Electrothermal Properties Research Articles

Development of a hybrid anti-icing coating with superhydrophobic and electrothermal properties

<h2>Abstract</h2> This talk presents the simple fabrication and experimental characterization of an energy-efficient hybrid anti-icing coating. The multi-layered coating consists of an electric heating film with a SiO₂ / polydimethylsiloxane (PDMS) superhydrophobic top coating. The heating film is composed of a thin layer of copper-based epoxy, insulated in a PDMS film. The hybrid coating was applied to a 17-4PH stainless steel substrate by a simple sequential spray-coating process. The superhydrophobic coating possessed a static contact angle of 164° and a sliding angle of 3°. Characterization of the heating film demonstrated its fast thermal response, producing a 60 °C temperature rise in 52 s. Icing experiments conducted at −10 °C showed that, when compared to the untreated substrate, the hybrid coating increased the droplet freezing time from 13 s to 63 s and reduced the ice adhesion strength from 284 kPa to 50 kPa. In a simulated spray-icing environment, anti-icing was achieved with a minimum surface power density of 0.26 W/cm². The superhydrophobic coating reduced the energy consumption for anti-icing by 40%. The results show that the hybrid coating has potential for use in industrial applications due to its simple fabrication, high energy-efficiency, and robust anti-icing performance.

Coal tar-derived conductive pigment/polyvinylidene fluoride composite for Joule heating

The fast-increasing demand for high-performance carbon conductive paints has motivated the use of inexpensive precursors and easy-to-manufacture methods to scale up production. The performance of carbon conductive paints highly depends on the precursor types, carbonization conditions and the coordination between carbon pigment and binder. This work investigated the effect of precursors (by-products of coking industry including coal tar pitch, anthracene oil, naphthalene oil, and washing oil) on the structure and properties of carbon pigment, as well as the influences of binders polyvinylidene fluoride (PVDF), styrene-butadiene emulsion, and acrylic emulsion on the electrothermal properties and adhesion of carbon paint coating. The conductive pigment prepared from coal pitch has nano-sheet structure, high sp2 content, large sp2 cluster size and high disordered structure, resulting high carrier concentration and mobility, and low volume resistivity. The carbon conductive coating fabricated from coal pitch-based pigment and PVDF (PC-PVDF) has good electrothermal properties, excellent stability, low volume resistivity, good adhesion and corrosion resistance. The electrical conductivity of carbon-PVDF composites prepared from coal tar pitch, anthracene oil, naphthalene oil, and washing oil as precursors were 15.7, 3.0, 4.4, and 4.0 S/m, respectively. Coal pitch-derived conductive pigment-PVDF carbon coating exhibits excellent Joule heating performance, i.e., up to 147 °C at 20 V when heating at 122 °C/min, uniform temperature distribution, and excellent reusability. This work demonstrates the potential application of coal pitch-based pigment-PVDF coating for Joule heating.

High-performance flexible electrothermal Joule heaters from laser reduced F-N Co-doped graphene oxide with extended Sp2 networks

Phonons play an important role in heat generation and propagation across graphene lattice; however, this is hindered by graphene heteroatom doping which generates highly defected structures. Consequently, heteroatom doping has not been primarily explored in electrothermal materials despite presenting a cost-effective and metal-free method of improving electronic activity in flexible 2D materials. Herein, we present a facile and scalable technique for fabrication of fluorine-nitrogen co-doped laser reduced graphene oxide (FN-G) Joule heaters by ultrasonic wetchemical doping and maskless laser writing method. Films containing 6.14 at. % F and 3.22 at. % N, low sheet resistance of 24.49 O/sq. and uniquely high degree of atomic ordering indicated by an ID/IG of 0.16 were successfully fabricated. The heaters showed highly competitive transient electrothermal behaviour with a saturation temperature of 365 °C for only 9 V applied voltage, high heating rate of 385.33 °C/s, and average response time of 0.68 s. An excellent temperature distribution, low power requirement, and a net-zero degradation in the electrical and electrothermal properties even after 500 bending cycles was demonstrated. These high-performance features render the FN-G heater suitable for applications in wearable electronics powered by low voltage portable electrochemical cells.

