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Desirable catalysts possessing the ability to selectively break C–H bond and controllably catalyze C–C bond formation are highly demanded for the nonoxidative coupling of methane (NOCM). Herein, a series of Pt-Cu alloy catalysts including Pt1©Cu(111), Pt2©Cu(111) and Pt3©Cu(111) are deliberately designed and systematically studied for NOCM. Density functional theory calculations reveal that the Pt1, Pt2, and Pt3sites on Cu(111) can selectively break the C–H bond to generate CH3, CH2, and CH species, respectively. However, direct coupling of corresponding CHx(x= 3, 2, 1) to form C2H6, C2H4, and C2H2are favorable on Pt3, Pt1, and Pt2sites on Cu(111), respectively. The different reactivity trends of the three Pt sites mainly originate from the varying bonding abilities of CHxspecies at the Pt sites. Microkinetic modeling manifests that the Pt1©Cu(111) is the most active for methane dissociation (TOF = 2.98 s–1at 1000 K) and can selectively convert methane into ethylene with the highest selectivity up to 96.2% at 750 K. Moreover, Pt1©Cu(111) also shows superb stability under reaction conditions. Overall, our studies not only provide a comprehensive understanding of the reaction mechanism of NOCM on Pt single-atom sites (SASs) and Pt single-cluster sites (SCSs) but also predict that Pt SASs are advantageous over Pt SCSs for NOCM.

Tungsten carbide (WC) reinforced Fe-matrix surface composites were prepared by in-situ synthesis between tungsten plate and graphite in grey cast iron. The microstructure, fracture toughness, and fracture of the WC layer were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD) and the Vickers indentation technique, respectively. The results revealed that heat treated at 1125°C for 135min in argon atmosphere the main phase was WC with a bit of α-Fe. The fracture toughness (KIC) of the WC layer calculated using the Niihara’s equation, was 5.21 MPa·m1/2. Fractographic observations revealed that cracks propagated along the grain boundary under 2 kg loads. Moreover, both the WC particles and the interface between the WC layer and the matrix had a strong bonding strength.

The vanadium carbide (V8C7) coating was fabricated by in situ reaction which used gray cast iron and vanadium plate as raw materials providing carbon and vanadium sources, respectively. The microstructure, phases, and adhesion strength of V8C7 coating were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD) and a single scratch test. The XRD results showed that the coating consisted of V8C7 and α-Fe, with the peaks of (222), (400), (440), (622) and (444) of V8C7 phase were confirmed. Moreover, the average diameter (D) of the V8C7 particles in the range of 432~582nm was calculated on the basis of the Scherrer and Halder-Wagner equations. The critical load of interface between V8C7 and substrate was 98.3 N, which implied that the interface of V8C7 coating /substrate had excellent adhesion strength.

Ceramic particles (such as VC, NbC, TiC, and WC), which exhibit high hardness and thermal stability, can be used for in situ fabrication of carbide-reinforced iron matrix composites with high macro-hardness and toughness. In this study, we describe a novel in situ process comprising infiltration casting and heat treatment to form carbide-reinforced iron matrix composites with hard ceramic particles. Our proposed approach was used to integrate different alloy wires, which can easily form carbides, into the metal matrix and cast a known amount of carbon, such as gray cast iron, ductile cast iron, or ordinary white cast iron, to form alloy-reinforced iron matrix composites. Thermal treatment of the resulting composites allowed the alloy elements of the wire to react with carbon in the matrix to form evenly distributed carbide particles. This approach can be applied to a wide range of materials with different morphologies for fabricating composites, machining tools, and wear-resistant components.

Ceramic particles with high hardness and thermal stability can be used to fabricate in situ carbide particulate-reinforced iron-matrix surface composites with high macro-hardness while retaining high toughness. This paper describes a general process by which in situ carbide particulate-reinforced iron-matrix surface composites with hard ceramic particles are readily formed by a novel in situ synthesis process that combines an infiltration casting process with subsequent heat treatment. The basis of our approach is integrating selected plates of different alloys that can form carbide easily into a metal matrix with a certain amount of carbon such as gray or ductile cast iron by casting to form alloy plates reinforced iron-matrix surface composites. Subsequent thermal treatment of resulting composites leads to alloy elements of plate reacting to the carbon in the matrix to form carbide particles. This approach is applicable to a wide range of materials and morphologies, and can be used in composites and machining tools, as well as in the wear-resistant component industry.

