Thermal Conductivity Enhancement Research Articles

Thermal Performance Optimization of Nano-Enhanced Phase Change Material-Based Heat Pipe Using Combined Artificial Neural Network and Genetic Algorithm Approach

Abstract The present study focuses on the numerical investigation of nano-enhanced phase change material (Ne-PCM)-based heat pipes designed for electronic cooling applications. It uses both paraffin wax and n-eicosane as phase change materials (PCMs) that are combined with copper oxide (CuO) nanoparticles at different concentrations of 1%, 3%, 5%, and 7%. The heat input to the heat pipe ranges from 10 to 50 W in an increment of 10 W to simulate realistic operating conditions. The idea is to predict the heat pipe's thermal performance at various combinations of nanoparticles and PCMs and compare the same to the baseline case of deionized (DI) water (without PCM). The results show a constant drop in the evaporator temperature for the Ne-PCM-assisted heat pipes. Paraffin wax and n-eicosane exhibit maximum reductions of 2.86% and 1.94%, respectively, in evaporator wall temperature compared to using conventional DI water (without PCM). The thermal resistance of the heat pipe also decreases consistently with increasing the heat input for all cases, with the most significant reduction of 33.11% and 16.63% for paraffin wax–CuO- and n-eicosane–CuO-assisted heat pipes, respectively. The maximum evaporator heat transfer coefficients recorded are 257.79 W/m2K, 353 W/m2K, and 265.18 W/m2K for heat pipes using DI water (without PCM), paraffin wax–CuO, and n-eicosane–CuO, respectively. The nanoparticles act as a thermal conductivity enhancer and bring down the heat pipe's evaporator temperature with the addition of PCMs. Thus, the effective thermal conductivity of the Ne-PCM-based heat pipe is notably higher compared to heat pipes using DI water (without PCM). To understand the complex thermal behavior of the Ne-PCM-based heat pipes and to better predict their thermal performance, a predictive model has been developed using an artificial neural network (ANN). This model drives the genetic algorithm (GA) that considers the multivariable interaction of PCMs and nanoparticle concentrations to identify the optimal configuration and results in better thermal performance of the heat pipe. Thus, the combination of ANN and GA aids a useful approach for the effective prediction of the heat pipe's thermal performance. The outcomes of this study are useful for the development of sustainable solutions in electronic cooling applications.

Preparation of liquid metal/thermoplastic polyurethane composites with enhanced thermal conductivity via rolling regulation

Abstract This work reports a method for preparing liquid metal/thermoplastic polyurethane (LM/TPU) elastic composite materials through melt blending, and enhancing the thermal conductivity of the composites using a rolling regulation process. Through observation of the microstructure of the composite material, it is found that the vane mixer can effectively disperse LM uniformly, which leads to a significant enhancement in thermal conductivity from 0.21 W m−1 K−1 of pure TPU to 2.12 W m−1 K−1 for composite with 50 vol % LM. After rolling regulation, SEM images reveal the formation of interconnected thermal conduction pathways within the composites. The thermal conductivity of the composite material with 30 vol % LM increases from 1.74 W m−1 K−1 to 2.50 W m−1 K−1, which is higher than the pre-regulation thermal conductivity of the composite with 50 vol % LM. Moreover, the thermal conductivity of the composite material with 50 vol % LM increases even further to 3.16 W m−1 K−1. The rheological behavior of the composite further substantiates the establishment of a network configuration after the rolling regulation that facilitates heat transfer. This implies that the melt blending-rolling regulation process can achieve the fabrication of composite materials with high thermal conductivity, offering a reliable strategy for industrial development of flexible thermal conductive materials.

Enhancing Thermal Conductivity of Water-Ethylene Glycol Mixtures: A Study on TiO2-Al2O3 Hybrid Nanofluids with Surfactants