Durable superhydrophobic sponge for all-weather cleanup of viscous crude oil by electrothermal and photothermal effects

Creating innovative absorbent materials with a rapid absorption rate and high absorption efficiency for viscous crude oils continues to be a global problem. Hydrophobic/oleophilic porous sorbents with light-to-heat or electric-to-heat capabilities are attractive options for crude oil clean-up, but their complicated preparation processes, poor stability, and variable weather restrict their practical usage. Herein, the light-absorbing and electrical polypyrrole and Fe3O4 are introduced to endow the melamine sponge with excellent photothermal and electrothermal properties, while the polydimethylsiloxane is coated on the surface of the sponge to make it durable, compressible, and superhydrophobic. Thanks to the superior photo/electro-heat conversion capability, the temperature of the as-prepared sponge′s surface may reach 95.9 °C under solar light with 1 kW m−2 intensity or 101.4 °C under a voltage of 11 V, making it adaptable to reduce the crude oil’s viscosity and absorb it in all weather. In addition, when the sponge is exposed to sunlight and voltage at the same time, its crude oil absorption velocity is dramatically improved and is about 107 times greater than that of an unheated sponge. Based on the eco-friendly preparation method and excellent crude oil absorption performance, this work provides a promising absorbent for the recycling of spilled crude oil.

Rapid and Energy-Efficient Frontal Curing of Multifunctional Composites Using Integrated Nanostructured Heaters.

Current technologies for the manufacture of fiber-reinforced polymer composites are energy-intensive, environmentally unfriendly, and time-consuming and require expensive equipment and resources. In addition, composites typically lack key nonstructural functionalities (e.g., electrical conductivity for deicing, lightning strike protection, and structural health monitoring), which are crucial to many applications such as aerospace and wind energy. Here, we present a new approach for rapid and energy-efficient manufacturing of multifunctional composites without using traditional expensive autoclaves, ovens, or heated molds used for curing of composites. Our approach is predicated on embedding a thin conductive nanostructured paper in the composite layup to act as a resistive heater for triggering frontal polymerization of the matrix thermosetting resin of the composite laminate. Upon passing electric current, the nanostructured paper quickly heats up and initiates frontal polymerization, which then rapidly propagates through the thickness of the laminate, resulting in rapid curing of composites (within seconds to few minutes) irrespective of the size of the composite laminate. The integrated nanostructured paper remains advantageous during the service of the composite part by imparting new functionalities (e.g., deicing) to the cured composite, owing to its excellent electrical conductivity and electrothermal properties. In this work, we first study the influence of several composite processing parameters on the electrothermal properties of the nanostructured paper and determine the power required for rapid initiation of frontal polymerization. We then successfully fabricate a 10 cm × 10 cm composite panel within 1 min using only 4.49 kJ of energy, which is 4 orders of magnitude less than the energy consumed by the traditional bulk, oven-curing technique. Detailed experiments are conducted to provide an in-depth understanding of the effect of heater position, tooling material, and input power on frontal curing of composite laminates. The multifunctional response of produced composites is demonstrated by performing a deicing experiment, where a 50 × 50 × 3 mm3 cube of ice is completely melted within 3 min using an input power of 77 W.

