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The tribological properties of the epoxy were significantly improved due to the tribological synergy of biomimetic F-CDs and sulfonated h-BN.

Thermal conductive polymer composite prepared by 3D printing technology, which has a highly vertically oriented carbon fiber structure.

A simple method was proposed to produce a flexible heat spreader with efficient thermal transportation performance.

To deal with the heat dissipation problem produced by a high integrated circuit, the preparation of heat spreaders with excellent heat transportation performance is increasing in demand. The Ti3C2 MXene sheets and copper particles were fully contacted with cellulose nanofibers by a high-speed mixer, and the composite film was prepared as a heat spreader under the action of the vacuum-assisted filtration. The MXene sheets are connected by the esterification of the carboxyl group in MXene and the hydroxyl group in cellulose nanofibers to form a chemical bond and consist of the main skeleton of the composite film. Due to the synergistic effects of MXene and copper particles, the in-plane and out-of-plane thermal conductivities of the composite film reach 24.96 and 2.46 W m−1 K−1, respectively. Compared with the pure cellulose nanofiber films, the thermal conductivity of composite films increased by 2819.2 and 187.6%, respectively. By designing two applications of composite films in the actual use process, the excellent heating conduction abilities in two directions have been proved. This measure to improve the thermal conductivities of composite films by MXene-copper binary fillers also provides ideas for the novel heat spreader.

Correction for ‘Ultrahigh thermal conductive polymer composites by the 3D printing induced vertical alignment of carbon fiber’ by Zhenbang Zhang et al., J. Mater. Chem. A, 2023, https://doi.org/10.1039/D3TA01676E.

Due to their excellent biocompatibility, outstanding mechanical properties, high strength-to-weight ratio, and good corrosion resistance, titanium (Ti) alloys are extensively used as implant materials in artificial joints. However, Ti alloys suffer from poor wear resistance, resulting in a considerably short lifetime. In this study, we demonstrate that the chemical self-assembly of novel two-dimensional (2D) diamond nanosheet coatings on Ti alloys combined with natural silk fibroin used as a novel lubricating fluid synergistically results in excellent friction and wear performance. Linear-reciprocating sliding tests verify that the coefficient of friction and the wear rate of the diamond nanosheet coating under silk fibroin lubrication are reduced by 54 and 98%, respectively, compared to those of the uncoated Ti alloy under water lubrication. The lubricating mechanism of the newly designed system was revealed by a detailed analysis of the involved microstructural and chemical changes. The outstanding tribological behavior was attributed to the establishment of artificial joint lubrication induced by the cross binding between the diamond nanosheets and silk fibroin. Additionally, excellent biocompatibility of the lubricating system was verified by cell viability, which altogether paves the way for the application of diamond coatings in artificial Ti joint implants.

Twin boundaries (TBs) are assumed to be obstacles to dislocation motion and increase the strength of metals. Here, we report the abnormal phenomenon that TBs reduce the strength of body-centered cubic (BCC) tungsten (W). [1-11]-oriented W nanowires with (121) twin planes and free of dislocations were fabricated by chemical vapor deposition. In situ tensile tests within the transmission electron microscope were performed on single-crystal and twinned W nanowires. The fracture strength of the twinned W nanowire was 13.7 GPa, 16% lower than that of the single-crystal W nanowire (16.3 GPa). The weakening mechanism of the TB was revealed by a combination of atomic-resolution characterizations and atomistic simulations. Twinned W nanowires failed by the early nucleation of a crack at the intersection of the TB with the surface. The standard strengthening mechanism by dislocation/TB interaction was not operative in W because the high Peierls barrier and stacking fault energy in W hinder dislocation nucleation and glide. These findings provide a new insight into the influence of TBs on the mechanical properties of BCC metals.

