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As a biomedical material，TC4 titanium alloy is widely used in the field of bone tissue repair in clinical practice，with annual consumption of about one million pieces in China.However，the properties of TC4 titanium alloy as low wear resistance and poor biological activity seriously restricted its expansion in engineering application.Therefore，a micro-arc oxidation/hydrothermal coating on surface of TC4 was fabricated by utilizing the micro-arc oxidation/hydrothermal synthetic composite technology，and the effects of La(NO3)3 doping amount in the hydrothermal synthesis solution on the phase composition，micro morphology，microhardness，wear resistance and other parameters of the micro-arc oxidation/hydrothermal coating on TC4 titanium alloy were surveyed.Moreover，the micro-arc oxidation/hydrothermal coating on TC4 titanium alloy was characterized by XRD，SEM，microhardness tester and friction and wear testing machine.Results showed that the micro-arc oxidation/hydrothermal coating on TC4 titanium alloy was mainly composed of anatase TiO2 and hydroxyapatite.After hydrothermal treatment，La3+ in the synthetic solution entered the composite coating and participated in the coating reaction.With the increase of La(NO3)3 doping amount，the content of hydroxyapatite phase in the composite coating increased first and then decreased.When the doping amount of La(NO3)3 exceeded 24 mmol/L，the coating surface became smoother.In addition，the microhardness of micro-arc oxidation/hydrothermal composite coating on TC4 titanium alloy decreased first and then increased，and the friction coefficient increased first and then decreased.As the doping amount of La(NO3)3 reached 24 mmol/L，microhardness of the composite coating on TC4 titanium alloy acquired the minimum value，and it was about (271.8±3.1)HV9.8 N，the friction coefficient of the composite coating obtained the maximum value，and it was about 0.8～0.9.

Infiltrated molten Al matrix by mechanical-pressure infiltration method into the ceramic scaffold prepared by freeze-drying technology could prepare dense lamellar Al matrix composites without damage of the biomimetic microstructure of the scaffold. However, the investigation of lamellar Al matrix composites prepared by freeze-drying and mechanical-pressure infiltration method has not been fully understood yet. In the present work, the Al2O3 scaffold with pearl layer structure was prepared by freezing-dry method, and eventually the lamellar Al2O3p/Al composite was fabricated by mechanical-pressure infiltration method. The Al matrix was infiltrated well into the large pores of the Al2O3 scaffold, and the lamellar structure of the Al2O3 was well preserved. The hardness of the lamellar Al2O3p/Al composite was isotropic in transvers and perpendicular directions. However, the compressive strengths of the lamellar Al2O3p/Al composite were significant anisotropic while the compressive strength in transvers direction was 127.7% higher than that in the perpendicular direction, indicating the integrality of the lamellae microstructure (especially the bridging layers). Due to the mismatched deformability, weak debonding was observed between Al and Al2O3p/Al layers in the fracture surface of the lamellar Al2O3p/Al composite. It indicates that the interfacial bonding between Al and Al2O3p/Al layers is rather strong, which is beneficial for higher strength in transvers direction but lead to lower strength in perpendicular direction. [ABSTRACT FROM AUTHOR]

Graphene platelets reinforced zirconia ( GPLs/ZrO2) composites were prepared by spark plasma sintering in the present work. The effects of GPLs content on the densification route, microstructure feather, mechanical properties, and aging behaviors of such composites were investigated. In spite of the impeding effect of GPLs, high relative density of 98% was achieved for the composites owing to the uniform dispersion of GPLs. The addition of GPLs contributed to enhanced fracture toughness of the composites; when the added content was 1.0 wt.%, its fracture toughness reached up to 8.6 MPa·m1/2. Also, aging behavior of the GPLs/ZrO2 composites was investigated at 134°C for 24 hours. The monolithic ZrO2 ceramic and GPLs/ZrO2 composites presented residual ratio of 55% and 72% in fracture toughness, respectively. Thus, the incorporation of GPLs inhibited phase transformation from tetragonal phase to monoclinic phase of zirconia. [ABSTRACT FROM AUTHOR]

A transparent TiO 2 -C@TiO 2 -C free-standing film has been synthesized by two-step hydrothermal method and subsequent thermal annealing. The chemical composition and morphological features of the TiO 2 -C@TiO 2 -C film are characterized using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and N 2 adsorption-desorption measurement. The results indicate that the flower-like micro/nanostructure TiO 2 -C particle layers are intimately inhered to porous TiO 2 -C fibers. The fibers in film are interconnected each other to form a three-dimensional reticulate microstructure, and exhibit intense visible light absorption and high adsorptivity of dye molecules. The interaction between TiO 2 and its surface carbon layer in TiO 2 -C particle promotes the generation of Ti- O -C bonds, which leads to effective charge transfer. Under visible-light irradiation, TiO 2 -C@TiO 2 -C film presents enhanced photocatalytic activity for degradation of methylene blue. This work may provide a new viewpoint for designing transparent photocatalytic film for promising applications in heterogeneous photocatalysis. [ABSTRACT FROM AUTHOR]

