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In this study, the forms of occurrence of impurity elements in silicon carbide (SiC) with different particle sizes were systematically investigated using a combination of X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectrometry (ICP-OES), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The experimental results showed that in SiC powders prepared using the Acheson process, the contents of O, free-Si, free-C, and Fe impurities are high, and those of other trace impurity elements follow the order: Ti > Al > Ni > V. Moreover, O impurities mainly cover the SiC particle surface in the form of amorphous SiO2. Fe impurities exist around SiC particles as Fe2O3, FexSiy, FexSiyTiz, and FexAlySiz phases. Impurity elements are often introduced during the smelting of SiC and/or during milling or subsequent storage.

Recent studies suggested that the interactions between particles can induce aggregative nucleation and growth processes beyond those predicted by the traditional LaMer model of nanoparticle formation, but their nucleation and growth processes are still unclear. Here, we report a simple way to control the interaction between nanoparticles by manipulating the oleylamine (OAm) adsorbed on the surface of the nanoparticles. The size distributions of Ag nanoparticles produced at different reaction pressures were monitored as evidence for aggregative growth. From these kinetic data, the aggregative nucleation rate (Γ) of primary Ag nanoparticles under a 0.01 MPa was demonstrated to be faster than that under atmospheric pressure. This leads to a higher uniformity of Ag nanoparticles in a shorter time (10 min) than that achievable with previous methods. Furthermore, Ag nanoparticles supported on TiO2 exhibited a remarkable performance in the catalytic reduction of 4-nitrophenol (4-NP). After 4 min, 4-NP was completely reduced into 4-aminophenol (4-AP).

Hydrogen is a clean fuel widely used in fuel cells, engines, rockets and many other devices. The catalytic decomposition of methane (CDM) is a COx-free hydrogen production technology from which carbon nano materials (CNMs) can be generated as a high value-added byproduct for electrode, membranes and sensors. Recent work has focused on developing a low cost catalyst that could work without rapid deactivation by carbon deposition. In this review, the economic and environmental evaluation of CDM are compared with coal gasification, steam reforming of methane, and methanol steam reforming in terms of productivity, CO2 emissions, and H2 production and cost. CDM could be a favorable technology for on-site demand-driven hydrogen production on a small or medium industrial scale. This study covers the Fe-based, Ni-based, noble metal, and carbonaceous catalysts for the CDM process. Focusing on hydrogen (or carbon) yield and production cost, Fe-based catalysts are preferable for CDM. Although Ni-based catalysts showed a much higher hydrogen yield with 0.39 molH2/gcat./h than Fe-based catalysts with 0.22 molH2/gcat./h, the hydrogen cost of the former was estimated to be 100-fold higher ($0.89/$0.009). Further, the CDM performance on different types of reactors are detailed, whereas the molten-metal catalyst/reactor is suggested to be a promising route to commercialize CDM. Finally, the formation mechanism, characterization, and utilization of carbon byproducts with different morphologies and structures are described and analyzed. Versus other reviews, this review shows that cheap Fe-based catalysts (10 tons H2/1 ton iron ore) and novel molten-metal reactors (95% methane conversion) for CDM are feasible research directions for a fundamental understanding of CDM. The CNMs by CDM could be applied to the waste water purification, lubricating oils, and supercapacitors.

Catalytic decomposition of methane (CDM) is a promising technology for producing COx-free hydrogen and nano-carbon, meanwhile it is a prospective substitute to steam reforming of methane for producing hydrogen. The produced hydrogen is refined and can be applied to the field of electronic, metallurgical, synthesis of fine organic chemicals and aerospace industries. However, the CDM for COx-free hydrogen production is still in its infancy. The urgent for industrial scale of CDM is more important than ever in the current situation of huge COx emission. This review studies CDM development on Ni-based, noble metal, carbon and Fe-based catalysts, especially over cheap Fe-based catalyst to indicate that CDM would be a promising feasible method for large hydrogen production at a moderate cheap price. Besides, the recent advances in the reaction mechanism and kinetic study over metal catalysts are outlined to indicate that the catalyst deactivation rate would become more quickly with increasing temperature than the CDM rate does. This review also evaluates the roles played by various parameters on CDM catalysts performance, such as metal loading effect, influences of supports, hydrogen reduction, methane reduction and methane/hydrogen carburization. Catalysts deactivation by carbon deposition is the prime challenge found in CDM process, as an interesting approach, a molten-metal reactor to continually remove the floated surface solid carbons is put forwarded in accordance to overcome the deactivation drawback. Moreover, particular CDM reactors using substituted heating sources such as plasma and solar are detailed illustrated in this review in addition to the common electrical heating reactors of fixed bed, fluidized bed reactors. The development of high efficiency catalysts and the optimization of reactors are necessary premises for the industrial-scale production of CDM.

