatures are comparable to concurrent SSTs. The <20, <10, and 2–5 μm c2 Δ47‐derived temperatures are consistently cooler than expected. The Δ47‐ temperature offset is probably caused by abiotic/diagenetic calcite present in the c2 2–5 μm fraction (∼53% by area), which potentially precipitated at bottom water temperatures of ∼6°C. Our results indicate that clumped isotopes on coccolith‐rich sediment fractions have potential as an SST proxy, particularly in tropical regions, providing that careful investigation of the appropriate size fraction for the region and time scale is undertaken.

Investigation of temperature variations on analog/RF and linearity performance of stacked gate GEWE-SiNW MOSFET for improved device reliability

In this paper, reliability issues of Stacked Gate (SG)-Gate Electrode Workfunction Engineered (GEWE)-Silicon Nanowire (SiNW) MOSFET is examined over a wide range of ambient temperatures (200–600K) and results so obtained are simultaneously compared with conventional SiNW and GEWE-SiNW MOSFET using 3D-technology computer aided design quantum simulation. The results indicate that two temperature compensation points (TCP) are obtained: one for drain current (Ids) and other for cut-off frequency (fT) where device Figure Of Merits (FOMs) become independent of temperature, and it is found at 0.65V in SG-GEWE-SiNW in comparison to other devices, hence will open opportunities for wide range of temperature applications. Furthermore, significant improvement in Analog/RF performance of SG-GWEW-SiNW is observed in terms of Ion/Ioff, Subthreshold Swing (SS), device efficiency, fT, noise conductance and noise figure as temperature reduces. It is also observed that at low temperature SG-GEWE-SiNW unveils highly stable linearity performance owing to reduced distortions. These results explain the improved reliability of SG-GEWE-SiNW at low temperatures over GEWE-SiNW MOSFET.

Thermal behaviour and stability of the Arboform® LV3 nature liquid wood

Liquid wood (LW) Arboform® is a novel bio-polymer class of materials consisting in various amounts of lignin, natural fibres, and bio-based additives being a fully biodegradable composite. The full acceptance of LW by industry depends on thermo-mechanical stability as a basic quality condition for engineering applications. The paper aims to investigate the thermal properties and stability of LV3 Nature (LV3) as the uppermost member of Arboform® class of materials under different conditions (i.e. heating rates) both as primary and processed material. The results are discussed in terms of differential scanning calorimetry (DSC) and infrared (IR) spectrometry analysis. DSC thermograms highlight specific changes in corresponding areas and peak positions revealing the polymer behaviour: higher heating rate results in higher activation energies and delays of both endo and exothermic reactions in the temperature range of applications. The FTIR spectra of primary granules and processed LV3 Arboform® show maintaining of the initial functional molecular groups supporting a positive response of the material towards reuse. SEM investigations confirm liaising of the processed composite: no changes at the matrix/fibres interface were found. The results create opportunities in process technologies and applications development of this lignin matrix composite material as a candidate for thermo-plastics polymers.

Recent Advances in Viscoelastic Surfactants for Improved Production From Hydrocarbon Reservoirs

Summary Viscoelastic surfactants (VES) are used in upstream oil and gas applications, particularly hydraulic fracturing and matrix acidizing. A description of surfactant types is introduced along with a description of how they assemble into micelles, what sizes and shapes of micelles can be formed under different conditions, and finally how specific structures can lead to bulk viscoelastic-solution properties. This theoretical discussion leads into a description of the specific VES systems that have been used over the last 20 years in improved oil recovery for upstream applications. VES-based fluids have been used most extensively for hydraulic fracturing. They are preferred over conventional polymer-based fracturing-fluid systems because they are essentially solids-free systems that have demonstrated less damage to the reservoir-rock formation. In fact, approximately 10% of the fracturing treatments use VES-based fluids. Important advancements in VESs have been made by introducing “pseudocrosslinking agents,” such as nanoparticles, to enhance the viscosity. Fracturing-fluid systems modeled after VES have also been improved recently by developing internal breakers to lower their viscosity to flow back the well. The flexibility of VES-based fluids has been demonstrated by their application as foamed fluids, as well as their incorporation with brine systems such as produced water. A second key area that has benefited from VES-based systems is matrix acidizing of carbonate-based reservoirs. The viscosity of these VES-based fluids is mostly controlled by pH; at low pH (low viscosity), the acid system flows easily and invades pore spaces in the formation. During acidizing, the acid is spent, and the pH and viscosity increase. Because the spent acid has higher viscosity, fresh acid is diverted to low-permeability, uncontacted zones and penetrates the rocks to form wormholes. A number of experimental studies and field applications to these effects have been performed and will be described in this study. In order for VES-based fluids to play a more-prominent role in the field, inherent limitations such as cost, applicable temperature range, and leakoff characteristics will need to continue to be addressed. If we can efficiently and economically overcome these issues, VES-based fluids offer the industry an excellent clean and nondamaging alternative to conventional polymer-based fluids.

