Al-doped ZnO (AZO) powders were prepared by using metal chloride precursors and the sol-gel technique. IR peaks observed at 1590 cm^-1 and 1620 cm^-1 indicated the formation of metal chelate as a consequence of the addition of acetylacetone to the metal chloride solution. TG-DSC analysis of the AZO gels confirmed the formation of metal chelate as evidenced by the development of several weight loss peaks accompanied by the introduction of new endothermic peaks. The resulting AZO gels were annealed at 500, 600, and 800 °C to study the effect of annealing temperature. XRD and SEM results showed that crystallization of AZO gels takes place around 600 °C. Hexagonal wurtzite structure was identified as the main phase for all the samples. In addition, small shift of the XRD (002) peak coupled with XPS results from the AZO powders confirmed the successful doping of the ZnO powders. Micron sized rod-like AZO powders were uniform in dimension and morphology and remained stable even at 800 °C.

The presents preparation and characterization of different types of lignocellulosic fillers (pine wood sawdust/ walnut shell flour/ black rice husk powder) reinforced polypropylene composites were presented. The effect of MAPP as coupling agent (4wt%) on the physical and mechanical properties was also investigated. Polypropylene composites were prepared at different rates of filler/matrix (wt%) by using extrusion (for melt blending) and hot compression molding process. Maximum values of tensile and flexural strength were obtained as 26.1 and 43.4 MPa, respectively, whereas the elongation at break value was 4.11% at 10% pine wood sawdust reinforced PP. Tensile and flexural modulus of composites reached the maximum values as 3855 and 3633 MPa with the composite of 30% walnut shell flour reinforced PP. Characterization of composites was carried out by using tensile test, flexural test, FT-IR, and SEM.

Polydimethylsiloxane (PDMS)-polystyrene (PS) interpenetrating polymer network (IPN) was prepared and characterized by FTIR, TGA, WCA, swelling experiments, and SEM. The IPN was used for pervaporation (PV) recovery of butanol. Both the permeation flux and separation factor increased with feed temperature, and both water and butanol fluxes increased with feed concentration, while no obvious effect of concentration on separation factor was found. Through the formation of IPN structure, the total flux of PDMS-PS IPN pervaporation membrane increased greatly with the decrease of separation factor. At the feed temperature of 60 °C, the IPN membrane obtained a total flux of 920.3 g/m²h with a separation factor of 9.5.

MoO₂ nanocrystals (NCs) on Ni foam were simply synthesized via a facile hydrothermal method and a dip-coating method. It was worth noting that ultrafine interconnected MoO₂ nanocrystals (about 10 nm) were uniformly anchored on Ni foam to fabricate a particular three-dimensional architecture, which may provide more active sites and shorter transmission pathways for lithium ions. As binder-free anode, MoO₂ NCs on Ni foam deliver a high initial discharge capacity of 990 mAh·g^-1 and retain a reversible capacity of 924 mAh· g^-1 after 100 cycles at a current density of 0.1 C. More importantly, when the current density returns from 2 C to 0.1 C, the capacity recovers to 910 mAh·g^-1 (about 92% of the original high capacity), suggesting excellent cycling stability and rate capability. The particular 3D electrode as binder-free anode makes it a promising anode candidate for high-performance lithium-ion batteries.

The effects of circulating fluid bed (CFB) ash on the adsorption performance of polycarboxylate superplasticiser and the mechanism of this influence on the dispersive property of the polycarboxylate superplasticiser were investigated by determing the cement paste fluidity, total organic carbon adsorption, infrared spectroscopic analyses and ζ potential test. The experimental results show that the addition of an inorganic salt into the mixture to change the content of SO₄ ^2- and Fe₂O₃ can improve the adaptability between the CFB ash and polycarboxylate superplasticiser. Adsorption may occur between the polycarboxylate superplasiciser and Fe₂O₃, SO₄ ^2- or other components in CFB ash, leading to a significant reduction in paste fluidity. As the content of Na₂SO₄ in CFB ash reaches 3% or Fe₂O₃ reaches 9%, the paste loses its liquidity. The organic carbon content in the liquor decreases with an increase in Na₂SO₄ or Fe₂O₃ content. Adding some Ba(NO₃)₂ and Na₂S to the liquor can recover the organic carbon content to a certain extent, and the absolute value of ζ potential will increase. The addition of Ba(- NO₃)₂ or Na₂S reduces the adsorption property of Na₂SO₄ or Fe₂O₃ in CFB ash on the polycarboxylate superplasticiser.

