Samples of a cobalt-based alloy that underwent a surface treatment were evaluated. The samples, which were obtained by casting alloy ASTM F 75, were ground and polished on one side until a mirror finish was obtained. The samples were encapsulated in wollastonite (W) using uniaxial pressure, treated at 1 220 °C for 1 h and subsequently tempered in water. The characterisation of the sample indicated that part of the ceramic encapsulating material was mechanically incorporated on the metallic surface by growth of the oxide layer of the alloy. After thermal treatment, a series of specimens were submerged in a solution with 5-fold simulated body fluid (5SBF) for 3, 5 and 21 days. Characterisation by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) indicated nucleation and growth of a homogenous layer of apatite, beginning on the third day when the sample was submerged.

For improving the properties of SiC-mullite composite ceramics used for solar sensible thermal storage, MnO₂ was introduced as sintering additive when preparing. The composite ceramics were synthesized by using SiC, andalusite, α-Al₂O₃ as the starting materials with non-contact graphite-buried sintering method. Phase composition and microstructure of the composites were investigated by XRD and SEM, and the effect of MnO₂ on the properties of SiC composites was studied. Results indicated that samples SM1 with 0.2 wt% MnO₂ addition achieved the optimum properties: bending strength of 70.96 MPa, heat capacity of 1.02 J·(g·K)^-1, thermal conductivity of 9.05 W·(m·K)^-1. Proper addition of MnO₂ was found to weaken the volume effect of the composites and improve the thermal shock resistance with an increased rate of 27.84% for bending strength after 30 cycles of thermal shock (air cooling from 1 100 °C to RT).

The semi-carbonization method is a kind of waste treatment to carbonize rice straw fiber at low semi-carbon temperature. The rice straw fiber is carbonized incompletely, which serves as building materials additive. The results reveal that the optimized carbonization condition is at 313 °C for 20-40 min with H₃PO₄ as activator. The structure of semi-carbonized straw fiber displays a large quantity of micropores, with which the wall thickness and the pore diameter are in the range of 1-4 μm, presenting the iodine sorption value of 1 320-1 470 mL/g and the methylene blue sorption value of 1 330-1 460 mg/g, respectively. Moreover, the acidic oxygen-containing groups impart the structure higher sorption of polar molecules. The semi-carbonized rice straw fiber with open and closed micro-mesopores demonstrates good hygroscopicity, implying the potential application as a functional additive in building materials.

Spinel LiMn₂O₄ microspheres and hollow microspheres with adjustable wall thickness have been prepared using controllable oxidation of MnCO₃ microspheres precursors and following solid reactions with lithium salts. Scanning electron microscopy (SEM) investigations demonstrate that the microsphere morphology and hollow structure of precursors are inherited. The effect of hollow structure properties of as-prepared LiMn₂O₄ on their performance as cathode materials for lithium-ion batteries has been studied. Electrochemical performance tests show that LiMn₂O₄ hollow microspheres with small wall thickness exhibit both superior rate capability and better cycle performance than LiMn₂O₄ solid microspheres and LiMn₂O₄ hollow microspheres with thick wall. The LiMn₂O₄ hollow microspheres with thin wall have discharge capacity of 132.7 mA·h·g^-1 at C/10 (14.8 mA·g^-1) in the first cycle, 94.1% capacity retention at C/10 after 40 cycles and discharge capacity of 116.5 mAh·g^-1 at a high rate of 5C. The apparent lithium-ion diffusion coefficient (D _app) of as-prepared LiMn₂O₄ determined by capacity intermittent titration technique (CITT) varies from 10^-11 to 10^-8.5 cm²·s^-1 showing a regular “W” shape curve plotted with test voltages. The Dapp of LiMn₂O₄ hollow microspheres with thin wall has the largest value among all the prepared samples. Both the superior rate capability and cycle stability of LiMn₂O₄ hollow microspheres with thin wall can be ascribed to the facile ion diffusion in the hollow structures and the robust of hollow structures during repeated cycling.

