Oxidation of carbon/carbon (C/C) composites limits their applications as the high-temperature structural materials in aeronautics and aerospace fields. Coating is a logical method for protection of C/C composites against oxidation at high temperature. The research status of several oxidation resistant coatings, including glass, metal, ceramic and composite coatings are reviewed. Development of the traditional preparation technologies and exploitation of new methods for the preparation of oxidation resistant coatings are introduced. The present problems and the potential development direction on the investigation of oxidation resistant coatings for C/C composites are also proposed.

Carbon fiber reinforced paperbased friction material was prepared by paper-making process. The friction and wear performance of samples under repeated braking condition were investigated by a QM1000-Ⅱ wet friction performance tester.The scanning electron microscope and 3D non-contact surface profiler were employed to analyze the worn surface and understand wear mechanisms. Experimental results indicated that the friction torque curve became fluctuating and friction coefficient decreased with the increase of braking cycles, while wear resistance of the samples increased due to continuous friction film formed on the worn surface during the friction process.

The carbon/carbon composite wear particles generated from a hip joint simulator were separated. The size, morphology and thickness of the particles were tested by laser particle size analyzer, scanning electron microscope and 3-D profiler, respectively. The results show that the particles are 0.3-93.9μm in size and the morphology and the thickness of the particles distributes regularly according to their sizes. The particles whose sizes are larger than 30μm are carbon fibers with a constant thickness. The particles whose thicknesses are in a broad range with medium size (3-30μm) show irregular morphology and complex boundary. The particles whose thicknesses are in the range of submicrometers are less than 3μm in size and have a spherical or circular shape. Based on the experimental results, the evolvement of the wear particles in the wear process is explained.

45S5 bioactive glasses (BGs) were surfacemodified with dodecyl alcohol through esterification reaction to get 45S5/PDLLA composite films. The properties of the composite films before and after treatment in boiling water for 20min were investigated. The results show that water contact angles of the composite films decrease sharply after the boling water treatment, indicating the improvement of the hydrophilicity of the composite films. Furthermore, after boiling water treatment, the tensile strength of the composite films decrease slightly, and is still higher than that of 45S5 BGs/PDLLA composite films, which illustrate that the treatment in boiling water does not affect the homogeneous dispersion of BGs particles in PDLLA matrix. Most importantly, cells on the composite films after hydrolysis show the highest proliferation rate and differentiation level.

Pt_2Mo/C was prepared by microwavesynthesis to improve the catalytic performance of Ptbased catalysts towards methanol xidation. Effects of reaction and sonicating time on the crystal structure, micromorphology and electrocatalytic activity of Pt₂Mo/C were systematically investigated. The results show that the crystal structure of Pt₂Mo/C is mainly determined by the reaction time while the sonicating time has little influence on it. The micromorphology of Pt₂Mo/C is determined by oth the reaction and sonicating time. The influencing sequences of reaction and sonicating time on electrocatalytic activity of Pt₂Mo/C are 10min>15min>20min >5min and 60min>100min>30min>0min, respectively. The optimized parameters of preparing Pt₂Mo/C owing best catalytic activity towards methanol electrooxidation are 10min of reaction time and 60min of sonicating time.

Using Ti(OBu)₄ as titanium source, Agmodified TiO₂ was prepared by the microwave heating method and the hydrothermal ethod, respectively, and was characterized by Xray diffraction (XRD), Xray fluorescence (XRF), ultravioletvisible diffuse reflectance spectroscope (UV-Vis) and scanning electron microscope (SEM). The photocatalytic activity of the samples was tested in the degradation of gaseous toluene under UV and visible light irradiation, respectively. The results showed that the presence of Ag promoted the phase transformation of TiO2 from anatase to other phases. Compared with the hydrothermal method, the microwave heating method had more positive effect on the formation of Agmodified TiO₂ with smaller crystallite size (16.4nm) and aggregate (80-200nm), more phases structure (anatase, rutile and brookite), richer channel structure, and lower band gap energy (2.87eV). Furthermore, Agmodified TiO₂ prepared by the microwave heating method exhibited a better photocatalytic activity in the degradation of toluene under UV or visible light irradiation.

