The magnetic functionalized rGO/Fe₃O₄ was prepared by hydrothermal method with graphene oxide and ferric chloride as raw materials, and subsequently rGO/Fe₃O₄ particles were blend in epoxy resin to prepared composite rGO/Fe3O4/epoxy resin. The results show that the impact strength of rGO/Fe₃O₄/epoxy resin composites reaches 27 kJ/m² when the addition amount of rGO/Fe₃O₄ is 30%, which is 58.8% higher than that of the plain epoxy resin. In addition, the absorption performance of epoxy resin composite is significantly enhanced after the addition of rGO/Fe₃O₄. When the addition of rGO/Fe₃O₄ is 20%, the reflection loss of the rGO/Fe₃O₄/epoxy resin composite is less than -10 dB in the frequency range of 7.7~12.3 GHz. The effective absorption bandwidth (reflection loss<-10 dB) is up to 4.6 GHz, which covering the whole X-band. With the increase of graphene content, the position of the minimum reflection loss of rGO/Fe₃O₄/epoxy resin composites moves towards low-frequencies. It follows that by controlling the relative content of rGO and Fe₃O₄, the absorbing performance of rGO/Fe₃O₄/epoxy resin composites can be adjusted to the meet the requirements for materials of desired absorbing performance.

A novel spherical nano-ferric oxide of 40~60 nm in diameter was prepared by pyrolysis precursor method, with Fe (NO₃)₃·9H₂O as raw material and urea as precipitator. The prepared spherical nano-sized ferric oxide was characterized by XRD, SEM and EDS. The effect of Fe³⁺ concentration, reaction temperature and other factors on the particle size and morphology of nano-sized ferric oxide were investigated. The preparation conditions of nano-sized ferric oxide were determined and the formation mechanism of nano-sized ferric oxide was also analyzed. The results show that the crystallinity and particle size of nano-sized ferric oxide increase with the increase of temperature. The concentration of Fe (NO₃)₃·9H₂O has little effect on the particle size and morphology of the prepared nano-sized iron oxide. The formation mechanism of spherical ferric oxide nanoparticles is as follows: the iron source hydrolysates and crystallizes under hydrothermal conditions to generate brownish yellow flocculant precipitation FeOOH, and FeOOH dissolves and recrystallizes in conditions of high temperature and high pressure further to generate spherical ferric oxide nanoparticles.

A novel metastable β-Ti alloy (Ti-4Al-6Mo-2V-5Cr-2Zr) was designed, melt and wrought to prepare plates. Then the effect of solution treatment temperature on the microstructure and room temperature tensile properties of the as wrought alloy was investigated. Results show that a large number of α-phase precipitates from the β-matrix and gathers near slip bands when the solution temperature is lower than the phase transition temperature of the alloy. As the solution temperature approaches the phase transition temperature, the quantity of α-phase decreases and a part of the slip bands disappears. When the solution temperature is above the phase transition temperature, the alloy microstructure is composed fully of β-phase, while the slip bands disappear completely. As the solution temperature continues to rise, β-phase grains tend to aggregate and grow up. The alloy presents a good matching of strength and plasticity after solution treatment at 750℃×1 h. The corresponding ultimate tensile strength, yield strength and elongation are 957 MPa, 887 MPa and 11.7%, respectively.

Tripolyquinazoline-based conjugated microporous polymers (TQ-CMPs) were synthesized, and molybdenum sulfide (MoS₂) nanoparticles grown in-situ on the surface of TQ-CMPs via hydrothermal method as a new type of composite electrocatalyst for hydrogen evolution reaction. Its electrocatalytic hydrogen evolution activity was studied. As a result, when the mass ratio of the TQ-CMPs and MoS₂ is 2∶1 the electrocatalyst has excellent electrocatalytic activity for an overpotential of 71 mV and a Tafel slope of 52 mV·dec^-1 for hydrogen evolution reaction. TQ-CMPs have large specific surface areas, which improve the dispersion of MoS₂. The accumulation of MoS₂ was avoided effectively, and more MoS₂ edges was exposed, which improved the electrocatalytic activity. In addition, the abundant porous structure and extended π-conjugated framework of TQ-CMPs facilitated mass transport and charge transfer.

The deformation characteristics of 9Mn27Al10Ni3Si low density steel at 850~1050℃ with strain rate within the range of 0.01~5 s^-1 were investigated by using Gleeble thermal simulator, XRD, OM, SEM and TEM. The results show that when the steel is hot compressed at 850~950℃ with low strain rate (0.01~1 s^-1), the flow stress of the steel increases obviously as the strain reaches a certain critical value, which may be due to the precipitation and coarsening of κ-carbides, and the increase of friction coefficient of the steel during hot compression. With the increase of strain rate, the number of twins increases significantly, which can speed up the process of dynamic recrystallization of austenite, however, during thermal compression by high strain rate, the dynamic recrystallization process is more significant rather than by low strain rate. Due to the softening effect of recrystallization, the abnormal rise of flow stress gradually weakens or even disappears.

