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Abstract: Rapid heating of a liquid by a thin film heater surface may initiate homogeneous nucleation of vapor in the liquid in contact with the surface. In such circumstances, nucleation is generally expected to be most likely in the hottest liquid closest to the surface. It is known, however, that in many cases the liquid molecules closest to the surface will experience long-range attractive forces to molecules in the solid, with the result that the equation of state for the liquid near the surface will differ from that for the bulk liquid. In the investigation summarized here, a statistical thermodynamics analysis was used to derive a modified version of the Redlich–Kwong fluid property model that accounts for attractive forces between the solid surface molecules and liquid molecules in the near-wall region. In this model, the wall–fluid attractive forces are quantified in terms of Hamaker constants. This feature makes it possible to assess the effect of wall–fluid force interactions on the spinodal conditions for a variety of fluid and surface material combinations. The variation of pressure near the wall predicted by this model agrees well with the predictions of a hydrostatic model and molecular dynamics simulations. The results of the thermodynamic model analysis indicate that force interactions are important for a wide variety of fluids only within a few nanometers of the solid surface. The model specifically predicts that these forces increase the spinodal temperature in the near-surface region. The implications of this increase for nucleation near a solid surface during rapid heating are explored for circumstances similar to those in inkjet printer heads. The results of the analysis imply that during rapid transient heating, wall effects can result in homogeneous nucleation occurring first at a location slightly away from the solid surface. The results further suggest that on rough surfaces, wall effects may play a role in making some cavities preferred sites for homogeneous nucleation. [Copyright &y& Elsevier]

Abstract: We report on the crystallization of silicon films by the joule heating method using Cr strip heater. We report on the lateral crystalline grain growth of silicon thin films by induced holes fabricated in Cr strip. A temperature gradient is generated by the holes, which causes lateral crystalline grain growth. The duration of the electrical current flow in the Cr strip heater is 5 μs. The crystallization experiment is evaluated by Raman scattering spectra in particular by analyzing the sharp crystalline TO phonon peak around 517 cm−1. [Copyright &y& Elsevier]

In this paper, we studied characteristic behavior of Pt48.75Pd9.75Cu19.5P22 metallic glass during rapid heating. We first rapidly heated a cylindrical specimen of 2 mm in diameter and 5 mm in height by induction heating at a rate of up to 100 K/s. During the heating, glass transition temperature Tg and the crystallization temperature Tx increase with increasing heating rate. The material exhibits a Newtonian viscous flow in the supercooled liquid temperature range, and the normal viscosity decreases with increasing heating rate. The normal viscosity is 2×103 Pa s at a heating rate of 100 K/s. We developed a new microforming system as an application of this phenomenon. The system consists of a rapid resistance-heating unit for foil specimens, a glass transition detector, a linear actuator for driving a tool, and the associated control circuits. With this apparatus, we transferred a three-dimensional micro-shape to the materials within 30 s. A conventional superplastic forging system requires a long time to heat work specimens and to deform them. The developed system thus facilitates mass production of micro parts for micro electro mechanical systems (MEMS). [Copyright &y& Elsevier]

Time profiles of weight change of coal samples and the evolution of low molecular weight gases (H2, CH4, CO and CO2) in both steam gasification and pyrolysis of Yallourn brown coal and Taiheiyo subbituminous coal were measured using a thermobalance reactor with a micro GC and a mass spectrometer, in order to examine the reaction mechanism of steam gasification with rapid heating (100 K s−1). It was found that, in the case of slow heating, steam reacted with metaplast and promoted the evolution of tar above 623 K and that a water shift reaction took place above 873 K. Steam gasification of produced char occurred above 1023 K, increasing the evolution of CO, CO2 and H2. When the heating rate was high, steam reforming of volatile matter and steam gasification of metaplast took place parallel to metaplast formation and condensation. The char produced by pyrolysis was almost completely gasified and converted into H2 and CO2 by steam. The chemical energy of coal was mainly converted into hydrogen energy and the gasification efficiency was slightly increased by rapid heating (i.e. 100 K s−1). [Copyright &y& Elsevier]

