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We report on a corroborative study of the structural, morphological and electrical property alterations of free-standing graphene oxide (GO) papers subject to thermal reduction. Structural analysis performed using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Raman techniques prove that the onset of major structural changes, characterized by removal of oxygen functionalities, occur in the 200–300 °C temperature range. The results are corroborated with related morphological changes observed using Scanning electron microscopy (SEM) and Atomic force microscopy (AFM) imaging. Elemental analysis shows the GO paper reduced at 600 °C to contain an 85 wt. % carbon content and a remnant oxygen level of 13.31 wt. %. At the highest reduction temperatures, we see evidence of vacancy-type defects impeding the overall effectiveness of the reduction process. Detailed electrical resistance measurements and current–voltage (I-V) profiling conducted using four-point probe method reveals a several orders of magnitude drop in the sample resistance once the reduction temperature exceeds 200 °C, in good agreement with the structural and morphological changes. The fundamental insights revealed through these studies will be important for future applications where the electrical and mechanical properties of free-standing GO and reduced graphene oxide (rGO) are exploited in practical devices. [ABSTRACT FROM AUTHOR]

Carbon papers (CPs) have been fabricated using wet-laying carbon fibers (CFs) and polyacrylonitrile (PAN) fibers. Scanning electron microscopy revealed that the PAN fibers tightly interconnected the CF junctions with the pores between the fibers. The tensile strength of the carbon webs (CWs) increased as the fraction of PAN fibers used as the binder increased. The CW fabricated with 0.15 wt% PAN fibers had a tensile strength six times greater than that of the CW without PAN fibers. Moreover, by mixing the CFs with PAN fibers in water, the CFs separated from each other in the webs due to the interruption of hydrophobicity between the CFs. After mixing with PAN fibers, the CWs were carbonized at 1200 °C in the presence of a phenolic resin. The PAN fibers maintained their morphology due to their high carbon content after carbonization. The electrical resistivity of the CPs with high PAN fiber content was significantly lower than that of a CP without PAN fibers due to the interconnection of the CFs by the carbonized PAN fibers. [ABSTRACT FROM AUTHOR]

Many important properties of bacterial cellulose (BC), such as moisture absorption capacity, elasticity and tensile strength, largely depend on its structure. This paper presents a study on the effect of the drying method on BC films produced by Medusomyces gisevii using two different procedures: room temperature drying (RT, (24 ± 2 °C, humidity 65 ± 1%, dried until a constant weight was reached) and freeze-drying (FD, treated at − 75 °C for 48 h). BC was synthesized using one of two different carbon sources—either glucose or sucrose. Structural differences in the obtained BC films were evaluated using atomic force microscopy (AFM), scanning electron microscopy (SEM), and X-ray diffraction. Macroscopically, the RT samples appeared semi-transparent and smooth, whereas the FD group exhibited an opaque white color and sponge-like structure. SEM examination showed denser packing of fibrils in FD samples while RT-samples displayed smaller average fiber diameter, lower surface roughness and less porosity. AFM confirmed the SEM observations and showed that the FD material exhibited a more branched structure and a higher surface roughness. The samples cultivated in a glucose-containing nutrient medium, generally displayed a straight and ordered shape of fibrils compared to the sucrose-derived BC, characterized by a rougher and wavier structure. The BC films dried under different conditions showed distinctly different crystallinity degrees, whereas the carbon source in the culture medium was found to have a relatively small effect on the BC crystallinity. [ABSTRACT FROM AUTHOR]

We disclose a method for the wet chemical etching of silicon (001) surface with a conical texture. This method involves a single-step etching process without additional surface treatments. The conical texture is compared to the pyramidal texture resulted from conventional chemical processes. Scanning electron microscopy reveals smaller dimensions of the surface cones as compared to the pyramids. Reflectance measurements show a slight decrease in the reflectivity for the samples with the conical texture as compared to the pyramidal texture. X-ray diffraction was performed to investigate the state of strain in the textured samples. In regard to the solar cell fabrication, we discuss in the paper the advantages of the conical texture as compared to the pyramid texture. [ABSTRACT FROM AUTHOR]

The carbothermal reduction of SiO2 gel containing filter paper (as carbon precursors) in argon was used to prepare SiC nanowires and nanoparticles. The resulting SiC ceramic, as well as the conversion mechanism of carbon/silica composites to SiC nanowires and nanoparticles, have been investigated by scanning electron microscopy (SEM), Transmission electron microscopy (TEM), x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TG) techniques. XRD and IR studies show that the materials, obtained from reaction at 1550 °C for 1 h in static argon atmosphere, are β-SiC. SEM and TEM reveal that SiC nanowires is single crystal wires with diameters ranging from 50–200 nm and their lengths over several tens of microns. According to thermodynamic analysis, SiC nanowires and SiC nanoparticles in the resulting SiC ceramic are formed by gas-gas reaction of SiO (g) and CO (g). [ABSTRACT FROM AUTHOR]

In this paper, anhydrous porous CuF2 with a micro-nano-hierarchical structure has been successfully fabricated via a precipitation method and a following solid-state reaction process. Scanning electron microscopy, transmission electron microscopy and N2 adsorption–desorption isotherms results confirm that the prepared porous CuF2 bulks are composed of loosely packed nanoparticles with a size range mainly between 30 and 50 nm, forming a micro-nano-hierarchical structure and possessing a large specific Brunauer–Emmett–Teller surface area of 24.93 m2 g−1. The porous CuF2 exhibits an outstanding initial discharge capability of 523 mAh g−1 at 0.1C and a superior rate capacity of 403 mAh g−1 at 5C with a cutoff voltage of 1.5 V versus Li/Li+. Moreover, electrochemical impedance spectroscopy, cyclic voltammetry and galvanostatic intermittent titration technique results verify porous structure can decrease the charge transfer resistance and boost the Li+ diffusion coefficient in CuF2. The method proposed in this work could be potentially used to synthesize other metal fluorides for high-performance lithium-ion batteries. [ABSTRACT FROM AUTHOR]

