Fe-nanoparticles (NPs)/ carbon fibers (CF)/epoxy resin (EP) based composites were designed and fabricated. The microwave absorbers Fe-NPs were prepared by the direct current (DC) arc-discharge plasma method and modified with silane coupling agent KH550. The reflection losses of composites were measured in the frequency range of 2-18 GHz and the effects of Fe-NPs, CF and the geometry feature of test plates on the microwave absorbing properties were investigated. Results show that reflection loss peaks appear at low frequency and the microwave absorbing properties are enhanced due to the addition of CF. With the increasing mass fraction of Fe-NPs the microwave dissipation increases and the reflection loss peaks move towards the low frequency. The concentration gradient of Fe-NPs in EP matrix was caused by gravity during the preparation process and it causes reflection loss differences between the two surfaces of a plate, which is beneficial for microwave to enter the composite plate and be absorbed by properly setting the plate.

Fe/SiO₂composites were prepared by sol-gel method firstly and further on which zirconcene dichloride (Cp₂ZrCl₂) was deposited to prepare a catalyst Fe/SiO₂/Cp₂ZrCl₂. Then particulates of Fe/SiO₂/PE composites were produced by polymerization filling technique with ethylene and the Fe/SiO₂/Cp₂ZrCl₂ catalysit. The obtained Fe/SiO₂/PE composite particles were characterized by scanning electron microscopy(SEM), energy dispersive X-ray spectroscopy(EDX), infrared spectroscopy(IFR), inductively coupled plasma spectroscopy(ICP), thermal gravimetric analysis(TGA) and laser particle size analyzer, respectively. The results show that the Fe core was perfectly coated by a SiO₂ layer for the Fe/SiO₂ composites, which could act well as a supporter for the deposition of Cp₂ZrCl₂. The Fe/SiO₂/Cp₂ZrCl₂ catalyst showed a high activity for the ethylene polymerization process. PE chains grew and attached on the Fe/SiO₂/Cp₂ZrCl₂ composites gradually, until the Fe/SiO₂ composites were entirely coated. Moreover, the Fe/SiO₂/PE particles were found to agglomerate significantly during ethylene polymerization. Both the Fe/SiO₂/Cp₂ZrCl₂ catalysts and Fe/SiO₂/PE composites had irregular shapes, and the latter tended to duplicate the shape of the former. The Fe content in the Fe/SiO₂/PE composites can be adjusted by varying the time and pressure of the polymerization process. Finally, the range of the molecular mass distribution of the PEs produced by this process is narrow.

Corrosion behavior of carbon steel beneath seawater droplets was investigated by using the wire electrode technique (WBE). It was found that anodic and cathodic current decreased gradually with the increasing time, then eventually kept stable. Furthermore, the current distribution over the WBE surface beneath seawater droplets of different sizes was studied. Beneath a smaller droplet, the carbon steel was more easily to form an asymmetric electrochemical area. In addition, a concept of droplet spreadability was defined. The average current density increased exponentially with the increasing droplet spreadability, the maximum value and the standard deviation of the anodic current density increased linearly, at the same time, the corrosion intensity enhanced.

Polyacrylonitrile (PAN)-based carbon fiber was surface modified with HNO₃ (65-68%) and silane coupling agent (hk550) and of which the structural and surface characteristics of were investigated by SEM, FT-IR, and X-ray photoelectron spectroscopy (XPS). Then the surface modified carbon fiber reinforced phenolic matrix composites were prepared. The tensile strength and the friction performance of the composites were examined by tensile testing machine and integrated micro-nano-mechanical test system (UNMT-1) respectively. The results showed that the surface modification with HNO₃ and hk550 could enhance the surface chemical activity and roughness of the fibers, resulting in better interfacial adhesion between carbon fibers and phenolic resin matrix, therefore, improved the tensile strength and reduced the wear rate of the composites.

