Improvement In Thermal Conductivity Research Articles

A Comprehensive Review on Thermal Conductivity and Viscosity of Nanofluids

The innovation of nanofluids, a novel working fluid, has presented the development of heat transfer properties in machining, automotive engine cooling systems, pumping power and others to optimize the overall system. Nanofluids have pulled in scientists' cogitation from various fields in designing new thermal systems for different engineering applications due to their distinctive thermophysical properties and prospective applications. Long term stability, improved thermal conductivity, and viscosity are the principal fundamental expectations in nanofluids research to achieve better heat transfer performance. In the previous couple of decades, various investigations have been completed to explore the nanofluids properties augmentation. For instance, kerosene-based oleic acid-coated Fe3O4 nanofluids showed 300% improvement of thermal conductivity, and water-based single-walled carbon nanotube revealed 320% improvement of viscosity. This paper presents a survey of recent exploration outcomes focusing on the thermal conductivity, viscosity, flow characteristics of hybrid nanofluids, including the preparation method of nanofluids utilized in different applications. Additionally, the elements that impact nanofluids' thermophysical properties, challenges of nanofluids, and fundamental outline and analysis of most recent research studies have been discussed and referenced. Finally, although the applications of nanofluid are increasing in several engineering sectors due to advanced discoveries of nanofluid, yet, requires more research focusing on the study of various sorts of nanofluids, different combinations of several types of nanoparticles, blending proportion and identifying the component which adds to the up-gradation of heat transfer to commercialize the nanofluids in practical fields.

Thermal and electrical conductivity improvement in epoxy resin with expanded graphite and silver plating

Thermal and electrical conductivity improvement in epoxy resin with expanded graphite and silver plating

Highly flame‐retardant and low toxic polybutylene succinate composites with functionalized BN@APP exfoliated by ball milling

AbstractThis article describes the preparation of nitrogen‐phosphorus‐doped boron nitride (BN@APP) as a multifunctional nanofiller for flame‐retardant and thermal conductivity in polybutylene succinate (PBS). The BN@APP was obtained by a one‐step ball milling method. The improvement of thermal conductivity effectively reduces the generation of toxic smoke during PBS combustion. After incorporating 1.0 wt% BN@APP into the PBS, the thermal conductivity of the PBS composite is increased by 62.8%. The heat and toxic smoke are reduced significantly, the heat release rate, total heat release, and total smoke rate of PBS composites were dramatically reduced by 28.2%, 23.5%, and 44.8%, respectively, compared to pure PBS. This research offers a prospective route to prepare highly flame‐retardant composites that have low‐toxicity and smoke.

Microstructure evolution and improvement of thermal conductivity in Mg–2Sn alloy induced by La addition

Rare earth elements are commonly used to improve the properties of magnesium alloys. In this paper, the effects of various La contents on the microstructure and thermal properties of Mg–2Sn alloys were investigated. Cooling curve thermal analysis technique was adopted to reveal the microstructure evolution of Mg-2Sn-xLa alloys. La addition contributed a new eutectic reaction to occur at 639 °C and the eutectic structure was determined to be LaMgSn phase. Mg12La, Mg2Sn and matrix precipitated phases may be generated in the microstructure with further increase of La content. The thermal conductivity of Mg–2Sn alloy can be effectively improved by La addition and the maximum value 149 W/(m·K) was achieved at the Sn/La atomic ratio of 1. The thermal conductivity of Mg-2Sn-2.3La alloy could further increase to 152 W/(m·K) after solution heat treatment. The addition of La reduced the amount of solute atoms and eliminated the Sn enriched region, resulted in a rapid increase in the thermal conductivity of the Mg–2Sn alloy. The spheroidization of Mg12La phase contributed to the further improvement of the thermal conductivity after solution treatment.