This analysis examines the thermal behaviour of 40% ethylene glycol-based TiO2-Al2O3 hybrid nanofluids by synthesizing them and assessing their thermal conductivity as a function of volume concentration and temperature. These hybrid nanofluids, emerging as a promising new class of advanced operating fluids, offer remarkable potential for enhancing heat transfer performance in various thermal engineering applications. Using a two-stage synthesis method, TiO2-Al2O3/40% ethylene glycol nanofluids were prepared across five distinct volume focuses (varying from 0.02% to 0.1%), incorporating Polyvinylpyrrolidone (PVP) as a stabilizing emulsifier. Precise thermal conductivity measurements were conducted over 30 °C to 80 °C, with incremental steps of 10 °C, ensuring comprehensive data collection. The investigation yielded significant findings, notably a substantial maximum thermal conductivity enhancement of 37.44%, observed at 80 °C with a 0.1% volume concentration, demonstrating pronounced sensitivity to elevated temperatures and concentrations. The strategic addition of PVP surfactant resulted in a remarkable 125% improvement in the nanofluid's stability period, although a maximum 5.33% reduction in thermal conductivity. Considering the inadequacy of existing predictive models to capture the observed data accurately, this study proposed developing a high-precision predictive model, achieving an impressive maximum deviation of less than 3%. The research concludes that these hybrid nanofluids, characterized by their exceptional stability and significantly enhanced thermal conductivity, hold immense potential to revolutionize heat transfer applications across various domains of practical thermal engineering. This breakthrough paves the way for developing more efficient, high-performance heat transfer systems, potentially catalysing energy efficiency and thermal management advancements across diverse industrial sectors.

Investigation of enhanced PCM heat sink design under extreme thermal conditions for high-heat-generating electronic devices

In this study, a novel enhanced phase change material (PCM) heat sink design is proposed to improve energy efficiency and maintain quiet operation under extreme thermal conditions for high-heat-generating electronic devices. To overcome the thermal conductivity and heat transfer limitations of the PCM heat sinks, fins, metal foams, and nanoparticles were integrated. A simulation model for the PCM heat sink was developed based on experiments. The thermal performances of different PCM heat sinks were comprehensively evaluated and compared through an in-depth analysis of their thermal behaviors. Consequently, at the heat flux of 20 kW·m−2, a proposed nano-enhanced PCM heat sink with fins and metal foams reduces the surface temperature of high-heat-generating electronic devices by 40.0 K during pre-heating process and maintains a minimum temperature of 54.47°C, decreasing the temperature by 41.4 K during melting process compared to the PCM heat sink without thermal conductivity enhancers. Furthermore, the proposed PCM heat sink exhibited the longest critical duration, approximately 26 times longer than that of a PCM heat sink without thermal conductivity enhancers. Additionally, within the critical temperature range, employing a PCM with a suitable melting temperature and metal foam parameters is advantageous for the thermal management of high-heat-generating electronic devices.

An Ultra-Low Density and Mechanically Robust ANFs/MXene/UiO-66-NH2 Aerogel for Enhancing Thermal Conductivity and Tribological Properties of Epoxy Resins

Despite epoxy composites being used in a wide range of applications, it remains a great challenge to solve the defect of high brittleness and poor wear resistance for real engineering applications. Nanomaterials enhance fracture toughness and provide superior antifriction and wear resistance for epoxy matrix materials. In this work, a late-model ANFs/MXene/UiO-66-NH2 hybrid aerogel (AMU) with 3D layered and "mortar-brick" multi-hole structure was devised via solution impregnation and hydrothermal in situ growth processes. MXene and UiO-66-NH2 were uniformly anchored to the surface of the ANFs aerogel backbone due to hydrogen bonding forces and electrostatic adsorption. The acquired AMU-EP composites exhibited excellent thermal conductivity owing to an efficient three-dimensional network of thermal conductive pathways inside the epoxy matrix. Moreover, the efficient synergistic effect of AMU components formed a high-quality transfer film on the surface of steel balls during the friction process, which was important for enhancing the tribological properties of AMU-EP.

Modified boron nitride reinforced natural rubber composites and molecular dynamics simulation

AbstractFor thermal conductive boron nitride (BN)/polymer composites, an overabundance of BN in the formulation may significantly impair the mechanical integrity, thereby restricting their applicability in practical scenarios. In this work, we introduced a novel modifying agent, which was grafted onto the exterior of BN following high‐temperature calcination. The resultant modified boron nitride demonstrated a marked improvement in the thermal conductivity and mechanical characteristics of natural rubber (NR) composites. Upon incorporating a filler content of 60 phr, the modified boron nitride NR composite achieved tensile strength, elongation at break, and thermal conductivity to 19.34 MPa, 1402%, and 0.735 W/mK, respectively, which represented an increase of 23.97%, 75.69%, and 33.15% over the BN/NR composite. The observed enhancement in mechanical properties and thermal conductivity of the composites is the contribution of the novel modifier grafting on the BN surface, which has notably improved the interfacial interaction with NR. In addition, the binding energy, solubility parameter, free volume fraction, and radial distribution function of BN/NR and modified boron nitride NR composites were analyzed by molecular dynamics simulation, which provided support for the interface reinforcement mechanism. This simple and versatile modification method introduced in this work can broaden prospects in the design of natural rubber composites.Highlights Successful synthesized of a new modifier with long chains. Interfacial compatibility of composites explained by combining molecular dynamics simulations. Effectively improved both the mechanical and thermal conductivity of the composites. Successful use of high‐temperature assisted modification to graft modifiers onto BN surfaces.

