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In this study, we examined the applicability of a response surface approach in the experimental design, parametric optimization, and formulation of predictive models in the 3D printing of aluminium-7075/Ti48Zr20Hf15Al10Nb7 shape memory high-entropy alloy (SMHEA) composite. The input variables consist of the SMHEA dosage (A), laser power (B), and powder flow rate (C), which vary from 2 to 8 wt%, 400 to 800 W, and 1.44 to 7.2 g/min, respectively. In the meantime, the yield strength, tensile ductility and modulus, hardness, damping capacity, and loss modulus were examined. The ANOVA results indicated that the input variables A, B, and C had significant effects on the responses, resulting in mathematical models with a high degree of fitness that adequately represented the experimental outcomes. Optimal parametric optimization was achieved at 6.4 wt%, 388 watts, and 3.6 g/min with a desirability of 0.916%. Comparing the predicted responses to the validation results under optimal conditions revealed a deviation < ± 5%, validating the models' potency to predict the responses. Thus, optimal parametric conditions for the development of a 3D-printed aluminum-7075/Ti48Zr20Hf15Al10Nb7 composite were confirmed to be adequate. [ABSTRACT FROM AUTHOR]

At present, the electromagnetic characteristics of various materials, including polymeric materials, are being widely studied with the aim of using them as radio-absorbing coatings in electronics products. One such material is pyrolyzed polyacrylonitrile (PPAN). This article considers a model of electromagnetic wave absorption by PPAN layers with electrical conductivity of 72 and 180 S/m and a layer width of 0.15 to 2 mm, including those containing a metal filler (the so-called PPAN-based metal composite), in the frequency range of 3–50 GHz. The experimental data are compared with the data obtained in the course of simulation in terms of parameters such as the reflection, transmission, and absorption indices. Modeling is done in the software package COMSOL Multiphysics. [ABSTRACT FROM AUTHOR]

Carbon nanotube (CNT)/metal composites have attracted much attention due to their enhanced electrical and thermal performance. How to achieve the scalable fabrication of composites with efficient dispersion of CNTs to boost their performance remains a challenge for their wide realistic applications. Herein, the nanoscale dispersion of CNTs in the Stannum (Sn) matrix to boost thermal and electrical conductivity via facile ball milling techniques was demonstrated. The results revealed that CNTs were tightly attached to metal Sn, resulting in a much lower resistivity than that of bare Sn. The resistivity of Sn with 1 wt.% and 2 wt.% CNTs was 0.087 mΩ·cm and 0.056 mΩ·cm, respectively. The theoretical calculation showed that there was an electronic state near the Fermi level, suggesting its electrical conductivity had been improved to a certain extent. In addition, the thermal conductivity of Sn with 2 wt.% CNTs was 1.255 W·m−1·K−1. Moreover, Young's modulus of the composites with CNTs mass fraction of 10 wt.% had low values (0.933 MPa) under low strain conditions, indicating the composite shows good potential for various applications with different flexible requirements. The good electrical and thermal conductive CNT networks were formed in the metal matrix via facile ball milling techniques. This strategy can provide guidance for designing high-performance metal samples and holds a broad application potential in electronic packaging and other fields. [ABSTRACT FROM AUTHOR]

