Four polygonal ferrite/acicular ferrite (PF/AF) dual-phase steels with different volume fractions of polygonal ferrite were processed by heat treatment process. The effect of soft phase (polygonal ferrite) ratio on the effective grain size and geometrically necessary dislocation density (GND) was analyzed by electron backscattered diffraction (EBSD). While the relationship between stress ratio and strain hardening exponent (n), as well as the tensile deformation behavior and the relevant strain hardening mechanism of dual-phase pipeline steels of PF/AF dual-phase steels with different PF volume fractions were assessed by means of empirical formulas of the so called Hollomon analysis and modified C-J analysis. The results show that the strain hardening ability of PF/AF dual-phase steel is almost independent of stress ratio, while the strain hardening index has a specific linear relationship with the uniform elongation. With the increase of volume fraction of polygonal ferrite, the necking point moves backward and the strain hardening behavior changes from two-stage to three-stage process. The change of volume fraction of polygonal ferrite has a significant effect on the strain hardening ability of the first and second stages.

Electrical contact Cu-W composites with three different micro-directional structure was designed, and characterized in terms of different shape factors. Then the influence of shape factors on their electrical conductivity and mechanical properties was investigated. Based on effective medium equation (GEM), conductive channel theory and simulation calculation, the current density distribution, and its relationship with the shape factor of composites with different skeleton structures were acquired. The results show that the closer the shape factor F to 1 is, the easier the formation of the cluster-like conductive channels are, thereby the better the conductivity is. The deformation characteristics of different composite materials were simulated and analyzed according to the Mises yield criterion, while the relationship between mechanical properties and shape factor was proposed, that is, with the increase of roundness of shape factor, the stability of force conduction element was improved. The larger the roundness of the shape factor is, the less deformation of the force conduction element is and the better the mechanical properties are. In a word, the comprehensive properties of the electrical contact Cu-W composite material can be further optimized by adjusting appropriately its conductivity and mechanical properties.

Composite of carbon fiber (Cf) with Al-film (Cf/Al) was constructed by magnetron sputtering with mesophase pitch-based carbon fibers of different graphitization degrees as matrix and Al-plate as sputtering target. Then, the microstructure evolution of Cf /Al interface of the prepared composites was investigated, and the damage mechanism of Cf /Al interface was revealed in comparison to that prepared with polyacrylonitrile carbon fiber. The results show: With the increase of graphitization temperature, the size, the degree of orientation and graphitization of graphite micro-crystallites in mesophase asphalt based carbon fiber increased, whilst both of the reaction degree of Cf /Al interface and the damage of carbon fiber reduced. The damage of Cf /Al interface of the composites prepared with Cf of different graphitization degrees depends on the number of initial defects and the propagation of subsequent cracks in the carbon fiber. The graphitization treatment at 2400℃ and 2700℃ could facilitate the crack propagation through graphite micro-lamellas located in between mesophase asphalt-based carbon fibers, however after removing the Al-coating, the fiber damage was 5.19% and 3.70% higher than that of polyacrylonitrile carbon fiber respectively. After graphitization at 3000℃, the mesophase bituminous carbon fiber with higher chemical inertia could reduce the number of defects generated by interfacial reaction, whilst, after removing the Al-coating, the damage of the fiber was 1.85% lower than that of polyacrylonitrile carbon fiber.

Ag-modified SnSe nanotubes (Ag/SnSe NTs) were fabricated by light irradiation assissted deposition process, therewith Ag nanoparticles were deposited on the surface of SnSe NTs at room temperature. The morphology, chemical composition and crystal structure of the prepared Ag/SnSe NTs were characterized by SEM, EDS, TEM and XRD. The results show that the average diameter of SnSe NTs covered with Ag nanoparticles is approximately 100~200 nm. In addition, the infrared detector based on Ag/SnSe NTs (IRPD) was assembled with Ag/SnSe NTs spin-coated on the conductive surface of FTO as the working electrode and the Pt electrode as the counter electrode. Afterwards, the infrared detection performance of Ag/SnSe NTs IRPD was further investigated by adopting infrared light of 830 nm as the simulated light source. Compared with the SnSe NTs IRPD, the maximum photocurrent density of Ag/SnSe NTs IRPD achieves 120 nA/cm², simultaneously the rise time and decay time are declined to 0.109 s and 0.086 s, respectively, demonstrating the characteristics of good stability and repeatability.

The luminescence properties of GO were investigated by means of photoluminescence spectra and absorption spectra. It follows that the luminescence of GO originates from sp²C clusters in lamellar. Sp²C clusters are surrounded by high barrier oxidation functional groups (sp³C), forming a multi-quantum well structure. There are sp²C clusters of different sizes in GO, and the band gap is related to the size. The smaller the size, the wider the band gap, so that the luminous coverage is wider and depends on the excitation wavelength. The emission behavior of different local states in GO was investigated by changing the excitation wavelength and temperature. The results show that the thermal activation energy of sp²C clusters excited by 514 nm was 56 MeV higher than that excited by 830 nm. Temperature has little effect on smaller sp²C clusters, because the smaller the size, the stronger the confinement effect and the radiative transition probability of electron hole pair is increased.