Tantalum carbide (TaC) gradient composites were fabricated via in-situ fabrication method from the tantalum plate and gray cast iron. The morphology, phase constituents, micro-hardness, and relative abrasion resistance of the composites were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-hardness tester and abrasive wear testing machine. The surface layer, which was ~160μm thick, was dense ceramic layer composed by ~90% submicron TaC particulates. The highest micro-hardness value of the dense ceramic layer was 13.84 GPa. In the sub-layer, the gradient distribution of TaC particulates reflected in the volume fraction decreased from 90% to 0%. While the micro-hardness value decreased from 10.81 GPa to 4.10 GPa. The metallurgical combination of the interface between the composites and matrix was perfect. The wear resistance of TaC reinforced iron matrix surface gradient composites increased significantly.

Tantalum carbide (TaC) ceramic coating was produced on grey cast iron by the combined process of casting and heat treatment. The microstructure, micro-hardness, and fracture toughness of the TaC ceramic coating were investigated by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and indentation technique. The results show that TaC ceramic coating can be divided into two apparent regions, and the density of products gradually decrease from the surface to the matrix. The main phases of the ceramic coating are only TaC, α-Fe, and Fe3C. TEM examination revealed a nanostructure ceramic, in which 200~300 nm TaC grains are cemented by iron binder. The nanoindentation hardness of TaC ceramic coating vary in the range of 14~21 GPa. A close examination of the indentation crack paths of TaC samples revealed that the TaC ceramic coating have extensive crack deflection with a great amount of intergranular fracture.

The niobium carbide (NbC) coating on gray cast iron has been produced by in situ which combined infiltration casting and heat treatment. The microstructural observations of the coating have been obtained by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). And the growth mechanism of NbC grain was studied. The results show that the mechanism is orientation connection which means two particles of the same lattice orientation will be directly connected together and oriented attachment growth. Fine NbC grain can improve the nanohardness value of the coating with 23 GPa, meanwhile, it increase the elastic modulus with the value of 493.7 GPa.

Micro-nanostructure tantalum carbide (TaC) ceramic was prepared on grey cast iron matrix by the combined process of casting and heat treatment. The theoretical foundation of the nanoindentation technique was introduced in detail, and hardness/modular–displacement curve was received from continuous stiffness measurement (CSM). The results show that, elastic modulus (E) and hardness (H) variation with impression depth depend on size effect and matrix effect. There is no impression pile up effecting on hardness value. It was iron (Fe) existing in micro-nanostructure TaC ceramic during heat treatment , which is the main reason of improving creep property of the TaC ceramic. Study on micro-nanostructure TaC ceramic with high hardness, high elastic modulus and good creep property is meaningful to the application in the area of engineering.

This paper describes a wire composite method which consists of the use of a cast-penetrated-heat treatment process to elaborate cast iron and titanium silk. After 12 h at 1138 °C heat preservation and oven cooling, the cast iron matrix in situ generated a titanium carbide particle beam that reinforced the iron matrix composites as a whole. By XRD, the SEM (EDS) on the overall composite material of the macro and micro structure and composition distribution were studied. The results showed that the titanium was fully reflected and it generated fascicles in the titanium carbide hard phase of particles and uniform distribution. Analysis of single wire on the composition and morphology observation found that the titanium carbide particle beam presents three characteristics: uniform dispersion, long strips, and an aggregation phase. The ML-100 abrasive wearing-testing machine, with two bodies of titanium carbide, reinforced iron matrix composites overall the wearing experiment that was carried out: the result shows that its wearing resistance is about 4.2 times greater than the cast iron standard sample.