The morphology/microstructure and ignition/combustion properties of ball-milled Al composite powders containing Ti, Zr, and Mg were studied and compared. The particles contained 50 at% Al or Al-8Mg alloy and 50 at% Ti or Zr, yielding four different chemistries: Al:Zr, Al-8Mg:Zr, Al:Ti, and Al-8Mg:Ti. Ignition temperatures were measured by resistively heating the powders on a nichrome wire in air. All composite particles exhibit ignition temperatures (~625-725 K) that are significantly lower than those for pure Al of similar size (~2100 K). The Ti-based composites have slightly lower ignition temperatures than the Zr-based powders. The difference is attributed to the Ti-based powders having more energetic intermetallic formation reactions as measured by differential thermal analysis (DTA). The microstructures of the as-milled composites were analyzed via powder x-ray diffraction and scanning electron microscopy and helped to explain the measured heats and ignition temperatures. The addition of Mg did not significantly affect the ignition temperatures, but it did alter the number of peaks, the peak positions and overall heat release in the DTA scans compared to the binary samples. Mg also improved refinement of both internal microstructures and the size of composite particles during milling. Spectroscopy and high-speed videography of the combusting powders revealed vapor-based emission species such as Al and AlO for the binary samples and Mg and MgO for the ternary composites. Higher average maximum combustion temperatures were measured for the Ti-based powders (3470 ± 450 K and 3300 ± 880 K) than the Zr-based powders (3340 ± 350 K and 3100 ± 400 K) with the Mg containing powders being hotter for Ti and Zr chemistries. The Ti-based composites displayed a dual-phase combustion mechanism and micro-explosions, similar to those seen for Al:Zr composites in previous studies. [ABSTRACT FROM AUTHOR]

Carbon nanotube (CNT)/metal composites have attracted much attention due to their enhanced electrical and thermal performance. How to achieve the scalable fabrication of composites with efficient dispersion of CNTs to boost their performance remains a challenge for their wide realistic applications. Herein, the nanoscale dispersion of CNTs in the Stannum (Sn) matrix to boost thermal and electrical conductivity via facile ball milling techniques was demonstrated. The results revealed that CNTs were tightly attached to metal Sn, resulting in a much lower resistivity than that of bare Sn. The resistivity of Sn with 1 wt.% and 2 wt.% CNTs was 0.087 mΩ·cm and 0.056 mΩ·cm, respectively. The theoretical calculation showed that there was an electronic state near the Fermi level, suggesting its electrical conductivity had been improved to a certain extent. In addition, the thermal conductivity of Sn with 2 wt.% CNTs was 1.255 W·m−1·K−1. Moreover, Young’s modulus of the composites with CNTs mass fraction of 10 wt.% had low values (0.933 MPa) under low strain conditions, indicating the composite shows good potential for various applications with different flexible requirements. The good electrical and thermal conductive CNT networks were formed in the metal matrix via facile ball milling techniques. This strategy can provide guidance for designing high-performance metal samples and holds a broad application potential in electronic packaging and other fields.

Changes in the unique properties of cast metal, including density, crystalline structure, and mechanical strength, can be formed in the direction from the rotational center of a mold to its periphery by applying centrifugal forces on a crystallizing melt. The versatile method can be applied to a wide range of alloys for obtaining castings weighing from several grams to tens of tons. However, significant energy and material consumption determines the efficiency of its application under conditions of predominantly mass and large-batch types of production. While the centrifugal method is currently used to produce castings of rotational parts, such as pipes, rings, and various cylindrical products, the thermophysical action of a centrifugal force field on alloys is of interest not only for the production of cast billets, but also for the directed structural formation of various nature materials, including composite ones. In order to expand the range of applicability of the centrifugal process in industrial settings, this paper presents the results of an analysis of current practices for producing alloys and manufacturing cast billets. Additionally, its advantages in comparison with fixed mold casting methods and options for eliminating its disadvantages are specified along with an identification of current trends in energy and resource efficient methods for the structural formation of materials, including those obtained from secondary raw materials. The effect of centrifugal action on crystallizing melts obtained by aluminothermic remelting of thermite compositions is shown. [ABSTRACT FROM AUTHOR]