From the perspective of growth units, the growth mechanism of Mg₂(OH)₂CO₃·3H₂O whisker is investigated in this paper. Results show that the growth morphology of Mg₂(OH)₂CO₃·3H₂O whisker is consistent with the model of anion coordination polyhedron growth units. The growth solution Raman shift of Mg₂(OH)₂CO₃·3H₂O was monitored using Raman spectroscopy. The growth units are [Mg-(OH)₄]^2- and H₂CO₃. The growth process of Mg₂(OH)₂CO₃·3H₂O whisker is as follows: growth unit [Mg-(OH)₄]^2- first incorporates into the larger dimension [Mg-(OH)₄] _n ^2-, then the [Mg-(OH)₄] _n ^2- combines with H₂CO₃ into a linear skeleton Mg₂(OH)₂CO₃ in the same line. Mg₂(OH)₂CO₃ combines with H₂O by hydrogen bonds and ultimately transforms into Mg₂(OH)₂CO₃·3H₂O whisker. Magnesium carbonate whiskers have a layered structure, each of which is made of magnesium, carbon, oxygen, with H₂O in between each layer. When skeletons are superimposed within the same plane as a parallelepiped one, they grow into solid cuboid-shaped whiskers. When the parallelepiped skeletons planes combine with each other through the cascading links, they grow into hollow cylindrical whiskers.

The exfoliation degree of graphite oxide into graphene oxide plays an important role in the massive production method of reduced graphene oxide. It is significant to find a simple and feasible method to analyze the exfoliation degree of graphite oxide. In the present work, graphite oxide was synthesized by a modified Hummers method, and then graphene oxide colloids were obtained by exfoliation of graphite oxide dispersed in de-ionized water. UV-visible spectroscopy was used to characterize the absorption of the graphene oxide colloids, and the concentration of graphene oxide colloids indicated by absorption area of UV-visible spectra was studied. Results show that there is a relatively stable relationship between them, indicating that UV-visible spectroscopy is a potential method for analyzing the exfoliation degree of graphite oxide into graphene oxide.

Simultaneous thermal analysis was used to study the influence of Vitamin C as possible chemical additive inhibiting coal oxidation process at low temperature. Some oxidation characteristics of Vitamin C affecting the coal oxidation were investigated at different heating rates. The TG-DSC data show that the impact of Vitamin C on coal oxidation process can be directly evaluated using ignition temperature and critical temperature. Comparison with the effect of water on coal oxidation shows that Vitamin C is more efficient than water. However, the blank experiment conducted with inert α-Al₂O₃ also suggests that Vitamin C can decompose at about 200 °C, which limits the usage of Vitamin C on inhibiting coal oxidation.

In order to study the squeeze-strengthening effect of silicone oil-based magnetorheological fluid (MRF), theoretical basis of disc squeezing brake was presented and a squeezing braking characteristics test-bed for MRF was designed. Moreover, relevant experiments were carried out and the relationship between squeezing pressure and braking torque was proposed. Experiments results showed that the yield stress of MRF improved linearly with the increasing of external squeezing pressure and the braking torque increased three times when external squeezing pressure achieved 2 MPa.

Porous SiO₂-Si₃N₄ composite ceramics with high porosity and excellent mechanical properties were fabricated by pressureless-sintering at relatively low temperature of 1 500 °C using diatomite as pore forming agent. The effects of diatomite on flexural strength, fracture toughness, shrinkage, porosity and phase transformation of the porous ceramics were investigated in detail. Compared with that of the ceramic without adding diatomite, the porosity of the ceramic with 10% diatomite is increased by about 27.4%, the flexural strength and fracture toughness reaches 78.04 MPa and 1.25 MPa·m^1/2, respectively. As the porosity increases, the dielectric constant of porous SiO₂-Si₃N₄ ceramic decreases obviously from 3.65 to 2.95.