Taking dodecanethiol as the representative, we investigated the corrosion inhibition performance of SAL in seawater under pressures from 0.1 to 9 MPa. By using scanning Kelvin probe, the dodecanethiol SAL is confirmed to build on Cu surface, and the modification of SAL has positively shifted the surface potential to realize the inertness. Electrochemical techniques, such as electrochemical impedance spectroscopy and potentiodynamic polarization were used to reveal the corrosion behavior of Cu modified by SAL under the different pressure, i e, 0.1, 3, 6, and 9 MPa. It is indicated that the longer modification time affords better corrosion resistance to Cu. Higher static pressure is easier to deteriorate the corrosion inhibition capability due to the penetration effect. A plausible mechanism is proposed to illustrate the degradation process of SAL in the high pressure seawater environment.

In order to investigate the effect of the thickness on the electrical conductivity of yttria-stabilized zirconia (YSZ) film, the nanocrystalline columnar-structured YSZ film with thickness of 0.67-2.52 μm was prepared by magnetron sputtering through controlling the deposition time. All the sputtered films with different thicknesses consist of the main phase of cubic YSZ as well as a small amount of monoclinic YSZ. The thicker films exhibit a typical columnar grain structure based on the fractured cross-sectional SEM observations. The average diameters of columnar grains increase from about 40 nm to 100 nm with the film thickness from 0.67 μm to 2.52 μm according to TEM analysis. The thinnest YSZ film with 0.67 μm thickness shows the highest apparent electrical conductivity in the four films in 400–800 °C due to the contribution from the highly conductive film/substrate interfacial region. On the other hand, the real electrical conductivities of YSZ films increase with film thickness from 0.67 μm to 2.52 μm after eliminating the contribution of the film/substrate interface. The increasing film thickness leads to the grain growth as well as the decrement in the volumetric fraction of the resistive columnar grain boundary and a consequent higher real electrical conductivity.

Strontium titanate (SrTiO₃) submicron-fibers with perovskite structure were successfully synthesized by electrospinning method. The nanomechanical properties of synthesized SrTiO₃ were investigated by the novel amplitude modulation-frequency modulation (AM-FM) method based on atomic force microscope and nanoindentation technique. The results of AM-FM show that the resonant frequency of SrTiO₃ submicron-fiber is lower than that of the Si substrate, which indicates that the Young’s modulus of SrTiO₃ submicron-fiber is smaller than that of Si substrate in the range of 105–125 GPa. Nanoindentation further confirmed the results, showing a value of 104 ± 17 GPa. The atomic force microscope-based AM-FM provides us a new way to study the mechanical performance of low dimensional materials.

A comprehensive investigation was made on the electronic structure, thermal expansion coefficient and light absorption spectrum of total six transition metal dichalcogenides (TMDs) compounds with formula of MX₂ (M=Mo, W, Cr, X=S, Se). First, an indirect-direct band gap transition from bulk to singlelayer was declared for all the six compounds. Moreover, the detailed lattice constants and thermal expansion coefficients provided in the paper were the key information for designing MX₂-based field effect transistors. Finally, the calculated optical absorption spectra demonstrate that these compounds can effectively utilize solar energy and are good photo catalyst candidates. All these present findings will benefit the design of new generation of novel two-dimensional materials.

The (001) oriented BiFeO₃ thin film was deposited on the Nb: SrTiO₃ substrate by radio frequency magnetron sputtering technology, and the bipolar resistive switching effect was observed in the BiFeO₃/Nb: SrTiO₃ heterostructure. The results showed that the ratio between the high resistance and low resistance was more than two orders at a reading pulse of -0.5 V and it exhibited excellent retention over 3600 s. The current density-voltage characteristic was dominated by the space-charge-limited conduction. The resistive switching effect of the structure was attributed to the trapping/detrapping of the charge carriers.

We studied the characteristics of two-scale pore structure of preform in the deposition process and the mass transfer of reactant gas in dual-scale pores, and observed the physiochemical phenomenon associated with the reaction. Thereby, we established mathematical models on two scales, respectively, preform and reactor. These models were used for the numerical simulation of the process of ceramic matrix composites densified by isothermal chemical vapor infiltration (ICVI). The models were used to carry out a systematic study on the influence of process conditions and the preform structure on the densification behaviors. The most important findings of our study are that the processing time could be reduced by about 50% without compromising the quality of the material, if the processing temperature is 950–1 000 °C for the first 70 hours and then raised to 1 100 °C.