This paper reviews a literature survey on the usage of volcanic particle materials as an alternative filler material in polymer composites. Also, it highlights different types of volcanic particle materials and their potential effect on the performance of polymer composites. The review begins with Fourier transform infrared (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) analysis of different volcanic materials. Then, it reviews the thermal and mechanical properties of polymer composites that filled with different volcanic particle materials such as volcanic ash, pumice, perlite, and tuff. Reviewed articles have demonstrated that volcanic particle materials can serve as a polymer composite filler. However, there are several factors such as volcanic particle type, size, surface treatment, dispersion, filler concentration, and interfacial interaction with polymer matrix that should be considered and optimized to achieve a balanced polymer composite with its desired properties. Further, the review provides some insights on the gap in the research of volcanic particle material in polymer composites. In particular, the research of volcanic particle materials in different kind of polymers especially bio-based and recycled ones according to the cost-effective and green applications was suggested to be focused. [ABSTRACT FROM AUTHOR]

In this paper, the effects of different hygrothermal ageing conditions on the interlaminar shear mechanical properties of carbon fibre-reinforced polymer (CFRP) at room temperature and at a high temperature were studied. The changes in interface properties were characterized by macroscopic section analysis and scanning electron microscopy. The results demonstrated that the interlaminar failure strength of CFRP decreases nonlinearly with increasing ageing time, with an approximately exponential relationship. Under the same ageing conditions, the residual strength of high-temperature interlaminar shear is significantly lower than that at room temperature. By quantitatively studying the relationship between the failure strength of CFRP interlaminar shear and the absorbance intensities of functional groups, a failure strength prediction method was proposed. The verification results showed that the correlation accuracy can meet the requirements of engineering applications. [ABSTRACT FROM AUTHOR]

Inspired by inorganic oligomers, we herein develop a novel inorganic gel based on calcium oxalate oligomers, and the crystallization morphology has been studied initially in this paper. The prepared oligomer is translucent gel and can exist stably in ethanol, but in aqueous medium it will change from gel to powder. In the crystallization process, because of the volatile speed of solvent and capping agent TEA at different temperature, CaC2O4 oligomer gels (COOGs) exhibited distinct crystallization behavior and morphology. Compared with conventional inorganic crystallization, the crystallization process of the gel at room temperature shows a tendency to gradually extend to the inside of the gel. Moreover, the XRD pattern and SEM images shown that the COOGs achieved distinctly different crystal morphology under different temperature. These provide a preliminary research foundation for the crystallization behavior and control conditions of inorganic gels. [ABSTRACT FROM AUTHOR]

The chemical and physical features of metal organic frameworks (MOFs) at a molecular level are of great merit to understand structure–property relationships and, consequently, to aid in the design of improved high value products. This paper reports on the processing of one MOF-type material, namely MIL-101(Cr), by γ-ray irradiation at low doses up to 30 kGy. The optimum dose is determined to be 15 kGy, at which an increase in the adsorption of iodine of more than 40% is achieved in comparison with thermally activated un-irradiated MIL-101(Cr). Scanning electron microscopy, X-ray diffraction and the Brunauer−Emmett−Teller (BET) isotherms indicate a significant particle agglomeration and a preservation of both the unit cell topology as well as the mesoporous structure of MOF. Two-dimensional correlation Fourier transformation infrared and X-ray diffraction reveals that orientation is the driving force for structural alterations including water type, bonding and contents. These effects account for the increasing adsorption capacity of MOF after irradiation and suggest further exploitation of irradiation as a promising method for MOFs activation. [ABSTRACT FROM AUTHOR]

Alkaline-earth metal-based MOF has many merits such as light weight, environmental friendliness and low cost, but it has rarely been used in energy storage and capacitive deionization (CDI). This paper presents a facile method for the fast synthesis of small-size magnesium formate MOF (Mg-MOF) under mild conditions by linker-free incubation in the presence of Mg(CH3COO)2⋅ 4H2O and dimethylformamide. The formic acid was in situ formed as ligand to facilitate the formation of Mg-MOF. The effect of incubation time on the morphology of MOF crystals was investigated. The small and well-defined Mg-MOF particles with the size of ~ 18 nm were formed in 1 h incubation, characterized by scanning electron microscopy and X-ray diffraction. Following carbonization, the Mg-MOF-derived mesoporous carbon was obtained. N2-sorption isotherm confirmed the mesoporous structure. Cyclic voltammetry test indicated the good electric double-layer feature of the Mg-MOF-derived carbon electrode, and the impedance results showed the excellent conductivity. As a capacitor electrode material, it delivered the specific capacitances of 102 F/g by GCD (0.2 A/g). The Mg-MOF-derived carbon electrode was applied successfully for capacitive deionization (CDI) with a desalination capacity of 8.0 mg/g in a CDI device. A supper fast desalination rate of 1.1 mg/g/min was achieved due to the abundant mesoporous structure. The work provides a cost effective and environmentally friendly way for the synthesis of MOF-based carbon materials free of transition metal, and the prospects for CDI application have been demonstrated. [ABSTRACT FROM AUTHOR]

This paper aims to unveil effects of α colony and α plate parameters on tensile properties and impact toughness of Ti-55531 alloy with multilevel lamellar microstructures. Microstructures with different α colony and α plate sizes were prepared using varied heat treatments and analyzed by X-ray diffraction, scanning electron microscopy, electron back-scattered diffraction, transmission electron microscopy. Relationships of microstructure and strength, plasticity and impact toughness were discussed. Results indicate that tensile strength increases, while plasticity and impact toughness of the alloy decline with decreasing effective sizes (width/length ratio) of α colony (dc) and α plate (dα) and increasing of volume fraction of α phase. Both dc and dα follow the Hall–Petch principle with strength, and dc was determined to be the critical controlling parameter of strength owing to higher interfacial strengthening effect induced by α colony. However, plasticity is primarily related to dα. Moreover, impact toughness for both dc and dα follows the linear relation, but the coefficient of dα is higher. Furthermore, impact toughness is more dependent on plasticity than strength. Larger α plates lead to more mechanical twins during impacting and result in higher plasticity and impact toughness. Therefore, the impact toughness should depend more on the size of α plates. In order to unveil the influence of α plate size on impact deformation and microcrack initiation behavior of Ti-55531 alloy, the microstructural deformation and crack nucleation characteristics in the impact crack nucleation region were detected by TEM in detail; then, the schematic illustration for microstructural deformation and crack nucleation characteristics was made according to experiment results. [ABSTRACT FROM AUTHOR]