This article uses the cast-penetrated-heat treatment process produce V8C7 particle on the surface of iron base composite material, and analyze its organizing appearance using methods such as XRD, SEM, measured its hardness with micro hardness tester of type TUKON2100, operate wear test under different load with wear test machine of ML-100. Results show that the surface of the particle reinforced iron matrix V8C7 composite sample maximum microhardness is 2333 HV0.05. At room temperature, when the load is 15N, its average abrasive resistance is about 13 times that of it of grey cast iron, which improves the wear resistance of the iron substrate to a great extent.

This paper prepared Cu-ZrO2 composite by a modified internal oxidation in order to improve the high temperature strength of resistance Spot-welding electrode. The results showed that with the increasing of the cold deformation, Hardness increased while electrical conductivity decreases. Hardness reached 100HV and electrical conductivity was up to 86%IACS after cold drawn in 56%. With the increasing of annealing temperature and annealing time, Hardness of the composite decreased more slowly compared with the conventional Cu-Cr-Zr alloy and was higher than that of the Cu-Cr-Zr alloy after annealed above 700°C for 2h and at 600°C for 5h , which was attributed to the dispersion strengthening effect of the Zirconia particles. Thus, the Cu-ZrO2 composite has good high-temperature stability and can be used for the electrode

Bi2WO6 doped with iodine ions were synthesized using hydrothermal method and their photocatalytic activities to degrade Rhodamine B (RhB) under visible-light was investigated. The successful incorporation of I ions in Bi2WO6 was proved by XRD and XPS. UV-vis absorption spectra results show that I ion was successfully doped into Bi2WO6 and a red shift for I-doped Bi2WO6 appeared when compared to pure Bi2WO6. The photocatalytic activities of the photocatalysts were evaluated by the decolorization of RhB under visible-light irradiation. The results showed that the photocatalytic activity of I-doped Bi2WO6 was much higher than the undoped Bi2WO6.

Porous peanut-like Sm-doped BiVO4 sub-microstructures were synthesized via a hydrothermal process with bismuth nitrate, ammonium metavanadate and Sm (NO3)3 as raw materials. The crystal structures, morphologies, and optical properties of the as-prepared samples were characterized by X-ray powder diffraction, transmission electron microscope, scanning electron microscopy, and UV-visible absorption spectra. Simulated solar light induced photocatalytic degradation of Rhodamine B by porous peanut-like Sm-doped BiVO4 sub-microstructures have been investigated, and results show the 2% Sm-doped BiVO4 porous sub-microstructures with higher photocatalytic activity than other samples.

Nanocrystalline TiO2 powders were obtained at a low temperature between 50 and 80 oC by a hydrolysis of TiCl4 in a mixed solution of distilled water and alcohol. The as-synthesized TiO2 powders were characterized by X-ray diffraction analysis, transmission electron microscopy, and UVvisible absorption spectroscopy. Effects of the reaction temperature and the NH4F concentration on the formation of the nanocrystalline TiO2 powders were investigated. Results indicate that the reaction temperature greatly affects the particle size of the as-synthesized samples, and the NH4F concentration has a great effect on the phase structure of the as-synthesized samples. In addition, the photocatalytic activities of the as-synthesized samples for rhodamine B were also measured, and it is found that the sample synthesized from the NH4F concentration of 30 mM exhibits a higher photocatalytic activity than the P25 powder due to a high surface area and a pure anatase phase.

Hollow BiVO4 microspheres composed of nanosized particles were successfully prepared via a simple hydrothermal reaction route at 170C for 12 h. The crystal structures, morphologies, and optical properties of the as-prepared samples were characterized by X-ray powder diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM) and UV-visible absorption spectra (UV-vis). Simulated Sun-light induced photocatalytic degradation of Rhodamine B by hollow BiVO4 microspheres has been investigated, and the results show the hollow structures with excellent photocatalytic activity.

