A ceramic coating of 50 μm thick on the surface of friction stir welding (FSW) joint on 2219 aluminum alloy was fabricated by microarc oxidation (MAO) technique in the silicate electrolyte. The surface morphology, phase constituent and microhardness of the coatings on the parent phase and FSW joint of aluminum alloy were investigated, furthermore the interactions of alloy microstructure and MAO coating growth were analyzed. The results show that the effect of microstructure of aluminum alloy on growth of MAO coating is weak, and the properties of MAO coatings on the parent phase and FSW joint of aluminum alloy are almost same. The ceramic coatings at different zones of joint consist of α-Al₂O₃, γ-Al₂O₃ and mullite (3Al₂O₃·2SiO₂) phases. The microhardness of coatings on the parent phase and FSW joint of aluminum alloy is same, which average microhardness is about HV 1500. In addition, the microstructure of aluminum alloy near the coating/alloy interface is not influenced by high-temperature process of microarc discharge.

In order to improve the ablation property of C/SiC composite at ultra high temperatures, ZrB₂ coatings upon C/SiC composite were prepared by pasting the slurry of zirconium powder, boron powder and phenolic resin, followed by high temperature sintering. The reactions in the sintering process were investigated, and the component, microstructure and ablation property of the coatings were characterized. The results show that zirconium powder reacts firstly with pyrolytic carbon to form ZrC till 1200℃, and then ZrC reacts with boron to form ZrB₂ during 1400℃-1600℃. When the mole ratio of Zr/B/C is 1.0/1.5/1.0, the coating sintered at 1600℃ is composed of mainly ZrB₂, small amount of ZrC and ZrO₂. After ablation for 60 s in oxyacetylene torch environment, the C/SiC composite with ZrB₂ coating shows a linear recession rate of zero, due to the ZrO₂ formation from ZrB₂ oxidation, while the C/SiC composite without coating shows a linear recession ratio of 0.064mm/s.

Optically transparent Cu nanocrystalline/OPAA composite film was successfully prepared by electrodepositing Cu into ordered porous anodic alumina (OPAA) template using constant voltage direct current technique. The morphology, structure, linear optical absorption, third-order optical nonlinearity and ultrafast dynamics of the Cu/OPAA composite were characterized by field emission scanning electron microscope (FESEM), transmission electron microscope (TEM). UV-Vis spectrophotometer, Z-scan technique and femtosecond pump-probe experiment. The results show that Cu nanoparicles have diameters of 40–50nm with face center cubic structure and disperse in the branched pores of the OPAA template, which induce a surface plasmon resonance (SPR) absorption at 584 nm. When the probe optical wavelength is far away from the SPR wavelength, Cu nanocrystalline/OPAA composite film possesses a character of light-induced absorption. When the probe optical wavelength is near the SPR wavelength, it possesses a photo-bleaching character. The composite film has a non-resonant third-order nonlinear susceptibility of 0.73×10^-9 esu and a response time of 1.3 ps.

Graphene/CdS quantum dot composites were prepared via in situ synthesis and its electrochemical performances as anode material for lithium-ion batteries were investigated. Ac impendence spectra reveal that electrolytes form a fine solid electrolyte interphase film (SEI) on the surface of the graphene/CdS quantum dot composites. The initial discharge capacity of the lithium-ion battery using graphene/CdS quantum dot as anode is about to 1264.7mAh/g and reversible capacity is 888.9mAh/g after 20 cycles. The results indicate that the CdS quantum dot improve the stability of the graphene structure and the conductivity between graphene sheets, so the electrochemical performance of graphene/CdS quantum dot composites as anode materials is obviously better than that of graphene materials.