Electrocaloric response in a relaxor ferroelectric polymer at temperatures far below the dielectric maximum

ABSTRACTRelaxor ferroelectric polymer poly(vinylidene fluoride–trifluoroethylene–chlorofluoroethylene) (P(VDF-TrFE-CFE)) and its blends have been shown to exhibit a giant electrocaloric effect (ECE) over a broad temperature range, e.g. from 0 to 50 °C. Here, a special calorimeter was designed to directly characterize the heat absorbed QECE due to ECE cooling of the blend of P(VDF-TrFE-CFE) with P(VDF-TrFE) 65/35 mol% copolymer down to −15 °C, which covers the temperature range for many refrigeration applications. From QECE, the isothermal entropy change ΔS and adiabatic temperature change ΔT are deduced. The data reveal that at −15 °C the relaxor terpolymer/copolymer blend generates ΔS = 23.0J kg−1 K−1 and ΔT = 5.1K under 100 MV/m, which are still more than 65% of the ECE at room temperature. This temperature is far below the dielectric peak temperature of the relaxor blend and the results reveal the promise of the relaxor polymers for a broad range of EC cooling applications.

Pt-plating effect on La-TZM alloy high temperature oxidation behavior

Pt coating on La-TZM alloys can effectively hinder the matrix alloy oxygen corrosion during high temperature oxidation processes. Doping powder metallurgy was used to prepare La-TZM alloy plates (doped with lanthanum), and electroplating was utilized to deposit a platinum coating on the plate surface. After high temperature treatment of the Pt-coated La-TZM alloy samples at different times and temperatures, scanning electron microscopy and energy dispersive spectra analysis of the sample surface and cross-sections were performed to observe the microstructure and composition changes. Differential thermal analysis of the Pt-coated La-TZM alloy specimens after high temperature treatment was performed to assess the high temperature oxidation resistance of the coated matrix alloy. The results show that the oxidation resistance of the TZM alloy can be enhanced, expanding its temperature application range.

Explore the Failure Mechanism(s) in Lithium-Ion Batteries By Forensic Analysis Techniques

To understand the root cause(s) of a field accident in lithium-ion battery product is important because we always need to know what to result in the unexpected failure in order to solve the safety problem. However, to identify the root cause and failure mechanism behind failure(s) in lithium-ion batteries is always a challenge due to two reasons. First of all, the evidence may be burned or destroyed while the failure occurs. And secondly, there are usually multiple contributing factors coming together to result in a battery failure, so the failure mechanism could be very complex to be identified and simulated exactly. To address the complicated situation, the methodology with a series of forensic analysis techniques could be implemented to explore all potential root causes that are related to the weakness or issues in battery design, quality and aging effects. A practical strategy to identify the potential causes of a battery failure is given in Figure 1. To analyze the failure, all of the detailed background information, such as the environmental conditions, system operation status while failure occurs and all data recorded by the battery management system, will need to be collected as the basis to logistically make the basic hypothesis. To validate the assumptions, the forensic analysis methodology will be the best way to find out the scientific evidences. Furthermore, the simulation of all conditions to duplicate the field event will sometimes be the strong evidence to provide a more solid conclusion regarding the failure mechanisms in a real battery accident. A good example of investigation project using the forensic analysis techniques to study the battery field event is the Boeing 787 battery accident that the aft battery caught fire in January 2013 at Logan International Airport. The cell design was investigated thoroughly by reverse engineering, analytical techniques, non-destructive and destructive analysis, and simulation of abuse conditions to correlate between the root causes and safety behaviors under various operating conditions. All of the key findings and potential root causes are summarized in Figure 2. In this investigation project, the weakness points and potential concerns in the product design, from materials and components to cell and battery levels, were all studied and analyzed because the failure can most likely to be triggered due to the weakness point in the product design or incompatible items between the battery performance and application scope. For example, the battery is expected to be used under low temperature down to -18oC and high temperature up to 70oC; however, the conductivity of the electrolyte will reduce 30% due to the increasing in electrolyte viscosity under -18oC. This will cause the polarization and induce heating effect under extremely high rate application such as the APU engine start in 787 airplanes. In addition, the accelerating rate calorimetry (ARC) study also shows the self-heating in cell can potentially be triggered at low temperature range 60-70oC. This is also the item that cannot match with the application scope exactly. Besides the issues in the application temperature range, there are also other safety concerns in the battery design, such as the inappropriate design in cell terminals to result in localized hot point, and the uneven stress in compressed jelly-rolls to cause the deformation in jelly-rolls and unbalancing current density distribution. After all potential contributing factors to the battery failure were identified, some simulation work in battery system level, including nail penetration test to study the cell-to-cell thermal runaway path and simulation of APU start cycles to explore the local heating effect in terminals, were also implemented and the outcome of the study can help to successfully find out the potential failure mechanisms and possible root causes in the 787 battery incident. In this study, we focus on the investigation of the battery failures based upon the analysis in weakness points in battery designs, effects of variation or anomaly in battery quality and the compatibility issues between the battery characteristics and application scope. The key forensic analysis techniques will be introduced and the rationales to link the correlations between failure mechanism and battery failure modes will also be presented. Not only the lesson learned from the Boeing 787 battery, but also some more case studies of failure analysis will further be demonstrated to provide more insights in the safety behaviors for lithium-ion batteries. Figure 1