High-pressure and high-temperature synthesis of stable SxCo3.6Ni0.4Sb12 skutterudite compounds

Compared to Te, Ni is found in abundance in the earth's crust. At the same time, the mechanical properties of Ni atom-substituted skutterudite are significantly improved. In this study, a series of S-filled Ni-substituted skutterudite compounds were synthesized by a high-pressure and high-temperature (HPHT) method in the synthesis pressure range of 1.0–3.0 GPa. The phase composition, microscopic morphology, and electrothermal transmission properties of the SxCo3.6Ni0.4Sb12 (x = 0, 0.05, 0.10, 0.20) samples were systematically characterized. Phase composition analysis showed that the introduction of S atoms into the intrinsic pores of skutterudite can improve the solid solution limit of Ni atoms in the Co sites of skutterudite. The filling limit of S increased with the synthetic pressure. Moreover, microscopic morphology analysis revealed that the filling of S atoms inhibited the growth of grains. A large number of lattice fringes in different directions were found in the sample, containing abundant microstructures such as lattice distortions and dislocation defects. Compared with the synthesized samples, S0.05Co3.6Ni0.4Sb12 synthesized at 1.0 GPa had a maximum room temperature power factor of 7.98 × 10−4 Wm−1K−2. The electrical properties of S0.05Co3.6Ni0.4Sb12 samples stored for 6 months without any protective measures were tested at room temperature. No obvious changes in performance were observed, which proved that the HPHT method can synthesize stable samples. After several thermal cycles, the electrical properties of the S0.05Co3.6Ni0.4Sb12 sample was tested for variable temperature, and it was found that the sample still had good stability. How the substitution of S atoms with Ni atoms reduces the lattice thermal conductivity can be explained by fitting the Callaway model. The S0.05Co3.6Ni0.4Sb12 sample synthesized at 1.0 GPa had a maximum zT value of 0.46 at the test temperature of 773 K, which decreased to 0.43 after multiple thermal cycles at the same temperature.

Electro-thermal properties and characterization of the flexible polyurethane-graphene nanocomposite films

The flexible film of polyurethane/graphene (PU/G) composition with the different mass fractions of reduced graphene oxide (rGO) was synthesized by the in situ polymerization method and the electrothermal properties of the films were investigated. Results show by increasing the mass fraction of rGO to 5 wt% (PU/G5), the composition goes to the percolation zone. Further, the PU with 20 wt% of rGO (PU/G20) shows good conductivity which is relatively stable at different voltages (∼135 Ω/sq). Moreover, using graphene in the PU matrix has increased its thermal stability. PU/Gs stable up to 200 °C by assisting graphene. Also, the maximum Seebeck coefficient and voltage of PU/Gs (5, 10, 20) obtain at about 45 °C and 85 °C respectively, and PU/G20 has better performance than others. In addition, the electrothermal response of PU/G20 shows good repeatability and could reach 75 °C and 45 °C by applying the 22 V and 12 V respectively. The thermal stability, good electrothermal response, and flexibility of the sample suggest it for electrical heaters and wearable applications.

Electrothermally Activated CNT/GNP-Doped Anti-icing and De-Icing Systems: A Comparison Study of 3D Printed Circuits versus Coatings

The present work studies the electrical and electrothermal properties of CNT/GNP-doped nanocomposites for optimizing their anti-icing and de-icing capabilities. Here, a comparison between 3D-printed circuits and coatings based on these materials is carried out. In this regard, the higher electrical conductivity that is achieved by the specimens when increasing the nanoparticle content and the higher cross-sectional area of the coatings with regard to the 3D-printed circuits induces a higher heat generated by the Joule’s effect. Moreover, the successful de-icing test performed by the specimen with the highest self-heating capability, evinces that the studied nanocomposites are suitable for de-icing purposes.

Experimental design and testing of the electrothermal properties of carbon nanotube film