Catalytic methane decomposition was investigated over 40 wt% Fe/Al2O3 catalyst in fluidized bed reactor (FLBR). After optimization of FLBR conditions in terms of catalyst bulk density, particle size, minimum fluidization velocity, and the catalyst bed height, the catalyst activity and stability tests were conducted by comparison with a fixed bed reactor (FBR). Although a similar stable methane conversion was obtained over both reactors, the pressure drop during 35 min operation of FBR was 9 times higher than that of FLBR, which indicated the possibility of continuous operation of methane decomposition process over FLBR. Further, the influence of the space velocity, feed dilution and regeneration on catalysts reactivity was studied in FLBR to conclude that a reaction condition of 12 L/gcat∙h, feed of 20%H2–80%CH4 and CO2-regeneration of deactivated catalysts may be favourable for operating methane decomposition in FLBR continually and effectively to provide stable hydrogen.

A series of 0.2 wt% Pd/Sn0.9Ce0.1O2 catalysts were prepared by impregnation method based on the pre-synthesis of Sn0.9Ce0.1O2 support prepared by co-precipitation method, and then characterized by Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman, CO chemical adsorption and hydrogen temperature-programmed reduction (H2-TPR) techniques. The effect of calcination temperature of the composite oxide support on the catalytic performances of the Pd/Sn0.9Ce0.1O2 catalyst for the CH4 total oxidation was studied. It is found that the catalytic activity of the Pd/Sn0.9Ce0.1O2 catalyst increases with the increase in calcination temperature of the Pd/Sn0.9Ce0.1O2 support. The 0.2 wt% Pd/Sn0.9Ce0.1O2/1100 catalyst (the Pd/Sn0.9Ce0.1O2 support was calcined at 1100 °C) exhibits the best reactive activity (T10 = 255 °C). The excellent activity of the 0.2 wt% Pd/Sn0.9Ce0.1O2/1100 catalyst should be attributed to the high reducibility of PdO, the excellent oxygen mobility of the support and the high content of active Pd2+ species on the Pd/Sn0.9Ce0.1O2 catalyst.

In this work, a series of iron-containing materials (not laboratory-synthesized but from natural, industrial raw materials, by-products or wastes), such as iron concentrate powder, fine/coarse ash and steel slag from steel plants and volcanic mud powder, were investigated as catalysts for methane decomposition. These catalysts exhibited relatively good methane conversion under the following conditions: 2.0 g of catalyst, 50 mL/min CH4, 900 °C for 5 h, even without hydrogen pre-reduction. Fe2O3 species on these samples were found to be gradually reduced by methane to Fe3O4, FeO and then finally into Fe0 active species. When methane decomposed onto the Fe0 active sites, Fe3C species would form to deposit graphite around themselves to finally form carbon nanomaterials, showing possible application in the oxygen evolution reaction and in Li-ion batteries as anode electrodes. Furthermore, using the best catalyst, iron concentrate powder, the effect of temperature and gas hourly space velocity was studied, where 900 °C and 3 L/gcat·h were determined as the optimized reaction conditions to reach the highest carbon/hydrogen yield.

In bearing applications, the development of new materials has become a focus of scientific research in order to make bearing systems smaller and rotate more accurately. Bulk metallic glass (BMG), which has high strength, stiffness and resistance to corrosion, is becoming a promising candidate for bearing and shaft materials. When used as shafts, the friction feature of BMG needs to be evaluated comprehensively. In this work, the friction and wear properties of Ni-based, Zr-based, and Cu-based BMGs sliding against brass lubricated with lithium grease were investigated, using traditional bearing materials (GCr15 steel) as comparison. The results showed that the wear mechanism of the BMGs was primarily abrasive, supplemented by an adhesive wear behavior when sliding against brass plates, just like GCr15 steel. The wear loss of the friction pair (brass plates) increases when the applied normal load increases and the sliding speed decreases. Compared with GCr15 steel, BMGs exhibit better friction performance at low sliding speed, and Ni-based BMG always exhibits a smaller wear loss, especially under large load and low sliding speed. The wear loss of brass plates against Ni-based BMG pin is 24.3% lower than that against GCr15 steel under an applied load of 10 kg, which indicates that Ni-based BMG is an attractive bearing and shaft material for industrial application.