Harnessing the potential of coal-derived graphene oxide/epoxy nanocomposites: Enhancing thermal conductivity and fracture toughness

The choice of precursor material significantly influences the properties of graphene oxide (GO), thereby providing its adaptability across diverse applications. Coal, with its distinctive molecular structure characterized by graphene-like domains and aliphatic side chains, as well as abundant impurities and heteroatoms featuring specific functional groups, emerges as a promising precursor. Employing a recently developed facile one-pot process for synthesizing semianthracite coal-derived GO (AC-GO), we have, in this study, explored its potential as a nanofiller in an epoxy matrix, resulting in AC-GO-enriched nanocomposites. The main purpose of the project was to introduce AC-GO within the epoxy matrix to enhance its thermal conductivity and fracture resistance by enhancing interfacial interactions. Our findings indicate remarkable enhancements in thermal conductivity (0.646 Wm-1K-1 at 1.0 wt% loading) and fracture toughness (6.7 MPam1/2 at 0.8 wt% loading) within AC-GO loaded nanocomposites, with these improvements being 255 % and 215 %, respectively, over those for the epoxy matrix. Remarkably, they surpass those achieved with graphite-derived GO (Gr-GO) by approximately 112 % and 76 %, respectively. Enhancing thermal conductivity and fracture toughness in epoxy nanocomposites is vital for effective heat dissipation and durability, making them ideal for high-performance electronics, aerospace, and automotive applications. These improvements can be attributed to the enhanced interactions between oxygen moieties located at the periphery of AC-GO and the fundamental epoxy-amine hardener system within the resin formulation, fostering electron acceptor–donor interactions. Furthermore, we introduce a new figure of merit (FOM) that accurately captures the combined role of thermal conductivity and fracture toughness. It is shown that this FOM can serve as a useful design tool for selecting an optimal nanofiller loading for targeted applications. The findings of our paper highlight the versatility and unique attributes of AC-GO, offering promising opportunities for applications in the industrial engineering, owing to their outstanding interfacial properties.

Thermal and Mechanical Robust Solid‐Solid Phase Change Materials Enabled by Reactive Crosslinkable Poly(Ethylene Glycol)s via Facile Thiol‐Ene Photo‐Click Chemistry

AbstractSolid–solid phase change materials (SSPCMs) are among the most promising candidates for thermal energy storage and management. Excellent shape stability, high heat storage capacity, and satisfying mechanical properties are essential for the practical applications of SSPCMs, yet giving PCMs these characteristics at the same time remains an unmet challenge. Herein, the synthesis of PEG‐PVEG copolymers is reported with various vinyl content using a synergistic catalysis strategy, leading to novel cross‐linked PEG‐based SSPCMs via a thiol‐ene photo‐crosslinking reaction. These PCMs exhibit excellent shape stability and remarkable energy storage capabilities with latent heat up to 128.3 J g−1. The materials exhibit exceptional thermal stability and retain their energy storage capacity after 500 heating‐cooling cycles. Notably, the materials show superior mechanical strength and excellent toughness. Furthermore, the latent heat enthalpy can be further improved to 146.8 J g−1 without erosion of shape stability by the encapsulation of PEG into present SSPCM. The enhancement of both thermal and electrical conductivities is also demonstrated by the phase change composites (PCCs) incorporating multi‐walled carbon nanotubes (MWCNTs). Overall, this study presents a convenient and feasible strategy for developing SSPCMs with excellent shape stability, high latent heat and satisfying mechanical properties for thermal management.