Two different tin salts, SnCl₂^.2H₂O and SnCl₄^.5H₂O, were employed in the synthesis of Sn-doped TiO₂. And the crystal structures and visible-light photocatalytic activities between Sn2+-doped TiO₂ and Sn⁴⁺-doped TiO₂ were compared. The results show that both the anatase-to-rutile phase transformation temperature and the crystal growth of TiO₂ are remarkably decreased by Sn dopant, and the Sn²⁺ dopant shows the higher efficiency than Sn⁴⁺ dopant. And despite the similar spectra of XRD and FTIR, Sn²⁺-doped TiO₂ displays higher visible-light photocatalytic activities than Sn⁴⁺-doped TiO₂, due to the half-filled d electronic orbit of Sn²⁺. Mesoporous montmorillonite was chosen as the supporting material for Sn²⁺-doped TiO₂, due to its high crystalization and large specific surface area. When Sn²⁺-doped TiO₂ was loaded on mesoporous montmorillonite, the resualtant samples had no significant difference in XRD patterns and FTIR spectra as compared with the supporting material, and no obvious peaks were found related to Sn²⁺-doped TiO₂. While the UV-Vis analysis shows that the adsorption edges of Sn²⁺-doped TiO₂ display red shift after loaded onto mesoporous montmorillonite. As a result, the resultant compound photocatalyst exhibits higher visible-light catalytic activity than unloaded Sn²⁺-doped TiO₂, which is due to the interactions between mesoporous montmorillonite supports and Sn²⁺-doped TiO₂. This might provide a promising way to improve the photocatalytic activity of TiO₂ with minimized cost and widened light-response region.

Er³⁺: LiYF₄ single crystal was grown by the Bridgman method under non-vacuum atmosphere. The single crystal was in size of 9mm×68mm with 1mol% concentration of Er³⁺ ions. Optical properties of the single crystal including the refractive index, UV and IR transmission spectra, absorption spectrum, near-infrared emission spectrum under 980nm excitation and mid-infrared emission spectrum under 792nm excitation were measured. The intensity parameters (?t, t=2,4,6), oscillator strength(fcal), transition probabilities (A), branching ratios (B) and radiation lifetimes (t_rad) of Er³⁺ ions in the LiYF₄ were estimated by using the Judd-Ofelt theory. The near- and mid-infrared fluorescence properties of the sample were discussed. The results indicate that near infrared fluorescence at 1.5μm corresponding to the Er³⁺: ⁴I_13/2→⁴I_15/2 transition is observed under 980nm excitation while mid-infrared fluorescence at 3.0μm corresponding to the Er³⁺: ⁴I_11/2→⁴I_13/2 transition is detected under 792 nm excitation. The reason that caused the weakening of fluorescence at 3.0μm is analyzed.

Y(NO₃)₃, HfCl₄ and EDTA as raw materials,Y₂Hf₂O₇ nanopowder were successfully prepared by combustion synthesis method. The as-burnt powder were calcined at 1200℃ and then ball-milled for 15h. The powders were formed into green bodies with a size of 20mm×2.5mm by cold isostatic pressing (CIP, 200MPa). Y₂Hf₂O₇ transparent ceramics were obtained by sintering the green bodies at 1850℃ in vacuum for 6h. The resultant ceramics showed a transmittance of 50% in the visible spectral region. The sintering behavior of the prepared Y₂Hf₂O₇ powders was investigated. When the sintering temperature was above 1850℃, sintering temperature had little effect on the transmittance of the ceramic. Meanwhile the grain size became larger with sintering temperature increasing.

Lead-free piezoelectric ceramics Sr_2-xCa_xNaNb₅O₁₅+ywt%MnO₂ (x=0.05-0.35, y=0, 0.3, 0.5) (SCNN-M) were fabricated by conventional solid-state processes, and their microstructure, phase transformation, dielectric, piezoelectric and ferroelectric properties were investigated systematically. Our results reveal that Ca²⁺ ions have entered into the Sr₂NaNb₅O₁₅ lattices to form a solid solution and the doping of MnO₂ is effective in promoting the densification of the ceramics. With the MnO₂ doping, all the ceramics can be well sintered at a relative low temperature and exhibit a dense and pure tungsten-bronze structure. The addition of Ca²⁺ has no remarkable effect on the microstructure and MnO2 caused a significant promoted grain growth. Compared with the pure SCNN ceramics, the dielectric and piezoelectric properties of SCNN-M ceramics were greatly enhanced. At room temperature, the SCNN-M ceramics with x=0.5 and y=0.5 exhibits the optimum properties: piezoelectric coefficient d₃₃=190pC/N, mechanical quality factor Q_m=1455, planer electromechanical coupling factors K_p=13.4%, thickness electromechanical coupling factors K_t=36.5%, dielectric constant E_r=2123, loss tangent tand=0.038, remanent polarization P_r=4.76uC/cm², spontaneous polarization P_s=9.36uC/cm², coercive field E_c=12.68kV/cm, and curie temperature T_c=260℃. Therefore, the SCNN-M ceramics are a good candidate material for lead-free piezoelectric ceramics.