In-situ production of (Fe,Cr)7C3 particulate bundles-reinforced iron matrix composites were prepared by infiltration casting between Cr wires and white cast iron at 1200℃ plus subsequent heat treatment. The composites prepared under different heat treatment time were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), macrohardness test and pin-on-disc wear resistance test. The results show that the composite is mainly consist of (Fe,Cr)7C3 carbides and γ-Fe. The area of the particulate bundles gradually increases with the increase of heat treatment time, the microstructure evolved from eutectic to hypoeutectic, and the morphologies of the reinforcements present chrysanthemum-shaped, granular and intercrystalline eutectics, respectively. The (Fe,Cr)7C3 particulate bundles reinforced composite has high macrohardness and excellent wear resistance under dry sliding wear testing conditons.

In-situ production of (Fe,Cr)7C3 particulate bundles -reinforced iron matrix composite was prepared by infiltration casting between Cr wires and white cast iron at 1200℃ plus subsequent heat treatment. The composites under different heat treatment times were comparatively characterized by scanning electron microscopy (SEM) and pin-on-disc wear resistance tests. The results show that the area of the particle bundles gradually increases with the heat treatment time increasing, and the chemical compositions change from eutectic to hypoeutectic, the morphologies of the reinforcements present chrysanthemum-shaped, granular and intercrystalline eutectics. Under 5 N loads, the composites appear excellent wear resistance, which is 36 times for the reference sample.

An in-situ synthesis process combining an infiltration casting with a following heating treatment was applied to fabricate special titanium carbide (TiC) particles-reinforced iron matrix surface gradient composites in this article. The microstructure and wear-resistance of the titanium carbide particle reinforced iron matrix surface gradient composites were researched by using differential scanning calorimetry, X-ray diffraction, scanning electron microscopy and abrasive wear testing. The results showed that two materials had been reacted completely between the titanium plate and gray cast iron, and the titanium carbide particles distributed in the matrix with the thickness of 266.7 μm reaction layer. The average size of titanium carbide between titanium plate and iron matrix was about 1-2μm. Under the same condition, the wear mechanism of titanium carbide particles-reinforced iron matrix surface gradient composites appeared as: micro-ploughing, micro-cutting and broken titanium carbide.

The Ni-SiC nano-composite coatings were prepared on the ring of stainless steel by using of high frequency pulse electroplating. Orthogonal experiment was used to study optimal dosage of the dispersant. The effect of some factors, such as current density, pH value, temperature , addition agent and so on, were studied. The characterization of Ni-SiC nano-composite coatings were studied by wear test. The effect of pulse frequency and the SiC concentration in the electrolyte on the wear resistance of Ni-SiC nano-composite coatings were studied. The morphology of the nano-composite coatings in wear test before and after were analyzed by SEM and the metaloscope photographs. The results show that Ni-SiC nano-composite coatings of high frequency pulse electroforming have better performance of wear resistance.

Nano- and micro-scaled LiFePO4 was synthesized by hydrothermal synthesis method using disodium ethylenediamine tetraacetate (Na2EDTA)-assisted to avoid the Fe(II) ions from oxidation and control the growth of the crystal. The as-synthesized samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), The SEM showed that the pH value of the synthesis solution played a key role in the formation of the final products with different morphologies. Charge–discharge cycling performances were used to characterize its electrochemical properties. The results indicated that the nano-sized LiFePO4 presents enhanced discharge capacities (148 mAhg−1 at 0.1C-rate) and stable cycling performance. This study offered a simple method to design and synthesis nano-sized cathode materials for lithium-ion batteries.

The method of infiltration casting plus heat treatment process employing chromium wires and cast iron applied to in-situ synthesized (Fe,Cr)7C3 particulates bundle reinforced iron matrix composites. The phase analysis, microstructure, microhardness and wear-resistance of composite were observed and measured. The results show that it is possible to fabricate (Fe,Cr)7C3 particulates bundle reinforced iron matrix composite produced by this technology, and a special structure which called particulates bundle was fabricated. (Fe,Cr)7C3 particulates bundle were distributed in the forms of granular, lath-shaped and hexagon-shaped in the particulates bundle. The macrohardness of particulates bundle was 52 HRC, and the relative wear resistance of the composites is 2.3—23 times higher than that of the cast iron.