Multiscale study on the synergistic effect of interface heat transfer and filler structure on enhancing the thermal conductivity of boron nitride/alumina/polyurethane composites

The design and preparation of polymer composites for microelectronic package with high thermal conductivity is an important route to solve the thermal problem of electronic devices. The synergistic effect of interface heat transfer and hybrid filler structure on the enhancement of thermal conductivity in polyurethane composites was analyzed using a multiscale approach. Firstly, the interface heat transfer characteristics and strengthening mechanism of BN-TPU and Al2O3-TPU regulated by functionalization were analyzed by atomic scale calculation. Then, the thermal conductivity of BN/Al2O3/TPU composites under different interface thermal resistance, filler distribution, filler ratio and contents were studied through representative volume elements with interface layer structure. The results indicate that, due to the functionalized molecules increasing the phonon vibration overlap between the filler and matrix and thereby reducing the interface thermal resistance, the thermal conductivity of the composite materials shows an increasing trend with interface functionalization. Moreover, under the combined effects of constructing oriented BN structures, optimizing the ratio between BN and Al2O3, and regulating interface functionalization, the composites showed excellent thermal conductivity at low filler content. The research can provide important guidance for the preparation of highly thermal conductive polymer composites.

Nanoparticle enhanced biolubricants: a study on thermophysical properties

This paper addresses the effect of CuO nanoparticle suspension on the physical and thermal properties of Pongamia pinnata oil and 20W50 motor oil. The obtained nanolubricants with CuO nanoparticles at concentrations of 0.01%, 0.02%, and 0.05% w/v were comprehensively tested for stability, viscosity, density, thermal conductivity, and specific heat capacity. The detailed studies on zeta potential reported that the nanolubricants of 20W50 motor oil were stable at 0.02%, whereas Pongamia pinnata oil established maximum stability at 0.01%. Viscosity studies at different temperatures revealed that viscosity decreases with an increase in temperature for both oils. However, it was noted that 20W50 motor oil was more viscous compared to Pongamia pinnata oil at all temperatures. From the results, it was witnessed that the incorporation of CuO nanoparticles showed an enhancement in thermal conductivity that was marked for Pongamia oil at higher temperatures but reduced specific heat capacity in both oils. The comparative study of the thermal and physical properties of a bio-based oil, Pongamia pinnata, with that of 20W50 commercial motor oil, infused with CuO nanoparticles, has not been reported so far. The detailed properties of nanolubricants regarding the different nanoparticle concentrations studied, along with the examination of Pongamia pinnata oil as an eco-friendly alternative to conventionally used motor oil, open new possibilities for bio-based nanolubricants. Besides, the performance for specific industrial applications, especially high-load machinery and systems under moderate temperatures, brings this work under a highly relevant framework for green lubrication technologies.

Effect of temperature and nanoparticle size on the interfacial layer thickness of TiO2–water nanofluids using molecular dynamics

Abstract In the design and optimization of nanofluids, it is crucial to investigate and characterize the thermal conductivity enhancement mechanisms and their influencing factors. Although the effect of the “liquid film” on the thermal conductivity of the solid–liquid interface in nanofluids has been extensively studied, most of the research in this area has examined metal–water nanofluids or Ar-based nanofluids. In this work, non-equilibrium molecular dynamics is utilized to explore the mechanism of thermal conductivity enhancement in TiO2–water nanofluids. It is noted that a distinct interfacial layer is formed within 5 Å from the nanoparticle surface. As the nanoparticle size increases, the number density also increases, resulting in a corresponding increase in the thermal conductivity. Moreover, adding 1% TiO2 nanoparticles to water leads to an increase in thermal conductivity of 1.5–3%. Notably, the interfacial layer thickness remains relatively constant with the change in temperature. The Materials Studio analysis results indicated that the water molecule will have stable chemisorption on the titanium dioxide surface with an adsorption energy of approximately −0.96 eV. The findings of this study offer new insights and useful information to support the selection of nanomaterials for the preparation of convective systems.

Research on temperature control of smartwatch based on composite phase change material

The smartwatch is one of the most widely used wearable electronics, which combines networking, health monitoring, communication, and other multifunctional features. As it gets smaller, more integrated, and denser, its power consumption increases. Owing to its strong sealing and waterproof capabilities, the equipment has trouble dissipating the heat produced during operation, which raises the equipment's temperature. Since smartwatches come into direct contact with human skin, they can burn skin when temperatures rise beyond 45 °C. Phase change material (PCM) is suitable for thermal management of intermittent electronic devices because they absorb a large amount of heat and can maintain a constant temperature during the phase transition, which means that they absorb heat when the device is in use and release heat when it is out of use. In this study, paraffin wax (PA) is used as the phase change material, styrene ethylene butylene styrene (SEBS) is used as the flexible support material, and expanded graphite (EG) is used as the thermal conductivity enhancer to prepare PCM sheets for thermal management of smartwatches. The effects of SEBS and EG on the shape stability, enthalpy, and thermal conductivity of the composite phase change material (CPCM) with different ratios were investigated, in which PA:SEBS of 7:3 has better shape stability, so CPCM with a PA:SEBS ratio of 7:3 and different EG contents was used to make PCM sheet, which were placed in the smartwatch, and it was verified experimentally that this PCM sheet could delay the temperature rise of the case and chip of the smartwatch and prolong its usage time. This CPCM is promising for smartwatch thermal management applications.