Combining the advantages of high thermal conductivities and low graphene contents to fabricate polymer composites for applications in thermal management is still a great challenge due to the high defect degree of exfoliated graphene, the poor orientation of graphene in polymer matrices, and the horrible phonon scattering between graphene/graphene and graphene/polymer interfaces. Herein, mesoplasma chemical vapor deposition (CVD) technology was successfully employed to synthesize vertically aligned graphene nanowalls (GNWs), which are covalently bonded by high-quality CVD graphene nanosheets. The unique architecture leads to an excellent thermal enhancement capacity of the GNWs, and a corresponding composite film with a matrix of polyvinylidene fluoride (PVDF) presented a high through-plane thermal conductivity of 12.8 ± 0.77 W m

For effective heat dissipation in portable electronics, there is a great demand for lightweight and flexible films with superior thermal transport properties. Despite extensive efforts, enhancing the intrinsic low thermal conductivity of polymers while simultaneously maintaining their flexibility is difficult to achieve due to the dilemma of quarrying appropriate filler loading. Herein, a cellulose nanofiber-based film with high in-plane thermal conductivity up to 72.53 W m

Bulk diamonds show great potential for optical applications such as for use in infrared (IR) windows and temperature sensors. The development of optical-grade bulk diamond synthesis techniques has facilitated its extreme applications. Here, two kinds of bulk single-crystal diamonds, a high-pressure and high-temperature (HPHT) diamond and a chemical vapor deposition (CVD) diamond, were evaluated by Raman spectroscopy and Fourier Transform Infra-Red (FTIR) spectroscopy at a range of temperatures from 80 to 1200 K. The results showed that there was no obvious difference between the HPHT diamond and the CVD diamond in terms of XRD and Raman spectroscopy at 300–1200 K. The measured nitrogen content was ~270 and ~0.89 ppm for the HPHT diamond and the CVD diamond, respectively. The moderate nitrogen impurities did not significantly affect the temperature dependence of Raman spectra for temperature-sensing applications. However, the nitrogen impurities greatly influence FTIR spectroscopy and optical transmittance. The CVD diamond showed higher transmittance, up to 71% with only a ~6% drop at temperatures as high as 873 K. This study shows that CVD bulk diamonds can be used for IR windows under harsh environments.

In order to meet the requirement of thermal performance with the rapid development of high-performance electronic devices, constructing a three-dimensional thermal transport skeleton is an effective method for enhancing the thermal conductivity of polymer composites. In this work, a three-dimensional porous diamond framework was prepared by depositing nano-crystalline diamond on alumina foam which was impregnated with epoxy to obtain a nano-crystalline diamond@alumina foam/epoxy composite. The epoxy composite with nano-crystalline diamond@alumina foam demonstrated a thermal conductivity of 2.21 W m-1 K-1, which was increased by 1063% in comparison with pure epoxy. The thermal conductivity of the epoxy composite measured under various conditions and heat transport applications demonstrates that it possesses excellent thermal transportation and stability properties. This work provides a new idea to significantly enhance the thermal transportation properties of epoxy composites in the application of advanced packaging materials.

We investigated the effects of texture shape and machining conditions on the magnitude of the texture effect of a textured diamond cutting tool in order to optimize its shape. The texture was fabricated on the surface of a diamond cutting tool by utilizing a focused ion beam and subsequent heat treatment method. Machining experiments with an aluminum alloy and nickel phosphorus (NiP) were carried out to investigate the effect of the texture shape on the machining performance. The magnitude of the texture effect changed by the machining parameters such as the cutting speed and species of work materials. These parameters affect the contact length between the tool and work materials, and the relation between the contact length and the shape of the texture is a dominant factor when determining the magnitude of the texture effect. In particular, the position of the first groove is very important in low-speed cutting. Large decreases in the cutting force and friction coefficient were obtained even for NiP. The machined surface quality was also improved by the texturing of NiP. These results indicate the effectiveness of a textured diamond cutting tool and were effective in the optimization of the texture shape.

High thermal conductivity polymer composites at low filler loading are of considerable interest because of their wide range of applications. The construction of three-dimensional (3D) interconnected networks can offer a high-efficiency increase for the thermal conductivity of polymer composites. In this work, a facile and scalable method to prepare graphene foam (GF) via sacrificial commercial polyurethane (PU) sponge templates was developed. Highly thermally conductive composites were then prepared by impregnating epoxy resin into the GF structure. An ultrahigh thermal conductivity of 8.04 W m-1 K-1 was obtained at a low graphene loading of 6.8 wt%, which corresponds to a thermal conductivity enhancement of about 4473% compared to neat epoxy. This strategy provides a facile, low-cost and scalable method to construct a 3D filler network for high-performance composites with potential to be used in advanced electronic packaging.