Effect of annealing treatment in a temperature range of 850-1050℃ on the evolution of microstructure involved with austenite, ferrite and carbides etc., as well as the mechanical properties and fracture behavior was studied for a cold rolled Fe-Mn-Al-C low density steel. The results show that the experimental steel annealed at 850℃ exhibits a complex microstructure consisted of austenite, banded d-ferrite, a-ferrite and small amount of carbides; there also existed intercrystalline network of ferrite and carbides which resulted in higher strength and poor plasticity, thus the steel becomes susceptible to cleavage fracture; the steel annealed at 900-1050℃ consisted of recrystallized austenite as matrix, in which the volume fraction of a-ferrite decreased with the increasing temperature, while the band like d-ferrite was crushed into islets and distributed in the matrix discontinuously; as the growth of d-ferrite was more obvious than that of austenite, larger volume fraction of ferrite did occur, which resulted in high intensity of X-ray diffraction peaks of ferrite; the microstructure evolution during annealing lead to decrease of tensile strength and increase of total elongation with the increasing temperature; the experimental steel annealed at 1000℃ exhibits excellent combination of strength and ductility: i.e. tensile strength 1003.1 MPa, total elongation 41.28% and product of strength with ductility 41.4 GPa%. Therefore, to acquire the optimal combination of strength and ductility, the cold-rolled Fe-Mn-Al-C steel should be annealed at temperatures above 950℃. Furthermore, the measured density of 6.55 gcm^-3 ensures this kind of ultra-high strength steel a remarkable weight reduction effect of 16.6%.

Bulk Nb-doped lead telluride Pb_1.1Te was prepared by using a combined process of mechanical alloying (MA) and spark plasma sintering (SPS). Then its transport properties such as electrical resistivity, Seebeck coefficient and thermal diffusion coefficient were measured in a temperature range from 323 K to 673 K. As a result, the doped Nb can effectively enhance the phonon scattering ability of the lead telluride Pb_1.1Te, and optimize its electrical performance as well. Large power factors of over 20 mW/(cm·K²) were obtained in a wide temperature range (523-623 K). In addition, the thermal conductivity decreased with the increasing Nb content, which may also be resulted from the increase of the phonon scattering ability, thereby an optimal ZT value may be found. A maximum ZT value of 1.27 was obtained for Pb_1.03Nb_0.07Te at 673 K, which was twice as high as that for the un-doped Pb_1.1Te.

Effect of nitrogen addition on continuous cooling transformation behavior of vanadium microalloyed steels was investigated. Therefor, CCT curves of three experimental steels with different vanadium and nitrogen content were measured by thermal dilatometer; the microstructural evolution of the steels with the varying cooling rates was characterized; their precipitation behavior was tracked, and planer lattice misfit degree of the precipitates with the ferrite matrix was calculated. The results show that ferrite transformation is promoted by nitrogen addition, and the starting temperature of transformation and the critical cooling rate for full bainite transformation are increased as well. For cooling rates in a range 0.8-1.6℃/s, the microstructure of steels with low nitrogen consists of granular bainite + lath like bainite, while acicular ferrite also exists; during or after the γ-α transformation vanadium compounds in low nitrogen steels precipitate mainly as VC, the quantity of which increases with the increasing vanadium content. However, for the steel rich in nitrogen, vanadium compounds precipitate as VN in austenite at high temperature. The lattice misfit degree of ferrite with the precipitates of austenite, VC and VN, which occurred at 900℃are 6.72%, 3.89% and 1.55% respectively. It indicates that VN precipitates act as preferential nucleation sites for ferrites and promote the ferrite transformation.

Pre-alloyed powders of Ti-47Al-2Cr-2Nb-0.15B (%, atom fraction) were prepared by an electrode induction melting gas atomization process, and powder metallurgy (PM) γ-TiAl alloys were prepared by hot isostatic press (HIP). Pre-alloyed powders of γ-TiAl were characterized. A comparison study was made between vacuum degassed and not degassed for the pre-alloyed powders and the PM alloys were subjected to tensile and rupture life test at different temperatures. Infrared spectrum analysis showed that the powders would absorb H₂O when exposed in air. By getting rid of the absorbed H₂O and O₂ through a carefully designed vacuum degassing pre-treatment, the numbers of voids in the prepared PM γ-TiAl alloys decreased obviously, correspondingly the rupture life, as well as the consistency of room temperature tensile elongation, was also improved. In order to find out the influence of container materials on the microstructure and mechanical properties of the PM γ-TiAl alloys, two different container materials (CP-Ti and mild steel) were adopted. Experimental results showed that a lot of obvious voids appeared in the reaction zone due to severe reaction diffusion between the mild steel container and the PM γ-TiAl alloys when HIPed at 1260^oC. The shielding effect of the mild steel container was stronger than that of the CP-Ti container, thus the densification shrinkage process of the CP-Ti canned PM γ-TiAl alloys would be more fully completed when HIPed at 1230^oC compared with that of the mild steel canned PM γ-TiAl alloys, and thereby both of the yield and tensile strength were both improved. The γ-TiAl alloys prepared by powder metallurgy route present more uniform microstructure, finer grain and better properties compared with the casting alloys. Furthermore, the PM γ-TiAl alloys had no texture which was very common for the casting alloys.