A series of polyacrylonitrile-based hollow-porous carbon fibres (PAN-HPCFs) were prepared by oxidating PAN hollow-porous fibers in air and carbonizing their cured fibers in nitrogen. The effects of preoxidation and carbonization heating rate on the microstructure, composition, electrical volume conductivity and complex permittivity were investigated. The microstructure of the obtained PAN-HPCFs is changed greatly by the heating rate. The electrical volume conductivity and complex permittivity decrease with the increase of heating rate. The electrical volume conductivity is in the range 1997.14 S/m to 153.39 S/m with the preoxidation heating rate increasing from 0.5℃/min to 4℃/min. At 2 GHz, the value of ε″ of composites of paraffin and PAN-PHCFs decreases from 70.35 to 6.99 when preoxidation heating rate increases form 0.5℃/min to 4℃/min. Results indicate that the electrical conductivity and complex permittivity of PAN-HPCFs can be adjusted by the heating rate.

The influence of ceramic binder contents, SiC particle sizes, and sintering temperatures on the porosity and flexural strength of SiC porous ceramics for high-temperature gas filtration were investigated. The composition of SiC porous ceramics was measured by X-ray diffraction. The porosity of SiC porous ceramics decreased with increasing the ceramic binder contents, and the SiC porous ceramic with a relatively high porosity of 37.5% and flexural strength of 27.63MPa was obtained with ceramic binder content of 15wt%. Both the porosity and flexural strength of SiC porous ceramics increased with SiC particle sizes decreasing from 300um to 87um, and the porosity increased from 35.5% to 42.4%, while the flexural strength increased from 19.92MPa to 25.18MPa. In addition, the porosity of SiC porous ceramics quickly decreased from 38.7% to 35.4% with sintering temperatures increasing from 1300℃ to 1400℃, but the flexural strength of SiC porous ceramics had only a slight change, mainly standing at about 27MPa. Thus, the sintering temperature of SiC porous ceramics should be selected around the melting point of ceramic binder (1300℃).

Porous monoliths with high porosity and improved high temperature stability are required in heat insulation. Mesoporous SiO₂ powder was synthesized from tetraethyl orthosilicate using oil-in-water microemulsions composed of non-ionic surfactant P123 and 1,3,5-trimethylbenzene as template. Porous SiO₂ monoliths were prepared from the mesoporous SiO₂ powder by dry pressing followed by sintering. Porous SiO₂/Al₂O₃ monoliths and SiO₂/TiO₂ monoliths were prepared from mesoporous SiO₂ powders coated with boehmite Sol and titania Sol respectively. XRD, SEM, TEM, N2 adsorption and Archimedes method were employed to characterize the powders and the monoliths. The thermal stability of the monoliths was studied. The porosity of the silica-based monoliths sintered at 600-700℃ is about 74%?76%. Compared with SiO₂ monolith, porous SiO₂/Al₂O₃ monolith has much better thermal stability at 800-1000℃ and porous SiO₂/TiO₂ monolith has an improved thermal stability at 800-900℃. It is indicated that alumina coating on porous silica particle surface can improve the high temperature stability of SiO₂/Al₂O₃ monolith.

Al₂O₃/Ti(C, N)-Ni-Ti composites were synthesized by vacuum hot press sintering. The effect of Ni and Ti on microstructure and mechanical properties were investigated. The results indicated that the composites with Ni and Ti addition were composed mainly of Al₂O₃, Ti(C, N) and Ni with no Ti. Due to its high reactivity, Ti may react with the C containing atmosphere produced by the graphite die in the hot pressing process to form TiC, or with the possible N₂ resulted from the small amount decomposition of Ti(C, N) at high temperature to form TiN, which is beneficial to the elimination of pores. Suitable addition of Ni promotes densification of the composites via liquid phase sintering, and increases relative density of the composites. Ni can also increase fracture toughness of the composites through crack deflection and crack bridging. With the addition of 5vol% of mixture of Ni and Ti (equal molar amount of Ni and Ti), the composite hot-pressed at 1500℃ has a relative density of 99.6%, Vicker’s hardness of 21 GPa, three point bending strength of 818 MPa, and fracture toughness of 8.1 MPa·m^1/2.