Electrically heated materials play a critical role in electrically heated textiles, which have potential applications in a wide range of fields for human healthcare. Among them, carbon nanotube film (CNTF) has gained a great deal of attention because of its excellent electrical and thermal conductivity. In this paper, we explored the electrothermal property of CNTF with different sizes and CNTF covered by polyester. It showed that the air temperature had a certain effect on the electrothermal performance of the CNTF. When a voltage of 2.5 V was applied, the 20 mm × 20 mm CNTF sample stored at 25°C achieved the highest temperature of about 37°C, which was 34°C when stored at −20°C. In addition, was observed that adding a polyester protective fabric can prevent heat loss effectively. When a voltage of 5.5 V was applied, the U-shaped CNTF achieved the highest temperature of about 42°C, while the polyester-CNTF achieved about 35°C. Notably, CNTF exhibited rapid temperature response when the voltages were turned on and off. When the voltage was 4.5 V, the 20 mm × 20 mm CNTF reached 50°C in 5 s, and the heating rate was about 10°C/s. When the voltage was turned off, the temperature dropped about 30°C immediately in 5 s. Finally, the relationship between the thermal conductivity of CNTF and its mass and specific heat capacity was constructed using Newton's law of cooling. This provided a model to calculate and predict the performance, which can help to design the power and temperature of electrical heated textiles in the future.

In-situ Joule-heating drives rapid and on-demand catalytic VOCs removal with ultralow energy consumption

The running of environmental purification usually employs massive consumption of energy, and it is of significant scientific importance and real impact to reduce the energy cost in environmental treatments. In particular, it is urgently required to minimalize the energy cost of the catalytic oxidation of gaseous pollutants represented by volatile organic compounds (VOCs). Herein, we develop a rapid in-situ Joule-heating configuration to drive the catalytic VOCs oxidation with ultra-low energy consumption. As a prototypical illustration, atomically dispersed Pt/CeO2 catalyst was decorated on conductive Nickle foam substrate to act as both catalytic and electric components with minimal pressure drop and high compatibility. The catalytic system exhibited 100% conversion toward toluene (1000 ppm, 33 mL min−1) with an ultralow input power of 6.5 W, which was 87% lower than that of a conventional heating furnace. Moreover, the long-term stability, high universality for various VOCs, and responsiveness for real-time changing components were also demonstrated. The outstanding electro-thermal properties of the system can be extended to more gaseous catalytic reactions with much lower energy consumption.

Gradient Response Color‐Changing Joule Heating Fabric for Visual Temperature Detection

AbstractSmart heating textiles with high safety factors are urgently demanded when multitudinous intelligent heater products spring up in wearable electronics. We report a Joule heating fabric with gradient response discoloration for visual temperature detection. The Joule heating fabric exhibits high electrical conductivity, and the surface resistance is around 150 Ω (2 cm). The temperature of Joule heating fabric rapidly rises from room temperature (25.6 °C) to 42.6 °C at 8 V in 160 s and keeps an equilibrium with the environmental temperature based on the electrothermal conversion properties of graphene. Meanwhile, the Joule heating fabric exhibits gradient response discoloration and turns from amaranth (25.6 °C) to blue (33.0 °C) and white (38.0 °C) successively. Once the power is turned off, the Joule heating fabric turns back to the amaranth in 60 s, resulting from the disappearance of Joule heating. These results suggest the temperature change of Joule heating fabric can be visualized via the gradient response color‐changing behavior under the applied voltage. The Joule heating fabric maintains stable electrothermal performance after repeated mechanical deformations and presents favorable durability even undergone over 50 cycles. The Joule heating fabric displays potential in wearable electronics for protecting the human body against scald.

A Temperature-Dependent Physical Thermal Network Model Including Thermal Boundary Conditions for SiC MOSFET Module

SiC MOSFETs have received great attention due to their excellent electrothermal properties. Accurate junction temperature information of SiC MOSFETs ensures safe operation and helps effective thermal management. However, the existing thermal models have limits to correctly predict the thermal behaviors, whose parameter extraction processes are normally complicated. Most of the thermal models generally omit the temperature effects, which greatly impairs their usefulness and effectiveness. Here, a temperature-dependent physical resistor–capacitor ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RC</i> ) network model is proposed, which can accurately characterize the thermal behavior of SiC MOSFETs particularly under high-temperature conditions. Meanwhile, the boundary conditions are fully investigated and modeled, which guarantees the adaptation of the proposed model for different real-field applications. The proposed method can remarkably simplify the process of parameter extraction since only the steady-state temperature distribution information is required with the assistance of finite-element method (FEM). Finally, the effectiveness and the robustness of the proposed model are validated by FEM simulation and experiments.

