Nanostructured Composite Materials Research Articles

Influence of mechanical activation mode on morphology and phase composition of Al-2Mg-nC nanostructured composite material

This article discusses peculiar features of formation of the structure and phase composition of powdered nanostructured aluminum matrix composite materials reinforced by graphene-like structures obtained by combined mechanical activation. The morphology of the powders has been studied and a neural network model has been developed which describes the dynamics of crystallite disintegration upon mechanical activation as a function of processing time and concentration of carbon nanostructures.

Nanostructured silicon nitride from wheat and rice husks

Nanoparticles, submicron-diameter tubes, and rods of Si3N4 were synthesized from the thermal treatment of wheat and rice husks at temperatures at and above 1300 °C in a nitrogen atmosphere. The whole pattern Rietveld analysis of the observed diffraction data from treatments at 1300 °C showed the formation of only hexagonal α-phase of Si3N4 with an R-factor of 1%, whereas samples treated at 1400 °C and above showed both α- and β-phases with an R-factor of 2%. Transmission electron microscopy showed the presence of tubes, rods, and nanoparticles of Si3N4. In a two-step process, where pure SiC was produced first from rice or wheat husk in an argon atmosphere and subsequently treated in a nitrogen atmosphere at 1450 °C, a nanostructured composite material having α- and β-phases of Si3N4 combined with cubic phase of SiC was formed. The thermodynamics of the formation of silicon nitride is discussed in terms of the solid state reaction between organic matter (silica content), which is inherently present in the wheat and rice husks, with the nitrogen from the furnace atmosphere. Nanostructures of silicon nitride formed by a single direct reaction or their composites with SiC formed in a two-step process of agricultural byproducts provide an uncomplicated sustainable synthesis route for silicon nitride used in mechanical, biotechnology, and electro-optic nanotechnology applications.

An Overview of Carbon Nanomaterials in Solid Acid Fuel Cell Electrodes

Micro- and nanometer sized carbon materials play an important role as components in low and intermediate temperature fuel cell electrodes. Vulcan carbon, active carbon, etc. have been used as catalyst substrates and electronic interconnect materials. As such, they reduce agglomeration of nanoparticulate catalyst and thus increase long-term stability. The catalyst utilization can be also increased significantly by improving the geometrical distribution of the catalyst. Recently, the drive towards ever smaller electrode structures has shifted attention towards carbon nanotubes (CNTs) and graphene. Their excellent electronic conductivity, extremely high specific surface area, and relatively good stability makes them suitable candidates as fuel cell electrode components. Both the catalyst distribution and utilization have been successfully improved, lowering costs and bringing the technology closer to market application. Importantly, numerous studies have recently shown functionalized CNTs and graphene, without precious metals, to be an effective catalyst for the oxygen reduction reaction. Especially nitrogen doped CNTs and graphene flakes show tremendous potential.1 Solid acid fuel cells based on CsH2PO4 as the solid state electrolyte operate at ca. 240°C and are currently performance limited at the cathode. Here, vulcan carbon has been mainly used as an electronic interconnect and catalyst support.2 Recently, carbon nanotubes have been employed, increasing the mass normalized activity of the Pt catalyst up to 61 S/mgPt.3,4 Here we combine the benefits of recent findings and present new fabrication routes based on spraydrying, metal-organic chemical vapor deposition to create highly active, nanostructured composite electrode materials, based on Pt decorated CNTs and graphene. In addition, we evaluate the suitability of surface functionalized carbon nanomaterials as precious metal free catalyst in solid acid fuel cell cathodes. Functionalization includes plasma treatment and electron beam irradiation under controlled atmospheres. Raman and XPS analysis is used before and after electrochemical measurements to evaluate structural and chemical changes. Data from impedance spectroscopy of symmetric electrochemical cells suggest effective electrochemical activity of CNTs and graphene in solid acid fuel cell cathodes. (1) Gong, K.; Du, F.; Xia, Z.; Durstock, M.; Dai, L. Science 2009, 323, 760. (2) Chisholm, C. R. I.; Boysen, D. A.; Papandrew, A. B.; Zecevic, S. K.; Cha, S.; Sasaki, K. A.; Varga, Á.; Giapis, K. P.; Haile, S. M. Interface Magazine 2009, 18, 53. (3) Varga, Á.; Pfohl, M.; Brunelli, N. A.; Schreier, M.; Giapis, K. P.; Haile, S. M. Physical chemistry chemical physics : PCCP 2013, 15, 15470. (4) Thoi, V. S.; Usiskin, R. E.; Haile, S. M. Chem. Sci. 2015, 6, 1570.