Thermal management materials with high thermal conductivity and good flexibility are needed for the next generation of flexible electronics. Herein, a flexible graphene/cellulose nanofiber (CNFG) composite film with high thermal conductivity was fabricated via simple vacuum-assisted filtration. The highly ordered hierarchical stacked layer structure of the graphene nanosheets endows the CNFG composite films with excellent heat-spreader performance and good flexibility. The in-plane thermal conductivity of the CNFG composite film loaded with 50 wt% graphene reached 164.7 W m−1 K−1, and the through-plane thermal conductivity reached 5.0 W m−1 K−1. More importantly, the thermal conductivities of the CNFG composite films in both the axial and radial directions barely changed after 1000 bending cycles. In addition to the good flexibility, the CNFG composite films exhibited superior mechanical properties compared to common graphene papers and neat cellulose nanofibers. The tensile strength of the CNFG composite film containing 50 wt% graphene was 72.3 ± 5.4 MPa. All these qualities make the CNFG composite films ideal heat spreaders for flexible electronic devices.

In this study, a novel method is proposed for patterning the surface of a single-crystal diamond in the sub-micrometer scale using a combination of focused ion beam (FIB) and deep ultraviolet (DUV) laser irradiations. The surface area of the diamond irradiated by the FIB was selectively machined using a low-power DUV laser, whereas the non-FIB-irradiated area was hardly machined. Hence, diamonds can be patterned at the sub-micrometer scale by selectively machining the FIB-irradiated area using lasers. To investigate the machining characteristics in this process, the effects of the FIB and DUV laser-irradiation parameters were investigated. Consequently, the shape of the DUV-irradiated area was improved by applying the gallium removal step; debris was not formed. In addition, a structure with a maximum depth of approximately 80 nm was fabricated. The damage density induced by the FIB irradiation was employed to determine the depth induced by the FIB; the depth obtained using this method is more than twice that of the heating technique in air. A concave structure was fabricated based on these results. The results indicate that the proposed method is effective for fabricating sub-micrometer-scale structures on diamond surfaces.

This paper presents the fabrication method and machining performance of a textured diamond cutting tool. To improve the machining performance, a texture was fabricated on the rake face of the diamond tool with a depth of 43 nm and width of 1.8 μm by utilizing a focused ion beam (FIB) followed by heat treatment. In addition, a FIB-induced non-diamond phase that adversely affects the machining performance was removed. A machining experiment using aluminum alloy and nickel phosphorus was conducted to evaluate the proposed method. A significant decrease in friction was observed at the tool–chip interface after texturing. This corresponds to a reduced cutting force, which indicates that the machining performance of the tool was improved by texturing. The magnitude of the effect depends on the shape and direction of the texture. The textured tool was able to machine a surface topography similar to that with a non-textured tool, which indicates that the texture effect can be obtained while maintaining the quality of the machined surface by fabricating the texture far from the cutting edge.

The nitrogen-vacancy (NV) color center in chemical vapor deposition (CVD) diamond has been widely investigated in quantum information and quantum biosensors due to its excellent photon emission stability and long spin coherence time. However, the temperature dependence of the energy level of NV color centers in diamond is different from other semiconductors with the same diamond cubic structure for the high Debye temperature and very small thermal expansion coefficient of diamond. In this work, a diamond sensor for temperature measurement with high precision was fabricated based on the investigation of the energy level shifts of NV centers by Raman and photoluminescence (PL) spectra. The results show that the intensity and linewidth of the zero-phonon line of NV centers highly depend on the environmental temperature, and the energy level shifts of NV centers in diamond follow the modified Varshni model very well, a model which is better than the traditional version. Accordingly, the NV color center shows the ability in temperature measurement with a high accuracy of up to 98%. The high dependence of NV centers on environmental temperature shows the possibility of temperature monitoring of NV center-based quantum sensors in biosystems.

The rapid increase of the packaging integration and power density of devices in electronics leads to urgent demands for high-performance thermal interface materials (TIMs) to efficiently solve the accompanying thermal management problem. Although various highly thermally conductive materials (such as graphene, carbon nanotube, and boron nitride nanosheet) combined with diversified structure design have been proposed to address this issue, it remains challenging to achieve a satisfactory TIM with both high through-plane thermal conductivity (κ⊥) and low contact thermal resistance (Rcontact) for meeting the practical application requirements. This study solves this problem by constructing a loosely packed and vertically aligned graphene monolith (VAGM), which was prepared by simply rolling up hybrid double-layer strips composed of porous polymer foam adhered onto the graphene paper, exhibiting an ultrahigh κ⊥ of 276 W m-1 K-1. Moreover, a cap modification strategy by transferring the nanometer-thick gold (Au) foils onto both sides of VAGM was carried out to further optimize the contact state with roughness surface from heater/heat sink, finally giving a low Rcontact of 0.41 K cm2 W-1 (double sides). As a result, our proposed graphene-based TIM exhibits an enhancement in cooling efficiency of ≈1.15 times compared to that of the state-of-the-art TIM (≈30 W m-1 K-1) in the TIM performance test, manifesting its superior ability to meet the ever-increasing heat dissipation requirement.