A comprehensive investigation and artificial neural network modeling of shape stabilized composite phase change material for solar thermal energy storage

Shape stabilized composite phase change materials (SSCPCM) are an attractive option for solar thermal energy storage applications. The objective of the present study is to understand and quantify the shape stability of a CPCM and its kinetics behavior. A Feed-Forward Backpropagation Neural Network (FFBPNN) algorithm is developed for the prediction of phase change temperature and heat flow of composite PCMs. Myristyl alcohol mixed with expanded graphite at various loadings (5%, 10%, and 15%) are used to study the shape stability of CPCM. The characterization of PCM and CPCM is done using Fourier-transform analysis, X-ray diffraction analysis, Scanning electron microscope, and Brunauer-Emmett-Teller (BET) analysis, Differential scanning calorimetry, and Thermogravimetric analysis. The thermophysical properties of PCM and CPCM are investigated using the C-Therm instrument. DSC experiments at different heating rates are performed to estimate the activation energy of the PCM and CPCM. The SSCPCM showed 11.82%, 11.70% higher activation energy than PCM as determined by Kissinger and Ozawa models. The activation energy of CPCM increases with the loading of expanded graphite. The charging and discharging time of SSCPCM is 29.8%, 23.3% lower than the PCM, respectively. The thermal conductivity of SSCPCM is 17.6 times higher than the PCM. Therefore, SSCPCM is an attractive solution to replace the conventional available PCMs, owing to no leakage problem and a considerable improvement in thermal conductivity. Artificial Neural Network (3–18–2) topology effectively predicts the phase change temperature and heat flow of shape stabilized composite PCMs with a coefficient of determination greater than 0.989, which is helpful in the design and selection of PCM for latent heat thermal energy storage systems.

Thermal Conductivity and Flexural Strength of Two-Step Hot-Pressed SiC Ceramics

Effects of two-step hot-pressing on microstructure, thermal conductivity and flexural strength of silicon carbide (SiC) ceramics were investigated. A novel combination of aluminium nitride (AlN), La2O3 and LaF3 was employed as sinter additives in this study. SiC ceramics prepared through both one-step (OS samples) and two-step (TS samples) hot-pressing method exhibited high relative densities. Compared with OS samples, the TS samples yielded finer microstructures with both higher thermal conductivities and flexural strengths. Impedance spectroscopy analysis was employed to reinforce the investigation on thermal conductivity variations in different samples. According to the analysis results, TS samples exhibited higher fitting grain and grain boundary resistances, which stood for a lower concentration of vacancies, indicating that two-step hot-pressing is more beneficial to the elimination of defects and improvement of thermal conductivity in SiC ceramics. On the other hand, TS samples were strengthened by a combined effect of finer microstructure and formation of SiC-AlN solid solution, thereby obtained higher flexural strengths. Hence, the present study suggests that two-step hot-pressing is more favorable to the improvement of both thermal conductivity and flexural strength of SiC ceramics with AlN-La2O3-LaF3 additive combinations.

Investigations on phase change materials for enhancement of thermal conductivity

Experimental work has been undertaken to improve the thermal conductivity of the phase change material (PCM), paraffin wax (PW) by adding Al2O3 and Cu particles in increased mass fractions to elevate thermal energy storage efficiency. Composite PCM of PW-Al2O3 and PW-Cu with 5%, 10%, and 15% mass fractions were prepared by sonication. Morphology of microstructures of PW and composite PCM were examined using SEM. Thermophysical properties were measured using standard testing methods. Latent heat and specific heat were recorded with differential scanning calorimeter. Thermal conductivity was tested using two slab guarded hot plate apparatus. The results showed an improvement in thermal conductivity and latent heat of the composite PCM. The enhancement ratio of thermal conductivity was 10% and 80% for PW-Al2O3 and PW-Cu composite PCM respectively at 15 wt.%.

On the mechanisms of boiling heat transfer variations in nanofluids

Systematic pool boiling experiments were performed to elucidate the mechanisms to cause the variations of the critical heat flux (CHF) and the heat transfer coefficient (HTC) in nucleate pool boiling in water-based nanofluids. TiO2, Al2O3 and SiO2 were used as the nanoparticle materials. As reported by previous investigators, the CHF was enhanced in all the cases, but the HTC was not changed for TiO2, augmented for Al2O3, and deteriorated for SiO2. Thermal conductivity (bulk liquid effect) and several properties of the nanoparticle layer formed on the heat transfer surface (surface effect) were also measured. The present experimental results suggested that (1) wicking performance and toughness of the nanoparticle layer are of importance to achieve high CHF, and (2) HTC is determined as a result of competition between the deterioration caused by the thermal-insulation effect of the nanoparticle layer and the thermal conductivity improvement caused by the nanoparticles suspended in liquid.

Measurement and the improvement of effective thermal conductivity for a metal hydride bed - a review.