In the absence of commonly used seed layer, we can still successfully synthesized aligned ZnO nanowire arrays by the hydrothermal method. By using aluminum-doped zinc oxide (AZO) glass as a substrate, high-density and vertically aligned ZnO nanowires were synthesized directly on the substrate in the absence of the ZnO seed layer. The current-voltage curve indicated that the sample grown on AZO glass substrate in the absence of seed layer possesses better conductivity than that synthesized on FTO glass substrate with ZnO seed layer. Thus, a simplified, seed-free and low-cost experimental protocol was reported here for large-scale production of high quality ZnO nanowire arrays with promoted conductivity.

In order to fabricate a novel ZnO/cotton composite, a high proportion of ZnO nanoparticles were assembled in cotton fibers, and the as-obtained cotton fabric can possess better UV blocking property compared with common ZnO/cotton composite. Firstly, the cotton fibers were pre-treated by hydrogen peroxide solution(H₂O₂) and sodium hydroxide(NaOH), urea(CON₂H₄). Secondly, the fabric was fabricated via in situ deposition. The effects of concentration of treatment liquid, ammonia-smoking time and curing temperature on the tensile property of the fabric, UV blocking property and water-washing durability test of as-obtained cotton fabrics were investigated. Thirdly, the as-obtained cotton sample was characterized by X-ray diffraction(XRD) and field emission scanning electron microscopy(FESEM). It was shown that ZnO nanoparticles were assembled between cotton fibers, the surface and inside of the lumen and the mesopores of cotton fibers, while the content of nano-ZnO assembled in fabric can reach 15.63wt%. It is proved that the finished fabric can obtain a very excellent UV blocking property, under the condition of zinc ion in concentration of 15wt%, ammonia-smoking time for 10 min, curing temperature at 150 °C for 2 min.

Powder quartz (PQ)/nano-TiO₂ composite was prepared by a mechanochemical method. Based on as-prepared PQ/nano-TiO₂ composite, we prepared interior paints and investigated the degradation efficiency of formaldehyde (DEF). Scanning electron microscopy showed that nano-TiO₂ got well dispersed by the adding of PQ. Thermogravimetric analysis indicated that the mass ratio of 4:1 was a relatively good proportion for the most production of PQ/nano-TiO₂ composite. Fourier transform-infrared spectrometry showed that the peak position of Ti-O-Si bond varied with the milling time. At the early stage, no characteristic peak of Ti-O-Si bond was observed, while at the later stage, new peaks at 902 cm^-1 and 937 cm^-1 appeared. Meanwhile, PQ/nano-TiO₂ composite-based interior paint exhibited significant DEF of 96.3% compared to that consisting of sole nano- TiO₂ of 92.0% under visible light illumination. As an abundant mineral resource, PQ would make interior paints with HCHO purifying effect much more efficient and cheaper.

The magnetically separable ternary polyetherimide/titanate@Fe₃O₄ (PTF) photocatalysts of special heterostructure between magnetite (Fe₃O₄) microspheres and titanates nanosheets modified by polyetherimide (PEI) were successfully fabricated via a simple facile hydrothermal deposition method. The as-prepared photocatalysts were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, Transmission electron microscopy and UV-vis diffuse reflectance spectroscopy etc. The results showed that the as-fabricated material had a structure of Fe₃O₄ microspheres coated with titanates nanosheets modified by PEI. The special interfacial contact between 3D microsphere and 2D nanosheets in the nanoarchitectures was formed via electrostatic attraction. Furthermore, the resulted photocatalysts were tested by degradation reaction of methylene blue under visible light irradiation and demonstrated an enhanced performance than the pure Fe₃O₄ microspheres, and the photocatalytic activity enhanced with the molar ratio of Fe₃O₄ microspheres and modified titanate gradually, which was attributed to the expansion of the surface area and the different electrostatic contact between the Fe₃O₄ microspheres and titanate nanosheets. Moreover, the obtained results revealed the high yield magnetic separation and efficient reusability of PTF-5 (96.7%) over 3 times reuse.