Micron size Cu/nanoTiO₂ composite particles were prepared in ambient conditions by bioinspired method. The surfaces of Cu particles were modified by a kind of amine, and the analysis of XPS indicated that the functional layer containing -NH₂ and -OH groups was formed on the surface of Cu particles through the coordination of nitrogen in the amine to Cu²⁺. Comparative experiment confirmed that -NH₂ and -OH groups induced the biomineralization of nano-TiO₂ on the Cu surfaces. XRD result showed that TiO₂ of anatase type was deposited on the surfaces of Cu particles. Results of diffuse reflectance spectra (DRS) showed that a weak absorption at 716.5nm occurred after Cu particles were modified by the amine, which indicated the coordination of N to Cu₂⁺. The photoabsorbance of Cu/nanoTiO₂ composite particles was between the photo-absorbance of TiO₂ and that of Cu. The optical absorption edge of the particles was extended from 397.5nm to about 448.9nm after Cu loading, because Cu loading introduces new mid gap level below the conduction band of TiO₂, and in this way the electron can be excited by visible light through the level. The absorption edge at 448.9nm indicated that Cu/nano-TiO₂ composite particles had the visible light catalytic activity.

Nanocrystalline TiO₂ powders were synthesized from TiCl₄ solution by the highpressure microwave method under pressure ranging from 0.1MPa to 4.0MPa. The phase structures, microstructures and photocatalytic properties of the nanocrystalline
TiO2 were investigated. It was found that the reaction pressure had a large impact on the phase structures, microstructures,
and photocatalytic properties of the nanocrystalline TiO₂. Under lower reaction pressure, TiO2 products consisted of anatase
and brookite phase, with the brookite phase in minority, while under higher reaction pressure, a large quantity of rutile
TiO₂ was formed. With the increase of reaction pressure from 0.1MPa to 4.0MPa, the average sizes of the TiO₂ nanoparticles
increased from 5nm to 30nm. At reaction pressures lower than 2.0MPa, the photocatalytic performance of the nanocrystalline
TiO₂ increased with the pressure, while at pressures higher than 2.0MPa, the photocatalytic performance was found to decrease
monotonically with the pressure.

TiO2 nanofibres, Y³⁺-doped and Nd³⁺-doped TiO₂ nanofibres were successfully fabricated by electrospinning using Ti(SO₄)₂,
polyvinyl pyrrolidone(PVP, Mr=1300000), rare earth oxides and dimethyl formamide(DMF) as raw materials. The samples were
characterized by XRD, FESEM, TEM, and TGDTA. XRD analysis indicated that RE/TiO₂(RE=Y, Nd) nanofibres with pure anatase
typed phase and pure rutiletyped phase were obtained by calcination of the relevant composite fibres at 550℃ and 900℃,
respectively, and the lattice parameters of TiO₂ were remarkably reduced by the doping rare earth ions. FESEM analysis
revealed that the average diameter of the RE/TiO₂(RE=Y, Nd) nanofibres was about 50nm, and their length was greater than 300
μm. Photocatalytic properties of the three nanofibres were investigated by degradation of rhodamine-B and phenol. The
results showed that the degradation rate of 1.5mol%Y/TiO₂ nanofibres was higher for rhodamine-B, while the degradation rate
of 1.0mol%Nd/TiO₂ nanofibres was higher for phenol. Therefore, the degradation activity of rare earth ions-doped TiO₂
nanofibres changed with the different doping rare earth ions and degradation compounds.