The application of rolling for fabricating grate on titanium stripe has been explored in this paper. Then the mechanically robust Ti(C,N) diffusion layer was synthetized directly on the grates by laser carbonitriding in the mixture gas of nitrogen and methane. The results shows that the carbonitriding process is accelerated by temperature enhancement with decreasing scanning speed. The Ti(C,N) diffusion layer is kept at 2 μm in thickness, when the scanning speed is smaller than 4 mm/s. The contact angle increases from 20° to 143.6° by designing an appropriate grate size and surface roughness. Meanwhile, the relationship between hydrophobicity, hardness performance and scanning speed is also discussed. The hardness of diffusion layer increases with decreasing laser scanning speed, and is up to 11.2 GPa. The surface structure and hydrophobic state are maintained after three cycles of sandpaper abrasion, which has improved the robustness of surface grate.

The mechanism of the surface depression of the foam glass was studied. A method of powder sintering with plate glass as the raw material and carbon black as the foaming agent was adopted to investigate the influences of foaming temperature, soaking time, moisture content in the release agent, and flame preheating temperature on the surface depression of a foam glass blank. The results indicated that insufficient cooling rate and rapid foaming process that could not react synergistically with the surface tension and viscosity of the glass melt aroused the mismatching between the glass melt and the expansion or contraction of gas, resulting in upper surface depression of foam glass. Besides, the batch carbon black at high temperature reacted with residual water in advance to generate large amounts of gas and form the air space which could expand inside, leading to lower surface depression of foam glass.

A density functional plane-wave pseudopotential method is used to study the doping mechanisms of impurity defects(Bi_Ba, Y_Ti) in BaTiO₃-BiYO₃. Single Bi_Ba and Y_Ti impurities have little structure distortion. Bi forms ionic bond with nearby O atom in single Bi impurity, Y formed [YO₆] octahedral in single Y impurity. However, in the co-doped Bi_Ba and Y_Ti structure, Bi formed three valence bonds with nearby O atom, which causes the large structure distortion. The doped ion makes the mobile of Ti⁴⁺ difficult and loss local ferroelectricity, which will broaden the dielectric constant temperature curve and increase the temperature stability of BaTiO₃ ceramic matrix.

The Y₃Al₅O₁₂ (YAG) nanocrystals were synthesized by ultrasound-assisted and ultrasound-microwave-assisted alkoxide hydrolysis precipitation methods. The structures and morphology of the YAG were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The synthesis kinetics of two kinds of YAG nanocrystals was investigated using differential thermal analysis and thermo gravimetric analysis (DTA-TG) at different heating rates in argon gas. The results show that two kinds of YAG precursors have one obvious endothermic peak at 315-600 K. The apparent activation energy of two kinds of YAG precursors was calculated using the Doyle-Ozawa and Kissinger methods, the coefficients of reaction order, frequency factor and kinetic equations were also determined. The average apparent activation energy for the YAG precursor prepared by ultrasound-microwave assisted was calculated to be 80.76 kJ·mol^-1 higher than the YAG precursor prepared by ultrasound-assisted synthesis (56.56 kJ·mol^-1).

The crystal intrinsic orientation effect on the piezoelectric response of multi-domain 0.26Pb(In_1/2Nb_1/2)O₃–0.46Pb(Mg_1/3Nb_2/3)O₃–0.28PbTiO₃ (PIN-PMN-0.28PT) crystals was investigated by coordinate transformation method. The results indicate that crystal intrinsic orientation effect plays a crucial role in determining the piezoelectric properties of multi-domain crystals. Almost 58% and 69% of the transverse piezoelectric coefficients d ₃₁ and d ₃₂, respectively, and 67% longitudinal piezoelectric coefficient d ₃₃ of multi-domain PIN-PMN-0.28PT crystals poled along [011] _c originate from crystal intrinsic orientation effect. For [001] _c poled multi-domain PIN-PMN-0.28PT crystals, intrinsic orientation effect contributes to the transverse and longitudinal piezoelectric coefficient at least 79% and 74%, respectively.

The complete deposition distribution process of calcium carbonate is summarized in three directions of cracks. Distribution of calcium carbonate in the self-healing process of microbial concrete is studied in detail, with the help of a variety of analytical techniques. The results show that carbonate deposits along the x-axis direction of the cracks. The farther from the crack surfaces of concrete matrix in x-axis direction, the more the content of the substrate, the less content of calcium carbonate. Gradual accumulation of calcium carbonate along the y-axis direction is like building a house with bricks. Different repair points are gradually connected, and ultimately the whole of cracks are completely filled. In the z-axis direction, calcium deposits on the surface of fracture direction, when the crack is filled on the surface, because the internal crack hypoxia in the depths of cracks hardly produces calcium carbonate.