Functionalized graphene nano-platelets (FGN) were obtained via treating graphene nanoplatelets (GN) with HNO₃, and served as adsorbent for the removal of Pb²⁺ from solutions. We investigated the FGN adsorption capacity for Pb²⁺ at different initial concentrations, varying pH, contact time and temperature. The characterization results of scanning electron microscopy (SEM), thermal analysis (TG/DTG), Fourier transform infrared spectroscopy (FT-IR) and Brunauer-Emmett-Teller (BET) method indicated that FGN layers were thin and possess large specific area with oxygen-containing functional groups grafted onto their surface. Meanwhile, the determined equilibrium adsorption capacity of FGN for Pb²⁺ was 57.765 mg/g and adsorption isotherms well confirmed to Langmuir isotherms models. The results reveals that the FGN has better effect of water treatment.

Using plasma build-up welding technology, Ni60, WC, Cr₃C₂, and TiC composite powders were clad on the surface of the substrate in a certain proportion according to the metallurgical bonding method to increase the bond strength between the coating and the substrate. Scanning electron microscopy and energy dispersive spectroscopy were used to observe the microstructure of the surfacing layer and the chemical composition of the sample. The hardness and wear resistance of the surfacing layer were tested and analyzed by the HV-1000 hardness tester and the impact wear device. The results showed that in the microstructure, fishbone, spider-web, and floral-like structures appeared in the surfacing layer. When the micro-hardness was tested, the depth of the indentation reflected the hardness of the surfacing layer. When analyzing wear resistance, the amount of wear increases with time.

Calcium sulfate hemihydrate whiskers were synthesized successfully via one-step hydrothermal crystallization method using phosphogypsum at 130 °C for 240 min with an initial slurry mass fraction of 2.5wt%. The phase compositions, microstructures, thermal properties and molecular structures of asprepared samples were analyzed by XRD, ESEM, EDS, TG-DTA, and FT-IR. The influence of raw materials’ ball-milling time on the morphologies of whiskers was investigated. The effects of impurities on crystallization morphologies and length to diameter ratio (L/D) of calcium sulfate hemihydrate whiskers were studied. The results indicated that the calcium sulfate dihydrate crystalline could be translated directly into fibrous calcium sulfate hemihydrate whiskers. It was beneficial to form fine fiber structure when the ball-milling time of the raw material was 15 min. Aspect ratio of calcium sulfate hemihydrate whiskers decreased with increasing content of impurities. Moreover, the relative growth mechanism of whisker crystals via one-step hydrothermal crystallization method was discussed in detail.

The effect of thermal wave at the initial stage for non-conductive Al₂O₃ powders compact in field assisted sintering technique (FAST) was investigated. The Lord and Shulman type generalized thermoselastic theory was introduced to describe the influence of thermal-mechanical interaction, as well as the heat transport and thermal focusing caused by thermal wave propagation. The expression of vacancy concentration difference of the particles was deduced by considering transient thermal stress. Subsequently, the relationship between activation energy and vacancy concentration difference was obtained. The mechanism of surface diffusion, volume diffusion, simultaneous surface and volume diffusion was analyzed. The numerical simulations indicate that low sintering temperature can obtain high local temperature by the superposition effect of thermal wave. Vacancy concentration differences were improved during FAST compared with hot-pressure and pressureless sintering, thereby decreasing the sintering time. By contrast, the activation energy declined with the decrease of vacancy concentration difference in the neck growth process.

Single-crystal Fe₃O₄ with monodisperse microspheres structure has been used for individual electrochemical detection of heavy metal ions. Morphology and structure of the as-prepared Fe₃O₄ microspheres were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). Meanwhile the electrochemical properties of the Fe₃O₄ microspheres modified glass carbon electrodes (GCE) were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), and the enhanced electrochemical response in stripping voltammetry for individual detection of Pb(II), Hg(II), Cu(II), and Cd(II) was evaluated using square wave anodic stripping voltammetry (SWASV). With high specific surface area and excellent catalytic activity toward heavy metal ions, the as-prepared monodisperse and single-crystal Fe₃O₄ microspheres show a preferable sensing sensitivity (22.2 μA/μM) and limit of detection (0.0699 μM) toward Pb(II). Furthermore, the electrochemical sensor of Fe₃O₄ microspheres exhibits excellent stability and it also offers potential practical applicability for the determination of heavy metal ions in real water samples. This study provides a potential simple and low cost iron oxide for the construction of sensitive electrochemical sensors applied to monitor and control the pollution of toxic metal ions.