The unsteady-state thermal conduction process in single-mode (SM) optical fiber was studied theoretically with the explicit finite-difference method (FDM). In the numerical calculation it was assumed that the electrical conductivity of the core layer increased rapidly above 1323 K. The core-center temperature changed suddenly and reached over 3×105 K when an optical power of 1 W was input into the core layer heated at 1373 K. This rapid heating of the core initiated the "fiber fuse" phenomenon. The high-temperature core areas, whose radiation spectrum extended over a wide range from the infrared to the ultraviolet regions, were enlarged and propagated toward the light source at a rate of about 0.7 m s-1. This rate was in fair agreement with the experimentally determined value. [ABSTRACT FROM PUBLISHER]

The effects of rapid heating cyclic heat treatment on mechanical properties of a TiAl-based alloy (Ti-33Al-3Cr) were studied by means of an induction heating machine. The results show that: 1) fine fully-lamellar microstructure with colony size of about 50 µm and lamellar spacing of about 0.12 µm can be obtained; 2) the compression mechanical properties can be improved to a large extent and the best comprehensive compression mechanical properties can reach the yield stress 745 MPa, the large flow stress 1 672 MPa and the compression ratio 19.4%; and 3) the compression fracture at room temperature after induction heat treatment and aging is still typical cleavage fracture. [ABSTRACT FROM AUTHOR]

Measurements of the bulk magnetic properties for two non-oriented electrical steels after a rapid heating are reported. A deterioration of the magnetic properties was observed for the fully processed non-oriented grade and an improvement for the semi-processed non-oriented grade. This publication emphasizes the effects due to the competition between the increase of the grain size and the appearance of thermal stresses during the rapid heating on the magnetic properties of the steels. [Copyright &y& Elsevier]

The response of inertinite-rich Witbank coals (South Africa) to rapid heating was evaluated using petrography, selected Nuclear Magnetic Resonance (NMR) and X-Ray Diffraction (XRD) structural parameters. A total of thirteen (13) coal samples were collected from the No. 2 Seam; a set of six (6) samples from the western and the eastern sides of a ~ 0.4 m thick dolerite dyke emplaced into the coal seam at 0.25 m intervals. An unaltered coal (Un-C; the 13th sample), collected away from the dyke but within the same seam at the mine, was included for comparison. All 13 coal samples were dominated by inertinite. Semifusinite was most abundant in the samples from the western side of the dyke, whereas the proportion of inertodetrinite was highest in samples from the eastern side. Due to very low vitrinite contents, mean random total reflectance (%RoTmr) was used to compare the maturity of the inertinite-rich coals. A decrease in volatile matter was correlated with an increase in mean random total reflectance (%RoTmr; measured on semifusinite, inertodetrinite, and vitrinite), the latter used as a potential maturity indicator for the thermally altered inertinite-rich coals. Mean random total reflectance rose from a background value of 1.52%RoTmr (for Un-C) to 2.83%RoTmr for the coal sample at the western coal-dyke contact (0.0 m). The corresponding reflectance values for the thermally altered coals from the eastern side were less consistent, decreasing closest to the dyke (1.93%RoTmr for the sample at 0.0 m); this trend is also reflected in the NMR and XRD parameters. Eight (8) samples were selected for the NMR analysis, representative of the maceral composition and maturities of the coals investigated. For Un-C, the fraction of aromatic carbons (fa) was 0.88 (average number of carbons per aromatic cluster (C) = 17), and the interplanar spacing (d002) was 3.48 Å (with a crystallite height of 22.09 Å). For the thermally altered coals from the western side, fa decreased from 0.96 at the coal-dyke contact (C = 26 for sample at 0.0 m) to 0.92 for the sample at 1.25 m from the dyke (C = 20). For samples from the eastern side, fa increased from 0.91 (C = 19 for the sample at 0.25 m) to 0.93 (C = 23 for sample at 0.5 m), before decreasing to 0.89 further from the dyke (C = 18 for sample at 1.25 m). In general, the d002 values for the thermally altered coal samples were larger than for graphite. Similarly, only marginal increases in crystallite heights were observed. Although the dyke induced coal maturation and the resultant increase in fa , the overall lack of graphitic order in the thermally altered coals was ascribed to the limited thermal energy provided by the relatively thin dyke; increased heat input would be required to effect significant structural changes in the inertinite-rich coals. Differences between the two sets of thermally altered coal samples were attributed to the emplacement dynamics of the igneous intrusion, which require further investigation. [ABSTRACT FROM AUTHOR]