This paper presents research on the equilibrium phase fractions, microstructure, and tensile properties of a 0.2C–5Mn–1.5Al (mass %) steel with 0 or 0.5 (mass %) Si addition after intercritical annealing (IA), using thermodynamic simulation, scanning electron microscopy, transmission electron microscopy, X-ray diffractometry, and uniaxial tensile testing. The research results show that the addition of 0.5 Si (mass %) has no significant effect on the equilibrium phase fraction but influences the optimal IA temperature. Different IA temperatures result in the retained austenite having different morphologies. The retained austenite in the 730 °C sample (0.5 Si) has two different morphologies—polygonal and lath—while the 760 °C sample (0 Si) has only polygonal retained austenite. The optimal tensile properties of the 0.5 Si steel are better than those of the 0 Si steel due to the solution strengthening effect of Si and the higher stability of retained austenite. The tensile properties of the investigated 0.5 Si steel are excellent, with a tensile strength of over 1 GPa, elongation over 42.00%, and strength × ductility over 42 GPa%. [ABSTRACT FROM AUTHOR]

The aim of this paper is to present a novel negative temperature coefficient (NTC) thermistor based on A2Zr2O7 (A = Nd, Sm, Gd, Yb) zirconate ceramics with pyrochlore-type structure for high-temperature application. The zirconate ceramics were synthesized via a solid-state reaction method where rare-earth oxides and ZrO2 were used as starting materials. The physical structures were characterized by X-ray diffraction, scanning electron microscopy, and Raman spectroscopy. It was confirmed that Nd2Zr2O7 and Sm2Zr2O7 are pyrochlore phases, while Yb2Zr2O7 and Gd2Zr2O7 are defect fluorite phases. The electrical property investigated by using resistance–temperature measurements demonstrated that the prepared A2Zr2O7 zirconate ceramics exhibit a typical characteristic of NTC over a wide temperature range between 673 and 1273 K. Particularly, A2Zr2O7, in addition to having high activation energy to ensure better sensitivity, can still maintain higher resistivity under high-temperature environments. Furthermore, the resistivity of A2Zr2O7 is almost independent of the change in oxygen partial pressure. These properties are superior to the classical spinel-type or perovskite-type NTC thermistor, providing valuable information to explore new NTC thermistor for high-temperature applications. [ABSTRACT FROM AUTHOR]

A comprehensive understanding of solidification behavior of Mg–Al–Zn–Bi alloys is necessary for designing novel casting Bi-modified AZ alloys. In this paper, 21 Mg–Al–Zn–Bi alloys were prepared to investigate the phase constituents, morphologies, grain sizes and area fractions of precipitates in as-cast microstructures, as well as their phase transition temperatures and solidification paths by using X-ray diffraction, scanning electron microscopy, optical microscopy and differential scanning calorimetric techniques. It was found that the Bi addition leads to the formation of α-Mg3Bi2 phase, which became coarse flake as Bi content increased. Besides, the Bi addition can modify the morphology of eutectic γ-Al12Mg17 phase and refine the grain size of primary phase. Moreover, the measured area fractions of precipitates increased steadily as Bi content increased, which were comparable with the model-predicated values. After that, the calculated liquidus projections in the Mg-rich corner of Mg–Al–Zn–Bi quaternary system were employed for demonstrating the effects of Bi addition on the solidification sequences. Additionally, the phase transition temperatures predicted via Scheil solidification simulations agreed well with measured values. The present work indicated that the combination of experimental investigations and thermodynamic calculations can serve as an efficient method to obtain accurate and comprehensive solidification behavior of Bi-modified Mg–Al–Zn alloys. [ABSTRACT FROM AUTHOR]

Coordination bonding of Ni(II) tetraazamacrocyclic (TAMC) complexes to carboxylic groups of organic polymers and graphene oxide paper (GOP) is proposed for a facile generation of paramagnetic centers by combining two diamagnetic components. The coordination functionalization occurs under basic conditions in water solution at room temperature. The coordination configuration of central Ni(II) changes from tetracoordinated square-planar to hexacoordinated pseudooctahedral, which implies the conversion from low-spin to high-spin nickel centers. In the case of organic polymers, the coordination bonding of Ni(II) macrocycles gives rise to characteristic changes in coloration (from yellow-orange to violet-blue), as well as clearly manifests itself in UV–visible, FTIR and EPR spectra. In the case of GOP, in addition to evident changes in FTIR spectra, morphological alterations in the mat surface and an increase in the mat thickness are observed in SEM images, which can be explained by an intercalating effect of voluminous macrocyclic cations, as well as by partial disintegration of GOP structure due to the liquid-phase treatment. The effective magnetic moments of tetraazamacrocycles attached to organic polymers vary from 0.88 to 1.47 BM, whereas for GOP considerably higher values of 2.10 and 2.87 BM were obtained. [ABSTRACT FROM AUTHOR]

The present paper regards the development of polyurea/polyurethane (PUa/PU) and PUa/PU–silica hybrid shell microcapsules (MCs), loaded with Ongronat®2500, a commercial type of oligomeric methylene diphenyl diisocyanate with increased functionality, as core material. Ongronat® 2500 has a wide range of applications either for the production of rigid polyurethane foams and as cross-linking or self-healing agent. The MCs were achieved by a facile, one-pot process, consisting of an oil-in-water microemulsion system combined with interfacial polymerization processing, employing a higher reactivity isocyanate, toluene diisocyanate, to competitively contribute to the shell formation. Ethylenediamine, polyethylenimine (PEI), triethoxy(octyl)silane (n-OTES) and 3-(2-aminoethylamino) propyltrimethoxysilane (aminosilane) were tested as active, or "latent" active hydrogen (H) sources, and their effect on the MCs morphology, encapsulation yield, shelf life, shell's chemical structure and thermal stability was assessed. The MCs are aimed at the development of a new generation of adhesive formulations, which are mono-component, self-reactive, eco-friendly and with low health hazards, for industries such as the footwear, construction, aerospace and automotive. MCs' characterization was performed using Fourier transformed infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy. It was possible to obtain MCs with a high loading of Ongronat®2500, exhibiting a core–shell morphology, an increased shell resistance to temperature and improved shelf life. The combination of PEI and n-OTES led to the best compromise between encapsulation yield and shelf life. Finally, a confinement effect of the encapsulated macromolecules is herein shown for the first time, by the drastic narrowing of the NCO peak at the FTIR spectrum of the MCs. [ABSTRACT FROM AUTHOR]

