文字图像和墨料FTIR图形模糊鉴别打印机型的误差分析

通过实际案例的激光打印机打印文字,鉴别打印机型和打印机墨粉类型,分析打印文字图像或墨料(粉)FTIR图形单一鉴别与联合鉴别结果之间的误差率,评估两种鉴别方式的可靠性差异。方式一,用打印文字图像字域及其等方格分区的笔画比面积相关法模糊鉴别打印机型;方式二,用墨料傅里叶变换红外光谱(FTIR)图形吸收峰波数及其一二阶导数和自卷积相关法模糊鉴别打印机墨料种类。相对上述两种方式,计算出相关系数的距离,进行误差率的模糊综合分析。结果表明,单一鉴别方式与联合鉴别方式的误差率有显著差别。

心电图纸墨料水性化

心电图纸是我厂六十年代起就批量生产的产品之一,平均年产量在100吨左右。但在生产心电图纸时,特别在生产黑基底纸时原先的工艺是使用碳黑加溶剂性胶粘剂,需使用大量的溶剂酒精,酒精的年需要量在300吨左右。近年来化工原料的价格猛涨,酒精从原来850元/吨,上涨到3400元/吨,

《格致汇编》所载石印“流质墨”初探

石版印刷是以石板为版材的印刷技术。塞纳·菲尔德发明的石版印刷术，是在具有多孔性、善吸水、质地细密，且能较长时间保留水分的石板石上，用脂肪性物质直接描绘、书写图画和文字而制成的石版上进行印刷的绘石石印术。

Fabrication and Excellent Properties of Polyvinylidene fluoride/Graphene Composite Films as Thermal Interface Materials

The growing concern about thermal conductivityand electromagnetic shielding inelectronic equipment has promoted the development of interfacial film materials.In this work,polyvinylidene fluoride(PVDF)/graphene composite films with different graphene contents were fabricated by high-energy ball milling,cold isostatic pressing,scraping and coating,successively.High-energy ball milling is beneficial to the dispersion of graphene powder,while cold isostatic pressing can greatly enhance thermal conductivity and mechanical strength by reducing the voids in the film and increasing the contact area of graphene sheets.The thermal conductivity,tensile strength and electromagnetic shielding properties of the films were carefully investigated and compared.It was demonstrated that the thermal conductivity increased from 0.19 Wm-1.K-1 for pure PVDF to 103.9 W-m-1.K-1 for the composite film with PVDF:graphene=1:3.Meanwhile the electromagnetic shielding efficiency can reach 36.55 dB.The prepared PVDF/graphene composite films exhibit outstanding overall performance and have the potential for practical applications.

Design,progress and challenges of 3D carbon-based thermally conductive networks

The advent of the 5G era has stimulated the rapid development of high power electronics with dense integration.Three-dimensional(3D)thermally conductive networks,possessing high thermal and electrical conductivities and many different structures,are regarded as key materials to improve the performance of electronic devices.We provide a critical overview of carbonbased 3D thermally conductive networks,emphasizing their preparation-structure-property relationships and their applications in different scenarios.A detailed discussion of the microscopic principles of thermal conductivity is provided,which is crucial for increasing it.This is followed by an in-depth account of the construction of 3D networks using different carbon materials,such as graphene,carbon foam,and carbon nanotubes.Techniques for the assembly of two-dimensional graphene into 3D networks and their effects on thermal conductivity are emphasized.Finally,the existing challenges and future prospects for 3D carbon-based thermally conductive networks are discussed.

Nitrogen⁃doped 3D graphene⁃carbon nanotube network for efficient lithium storage

A 3D nitrogen⁃doped graphene/multi⁃walled carbon nanotube(CS⁃GO⁃NCNT)crosslinked network mate⁃rial was successfully synthesized utilizing chitosan and melamine as carbon and nitrogen sources,concomitant with the incorporation of multi⁃wall carbon nanotubes and employing freeze drying technology.The material amalgamates the merits of 1D/2D hybrid carbon materials,wherein 1D carbon nanotubes confer robustness and expedited elec⁃tron transport pathways,while 2D graphene sheets facilitate rapid ion migration.Furthermore,the introduction of nitrogen heteroatoms serves to furnish additional active sites for lithium storage.When served as an anode material for lithium⁃ion batteries,the CS⁃GO⁃NCNT electrode delivered a reversible capacity surpassing 500 mAh·g^(-1),mark⁃edly outperforming commercial graphite anodes.Even after 300 cycles at a high current density of 1 A·g^(-1),it remained a reversible capacity of up to 268 mAh·g^(-1).