Interactions between energetic material relevant nanoscale metal oxides (SiO 2 , TiO 2 , MgO, Al 2 O 3 , CuO, Bi 2 O 3 ) and poly(vinylidene fluoride) (PVDF) at high temperature were investigated by temperature-jump/time-of-flight mass spectrometry (T-jump/TOFMS) and thermogravimetric-differential scanning calorimetry (TGA-DSC). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the morphology of the compositions, while X-ray diffraction (XRD) was utilized to analyze the condensed phase crystalline species at temperatures of interest. The exergonicity and exothermicity of HF gas with hydroxyl-terminated metal oxide surfaces make HF the likely fluorine-bearing moiety and primary mode of the fluorinating reactions, where terminal OH - configurations are replaced by F - in the formation of a stronger metal-fluorine bond. However, not all compositions produce corresponding stable metal fluoride. The results show that while some of the investigated metal oxide-PVDF compositions enhance PVDF decomposition and release HF in larger quantities than PVDF, others release HF in smaller quantities than PVDF and even retard PVDF decomposition. The former compositions demonstrate exothermic, multistep mass loss modes prior to neat PVDF mass loss, and the relative intensity of HF gas increases as the temperature of the release point decreases, implying a correlation between HF release and the progression of exothermic behavior. An interplay dynamic where surface interactions both lower the onset of HF release and engage exothermically with HF gas subsequently is proposed.

Calcium substituted lead titanate thin films have been prepared by a sol-gel method, deposited by spin-coating, and thermally treated so as to obtain a perovskite structure. Two types of thermal treatments were given, differing in the heating rate, which in conventional treatments was of some 10°C/min, and in rapid treatments >500°C/min. With rapid heating, materials are obtained in which greater polarizations are commuted and bias fields are smaller. This, together with the fact that additional (undesired) phases are not observed by X-ray diffractometry when rapid treatments are used, shows that these are to be preferred over conventional treatments. [ABSTRACT FROM AUTHOR]

A new technique of rapid heating in high-temperature thermomicroscopic analysis is suggested. The apparatus is described, the metrological features of the method and its advantages and limitations are discussed. Application of the technique to studying the behaviour of refractory Nd3S4, GaP and MoS2 compounds in the temperature range from 25 to 2500°C shown. [ABSTRACT FROM AUTHOR]

Results are provided for development and study of radio engineering heat-shielding composite materials. The main properties of composite materials of the SiO-SiO class are demonstrated, and strength and thermophysical properties are determined over the whole working temperature range. Results are presented for a study of improvement of heat-resistant materials of the SiO-SiO class. The effect of refractory oxides ZrO and CrO introduced into the material structure by means of water-soluble precursors on short-term heat resistance is shown. Comparative tests are performed for the original and modified material on heating in a high-temperature gas flame, and the results obtained are evaluated. [ABSTRACT FROM AUTHOR]

A heating strategy has been developed for the battery operated at low temperature, which can intelligently control the thermal storage and release of an inorganic phase change material (PCM): CaCl2·6H2O - carboxymethyl cellulose (CMC). With the 0.5 wt % CMC content, this PCM (melts at 25–30 °C) becomes stable in the subcooled state, making it possible to be used as the subcooled liquid at 5 °C to store the heat generated by the battery. The thermal energy stored in the subcooled PCM can be detonated to release by triggering the PCM to crystalize with a special device. The instant crystallization of this subcooled PCM heats the battery rapidly-which is at a rate up to 7.5 °C/min, higher than the battery without PCM (0.8 °C/min) or the battery with the no subcooled PCM(0.4 °C/min). The discharge capacity and power can be improved by 9.87% and 7.56%. This work presents a new method of heating by switching the subcooling of PCM on/off, which extends the application of PCMs to battery heating under low temperatures. This energy-free but efficient method could provide a better alternative to most active heating systems. Image 1 • A passive but rapid battery heating strategy with thermal release of subcooled PCM. • The stable subcooling of PCM was used to preserve the latent heat. • An effective trigger device for solidification of subcooled PCM is designed. • The heating rate of this method is up to 7.5 °C/min. • The discharge capacity and power of the battery were improved by 9.87% and 7.56%. [ABSTRACT FROM AUTHOR]