Requirements of self-compacting concrete (SCC) applied in pre-stressed mass concrete structures include high fluidity, high elastic modulus, low adiabatic temperature rise and low drying shrinkage, which cannot be satisfied by ordinary SCC. In this study, in order to solve the problem, a few principles of SCC design were proposed and the effects of binder amount, fly ash (FA) substitution, aggregate content and gradation on the workability, temperature rise, drying shrinkage and elastic modulus of SCC were investigated. The results and analysis indicate that the primary factor influencing the fluidity was paste content, and the main methods improving the elastic modulusof SCC were a lower sand ratio and an optimized coarse aggregate gradation. Lower adiabatic temperature rise and drying shrinkage were beneficial for decreasing the cement content. Further, based on the optimization of mixture, a C50 grade SCC (with binder amount of only 480 kg/ m3, fly ash substitution of 40%, sand ratio of 51% and proper coarse aggregate gradation (V _{5-10 mm}: V _{10-16 mm}: V _{16-20 mm}= 30%: 30%:40%)) with superior workability was successfully prepared. The temperature rise and drying shrinkage of the prepared SCC were significantly reduced, and the elastic modulus reached 37.6 GPa at 28 d.

To better understand and assess the effect of microfines on concrete properties, the synergetic effect of methylene blue value and content of microfines on properties of low and high strength concrete was studied and then the relationships between the index of modified methylene blue value (MMBV) and concrete properties were investigated. The results show that relationships between MMBV and fresh and hardened properties of concrete can be fully established, and the correlation between MMBV and C60 concrete property is higher than the correlation between MMBV and C30 concrete. With the increase of MMBV, concrete workability and frost resistance decrease while drying shrinkage decreases; however, compressive strength and chloride-ion penetration resistance of C30 concrete have not been negatively affected whereas those of C60 concrete are significantly deteriorated when MMBV exceeds 100. To make use of microfines without remarkably damaging concrete quality, it is suggested that MMBV of microfines in MS used in C30 and C60 concrete be no more than 100.

Nano particles have been found to be effective in enhancing many properties of regular concretes. However, there is little information on the effect of nano particles on shotcrete. In fact, if similar positive effect of nano particles can also appear in shotcrete, they will greatly benefit the wide application of shotcrete in more and more repair and strengthening of structures in civil engineering, especially in corrosive environments. In this study, through experiments on 70 specimens, the effects of nano SiO₂, CaCO₃ and Al₂O₃ particles on the early-age porosity, pore size distribution, compressive strength and chloride permeability of shotcrete were investigated.Test results indicated that nano SiO₂ particles significantly increased the compressive strength and chloride penetration resistance; nano Al₂O₃ and CaCO₃ particles had slight enhancing effect on the compressive strength; nano CaCO₃ particles were most effective in promoting the chloride penetration resistance of shotcrete. As a conclusion, nano SiO₂ particles were recommended when both early age compressive strength and chloride penetration resistance were crucial, and nano CaCO₃ particles were recommended when only chloride penetration resistance was concerned for their high cost-effectiveness.

In order to improve the prediction accuracy of compressive strength of concrete,103 groups of concrete data were collected as the samples.We selected seven kinds of ingredients from the concrete samples, using Grid-SVM, PSO-SVM, and GA-SVM models to establish the prediction model of cubic meter compressive strength of concrete.The experimental results show that SVM model based on Grid optimization algorithm,SVM model based on Particle swarm optimization algorithm,SVM model based on Genetic optimization algorithm mean square error respectively are 0.001, 0.489 8, and 0.304 2, correlation coefficients are 0.994 8, 0.994 6, and 0.993 0. It is shown that cubic meter compressive strength prediction method based on Grid-SVM model is the best optimization algorithm.