In this paper, we report the efficient preparation of polyacrylonitrile-based carbon fibers (CFs) by increasing the stabilization temperature and shortening the stabilization time. The oxidized fibers (OFs) were firstly prepared from precursor fibers (PFs) with different diameters at high stabilization efficiency. The skin–core structure of the obtained OFs was studied by optical microscopy, scanning electron microscopy, atomic force microscopy and nanoscale infrared laser spectroscopy, which revealed that fine denier PFs were more suitable for high-efficient stabilization treatment. Moreover, fine denier PFs were stabilized using four different temperature profiles, and then carbonized under stationary processing conditions to fabricate CFs with different stabilization efficiencies. The skin–core structure, crystallite thickness and mechanical properties of the obtained CFs were tested by scanning electron microscopy, Raman spectra, wide-angle X-ray diffraction and tensile testing methods. Noteworthily, T400-grade CFs were achieved and the manufacturing time was reduced by increasing stabilization efficiency, thus lowering the production costs of CFs. [ABSTRACT FROM AUTHOR]

In this paper, the fluoro-polymer-coated multiwall carbon nanotubes (MWCNTs) were prepared by in situ atom transfer radical polymerization of 2-(perfluoroalkyl) ethyl methacrylate (FEMA) on the surface of MWCNTs. Scanning electron microscopy results showed that the fluoro-polymer on MWCNTs surface improved the dispersion and compatibility of MWCNTs in the poly(vinylidene fluoride) (PVDF) matrix. The PFEMA@MWCNTs/PVDF composites exhibited improved thermal stability and reduced crystallinity due to enhanced interface strength between MWCNTs and PVDF. Furthermore, nearly 100% polar phase PVDF formed after introducing high PFEMA@MWCNTs content into PVDF matrix. It was also found that PFEMA@MWCNTs-filled PVDF composites present advantages in increasing dielectric constants and decreasing loss tangents due to the restriction of interface polarization and leakage current. Based on the percolation threshold and ac conductivities, the PFEMA@MWCNTs/PVDF composites exhibit good insulation properties and are promising for high-performance dielectric composite applications. [ABSTRACT FROM AUTHOR]

The effect of high-density electroshocking on the solid phase transformation of Ti–6.6Al–3.4Mo alloy was studied in this paper. The microstructure at the same position of the specimens before and after electroshocking treatment with different parameters was characterized by the optical microscopy and scanning electron microscopy. The experimental results reveal that the refined and spheroidized primary α phase can be obtained under the appropriate treatment condition. Meanwhile, the fine orthorhombic α″ phase at submicron was discovered by the X-ray diffraction and transmission electron microscopy in the transformation products. A physical model was established to analyze non-uniform current distribution at microscale and to explain the spheroidization mechanism. The phase transition process was interpreted from the point of view of thermodynamics. [ABSTRACT FROM AUTHOR]

Layered double hydroxides (LDHs) are 2D ionic lamellar nanomaterials, which attract increasing interest for applications in different fields. This paper shows that their morphology is strongly affected by the microstructure of the substrate on which they grow. Zn–Al LDHs were grown in the same conditions on Al substrates with different microstructural features obtained from cold-rolled sheets by annealing at 265 °C for increasing soaking time up to 1 h. LDH morphology was then investigated through scanning electron microscopy observations. The homogeneous distribution of petals on the substrate surface mainly depends on grain size distribution. A bimodal grain size distribution in the substrate leads to the formation of petal clusters and a not complete covering of the surface. In the case of grains of large size the nucleation sites are the dislocations forming the walls of the cells, while owing to their low density, the dislocations inside the grains are not a relevant factor in determining the LDH morphology. [ABSTRACT FROM AUTHOR]

In this paper, the shape instabilities of Nb in in situ Cu-Nb microcomposite wires after exposed to different annealing treatments have been analyzed using scanning electron microscopy and transmission electron microscopy technologies. The results suggest that the thermal stability is related to misorientation among the adjacent grains at the triple joint. Most of the triple joints are composed of low-angle grain boundaries in Nb ribbons and Cu-Nb interfaces of (111)Cu//(011)Nb. These triple joints provide dragging force to interface motion so that neither the grains nor the interface boundaries show substantial changes below 500 °C. Above 500 °C, the Nb ribbons start to dissociate at the triple joints within Nb phase due to the stored energy by misorientation/distortion in Nb. Grooves and pits formed at these regions tend to promote the spheroidization of the Nb phase. Such results may enrich the studies on the microstructure evolution of Cu-based microcomposite. [ABSTRACT FROM AUTHOR]

In this paper, flower-like Ag nanocrystals and their fractal networks were successfully synthesized by gas-solution interface technique at the surface of AgNO3 water solution with the assistance of ammonium citrate and of gaseous N2H4 used as reductant. The synthesized flower-like silver structure consisted of a large number of petal-like silver nanoplates. They were characterized by scanning and transmission electron microscopy, absorption UV-Vis spectroscopy, and X-ray diffraction. In addition to the standard silver fcc modification, the nanostructures contained the hexagonal polymorph (4H-Ag) in the amount of about 5%. The effect of pH of the solution on the morphology of nanoparticles and on the silver crystal structure was examined. Depending on the time of treatment with gaseous hydrazine, it was possible to obtain either separate flower-like nanoparicles and their fractal networks, or continuous films formed by rather closely packed petal-like nanoparticles. The surface-enhanced Raman scattering effect was observed, and the most intense interaction of laser beam with the silver nanoparticles occurred when the solution side of the synthesized film was irradiated. [ABSTRACT FROM AUTHOR]

Micro/nanotopographical modification of biomaterials plays an essential role in the improvement of implants' cytocompatibility. In this paper, hierarchical micro/nanostructured surface was constructed to improve the titanium alloy cytocompatibility, which combined sandblasting, acid etching, and alkali heat treatment. The surface features were characterized using scanning electron microscope (SEM), laser scanning microscope, X-ray diffraction (XRD), and contact angle goniometer. A series of biological tests were carried out to evaluate cytocompatibility of bio-titanium alloy in vitro, including cell adhesion, counting, proliferation, osteocalcin expression, alkaline phosphatase (ALP) activity, and extracellular matrix mineralization. The results show that bio-titanium alloy with micro/nanostructured surface provided a beneficial interface which could promote the growth of osteoblasts. A uniform nanowire layer with high hydrophilicity was superposed on microstructures. Meanwhile, the biological tests indicate that hierarchical micro/nanostructures with micropits and nanowires could significantly promote osteoblasts' initial adhesion, proliferation, and differentiation. Moreover, the underlying mechanism of interaction between implants and cells was also discussed. This work proposes an effective approach to fabricate micro/nanostructured surface on titanium alloy for cytocompatibility improvement. [ABSTRACT FROM AUTHOR]

