Nanofibers of palladium(Pd)/polyaniline(PANI) were synthesized via liquid phase chemical oxidation in dark conditions with aniline as monomer, palladium chloride (PdCl₂) as palladium precursor and ammonium persulfate as oxidant. The synthesized nanofibers were characterized by XRD, FESEM, TEM, SAED, HRTEM, FT-IR spectroscopy and UV-visible spectroscopy. Electrochemical performance of ethanol oxidation was also investigated on a glassy carbon electrode modified with Pd/PANI nanofibers. The results show that the length of Pd/PANI nanofibers can reach up to 500 nm with average diameters of 20 nm. Pd nanoparticles with the average diameter of 6 nm can uniformly distribute over the PANI fibers. The electrochemical active surface area (ECSA) of the Pd/PANI/GCE (54.76 m²/g_Pd) is nine times higher than that of commercial Pd/C catalyst (6.08 m²/g_Pd). The value of j_f/j_b of Pd/PANI/GCE is 1.192.

Ni+WC composite cladding was prepared on the surface of 45 ^# steel by vacuum cladding technology. The formation mechanism of nickel-based composite coating was investigated by intermittently sampling. The results show that a Ni-based composite cladding with metallurgical fusion to the matrix and uniform distribution of WC hard particles is obtained on the surface of 45 steel. The entire cladding consists of a 4 mm thick composite layer, a 1 mm thick transition layer, a 20 μm thick diffusion fused zone, and a 250 μm thick diffusion affected zone. The composite layer composes of WC and W-rich multiphase carbide formed after decomposition, surrounded by Ni particles; The main phase constituents of the composite cladding layer include γ-Ni solid solution, Cr₇C₃, Ni_2.9Cr_0.7Fe_0.36, Cr₂₃C₆, Ni₃Fe, Ni₃Si, Ni₃B, W₂C and C. The vacuum cladding process mainly includes the formation of a micro-sintered neck between the particles in the heating stage before the Ni-based alloy particles reach its melting point, and the melting of the Ni-based alloy particles at the beginning stage of its melting point and the third stages of fusion diffusion in the heat preservation stage and position adjustment of the WC particle within micro-area.

The graphene oxide (GO) was firstly synthesized by the Hummer method, and then the nanocomposites of PBT/GO with different GO contents were prepared by melt blending. The mechanical properties of the PBT/GO-nanocomposites were tested. Results show that the tensile strength and impact strength of the nanocomposites increased first and then decreased with the increase of GO content, however the PBT/GO-nanocomposite with 0.5% GO exhibits the best mechanical performance. The PBT/GO nanocomposite with 0.5% GO was selected for further heat-treatment at various temperatures (150^oC, 180^oC and 200^oC) for differnet times (30 min, 60 min and 90 min), then the effect of heat-treating on its structure and properties were investigated. With the increase of heat treatment temperature the tensile strength and impact strength could reach as high as 63.2 MPa and 11.6 kJ/m², which increased by 36.1% and 59.3%, respectively compared with those of untreated ones. With the prolongation of heat treatment time, the tensile strength and impact strength of the composite could reach up to 62.3 MPa and 11.0 kJ/m², which increased by 34.2% and 51.9%, respectively. DSC tests show that with the increasing heat treatment temperature and time the degree of crystallinity of the composites was enhanced by 11.4% and 8.6% respectively, however the heating temperature has much strong influence on the degree of crystallinity rather than holding time. XRD results show that heat treatment did not change the crystallographic structure of the composite. With the increasing heat treatment temperature, the thermal conductivity of the composite was 0.49 W/(m·K) and 0.42 W/(m·K) measured at 50^oC and 100^oC respectively. Correspondingly, which increased by 24.1% and 18.6%, respectively in comparison with those of the non-heat treated ones. With the increasing heat treatment time, the thermal conductivity of the composite could rach up to 0.46 W/(m·K) and 0.37 W/(m·K) at 50^oC and 100^oC, which increased by 14.6% and 5.9% in comparison to those of the non-heat treated ones. Besides, the heat treatment temperature presents much obvious influence on the enhancement of the thermal conductivity of the composite.