A nanocomposite (PPy/F-MWCNTs) were successfully synthesized by the in-situ chemical oxidation polymerization with acid-treated multi-walled carbon nanotubes (F-MWCNTs) and polypyrroles(PPy). The as-prepared composite was characterized by Fourier transformed infrared spectra (FT-IR), UV-Vis diffuse refflection spectroscope (UV-Vis DRS), thermal gravimetric analysis (TGA), X-ray diffraction (XRD), Branauer-     Emmett-Teller analysis (BET), field-emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM). The results reveal that the F-MWCNTs is well coated with about 25-40nm thick polypyrrole, and the surface specific areas of PPy/F-MWCNTs is about three times than that of pure PPy. The sensors fabricated by PPy/F-MWCNTs exhibit higher sensitivity, better response/reproducibility towards NH₃ vapor at room temperature than that fabricated by pure PPy or F-MWCNTs. The sensitivity is 1.9 even to 200×10^-6 of NH₃ and the response time is 135s. In addition, compared with MWCNTs untreated with acid, the as-prepared PPy/F-MWCNTs also exhibits higher sensitivity than that prepared without acid-treated MWCNTs.

2D-C/[SiC-(B-C)] samples modified by B-C ceramic as self-healing component and boron-silicon glass phase were assessed by environmental engine experiments at 1000℃, 1200℃, 1350℃. Furthermore, tensile strength and three point bending strength of the samples were tested at room temperature after assessment. The results showed that the tensile strength and three point bending strength increased with the increase of assessment temperature, however, three point bending mechanical properties increased at a higher rate. SEM results showed that the glass phase generated by oxidization of B-C self-healing component and the boron oxide glass phase filled pores and cracks effectively. According to the experiments results, the self-healing mechanisms in aero-engine combustion chamber of such two samples were discussed.

Hollow hydroxyapatite microspheres consisted of a hollow core and a porous shell were prepared by converting Li₂O-CaO-B₂O₃ glass microspheres in dilute phosphate solution at 37℃. Human bone morphogenetic protein (rhBMP-2) was loaded in the resultant microspheres, and the in vitro release behavior of rhBMP-2 was studied. Furthermore, cell culture technique and ALP kit were used to investigate the effect of the released rhBMP-2 on cell activity. After incubation with rhBMP-2 loaded microspheres, the alkaline phosphatase (ALP) activity of the rat bone marrow mesenchymal stem cells (MSCs) was evaluated. It was found that rhBMP-2 could be released slowly from the hollow HA microspheres for an extended period time up to 1000h. The present delivery system established possessed higher biological activity as compared with pure rhBMP-2.

In order to improve the physical properties and biocompatibility of the aortic stent-graft, the effects of heat treatment and electrochemical polishing on nickel-titanium (NiTi) alloy wire during the stent-graft preparation were studied. It is found that heat treatment could help shaping the stent-graft and enhance the mechanical properties of the NiTi wire. The ideal heat-treatment process is heating at 480℃ and 510℃ for 7 min, respectively. By electrochemical polishing, the surface quality and fatigue life of the wire is highly improved. Meanwhile, electrochemical polishing results in reduction of the possibility of the mural thrombus formation and endothelial hyperplasy.

Alumina modified feldspathic dental ceramics were fabricated by common sintering method, using alumina as an additive to strengthen and toughen the feldspathic ceramics. The prescription and the sintering technology of the feldspathic ceramics composite materials were identified. The influences of sintering technology on the machinability, the microhardness and the flexural strength were discussed. The feldspathic ceramics composite materials were characterized by XRD and SEM. The results reveal that the sintering temperature of feldspathic ceramics is raised with the increase of alumina content. Where the relative density of the feld spathic ceramics added with 20wt% Al₂O₃ reach 97.9% after sintered at 1200℃. Furthermore, the property of feldspathic ceramics is improved obviously with the addition of alumina. The abrasion rate reaches the maximum with the addition of 5wt% alumina, the microhardness is increased by 26.9% with addition of 20wt% Al₂O₃, and the flexural strength is increased with the increase of alumina content.