NANOMATERIALS OF SHS TECHNOLOGY FOR TRIBOLOGICAL APPLICATIONS: А REVIEW

The paper reviews the results of using the self-propagating high-temperature synthesis (SHS) powder technology to obtain various nanomaterials, which can be utilized for tribological purposes. Firstly, these are low-cost nanopowders of sulfides, oxides, nitrides, carbides, borides and metals, which can be used as solid lubricants and friction modifiers for liquid and semisolid lubricants. Secondly, these are solid compact nanostructured ceramic and composite materials for the production of tribological structures. This type of nanomaterials can be obtained either ex situ from SHS nanopowders by sintering or introducing into the melt or in situ in a single stage from initial powdered reagents by the methods of gasostatiс SHS technology, force SHS compaction, SHS casting, and SHS in the melt, which significantly simplifies and cheapens production of such materials. Thirdly, these are SHS materials for application of nanostructured coatings of different thickness with high wear resistance and low friction factor, such as nanostructured materials for surfacing and spraying, electro-spark alloying electrodes, multicomponent targets for magnetron sputtering and cathodes for vacuum arc evaporation, nanosized fillers for electrochemical and electroless chemical coatings.

Determining the Mechanical Characteristics of Composite Nanostructured Materials based on Recovered Silicone Rubber

This paper presents the mechanical characteristics of some nanocomposite materials based on recovered silicone rubber and different calcium carbonate nanopowders. The influence of the powders on the mechanical properties was studied by means of resistance at breakage, elongation at break and hardness.

Prospects of application of nanostructured heterophase polyfunctional composite materials in aero-engine manufacturing

The article provides a brief overview of the features and applications of developed and investigated nanostructured superhard composite materials and coatings on their basis. The research carried out makes it possible to draw a conclusion of great prospects of using nanostructured composite materials on the basis of carbides, carbonitrides and diborides of transitional and refractory metals for aerospace objects. The use of new composite structural materials is the top priority in the area of improving technical and economic parameters of gas turbine engines. These materials are superior to traditional materials by their basic physical and mechanical properties several-fold. Numerous studies in this field indicate that the greatest progress in the development of new advanced structural composite materials can be expected on the way to creating materials based on polymeric, metallic, intermetallic, and ceramic matrices. At present, there is a distinct trend towards the creation of units and assemblies of multiple-start gas turbine engines and power plants with longer life and increased durability. Research in the area of using new-generation composite materials is carried out in almost all developed countries, primarily in the United States and Japan.

Отделочные панели для создания экранированных помещений на основе наноструктурированных композиционных материалов

Отделочные панели для создания экранированных помещений на основе наноструктурированных композиционных материалов

Hybrid materials based on polyphenoxazine and copper nanoparticles

It is shown that, during the IR heating of polyphenoxazine in the presence of copper acetate monohydrate Cu(OOCCH3)2 · H2O in an inert atmosphere at a temperature of 250–450°C, the dehydration of phenyleneamine structures accompanied by the formation of conjugated bonds C=N and the reduction of Cu2+ to Cu0 by the evolving hydrogen followed by the formation of copper nanoparticles occur simultaneously. As a result, a nanostructured hybrid composite material, in which Cu nanoparticles are dispersed in the polymer matrix, is formed. The material shows thermal stability, and Cu nanoparticles have diameters of 5–40 nm.