Synthesis of Cu_2O/reduced graphene oxide composites as anode materials for lithium ion batteries

A facile way was used to synthesize Cu2O/reduced graphene oxide （rGO） composites with octahedron-like morphology in aqueous solution without any surfactant. TEM images of the obtained Cu2O/rGOs reveal that the Cu2O particles and rGO distribute hierarchically and the primary Cu2O particles are encapsulated well in the graphene nanosheets. The electrochemical performance of Cu2O/rGOs is enhanced compared with bare Cu2O when they are employed as anode materials for lithium ion batteries. The Cu2O/rGO composites maintain a reversible capacity of 348.4 mA？h/g after 50 cycles at a current density of 100 mA/g. In addition, the composites retain 305.8 mA？h/g after 60 cycles at various current densities of 50, 100, 200, 400 and 800 mA/g.

Effect of WS_2 addition on electrical sliding wear behaviors of Cu-graphite-WS_2 composites

Four kinds of Cu-based composites with different mass ratios of graphite and WS2 as lubricants were fabricated by hot-pressing method. Electrical sliding wear behaviors of the composites were investigated using a block-on-ring tribometer rubbing against Cu-5%Ag alloy ring. The results demonstrated that 800 ~C was the optimum sintering temperature for Cu-graphite-WS2 dual-lubricant composites to obtain the best comprehensive properties of mechanical strength and lubrication performance. Contact voltage drops of the Cu-based composites increased with increasing the mass ratio of WS2 to graphite. The Cu-based composite with 20% graphite and 10% WS2 showed the best wear resistance due to the excellent synergetic lubricating effect of graphite and WS2. The reasonable addition of WS2 into the Cu-graphite composite can remarkably improve the wear resistance without much rise of electrical energy loss which provides a novel principle of designing suitable sliding electrical contact materials for industrial applications.

Preparation of uniform flower-like CuO and flower-like CuO/graphene composite and their application in lithium ion batteries

Flower-like CuO and flower-like CuO/graphene composite were prepared successfully by hydrothermal method. They were characterized by X-ray diffraction, scanning electron microscopy, nitrogen adsorption, temperature-programmed reduction, and thermogravimetric analysis. It is found that the flower-like CuO microspheres, which are composed of CuO nanosheets, possess an average diameter of 4.2 μm and a Brunauer–Emmett–Teller surface area of 12.6 m2/g. Compared with the flower-like CuO, the obtained flower-like CuO/graphene composite shows an enhanced electrochemical performance with a higher capacity of 603 mA-h/g at 0.1 C rate and 382 mA-h/g at 1 C rate, and exhibits a better cycle stability with a high capacity retention of 95.5 % after 50 cycles even though at 1 C rate.

Three-dimensional MoS_2/reduced graphene oxide aerogel as a macroscopic visible-light photocatalyst

Photocatalysis is regarded as an ideal technology for solving the urgent environmental and energy issues that we face today.Among the reported photocatalysts,molybdenum disulfide（MoS2） is very promising for applications in hydrogen production and pollutant photodegradation.However,its lack of active sites and the difficulty of recovering catalysts in powder form have hindered its wide application.Here,we report the successful preparation of a macroscopic visible-light responsive MoS2/reduced graphene oxide（MoS2/RGO） aerogel.The obtained MoS2/RGO aerogel exhibits enhanced photocatalytic activity towards hydrogen production and photoreduction of Cr（Ⅵ） in comparison with the MoS2 powder.In addition,the low density（56.1 mg/cm^3） of the MoS2/RGO aerogel enables it to be used as an efficient adsorption material for organic pollutants.Our results demonstrate that this very promising multifunctional aerogel has potential applications in environmental remediation and clean energy production.

Magnetic and microwave absorbing properties of M-type barium ferrite/graphene oxide composite microwave absorber

In order to improve the absorbing properties of M- type barium ferrite absorbing materials, M-type barium ferrite/graphene oxide composites with different graphene oxide contents were synthesized by the sol-gel autocombustion method. X-ray diffraction （XRD）, a scanning electronic microscopy （ SEM ）, a physical properties measurement system （PPMS-9）, and a vector network analyzer were used to analyze their structure, surface morphology, magnetic and absorbing properties, respectively. The results show that the absorbing band of the composite absorbing material is widened and the absorbing strength is increased compared with the pure M-type barium ferrite. The sample with the content of doped graphene oxide of 3% has the minimum reflectivity at 10 to 18 GHz frequencies. Hence, the doped graphene oxide effectively improves the absorbing properties of M-type barium ferrite.