In this research, we investigated both the etching characteristics of the non-diamond phase induced by focused ion beam (FIB) irradiation and the patterning method of shallow multiple depth structures. FIB irradiation on the diamond surface induces a non-diamond phase, and this area can be selectively etched by heating in air. The dependence of the shape on the FIB and heating conditions was investigated. Process temperatures equal to or lower than 600 °C were effective for structure fabrication in terms of the fine shape of the structure. The removal depth can be controlled by varying the ion fluence and ion energy. The process temperature and heating time were important factors for determining the depth range and etch rate. The shape of the structure was affected by the morphology of the FIB-induced non-diamond phase, and the maximum etching depth was dependent on the defect density induced by FIB irradiation. Concave multiple-depth structures with depths of several tens of nanometres were fabricated based on these results, indicating the possible use of this method for shallow multiple depth patterning on diamond surfaces.

Texturing on the surface of cutting tools is an effective method to improve the friction and resultant machining performances of the tool. In this study, to fabricate nanotextures on various tools used for precision cutting, a patterning method on nanopolycrystalline diamond and cubic boron nitride tools was investigated using focused ion beam (FIB) irradiation and heat treatment. Patterning was possible using this method, and the patterning characteristics were different from those of single-crystal diamond. This method was more suitable for cutting tools compared with direct FIB machining because of its high efficiency and significantly low affected layer.

Polymeric composites with the advantages of easy process, light weight and good chemical resistance were employed in thermal management. The construction of a new type thermal conductive filler has become an efficient method for improving the thermal transportation performance of polymer composite. In this work, a barnacle-like nano-crystalline diamond@silicon carbide (ND@SiC) is prepared through depositing ND on SiC powders in a hot filament chemical vapor deposition (HFCVD). ND@SiC/PVDF composite was prepared and their thermal transportation properties were investigated. The obtained composites with 70 wt% ND@SiC loading exhibit a high thermal conductivity of 2.39 W m−1 K−1, which increased by 1132% in comparison with the pure polymer. It is also much higher than that of the composite adding 70 wt% SiC powders (1.48 W m−1 K−1). The high thermal conductivity of polymer composites by adding the ND@SiC filler is mainly attributed to the novel barnacle-like structure. This work provides a new idea to significantly enhance thermal transportation properties of composites as used in advanced packaging materials.

Polyimide (PI) composites containing one-dimensional SiC nanowires grown on two-dimensional graphene sheets (1D–2D SiCNWs-GSs) hybrid fillers were successfully prepared. The PI/SiCNWs-GSs composites synchronously exhibited high thermal conductivity and retained electrical insulation. Moreover, the heat conducting properties of PI/SiCNWs-GSs films present well reproducibility within the temperature range from 25 to 175 °C. The maximum value of thermal conductivity of PI composite is 0.577 W/mK with 7 wt% fillers loading, increased by 138% in comparison with that of the neat PI. The 1D SiC nanowires grown on the GSs surface prevent the GSs contacting with each other in the PI matrix to retain electrical insulation of PI composites. In addition, the storage modulus and Young’s modulus of PI composites are remarkably improved in comparison with that of the neat PI.

A rigid three-dimensional structure composed of silicon carbide (SiC) nanowire@graphene sheets (3DSG) was prepared using a high frequency heating process. The polyamide acid was then infused into the three-dimensional structure and imidized at 350 °C. The thermal conductivity of polyimide (PI)/3DSG composites with 11 wt% filler addition can be up to 2.63 W m−1 K−1, approximately a 10-fold enhancement when compared with the results obtained using neat PI. Furthermore, the 3DSG shows a better synergistic effect in thermal conductivity improvement, relative to a simple mixture of SiC nanowires and graphene sheets (GSs) fillers with the same additive content. The reinforced thermal properties can be attributed to the formation of efficient heat conduction pathways among GSs.