Enhanced thermal performance of phase change mortar using multi-scale carbon-based materials

Incorporating phase change material (PCM) into construction materials is an effective method for modifying building energy regulations throughout their service life. However, the effectiveness of PCM is constrained by its low thermal conductivity, highlighting the need for efficient enhancement methods. This study introduces thermally conductive carbon-based additions at both the nano-scale and meso-scale with different shapes, including carbon nano-tube (CNT), carbon black nano-particle (CB), and carbon fibre (CF) in PCM mortar. The mixed hydrated inorganic salt serves as the core PCM, while expanded perlite acts as the supporting material for the stable PCM composite, based on the presented research. The multi-scale additions establish thermal conduction pathways that improve temperature regulation performance. The modified samples exhibited a temperature difference of 2.2 °C and a time lag of up to 20 min under natural cooling conditions. Notably, CB positively influenced thermal conductivity, while CNT demonstrated an unexpected minor reduction. The enhancement in thermal conductivity increased with the content of CB, reaching an optimal enhancement of 18 %, except at a CNT content of 0.5 %. Conversely, both CB and CNT consistently improved thermal diffusivity. Furthermore, the compressive strength of the modified samples was significantly enhanced by up to 24 % compared to PCM mortar without carbon modifications. The modification method proposed in this study significantly improves both the thermal and mechanical properties of PCM mortar.

Remarkable enhancement of thermal conductivity induced by coordination transition in SiO2 thin films

Remarkable enhancement of thermal conductivity induced by coordination transition in SiO2 thin films

Enhanced Thermal Conductivity in Poly(ether imide)-Based Composites via Constructing Microscopic Segregated Networks with Ag-Bridged Graphite Nanoplatelets

Enhanced Thermal Conductivity in Poly(ether imide)-Based Composites via Constructing Microscopic Segregated Networks with Ag-Bridged Graphite Nanoplatelets

Dependence of Thermal Conductivity on Size and Specific Surface Area for Different Based CoFe2O4 Cluster Nanofluids

Enhancing the thermal conductivity of fluids by using nanoparticles with outstanding thermophysical properties has acquired significant attention for heat-transfer applications. Nanofluids have the potential to optimize energy systems by improving heat-transfer efficiency. In this study, cobalt ferrite nanoparticles clusters with controlled mean sizes ranging from 97 to 192 nm were synthesized using a solvothermal method to develop novel nanofluids with enhanced thermal conductivity. These clusters were comprehensively characterized using transmission electron microscopy, X-ray diffraction, Raman spectroscopy, vibrating-sample magnetometry, and nitrogen physisorption. The CoFe2O4 cluster nanofluids were prepared using the two-step method with various base fluids (water, propylene glycol, and a mixture of both). Dynamic light scattering analyses of the average Z-size of the dispersed nanoadditives over time revealed that the stability of the dispersions is influenced by cluster size and the proportion of glycol in the base fluid. The thermal conductivity of the base fluid and nine different 0.5 wt% CoFe2O4 cluster nanofluids was measured using the transient hot wire method at temperatures of 293.15, 303.15, and 313.15 K, showing different temperature dependencies. The study also explores the relationships between the thermal conductivity, cluster size, and specific surface area of the nanoadditives. A maximum thermal conductivity enhancement of 4.2% was reported for the 0.5 wt% nanofluid based on propylene glycol containing 97 nm CoFe2O4 clusters. The findings suggest that the specific surface area of nanostructures is a more relevant parameter than size for describing improvements in thermal conductivity.