The effect of three type of heat treatments on the microstructure and tensile properties of a novel metastable β-titanium alloy Ti-6Mo-5V-3Al-2Fe-2Zr was investigated, namely solution and single-stage aging, solution and two-stage aging, as well as solution and furnace cooling. The results show that: compared with the solution and single-stage aging treatment, the strength of the alloy was improved with the decrease of the spacing of secondary α phase precipitated within grains and the increase of its volume fraction by solution and two-stage aging treatment. Continuous α phase formed at grain boundary resulted by the above two heat treatment processes, which leading to poor plasticity of the alloy. Compared with the above two heat treatment processes, the heat treatment of solid solution and furnace cooling could induce obviously the decrease of the spacing of the intracrystalline secondary α phase precipitated, thus increase the amount of α_wgb phase formed along the grain boundary and grew into the grain, thereby increase significantly the strength and plasticity of the alloy i.e., the tensile strength of the alloy reaches 1421 MPa, and the fracture elongation is 7.7%. Relative to the volume fraction of the secondary α phase, the spacing is the main factor affecting the strength of the alloy. With the decrease of the spacing of the secondary α phase, the alloy strength increases.

The evolution of hardening, microstructure and precipitate of Al-Mg-Si alloy during early artificial aging process were investigated by means of microhardness tester, differential scanning calorimetry (DSC) and high-resolution transmission electron microscopy (HRTEM). The results show that the alloy aged at 170℃ has higher peak hardness. At the early aging stage, the high number of solute clusters and GP regions precipitated within grains, and the hardness of the alloy significantly increased. The hardness of the alloy reaches the peak value after being treated at 170℃ for 4 h, and the acicular β"-phase is the main precipitated phase within grains. The three-dimensional coherent strain at the interface between β"-phase and Al matrix is the main reason for the strengthening of the alloy. At the same time, the precipitated particulates distributed discontinuously along grain boundary. With the increase of aging time, the β"-phase coarsened and the continuity of the precipitated particulates decreased. During the over-aging stage, the hardness of the alloy is greatly reduced due to the severe coarsening and the decrease of number of the precipitates. At the initial stage of aging, the precipitation sequence of the alloy is as follows: supersaturated solid solution → spherical atomic clusters → needle-like GP region → needle-like β"-phase.

The phosphorus-containing graphene (PhA-G) was prepared by pyrolysis method with phytic acid (PhA) as raw material, and next the PhA-G/SiR composite anticorrosion coating was prepared with silicone resin (SiR) as film forming material. The structure and morphology of phosphorus-containing graphene was characterized by means of Raman spectroscope, X-ray photoelectron spectroscope (XPS), scanning electron microscope (SEM), transmission electron microscope (TEM) and atomic force microscope (AFM). The prepared coatings with the different additive amount of PhA-G (1%~4% in mass fraction), were comparatively examined by means of measurements of contact angle, water absorption, potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), as well as salt spray test. The results show that the protectiveness of PhA-G/SiR composite coatings for metal substrate is greater than that of the plain SiR coating, and graphene oxide/silicone resin (GO/SiR) coating. The PhA-G/SiR composite coating exhibits good hydrophobicity and excellent corrosion resistance when the mass fraction of PhA-G is 3%. Correspondingly, which exhibits hydrophobic contact angle of 103.5° and water absorption rate of 3.72%, while corrosion current density of 3.53×10^-10 A/cm² and electrochemical impedance as high as 3.82×10⁷ Ω·cm² in 3.5%(mass fraction) NaCl solution. Furthermore, the PhA-G/SiR composite coating presents excellent resistance to salt spray testing, up to above 960 h.

High-quality films of lead-free piezoelectric xMn-doped KNaNbO₃ (x = 0, 0.05, 0.10) were successfully deposited onto Pt(111)/Ti/SiO₂/Si(100) substrates by sol-gel method. The effect of Mn doping and seed layer of niobium oxide on the microstructure, dielectric properties, ferroelectric properties, and leakage current of the KNN films was investigated in detail. The results show that Mn doping can significantly improve the ferroelectric properties and reduce the leakage current of the prepared films. After inserted a seed layer of niobium oxide in between the films and the substrate, the leakage current related mechanism of KNN films changes from space charge conduction and ohmic conduction to ohmic conduction and Schottky emission, correspondingly, the leakage current is further reduced. It is found that when the electric field is 600 kV/cm, the maximum polarization value of the 10% mol Mn doped KNN films with a inserted seed layer is 20.33 μC/cm², and the residual polarization value is 2.94 μC/cm².