This study delves into the untapped potential of BCN (boron carbon nitride) as a photocatalyst, highlighting its remarkable porosity and bandgap adjustability. In pursuit of enhancing BCN's photocatalytic capabilities, we introduce an innovative approach to incorporate Bi 2 O 3 nanoparticles onto BCN's surface through a thermal condensation process. The assessment of photocatalytic activity involved the degradation of both non-dye and dye compounds (acetaminophen, malachite green, and reactive blue) under UV–visible light irradiation. Our findings reveal that the Bi 2 O 3 /BCN (BiBCN) composites exhibit significantly improved photocatalytic activity compared to individual BCN or Bi 2 O 3. Notably, the 5%BiBCN photocatalyst excels, achieving removal rates of 80.88 % for ACE, 98.6 % for MG, and 97.7 % for RB within 120 min under UV–Vis light exposure. Characterization unveils that the composite photocatalysts enhance the separation of photogenerated carriers, primarily attributed to the formation of heterojunctions. Our proposed mechanism underscores the synergy of increased specific surface area and the heterojunction formed by the interaction between Bi 2 O 3 and TCN in enhancing photocatalytic performance. Altogether, this study sheds light on the promising potential of BCN-based heterojunction photocatalysts for efficient water depollution. [Display omitted] [ABSTRACT FROM AUTHOR]

Cold spray is the solid-state process for elaboration of metal coatings and free-standing parts. The absence of material melting during build-up of deposit allows to apply this technology for producing metal composites with innovative properties. The cold spray metal composites could be produced by deposition of composite powders or by simultaneous spraying of powder mixtures. The second approach is considered as the most robust and the simplest one that is important for industrial application. In the present paper, the comprehensive review of the actual knowledge about the formation of metal composite by simultaneous cold spraying of several powders is performed. The main advantages of this approach as well as the issues and the limits are analyzed. The eventual applications of the cold spray composite deposits are also discussed. [ABSTRACT FROM AUTHOR]

Abstract In this work, a chemiluminescence (CL) aptasensor was designed for detection of microcystin-RR (MC-RR) by introducing Cu/Co nanorods acting as CL catalyzer. Cu/Co nanorods were firstly synthesized throughout a hydrothermal method. Then the thiolated MC-RR aptamer was immobilized on the surface of Cu/Co nanorods, which was employed for recognizing of MC-RR target. In the presence of MC-RR, the conformational change of MC-RR aptamer was happened via recognizing between MC-RR and its aptamer. The luminol CL was catalyzed by Cu/Co nanorods that influenced by conformational change of MC-RR aptamer. The formed MC-RR/aptamer composite prevented the diffusion channel of luminol substrate toward the Cu/Co nanorods surface and restrained the Cu/Co nanorods catalyzing luminol CL. And the intensity of CL depended on the concentration of MC-RR. Under optimal condition, the CL aptasensor had a linear range in 0.1 to 70 nM and a low detection limit of 3.3 × 10−11 M for MC-RR. This study provided a significant method for MC-RR detection in real samples with excellent selectivity. Highlights • Cu/Co BNMs had superior over Cu, Co monometallic nanomaterials and Co(NO 3) 2 , Cu(NO 3) 2. • Cu/Co nanorods were used as nanocatalysts and the carrier for CL detection. • LOD for Microcystin-RR 33 fM was gained. [ABSTRACT FROM AUTHOR]

A novel processing method to fabricate AlN-MgO-MgAl2O4composites has been developed, using non-sintered, porous, aluminum nitride (AlN) preforms infiltrated with a magnesium alloy in two directions, downward and upward, at relatively low temperatures (650°C, 800°C, 950°C). Microstructural, phase, and chemical analyses show that at 950°C and 135 min holding time, a continuous network of ceramic phases can be achieved successfully. Magnesium oxide and spinel phases (MgAl2O4) are formed in-situ,when nitrogen gas is used. Due to the formation of a magnesium nitride layer on the surface of the non-sintered aluminum nitride, the infiltration mechanism proceeds effectively. No metallic phases are observed in the samples processed at 800°C and higher: these samples show high electrical resistivity ranging from 6.73×108to 2.10×1011Ωcm. Thermal diffusivity, heat capacity and density have been measured using the nano-flash method, differential scanning calorimetry and Archimedes technique, respectively. The effects of residual porosity and holding time on the thermal conductivity have been studied. Maximum thermal conductivity and density at room temperature are 96 W/(mK) and 2.45 g/cm3, respectively.