Solid-state hydrogen storage based on metal hydrides is considered a promising method for hydrogen storage. However, the low inherent thermal conductivity of metal hydride powder significantly limits the hydrogenation/dehydrogenation process in the metal hydride bed. Accurate measurement and improvement of the effective thermal conductivity of a hydride bed is of great significance for design of solid-state hydrogen storage devices. This article analyzes the factors that influence the effective thermal conductivity of a metal hydride bed, and also introduces different measurement methods and improvement ways for the effective thermal conductivity of a metal hydride bed. It is an effective way to improve the thermal conductivity of metal hydride beds by hydride powder mixed with a high thermal conductivity material and compaction. Accurately measuring the influence of hydrogen pressure, temperature and hydrogen storage capacity and other factors on the effective thermal conductivity of a metal hydride bed and obtaining the numerical equation of effective thermal conductivity play an important role in guiding the optimization design of heat and mass transfer structure of metal hydride hydrogen storage devices. The transient plane source method seems to be a better measurement choice because of short test time and easy to establish a pressure-tight and temperature control test system. However, there is still a lack of testing standards for the thermal conductivity of the hydride bed, as well as suggestions for the selection of test methods, improvement ways and design of in situ test room.

Enhancing thermophysical properties of phase change material via alumina and copper nanoparticles

The usage of phase change materials (PCMs) in thermal energy storage (TES) systems has been a promising approach in recent years. An accurate estimation of their thermophysical properties is a key factor in their optimal and efficient performance in TES systems. In this study, aluminum oxide (Al2O3) and copper (Cu) nanoparticles were incorporated in paraffin wax as a PCM to enhance its thermophysical properties. The effects of the nanoparticle type, mass fraction, and its size on the specific heat, density, thermal conductivity, and TES density of the nanocomposites, were investigated. A field emission scanning electron microscope (FESEM) was used to study their morphology. The experiments were based on three factors, nanoparticle type (Al2O3 and Cu), nanoparticle mass fraction (1%, 3%, and 6%), and nanoparticle size (30, 70, and 110 nm), while pure paraffin wax was applied as the control sample. The addition of nanoparticles to paraffin has been proven to be a promising technique. The results showed that the specific heat changes of the NePCMs have not been influenced by the factors under consideration. Also, higher mass fractions and smaller sizes of nanoparticles resulted in higher densities in NePCMs. Moreover, the thermal energy storage density of NePCMs increased at higher loading and smaller size of the nanoparticles. The improvement in thermal conductivity is especially significant if the smallest nanoparticle size with mass fractions of 3% and 6% is used. An improvement in thermal conductivity of up to 72% has been achieved at a mass fraction of 6% of 30 nm copper nanoparticles. Finally, the NePCM containing 6% mass fraction and 30 nm size of the nanoparticle (A6S and C6S) were selected as optimal NePCMs.

Improvement in Thermal Conductivity of Through-Plane Aligned Graphite Flake/Silicone Modified Epoxy Resin Composites

We describe, here, our study of the thermal conductivity (TC) properties of silicone modified epoxy resin (SEP) films which were prepared by blending low molecular weight SH-023-7 silicone resin with Dow 332 epoxy resin as the matrix of composites using graphite flakes (GF) as a thermally conductive filler. The SEP/GF composites with different filler contents and SEP/vertically aligned GF (AGF) composites utilizing various magnetic field intensities were fabricated, and the TC, and thermal stability (TS) were characterized by thermal gravimetric analysis, and the morphology was observed by scanning electron microscopy (SEM). According to the experimental results, both the TC and TS increased with the increasing addition of filler. When the weight fraction of M (M = ) was 60 wt%, the TC of the composites was 1.38 W/mk, which was 5.52 times higher than that of pure SEP (0.25 W/mK). In addition, the addition of graphite also increased the decomposition temperature of the composites. The vertically aligned GFs resulted in effective, vertical, thermally conductive pathways in the SEP matrix, and the SEP/AGF composites exhibited much higher through-plane TC compared to the non-orientated SEP/GF composites. The SEP/AGF reached 5.66 W/mK, which was approximately 4.1 and approximately 23 times higher than 60 wt% SEP/GF and pure SEP, when the nano-Fe3O4 content was 0.4 g, the strength of magnetic field was 0.65 T and the added amount of M was 60 wt%. In addition, by SEM observation, when the flake graphite was found in the direction of the magnetic field orientation, the graphite formed heat conduction channels touching each other in the magnetic field direction, improving the TC. Using XRD analyses the orientation degree of the graphite in the composite showed that the graphite obviously changed its internal orientation in the composite material when subjected to the magnetic field in the SEP melt.