A photocatalyst iron phthalocyanine/calcium alginate gel bead (FePc@SA) was prepared through the mixture including iron tetra (N-carbonylacrylic) aminophthalocyanine (FePc) and sodium alginate dropped into 5 % (w/v) CaCl2 solution to get gel beads. The color of gel ball was black and the average diameters of gel ball before and after drying were 3.19 mm and 1.20 mm, respectively. Methyl orange was selected as a substrate to investigate the photocatalytic activity of FePc@SA. The results shown that the remaining rate of methyl orange was 19.51 % under the condition of methyl orange 10 mg/L 25 mL, pH value was 3, the dosage of H2O2 was 50 μL, FePc@SA was 0.2 g and visible light irradiation for 3 h. The results indicated that FePc@SA/H2O2 system had an obvious synergistic effect on photocatalytic oxidative decolorization of methyl orange. The decolorization process conformed to the first order kinetics equation, and the half-life of FePc@SA was 76.7 min. Simple preparation methods and excellent photocatalytic properties made FePc@SA became an ideal high performance photocatalytic material, which was applied to deal with wastewater containing organic pollutants.

Oxidative decolorization of azo dyes with a heterogeneous catalyst copper phthalocyanine supported Mg-Al hydrotalcites was studied and the influence factors such as initial pH value, temperature, H2O2 and CuPc-LDHs/H2O2 system were discussed. The results indicated that acidic solution and high temperature were conducive to oxidative decoloration of methyl orange. CuPc-LDHs/H2O2 system showed excellent oxidative decoloration capacity to remove azo dyes. The effects of oxidative decolorization of azo dyes were related to the molecular structure and weight of azo dyes. Oxidative decoloration effects followed the order as congo red > amido black > methyl blue> methyl orange> methylene blue.

Surface modification of nanoAl2O3 with stearic acid by dry method was researched. The structures of nanoAl2O3 before and after modified were characterized by IR. The modification effect on nanoAl2O3 was measured with the activation index. In addition, the influence factors of modifier dosage, modification time and modification temperature were also discussed. The results showed that nanoAl2O3 had been successfully modified with stearic acid. The hydrophily and lipophilicity experiments indicated that modified nanoAl2O3 possessed lipophilicity property and could disperse in xylene. The optimal conditions of modification were as follows: the stearic acid was 7.5 wt%, based on the quality of nanoAl2O3, modification time was 50 min and temperature was 150 ○C.

A series of novel cross-linked poly N-isopropylacrylamide (PNIPAM)/poly diallyl dimethyl ammonium chloride (PDMDAAC) semi-IPN hydrogels were synthesized through free radical solution polymerization in water at 30°C. FTIR was used to characterize the structure of resultant hydrogels. The pH and temperature sensitivity of hydrogels were systematicly studied, and the swelling properties of hydrogels were also explored. The results show that the semi-IPN hydrogels have both temperature and pH sensitivities. The hydrogels exhibit fast swelling rate and excellent stimuli-responsive behavior.

We have presented and demonstrated a method for the fabrication of various complicated microstructures based on dynamically controlled patterned vector optical fields (PVOFs). We design and generate dynamic PVOFs by loading patterned holograms displayed on the spatial light modulator and moving traces of focuses with different patterns. We experimentally fabricate the various microstructures in z-cut lithium niobate plates. The method we present has some benefits such as no motion of the fabricated samples and high efficiency due to its parallel feature. Moreover, our approach is able to fabricate three-dimensional microstructures.

Fully amorphous Zr48Cu43-xAl7Ag2Nix(x=0, 2, 4, 6, 8 at. %) alloy system synthesized by Cu mould casting method were utilized to study corrosion behavior due to the poor corrosion resistance of Zr-Cu-Al-Ag alloy system by addition of Ni. High temperature DSC revealed that the Zr-based alloy system still maintained good glass-forming ability and thermal stability with the addition of Ni element. The result obtained from both the immersion test and the potentiodynamic polarization test showed that the addition of Ni element significantly improved the corrosion resistance compared to the Ni-free Zr-based alloy system. SEM graph showed a phenomenon of corrosive pit where there existed corrosion deposits as well as cellular textures and microcracks. In summary, proper addition of Ni could modify the corrosion resistance of the Zr-based alloy system.