Scanning electron microscopy (SEM) combined with image analysis can provide a quantitative description of the area distribution of a porous structure, such as a paper coating. This is one of the few techniques where one can limit the measurement area strictly to the coating layer, fully excluding the base paper. It has been found that SEM cross-sectional porosity, defined as visible relative void area, and mercury porosimetry results agreed qualitatively to some degree but differed quantitatively. From an understanding of the differences in observations provided by the two methods, it is realised that comparison of void area distribution and intruded pore volume distribution, the latter including effects of entrance geometry to pores (mercury porosimetry and pore shielding), effectively describes the 2D to 3D transformation between the cross section and the pore network structure, i.e. a description of connectivity, in the unique case where the topology of the pore structure skeleton remains similar. Such structures are termed homeomorphisms. By studying the pore structural parameters of pigmented tablet structures, consisting of natural ground calcium carbonate with progressively increasing dose of latex binder, it is shown that the pore structural parameter of connectivity, and, hence, effective tortuosity/permeability, derived independently using the pore network model, Pore-Cor, can be deduced by forming the differences and correlations (convolution) between the two pore size distribution methods. [ABSTRACT FROM AUTHOR]

In this paper, copper coated carbon nanotubes (CNTs) was synthesized by decomposition of Cu(II) acetylacetonate (Cu(acac)2) in hydrogen atmosphere at 300 °C. The thickness of the copper coating was in nanoscale according to scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images, and Raman spectra indicated that certain intermediate bonds were formed between copper and the template CNTs. The crystalline structure of copper and its growth orientation were determined by X-ray diffraction (XRD) and selected area electron diffraction (SAED). The copper coating on CNTs had a face-centered cubic structure and its growth orientation was parallel to $$ (\bar 111) $$ planes. The method developed in this paper had the advantages of simplicity in both process control and experiment equipments, so that it might provide a possibility of large-scale production. [ABSTRACT FROM AUTHOR]

This paper describes the production and characterisation of low density polymeric foams used by the Atomic Weapons Establishment (AWE) Plasma Physics programme. Production and preparation of such foam samples for characterisation by scanning electron microscopy (SEM) are described. Examining non-conductive low density foam specimens by conventional SEM requires sputter coating with a very thin layer of gold to prevent overcharging the sample. This paper describes modifications to this process, which have illustrated the destructive effects of the sputtering process on these foams. Optimum conditions to minimise foam damage during sputtering have been determined. Low-vacuum SEM in conjunction with a charge cascade detector which enables non-conductive samples to be directly imaged has been used to reduce the damage to fragile foams. These results are compared with those taken of samples coated under optimum sputtering conditions. Using sputter coating time trials and an absorbed electron (AE) detector, it was revealed that the pore size of TMPTA foam was in the region of 0.1 μm, i.e. an order of magnitude lower than reported previously. Some proposed damage mechanisms are also discussed. [ABSTRACT FROM AUTHOR]

This paper reports the solvothermal synthesis of MoS nanospheres and nanosheets. The nanospheres were obtained using ammonium polysulfide as a sulfur source and have a mean diameter of about 100 nm. The nanosheets were assembled from a few lamellar layers and were obtained using thiourea as a sulfur source. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used in order to characterize the prepared powders. Conglomerate size and stability of the synthesized samples in hexane were studied with zeta potential. The four-ball method was used to assess the lubricating effect when these materials were used as additives in engine oil dispersions. The topography of the wear scar was analyzed using SEM, EDX, and 3D surface profilometry. The tribological properties of base engine oil containing the nanomaterials penetrated more easily into the interface space, and it formed a tribo-film at contact interface. The tribological performance showed that the synthesized nanosheets had superior anti-wear and friction-reducing properties as a lubrication additive compared with nanospheres, and the wear scar of balls lubricated with nanospheres revealed larger width compared to nanosheets. From the results, it is observed that nanosheets dispensed in oil have better tribological performance compared to nanospheres oil in terms of capability to reduce wear. [ABSTRACT FROM AUTHOR]

In this paper, injection-molded isotactic polypropylene (iPP) microparts and macroparts were respectively fabricated by the molds with different thickness under the same processing conditions. Comparative study on microstructure and mechanical property was carried out by means of scanning electron microscopy (SEM), two-dimensional wide-angle X-ray diffraction (2D-WAXD), two-dimensional small-angle X-ray scattering (2D-SAXS), differential scanning calorimetry (DSC) and tensile test. SEM images reveal that the two parts show distinctly different hierarchical structure. An obvious ‘skin–core’ structure is present for the macroparts, while a wide distribution of shish-kebab structure develops in both shear and core layer for microparts, exhibiting a specific ‘core-free’ morphology. 2D-WAXD, 2D-SAXS and DSC results show that microparts have higher orientation degree and crystallinity as compared to macroparts, which are responsible for the remarkably high tensile strength and modulus. Our work provides a good example for better understanding processing structure–property relationship of iPP through tuning their internal microstructure. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) random fibrous (RF) materials with bonded networks exhibit unique mechanical properties. In this paper, an inorganic RF material is fabricated and its compressive behavior is studied by experiment. Based on the experimental characterization, a 3D numerical model is constructed using a series of geometrical algorithms. Afterward, the statistical distribution of fiber segment aspect ratio is calculated using the numerical model, which is consistent with that measured from SEM photos. The compressive behavior of this RF material is simulated using finite element method (FEM). In the FEM model, the effect of fiber–fiber contact is realized by contact spring. The calculated results agree well with experimental data. Moreover, the predicted failure mechanism is verified by SEM observation. Finally, the FEM model is employed to investigate the influences of porosity on the elastic modulus and compressive strength of the RF material. [ABSTRACT FROM AUTHOR]