TiO₂ nanotubes on titanium with different diameters were prepared by anodic oxidation after heat-treated at 450℃. Hydroxyapatite (HA) coatings containing bovine serum albumin (BSA) were produced on the nanostructured surface through biomimetic co-deposition. The TiO₂ nanotube layers with 170nm diameter has a better mineralization ability compared that with diameter of 100nm and 50nm, And the HA formation ability is enhanced with increase of the diameters. The bonding strength of the coating to the nanotube layers with large diameter is higher than that with small diameter, and the maximal strength can reach 16.95MPa. Moreover, the pre-mineralization in vacuum significantly enhances the bonding strength, and increases growth rate of the coating. The BSA-HA coating with high bonding strength can fastly form on TiO₂ nanotube layers by pre-mineralization in vacuum and then biomimetic co-deposition, which would be a promised method for preparing titanium-based bioacitive coatings.

Zinc oxide thin films doped with different neodymium (Nd) contents (1at%, 2at% and 3at%) were grown on Si (100) substrates by radio frequency magnetron sputtering. X-ray diffraction (XRD) patterns show that all of the ZnO thin films have highly preferred growth along c-axis direction. The intensity of (002) diffraction peaks weakens and the gain size decreases with the increasing of Nd dopants. The optical transmittance of all the films exceeds 85% in the visible light region, and the optical band gap increases from 3.30 eV to 3.40 eV with the increasing of the Nd dopants. The surface chemical state of ZnO thin films is examined by X-ray photoelectron spectroscope (XPS), confirming that Nd element exists as Nd³⁺ in the films. Contact angle test is also employed to analyze the effect of Nd dopant on the wettability and surface energy. The platelets adhesion experiment shows that fewer platelets adhere and deform on ZnO and Nd doped ZnO thin films. Nd element and hydrophobility surface are the main factors leading to the better blood compatibility of ZnO thin films.

A novel porous poly (lactic acid) (PLA)/SiO₂-CaO(n(SiO₂):n(CaO)=1:1) composite membrane is synthesized by Sol-Gel method. The microstructure and composition of the composite membranes are characterized by Fourier transform infrared (FTIR) spectroscope and scanning electron microscope (SEM). The surface zeta potential is monitored by the SurPASS electrokinetic analyzer. The bioactivity is evaluated by investigating the formation of apatite on the surface of the composite membranes in simulated body fluids and the cytotoxicity is evaluated by MTT experiments. After soaked in simulated body fluids for 7d, the surface of the PLA/SiO₂-CaO composite membranes is covered by an apatite layer with an orderly ring structure. The surface zeta potential of the composite membranes decreases with increasing SiO₂-CaO contents suggesting better bioactivity. The PLA/SiO₂-CaO composite membranes do not induce cytotoxcity to MG-63 cells and support cell proliferation.

Nanostructured Al₂O₃-13wt% TiO₂ coatings were prepared by plasma spraying agglomerated nanocrystalline powders formed via spray drying method. The phase composition, microstructure, microhardness and fracture toughness of the coatings were investigated. It is found that the nanostructured coatings exhibited a unique bimodal microstructure consisting of two distinct regions: one of the regions is Fully Melted (FM) and solidified as lamellar structure, and the other is Partially Melted (PM) particulate microstructure with embedded nano or sub-micron particles retained from the starting powders. Furthermore, the percentage of PM region, which is proportional to unmelted α-Al₂O₃ nanoparticles, in the coatings can be controlled by the critical plasma spray parameter. Such a characteristic of blended microstructure of the coatings is clearly confirmed from a bimodal distribution of their mechanical properties. The Weibull statistical analysis shows that the microhardness and fracture toughness of the coatings present a bimodal distribution, the mean value and the dispersity of microhardness of PM region are lower than those of FM region, but the mean value and the dispersity of fracture toughness of PM region are both higher than those of FM region.