Double-shell phase change nano-capsules were prepared by the emulsion interfacial polymerization method with phase change materials as core, polystyrene as inner shell, hydrophilic chitosan as outer shell, with a 1:1 ratio of core to shell, sodium dodecyl sulfate as emulsifier, hexadecane as co-emulsifier and azodiisobutyronitrile as initiator. The prepared capsules were characterized by fourier transform infrared (FT-IR), differential scanning calorimetry (DSC), scanning electron microscope (SEM), laser particle size analyzer (LPSA) etc. The results show that the morphology of the double-shell phase change nano-capsules was greatly influenced by the kind of cores, the amount of emulsifier, co-emulsifier and initiator, and also related to phacoemulsification time and mixing speed.

Carbon microspheres (CMSs) were surface modified by the acid oxidation method and then grafted with aniline (An) by chemical synthesis to prepare compound CMSs-An. The CMSs-An/PET composite materials were prepared by melt blending CMSs-An and polyethylene glycol terephthalate (PET). The morphology, dispersiveness, thermal stability, flame retardant property and mechanical property of CMSs-An/PET materials were characterized by SEM, IR spectra, TG, oxygen index tester and vertical burning apparatus. The results show that, the aniline modified CMSs have better dispersiveness than that of the original CMSs in the PET matrix, and the tensile strength of CMSs-An/PET is 20.8% higher than that of CMSs/PET; in comparison with the pure PET, the CMSs-An/PET composite exhibits better performance: its thermal stability increased, limiting oxygen index increased by 7.5 and reached to 29.2, and vertical burning grades increased from V-2 level to V-0 level according to the national standards.

Three Functional ionic liquids of 1-(2- hydroxyethyl)-3-methyl imidazole chloride ([HeMIM]Cl), 1-ethylamine-3-methyl imidazole bromide ([AeMIM]Br) and 1-carboxy ethyl-3- methyl imidazole chloride ([CeMIM]Cl) were synthesized and characterized by FTIR and HNMR. Then straw was dissolved in the three ionic liquids respectively to produce three solutions of straw, which were further in situ blended with phenol and formaldehyde to prepare phenolic resin composites. The effect of the type of ionic liquids on the dissolution rate of straw and the effect of solutions of straw on the properties of phenolic resin were investigated. The results show that the properties of phenolic resin composites were improved obviously by the three solutions of straw. Among the three ionic liquids, the [CeMIM] Cl is the best solvent for straw to produce the solution, with which the lowest free formaldehyde containing phenolic resin composites may be synthesized; while phenolic resin composite synthesized with the [AeMIM] Cl solution of straw exhibits the best mechanical performance: its tensile strength increased from 3.28 MPa to 9.48 MPa and impact strength increased from 0.93 kJ/m² to 5.88 kJ/m² respectively in comparison with those of the ordinary phenolic resin.

Graphene oxide (GO) was prepared by chemical oxidation-sonicated crushing method with flake graphite, sulfuric acid and potassium permanganate as raw materials. The prepared GO was characterized by means of spectroscopy SEM, laser granulometer, FT-IR, UV-vis and AFM. The results show that the few-layered GO could be differentiated from the multi-layered graphite oxide in a solution of the mixture of the two by observing the variation of the intensity and the profile of absorption peaks around 230 nm in the UV-vis spectroscopy. Based on this phenomenon, the qualitative and quantitative analysis of graphene oxides in the solution can be realized. Thereby the optimal conditions for the preparation of graphene oxide can be obtained. It is proposed that the appearence of multi absorption peaks nearby 230 nm in the UV spectra of GO may be attributed to the existence of a peculiar structure of discontinues p-p* conjugated system in the graphene oxide.