This paper investigates the enhancement of fly ash-based geopolymer with chitosan biopolymer. Unconfined compression and split tensile tests were carried out to investigate the effect of addition of small amount of N-carboxymethyl chitosan (0.05, 0.1, 0.15, and 0.2 wt% of fly ash) on the mechanical performance of fly ash-based geopolymer. Scanning electron microscopy (SEM) imaging was also conducted to study the microstructure of the chitosan enhanced fly ash-based geopolymer. The results indicated that the inclusion of N-carboxymethyl chitosan led to slight increase of the unconfined compressive strength and substantial increase of the tensile strength, the displacement at the peak tensile load and the pre-peak toughness, with the maximum increases at 0.1 wt% chitosan content. The SEM imaging indicated that the added N-carboxymethyl chitosan biopolymer coated and bridged the (geopolymerized) fly ash particles and led to the formation of a more condensed geopolymer network structure, thus enhancing the mechanical behavior of the geopolymer-biopolymer composite. However, when too much N-carboxymethyl chitosan was used, the excessive coating and encapsulation of un-reacted and partially hydrolyzed fly ash particles hindered their geopolymerization and adversely affected the mechanical behavior of the geopolymer-biopolymer composite. [ABSTRACT FROM AUTHOR]

In this paper, we report on the synthesis of pure silica (SiO) nano- and microwires by a non-catalytic process. The structure, morphology and properties of the products were examined by scanning electron microscopy, transmission electron microscopy, and energy dispersive spectroscopy. The microstructural analysis shows that the SiO wires are high purity silica and are completely amorphous; their diameter ranges from 70 nm to 2 μm. The fiber length varies from 100 μm to several mm. The wire manufacturing process involves reduced temperatures and times (1000 °C, 30 min) compared to other processes, without needing any catalyst and has been carried out on different kinds of substrates (SiC and Si). Successful growth of SiO wires on the surface of silicon microcantilevers has been demonstrated; they could be used as an alternatively way to enhance the sensor performances. [ABSTRACT FROM AUTHOR]

The influence of NH4+ on the preparation of carbonaceous spheres by a hydrothermal process was studied. A scanning electronic microscope and laser particle size analyzer were used to observe and measure the morphology and size distribution of the spheres. Fourier transform infrared spectroscopy was used to analyze the functional groups of the spheres. The results show that the addition of NH4+ has a significant influence on the morphology, size, and yield of the spheres. The slight addition of NH4+ greatly increases the diameter of the spheres and simultaneously improves their dispersion. With the change of NH4+ concentrations, the as-received spheres have sizes from 0.2 to 20 μm in diameter. The Fourier transform infrared spectroscopy results indicate that the C = O group disappears in the samples with NH4+ addition, different from the obvious peak at 1700.2 and 1305.6 cm in the samples with no NH4+ addition. A possible mechanism of the formation and growth of the spheres with the addition of NH is also proposed in the paper. [ABSTRACT FROM AUTHOR]

This paper is the first report on high strength glass-ceramics which mainly contain zirconia as crystalline phase. This is in contrast to previous reports on high strength glass-ceramics which contain low quartz as the crystalline phase. Glasses in the system MgO/Y2O3/Al2O3/SiO2 with zirconia as nucleating agent were melted. The samples were crystallised in a first step at 950 °C for different periods of time and in the second step at 1060 °C for 1 h. The prepared glasses and glass-ceramics were characterised using differential thermal analysis, dilatometry, X-ray diffraction, and scanning electron microscopy. As shown by X-ray diffraction after the first step in every analysed composition, zirconia was precipitated. With increasing crystallisation time and temperature and depending on the composition, the other phases such as β- or α-quartz solid solutions, spinel and indialite were precipitated. With higher yttria concentrations and increasing crystallisation temperatures during the second crystallisation step, the main crystalline phase was zirconia whereas the quartz solid solution was no longer observed. Bending strengths up to 450 MPa and Young′s moduli up to 115 GPa were obtained after the two subsequent crystallisation steps. Higher yttria concentrations resulted in an increase in density and microhardness. The maximum Vickers hardness was 10.5 GPa. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of CdS nanoparticles prepared in poly(vinyl alcohol) (PVA) in situ, to produce a series of CdS/PVA nanocomposite films, is described in this paper. The role of 2-mercaptoethanol as the surface ligand for the nanoparticles has been investigated. Different molar concentrations of the cadmium precursor have also been evaluated, aiming at the preparation of stable aqueous colloidal systems and polymeric films. UV-visible (UV-Vis) and photoluminescence spectroscopies together with scanning electron microscopy and transmission electron microscopy have been used for characterization of the growth kinetics and the relative stability of CdS nanocrystals in the polymeric matrix. The results clearly indicate the formation of hexagonal CdS nanoparticles embedded in the PVA matrix. PVA was not effective in stabilizing colloidal CdS nanoparticles against aggregation. However, it leads to a displacement of the first optical transition of CdS due to compressive deformation effect. The combination of PVA with 2-mercaptoethanol as surface ligands had a strong effect on the optical properties of the resulting embedded CdS nanoparticles. [ABSTRACT FROM AUTHOR]

This paper presents a study of microscale plastic deformation at the crack tip and the effect of microstructure feature on the local deformation of aluminum specimen during fracture test. Three-point bending test of aluminum specimen was conducted inside a scanning electron microscopy (SEM) imaging system. The crack tip deformation was measured in situ utilizing SEM imaging capabilities and the digital image correlation (DIC) full-field deformation measurement technique. The microstructure feature at the crack tip was examined to understand its effect on the local deformation fields. Microscale pattern that was suitable for the DIC technique was generated on the specimen surface using sputter coating through a copper mesh before the fracture test. A series of SEM images of the specimen surface were acquired using in situ backscattered electronic imaging (BEI) mode during the test. The DIC technique was then applied to these SEM images to calculate the full-field deformation around the crack tip. The grain orientation map at the same location was obtained from electron backscattered diffraction (EBSD), which was superimposed on a DIC strain map to study the relationship between the microstructure feature and the evolution of plastic deformation at the crack tip. This approach enables to track the initiation and evolution of plastic deformation in grains adjacent to the crack tip. Furthermore, bifurcation of the crack due to intragranular and intergranular crack growth was observed. There was also localization of strain along a grain boundary ahead of and parallel to the crack after the maximum load was reached, which was a characteristic of Dugdale-Barenblatt strip-yield zone. Thus, it appears that there is a mixture of effects in the fracture process zone at the crack tip where the weaker aspects of the grain boundary controls the growth of the crack and the more ductile aspects of the grains themselves dissipate the energy and the corresponding strain level available for these processes through plastic work. [ABSTRACT FROM AUTHOR]