A trial test method is introduced to form and magnify regular interface. Through researching on the carbonation of the magnifying interfacial transition zone (ITZ), the practical carbonation of the concrete can be simulated. Because the diffusion rate of CO₂ in the ITZ is several times greater than that in the bulk paste, the diffusion rate and direction of CO₂ will change and form a new carbonation front line. An interfacial effect zone caused by the ITZ will change the distribution of the complete carbonation zone and the partial carbonation zone. One of the important reasons for the formation of the partial carbonation zone was the existence of the interfacial effect zone. Consequently, the method mentioned in this paper provides a new way for researching on the microstructure of the cement based materials during the carbonation process.

Anodic oxide films grown on titanium alloy Ti-10V-2Fe-3Al in the solution of sodium tartrate, then sealed in boiling deionised water and calcium acetate solution were observed by using field emission scanning electron microscopy (FE-SEM), and were chemically analysed by using energy dispersive spectroscopy (EDS). Corrosion behaviour was investigated in a 3.5% sodium chloride solution, using electrochemical impedance spectroscopy (EIS). The morphology of the anodic oxide films was dependent on the sealing processes. The surface sealed in calcium acetate solution presented a more homogeneous and smooth structure compared with that sealed in boiling deionised water. The corrosion resistance of the oxide films sealed in calcium acetate solution was better than that sealed in boiling deionised water.

X65, X70, and X80 belong to high grade pipeline steels. Toughness is one of the most important properties of pipeline steels when the pipeline transports the gas or oil, and the means to control toughness is very important for exploring even higher grade pipeline steels. We established the relationship between toughness and crystallographic parameters of high grade pipeline steels by studying the crystallographic parameters of X65, X70, and X80 using EBSD and analyzing Charpy CVN of X65, X70 and X80. The results show that the effective grain size, the frequency distribution of grain boundary misorientation and the ratio of high angle grain boundary to small angle grain boundary are important parameters. The finer the effective grain size, and the higher the frequency distribution of grain boundaries (≥ 50°), the more excellent toughness of high grade pipeline steels will be.

In order to study the mechanism of grain refinement induced by laser shock processing (LSP) in AZ31 magnesium alloy, the specimens were processed with Nd:glass pulse laser shocking and the microstructures of LSP specimens near the surface were examined by optical microscopy and transmission electron microscopy. Optical microstructure pictures show that the size of grains formed in the top surface layer is about 4-6 μm, which is obviously different from the original grains (with an average size of 20-30 μm) in the substrate in AZ31 magnesium alloy. Transmission electron microscopic observations show that the grain refinement process of AZ31 alloy by laser shock processing includes three stages. At the early stage of LSP, the lower strain and strain rate activates the three dislocation slip systems which include basal plane system, prismatic plane system and pyramidal plane system, with the deformation governed mainly by dislocation. At the intermediary stage, dislocation slip is hindered at grain boundaries and becomes more difficult to continue during LSP. Then, parallel twins appear, which divide the original coarse grains into finer twin platelets. Finally, high-density dislocation walls are formed and subdivide twins into sub-grains. Dynamic recrystallization occurs in the process of further deformation and forms recrystallized grains when strain energy reaches the value needed by recrystallization, which leads to refinement of the grains in the top surface layer.

Deformation modes have strong effects on deformation textures and subsequent annealing textures during hot working of metals. Micro-textures and macro-textures during hot axisymmetric and planar compressive deformation and subsequent annealing processes of Al-Zn-Mg-Cu-Zr alloy were investigated by EBSD and XRD respectively. The EBSD testing indicated that for the axisymmetric compressive deformation, Brass along the α-fiber and Goss present in the sample deformed at 350 °C, Rotated-Cube was present and Brass transformed to Goss along α-fiber after annealing; Rotated-Cube appeared only in the deformation at 420 °C, which decreased and Brass appeared after annealing. For the planar compressive deformation, Rotated-Cube and Brass aligned to α and β fibers present in the deformation at 350 °C, Rotated-Cube texture transformed to Brass along the α-fiber after annealing; Rotated-Cube and Brass were present in the deformation at 420 °C, and the Rotated-Cube was enhanced and Brass transformed to Goss after annealing. Shearing textures dominated on the surface of the specimen. XRD testing showed that Rotated-Cube and a few Goss dominated in the thick-plates formed by upsetting and drawing, which transformed to Cube after annealing; However, Brass and Cube textures present in the thick-plates formed by rolling besides Rotated-Cube and Goss textures, which remained in the plates after annealing.