SPES/PVDF blends were employed to prepare the ion exchange membranes for vanadium redox flow battery (VRB) application for the first time. The addition of the highly crystalline and hydrophobic PVDF effectively limited the swelling behavior of SPES. The vanadium ion permeability of SPES/PVDF membranes was one order of magnitude lower than that of Nafion117 membrane and pristine SPES membrane. Single cells with SPES/PVDF composite membranes showed significantly lower capacity loss, higher coulombic efficiency and higher energy efficiency than that with Nafion117 and pristine SPES membranes. The blend membrane with 40wt% of PVDF (denoted as S_0.6P_0.4) showed energy efficiency of 83.2% at 30 mA∙cm^-2, which was superior to that of the Nafion117 and SPES membranes. In the self-discharge test, S_0.6P_0.4 membrane showed twice longer duration in open circuit decay than that with Nafion117 membrane. With all the good properties and low cost, the SPES/PVDF membranes are expected to have excellent commercial prospects as ion exchange membranes for VRB system.

ZnMn₂O₄ thin films were deposited by a sol-gel technique onto a p⁺-Si substrate, and a RRAM device with the Ag/ZnMn₂O₄/p⁺-Si structure was fabricated. The microstructure of ZnMn₂O₄ films and the resistive switching behavior of Ag/ZnMn₂O₄/p⁺-Si device were investigated. ZnMn₂O₄ thin films had a spinel structure after annealing at 650 °C for 1 h. The Ag/ZnMn₂O₄/p⁺-Si device showed unipolar and/or bipolar resistive switching behavior, exhibiting different I _ON/I _OFF ratio and switching endurance properties. In bipolar resistive switching, high-resistance-state (HRS) conduction was dominated by the space-charge-limited conduction mechanism, whereas the filament conduction mechanism dictated the low resistance state (LRS). For unipolar resistive switching, HRS and LRS were controlled by the filament conduction mechanism. For bipolar resistive switching, the conduction process can be explained by the space-charge region of the p-n junction.

Banana pseudo-stem was liquefied in the mixture of polyhydric alcohols of polyethylene glycol (PEG400) and glycerol. Hydroxyl value of liquefied products ranged from 294.8 to 370.2 mg KOH/g and ${\bar M_n}$ was about 430. Liquefied products (LBPP) could be used as raw materials for polyurethane by reacting with 4, 4’-diphenylmethane diisocyanate (4, 4’-MDI) and PEG400 to synthesize liquefied product-based polyurethane (LBPP-PU) adhesive. To analyze in depth the creation of urethane linkage among LBPP, PEG400 and 4, 4’-MDI, factors which had effects on the residue content were all investigated. They were characterized by FT-IR and TG. The shear strength of LBPP-PU adhesive was improved when decreasing the percentage of the substitution of PEG400 by LBPP. The adhesive strength was obtained from T-peel of aspen/polyurethane adhesive joints, and the maximum lap shear strength (4.40 MPa) was obtained when 16.70% of LBPP was added to the LBPP & PEG400 system.

To enhance the understanding about the utilization of steel slags as a cementitious material, we comparatively studied the chemical, mineralogical and morphological properties of two types of steel slag; basic-oxygen-furnace carbon slag (BOF C) and electric-arc-furnace stainless steel slag (EAF S). Moreover, we studied the standard consistency, setting time and the effect of the slag replacement ratios on the fluidity and compressive strength of blended cement mortar. The experimental results showed that BOF C had higher alkalinity, higher pH value and more hydraulic phases than EAF S. Both types of slag showed water reduction effect due to its high fineness. Neat BOF C paste showed flash set and acceleration in the initial setting time of blended cement especially at high slag proportions. However, EAF S prolonged the setting time of blended cement even at low slag proportions. The pH values for blended cement contained 50% BOF C or EAF S were lower than those of pure cement paste. Despite of slag type, compressive strength gradually decreased with increasing slags content. The strength of BOF C mortar was higher than that of EAF S mortar with the same replacement ratio for the same age. Slag activity index demonstrated that BOF C and EAF S conformed to the Chinese National Standard (GB/T 20491-2006) requirements for steel slag as grade one and grade two, respectively.