In this paper, we report a new method for effective immobilization of Ag nanoparticles (AgNPs) decorated graphene oxide (AgNP/GO) composites onto thiolated single-stranded DNA decorated Au electrode (AuE) surface. The novel immobilization method is based on the coordination interactions and π-π stacking interactions between DNA bases and AgNP/GO composites. The morphologies of the AgNP/GO nanocomposites are characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). It is found that the AgNP/GO-decorated AuE exhibits remarkable catalytic performance for HO reduction. This HO sensor has a fast amperometric response time of less than 5 s. The linear range is estimated to be from 0.1 mM to 20 mM ( r = 0.998) and the detection limit is estimated to be 1.9 μM at a signal-to-noise ratio of 3, respectively. [ABSTRACT FROM AUTHOR]

This paper describes the result of investigation on PVA/FeCl nano composites fibres prepared by the electrospinning process. The effects of instrument parameters including solution concentration, electric voltage, tip-target distance, flow rate parameters on the morphology of electrospun PVA/FeCl fibres were evaluated. The produced composite fibres were characterized by scanning electron microscopy (SEM) and transmission electron microscope (TEM). Fibre mats of (PVA)/FeCl composite thin fibres, in the diameter of 500-1100 nm, were prepared by electrospinning. These microscopies show detailed morphologies of PVA/FeCl nano composites incorporating magnetic power. These novel composite fibres could be used in biomedical, catalyst and magnetic purpose. [ABSTRACT FROM AUTHOR]

The effect of Mn and P on types of precipitates as well as solute distributions in ultra-low carbon bake hardening (ULC-BH) steels was originally investigated in this paper. Three samples of hot-rolled ULC-BH steels (Ti-V, Ti-V-Mn, and Ti-V-P) were prepared. The types of precipitates in the three samples were characterized with scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and further calculated by Thermo- Calc. The different types of nanometer sized vanadium carbides are clearly characterized by SEM and TEM, and results of calculation and experiments are generally in agreement. Besides, the solute distributions in Ti-V-Mn and Ti-V-P steels were detected by three-dimensional atom probe (3DAP). It is found that no Ti, N, or S elements are present in both of the two steels, and the distribution patterns of the solute elements in the two steels are completely determined. Results show that SEM, TEM combining with 3DAP can well detect the existence of elements added into the bake hardening steels, and are very useful techniques for the base of the further investigation of mechanical properties and bake hardening phenomenon in bake hardening steels. [ABSTRACT FROM AUTHOR]

In this paper, polyaniline/multiwall carbon nanotube (PANI/MWCNT) composites were fabricated through an in situ polymerization method and were applied for the detection of aromatic hydrocarbon vapors. The composites were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, and Raman spectroscopy. The SEM results showed that the PANI was uniformly coated on the MWCNT, and the coating thickness was dependent on the mass ratio of aniline monomer to MWCNT. The response to aromatic hydrocarbon vapors was investigated in several hundreds ppm ranges. The sensor showed an increase in conductivity, and the maximum response measured at 1000 ppm was several tens of percent. [ABSTRACT FROM AUTHOR]

In this paper, a series of semi-interpenetrating polymer network (semi-IPN) hydrogels based on poly((2-dimethylamino)ethyl methacrylate)/poly ( N, N-diethylacrylamide) (PDMAEMA/PDEA) were synthesized by changing the initial PDMAEMA/DEA molar ratio at room temperature. The influence of this additive on the property of resulting PDEA hydrogels was investigated and characterized. The interior morphology by scanning electron microscopy (SEM) revealed that the semi-IPN hydrogels have interconnected porous network structures. The glass transition temperature ( T) of the semi-IPN hydrogels was observed by differential scanning calorimetry (DSC). Equilibrium swelling ratio (ESR), swelling and deswelling dynamics of the hydrogels responding to temperature and pH were investigated in detail. Compared to PDEA, the semi-IPN hydrogels exhibited excellent mutative values in response to an alternation of the temperature and pH, and showed fast swelling and deswelling rates in response to temperature and pH change. The release behaviors of the model drug, aminophylline, were found dependent on hydrogel compositions and environmental temperature. These results suggest that the stimuli semi-IPN hydrogel have potential application as intelligent drug carriers. [ABSTRACT FROM AUTHOR]

This paper details a comparison of the evolution in the microstructure of the α and β forms of gypsum plaster that occur during hydration. The comparison has been performed using a combination of rapid Nuclear Magnetic Resonance (NMR) relaxation measurements and Scanning Electron Microscopy images, acquired as a function of hydration time. The α plaster hydrates to an interconnected network of uniform gypsum crystals providing a homogeneous structure, whereas the β plaster exhibits growth of crystals with irregular shape leading to a more open pore network and a heterogeneous product. An additional NMR T2 relaxation time component is observed in the β plaster compared to the α plaster, suggesting the presence of large pores in the β plaster. This conclusion is confirmed by pore volume distributions determined from X-ray micro-computerised tomography (μ-CT) images of the set plasters. To the best of our knowledge, this is the first study of both forms of plaster utilising this combination of experimental techniques. The hydration kinetics have also been compared using one-dimensional NMR profiles, from which effective rate constants are determined. Consistent with previous results, the hydration reactions of the α and β forms of plaster are seen to occur at very different rates: the α plaster has a short initiation period and a slow hydration reaction. In contrast, the β plaster has a long initiation period, although the hydration reaction proceeds more rapidly thereafter. This work demonstrates the applicability of several NMR techniques to monitor, in situ, the hydration kinetics and microstructural evolution in plaster pastes, which will be crucial to the further understanding of mechanical properties (e.g. moisture transport) in these systems. [ABSTRACT FROM AUTHOR]

Anodized titanium-oxide containing highly ordered, vertically oriented TiO2 nanotube arrays is a nanomaterial architecture that shows promise for diverse applications. In this paper, an anodization synthesis using HF-free aqueous solution is described. The anodized TiO2 film samples (amorphous, anatase, and rutile) on titanium foils were characterized with scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. Additional characterization in terms of photocurrent generated by an anode consisting of a titanium foil coated by TiO2 nanotubes was performed using an electrochemical cell. A platinum cathode was used in the electrochemical cell. Results were analyzed in terms of the efficiency of the current generated, defined as the ratio of the difference between the electrical energy output and the electrical energy input divided by the input radiation energy, with the goal of determining which phase of TiO2 nanotubes leads to more efficient hydrogen production. It was determined that the anatase crystalline structure converts light into current more efficiently and is therefore a better photocatalytic material for hydrogen production via photoelectrochemical splitting of water. [ABSTRACT FROM AUTHOR]