Contact relaxation phenomena in nano-structured composite materials

Contact relaxation phenomena in nano-structured composite materials

Mechanical properties and rapid low-temperature consolidation of nanocrystalline Cu-ZrO2 composites by pulsed current activated heating

Metal-ceramic compositr can be obtained with an optimum combination of low density, high oxidation resistance, and high hardness of the ceramic and toughness of the metal. Therefore, metal matrix composites are recognized as candidates for aerospace, automotive, biomaterials, and defense applications. Despite its many attractive properties, the low fracture toughness of ZrO2 limits its wide application. One of the most obvious tactics to improve the mechanical properties has been to fabricate a nanostructured material and composite material. Nano-powders of Cu and ZrO2 were synthesized from 2CuO and Zr powders by high-energy ball milling. Nanocrystalline 2Cu-ZrO2 composite was consolidated within 5 minutes from mechanically synthesized powders of ZrO2 and 2Cu at low temperature, by a pulsed current activated sintering method. The relative density of the composite was 98.5%. The fracture toughness of 2Cu-ZrO2 composite in this study is higher than that of monolithic ZrO2, without great decrease of hardness.

Preparation of a nanostructured shape-memory composite material for biomedical applications

We have obtained nanoscale and microscopic surface tantalum layers on NiTi flat substrates and wires. The structure and composition of the samples were determined by scanning electron microscopy, Auger electron spectroscopy, and X-ray diffraction. With increasing sputtering time, the thickness of the surface layer increases nonlinearly. The transition layer ensures strong adhesion of the surface layer to the substrate.

HYBRID METAL-POLYMER NANOCOMPOSITES BASED ON POLYPHENOXAZINE AND COBALT NANOPARTICLES

It was shown for the first time, that after IR hating of polyphenoxazine in presence of cobalt(II) acetate Co(CH 3 CO 2 ) 2 ·4H 2 O in the inert atmosphere at the temperature of 450–650 °C, the growth of the polymer chain via the condensation reaction of phenoxazine olygomers happens simultaneously with the dehydrogenation of phenyleneamine structures with the formation of conjugated C=N bonds. Hydrogen emitted during these processes contributes to the reduction of Co 2+ to Co 0 . As a result the nanostructured composite material in which Co nanoparticles are dispersed into the polymer matrix is formed. According to TEM Co nanoparticles have size 4 < d < 14 nm. The investigation of magnetic and thermal properties of Co/polyphenoxazine nanocomposite has shown that the obtained nanomaterial is superparamagnetic and thermally stable.

Ceramic composite based on boron nitride with enhanced resistance to ion bombardment for application in hall thruster

A composition of composite nanostructured material with enhanced resistance to erosion caused by ion and electron sputtering for application in a Hall thruster is considered. A multistage process of composite production is described; full size prototypes of a final product in the form of insulation rings of accelerating channel are produced. Experimental studies on functional and mechanical properties of the obtained material are carried out. Results of analysis of the microstructure and elemental composition of the composite show prospects of its application in a Hall thruster.

Prospects of application of nanostructured heterophase polyfunctional composite materials in aero-engine manufacturing

The article provides a brief overview of the features and applications of developed and investigated nanostructured superhard composite materials and coatings on their basis. The research carried out makes it possible to draw a conclusion of great prospects of using nanostructured composite materials on the basis of carbides, carbonitrides and diborides of transitional and refractory metals for aerospace objects. The use of new composite structural materials is the top priority in the area of improving technical and economic parameters of gas turbine engines. These materials are superior to traditional materials by their basic physical and mechanical properties several-fold. Numerous studies in this field indicate that the greatest progress in the development of new advanced structural composite materials can be expected on the way to creating materials based on polymeric, metallic, intermetallic, and ceramic matrices. At present, there is a distinct trend towards the creation of units and assemblies of multiple-start gas turbine engines and power plants with longer life and increased durability. Research in the area of using new-generation composite materials is carried out in almost all developed countries, primarily in the United States and Japan.

PVC carbon nanostructure composite materials: Approaches to their fabrication and properties

The current review summarizes the literature data and our results on the application of carbon nanoparticles—nanotubes and fullerenes—as fillers in polymeric PVC composites. The technology of PVC nanocomposite production is based on the use of stearic acid and mesogenic melts as the medium of nanotubes disintegration, which makes it possible to attain homogeneous nanomodifier distribution in a polymer matrix and raise the level of technological parameters and field-performance data of PVC films. The experimental data illustrate the influence of multiwalled nanotubes and fullerenes on the processing and operating properties of PVC films.