Experimental investigation and artificial intelligent estimation of thermal conductivity of nanofluids with different nanoparticles shapes

Determining and modelling the effective thermal conductivity of nanofluids is always a concern of investigators. The effect of nanoparticles' shape on the effective thermal conductivity of nanofluids has not been accurately correlated with other influencing factors such as temperature and nanoparticle concentration. The main purpose of this study is to reveal the effects of influencing factors on the effective thermal conductivity of nanofluids by experimental investigation and artificial intelligence (AI). We prepared the TiO2/water nanofluids with four shapes of TiO2 nanoparticles (spherical, ellipsoidal, clubbed, and sheet) and measured the effective thermal conductivities of the samples with nanoparticles concentrations from 0.5 to 4.0 vol% as a function of temperature from 20 to 60 °C. Besides, 389 experimental datasets collected from literature and 80 datasets from our experiment were used to determine the optimum structure of AI-based models. Temperature, concentrations, shape factor, and thermal conductivity of nanoparticles were selected as independent variables, and the relative thermal conductivity of nanofluids was selected as the dependent variable. Six AI-based models were examined, including four artificial neural networks of multi-layer perceptron, cascade feedforward, radial basis function, and generalized regression neural network, adaptive neuro-fuzzy inference systems, and least-squares support vector machines, and the estimating performances were compared. The experimental results showed that increasing temperature and nanoparticles concentrations led to a remarkable improvement in the relative thermal conductivity of nanofluids, attributed to the intensified Brownian motion of nanoparticles with the high temperature and the effective collision of nanoparticles with the high concentrations. Besides, nanoparticles with a large aspect ratio provided the fast pathway with seldom crossing an interparticle boundary or junction point for effective heat transfer in the nanofluids, resulting in higher relative thermal conductivity of nanofluids. Statistical analyses confirmed that the cascade feed-forward neural network with ten hidden neurons and the Levenberg–Marquardt training algorithms was the optimized AI-based model for estimating the relative thermal conductivity of nanofluids. This model estimated allover experimental data by MSE = 0.0039, RMSE = 0.0622, AARD% = 2.66%, and R2 = 0.9908.

Fabrication of silver nanoparticles/copper nanoparticles jointly decorated nitride flakes to improve the thermal conductivity of polymer composites

In this research project, the hexagonal boron nitride@(silver/copper) (h-BN@(Ag/Cu)) hybrids are successfully synthesized through a jointly decorated two-step process in this work. First, the copper nanoparticles (CuNPs) are decorated on h-BN flakes by reducing copper ions (Cu2+). Subsequently, h-BN@(Ag/Cu) hybrids are fabricated via silver nanoparticles (AgNPs) deposition on the surface of hexagonal boron nitride@copper (h-BN@Cu) flakes. The obtained h-BN@(Ag/Cu) hybrids serve as loading fillers to substantially boost the thermal conductivity of poly(dimethylsiloxane) (PDMS). The thermal conductivity of as-prepared h-BN@(Ag/Cu)/PDMS composite reaches 1.5645 W m−1 K−1 at 25 vol% filler loading. Furthermore, the electrical properties of these composites are comprehensively investigated. Additionally, the mechanism of h-BN@(Ag/Cu) hybrids for thermal conductivity improvement are demonstrated utilizing Fogg’s model. This work may provide valuable insight and information for the design and construction of high-performance thermally conductive materials in the future.

Molecular dynamics study on the mechanism of nanofluid coolant's thermal conductivity improvement