Composite laminates on the nanoscale have unique properties, such as high strength, high wear resistance, and biocompatibility. In this paper we report on the nanoindentation behavior of a model metal–ceramic nanolaminate consisting of alternating layers of aluminum and silicon carbide (Al/SiC) processed by PVD on a Si substrate. Composites with different layer thicknesses were fabricated and the effect of layer thickness on Young’s modulus and hardness was quantified. The effect of indentation depth on modulus and hardness was studied. The damage that took place during nanoindentation was examined by cross-sectioning the samples by focused ion beam (FIB) technique and imaging the surface using scanning electron microscopy (SEM). Finite element modeling (FEM) of nanoindentation of nanolaminates was conducted. The damage patterns observed in experiments were qualitatively supported by the numerical simulations. [ABSTRACT FROM AUTHOR]

The present paper discusses different processing technologies for fabrication of novel 45S5 Bioglass®-derived glass–ceramic scaffolds with tailored porosity gradient for potential application in bone tissue engineering. Different types of scaffolds with continuous or stepwise gradient of porosity were produced by the foam replication technique, using preformed polyurethane (PU) foams as sacrificial templates. After preforming the PU foams in metallic moulds, they were dipped in a 45S5 Bioglass®-based slurry and subsequently heat treated in a chamber furnace up to 1100 °C. During heating, the organic phase is burned out and the glass sinters and partially crystallises. By using this new approach, Bioglass®-derived glass-ceramic scaffolds with different shapes and porosity profiles were designed. Scanning electron microscopy (SEM) showed that all samples have highly interconnected porous structure, with specific porosity gradients. By modifying the shape and dimensions of the metallic mould, bioactive glass–ceramic scaffolds with complex shapes and different degrees of porosity gradient could be obtained. [ABSTRACT FROM AUTHOR]

A study of the structural characteristics of the composites [Pb(Fe0.5Nb0.5)O3(PFN)] x -[Cr0.75Fe1.25O3(CRFO)]100− x ( x = 0 (CRFO100), 10, 50, 90, 100) was performed in this work. The compounds PFN100 and CRFO100 were prepared by conventional solid-state method and investigated by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and 57Fe Mössbauer Spectroscopy techniques. The X-ray analysis shows that PFN100 is tetragonal and the CRFO100 phase has a trigonal symmetry. The refinement of all the composites was also performed and discussed in this paper. The Mössbauer spectrum for the composite samples shows a paramagnetic doublet and a sextet probably assigned to a magnetic phase associated to Fe+3. For the sample PFN100, only a magnetic field of 49.5 T (isomer shift (δ) = 0.21 mm/s) was detected. For the composite sample, the δ and Δ are typical of Fe ions at sites of octahedral coordination. [ABSTRACT FROM AUTHOR]

The paper demonstrates the efficacy of natural rubber-g-poly (styrene-co-acrylonitrile) (NR-g-SAN) copolymers as impact modifier for SAN. The impact behaviour of SAN /NR-g-SAN blends were studied as a function of cross-link density of NR, percent grafting, rubber content in the blend and the AN content in the grafted chain. The cross-link density of NR had no significant effect on impact strength of the blends whereas increase in percent grafting (PG) of the rubber significantly improved the impact strength. Thus the impact strength increased four times when the PG of the rubber was increased from 34.2 to 65%. Further increase in PG decreased the impact strength. Similar trend was observed on increase in the rubber content, the maximum impact strength was observed at 20% rubber. The impact strength also depended on the acrylonitrile content of the grafted chain. Tensile and flexural strength and modulus of these blends were not influenced by PG and AN content in the grafted chain whereas these properties decreased with the increase in the rubber content. Scanning electron microscopic studies of the impact fractured surfaces showed cavitation of rubber particles and craze induced matrix deformation. Dynamic mechanical studies confirmed the two-phase structure of these blends. [ABSTRACT FROM AUTHOR]

The paper presents an electron microscopy study of the macro, micro and nanostructure of titania nano-tubes formed by electrochemical anodisation of titanium in a fluorine containing electrolyte. Scanning electron microscopy (SEM) is used to examine the overall structure of the nano-tubes formed under potentiostatic conditions. Transmission electron microscopy (TEM) has been used to examine the structure of the oxide layer of a sample anodised for a relatively short period (30 min) and provides a new insight into the formation of titania nano-tubes. The fluorine ions are able to nucleate sites on the titanium metal and generate a series of interconnected cavities or pores in the oxide complex formed, allowing current to flow within this film. Under specific conditions the cavities and randomly dispersed pores can align in the direction of the applied electric field and link up to generate an array of tubes, where the passage of ions and water is optimised. We also suggest that oxygen evolution at the anode may play a role in the development of the nano-tubes. [ABSTRACT FROM AUTHOR]

The diffusion welding of carbon steel to aluminium may be achieved when the temperature and compression of the weld metal allows diffusion at the interface between both components; the degree of interdiffusion largely determines the quality of the welded joint. Such diffusion processes can take place under vacuum. However, in this paper, we report that high quality welds can be achieved without the use of vacuum or reducing atmospheres by applying sufficient compression to give very high levels of plastic deformation of an Al layer sandwiched between layers of carbon steel at 550 °C in laboratory air. The resulting structures were characterised using scanning electron microscopy, transmission electron microscopy and microanalysis, which showed that, under these conditions, Fe diffused across the interface into the Al layer. [ABSTRACT FROM AUTHOR]

This paper presents the results of a study on the weldability of a duplex stainless steel, Avesta 2205, carried out by GMAW (MIG) pulsed arc welding process. An AISI 2209 electrode (AWS A/SFA 5.9, ER2209) was used as filler metal. The study was focused on the N2 content in the shield gas, from 0% to 6.4%. Firstly, a microstructural characterization of the welds using scanning electron microscopy (MEB-EDX) was carried out. Also, in order to study the microstructural changes originated by the welding thermal cycles and the % content of the N2, the ferrite content in the weld pool and heat affected zone (HAZ) were determined. Vickers hardness, tensile and bending tests were performed to determine the mechanical properties of joints and hence the influence of N2 addition without decrease in the mechanical properties. Finally, the joints were examined for susceptibility to intergranular corrosion using the Standard ASTM 262 93, practice A. The optimal content of N2 in the shield gas is included between 3% and 5%, which attain to obtain a 94% base material UTS. [ABSTRACT FROM AUTHOR]