Co-combustion of biomass offers a great potential to reduce CO 2 emissions but rarely mentioned co-combustion behavior of pelletized coal-biomass mixtures and inconclusive results based on single determinants formed obstacle for industrial application. In this study, ignition and flame characteristics, reaction and kinetic parameters and pollutant generation path were comprehensively investigated. Intrinsic combustion experiments were carried with the gas phase maintaining at room temperature in a concentrating photothermal reactor at heating rate over 200 °C/s. Same "homogeneous" ignition was evidenced while advanced devolatilization but more intense slagging behaviors were identified with the increase of biomass proportion. With the biomass proportion increased from 0% to 40%, the activation energies during devolatilization to ignition decreased non-linearly from 47.44 kJ/mol to 8.03 kJ/mol, indicating the existence of synergistic effect. CO exhibited relative high generation rates and the generation rate increased with the biomass content. Three fitted CO peaks were identified during co-combustion, which were contributed by devolatilization of coal and biomass, and combustion of char, respectively. First increased and then decreased NO emission with the increase of biomass proportion was evidenced for the higher N content in biomass but enhanced reduction by char and NH radicals with higher biomass proportion. • Co-combustion behaviors (ignition, slagging, kinetic and pollutant) were studied • The Ea decreased non-linearly from 47.44 kJ/mol to 8.03 kJ/mol with biomass addition • CO exhibited high intrinsic generation rate and biomass formed an independent CO peak • Biomass enhanced primary fuel-N emission and NO reduction by char and NH radical • Synthetic effects were proved by combustion characteristics and kinetic analysis [ABSTRACT FROM AUTHOR]

In this study, the combined effect of dislocation density and rapid thermal cycling on the tempering kinetics of fully martensitic steel has been investigated by straining the sheets to different deformation levels. It was found that the strain-induced dislocations created more nucleation sites for carbide precipitation, and decreased carbide growth time. Strain-enhanced precipitation caused the carbide morphology to change from elongated to small quasi-spherical precipitates. Plastic deformation also accelerated the decomposition of carbides and film-like retained austenite in the as-received martensite laths. After tempering the deformed martensite had higher microhardness than tempered unstrained martensite, resulting from finer and semi-coherent precipitates, a high retained dislocation density, and the presence of untempered and partially tempered martensite blocks. Unlabelled Image • Martensitic steel was rapidly tempered with prior plastic deformation. • Plastic deformation created more precipitate nucleation sites and suppressed growth. • The morphology of precipitates changes from elongated to quasi-spherical. • Semi-coherent precipitates were obtained in deformed and rapidly tempered martensite. • The prior plastic deformation improved tempered martensite strength. [ABSTRACT FROM AUTHOR]

Rapid thermal processing strategies, i.e. thermal histories that involve high heating rates, short times at peak temperatures, and subsequent rapid cooling by quenching, and that typically require significantly shorter total processing times than are utilized in conventional sheet steel processing, are reviewed to illustrate potential benefits and challenges for the production of new advanced high strength steel grades. A fundamental framework based on conventional induction heat treating often applied to rapidly selectively harden surfaces of steel components is highlighted to provide a basic structure for assessment of rapid thermal processing of sheet steels. Four sheet steel product groups were considered. These include dual-phase (DP) steels, quenched and partitioned (Q&P) steels, flash processed steels, and press hardened steels. In comparison to conventionally heat-treated steels, rapid processing of steels resulting in multi-constituent microstructures consisting of ferrite and martensite (DP) and also containing retained austenite (Q&P) result in enhanced strength-ductility combinations primarily due to microstructural refinement. Results indicate that flash processed and press hardening steels, both with primarily martensitic microstructures, exhibit properties largely similar to conventional quenched and low-temperature-tempered steels. • Rapid thermal processing refines heat-treated steel microstructures. • Induction and flash processing may lead to primarily martensitic microstructures. • Dual-phase and quenched and partitioned steel properties enhanced by rapid processing. [ABSTRACT FROM AUTHOR]