Sliding wear behavior of copper-based composites reinforced with graphene nanosheets and graphite

The mechanical and tribological properties of hot-pressed copper-based composites containing different amounts of graphene nanosheets（GNSs） are compared with those of copper-graphite（Gr） composites fabricated by the same method.The results show that the Cu-GNSs composites exhibit higher relative density,microhardness and bending strength compared with Cu-Gr composites with the same volume fraction of GNSs and Gr.Moreover,the friction coefficients and wear rates reduce significantly by the addition of GNSs,whereas the limited impact on reducing friction and wear is found on graphite.The abrasive and delamination wear are the dominant wear mechanisms of the composites.It is believed that the superior mechanical and tribological performances of Cu-GNSs composites are attributed to the unique strengthening effect as well as the higher lubricating efficiency of graphene nanosheets compared with those of graphite,which demonstrates that GNS is an ideal filler for copper matrix composites,acting as not only an impactful lubricant but also a favorable reinforcement.

Ultrasonic synthesis of CoO/graphene nanohybrids as high performance anode materials for lithium-ion batteries

A facile ultrasonic method was used to synthesize CoO/graphene nanohybrids by employing Co4（CO）12 as a cobalt precursor. The nanohybrids were characterized by SEM, TEM and XPS, and the results show that CoO nanoparticles （3-5 nm） distribute uniformly on the surface of graphene. The CoO/graphene nanohybrids display high performance as an anode material for lithium-ion battery, such as high reversible lithium storage capacity （650 mA-h/g after 50 cycles, almost twice that of commercial graphite anode）, high coulombic efficiency （over 95%） and excellent cycling stability. The extraordinary performance arises from the structure of the nanohybrids： the nanosized CoO particles with high dispersity on conductive graphene substrates are beneficial for lithium-ion insertion/extraction, shortening diffusion length for lithium ions and improving conductivity, thus the lithium storage performance was improved.

Tribological behaviors of Ag-graphite composites reinforced with spherical graphite

Two kinds of Ag-graphite composites reinforced with spherical graphite(SG)and conventional flake graphite(FG)were prepared by powder metallurgy technology.The effect of graphite morphology on the tribological behavior for the Ag-SG and Ag-FG under the dry sliding wear was investigated with a pin-on-disk tribometer at a load of 3.0 N in atmosphere condition.The results indicated that the minimum wear rate of 3.5×10^-5 mm^3/(N·m)for Ag-FG was achieved and it reduced by nearly an order of magnitude,reaching 1.6×10^-6 mm^3/(N·m)for the Ag-SG.The obviously different tribological behaviors between the Ag-SG and Ag-FG were closely related to the formation of cracks in the sub-surface.The stress concentration tended to generate at the edges of flake graphite during sliding process,which resulted in the cracks and severe delamination wear of Ag-FG.However,no cracks were found around the spherical graphite in Ag-SG.The spherical graphite can effectively inhibit the initiation and propagation of cracks,achieving high wear resistance.

Microstructure and mechanical properties of ADC12 composites reinforced with graphene nanoplates prepared by ultrasonic assisted casting

Microstructure and mechanical properties of ADC12 composites reinforced with graphene nanoplates(GNPs)prepared by high-intensity ultrasonic assisted casting were investigated.The results indicated that high-intensity ultrasound can promote the uniform distribution of GNPs in the melt,resulting in refining theα(Al)phase and Si phase.The optimal addition of GNPs was 0.9 wt.%,and the optimal ultrasonic time was 12 min.The tensile strength,the yield strength and the hardness of the composite produced under the optimal parameters were 256.8 MPa,210.6 MPa and HV 126.0,respectively,which increased by 30.5%,42.7%,and 34.8%compared with those of the matrix,respectively.After adding the GNPs,the fracture mechanism gradually turned from a brittle fracture to a ductile fracture.The good interface and distribution allowed GNPs to play the role in fine grain strengthening,dislocation strengthening and load transfer strengthening effectively.

Improvement of oxidation resistance in graphite for MgO-C refractory through surface modification

Graphite, used as a carbon source in a conventional magnesia-carbon(MgO-C) refractory, was modified with an acid reagent, resulting in a negative charge on the surface of graphite, to enhance the coating efficiency of aluminum(Al) phase, which was compared to the pristine graphite through its dispersibity and oxidation behavior. The graphite particles with and without surface modification were added, respecticely, in an Al(NO3)3 suspension used as a coating reagent, and then filtered at room temperature. The modified graphite shows better disperbility than the pristine graphite, indicating that the coating efficiency of Al precursor is enhanced in the modified graphite. With respect to oxidation behavior, the modified graphite without the coating layer is totally reacted with oxygen at heat treatment of 900 °C in air. However, the Al-coated graphite starts to react with oxygen at heat treatment of 900 °C and fully reacted with oxygen at heat treatment of 1000 °C, showing the gray and white colors, respectively. It is verified that the Al layer is individually and uniformly formed on the surface of graphite and the oxidation resistance of graphite is enhanced owing to the increased coating efficiency of Al precursor.