Ergonomic design and evaluation of carbon nanotube film (CNTF) and metal wire based flexible electrically heated gloves

Electric heating gloves are essential for people working in severe cold environments which could protect their hands warm efficiently. Existing electric heating gloves, however, tend to restrict the movement of the fingers and have limited thermal protection, affecting the working efficiency of the wearers. Here, we report on the development and evaluation of carbon nanotube film (CNTF) and metal fiber based electric heating gloves. The electric heating elements were placed in the back of the gloves, and we tested the electric heating properties of the gloves. They showed great electrothermal performance and it had a certain repeatability and stability through multiple experiments. Then the electro-thermal and ergonomic performance of the gloves were evaluated under the severe cold outdoor environment of −20 ± 2°C. In comparison with conventional single layer polar fleece gloves and carbon fiber electric heating gloves that purchased from the market, CNTF based gloves and metal fiber-based gloves demonstrated outstanding advantages in terms of faster heating speed, great warmth retention, and enhanced finger agility, which is attributed to the electrothermal properties of CNTF and metal fiber as well as the structural design of the gloves.

Study of the structural, electronic, mechanical, electro-thermal and optical properties of double perovskite structures Cs2SbAgX6, (X = I, Br, or Cl)

In the double perovskites structures, Cs2SbAgX6, X is I, Br, or Cl, the structural, electronic, thermodynamic, thermoelectric and optical, properties have been investigated by using the density functional theory (DFT) correction method. The XRD structural study exhibits that the double perovskite structures are stable in the cubic phase structures. Elastic parameters reveal all structures to be very hard and ductile in nature. The energy band profiles display indirect band-gap of semiconductor behavior for the structures Cs2SbAgX6; X is Cl or Br, while exhibiting metallic behavior of the structure Cs2SbAgI6. The thermoelectric transport properties were verified in the temperature range (5–1000) K, which includes electrical conductivity, thermal conductivity, Seebeck coefficients, and the figure of merit, ZT, for Cs2SbAgX6 structures. These structures exhibit high thermal conductivity with good Seebeck coefficients at room temperature. The semiconducting structure, Cs2SbAgBr6, has appropriate band gaps and best Seebeck coefficients; therefore, it has the best values of ZT reached 0.000 16 at 1000 K, which means the suitable structure for employment in thermoelectric and spintronic devices applications. The optical properties of these structures exhibit that the absorption effective region at the Visible-Ultraviolet region, therefore these materials are suitable in the applications of solar cells and optoelectronic devices.

Using “intercalation bridging” to effectively improve the electrothermal properties of sheet graphite / ultrafine carbon powder conductive paste for screen printing

Using “intercalation bridging” to effectively improve the electrothermal properties of sheet graphite / ultrafine carbon powder conductive paste for screen printing

Graphene Functionalized Cotton Nonwoven for Thermotherapy

ABSTRACT Graphene-based electroconductive textile materials are advantageous over metal/gel-based heating pads for thermotherapy because of their flexibility, processability, and ability to maintain a constant temperature for an extended period. The electro-thermal properties of graphene-based nonwoven depend on its surface resistivity which in turn depends on the amount of graphene oxide (GO) deposition. In this work, highly conductive, flexible, lightweight, and antibacterial graphene functionalized cotton nonwoven with excellent electro-thermal performance is reported. For this, needle punched nonwoven structure is designed and its construction variables (Fabric GSM, punch density, and depth of penetration) are optimized with the Box-Behnken response surface design to achieve maximum GO adsorption and minimum surface resistivity. The lowest surface resistivity of 727.57 Ω sq−1 is achieved at 22.18% GO add-on. The functionalized fabric shows excellent electro-thermal properties and a maximum surface temperature of 118°C is achieved at 30V DC supply. The change in surface resistivity of rGO-cotton (reduced graphene oxide coated cotton) is insignificant even after atmospheric aging for 10 weeks, 4 washings and 10 rubbings. Antibacterial activity of 97.10% is achieved toward Staphylococcus aureus bacterium.