The effect of quenching rate on the microstructure and properties of automotive high-strength Al-alloys were investigated by mechanical property testing, electrical conductivity measurement and transmission electron microscopy. The results show that as the quenching rate decreased from 960^oC/s to 1.8^oC/s, the electrical conductivity increased by 5.7% IACS, the hardness reduction rate is 40%, and the reduction rates of tensile strength and yield strength are 24.2% and 56.9%, respectively. The hardness and strength are linearly related to the logarithm of quenching rate. With the decrease of quenching rate, the size and area fraction of quenching precipitates increase significantly, resulting in the decrease of performance. When the quenching rate is 1.8^oC/s, the average size and the area fraction of the quenching precipitate are 465.6 nm×158.2 nm and 42.1%, respectively.

Dynamic compression tests of the as-extruded 6013-T4 Al-alloy were carried out via split Hopkinson pressure bar at room temperature with strain rates ranging from 1×10³ s^-1 to 3×10³ s^-1. The results show that the alloy exhibits obvious strain hardening and positive strain rate sensitivity. The density of the dislocation increases with the increasing strain and strain rate. High strain rate and large strain deformation lead to the pile-up of dislocations. Under the same impact condition, the 0° specimen displays the highest stress level, and the 45° specimen has the lowest one. The Schmid factors for each type of the main texture components were calculated. The max Schmid factors are 0.27 for 0°, 45° and 90° specimens, and 0.49 and 0.41 for {112}<111> texture; they are 0.27, 0.43 and 0.41 for {110}<111> texture. The Schmid factors of 0° specimens are always the smallest, which results in a higher stress level. When the specimens were dynamic compressed under the same strain and strain rate, the dislocation density of 0° specimen is the highest. Therefore, it is necessary to consider the strain rate sensitivity, anisotropic mechanical behavior and microstructure evolution in the material selection and structural design of components subjected impact loads.

The 3D printing medical titanium alloys Ti-6Al-4V and Ti-6Al-4V-5Cu were prepared by selective laser melting technology (SLM), and their antibacterial properties were assessed by plate co-culture method. The in vitro biocompatibility with the mouse embryonic osteogenic precursor cells (MC3T3-E1) of the prepared alloys was systematically investigated by means of methods of CCK8 cell proliferation assay, phalloidin cytoskeleton staining and Annexin-V/PI flow cytometry. The results show that the 3D printing Ti-6Al-4V-5Cu alloy has high antibacterial property and the antibacterial rate against Staphylococcus aureus is 57.03%. The alloy Ti-6Al-4V-5Cu performed well with better in vitro biocompatibility during the three assessments,namely,CCK8 cell proliferation toxicity assay, cytoskeleton phalloidin staining experiment and Annexin-V/PI double labeling flow analysis.

The Co_0.525Fe_0.475MnP compound of single-phase with Co₂P-crystallographic structure was prepared by a multi-step solid sintering process. Co_0.525Fe_0.475MnP exhibits two successive magnetic transitions with the increasing temperature: a first-order magnetic phase transition from the antiferromagnetic (AF) to the ferromagnetic (FM) state at 285 K, and a second-order magnetic phase transition to the paramagnetic (PM) state at 375 K. The maximum value of magnetic-entropy change for a field change from 0 to 5 T is 1.1 J/(kg?K) at 303 K and -2.0 J/(kg?K) at 383 K. With the decreasing temperature, a minimum resistivity emerges near the T_FM-AF originating from the competition between antiferromagnetism and ferromagnetism. The compound experiences a metal-insulator transition at 35 K, which can be ascribed to spin disorder due to the Fe substitution for Co. The value of maximum magnetoresistance ratio is -2.5% at 200 K in an external magnetic field of 5 T. Magnetoresistance value decreases rapidly above antiferromagnetic temperature, confirming that the magnetoresistance originates from the influence of external magnetic field on the antiferromagnetic state.