The objective of this study was to assess the feasibility of using the plant-source polymer of the matcha powder as a composite admixture for hemihydrate gypsum. Hemihydrate gypsum was mixed with different contents of matcha powder, and then the water requirement for the normal consistency, setting times, density, strength, hydration and microstructure of the hardened mixture were evaluated. The experimental results showed that it increased the water requirement for the normal consistency, and it regulated the setting times and reduced the density. Hemihydrate gypsum with more matcha powder had the higher water requirement, longer setting times and lower density. Less than 1% matcha powder had slight impact on the strength of hardened paste, but more than 1% matcha powder had a remarkable one. Matcha powder changed the hydration process and prolonged the induction and acceleration period. Small needlelike crystals were transformed into longer, larger and thicker ones as more matcha powder was mixed. This case is closely related to the prolongation of the induction and acceleration period. Besides, more and larger pores were observed in the hardened paste with more matcha powder. It is attributed to the appearances of the tea polyphenol in matcha powder and the larger and longer crystal morphology in hardened paste as well as the high water requirement for the normal consistency. These results are important to the application of matcha powder as a composite admixture for the hemihydrate gypsum as well as the prosperity and development of the tea industry.

The physical properties and hydration of a cementitious material, which prepared mainly from the vanadium slag and phosphate slag, were investigated. These slags were investigated can be reused as original resources to prepare cement clinker based on the fact that they mainly comprise silicon and calcium phases, respectively. In this research, a batch of cement having various grades was prepared by mixing the clinker with gypsum, tailings, and fly ash. X-ray diffraction (XRD), differential thermogravimetric (DTG) as well as scanning electron microscopy (SEM) were applied to test and analyze the physical properties and hydration of the prepared cement. Experimental results suggest that the performances of the cement meet the requirements of national standards in all aspects. Its hydration process is similar to that of common Portland cement, whose hydrates were mainly composed of C-S-H, ettringite and CH. Moreover, the addition of fine particles would accelerate cement hydration, as it provided additional surfaces to help the nucleating and growing of hydrates.

A numerical model was proposed to describe the modulus variation of mortar exposed to external sulfate attack and the effectivity was verified by experiments. The model joints statistical evolution of microcracks to effective elastic modulus with microcracks and is applied to predict the damage degree of mortar attacked by sulfate. The experimental results show that the model can predict the modulus variation development of the specimen and the microcraks density. The elastic modulus values calculated by the model are consistent with that measured by experiments. The model focuses on nucleation of microcracks and finds that the theoretical results of microcracks number density show a linear growth over time in mortar. Compared with other sulfate attack damage model, this model provides a more suitable damage evolution equation that can be used to analyze the chemically assisted damage.

Crack potential and hydration processes of the cement pastes were monitored using an up-to-date eccentric steel cracking frame (ESCF), associated with the non-contact electrical resistivity apparatus, independently. The objective of employing the ESCF is to give a new method determining cracks of concrete at early age. The findings indicate that the lowest water-cement ratio paste reveals highest resistivity values, compasses an earlier inflection point and obtained higher stress. The eccentric restrained cracking test exhibited that lower water-cement ratio paste cracked at the earliest time, accordingly confirms cracking tendency is the highest. Tensile strength test and stresses utilizing ABAQUS simulation was performed. The crack initiation ages obtained are consistent with the experimental program results, which indicates that ABAQUS numerical analysis can well be utilized to predict the crack tendency of cement.

Compressive stress and tensile stress were applied to concrete specimens using test rigs designed by RILEM TC 246-TDC. Ultrasonic wave velocity and autoclam permeability system were used to characterize the damage variable and gas permeability coefficient of concrete, respectively. The experimental results show that the strain value of concrete increases with the increasing of stress level and loading time. The damage variable and gas permeability coefficient of concrete under compressive stress decrease at first and increase after a threshold value between 0 and 0.6. When the concrete is under tensile load, the damage variable and gas permeability coefficient increase with tensile stress, with a significant increase from 0.3 to 0.6 tensile stress. There is a strong linear relationship between the damage variable and the gas permeability coefficient, suggesting both as good indicators to characterize the damage of concrete under stress.

The correlation between the stress concentration and the spontaneous magnetic signals of metal magnetic memory (MMM) was investigated via tensile tests. Sheet specimens of the Q235 steel were machined into standard bars with rectangular holes to obtain various stress concentration factors. The tangential component Hp(x) of MMM signals and its related magnetic characteristic parameters throughout the loading process were presented and analyzed. It is found that the tangential component Hp(x) is sensitive to the abnormal magnetic changes caused by the local stress concentration in the defect area. The minimum magnetic field is positively correlated to the magnitude of the load and the distance from the notch. The tangential magnetic stress concentration factor presents good numerical stability during the entire loading process, and can be used to evaluate the stress concentration factor. The results obtained will be a complement to the MMM technique.

