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Besides cast-rolling speed and casting temperature， the melt pressure in the cast-rolling zone is also an important factor affecting the process stability and interfacial bonding strength of horizontal two-roll cast Ti/Al composite plate. In this study， several Ti/Al composite plates were prepared under different melt pressures in the cast-rolling zone by adjusting the liquid level of the melt in the sluice during the cast-rolling composite process. The microstructure and interfacial bonding properties of the composite plates were characterized by metallography， scanning electron microscopy， microhardness， tensile test and T-type peeling test at room temperature. Results show that when the melt pressure is relatively high， composite plate with full filling， good plate shape and high bonding strength can be produced successfully. However， excessively high melt pressure will affect the stability of the cast-rolling composite process. When the melt pressure is too low， the transverse flow capacity of the melt decreases. As a result， the cast-rolling zone cannot be completely filled with the melt， and the defects such as misrun and side penetration occur. At the same time， some micropores and microcracks appear on the Ti/Al interface. Under relatively high melt pressure， the solid/liquid contact distance is long. In this condition， the wetting between the strip surface and the melt is more sufficient， the melt is more evenly distributed， and the diffusion between solid and liquid is more sufficient. As a result， the composite plate has high bonding strength， which reaches 20.1 N/mm.

A Ti/Al/Cu clad sheet was fabricated by using horizontal twin-roll casting (HTRC) with the application of pulsed electric field (PEF) and electromagnetic oscillation field (EOF), and the effects of different external fields on interfacial bonding strength were studied. The results show that the external electromagnetic fields have little influence on the stability of HTRC process. With the application of PEF and EOF, the width of diffusion layer at the Ti/Al and Cu/Al interface increases obviously. The interface bonding strength is significantly improved. When the EOF is applied, the electromagnetic volumetric force is generated in the liquid cavity of cast-rolling zone. Under the action of the electromagnetic volume force, aluminum melt oscillates repeatedly, which scours the surface of the strips and makes the newly formed crystal nuclei fall off the surface of strips. In addition, the oscillation effect reduces the temperature gradient at the contact area between strip and melt and slows down the solidification process, thus prolonging the contact time between aluminum and strips. All of these effects make the melt spread more sufficient on the surface of strips and promote the interdi-ffusion between atoms.As a result, more metallurgical bonding regions are formed and enhanced.

In order to investigate the distribution of temperature field in directionally solidified DZ4125 columnar superalloy, and to study the effects of different withdrawl rates on the changes of temperature gradient and mushy zone, the directional solidification processes with withdrawal rates of 3, 5 and 7 mm/min were simulated by ProCAST software. The results show that when the test rod is located in the heating zone, the isotherm is inclined distribution with low outside and high inside. And when the test rod is located in the cooling zone, the isotherm is inclined distribution with high outside and low inside. With the increase of withdrawal rate, the temperature gradient decreases gradually. The shape of the mushy zone depends on the withdrawal rate and the distance from the water-cooled plate. When the withdrawl rate is 5 mm/min, the horizontal state of the solidification front is maintained for a longest time. On this basis, the precision casting experiment of directional solidification test rod is carried out, and the relationship between the shape of liquidus and grain structure is found for castings withdrawn at 3 and 7 mm/min. It is found that when the liquidus is concave and convex, the grain grows towards the center and the surface of the test rod, and the horizontal liquidus can promote the grain growth along the axis of the test rod.

Advanced oxidation process based on sulfate radical (SO4-·) is recognized as one of the effective methods to degrade organic wastewater. In recent years, as an economical and readily available carbon containing material, biochar has been gradually applied in the advanced oxidation field. Biochar and its composite activated persulfate have become a promising system for organic pollutants degradation. The latest research progress of different typical biochar-based catalysts for persulfate activation was analyzed, including pristine biochar, transition metal loaded biochar, non-metallic doping biochar, and metallic and non-metallic co-doping biochar. In addition, the synthesis methods and physicochemical properties were summarized. Furthermore, the activation performance and mechanism of biochar-based catalysts for persulfate and the degradation mechanism of organic pollutants were discussed, respectively. Finally, based on the current research progress, from the perspectives of different biomass sources, metallic and non-metallic co-modified biochar technology and the dynamic change of ecotoxicity in the degradation process, relevant discussions and future suggestions for biochar and its composites were put forward in terms of degradation mechanism exploration, potential catalyst development and practical catalytic system application.

In order to simulate the structure and function of human arm and wrist joint, a 3-DOF(degree-of-freedom) cable-driven humanoid wrist is put forward, which is different from the traditional bionic joint, its function is achieved by a ball joint which connects the moving base platform and the base. However, the introduction of cables increases the difficulty in modeling and control. Firstly, ignoring the gravity property of the cable, the standard dynamics equation of the humanoid-wrist joint is built by using Lagrange method. At the same time, taking into account the redundant actuation and single-direction force for the cables, the cable tension distribution optimization model is established, and the cable tension distribution is obtained by genetic algorithm. Secondly, aiming at the influence of the cable mass, a more accurate dynamics model is established by considering catenary. Finally, the two models are simulated and the simulation results are compared.