Mechanochemical Synthesis and Fast Low-Temperature Consolidation of Nanostructured Ni-ZrO&lt;sub&gt;2&lt;/sub&gt; Composite and Its Mechanical Properties

ZrO2 has been used for hip and knee joint replacements because of the excellent combination of biocompatibility, low density and corrosion resistance. However the low fracture toughness of ZrO2 ceramic limits its wide application. One of the most obvious tactics to improve the mechanical properties has been to formulate a nanostructured composite materials. Nanopowders of Ni and ZrO2 were synthesized from NiO and Zr by high energy ball milling. A highly dense nanostructured 2Ni-ZrO2 composite was consolidated by pulsed current activated sintering within 2min under 1GPa pressure. This process allows very quick densification to near theoretical density and prohibits grain growth in nanostructured materials. The grain sizes of Ni and ZrO2 in the composite were calculated. Finally, the average hardness and fracture toughness values of nanostructured 2Ni-ZrO2 composite was investigated. [doi:10.2320/matertrans.M2014265]

Preparation of nanostructured composite ceramic materials and products under conditions of a combination of combustion and high-temperature deformation (SHS extrusion)

The results of studies showing the possibility of obtaining long products from composite ceramic nanomaterials by self-propagating high-temperature synthesis (SHS) extrusion have been presented, combining the combustion process of the initial components of the exothermic mixture and the high-temperature deformation of the combustion products. It is found that the production of nanoscale elements of the structure of the material is regulated by regime parameters of the technological process and a special choice of the initial composition of the initial exothermic mixture. The experimental results of studies of the microstructure and properties of the resulting nanostructured composite are discussed. The regularities of the influence of shear plastic deformation during the SHS extrusion on the microstructure and the size of the structural components of the synthesized ceramic composite have been studied in comparison with other methods: SHS without the application of external forces, free SHS compression, free SHS compression followed by quenching, and SHS pressing.

Non-covalent interactions and supercapacitance of pseudo-capacitive composite electrode materials (MWCNT[sbnd]COOH/MnO2/PANI)

We present the in situ oxidative synthesis and electrochemistry of novel pseudo-capacitive nanostructured composite electrode material based on multi-walled carbon nanotube (MWCNT), manganese dioxide (MnO2) and polyaniline (PANI), namely, MWCNTCOOH/MnO2/PANI (PCNAM) for high performance supercapacitor applications. The composite shows about six-fold improvement of electrochemical response compared to MWCNT. The maximum specific capacitance, energy density, and power density of PCNAM were 517.13±15.25F/g, 71.88±2.12Wh/kg and 10.08±0.26kW/kg, respectively. The high capacitance of the composite is due to the combination of the electrical double layer capacitance of MWCNT (in MWCNTCOOH) and the gradual introduction of pseudo-capacitance through the redox processes of PANI, COOH (in MWCNTCOOH) and MnO2. We have also demonstrated the charge transfer phenomena through non-covalent supramolecular interactions (i.e., π–π, n–π, and metal–π) between the components of PANI, MWCNTCOOH, and MnO2 due to the presence of double bonds, availability of lone pair electrons, free charges on nitrogen/oxygen atoms, and vacant metal d orbitals. The existence of such non-covalent interaction was supported by data from Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis.

The effect of graphene reinforcement on the mechanical properties of Al2O3 ceramics rapidly sintered by high-frequency induction heating

Despite of many attractive properties, the low fracture toughness of Al2O3 ceramic limits its wide application. One of the most obvious tactics to improve the mechanical properties has been to add a reinforcing agent to formulate a nanostructured composite material. In this respect, graphene was evaluated as the reinforcing agent of Al2O3 ceramics using high-frequency induction heated sintering (HFIHS). Highly dense alumina–graphene composites with a relative density of up to 99.6% were obtained within 2min by HFIHS under a pressure of 80MPa. The rapid consolidation method allowed the retainment of the nano-scale microstructure by inhibiting the grain growth. The grain size of alumina was reduced significantly by the addition of graphene. The addition of graphene to Al2O3 simultaneously improved the fracture toughness and hardness of alumina–graphene composite.

Synthesis of novel nanostructured composite cathode materials for lithium-ion batteries using mechanical activation

Synthesis of novel nanostructured composite cathode materials for lithium-ion batteries using mechanical activation