A composite energy storage material (ESM) with inclusions of a low-melting point metal encapsulated in protective metal oxide shells is prepared and characterized. ESM precursor is a metal matrix composite with metal oxide inclusions. Controlled redox reaction between the matrix and inclusions yields a composite with inclusions of an oxide encapsulated, easy to melt metal. Al/Bi 2 O 3 nanocomposite thermites served as precursors for ESM with Al matrix and Bi inclusions encapsulated with Al 2 O 3 . Thermal and mechanical properties of the ESM were compared to those of reference binary Al/Bi and ternary Al/Bi/Al 2 O 3 materials. The material containing encapsulated Bi inclusions stored energy by melting and solidifying Bi inclusions repeatedly. The inclusions did not drift upon heating; composite structure remained largely intact upon thermal cycling. Conversely, the structure of reference materials with similar compositions but without encapsulated Bi inclusions was not preserved upon thermal cycling. Molten Bi tended to separate from Al and form coarse network of inclusions. Upon cycling, Bi accumulated on surface of the material. Difference in mobility between encapsulated and non-encapsulated Bi inclusions caused differences in the mechanical properties of the composites. Materials with encapsulated Bi inclusions were much stronger and capable of retaining their structure and strength despite thermal cycling. [ABSTRACT FROM AUTHOR]

Polyacrylic acid (PAA) is an important industrial chemical, which has been extensively applied in various fields, including for several biomedical purposes. In this study, we report the synthesis and modification of this polymer with various phenol imides, such as succinimide, phthalimide and 1,8-naphthalimide. The as-synthesized derivatives were used to prepare polymer metal composites by the reaction with Zn+2. These composites were characterized by using various techniques, including NMR, FT-IR, TGA, SEM and DSC. The as-prepared PAA-based composites were further evaluated for their anti-microbial properties against various pathogens, which include both Gram-positive and Gram-negative bacteria and different fungal strains. The synthesized composites have displayed considerable biocidal properties, ranging from mild to moderate activities against different strains tested. [ABSTRACT FROM AUTHOR]

Results of an experimental investigation into the deformation and destruction of a metal composite vessel with a cryogenic gas are presented. Its structure is based on basalt, carbon, and organic fibers. The vessel proved to be serviceable at cryogenic temperatures up to a burst pressure of 45 MPa, and its destruction was without fragmentation. A mathematical model adequately describing the rise of pressure in the cryogenic vessel due to the formation of a gaseous phase upon boiling of the liquefied natural gas during its storage without drainage at the initial stage is proposed. [ABSTRACT FROM AUTHOR]

In this study, the effects of reinforcement volume fractions on abrasive wear behavior were examined in Al–MgO reinforced metal matrix composites of 5%, 10% and 15% reinforcement – volume ratios produced by melt-stirring. Abrasive wear tests were carried out by 60, 80 and 100 mesh sized Al 2 O 3 abrasive papers and pin-on-disc wear test apparatus under 10, 20 and 30 N loads at 0.2 m/s sliding speed. The mechanical properties such as hardness and fracture strength were determined. Subsequent to the wear tests, the microstructures of worn surfaces were examined by scanning electron microscope analyses. While increased MgO reinforcement volume fraction in the composite resulted increased hardness, fracture strength was determined to decrease. Additionally, it was found that increased MgO reinforcement volume fraction in the composite was accompanied with increased wear loss and porosity as well as reinforcement – volume ratio was identified to be significant determinants of abrasive wear behavior. [ABSTRACT FROM AUTHOR]

Polyacrylic acid (PAA) is an important industrial chemical, which has been extensively applied in various fields, including for several biomedical purposes. In this study, we report the synthesis and modification of this polymer with various phenol imides, such as succinimide, phthalimide and 1,8-naphthalimide. The as-synthesized derivatives were used to prepare polymer metal composites by the reaction with Zn+2. These composites were characterized by using various techniques, including NMR, FT-IR, TGA, SEM and DSC. The as-prepared PAA-based composites were further evaluated for their anti-microbial properties against various pathogens, which include both Gram-positive and Gram-negative bacteria and different fungal strains. The synthesized composites have displayed considerable biocidal properties, ranging from mild to moderate activities against different strains tested.