Due to the largely inhomogeneous deformation among constituent phases, the advanced high-strength multi-phase steels are always facing challenges when applied to automotive parts where local formability is critically required. In this work, two characteristic microstructures were produced from a low carbon Ti-V microalloyed steel by varying the cooling path. In the ferrite single-phase microstructure resulted from “ultra-fast cooling (UFC) + furnace-cooling (FC)”, the hole-expanding ratio of 200% and tensile strength of 647 MPa were achieved. In the ferrite-bainite-martensite (F+B+M) multi-phase microstructure produced by “UFC + air-cooling (AC) + UFC”, the ferrite has been strengthened by Ti-V carbides to promote the strain partitioning, which resulted in the tensile strength of ≥780MPa, a moderate elongation and hole-expanding ratio of 93%. The strengthening contributions of Ti-V carbides were calculated to be 126MPa and 149MPa in the ferrite single-phase and F+B+M multi-phase microstructure, respectively.

The high-temperature oxidation behavior of Fe-5wt% Cr alloys was investigated in both N₂+5vol% H₂O and N₂+21vol% O₂+5vol% H₂O atmospheres at 900–1000 °C for 120 min by the thermogravimetric analysis (TGA). The oxidation kinetics, phase composition and cross-sectional microstructure of the oxide scale were contrastively analyzed in both environments. Also, the phase composition of oxide scale was measured by X-ray diffraction (XRD). The cross-sectional microstructure and the interface elements distribution were studied by electron probe microanalysis (EPMA). The experimental results demonstrated that the growth rate and the mass gain of the oxide scale in the N₂+5vol% H₂O atmosphere were both significantly lower than the growth rate and the mass gain in the N₂+21vol% O₂+5vol% H₂O atmosphere. The apparent layer structure of the oxide scale could be observed in an oxygen-enriched environment and did not appear in a pure water vapor without oxygen. In addition, the inner oxide layer growth mechanisms and the outward diffusion of the metal cations were introduced in the atmosphere of N₂+5vol% H₂O. Consequently, the effects of temperature and humid atmosphere on the Fe-Cr spinal scale evolution were also discussed.

Plasma electrolytic oxidation (PEO) coatings were fabricated on 6063 aluminum alloy in a cheap and convenient electrolyte. The effect of different current densities, i e, 5, 10, 15, and 20 A/dm² on the microstructure and corrosion behavior of coatings was comprehensively studied by scanning electron microscopy (SEM), stereoscopic microscopy, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), respectively. It is found that the pore density decreases and the pore size increases with increasing current density. The XRD results show that the coatings are only composed of α-Al₂O₃ and γ-Al₂O₃. Potentiodynamic polarization test proves that the coating formed under 10 A/dm² possesses the best anticorrosion property. The long time EIS test shows that the coating under 10 A/dm² is able to protect the aluminum alloy substrate after long time of immersion in 0.59 M NaCl solution, which confirms the salt solution immersion test results in 2 M NaCl solution.

W-30wt%Cu and TiC-50wt%Ag were successfully synthesized by a novel simplified pretreatment followed by electroless plating. The 0wt% TiC, 0.5wt% TiC, and 0.5wt%TiC-0.5wt%Ag composite powders were added to W-30wt%Cu composite powders by blending, and then reduced. The reduced W-30Cu, W-30Cu/0.5TiC, and W-30Cu-0.5Ag/0.5TiC composite powders were then compacted and sintered at 1 300 °C in protective hydrogen for 60 min. The phase and morphology of the composite powders and materials were analyzed using X-ray diffraction and field emission scanning electron microscopy. The relative density, electrical conductivity, and hardness of the sintered samples were examined. Results showed that W-30Cu and TiC-Ag composite powders with uniform structure were obtained using simplified pretreatment followed by electroless plating. The addition of TiC particles can significantly increase the compressive strength and hardness of the W-30Cu composite material but decrease the electrical conductivity. Next, 0.5wt% Ag was added to prepare W-30Cu-0.5Ag/TiC composites with excellent electrical conductivity. The electrical conductivity of these composites (61.2%) is higher than that in the national standard (the imaginary line denotes electrical conductivity of GB IACS 42%) of 45.7%.