The purpose of this study is to investigate the influence of samarium addition on the microstructures and mechanical properties of Al-5Cu alloys. The microstructures were examined by optical microscopy, X-ray diffraction, scanning electron microscopy, energy diffraction spectroscopy and differential thermal analysis. It was found that Sm was capable significantly of affecting the microstructures of Al-5Cu alloys. When 0.4 wt% Sm was added into the alloy, the aspect ratio and the mean area of Al₂Cu phase were 10.9 and 61.0 μm². They were decreased by 31.5% and 43.3% when compared with unmodified alloy. Meanwhile, a kind of nano size strengthening Al₂Sm phase was formed in Al-5Cu alloys. In addition, the differential thermal analysis results showed that Sm addition results in a decrease in the melting temperature of α-Al and Al₂Cu. And a good combination of yield strength (244.5 MPa), ultimate tensile strength (269.4 MPa) and elongation (6.9%) was obtained when the Sm addition was 0.4 wt%. Compared with unmodified Al-5Cu alloys, they were increased by 37.6%, 35.2% and 21.1%, respectively.

By using the finite element method (FEM), we comprehensively analyzed the fields of temperature, organization, and stress in 35CrMo train axles during the quenching process is conducted, and experimentally studied the formation and evolution of inner stresses in axles during the quenching process. The results show that in the quenching process, stresses on the axle surface change from tensile to compressive gradually, while stresses in the axle core change from compressive to tensile gradually. Heat stresses and the amount of martensitic transformation are all increased with the increase of cooling rate. As a result, the maximum instantaneous stresses in the axle are increased greatly when the cooling rate is increased with brine quenching. Large instantaneous tensile stress in the axle core with brine quenching is very likely to cause quench cracking and should be avoided.

The impact toughness scattering in the ductile-brittle transition temperature (DBTT) region was experimentally examined on mixed and homogeneous grains of low alloy high strength bainitic steel under dynamic loading conditions. The results revealed that the mixed grain microstructure had larger impact toughness scattering than the homogeneous one, and the impact toughness scattering was mainly caused by the scattering in the cleavage fracture stress σ _f. The value of σ _f is related to the size of the microcrack formed in the bainitic packet. When a bainitic packet-sized microcrack propagates from one bainitic packet into the adjacent packet, cleavage fracture occurs. The cleavage fracture is controlled by the few coarse packets in the microstructures, and the σ _f scattering is influenced by the varied distances/relative locations between these coarse packets, and homogenizing the distribution of fine bainitic packet sizes is an effective way to reduce the impact toughness scattering in the DBTT region.

The recrystallization behavior of a Nb-bearing steel was investigated during multipass deformation under continuous cooling conditions. By a series of six-pass compression tests conducted on a thermomechanical simulator, the effect of deformation parameters, including strain, strain rate and interpass time, on the no-recrystallization temperature (T _nr) was determined. The results show that T _nr decreases with increasing strain and also decreases slightly with increasing strain rate. The strain has more appreciable influence on the T _nr compared with strain rate. When the interpass time is less than 10 s, the T _nr decreases with increasing interpass time. The mathematical model of T _nr was established considering the effect of pass strain, strain rate and interpass time. The calculated results agreed well with the actual experimental value.

We comparatively studied the mechanical properties anisotropy, microstructure and texture of the commercial and the new developed AA6111 alloys through tensile test, optical microscopy, and XRD analysis. The results show that the anisotropy of mechanical properties for the developed AA6111 alloy is lower than that of the commercial alloy. The developed alloy possesses higher r value, lower Δr value and more uniform microstructure, compared with the commercial AA6111 alloy, indicating that the deep drawability of the developed alloy has been improved significantly. The recrystallization textures of the two alloy sheets are also different. The recrystallization texture of the commercial alloy sheet mainly includes Cube and {114}<311> orientations, while the recrystallization texture of developed alloy sheet consists of Cube, Goss and R orientations. The relationships among the deep drawabilities, microstructure and texture were discussed thereafter.