Influence of functionalized and non-functionalized 2D graphene nanomaterial with organic phase change materials: Thermal performance comparison

Thermal energy storage and harvesting using phase change materials (PCMs) is a crucial aspect of solar thermal utilisation and energy management. However, the intrinsic limitations associated with PCMs, such as their relatively lower thermal conductivity and sluggish thermal transport pose significant obstacles in the advancement of thermal energy harvesting and storage systems reliant on PCMs. Research explored by inclusion of nanomaterial with the PCM matrix is predominant depending on uniform diffusion and stability of the developed nanocomposite. In this research endeavour, we introduce a novel and synergistic approach to synthesis a functionalized graphene nanomaterials and compare its performance with non-functionalized graphene nanomaterial at various concentrations within organic PCMs, operating at a phase change temperature of 54 °C. The formulated nanocomposite’s thermophysical properties morphology, chemical stability, optical absorbance & transmittance, melting enthalpy, thermal stability and thermal reliability were investigated using sensitive instruments. The findings unveil a remarkable enhancement in thermal conductivity with functionalized graphene dispersed PCM exhibiting an astonishing surge of 106.7 % at a mere 0.8 wt% loading, when contrasted with conventional PCM. The optical transmittance of RT54-0.8fGr was significantly reduced from 56 % to 17.2 %, which enabled the effectiveness for solar thermal energy harnessing; meanwhile the melting enthalpy was energised to 193.4 J/g from 182.6 J/g. The developed nanocomposite with better optical property and melting enthalpy were tested for 500 numbers of accelerated thermal cycles and its chemical stability and thermal property were compared with PCM. Furthermore, a heat transfer analysis is numerically simulated to exhibit the thermal conductance performance of functionalized nanocomposite PCM over base PCM. The findings suggest that the functionalized graphene dispersed PCM matrix to exhibit highly favourable attributes for renewable thermal energy storage due to their exceptional comprehensive features.

Evaluating the energy and economic performance of hybrid photovoltaic thermal system integrated with multiwalled carbon nanotubes enhanced phase change material

Photovoltaic thermal (PVT) systems represent an advanced evolution of traditional photovoltaic (PV) modules designed to generate electrical and thermal energy simultaneously. However, achieving optimal and commercially viable performance from these systems remains challenging. To overcome this issue, in this research, multiwalled carbon nanotube (MWCNT) enhanced phase change materials (PCMs) integrated with PVT system to enhance electrical and thermal performance has been studied. An experimental investigation with three different configurations, PVT, PCM integrated PVT (PVTPCM), and MWCNT enhanced PCM integrated PVT (PVTNePCM) systems, was carried out under varying solar radiations and a water flow rate of 0.013–0.016 kg/s compared to conventional PV system. A two-step technique was employed to formulate the nanocomposites, and the energy performance of both PV and PVT systems assessed experimentally. The performance of PVTPCM and PVTNePCM systems was evaluated using the TRNSYS simulation technique. The formulated nanocomposite exhibited a 71.43% enhancement in thermal conductivity, a significant reduction in transmittance up to 92% and remained chemically and thermally stable. Integration of NePCM in the PVT system resulted in a notable decrease in panel temperature and a 25.03% increase in electrical efficiency compared to the conventional PV system. The highest performance ratio and overall efficiency for PVTNePCM were 0.55 and 81.62%, respectively, at a flow rate of 0.013 kg/s. The energy payback periods of PVTNePCM, PVTPCM, and PVT setup were 4.7, 4.8 and 5.6 years, respectively. Additionally, a significant improvement in thermal efficiency were observed for PVTPCM and PVTNePCM systems compared to water-based PVT systems, due to the energy stored in the thermal energy storage material.

Simultaneously Enhanced Thermal Conductivity and Dielectric Breakdown Strength in Micro/Nano-BN/Epoxy/PC Multilayer Composites

Simultaneously Enhanced Thermal Conductivity and Dielectric Breakdown Strength in Micro/Nano-BN/Epoxy/PC Multilayer Composites

Transferable Percolated Particle Monolayers Derived from Marangoni Flows for Thermally Conductive Dielectric Coatings.

Thermal management is becoming one of the most significant design and size limitations for high power density electronics, including motherboards, power converters, and phased array antennas for 5G communications. There are few options for conducting heat away with dielectric materials that avoid shortening or distorting the performance of these electronics. Certain highly thermally conductive 2D and 3D materials, including hexagonal boron nitride and diamond, offer ideal material properties to address these issues but are extremely challenging to process. This work studies highly oriented single-particle thick films of hexagonal boron nitride, manufactured through a modified Langmuir-Blodgett process and densified further using the Marangoni effect to attain remarkable thermal conductivity enhancement with minimal coating thickness. High loadings of hexagonal boron nitride (∼60 vol %) in dense, castable films are also produced to compare thermal spreading ability in a comparatively simpler but less-coordinated percolated system to the highly percolated particle monolayers. These procedures were applied to glass fiber reinforced polymers used in aerospace and radome applications as well as to a single-board computer to demonstrate enhanced thermal management.