In order to establish the kinetics of oxidation of artificial magnetite pellets, we comprehensively studied kinetics of the oxidation of artificial magnetite pellets from low temperature to high temperature using chemical analysis. The results show that when the oxidation temperature is below 1 073 K (800 °C), the reaction is controlled by the step of internal diffusion, and the model function is 2 G(a) = 1−3(1−x)^2/3 + 2(1−x) (α, reaction degree). When the temperature is above 1 073 K (800 °C), the reaction mechanism was chemical reaction, and the model function is 1 G(a) = 1−(1−x)^1/3. The apparent activation energy for the oxidation of artificial magnetite pellets was also determined, which was 8.90 kJ/mol for the low temperature and 67.79 kJ/mol for the high temperature. Based on the derived kinetic equation for the oxidation of artificial magnetite pellets, the calculated value is consistent with the experimental data. Compared with that of nature magnetite pellets, the apparent activation energy is decreased obviously, which indicates that the artificial magnetite pellets are oxidized more easily than nature magnetite pellets.

Micro arc oxidation (MAO) coatings doped with graphene oxide (GO) were prepared on pure titanium by adding GO and sodium dodecyl benzene sulfonate (SDBS) into a sodium silicate solution. The as-deposited coatings were comparatively analyzed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The binding forces of the MAO, MAO+GO and MAO+GO+SDBS three coatings were measured by a scratch tester. The mechanical property of the three coatings was analyzed using the nano-indentation technique. The corrosion resistance of the coatings was tested by the electrochemical system in 3.5% NaCl solution. The photocatalytic activity of the prepared samples was evaluated by determining the degradation of methylene blue (MB) solution. The results showed that compared to the MAO coating, the morphologies and phase compositions of MAO+GO and MAO+GO+SDBS composite coatings were significantly different. These two composite coatings all had superior photocatalytic activity. Especially, the MAO+GO composite coating still had enhanced binding force and excellent corrosion resistance. Furthermore, the relationship between the microstructure and the properties of these three MAO coatings was analyzed.

Conductive polymers show great promise because of their electrical property based on bioelectricity in vivo. In order to search electro-activity materials which insure abduction of tissue, we synthesized conductive nerve conduits with poly-dl-lactic-acid (PDLLA) and tetra-aniline (TA). Preparation technology of TA was optimized, and the properties of the conduit were studied. RSC96 cell were used to investigate the toxicity and electrical stimulation effect. SD rats were used to assess biocompatibility in vivo. The results showed that the reaction ratio of 1:1, the reaction time of 2 h and the HCl concentration of 2 mol/L were the optimum conditions for synthesis of TA. The influence of TA content on the mechanical properties, hydrophilicity, conductivity and microstructure of the nerve conduit was evaluated. Cell and histocompatibility study showed PDLLA/TA possessed good biocompatibility. These results showed it had application values in tissue projects.

Colloidal mesoporous silica nanoparticles functionalized with carboxy-terminated polyethylene glycol (CMS-PEG-COOH) were successfully synthesized by covalently grafting dicarboxy-terminated polyethylene glycol (HOOC-PEG-COOH) on the surface of the amino functionalized CMS nanoparticles with amide bond as a cross linker. Moreover, the structural and particle properties of CMS-PEG-COOH were characterized by nuclear magnetic resonance spectroscopy (¹H-NMR), transmission electron microscopy (TEM), dynamic light scattering (DLS), nitrogen adsorption-desorption measurements, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The nanomaterials presented a relatively uniform spherical shape morphology with diameters of about 120 nm,and favorable dispersibility in weak acid solution. The CMS-PEG-COOH exhibited no changes in the state of amorphous, while the mesopores sizes of 5.25 nm might provide the nanomaterials with large capacity for the loading and releasing of drugs. So the results indicated that CMS-PEG-COOH might be a critical nanomaterial for drug delivery system in the future.

Carbon quantum dots (CQDs) exhibit tremendous advantages for plant growth study due to its strong fluorescence and good biocompatibility. The fluorescent CQDs were synthesized by the one-step microwave method with the raw materials of citric acid (CA) and urea (UR), and expressed a unique green fluorescence with the optimal excitation wavelength of over 400 nm through adjusting the doping of N elements. It is demonstrated that CQDs can act as deliver media in plant and fluorescent probes for plant cell imaging through directly cultivated in the seedlings of melon and wheat, respectively. Based on the effects of the fluorescent CQDs on plants growth, we can further study the mechanisms of the ions transport in plants.