With an increase of the heat load of internal combustion engines, the amount of heat that needs to be taken away from the cooling oil chamber is increasing. However, the thermal conductivity of existing coolants is insufficient to discharge this heat out of the internal combustion engine. Nanofluids have higher thermal conductivities than conventional fluids, so they can be considered a solution to the above problem. In this paper, different volume fractions of Cu nanoparticles are added into different coolant solutions, ethanol, ethylene glycol (EG), and propylene glycol (PG), to form alcohol nanofluids. The effect of concentration on the thermal conductivity of ethanol / EG / PG solution was analyzed by molecular dynamics method, and the thermal conductivities of the systems after adding Cu are also calculated and analyzed. It is found that the temperature gradients of the ethanol/EG/PG–water systems decrease gradually with an increase of water content, resulting in an increase of thermal conductivity. The increase of thermal conductivity is mainly due to an adsorption layer of solution atoms on the surfaces of the Cu nanoparticles. 1.5% and 3% volume fractions of Cu nanoparticles can improve the thermal conductivities of the three alcohol solutions by 12.8%, 27.3%, and 16.1%, respectively. Through an analysis of the adsorption layer on the surfaces of the Cu nanoparticles, it is found that the adsorption layer is stratified; that is, water molecules are located in the outer layer, alcohol molecules are in the inner layer, and the stratification of the adsorption layer is different in the different alcohol solutions. In the three alcohols, the delamination sites of the Cu nanoparticles are 2 nm for the ethanol system, 1.8 nm for the PG system, and 1.5 nm for the EG system. The closer the stratification position is to the nanoparticles, the better the mixture of water and alcohol molecules in the adsorption layer, and the higher the thermal conductivity. These results can provide an important reference for the application of nanofluids in internal combustion engines.

Review of Nanofluids and Their Biomedical Applications

Numerous researchers have reported significant improvements in nanofluid (NF) heat transfer (HT), suspension stability, thermal conductivity (TC), and rheological and mass transfer properties. As a result, nanofluids (NFs) play an important role in a variety of applications, including the health and biomedical engineering industries. The majority of the nanofluids (NFs) literature focuses on analyzing and comprehending the behavior of nanofluid models as heating or cooling mechanisms in various fields. This article represents a comprehensive study on nanofluids (NFs). It involves commonly used nanoparticles (NPs), magnetic nanofluids (MNFs), thermal conductivity (TC) enhancement, heat transfer (HT) enhancement, nanofluids (NFs) synthesis methods, stability evaluation methods, stability enhancement, nanofluids (NFs) applications in the biomedical field, and their impact on health and the environment. Nanofluids (NFs) play vital role in biomedical applications. It can be implemented in drug delivery systems, hyperthermia, sterilization processes, bioimaging, lubrication of orthopedic implants, and micro-pumping systems for drugs and hormones.

Constructing nanocarbon-loaded precisely phase transition-tuned energy composite eutectics with enhanced thermal conductivity: Nanocarbon’s crystallinity-dependent thermal transport

In this study, a eutectic composition consisting of myristic and stearic acid (MS) are developed to establish a cooling system with suitable operational temperature and enhanced thermal transport by adding a class of carbon nanoadditives (few-layer graphene platelets (FGP), nitrogen-doped tubular carbon (NTC) and deoxygenated graphene oxide (DGO)). Nanoadditives are added to phase transition-tuned eutectic phase change materials to derive at figure-of-merit (FOM) in enhancing thermal transport. MS-FGP exhibited significant thermal conductivity improvement as compared to MS-NTC and MS-DGO for 1 wt% loading. After ascertaining FOM, a system with variable FGP is developed, and it exhibited an increase in thermal conductivity of 128%, 420% and 597% for 1, 3 and 5 wt%, respectively. This study shed light on elucidation of underlying mechanism for nanocarbon’s structutural degree dependent thermal transport. This systematic approach could lay a step forward for controlling extreme operational temperature for thermal safety of an efficient high-powered Li-ion battery system to achieve prolonged life and energy density using phase change materials.

The effect of halloysite nanotube modification on wear behavior of carbon‐aramid fiber reinforced hybrid nanocomposites

AbstractIn this study, the carbon‐aramid fiber reinforced hybrid composites are fabricated using a vacuum‐assisted hand lay‐up method using halloysite nanotubes (HNTs) modified epoxy matrix. Ball‐on‐disk wear tests are performed to analyze the tribological effect of neat and HNTs‐added specimens at 10, 15, and 20 N loads and 1 m/s sliding speed. Additionally, the wear rate and friction coefficient results are obtained to investigate the effect of the HNTs on the tribological behavior of hybrid composites. The wear mechanism of neat and nanocomposite specimens is specified by scanning electron microscopy (SEM) images, and the elemental analysis of worn surfaces is performed using EDX. Finally, the surface morphology is evaluated with 3D topography images. Additionally, thermal camera images are used to identify the thermal conductivity effect of HNTs on wear. The wear test results show that HNTs‐addition to composite decreased the friction coefficient by 9%, 10%, and 11% for 10 N, 15 N, and 20 N loadings, respectively. The wear rate is also decreased average by 75% for wear loadings. Surface form images acquired from 3D topography support the enhancement in the friction coefficient and wear rate values. Furthermore, thermal camera images show that thermal conductivity improvement on the contact region is attributed to well thermal properties of HNTs. Furthermore, the solid‐lubricant characteristic of HNTs as forming tribofilm is determined as the main reason for the enhanced tribological performance of nanocomposites. Finally, a detailed wear mechanism is proposed to explain the wear behavior of HNTs‐added carbon‐aramid hybrid composites based on SEM images.