Thermo-physical properties of water and ethylene glycol mixture based SiC nanofluids: An experimental investigation

The mixture of water and ethylene glycol (EG) is a kind of traditional heat transfer fluids commonly used in many energy systems to retain the good heating (or cooling) ability of water, as well as broadening the operating temperature range for energy applications. Therefore, the enhancement of water/EG mixture thermo-physical properties by using nanoparticles would be beneficial for the performance of the energy systems. With the purpose of filling the research gap in the literatures, this paper presents experimental data of thermal conductivity and viscosity properties of water/EG-based SiC nanofluids. It was found that the thermal conductivity of nanofluids increased with the volume fraction, and the highest thermal conductivity enhancement was found to be 33.84% for 1.0vol% nanofluid at 20°C. The prepared SiC nanofluids behaved Newtonian behavior and the viscosities decreased with the increasing temperature. In addition, the heat transfer benefits suggested that the water/EG-based SiC nanofluids had potential applications for energy systems, which indicated promising capability of this kind of nanofluids for further heat transfer characteristics investigation.

Influence of thermal losses on the incidence angle modifier factorization approach

Solar thermal applications for industries must be designed to operate at high temperature levels; however, the thermal dependency of the accuracy of the incidence angle modifier factorization has not been sufficiently analyzed. In this study, the annually delivered energy based on both factorized and non-factorized incidence angle modifier values were compared with each other. The integration was conducted for a typical meteorological year in Seville and Stockholm. Four collector types were considered: evacuated tube collector, MaReCo collector, Fresnel collector, and CCStaR collector. Thermal process parameters were shown to have an influence on the error made by the factorization approach; however, within the economically viable temperature range of an industrial heat application, this influence is not significant.

Investigation of asymmetric high-k underlap spacer (AHUS) hybrid FinFET from temperature perspective

This paper estimates the novelty aspects of asymmetric high-k underlap spacer (AHUS) hybrid FinFET devices over conventional FinFET. The AHUS hybrid FinFET combines three advanced technologies i.e., ultra-thin-body (UTB), FinFET and asymmetric high-k spacer on a single silicon on insulator (SOI) platform. This architecture as compared to conventional FinFET further enables the enhancement in device performances without increasing the chip area. Recently, high-k dielectric spacer materials are of research interest due to their better electrostatic control and more immune towards short channel effects (SCEs) in nanoscale devices. This work introduces an asymmetric single layer high-k dielectric spacer in the underlap regions of a hybrid FinFET and claims an effective improvement in low bias applications. We also evaluate the sensitivity of the performance metrics towards temperature (T) variation ranging from 200 to 350 K for the AHUS hybrid FinFET. This further validates the temperature dependency of the proposed device and its application opportunities comprise in modeling analog/RF circuits for a wide range of temperature applications.