As a focus of research on materials science, bionic structure has drawn a great deal of attention from researchers. In this paper, patterned antireflection microstructure used for space optical window was fabricated on the surface of sapphire single crystal based on “Biomimetic Motheye Structure”. Meanwhile, emissivity of patterned sapphire at high temperature was investigated. The results indicated that transmittance of sapphire increased with spectrum red shift effect because of surface microstructures; the emissivity of patterned sapphire increased with rising of temperature in 6∼11 μm band; microstructures on surface led the scattering and attenuation coefficient of light to increase, thus, the emissivity of patterned sapphire was greater than that of contrast specimen which was not patterned. At the end of the paper, an audacious conclusion was made that the effect of microstructure on emissivity would decrease or even disappear with the increase of temperature. [ABSTRACT FROM AUTHOR]

Abstract: Crosslinked carbon network with interconnected pores were obtained from [furfuryl alcohol (FA) + phenol–formaldehyde resin (PF)] – ethylene glycol (EG) mixtures. The effect of FA/PF weight ratio (W F/P) on the pore structure of the porous carbons has been systematically investigated. The results showed that porous carbons with controlled pore size could be obtained by varying W F/P in the polymer system. With W F/P increased, the average pore size and apparent porosity increased from 11.8 to 127.7 nm and from 40.9 to 51.6%, respectively, and the pore size distribution broadened. The property change of the porous carbons was a result of polymerization dynamics change on curing of resin–glycol mixtures induced by varying W F/P in the polymer system. Increasing the initial W F/P led curing reactions to occur at relatively lower temperatures, and the degree of polymerization to increase after heat treatment at 150 °C for 16 h, thus cured bodies with different chemical structures were obtained. [Copyright &y& Elsevier]

Abstract: Variation of microstructure and mechanical behavior was investigated with the content increase of carbon particles and carbon fiber in the reaction bonded silicon carbide composites. The composites were prepared by slip casting and liquid silicon infiltration. The bulk density is raised with the increase of carbon black due to the formation of fine β-SiC particles. The flexural strength increases for the reduction of residual Si and the formation of SiC framework; whereas a very high carbon content reduces the flexural strength. The fracture toughness is controlled by the contents of carbon particle and carbon fiber. Thus, fiber debonding, fiber pullout and crack deflection are considered as the main toughening mechanisms. Annealing treatment can effectively improve both the flexural strength and fracture toughness. An increase by 49% of fracture toughness is obtained. A series of structural models are proposed to illustrate the structure changes of carbon fiber. [Copyright &y& Elsevier]

Abstract: Nano-sized zirconia particles were dispersed in a SiC/C suspension to examine the particle influence on microstructure and mechanical properties on the resulting composite. The ZrO2/reaction bonded SiC composite was produced by a combination of slip casting and liquid silicon infiltration. By dispersing zirconia particles into the matrix, the gowth of β-SiC was inhibited and the size of residual silicon was reduced. This result led to an increase of flexural strength with reinforcement ranging from 0 to 20wt.%. Compared with the monolithic RBSC ceramics, the fracture toughness was steadily improved, reaching the peak value of appropriate 4.6MPam1/2 at the zirconia fraction of 25wt.%. The XRD analysis revealed the phase transformation occurred on the fracture surface of the composites. Thus, the transformation of zirconia and the crack deflection are considered as the main toughening mechanisms. [Copyright &y& Elsevier]

Abstract: The porous ZrO2 ceramics with ultra-high porosity were produced by combining phase change, heat exchange and freeze drying process of ZrO2 slurries during decompression environment. The prepared slurry was first cooled to near the supercooling point, and then the supercooled slurry was placed on decompression system to induce foaming and solidification until the decompress-freezing process of the slurry completed. After drying and sintering of the green part, an as-prepared ceramic with porosity more than 93% was obtained. It was shown that the porous ceramic was typically composed of large spherical cells, interconnected by near circular windows. Although the mechanical properties in obtained ceramics are not enough to resist high stress, porous ceramics with a number of pores in cell walls and struts may be expected to be applied in high thermal insulation process. [Copyright &y& Elsevier]

Abstract: This paper deals with the microstructure and mechanical properties of reaction bonded silicon carbide reinforced with random chopped carbon fibers of 3mm length. The composites were fabricated by dispersing chopped carbon fibers into bimodal SiC/C suspension, forming green body through slip casting, and then reaction sintering at 1700°C. The effect of the chopped fiber fraction on microstructure and mechanical properties was evaluated. A significant increase of fracture toughness was obtained as the carbon fiber fraction approaches 30vol.%. The chopped fibers had reacted with liquid silicon during reaction sintering, so little fiber pullout was observed. Crack deflection and bridging is the predominant mechanism for the composite toughening. [Copyright &y& Elsevier]