Quantitative microstructural evolution and the corresponding microhardness of electrodeposited nanostructured nickel sheet during cold rolling deformation are investigated by x-ray diffraction, transmission electron microscopy and Vicker’s microhardness testing. Particularly, to investigate the effect of stress states on deformation behavior, two series of gradient nanostructured nickel with symmetric structures and the homogeneous counterparts with three levels of grain size are compared based on macro-statistical data. In such hierarchical sandwich-like gradient samples, the layers with larger grain size, as the soft phase, indeed sustain more deformation. Deformation-induced grain rotation changes are observed in the center layers with a relatively larger grain size, accompanied by an obvious decrease in microhardness. According to the quantitative microstructural parameters including the grain size, dislocation density and stacking fault probability before and after deformation, evaluation based on Hall-Petch and Bailey-Hirsch relationships indicates the transition from strain hardening to softening can be attributed to grain orientation change.

This review focuses on grain growth behaviors and the underlying mechanisms of bulk electrodeposited nanocrystalline nickel and nickel-iron alloys. Effects of some important factors on grain growth are described. During thermal-induced grain growth process, grain boundary migration plays a key role. For similar thermal conditions, due to grain boundary mobility with solute drag, limited grain growth occurs in nanocrystalline alloys, as compared to pure metals. Nonetheless, in the case of stress-induced grain growth process, there are a variety of mechanisms in samples having various deformation histories. As an example the grain growth of nanocrystalline nickel and Ni-20%Fe alloy with nearly the same grain-size distribution and average grain size is compared in this paper. Thermal analysis indicates nanocrystalline nickel is much more prone to rapid grain growth than nanocrystalline Ni-20%Fe alloy. Nevertheless, grain growth of nanocrystalline Ni-20%Fe is found to be more pronounced than nanocrystalline nickel during rolling deformation.

In this study, oxide dispersion strengthened (ODS) ferritic steels with nominal composition of Fe–14Cr–2W–0.35Y2O3 (14Cr non Zr-ODS) and Fe–14Cr–2W–0.3Zr–0.35Y2O3 (14Cr–Zr-ODS) were fabricated by mechanical alloying (MA) and hot isostatic pressing (HIP) technique to explore the impact of Zr addition on the microstructure and mechanical properties of 14Cr-ODS steels. Microstructure characterization revealed that Zr addition led to the formation of finer oxides, which was identified as Y4Zr3O12, with denser dispersion in the matrix. The ultimate tensile strength (UTS) of the non Zr-ODS steel is about 1201 MPa, but UTS of the Zr-ODS steel increases to1372 MPa, indicating the enhancement of mechanical properties by Zr addition.

In this study, we investigated the effects of the quenching and tempering temperatures on the microstructure and mechanical properties of low-alloy wear-resistant steel NM450. The quenching temperatures were 870 °C–1200 °C, and held for 36 min. After quenching with 910 °C, the tempering temperatures were 200 °C–600 °C for 60 min. The results showed that as the quenching temperature increasing, the original austenite grain size increased and the proportion of high-angle grain boundaries gradually decreased, which was detrimental to the toughness of the steel. The inter-lamellar-retained austenite remaining in the martensite lath during quenching satisfied the Kurdjumov-Saches relationship with martensite. At the tempering temperatures lower than 250 °C, carbon atoms precipitated in the form of fine carbides, which improved the yield strength of the steel. With the increasing of the tempering temperature, the activity of the carbon atoms increased, the size of the carbides increased, the effects of solid solution strengthening and precipitation strengthening weakened, so the tensile and yield strengths of the steel decreased. The low-alloy wear-resistant steel tempering at 250 °C exhibited the satisfactory combination of properties. The quasi-cleavage fracture occurred mainly over the tempering temperature range of 300 °C–400 °C, and the fracture mechanism turned into ductile fracture when the tempering temperature was higher than 500 °C.

The reaction of N-(pyridine-2-ylmethyl)pyrazine-2-carboxamide (HL) and copper(II) sulfate leads to the formation of a new copper complex, [Cu2L2ox(SO4)(H2O)4](H2O)4(1), in which the deprotonated amide L-ligand was oxidized to a imide Lox-exposed to the air in the presence of the Cu ion. The X-ray crystal analysis reveals that it consists of two mononuclear copper unit with different coordination modes, multiple O-H…O hydrogen bonding between water molecules or water and sulfate O atom to form 3D networks. CCDC: 2088935,1.

The reaction of N-(pyridine-2-ylmethyl)pyrazine-2-carboxamide (HL), 4, 4′-bipyridine(4, 4′-bipy) and copper(II) perchlorate leads to the formation of a new copper complex, [CuL(4, 4′bipy)(H2O)2](H2O)(ClO4) (1), The X-ray crystal analysis reveals that it is a mononuclear complex. CCDC: 1487818, 1.