1D vanadium pentoxide materials have been extensively studied because of their fascinating properties and versatile applications. If they could be manufactured on a large scale, 1D V 2 O 5 materials would be attractive for more commercial applications. In this work, we report a novel rapid-heating-assisted polymerization strategy to prepare 1D V 2 O 5 /PEDOT core-shell nanobelts. By rapid heating the freeze-dried V 2 O 5 hydrogel, we can immediately obtain large quantities of uniform V 2 O 5 nanobelts with high purity. After coating an ultrathin PEDOT skin, the resultant 1D V 2 O 5 /PEDOT core-shell cathode exhibits excellent rate performance and superior cycling stability, as compared to the commercial V 2 O 5 powders. We present an important approach toward mass-producing 1D V 2 O 5 nanomaterials and can be extended to preparing other 1D materials for potential applications ranging from electronics to energy conversion and storage. [ABSTRACT FROM AUTHOR]

When hot forging 7075 aluminum alloy, as a military material durable enough for most of its applications, it needs to be heat-treated to ensure the target material property achieves the application requirements. However, the material properties change because of heat throughout usage. In this study, a new approach was devised to heat treat the alloy to prevent material property changes. The study further clarified the effect of rapid heat treatment on the high-temperature resistance of a hot forging 7075 aluminum alloy. Infrared (IR) heat treatment was used as a rapid heating technique to effectively replace the conventional resistance heat (RH) treatment method. Our experimental result showed that IR heat treatment resulted in better age hardening at the initial aging stage, where its tensile strength and elongation appeared like that of a resistance heat treatment. More so, based on hardness and tensile test results, the IR-heated treatment process inhibited the phase transformation of precipitations at a higher temperature, improving high-temperature softening resistance and enhancing the thermal stability of the hot forging 7075 aluminum alloy. [ABSTRACT FROM AUTHOR]

The aim of this review is to discuss the applications of microwave heating to separation and purification processes in chemical engineering from the perspective of its three unique features, namely rapid heating, selective heating and specific microscopic effects. These features render microwaves an alternative clean energy source that can replace or complement the conventional heating in various separation processes. The rapid heating and evaporation of water under the influence of microwaves renders the technology valuable in materials drying and organic extraction. The direct and selective heating of materials with high dielectric loss in a mixture enables energy savings in the treatment of petrochemical products. In adsorption processes, microwave heating can selectively heat solid adsorbent material leading to the formation of micro "hot spots" (localized zones of high temperature), increasing the efficiency in adsorbent regeneration. Finally, a deeper understanding of the impact of microwaves on microscopic structure has led to novel separation methods, such as microwave-assisted pervaporation and microwave-assisted reactive distillation. An overview of the key mechanisms and developments of microwave heating in all these applications during the recent five years is provided and is followed by identification of the associated challenges in scale up. Fundamental research is still required for guiding further industrial application, while numerical simulations considering both heat transfer and distribution of the electromagnetic field in various reactor geometries can be helpful in the design of microwave reactors for large scale applications. Image 1 • The unique features of microwave heating render the technology a promising tool for Process Intensification. • Application of microwaves to diverse separation processes in the last five years have been summarized. • The underlying mechanisms of microwave-assisted separations are discussed. • The challenges and limitations of microwave-assisted techniques, requiring further research are highlighted. [ABSTRACT FROM AUTHOR]

The invasive brown marmorated stink bug, Halyomorpha halys, is causing economic and ecological damage in invaded areas. Its overwintering behavior warrants mitigation practices in warehouses and shipping operations. The aim of this study was to characterize the mortality response curves of H. halys adults to short high-temperature exposure. Here we compared field-collected individuals entering (ENA) and exiting diapause (EXA). EXA adults displayed increased susceptibility to high temperatures compared to ENA individuals. Complete mortality of all tested individuals was obtained after 10 min exposure at 50.0 °C, and after 15 (EXA) or 20 min (ENA) at 47.5 °C. The nutritional status of these insects had no effect on high-temperature tolerance. The mortality curves obtained here may be used for the definition of cost-effective heat treatments aimed at the H. halys control. [ABSTRACT FROM AUTHOR]