Abstract: CaTiO3 ceramic powder filled polytetrafluoroethylene (PTFE) composites with various filler volume fractions up to 60vol.% were prepared. The effects of volume fraction of the ceramic filler on the microstructure and microwave dielectric properties of the composites were investigated in detail. As the volume fraction of the ceramic filler increases, the dielectric constant (ɛ r) and the temperature coefficient of resonant frequency (τ f) of composites increase, while the product of quality factor and frequency (Q × f) decreases. Composites with 40vol.% CaTiO3 exhibited good microwave dielectric properties: ɛ r =13 at ∼5GHz, Q × f =930GHz, and τ f =260ppm/°C. Different mixing rules were used to predict the dielectric constant of composites, and it was found that the dielectric constants predicted by Effective Medium Theory (EMT) were in good agreement with experimental data. [Copyright &y& Elsevier]

Abstract: Experiments have been performed to show that the mechanical properties of alumina porous ceramics may be improved by introducing glycerol into the raw slurries and then casting them under a constant cooling rate. The effects of glycerol on the freeze casting process and thereby on the microstructure and mechanical properties of porous ceramics obtained are investigated. It is shown that the addition of glycerol will increase both the slurry viscosity and sample sintered density. SEM images for microstructure of the final ceramics reveal that a good connection between ceramic lamellae has been promoted. This connection makes as-prepared porous ceramics obtain high mechanical properties. For the 30vol.% alumina slurry with glycerol, the axial and radial compression strengths reach to, respectively, 255.1MPa and 105.8MPa. [Copyright &y& Elsevier]

Abstract: Porous carbons were prepared from resin mixtures containing furfuryl alcohol (FA) and phenolic-formaldehyde resin (PF) as the carbon precursors. The effect of FA/PF mass ratio on the pore structure of the porous carbons was systematically investigated. Crosslinked carbon network could be obtained with the mass ratio of FA and PF changing from 0:10 to 3:7. With increasing FA content in the mixtures, the pore size distribution of carbon monoliths broadened, and the average pore size and apparent porosity of the carbonized products increased from 11.8 to 127.7nm and from 40.9% to 51.6%, respectively. The morphological and pore structure change of the porous carbons was a result of polymerization kinetics change induced by varying the FA/PF mass ratio in the polymer system on curing of initial resin compositions. Increasing FA/PF mass ratio led increased atomic order to occur in the amorphous structure. [Copyright &y& Elsevier]

Hexagonal V-pits with an inverted pyramid shape appear on the surface of a GaN film after etching by hot H 3 PO 4 . A regular structure that is different from the V-pit morphology is observed in the cathodoluminescence image. The carrier concentration and stress distributions are nonuniform inside the V-pit. Furthermore, no dominant dislocations or defects are observed in the facets or bottom area of the V-pits. An island coalescence process is considered to contribute to the formation of such V-pits, with the coalesced island facets changing from {1 0 1 m} to {1 1 2 m} at a concave state for the different growth velocities. [ABSTRACT FROM AUTHOR]

A nanofiber-based TiO 2 (B)/carbon nanofiber membrane has been synthesized by a facile and effective route that incorporates electrospinning approach with hydrothermal method. The prepared membrane shows high flexibility and hydrophilicity. After treatment with a low surface energy fluorosilane, the obtained superhydrophobic surface endows the membrane a high adhesive force due to the hybrid microstructure of TiO 2 (B) nanotubes and nanoplates on fibers. A water droplet on the surface of the membrane appears spherical in shape, which cannot roll off even when the membrane is bent and turned upside down. When a water droplet dropped from a certain height above the tilt membrane, the rolled water droplet can be stopped after a small displacement. In addition, a 12 μl water droplet can be quickly captured from a hydrophobic surface by curvature change of the superhydrophobic TiO 2 (B)/carbon nanofiber membrane. The membrane with excellent static and dynamic pinning performance to water may be expected to apply to biomedical and microfluidic devices. [ABSTRACT FROM AUTHOR]

Abstract: TiO2/carbon paper composite materials with a hierarchically porous structure were synthesized by employing a filter paper as the support material and carbon source. The resorcinol–formaldehyde–block copolymer nanocomposite formed by the self-assembly of phenolic resin and F127 under acidic condition was selected as modifier of the microstructure of carbon paper. Results show that the as-adjusted carbon paper preserved the nanostructure of a pure carbonized filter paper. An ordered mesostructure was also formed. This micromorphology resulted in the increased specific surface area, as well as micropore and mesopore volumes, compared with the pure carbonized filter paper. When mesoporous TiO2 was deposited on the carbon paper with ordered mesopore by the evaporation-induced self-assembly route, the TiO2/carbon paper composite materials displayed excellent adsorption property and enhanced photocatalytic activity of methylene blue. [Copyright &y& Elsevier]

