Synthesis and thermal transport properties of high-surface area hexagonal boron nitride foam structures

Jia, Qianru; Shi, Li

doi:10.1016/j.ijheatmasstransfer.2020.120268

Cited by 13 publications

(5 citation statements)

References 42 publications

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“…In addition, for these high-porosity foams with large κ s =κ e,wÀa , this empirical model can be reduced analytically to a parallel resistance model, κ e % ð1 À ϕ g Þκ e,wÀa þ aϕ g κ s , which has been numerically shown to be an accurate description of thermal transport in high-porosity hexagonal boron nitride (h-BN)-PMMA composite foams. [33] Here, the κ s values extracted from the parallel model differ from that extracted from the mixed parallel-series model within 5%, the latter of which is shown in Figure 4 in comparison to the reported values for UGF [12] and CNT-GF. [13] For GFs, growth at 1050 C for 3 hrs yields the highest κ s up to 770 AE 90 W m À1 K À1 , which is comparable to those reported for the UGF and CNT-GF samples.…”

Section: Thermal Transport Measurements and Resultsmentioning

confidence: 54%

“…In addition, high temperature annealing has often been used to reduce the defect concentration in graphitic materials. [38] Based on prior reports, [18,33] however, the crystallinity decreases with increased thickness of CVD graphite and h-BN layers. Therefore, the highest I D /I G ratio and lowest κ s values found in the samples grown at 1050 C with CH 4 for 15 h can be attributed to the increased graphite strut wall thickness with the increased growth time and growth temperature.…”

Section: Thermal Transport Measurements and Resultsmentioning

confidence: 86%

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Structural and Synthetic Modification of Graphitic Foams and Dendritic Graphitic Foams for Thermal Management

Jia

Liu

Fan

et al. 2021

Physica Status Solidi (a)

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Porous graphitic foam structures have been explored for applications ranging from electrochemical energy storage devices, [1][2][3][4] packaging and thermal interface materials, [5] reinforced polymer composites, [6] and flexible electronics. [7,8] Because of the high basal-plane thermal conductivity of graphite, porous graphitic foams have been used for thermal management, [9,10] such as providing an interconnected open cellular network to transfer heat from low-thermal conductivity phase change materials (PCMs) filled in the pore space for thermal energy storage. [11][12][13] By overcoming the high interface thermal resistance problem that limits the effective thermal conductivity ðκ e Þ of van der Waals networks of graphitic nanostructures, [11] the 3D continuous porous foam structures achieve considerably higher κ e than the van der Waals networks. Compared with highdensity carbon foams grown by other methods, [14][15][16][17] relatively low-density graphitic foam (GF) grown by chemical vapor deposition (CVD) on reticular nickel (Ni) foam templates is suitable for applications such as PCM thermal energy storage, where the graphite volume fraction (ϕ g ) needs to be controlled to provide both sufficient thermal transport enhancement and only a small reduction of the volume fraction of the energy-storing PCM.However, the thermal performance enhancement by CVD GF grown on reticular Ni foam is limited due to the relatively large pore size, which results in a large distance and resistance for heat flow from the functional materials inside the pore space to the high-thermal conductivity graphitic matrix grown on the sacrificial catalyst template. The low specific surface area associated with the large pores also limits the ϕ g and κ e . If the pore size can be reduced without altering the struct thickness and solid thermal conductivity (κ s ) of the graphite struts, the κ e of the GF is expected to increase together with an increase of the ϕ g . One approach to reducing the pore size is to use sintered Ni powder bed or Ni powder sintered in reticular Ni foam to replace the reticular Ni foam as the catalyst for CVD growth of powder-derived graphite foam (PGF) and hybrid GF-PGF (HGF) structures, respectively. [18] In another approach, carbon nanotubes (CNTs) have been grown on the strut walls of GF to fill the pore space and increase the specific surface area. [13,19] The κ e of these hybrid CNT-GF structures with ϕ g increased to 1.8% is about 2.4 times the value reported for GF with ϕ g of 0.45%. Although the obtained κ e of CNT-GF is still lower than PGF with ϕ g as high as 8%, the high specific surface provided by the additional CNTs yielded enhanced thermal performance, such as improved interfacial thermal transport and additional heterogeneous nucleation sites to suppress subcooling of composite PCMs for thermal energy storage. [13] However, the CNT-GF growth process requires two-step CVD reactions: one for GF growth on the reticular Ni foam template and the other for CNT growth with iron catalyst deposited on ...

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Section: Thermal Transport Measurements and Resultsmentioning

confidence: 54%

Section: Thermal Transport Measurements and Resultsmentioning

confidence: 86%

Structural and Synthetic Modification of Graphitic Foams and Dendritic Graphitic Foams for Thermal Management

Jia

Liu

Fan

et al. 2021

Physica Status Solidi (a)

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“…In addition, BN-based foams fabricated via chemical vapor deposition (CVD) (k = 0.34 W/(m•K)) and self-assembly (k = 0.18 W/(m•K)) have been reported in the literature. 45,46 However, these methods are highly complex, require high processing energy input, and have limited microstructure control. Finally, it is important to note that studies that investigate the thermal, mechanical, and dielectric properties of BN-based foam-polymer composites have been reported in the literature.…”

Section: ■ Introductionmentioning

confidence: 99%

“…As a result, thermal and mechanical property control is impossible with this template-based approach. In addition, BN-based foams fabricated via chemical vapor deposition (CVD) ( k = 0.34 W/(m·K)) and self-assembly ( k = 0.18 W/(m·K)) have been reported in the literature. , However, these methods are highly complex, require high processing energy input, and have limited microstructure control.…”

Section: Introductionmentioning

confidence: 99%

Orientation-Dependent Thermal and Mechanical Properties of 2D Boron Nitride Nanoplatelet Foams via Freeze-Drying

Orikasa,

Dolmetsch,

Lou

et al. 2023

ACS Appl. Nano Mater.