Nickel electrode paste was prepared with powders of Ni, B and glass as raw material and rosin containing terpineol as organic binder. Two formulae of 70%, 15% and 15% as well as 68%, 16% and 16% of Ni, B and glass (mass fraction) respectively were adopted, which were applied on PTC semiconductor porcelain and then fired in air at 790~870^oC with varying processing parameters to produce Ni electrodes. The prepared electrodes were characterized by means of SEM with EDX. The room temperature resistance and square resistance of the electrode were measured by multimeter and RTS-8 four-probe tester respectively. Results show that after fired at 810~850^oC for 20 min, the prepared Ni electrodes on PTC semiconductor porcelain and other ceramics present excellent compatibility with substrates and good electrical properties. With the increasing fire temperature, the resistance and square resistance of the electrode decrease first and then increase, however both of them are the lowest for the electrode fired at 820^oC.

Multilayered films Ti/TiN with 5~40 nm modulation period were prepared on a high-speed steel substrate by multi-arc ion plating technology. The microstructure and mechanical property of the films were characterized by means of scanning electron microscopy (SEM), X-ray energy dispersive spectrometer (EDS), X-ray diffraction (XRD), nanoindentation and scratch test. The effect of modulation period on the performance of multilayered films Ti/TiN was investigated. Results show that the multilayered films Ti/TiN are uniform and dense with lamellar structure but without obvious features of columnar structure. TiN film is preferentially grown along the (111) direction. The film hardness increases firstly and then decreases with the decrease of the modulation period. The maximum hardness of 42.9 GPa and the maximum H/E value werer obtained when the modulation period is 7.5 nm, which indicates that the film possesses good combination of wear resistance and toughness. In addition, the adhesion of the multilayered films Ti/TiN is generally higher than that of the single-layered TiN film. When the modulation period is 7.5 nm, multilayered films Ti/TiN present a relatively high adhesion of (58±0.9) N.

Photocatalysts of cubic ZnIn₂S₄ and hexagonal ZnIn₂S₄ as well as a series of Cubic ZnIn₂S₄/hexagonal ZnIn₂S₄ composite with different molar ratios were synthesized via hydrothermal method. The crystal structure, microstructure and optical absorption property of the as-synthesized photocatalysts were characterized by means of X-ray diffractometer, scanning electron microscopy, transmission electron microscopy, photoluminescence spectrometer, Brunauer-Emmett-TeIler analysis and UV-visible diffuse reflectance spectroscopy. The photocatalytic activities of the prepared photocatalysts were evaluated through photocatalytic degradation of methyl orange under visible-light irradiation. Results show that all the composite photocatalysts have much better photocatalytic activity than that of the catalysts of cubic ZnIn₂S₄ and hexagonal ZnIn₂S₄ as well as the mechanically mixed ZnIn₂S₄ of the above two pure catalysts; Among others, the composite with more ratio 3:7 for cubic ZnIn₂S₄ to hexagonal ZnIn₂S₄ presents the highest photocatalytic activity with degradation efficiency for methyl orange up to 95.2% under visible-light irradiation for 30 minutes. This property can be attributed to the much larger specific surface areas and a direct Z-scheme photocatalytic process due to the close contact of cubic ZnIn₂S₄ and hexagonal ZnIn₂S₄ produced by the hydrothermal synthesis process.

Polyborosiliazne precursor was synthesized via multi-stage polymerization process with HSiCl₃, Me₆Si₂NH, BCl₃ and CH₃NH₂ as raw materials. Then SiBN ceramic fibers were obtained by melt spinning, curing and pyrolysis of the as-synthesized polyborosilazane precursor. The chemical structure, high temperature thermal stability, dielectric property and mechanical property of the polyborosilazane and its pyrolysis products were investigated by FT-IR, NMR, XRD, TEM and TGA. FT-IR and NMR. Results show that the polyborosilazane precursors prepared at different temperatures exhibited similar chemical structures, namely, containing Si-N, B-N and N-CH₃ bonds. The obtained SiBN ceramic fibers remained amorphous structure with 14 μm in diameter and 0.91 GPa in tensile strength after heat treatment at 1400^oC. The SiBN ceramic fibers have excellent thermal stability with only 1.5% mass loss in the temperature range from room temperature to 1400^oC. The dielectric constant and dielectric loss loss tangent magnitude of SiBN ceramic fibers are 2.6~2.8 and 10^-2 at 1100^oC, respectively.