Highlights: [•] Comprehensive review of the sensors developed for bisphenol-A. [•] Every section begins with brief explanation of sensors to improve understanding. [•] Figures explain the principles and the working mechanisms of sensors. [•] Details of the recent work are given priority and collated in the form of a table. [•] We discuss future perspectives in development of sensors for bisphenol-A. [Copyright &y& Elsevier]

An iterative model is proposed to describe the mechanical behavior of 3D-reinforced metal composite media in which materials of their components operate under the conditions of steady-state anisotropic creep. The simulation is carried out both with and without account of the inelastic dilatation of phase materials. [ABSTRACT FROM AUTHOR]

Volt-ampere characteristics of the sliding zone of steel-base metal composites in a current collection mode are presented. Friction is implemented at a current density of 100 A/cm for the cases of absence and presence of a Pb-Sn melt in the friction zone. An elementary model of rough surface contact is proposed to assess the relation between the area occupied by the melt and the current density. It is shown that the addition of molten low-melting metals is an effective way to reduce the electrical resistance of the friction zone of sliding electrical contact. [ABSTRACT FROM AUTHOR]

Ti-Al and Ti-Al-Co metal composites have been produced by shock-wave compaction using hexogen and ammonite explosives. The microstructure, microhardness, and temperature spectra of the real part of the complex magnetic susceptibility χ′( T) have been studied. The measurements have been performed in the course of isochronal annealings of the samples at temperatures progressively increasing in steps of 50 K. The values of χ′, which correspond to the isothermal sections of the spectra at 140 K and 400 K, as a function of the isochronal annealing temperature, χ′( T), have the form of asymmetrical bell-shaped curves. The maxima of these curves are in the region of the temperature of the α → β polymorphic transformation of cobalt. Possible reasons for this behavior of χ′ have been discussed. [ABSTRACT FROM AUTHOR]

Several metals (Sn, Cu and Ag) were coated on the surface of carbon nanotubes (CNTs) by electroless plating to improve the wettability between CNTs and the Sn matrix. The coated CNTs were characterised by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The results reveal that the metals are decorated effectively on the sidewalls of CNTs. The deposited metals are supposed to serve as the medium for interacting with the melted Sn matrix and achieve high strength interfacial adhesion. It was found that the Ag coated CNTs are wetted to a certain degree by melted Sn and embedded well in the matrix. While in the case of Sn and Cu coated CNTs, fewer CNTs are embedded in the Sn matrix because of desorption or oxidation. [ABSTRACT FROM AUTHOR]

Ammonia-borane (NH3BH3) has been investigated as hydrogen storage material for fuel-cell application because of its good gravimetric (19.6 wt%) and volumetric hydrogen density. Non-noble metals such as cobalt, nickel and copper were employed as catalyst and their combination was also tried as catalysts. For the effective scanning method for a number of compositions, a high throughput screening (HTS) test was used. Among the catalysts investigated, the ternary composite Ni60Co20Cu20/ACF (active carbon fiber) showed excellent performance in releasing the hydrogen from NH3BH3 solution, which can be recommended as a viable/suitable catalyst for fuel-cell system application, with some necessary basic improvements. [ABSTRACT FROM AUTHOR]

A very fine structure of mechanically alloyed Al–V2O5 composite was tested by means of transmission electron microscopy and X-ray energy disperse spectrum (EDS) analysis. Annealing of the composite was found to result in the intermetallic grains growth and an increase of the material porosity due to chemical reaction between components. Hot compression tests of as extruded and annealed samples confirmed high mechanical properties of the material at high deformation temperatures that result from very fine-grained and stable structure of the composite. [Copyright &y& Elsevier]