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Anisotropic two-dimensional (2D) materials, such as boron nitride nanoplatelets (BNNP), are excellent polymer reinforcement candidates due to their superior and tailorable thermal and mechanical properties. A significant challenge with integrating nanosized 2D fillers in polymer matrices is their agglomeration tendency, which has detrimental effects on the nanocomposite’s properties. Freeze-drying enables the construction of free-standing 2D material networks to be used as composite nanofillers. In this study, ultralight BNNP lamellar foams (0.05 g/cm3 dense and 97% porous) were fabricated via freeze-drying. The BNNP foams presented highly anisotropic thermal and mechanical behavior due to their lamellar morphology. The thermal conductivity of the foam along its lamellar walls is 0.31 W/(m·K), (4× greater), while it is 0.08 W/(m·K) throughout the pores. The anisotropy in the thermal properties of 2D foams is modeled. The mechanical behavior of BNNP foams was studied via quasi-static and cyclic nanoindentation. The lamellar foams are stronger (10×) along the wall direction (11.3 MPa) than across the walls (1.3 MPa). Mechanical properties were modeled by using the Gibson and Ashby model for cellular materials. A protocol is established to design 2D material foams with different concentrations and particle sizes as composite nanofillers with tailorable thermal and mechanical properties for thermal management applications.

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“…Various organic compounds , and inorganic nanoparticles have been utilized for noncovalent bond modification of hBN. Moreover, researchers have employed diverse methods, including the ice-template approach, , stress-induced method, , vacuum filtration, , electrospinning, magnetic orientation, and CVD, , to construct a thermally conductive network of hBN within the polymer matrix, resulting in a significant enhancement in the TCs of composites. In our previous study, we developed a hard-template technique using poly(methyl methacrylate) (PMMA) microspheres as sacrificial materials to fabricate isotropic flexible TCP .…”

Section: Introductionmentioning

confidence: 99%

Thermally Conductive, Electrically Insulating Epoxy Pads with Three-Dimensional Polydopamine-Modified and Silver Nanoparticle-Functionalized Hexagonal Boron Nitride Networks

Liu,

Bai,

et al. 2023

ACS Appl. Polym. Mater.

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Electronic components are susceptible to failure due to overheating during operation. Consequently, there is a growing demand for thermally conductive pads (TCPs) that exhibit high thermal conductivity (TC) and electrical insulation properties in electronic packaging. In this study, we synthesized hBN* particles by modifying hexagonal boron nitride (hBN) with polydopamine (PDA). Subsequently, a hybrid thermal conduction filler of hBN*@Ag was prepared by functionalizing silver nanoparticles (AgNPs) on the hBN* surface. Using a hard-template method, a three-dimensional thermally conductive network of hBN*@Ag (3D-hBN*@Ag) is constructed, and epoxy (EP) composites with 3D-hBN*@Ag (3D-hBN*@Ag/EP) are fabricated through the vacuum impregnation method. The results indicate that PDA enhances the interfacial compatibility of hBN-EP and reduces the filler–matrix interfacial thermal resistance (ITRf–m). However, the new interface brought by PDA will increase the filler–filler interfacial thermal resistance (ITRf–f), resulting in no significant improvement of the TC of 3D-hBN*/EP compared to 3D-hBN/EP. The AgNPs sandwiched between hBN layers are essential for enhancing the TCs of 3D-hBN*@Ag/EP composites, which contribute to an increased number of contact points between hBN layers, thereby reducing the ITRf–f. Moreover, a small amount of functionalized AgNPs on hBN will not change the electrical insulation characteristics of the composites. The resulting lightweight 3D-hBN*@Ag 6.0/EP possesses a high TC of 1.381 W m–1 K–1 at 26 wt % filler content. This study presents a strategy for improving the TC limit of composites with 3D filler networks, albeit at the expense of some electrical insulation properties.

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Synthesis and thermal transport properties of high-surface area hexagonal boron nitride foam structures

Cited by 13 publications

References 42 publications

Structural and Synthetic Modification of Graphitic Foams and Dendritic Graphitic Foams for Thermal Management

Structural and Synthetic Modification of Graphitic Foams and Dendritic Graphitic Foams for Thermal Management

Orientation-Dependent Thermal and Mechanical Properties of 2D Boron Nitride Nanoplatelet Foams via Freeze-Drying

Thermally Conductive, Electrically Insulating Epoxy Pads with Three-Dimensional Polydopamine-Modified and Silver Nanoparticle-Functionalized Hexagonal Boron Nitride Networks

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