The carbon dioxide corrosion behavior of low alloy pipeline steel was investigated by immersion experiment. Optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) were used to reflect the microstructure of the tested material and the corrosion morphology characterization. Results show that precipitate particles may accelerate the iron cabonate crystal formation process of the nucleation growth and promote the formation of compact layer. The major corrosion phases are FeCO₃ and complexity compound containing Fe and Cr. The corrosion behavior consists of three stages. At the first stage, a thin inner layer and an inhomogeneous outer layer have appeared. At the second stage, the outer layer becomes homogeneous and compact, which prevents corroding the steel substrate further. At the third stage, iron carbonate crystal tends to nucleate and grow locally. The corrosion rate obtained by weight loss method increases abruptly first and then decreases quickly with increasing corrosion time. The mutual relation among microstructure, corrosion surface morphology, corrosion phases and corrosion kinetics is discussed.

Poly (3, 4-ethylenedioxythiophene) (PEDOT), together with its dopes, such as poly (styrene sulfonate) (PSS), has been acknowledged to have a wide range of biomedical applications as an important conducting polymer. In this study, gelatin can be polymerized into PEDOT/PSS polymers on indium tin oxide (ITO)-coated glass. PEDOT/PSS/gelatin layer on ITO-coated glass significantly decreases electrochemical impedance spectroscopy (EIS) and increases charge delivery capacity relative to the gelatin layer and bare ITO-coated glass, comparable to the PEDOT/PSS layer on ITO-coated glass. PEDOT/PSS/gelatin layer on ITO-coated glass enhances pheochromocytoma (PC 12) cell affinity, possesses a high biocompatibility and promotes PC 12 cell growth by delivery of electrical stimulation. These results suggest that gelatin can be incorporated into the PEDOT/PSS polymers through electrochemical polymerization and the PEDOT/PSS/gelatin layer on ITO-coated glass possesses high electrochemical and biological activities.

A new magnesium phosphate bone cement (MPBC) was prepared as a byproduct of boroncontaining magnesium oxide (B-MgO) after extracting Li₂CO₃ from salt lakes. We analyzed the elementary composition of the B-MgO raw materials and the effects of calcination temperature on the performance of MPBC. The phase composition and microstructure of the B-MgO raw materials and the hydration products (KMgPO₄·6H₂O) of MPBC were analyzed by X-ray diffraction and scanning electron microscopy. The results showed that ionic impurities and the levels of toxic elements were sufficiently low in B-MgO raw materials to meet the medical requirements for MgO (Chinese Pharmacopeia, 2010 Edition) and for hydroxyapatite surgical implants (GB23101.1-2008). The temperature of B-MgO calcination had a marked influence on the hydration and hardening of MPBC pastes. Increasing calcination temperature prolonged the time required for the MPBC slurry to set, significantly decreased the hydration temperature, and prolonged the time required to reach the highest hydration temperature. However, the compressive strength of hardened MPBC did not increase with higher calcination temperatures. In the 900-1 000 °C temperature range, the hardened MPBC had a higher compressive strength. Imaging analysis suggested that the setting time and the highest hydration temperature of MPBC pastes were dependent on the size and crystal morphology of the B-MgO materials. The production and microstructure compactness of KMgPO₄·6H₂O, the main hydration product, determined the compressive strength.

The aim of this study was to investigate the effects of two bleaching systems on micro hardness, surface roughness and color stability of two novel dental composites. Ormocer based restorative Admira and nano-filled composite Clearfil Majesty Esthetic were bleached with 10% carbamide peroxide (Opalescence PF) or 35% hydrogen peroxide (Beyond Max 5) and subsequently immersed in four different staining solutions (coffee, tea, red wine, and cola). Distilled water was used as a control. Color measurements were performed with a spectrophotometer. Vickers micro hardness and roughness data were analyzed with two-way analysis of variance for repeated measures. The analysis of variance was used to compare the color change values. Duncan’s multiple comparison test was applied to compare the results (α = 5%). ΔE _ab ^* values over 3.3 were considered clinically unacceptable. Micro hardness and surface roughness values of the tested composites were decreased significantly after bleaching applications. Red wine and tea storage caused perceptible discolorations in the composite resin materials after 30 days of 3-hour immersion. Home or office bleaching applications can affect the surface properties of resin composites and accelerate the staining process.