Two hierarchically porous silica ceramics with unidirectionally aligned channel morphology have been in situ synthesized by using soluble starch monoliths with well-defined uniaxial macroporous structure as template. Both these ceramics faithfully inherit the structure of soluble starch templates and show a large BET surface as well as a microstructure of uniform worm-like nanopores and a lamellar phase. These materials may be suitable for use in various separation and reaction processes. [Copyright &y& Elsevier]

Axially aligned fibrous monolithic ceramics present non-catastrophic fracture behavior via crack deflection and delamination along cell boundaries. However, severe in-plane anisotropy and time-consuming preparation procedures prevent their extensive promotion. The introduction of high content of weak phase components with poor oxidation resistance in weak interface destroys the excellent oxidation resistance of ceramic matrix. In this work, ZrB 2 -based short fibrous monolithic (SFM) ceramics with in-plane isotropic mechanical properties and excellent oxidation resistance were easily prepared by hot pressing randomly assembled short ceramic fibers. The microstructure and mechanical behavior of ZrB 2 -based SFM ceramics densified at various temperatures were systematically investigated. The mechanical properties of ZrB 2 -based SFM ceramics slightly improved with the increase of sintering temperature. ZrB 2 -based SFM ceramics exhibited excellent oxidation resistance and remained intact without macroscopic cracks after ablation for 615 s in oxyacetylene flame with maximum temperatures exceeding 2150 °C. The oxidation behavior was analyzed in detail. [ABSTRACT FROM AUTHOR]

Continuous silicon carbide fiber–reinforced silicon carbide matrix composites (SiC f /SiC) are promising candidate materials for nuclear applications. In this paper, three–dimensional SiC f /SiC composites were fabricated using polymer infiltration and pyrolysis method. Interface properties of SiC f /SiC composites that were irradiated with 3 MeV Si ions to 1 dpa and 5 dpa at room temperature were studied using single-fiber push–out test, Raman spectroscopy, and transmission electron microscopy. Results indicate that, after being irradiated with different doses of Si ions, SiC f /SiC composites have weaker interfacial shear strength compared to that of samples before irradiation. The greater that the ion irradiation damage is, the lower that the interfacial shear strength is. With an increase in ion irradiation dose, the strength of the disordered (D) and graphitic (G) characteristic peaks in Raman spectra of SiC f /SiC composite decreases, and full width at half–maximum broadens. TEM micrographs show that ion irradiation damaged the continuity of SiC f /SiC composites, and microcracks appeared at pyrocarbon interface between the fiber and matrix. The crystallinity of SiC was lowered, the grain size shrank, and the ordered C phase became amorphous noncrystalline structure. [ABSTRACT FROM AUTHOR]

The constitutive behavior of aluminum alloy 7075 was characterized using compression tests performed over a wide range of temperatures (350–600 °C, from warm deformation temperature to semi-solid region) and strain rates (10 −3 –1 s −1 ). This work is of significance for the development of compound forming which combines plastic forming and semi-solid processing. The constitutive behavior in the wide temperature range was divided into two types: plastic deformation when the alloy is in solid state and containing a small fraction of liquid (350–490 °C); thixotropic deformation when the alloy is in the semi-solid state (above 490 °C). An adjusting factor which denotes the effect of liquid on the constitutive behavior was proposed. The constitutive model of peak stress as a function of temperature and strain rate was obtained for the wide range of temperatures (350–600 °C). The average relative errors between the calculated and measured values are 3.88% (350–490 °C) and 4.189% (above 490 °C), respectively. [ABSTRACT FROM AUTHOR]

Abstract: TiO2 nanoparticles were prepared using a surfactant (linoletic acid (LA) or polyethylene glycol-400 (PEG-400)) at various hydrolysis ratios (R=H2O/C2H5OH) by the hydrothermal method and studied for photocatalytic degradation of rhodamine B (RhB) under visible light irradiation. Special shapes of TiO2 nanoparticles, such as cubic, hexagon, bipyramid, and bullet, were found from the use of PEG-400 during the preparation. The cause for the formation of these special shapes is also discussed here. Interestingly, the hydrolysis ratios affected the Brunauer–Emmett–Teller (BET) special surface areas of the TiO2 nanoparticles. Owing to the effects of the surfactant PEG-400 on the microstructures, the resulting materials exhibited relatively higher photocatalytic activity than conventional TiO2 nanoparticles in the presence of LA. Furthermore, P-TiO2-8/10 (P is PEG-400 and 8/10 is H2O/C2H5OH molar ratio) nanoparticles had a similar photocatalytic activity to P25 and TiO2-10/10. [Copyright &y& Elsevier]