Deposition parameters are important to the characteristics of the Al_xGa_1-xNfilms. Effects of the deposition temperature on the defects densities and the photoluminescence of the Al_xGa_1-xN films with high Al content were investigated, which is deposited by low pressure MOCVD on sapphire. High resolution XRD, UVVisible transmittance, AFM, SEM, and photoluminescence spectroscope were used to characterize the Al_xGa_1-xN films with high Al content. It is found that as the growth temperature increases, the screw dislocation density in Al_xGa_1-xN films increases, while the edge dislocation density decreases. So simply increasing deposition temperature is not a good way to reduce the total defects density or enhance the photoluminescence of the high Al content Al_xGa_1-xN films. Further analysis shows that higher deposition temperature is beneficial to achieve high Al content Al_xGa_1-xN films. It’s found that as the deposition temperature increases, Al content in Al_xGa_1-xN films also increases, which results in the increase of the bandgap of the films. Therefore, moderately increasing the deposition temperature （1000-1050℃）is an effective way to increase Al content in Al_xGa_1-xN films. Nevertheless, too higher deposition temperature （>1100℃） is detrimental for the photoluminescence of the Al_xGa_1-xN films.

TiN_x films were prepared on Al2O3 substrates by laser chemical vapor deposition (LCVD). The effects of laser power (PL), pre-heatment temperature (T_pre) and total pressure in the main chamber (P_tot) on the orientation and deposition rate (Rdep) of TiNx films were investigated. The deposited TiNx films were characterized by Xray diffraction (XRD), atomic emission spectrometry (AES) and field emission scanning electron microscope (FESEM). The results showed that the composition in TiN_x films was uniform, and the orientation was relative to the T_pre, which changed from (111) to (200) orientation with increasing T_pre. The orientation was consistent with its microstructure. The Rdep of TiNx films increased with increasing P_L, showing a maximum (90μm/h) at P_L = 100W at a deposition area of about 300mm², which was higher than that of TiN_x films prepared by other methods.

Nanocrystalline NiFe₂O₄ powders were synthesized by citrate. Nitrate SolGel auto combustion method at room temperature. Various xerogels were obtained by adding different amounts of ammonia into precursor solution. The corresponding auto combustion powders were prepared through subsequent auto combustion process. The variation regularity of crystallinity of auto combustion powders, properties and thermal decomposition process of xerogel were investigated by XRD, TEM, IR and TG-DTA techniques. The mechanism of auto combustion method was further studied. The results indicate that auto combustion powders are mainly composed of NiFe₂O₄ phase with small amout impurity phase of α-Fe₂O₃ and FeNi3. The crystallinity of auto combustion powders are enhanced with increasing the amount of ammonia. The xerogel contains amorphous phase and NH₄NO₃ crystallization phase. The amount of ammonia exerts appreciable effects on the quantity of NH₄NO₃ and properties of xerogel. The mechanism of auto combustion is a chain reaction which is formed by mutual promotion of NH₄NO₃ decomposition and citric acid combustion.

Magnetic fluid of Fe₃O₄ was prepared via chemical coprecipitation method firstly, and then magnetic clinoptilolite with different loadings of Fe₃O₄
were prepared by clinoptilolite composited with magnetic fluid. The compositions were characterized by Xray diffraction (XRD), scanning electronic microscope (SEM), transmission electronic microscope (TEM) and vibration sample magnetometer (VSM). The magnetic recovery rate and saturation exchangeadsorption capacity to Cu²⁺, Zn²⁺, and Cd²⁺ of magnetic clinoptilolite were also measured. The results show that Fe₃O₄ particles adhere to the surface of clinoptilolite particles or aggregate each other to magnetic particulate. Magnetic clinoptilolite is stable with good superparamagnetism. The saturation exchangedsorption capacity to Cu²⁺, Zn²⁺, and Cd²⁺ are approximate with containing clinoptilolite, but decrease slightly along with the loadings of Fe₃O₄ increasing. When the loadings of Fe₃O₄ is 25wt%, the saturation magnetization and remanence magnetization of magnetic clinoptilolite is 14.787, 0.398 A·m²/kg, magnetic recovery rate is 94.6%, and saturation ion exchangeadsorption capacity to Cu²⁺, Zn²⁺, Cd²⁺ is 12.3, 12.0, 23.4 mg/g, respectively. The magnetic recovered clinoptilolite still retain superparamagnetism and high magnetic recovery rate after exposed in ambient for 100d.