Metal composite materials are heterogeneous materials consisting of two or more different components bonded together internally. Special kinds of metal composites are produced by simultaneous plastic deformation of different metals. Process variables and characteristics of materials deformed simultaneously have an effect on the amount of deformation in each material, plastic zone, influencing the results of simultaneous plastic deformation. The present paper investigates the ability of dissimilar powder metallurgical (P/M) preforms to undergo simultaneous deformation using a special laboratory test. The influence of density ratio, thickness or volume ratio, type of deformation and total plastic strain on the strain experienced by individual metals are studied to establish the conditions of sound flow during simultaneous deformation.The results indicate that the simultaneous plastic deformation of dissimilar P/M preforms with different properties makes the deformation heterogeneous. The difference in the plastic strain experienced by each material increases with increase in the total plastic strain, volume or thickness ratio and deviation from the unit density ratio. The consolidation and metal matrix hardening mechanisms associated with the P/M preform deformation, strongly affect the deformation behavior of each metal and the onset of steady state deformation, during simultaneous deformation. Parameters such as volume ratio and type of deformation also strongly influence the simultaneous deformation results. [Copyright &y& Elsevier]

Plastic working of powder metallurgical (PM) material necessitates the development of fundamental data such as flow stress, densification behaviour, coefficient of friction, apparent strength coefficient, apparent strain hardening exponent, plastic Poisson's ratio, etc. In the present work compression and standard ring compression tests have been carried out to generate the fundamental data for simultaneous deformation of sintered steel and copper powder metallurgical preforms. The results reveal that the behaviour of individual materials during simultaneous deformation is strongly influenced by local micromechanical interactions at the metal - metal interface. In addition to this, the test conditions (iso-stress and iso-strain) strongly influence the severity of interaction. The interfacial friction coefficients are less than that of the same material when tested between hard tools. The optimal process parameters with higher interfacial friction, which can enhance the solid state joining of dissimilar materials, have been identified. The flow stress of the composite (steel - copper combination) during simultaneous deformation can be estimated if the flow stress of the individual materials comprising the combination/composite are known. With these studies, it should be possible to extend the inferences to the major deformation processes. [ABSTRACT FROM AUTHOR]

The equations for integral instantaneous characteristics of composite materials consisting of elastoplastic fibers and matrix are derived based on the known hypotheses of uniform strain or stress fields. The constitutive relations for a layered shell are obtained. The numerical algorithm elaborated is used to solve the stability problem for conical boron-aluminum shells under external pressure and axial compression. It is shown that the shells of medium thickness lose their stability under loads whose magnitude depends on the plasticity of the binder. The plasticity has a decisive influence on the choice of the optimum directions of reinforcement. If the parameters of a shell are such that the buckling occurs beyond the elastic limit, the shell must be reinforced in the direction of precritical stresses. However, this is possible only upon separate action of loads. [ABSTRACT FROM AUTHOR]

• TiB whiskers could be adjusted by varying the direction of heat extrusion. • Fatigue properties of TiB-reinforced titanium alloy depend on the TiB orientation. • Fatigue crack paths in titanium alloy are influenced by the TiB orientation. • Fatigue crack initiation resistance in titanium alloy is reduced by TiB whiskers. • Fatigue crack propagation resistance in titanium alloy depends on the TiB orientation. TiB-reinforced Ti-3Al-2.5V, in which TiB whiskers are oriented parallel to the direction of heat extrusion, was fabricated. To investigate the effects of TiB whisker orientation on fatigue properties in Ti-3Al-2.5V, four-point bending fatigue tests were conducted for plate-type specimens having three different orientations of TiB whiskers. The fatigue limit and fatigue life of Ti-3Al-2.5V having TiB whiskers, which are oriented parallel to the loading direction, were high. This is because the resistances of fatigue crack initiation and propagation were changed with the TiB orientation in Ti-3Al-2.5V. Thus, fatigue properties in the Ti-3Al-2.5V having TiB whiskers depended on TiB orientation. [ABSTRACT FROM AUTHOR]