Zr63.78Cu14.72Ni10Al10Nb1.5 BMGs (bulk metallic glasses) were cast at the melt temperatures ranging from 1,073 to 1,313 K with the same interval of 40 K. The structure, thermal, and mechanical properties of the BMGs were investigated by XRD, DSC, HRTEM, dilatometric measurements, micro-hardness tests, and uniaxial compression. The results indicate that the higher the casting temperature, the fewer the nano-crystallites, the more the free volumes, and the lower the micro-hardness in the BMGs, leading to the larger plastic strains. The plasticity of BMGs deteriorates with the increase of nano-crystallites as decreasing the casting temperature. The free volume, instead of the nano-crystallites, favors the plastic deformation in Zr63.78Cu14.72Ni10Al10Nb1.5 BMGs. The microstructures and mechanical performance of BMGs are closely affected by the casting temperature. The preparing parameters are important to improve the plasticity of the BMGs.

Magnetite particles were confirmed to deposit in the radula of chiton Acanthochiton rubrolineatus, and these magnetite particles presented as chip-shaped pieces which were 150 nm in width. Many nano-scale crystals constructed each piece of the magnetite particles. The mean size of a single crystal was 52 nm in diameter. Calcium composites were found to coexist with iron minerals. The total amount of magnetite in the chiton radula was 10% (w/w) of the radula weight, and 41% (w/w) of the total minerals. Eight metal elements were measured in the chiton radula, among which iron was a major element (14.6%, w/w) of the radula, followed by sodium, magnesium, calcium, potassium, chromium, manganese and cobalt in turn.

The magnetic anisotropy of the whole radula, the major lateral radula teeth, and magnetic material in the major lateral radula teeth of the chiton Acanthochiton rubrolinestus LISCHKE have been studied by a magnetic torque meter and superconducting quantum interference device (SQUID) magnetometer. The length and width axes of the teeth are the easily magnetized axes, while the thickness axis is difficult to magnetize. The width and thickness axes of the radula are the easily magnetized axes, and the length axis is difficult to magnetize. The measurement results of the whole radula and the major lateral radula teeth agree well with each other. The magnetic anisotropy of the magnetic material is given as well as a possible distribution of the magnetic material in the major lateral radula teeth.

We numerically and experimentally explored generation and regulation of subwavelength multiple focal spots produced by tight focusing patterned vector optical fields (PVOFs). We presented a modified Richard-Wolf diffraction integration method suitable for the tight focusing of the PVOFs. By tailoring the spatial geometry and the polarization distributions of the PVOFs, simulations show that the diverse spatial configurations of subwavelength multiple focal spots can be achieved. To verify our idea, we experimentally generated the theoretically calculated examples of femtosecond PVOFs, then tightly focused them on the surface of the crystalline silicon wafers, and finally characterized the morphologies of modified surfaces. The SEM (scanning electronic microscopy) images confirmed that the experimental results are in good agreement with the simulations. Based on the diverse controlling degrees of freedom of PVOFs, the resultant subwavelength focal fields are flexible and powerful in parallel processing, optical manipulation and so on.

We present a scheme for realizing femtosecond multi-filamentation with designable quantity and locations of filaments, based on the control of multi-focal spots formed by patterned optical fields (POFs) composed of multiple individual optical fields (IOFs). A computer-controlled spatial light modulator is used to engineer the POFs. In particular, we introduce a blazed phase grating in any IOF, which increases a degree of freedom, making the engineering of multi-focal spots becomes more flexible. We achieve experimentally the aim controlling femtosecond multi-filamentation in a K9 glass. Our scheme has great flexibility and convenience in controlling the multi-filamentation in quantity and locations of filaments and strength of interaction between filaments.