Exfoliated graphite was separated into nanosized flakes by ultrasonication and acid treatment, and then FeCoNi alloy particles were deposited uniformly on the surface of flakes by codeposition method and annealing treatment process. Magnetic and microwave absorbing properties of the obtained samples were measured. The results show that the synthesized composites possess good soft magnetic performance and effective microwave absorption. The composite consisting of Fe₃Co₆Ni/graphite flakes annealed at 600℃ as an absorber has the maximum absorption value of -24dB at 12.6GHz, and the effective absorbing bandwidth (<-5dB) is about 8GHz. The characteristics of microwave absorption can be controlled by adjusting element ratios in alloy and the parameters of heat treatment process. This kind of composite has great potential and investigation value in microwave absorbing fields.

Cubic CrN nanoparticles with the size less than 10 nm were synthesized through direct reaction of metal Cr with N2 by arc discharge plasma method. The products synthesized under different nitrogen gas pressure were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and Fourier transform infrared spectra (FT-IR). The effect of N₂ pressure and accession of NH₃ on the formation of cubic phase CrN were studied. The results indicate that it is beneficial for the convesion of Cr to CrN under relative low N2 pressure (5~20kPa), namely more N atoms can diffuse into Cr lattice. Moreover, the accession of active nitrogen resource (NH3) weakens the nitridation of Cr.

The effects of traditional, multistep and two-step sintering technique on the microstructure and performance of high purity beryllium oxide ceramics were investigated. It was found that the grain size of 99BeO ceramics could be controlled by the multistep sintering method, and the thermal conductivity could be elevated via two-step sintering method. Moreover, the technique parameters of the twostep sintering method, such as the highest sintering temperature (T₁), the final sintering temperature (T₂) and holding time (t),were studied in detail. The results show that under the condition of T₁=1630℃, T₂=1550℃ and t=4h, 99 BeO oxide ceramics owing fine grain and compact structure were obtained with the thermal conductivity of 308W/(m·K), and the density of 2.95g/cm³.

Cr_2AlC bulk material was prepared insitu by hot pressing sintering using Cr₃C₂, Cr and Al as the starting materials. The samples were characterized using X-ray diffraction (XRD) and scanning electron microscope (SEM). The reaction process was investigated by means of differential scanning calorimetry (DSC). The corrosion properties of Cr₂AlC in the acid and alkali solutions were obtained by weight loss method. The XRD result shows that high purity Cr₂AlC bulk material can be synthesized by hot pressing with n(Cr₃C₂)∶n(Cr)∶n(Al)=0.5∶0.5∶1.2 at 1350℃ for 2h under 30MPa. The XRD patterns in different temperatures suggest that the reaction process of starting materials is that Al melts at first, then Cr5Al8 generates at 700℃, Cr₂AlC is produced with the temperature elevation by the reaction of Cr₅Al₈ and Cr₃C₂ at last. SEM images of fracture faces of the sintered sample show the laminated and well plateshaped grains with a mean particale size of 6.4μm. Cr₂AlC exhibits low weight loss except immersion in the concentrated H₂SO₄ and HCl solutions. The weight loss is negligible after immersing samples in the concentrated and dilute NaOH solutions for 150d and the corrosion rates are only 0.4 and 0.7μm/a, respectively.

Li₂O-B₂O₃-Al₂O₃ composite xerogels were successfully prepared from lithium methoxide, tri-nbutylborate and aluminum trisecbutoxide dissolved in methanol and tetrahydrofuran by SolGel method. The structure changes of xerogels upon increasing the Al
₂O₃ content and thermal treatment temperatures from 150℃ to 550℃ were characterized by FTIR and XRD. The results indicate that the relative content of BO₄ units shows a continuous decrease with increasing Al₂O₃ contents. Consequently, the concentration of asymmetric BO₃ units increase. The relative content of symmetric BO₃ units decrease. Total relative content of BO₃ units increase with the Al₂O₃ content increasing. The structure of the xerogel containing 10 mol%Al₂O₃ after heattreatment at 550℃ for 1h transforms from glassy to crystalline. The main crystalline is Li₂AlB₅O₁₀.