Preparation and properties of graphene nanoplatelets reinforced aluminum composites

5.0 vol.% graphene nanoplatelets(GNPs) and aluminum powders were mixed to prepare GNPs/Al composites via high-energy ball milling(HEBM). The mixed powders were subjected to spark plasma sintering(SPS) and subsequent hot extrusion. The microstructure and mechanical properties of extruded composites were investigated by X-ray photoelectron spectroscopy(XPS), transmission electron microscopy(TEM) and tensile tests. In the extruded composites, 5.0 vol.% GNPs were dispersed homogeneously and no serious GNP-Al interfacial reaction occurred. As a result, the yield strength and ultimate tensile strength of the extruded GNPs/Al composites reached 462 and 479 MPa, which were 62% and 60% higher than those of the extruded Al matrix, respectively. The enhanced mechanical properties were attributed to the effective load transfer capacity of dispersed GNPs. This demonstrated that it may be promising to introduce dispersed high-content GNPs via HEBM, SPS and hot extrusion techniques and GNP-Al interfacial reaction can be controlled.

EBSD characterization of Al7075/graphene nanoplates/carbon nanotubes composites processed through post-deformation annealing

The effects of the post-deformation annealing on the microstructural evolution of hot rolled Al7075 matrix composites reinforced with CNTs and GNPs were investigated.The multi-pass hot rolling was applied on the stir cast samples.Annealing was then applied to the composites at 450℃ for 4 h.Microstructural evolution was examined by SEM,EDS,and EBSD techniques.EBSD data showed that the addition of 0.87 vol.%(GNPs+CNTs)significantly inhibited the occurrence of recrystallization.Also,in the composite with 0.96 vol.%CNTs,recrystallization was partially inhibited.Whereas,in composites with 0.92 vol.%of GNPs,the occurrence of recrystallization through particle stimulated nucleation(PSN)mechanism was significantly accelerated.The volume fraction of recrystallized grains depends significantly on the occurrence of PSN in the presence of reinforcements.The intensity and type of the main components of the texture as well as the FCC fibers depend on the type of reinforcement.

In situ synthesis of a nickel boron oxide/graphdiyne hybrid for enhanced photo/electrocatalytic H_(2) evolution

Developing highly active catalysts for photo/electrocatalytic water splitting is an attractive strategy to produce H2 as a renewable energy source.In this study,a new nickel boron oxide/graphdiyne(NiBi/GDY)hybrid catalyst was prepared by a facile synthetic approach.Benefitting from the strong electron donating ability of graphdiyne,NiBi/GDY showed an optimized electronic structure containing lower valence nickel atoms and demonstrated improved catalytic performance.As expected,NiBi/GDY displayed a high photocatalytic H2 evolution rate of 4.54 mmol g^(-1)h^(-1),2.9 and 4.5 times higher than those of NiBi/graphene and NiBi,respectively.NiBi/GDY also displayed outstanding electrocatalytic H2 evolution activity in 1.0 M KOH solution,with a current density of 400 mA/cm^(2)at an overpotential of 478.0 mV,which is lower than that of commercial Pt/C(505.3 mV@400 mA/cm^(2)).This work demonstrates that GDY is an ideal support for the development of highly active catalysts for photo/electrocatalytic H2 evolution.

Enhanced Mg/graphene interface adhesion using intermediate MgO layers:First-principles prediction and analysis

Graphene-reinforced Mg matrix composites suffer seriously from the weak Mg/graphene interfacial bonding.In this study,a first-principles study was performed to evaluate the feasibility of improving the Mg/graphene bonding using an in-situ formed intermediate MgO layer.The calculated interface adhesion strengths suggested a relative ordering(from high to low)of Mg(0001)/MgO(11−1)>MgO(11−1)/graphene>Mg(0001)/graphene.The enhanced Mg/MgO/graphene interface bonding can be attributed to the newly formed strong ionic and covalent interactions at the Mg/MgO and the MgO/graphene interfaces,respectively,which replace the otherwise very weak van der Waals bonding between Mg and graphene.