In this paper, a series of nano-titanium carbide doped polyimide (nano-TiC/PI) composite films were successfully prepared via in situ polymerization. Before addition, the TiC nanoparticles were modified by oleic acid (OA) to improve its dispersity in PI matrix. The microstructures, mechanical properties and dielectric properties of OA-modified TiC doped PI composites were investigated and compared with that of the pure-TiC/PI composites. Scanning electron microscopy (SEM) analysis showed that the dispersity of TiC nanoparticles modified by oleic acid in composite films was better than the pure TiC nanoparticles without modified. Results from mechanical property tests, including the tensile strength and the elongation at break, indicated that the addition of TiC nanoparticles decreased the mechanical properties of PI films. Compared with the pure-TiC/PI composite films, the mechanical properties of the OA-modified TiC/PI composites got a slight improvement, which was the mechanical properties of composite films with 20 vol.%. OA-modified TiC addition increased slightly (86.3 N/mm2 and 5.5% respectively), nevertheless, the pure-TiC/PI composites were just 65 N/mm2 and 3% respectively. The dielectric constant of 20 vol.%. TiC nanoparticles modified by OA doped PI composite film showed an average permittivity as 83, which was about 1.5 times higher than that of pure-TiC/PI composite films (55). However, the dielectric loss only rose slightly. Results of dielectric breakdown test indicated that the average breakdown field strength was improved over 67% (57 KV/mm) than pure-TiC/PI composites with 5 vol.%. (34 KV/mm). Therefore, the development of these novel polyimide composite films with favorable dielectric properties is immeasurably potential for embedded-capacitor applications.

Two-dimensional near-wavelength microstructures have been fabricated on a copper film and a silicon wafer by femtosecond vector optical fields with different spatial polarization distribution, at a central wavelength of 800 nm, pulse duration of ∼70 fs, and a repetition rate of 1 kHz. Laser-induced ripples appear at the ablated region on silicon when the laser fluence is above the ablated threshold. When the number of the irradiated pulses increases, ripples with interspace larger than the wavelength could be observed, while the dimension of the ablated region has a slight variation. In the induced microstructures on a copper film, the microstructures in a ring have been observed under the irradiation of a few pulses. Under the irradiation of the multipulse femtosecond vector field, differently from the condition of the silicon, the induced microstructures on the metallic copper surface exhibit the anisotropic extending feature dependent on the polarization distribution of the vector field. The physics behind this unique feature is the anisotropic excitation and propagation of surface plasmon, caused by the coupling of the subsequent irradiation pulses with the existing microstructure. In this case, the surface plasmons resonance in the induced 2D microstructures is closely related to the induced grating structures on the surface.

We present and demonstrate an approach for femtosecond laser processing by using patterned vector optical fields (PVOFs) composed of multiple individual vector optical fields. The PVOFs can be flexibly engineered due to the diversity of individual vector optical fields in spatial arrangement and distribution of states of polarization, and it is easily created with the aid of a spatial light modulator. The focused PVOFs will certainly result in various interference patterns, which are then used to fabricate multi-microholes with various patterns on silicon. The present approach can be expanded to fabricate three-dimensional microstructures based on two-photon polymerization.

We propose a flexible method to record and reconstruct vector fields with space-variant polarization distribution in c-cut Fe-doped LiNbO3, based on photorefractive two-wave mixing. To our knowledge, this is the first approach for the reconstruction of vector fields without using the photoinduced anisotropy of the recording material.

Two-dimensional near-wavelength microstructures have been fabricated on copper film by femtosecond vector optical fields with different spatial polarization distribution, at a central wavelength of 800 nm, a pulse duration of ∼70 fs, and a repetition rate of 1 kHz. In the induced microstructures, fine structures with interperpendicular orientations have been observed under the irradiation of a few pulses. Under the irradiation of the multipulse femtosecond vector field, differently from on the dielectric and semiconductor surfaces, the induced microstructures on the metallic copper surface exhibit an anisotropic extending feature dependent on the polarization distribution of the vector field. The physics behind this unique feature are the anisotropic excitation and propagation of surface plasmons, caused by the coupling of the subsequent irradiation pulses with the existing microstructure.

We have fabricated the complicated two-dimensional subwave-length microstructures induced by the femtosecond vector light fields on silicon. The fabricated microstructures have the interval between two ripples in microstructures to be around 670-690 nm and the depth of the grooves to be about 300 nm when the pulse fluence of 0.26 J/cm2 is slightly higher than the ablated threshold of 0.2 J/cm2 for silicon under the irradiation of 100 pulses. The ripples are always perpendicular to the direction of the locally linear polarization. The designable spatial structure of polarization of the femtosecond vector light field can be used to manipulate the fabricated microstructure.

In this note, relationships among the components, structure distribution and easy magnetization direction, structure of magnetic domain of nano-magnetic material in the major mature lateral radula teeth of chiton A. rubrolinestus Lischke are probed by using the high resolution transmission electron microscope (HRTEM), the scanning electron microscope (SEM), the magnetic force microscope (MFM) and the super-conducting quantum interference device (SQUID) magnetometer from the point of view of magnetism to provide a basis for comprehending biologic function of the magnetic radula.