Niobium carbide (NbC) particulates -reinforced iron matrix composites were prepared by in- situ fabrication method combining an infiltration casting with a subsequent heat treatment. The microstructure and wear-resistance of NbC particulate-reinforced iron matrix composites were studied using scanning electron microscopy, X-ray diffraction, and wear testing. The results indicate that at 1172 °C for 3 hours NbC particulate-reinforced iron matrix composites were fabricated, and the size of NbC reinforcement was 0.3–3.5 μm. The relative wear resistance of the composites was 5.4 times higher than that of gray cast iron under a 20 N load. This was achieved at 22 % NbC volume fraction. Wear of the composites manifests as grooves, broken carbide particulates and some micro-cracks.

An in-situ synthesis process combining an infiltration casting with a subsequent heat treatment was applied to fabricate special tungsten carbide (WC) bundles-reinforced iron matrix composites in this work. The microstructure and wear-resistance of the tungsten carbide bundles reinforced iron matrix composites were studied by using scanning electron microscopy, X-ray diffraction and wear tester. Results showed that the tungsten carbide bundles distributed in the matrix with the center-to-center spacing 2.2 mm, and the diameter of each tungsten carbide bundle is about 1 mm. Most of the tungsten carbides agglomerated, but still there were tungsten carbide particles and the size of tungsten carbide particle was about 10—15 μm. The weight loss of the tungsten carbides bundle reinforced iron matrix composites increased with the increase of the loads and the weight loss of the composites is much less than those of the gray cast iron under the same condition. The wear mechanism of tungsten carbide bundles-reinforced iron matrix composites appears as: micro-cutting, micro-ploughing, broken tungsten carbide and broken particles re-embedded in the matrix.

Eu3+ -doped GdVO4 powders have been synthesized via a novel hydrothermal method using commercially available Gd2O3, NH4VO3 and Eu2O3 as the reacting precursors. The influences of several important parameters, such as hydrothermal temperature, reaction time and pH value, of the experiment were investigated. The obtained samples were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), and photo-luminescence spectroscopy (PL). The experimental results showed that the optimal reaction condition was processed at 180˚C for 12 h and adjusted pH value to 4. The morphology of products was uniform pseudo-octahedron with a little conglomeration. All the phosphors exhibit the characteristic dominant red emission of Eu3+ ion (5D0 → 7F2) at 618nm.

Cu-coated Ti3SiC2 powder was fabricated by electroless copper plating method from CuSO4 using poisonless ascorbic acid (C6H6O4(OH)2) as reducing agent. Sensibilization and activation on Ti3SiC2 powder surface was performed by Sn-Ag catalyst system. Surfactants lauryl sodium sulfate (SDS) and Polysorbate 80 (Tween-80) were used as modifiers to control copper particle sizes and shapes. It is found that good pretreatment and activation can obtain fully-formed copper coating. The optimal copper deposition rate can reach to 2.053 g.dm-2.h-1 at 80℃ . The best coating effect can be obtained in the samples modifying with 12g/L SDS+8ml/L Tween-80.

In the paper, tungsten carbide (WC) particles can be in-situ synthesized by applying electromagnetic field to the system consisting of tungsten wires and gray cast iron melt at 1573 K. The microstructures and wear-resistant properties of composites reinforced by both WC particles and the residual tungsten wires were investigated by XRD, SEM, EDS, micro-hardness and pin-on-disc wear measurements. The results show that, with enhancing frequencies of electromagnetic field from 0 to 5 KHz, the amounts of in-situ WC particles increased and of the residual tungsten wires gradually decreased until tungsten wires completely reacted. Due to the higher hardness of in-situ WCp(2100-2231HV0.1) and the strong interfacial bonding, the composites displayed an excellent wear-resistant properties. When the frequency was 5 kHz, the wear loss for the composite fabricated was optimal and 2.69 times lower than that of reference samples.