SnO₂ nanopoints were in-situ grown on and between Ti₃C₂T_x layers, and the nanostructured SnO₂@Ti₃C₂T_x composites were prepared by ultrasonic adsorption and low temperature heat treatment. SnO₂@Ti₃C₂T_x composites were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM). Results show that SnO₂ nanoparticles are densely distributed between the layers of Ti₃C₂T_x. Ti₃C₂T_xowns outstanding limiting effect and graphite-like structure, it inhibits the volume expansion and agglomeration of SnO₂ and accelerates the transition of lithium ions and electrons. In addition, SnO₂ is embedded between the layers to improve the longitudinal structural stability of Ti₃C₂T_x by preventing the restacking. Therefore, SnO₂@Ti₃C₂T_x shows a synergistic effect between the two components and has good rate and cycle performance as anode of LIBs.

In order to explore the mechanism of the influence of ion irradiation on the microstructure and properties of as-welded and quenched and tempered welds, the welds of Low Activation Martensitic (CLAM) steel were subjected to He ion irradiation at room temperature of 70 keV. Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Continuous Stiffness Measurement (CSM) detection methods were utilized to investigate the changes in microstructure and properties of CLAM steel welds before and after ion irradiation. The results show that the size and number density of black holes on the welds' surface after irradiation increased with the rising irradiation dose; at the irradiation dose of 1×10¹⁷ ions·cm^-2, the sizes of dislocation loops formed in the two welds were 18.97 nm and 15.73 nm respectively and the number densities were 2.24×10²¹ m^-3 and 1.78×10²¹ m^-3 respectively; the irradiation swelling rates caused by helium bubbles were 1.7% and 0.4% respectively; the radiation hardening rate caused by irradiation defects (dislocation loops and helium bubbles) were 49.0% and 29.9%, respectively. However, compared with as-welded weld, the irradiation damage of quenched and tempered weld was relatively weaker after He ion irradiation. To a certain extent, it showed that the anti-irradiation performance of the weld after quenched and tempered was improved.

Welded joints of Q1100 ultra high strength steel were made via gas shielded arc welding with welding heat inputs of 10 kJ/cm and 15 kJ/cm respectively. The microstructure, mechanical properties and local corrosion behavior of welded joints were studied. The results show that the microstructure of weld zone for the two welded joints is mainly acicular ferrite and a small amount of granular bainite. The microstructure is lath bainite for the coarse grain zone, and lath bainite and granular bainite for the fine grain zone of the weld joints. The microstructure of the critical phase transition zone is a mixture of polygonal ferrite, Mayo islets and carbide. The charge transfer resistance of various portions of the two welded joints could be ranked as the following order: base metal > heat affected zone > weld zone. The base metal had the best corrosion resistance, followed by the heat affected zone, and the weld zone had the worst corrosion resistance. During the corrosion process, the weld zone was first corroded as an anode. After a certain time of corrosion, the corrosion position changed, and the anode corrosion area was transferred into the base metal, while the weld zone was protected as a cathode. The welded joint with heat input of 10 kJ/cm has better low temperature toughness and corrosion resistance. The impact energies are 46.5 J and 30.2 J for the weld zone and heat affected zone respectively at -40℃.

Hydrogel of (CMC/AA/CB[8]/BET gel) with controllable mechanical properties was prepared with carboxymethyl cellulose and acrylic acid as raw material, while octagon melon ring and bentonite as double crosslinking agent. The structure and morphology of the prepared gel were characterized by FT-IR and SEM. The mechanical properties, adsorption properties, swelling and adsorption kinetics of the gel were investigated. The results show that CB[8] and BET formed a dense network structure through hydrogen bonding with AA grafted to CMC, which enhanced the mechanical properties of the gel;The swelling of the gel conforms to the quasi-second-order kinetic model and the theory of stress relaxation swelling hemicrystalline polymer; After the gel was soaked in acid, the hydrogen bond between the free H+ in the acid and CB[8] and BET significantly increased the breaking strength of the gel from 0.52 MPa to 3.0 MPa; The gel has a good adsorption effect on methylene blue, which accords with the quasi-second-order kinetic model.

Cu-doped rutile TiO₂ photocatalysts with different concentrations were prepared by sol-gel method at 650℃. The crystal structure, surface morphology, elemental composition and valence state, surface area and optical property of the obtained photocatalysts were characterized by XRD, SEM, TEM, XPS, BET, PL and DRS. The results show that pure TiO₂ is a mixed crystal composed of a small amount of anatase and a large amount of rutile. Cu doping is conducive to the transformation of anatase to rutile, and Cu-doped TiO₂ forms single rutile phase. Cu element exists in the form of +1 and +2 valence coexistence in the sample. Using rhodamine B as the target pollutant and xenon lamp as the UV-visible light source, the photocatalytic activity was investigated. The results show that Cu doping inhibits the photocatalytic activity. The results of optical property show that although Cu doping is beneficial to suppressing the recombination of photogenerated electrons and holes, it reduces the absorption of the photocatalyst in the ultraviolet religion, which leads to the decline of photocatalytic activity.