Thermophysical Properties of Hybrid Nanofluids and the Proposed Models: An Updated Comprehensive Study.

Thermal performance of energy conversion systems is one of the most important goals to improve the system’s efficiency. Such thermal performance is strongly dependent on the thermophysical features of the applied fluids used in energy conversion systems. Thermal conductivity, specific heat in addition to dynamic viscosity are the properties that dramatically affect heat transfer characteristics. These features of hybrid nanofluids, as promising heat transfer fluids, are influenced by different constituents, including volume fraction, size of solid parts and temperature. In this article, the mentioned features of the nanofluids with hybrid nanostructures and the proposed models for these properties are reviewed. It is concluded that the increase in the volume fraction of solids causes improvement in thermal conductivity and dynamic viscosity, while the trend of variations in the specific heat depends on the base fluid. In addition, the increase in temperature increases the thermal conductivity while it decreases the dynamic viscosity. Moreover, as stated by the reviewed works, different approaches have applicability for modeling these properties with high accuracy, while intelligent algorithms, including artificial neural networks, are able to reach a higher precision compared with the correlations. In addition to the used method, some other factors, such as the model architecture, influence the reliability and exactness of the proposed models.

Properties and performance of hybrid suspensions of MPCM/nanoparticles for LED thermal management

Mono suspensions of either nanoparticles or microencapsulated phase change material (MPCM) capsules (microcapsules) have shown superior thermophysical properties and heat transfer performance for thermal management. In this study, hybrid suspensions of nanoparticles and MPCM particles were prepared to integrate the advantages of both materials. The properties of hybrid MPCM/nanoparticle suspensions were investigated in terms of dispersion stability and thermal conductivity, and the cooling performance of the hybrid suspensions on thermal management of light-emitting diodes (LED) were studied. The experimental results show that the addition of graphene oxide, titanium dioxide (TiO2), and aluminum oxide (Al2O3) nanoparticles effectively improved the dispersion stability of the MPCM suspension (MPCMS). The thermal conductivity of the MPCMS was enhanced by the TiO2 and Al2O3 nanoparticles. The hybrid MPCM/Al2O3 suspensions, which exhibited remarkable improvement in both dispersion stability and thermal conductivity, were applied to an LED thermal management system. The results show that the cooling performance of the hybrid suspensions was enhanced compared with that of the mono suspensions of MPCM or nanoparticles. The optimal concentration of the hybrid suspension was obtained. The effects of inlet temperature of the hybrid suspensions on the cooling performance were studied.

Self-assembled supramolecule for synthesizing highly thermally conductive Cellulose/Carbon nitride nanocomposites with improved flame retardancy

The fabrication of polymer composites with excellent thermal conductivity typically involves complex matrix or fillers modifications. This study proposed a simple technique based on precursor selection for obtaining highly thermally conductive cellulose nanofiber (CNF)/supramolecule-synthesized carbon nitride (SCN) composites. Fourier-transform infrared tests demonstrated the construction of hydrogen bonds between CNF and SCN; a highly ordered structure and relatively compact in-plane stacking were confirmed via scanning electron microscopy and X-ray diffraction characterizations. Consequently, the resultant CNF/SCN composites exhibited remarkable in-plane thermal conductivity of 11.83 ± 0.41 W m−1 K−1 at 30 wt% SCN content, which was attributed to the significantly reduced interfacial phonon scattering. It also showed evident improvements in electrical insulation and flame retardancy compared with the pure CNF film, where the volume resistivity, peak heat release rate, and total heat release were remarkably enhanced by 1242% and reduced by 59.9% and 15.8%, respectively. Further analysis of char residuals revealed a relatively dense surface, high concentration of carbon materials, and a high degree of graphitization, indicating that the char residual functioned as a robust physical barrier to effectively inhibit combustion. This study provides a facile approach to achieving high-efficiency improvements in thermal conductivity and flame retardancy, and simultaneously facilitating broader applications of carbon nitride in thermal management.