Li2MSiO4(M=Mn, Co, Ni) is a potential high capacity cathode material because of its outstanding properties that exchange of two electrons per transition metal atom is possible and the theoretical capacity of Li2MSiO4 can reach as high as 330 mAhg-1. In this family, the cathode performance of Li2MnSiO4 synthesized by solution route has been published recently. However, it seems that the cycle life of Li2MnSiO4 fell short of our expectation. In this work, the Li2Mn0.7Fe0.3SiO4 cathode material was synthesized by traditional solid-state reaction method. The prepared powder was consisted of majority of Li2Mn0.7Fe0.3SiO4 and minor impurities which were examined by XRD. FESEM morphology showed that the products of Li2Mn0.7Fe0.3SiO4 and Li2MnSiO4 have similar particle size (about 50-300 nm). The electrochemical performance of Li2Mn0.7Fe0.3SiO4, especially for reversible capacity and cycle life, exhibited better than those of Li2MnSiO4.

The present research describes a simple low-temperature synthesis route of fabricating porous YVO4:Sm nanoplates via a chemical co-precipitation method using commercially available Y2O3, NH4VO3, Sm2O3 and ethylene glycol as the reacting precursors. The as-synthesized YVO4:Sm was thermally treated at 300°C and 600°C for 2 h which is much lower than that of the conventional preparation methods. The obtained samples were characterized by FTIR, XRD, TEM and PL. The photoluminescence measurement revealed that the luminescence intensity was significantly increased with increasing annealing temperature.

To investigate the possibility and reaction route of fabrication high purity Ti3SiC2 powders using coarse reactants by a relatively simpler method, Ti/Si/TiC mixtures (74μm in average size) added proper amount of aluminum were heated in vacuum sintering furnace with different sintering scheme. The effects of Al addition and temperature on the purity of resultant Ti3SiC2 powder were also examined. The results showed that over 99wt.% content Ti3SiC2 powders could be obtained at optimal temperature 1410°C-1420°C holding 90-120min with 0.10-0.20 Al addition (molar ratio). XRD, SEM and EDS results indicated that Ti5Si3 and TiCx were the main intermediate phases which redounded to synthesize Ti3SiC2 powder subsequently.

It has been well known that Hadfield steel behaviors excellent wear resistance under high impact energy. Up to now there exist many theories to explain the wear mechanism of Hadfield steel. In this research subsurface microstructure evolution process of Hadfield steel was investigated after high energy impact experiments. It was shown from high resolution electron microscope (HRTEM) examination of subsurface microstructure that nanocrystallized austenite grains have been formed in the procedure of the reaction and rearrangement of high density dislocations under the heavy plastic deformation, sub-grains as a transitional structure and, finally, the formation of nano austenite grains. On the other side, the interactions of twins and stack faults or dislocations and stack faults make austenite crystals transform to amorphous solid. With increasing impact cycles the sizes of nano-grains were decreased and the amorphous volumes were increased further. A large amount of nano-sized grains embedded in bulk amorphous matrix were fully developed, which will dominate the wear of the steel. In the subsurface no martensitic transformation was observed.

Under high impact energy, nano-structured surface layers of Hadfield steel and annealed AISI 1045 steel were investigated in the present paper. It has been observed that a so-called “black layer” for Hadfield steel and “white layer” for AISI 1045 steel has been formed, respectively. That definitely will give rise to a change of wear mechanism. The wear tests showed that the wear weight loss curve of Hadfield steel will be bent down after some critical impact numbers. The wear curve of the AISI 1045 steel, however, shows a step-like characteristic with increasing impact numbers. It can be found from microstructural examination that high density twin bands of subsurface for Hadfield steel were produced, which have good plastic deformation coordination with bulk material. Cracks are usually initiated in the “black layer” underneath 12 µm in depth, and the worn debris sizes were also observed in nano-scale. Nano scaled wear controls the whole wear process. For the annealed AISI 1045 steel, cracks are mainly initiated between the interface of the “white layer” and sub-surface deformation layer. Debris is in micron-scale and spalled in the flake-like style. The wear weight loss is, therefore, greater than that of Hadfield steel. The result showed from the wear tests of Hadfield steel and AISI 1045 steel that nanocrystalized process of subsurface becomes one of control factors to affect wear losses and wear mechanism under high impact energy.