We describe a technique to improve diamond cutting tools used in nanometer- and micrometer-scale machining and formed via focused-ion-beam (FIB) micromachining. Although FIB irradiation is an effective means of fabricating arbitrary miniature shapes in diamond cutting tools, FIB irradiation induces a non-diamond phase, as well as Ga ion implantation, in the irradiated area. This adversely affects the performance of the ultra-precision machining process, especially in terms of tool life and the quality of the machined surface. To eliminate the affected layer, we applied heat-treatment techniques and investigated the optimum thermal profiles. A temperature of 500 °C applied to the cutting tool provided optimal machining of nickel phosphorus. The tool life was significantly improved, and a tool life similar to that of a non-irradiated diamond tool was obtained. The quality of the machined surface was also improved markedly owing to superior tool wear and adhesion resistance.

A focused ion beam (FIB) is an effective means of fabricating micro-to submicro-scale shapes on diamond cutting tools. However, ion irradiation of diamond tools causes ion implantation, defects, and non-diamond phases, all of which degrade the tool performance. To remove affected layers from FIB-irradiated diamond tools, heat treatment in air was applied, and the effect of the heating parameters on the etchability of the irradiated area was investigated. It was found that the affected layer could be etched and removed from the diamond tool surface, even at 500 °C. In machining experiments on aluminum alloy and nickel phosphorus, machining performance was improved by the applied heating technique, and the cutting forces and machined surfaces were similar to those obtained with the non-irradiated tool. These results indicate that the proposed heating technique is effective for diamond cutting tools shaped by FIB.

Tool shape is an important factor determining the shape and accuracy of machined areas in ultra-precision machining. Use of a focused ion beam (FIB) is an effective means to fabricate micro- to submicro-scale tool shapes. However, ion irradiation causes doping and defects in the tool that reduce tool performance. To use FIB machining on a single-crystal diamond tool without degrading tool performance, a combination of 500 °C heat treatment and aluminum deposition was used to remove gallium (Ga) ions induced by ion irradiation. The method was evaluated through machining experiments that showed that irradiation of Ga ions causes work materials to adhere to the tool surface. This adhesion and the resulting rapid tool wear were reduced by heat treatment. The proposed method also improved the transcription ability and wear resistance of the tool so it was capable of producing a surface quality better than or equal to that produced by non-irradiated tools, even over long cutting distances.

The high integration and high power devices cause serious local heat accumulation, which will damage the reliability and service life of devices. Efficient heat dissipation has become priority issues for electronic devices. As a one-dimension thermal conductive fillers, carbon fibers (CFs) exhibits ultra-high thermal conductive performance. However, the superiority is not fully utilized by traditional approaches especially for short CFs. In this work, a micro-phragmites communis structure was constructed for enhance thermal transfer property of composites. And the composites were obtained by immersed in polydimethylsiloxane (PDMS) with vacuum-assisted. Owing to vertical CFs structure, the through-plane thermal conductivity of polymer composites achieving 6.04 W m−1 K−1 at low CFs loading. Further, the surface temperature variation of composites in heating and cooling process was observed by infrared camera, and it exhibits excellent heat transfer performance. The applicability of the high thermal conductive composite was investigated by applied in CPU heat dissipation. This work reveals promising approaches for fully utilize the ultra-high axes thermal conductivity of CFs to prepared high thermal conductive composites.

In this study, we report a facile approach to fabricate epoxy composite incorporated with silicon carbide nanowires (SiC NWs). The thermal conductivity of epoxy/SiC NWs composites was thoroughly investigated. The thermal conductivity of epoxy/SiC NWs composites with 3.0 wt% filler reached 0.449 Wm−1 K−1, approximately a 106% enhancement as compared to neat epoxy. In contrast, the same mass fraction of silicon carbide micron particles (SiC MPs) incorporated into epoxy matrix showed less improvement on thermal conduction properties. This is attributed to the formation of effective heat conduction pathways among SiC NWs as well as a strong interaction between the nanowires and epoxy matrix. In addition, the thermal properties of epoxy/SiC NWs composites were also improved. These results demonstrate that we developed a novel approach to enhance the thermal conductivity of the polymer composites which meet the requirement for the rapid development of the electronic devices.