Enhanced mechanical properties and self‐heating performance of few‐layer graphene‐poly vinylidene fluoride based nanocomposites

AbstractThe development of a lower voltage induced high‐performance self‐heating nanocomposite materials for jole‐heating applications has been an intense challenge. Here in, we report a poly vinylidene fluoride (PVDF)/few layer graphene (FLG) based high‐performance self‐heating nanocomposites fabricated via facile solution casting method. The as fabricated PVDF‐FLG nanocomposites were tested by various characterization techniques such as X‐ray diffraction, infrared spectroscopy, Raman spectroscopy, and field emission‐scanning electron microscopy. Mechanical and electrothermal properties were investigated by universal testing machine and IR thermography. Use of increasing content of FLG from 4 to 16 wt%, as an electrically and thermally conductive filler significantly enhanced the electrical conductivity, mechanical properties, and joule heating efficiency of the nanocomposites. The conductivity of PVDF‐FLG nanocomposites increased from 0.022 S/cm to 0.815 S/cm and tensile stress improved from 27.1 MPa to 48.6 MPa with increase of FLG content from 4 wt% to 16 wt% respectively. As revealed by the IR thermography results, the joule heating effect of the nanocomposites was dominated by applied voltage and FLG content of the nanocomposites. The temperature of the nanocomposite with the highest FLG content that is, PVDF‐FLG 16 exhibited significant increase in temperature from 38.6 to 155°C °C with increase of applied voltage from 4 to 16 V respectively. Therefore, these self‐heating PVDF‐FLG nanocomposites have the great potential to be used in various joule heating applications owing to their efficient heating with low‐power consumption.

The Surface Structure Origin of Carbon Fiber with Enhanced Electrothermal Properties Prepared by Modification of Graphene Coating

The Surface Structure Origin of Carbon Fiber with Enhanced Electrothermal Properties Prepared by Modification of Graphene Coating

A Skin‐Mountable Hyperthermia Patch Based on Metal Nanofiber Network with High Transparency and Low Resistivity toward Subcutaneous Tumor Treatment (Adv. Funct. Mater. 21/2022)

Skin-Mountable Hyperthermia Patch In article number 2111228, Wei Lan, Jing Wang, Cunjiang Yu, and co-workers fabricate a soft, skin-mountable, hyperthermia patch (HTP)-based unidirectional metalized silver nanofibers network that combines high transparency and excellent electrothermal properties. The HTP allows to monitor skin irritation during hyperthermia treatment of subcutaneous tumors and other medical issues.

Electrohydrodynamics Analysis of Dielectric 2D Nanofluids.

The purpose of this present study is to prepare a stable mineral-oil (MO)-based nanofluid (NF) for usage as a coolant in a transformer. Nanoparticles (NPs) such as hexagonal boron nitride (h-BN) and titanium oxide (TiO2) have superior thermal and electrical characteristics. Their dispersion into MO is likely to elevate the electrothermal properties of NFs. Therefore, different batches of NFs are prepared by uniformly dispersing the insulating h-BN and semiconducting TiO2 NP of different concentrations in MO. Bulk h-BN NP of size 1μm is exfoliated into 2D nanosheets of size 150–200 nm, subsequently enhancing the surface area of exfoliated h-BN (Eh-BN). However, from the zeta-potential analysis, NP concentration of 0.01 and 0.1 wt.% are chosen for further study. The thermal conductivity and ACBDV studies of the prepared NF are performed to investigate the cooling and insulation characteristics. The charging-dynamics study verifies the enhancement in ACBDV of the Eh-BN NF. Weibull statistical analysis is carried out to obtain the maximum probability of ACBDV failure, and it is observed that 0.01 wt.% based NF has superior cooling and insulation properties than MO and remaining batches of NFs.