Tungstenlanthanumtellurite (TWL) glasses with the molar composition (90-x)TeO₂-xWO₃-9La₂O₃-1Tm₂O₃(x=10, 20, 30(mol%)) were prepared. Effects of WO3 contents on the thermal stability and spectroscopic properties of Tm³⁺ doped TWL glasses were studied. It is found that the thermal stability of TWL glasses is improved with the increasing WO₃ contents. For the glass with 30mol% WO₃, the glass transition temperature(T_g) is 457℃, while onset crystallization temperature(T_x) is not observed in DTA curve, and the thermal expansion coefficient of the glass decreases to 1.224×10^-5/℃ (30-300℃). The maximum phonon energy of the glasses shows the dependence on the host composition. The spectroscopic intensity parameters (Ω_t t=2,4,6), radiative transition rates, radiative lifetimes, and branching ratios are calculated by Judd-Ofelt theory. The emission crosssection of Tm³⁺: ³F₄→³H₆ transition is calculated by McCumber theory. The maximum emission crosssection of Tm³⁺ in 60TeO₂-30WO₃-9La₂O₃-1Tm₂O₃ glass is 9.6×10^-21cm². Evaluated from the thermal and spectroscopic properties, 60TeO₂-30WO₃-10La₂O₃ glass is a promising host material for ~2.0μm laser.

High quality Nd∶Lu₃Al₅O₁₂(Nd∶LuAG) crystal doped with 1at% Nd³⁺ was grown by the Czochralski method. The spectral properties of the crystal annealed in different atmosphere were characterized. The experiment indicates that the absorption band in 256nm, 467nm and 562nm are connected with Fe³⁺, O^-, and F⁺, respectively. The absorption cross section at 809nm is 1.86×10^-20 cm². The spectral parameters are calculated by JuddOfelt theory, and the intensity parameters Ω₂, Ω₄ and Ω₆ are estimated to be 0.71×10^-20cm², 1.13×10^-20 cm², and 4.36×10^-20 cm², respectively. The calculated radiative probabilities, branch ratios, radiative lifetime and emission cross section are evaluated for the ⁴F_3/2 excited state by using the calculated intensity parameters. The results indicate that Nd∶LuAG crystal is a promising material for solidstate laser application.

Cross-shaped SiC fibers were prepared from precursor polymer. The diameter of fiber’s circumcircle is about 34 μm, the length of vane is about 12μm, and the width of vane is 8μm. The complex permittivity and permeability of cross-shaped SiC fibers were measured by the coaxial line method at 2-18 GHz. The ε′, ε″, μ′, μ″ and tanδ of cross-shaped SiC fibers/paraffin wax composites are 2.77-7.93, 1.38-6.41, 0.96-1.12, -0.05-0.08, 0.49-0.81, respectively. Cross-shaped SiC fiber is a kind of dielectric loss materials. The reflection loss of the composites is below -10 dB at 9.12-18 GHz in the range of 2-18 GHz, and the minimum value is -28.47 dB at 12 GHz. The bandwidth corresponding to the reflection loss below -10 dB is 8.88 GHz.

AlNbO₄/mullite composite environmental barrier coating (EBC) with 5mol% AlNbO₄ content was prepared on Si₃N₄ substrate by atmospheric plasma spraying (APS). There was evidence that the weight loss rate of Si₃N₄ substrate coated by AlNbO₄/mullite composite was less than that of Si₃N₄ substrate coated by mullite during the first 50h corrosion test. The improved protective capacity of AlNbO₄/mullite composite coating was ascribed to the formation of glassy AlNbO₄ top surface. After 100h corrosion test, the AlNbO₄/mullite coating was still stable and no further corroded cavities were observed. However, slight delamination of the coating and a faster weight loss rate was observed after long time corrosion due to the coefficient of thermal expansion (CTE) mismatch between AlNbO₄/mullite composite and Si₃N₄ substrate.