• Phase transformation of Nb 3 Al wires RHQ at the T c peak and valley was compared. • Nb 3 Al wires annealed at 800 °C get the highest T c and J c when RHQ at the T c peak. • Annealed at 900 °C can get best T c and J c of Nb 3 Al wires quenched at the T c valley. This work compared the phase transformation feature and superconducting properties of Nb 3 Al wires rapidly heated at 272 A and 315 A, closing to the Tc peak and valley current condition, respectively. The fabricated rapidly heating, quenching and transformation (RHQT) Nb 3 Al wires are mainly consisted of A15 phase with trace Nb and Nb 2 Al impurity phase. With the increase of annealing temperature from 700 °C to 1100 °C, the T c value and J c performance of Nb 3 Al wires improve first and then gradually decrease. M-T and J c- H curves reveal that the best T c and J c performance of 272 A samples was obtained at the annealing temperature of 800 °C, compared to that of 900 °C for the 315 A samples. In both 272 A and 315 A samples, lower annealing temperature cannot promote the phase transform process from bcc to A15 phase. Excessive heating beyond 1000 °C caused the already transformed Nb 3 Al phase to decompose into Nb 2 Al and Al-poor Nb 3 Al phase, resulting in degraded T c and J c performance of the Nb 3 Al wires. The main pinning mechanism of Nb 3 Al wires was grain boundary pinning, as deduced from the fitting of flux pinning force versus applied field curves. [ABSTRACT FROM AUTHOR]

Thermal nanoimprint lithography is playing a vital role in fabricating micro/nanostructures on polymer materials by the advantages of low cost, high throughput, and high resolution. However, a typical thermal nanoimprint process usually takes tens of minutes due to the relatively low heating and cooling rate in the thermal imprint cycle. In this study, we developed an induction heating apparatus for the thermal imprint with a mold made of ferromagnetic material, nickel. By applying an external high-frequency alternating magnetic field, heat was generated by the eddy currents and magnetic hysteresis losses of the ferromagnetic nickel mold at high speed. Once the external alternating magnetic field was cut off, the system would cool down fast owe to the small thermal capacity of the nickel mold; thus, providing a high heating and cooling rate for the thermal nanoimprint process. In this paper, nanostructures were successfully replicated onto polymer sheets with the scale of 4-inch diameter within 5 min. [ABSTRACT FROM AUTHOR]

Fast charging is a key enabler of mainstream adoption of electric vehicles (EVs). None of today's EVs can withstand fast charging in cold or even cool temperatures due to the risk of lithium plating. Efforts to enable fast charging are hampered by the trade-off nature of a lithium-ion battery: Improving low-temperature fast charging capability usually comes with sacrificing cell durability. Here, we present a controllable cell structure to break this trade-off and enable lithium plating-free (LPF) fast charging. Further, the LPF cell gives rise to a unified charging practice independent of ambient temperature, offering a platform for the development of battery materials without temperature restrictions. We demonstrate a 9.5 Ah 170 Wh/kg LPF cell that can be charged to 80% state of charge in 15 min even at -50 °C (beyond cell operation limit). Further, the LPF cell sustains 4,500 cycles of 3.5-C charging in 0 °C with <20% capacity loss, which is a 90× boost of life compared with a baseline conventional cell, and equivalent to >12 y and >280,000 miles of EV lifetime under this extreme usage condition, i.e., 3.5-C or 15-min fast charging at freezing temperatures., Competing Interests: The authors declare no conflict of interest.

Micro process engineering as a process synthesis and intensification tool enables an ultra-short thermal treatment of foods within milliseconds (ms) using very high surface-area-to-volume ratios. The innovative application of ultra-short pasteurization and sterilization at high temperatures, but with holding times within the range of ms would allow the preservation of liquid foods with higher qualities, thereby avoiding many unwanted reactions with different temperature-time characteristics. Process challenges, such as fouling, clogging, and potential temperature gradients during such conditions need to be assessed on a case by case basis and optimized accordingly. Owing to the modularity, flexibility, and continuous operation of micro process engineering, thermal processes from the lab to the pilot and industrial scales can be more effectively upscaled. A case study on thermal inactivation demonstrated the feasibility of transferring lab results to the pilot scale. It was shown that micro process engineering applications in thermal food treatment may be relevant to both research and industrial operations. Scaling of micro structured devices is made possible through the use of numbering-up approaches; however, reduced investment costs and a hygienic design must be assured.