Norfloxacin complexes Co(nor)₂·8H₂O (nor=norfloxacin) and [Co(nor)(phen)]NO₃·2H₂O (phen=1,10-phenanthroline) were synthesized and their biological activity on Tetrahymena and Escherichia coli (E.coli) was assayed by means of microcalorimetry. Massive experimental parameters such as the growth constant k, inhibitory ratio I, half inhibition concentration IC ₅₀ and generation time T _G were obtained. Data showed that with the increase of exposing complex concentration, both complexes exhibited strong inhibition during the growth of organisms. While toxic degrees were quite different on Tetrahymena and E. coli, due to various toxic mechanisms. And complex molecular volume and the ability of the complex penetrating into cells may be the keys.

Blended fly ash/blast-furnace slag geopolymers are focused on due to their excellent mechanical and chemical resistant properties. We investigated the effect of slag partial substitution for fly ash on the efflorescence of the resulting geopolymers. The efflorescence of geopolymer binders was inspected and evaluated through leaching tests. The efflorescence deposits on surface of the geopolymer binders were analyzed using XRD and SEM-EDS. The results showed that sodium and calcium cations leached from geopolymer binders reacted with the atmospheric CO₂ and formed the crystal deposits, gaylussite and calcite, in the forms of granular and angular crystal particles. The slag addition led to a refinement of the pore structure of fly ash-based geopolymers, but an increment in the concentration of alkali leaching. The crystal deposits gradually developed in the pore volume of the binders, and finally exceeded the capacity of pore volume. The extent of efflorescence on the surface of specimens increased with the slag substitution. The visible efflorescence is therefore a result of available alkalis and pore sizes and volumes. Higher concentration of available alkalis and smaller pores (and volume) will lead to more intensive efflorescence.

To develop a novel method predicting the viscoelastic behavior of polymer matrix composites according to the viscoelasticity of the matrix, we used the viscoelastic model of the matrix to build new models for unidirectional composites in both 0° and 90° directions. Viscoelastic parameters for both new models were derived, and the obtained equations shared the same form as the viscoelastic constitutive equation of matrix material. The viscoelastic behaviors of matrix material and unidirectional composites were also tested. Results showed that fitting parameters of creep compliance equation were close to the theoretical values of viscoelastic constitutive parameters of the unidirectional composites, proving the validity of the models. A new method was obtained to predict the viscoelastic property of the unidirectional composites based on the viscoelastic property of composite matrix and elastic property of the unidirectional composites. This method provides a theoretical basis for future studies on the viscoelasticity of composite laminates.

Poly(Imino Ketone) (PIK) is a group of novel high performance polymer material with excellent thermal properties and dissolubility. Aiming at the requirements of inertial confined fusion (ICF) studies on low density polymer foams, we firstly synthesized poly(imino imino ketone) (PIIK) by palladium catalyzed C-N cross-coupling reaction, and successfully prepared the PIIK foam material with a density of 80-300 mg/cm³ by using PIIK as the raw material with thermal-induced phase separation and lyophilization technique. Mercury injection method was used to determine the structure of PIIK foams, and the results indicated that the mean pore diameter was lower than 5 μm and it had relatively high voidage and specific surface area.

Composite made of short-cut carbon fiber mat and vinyl ester resin was observed to be an effective sensor for tensile strain up to 6 000 με. Based on its strain sensitivity, a skin-like sensitive layer which can continuously cover the structural surface to sense strain in large area was developed. The sensitive layer was applied to continuously monitor the deformation of a simply supported beam. The result indicates that the fractional change in electrical resistance of the sensitive layer reversibly reflects the beam deformation in each section and describes the distribution of the average strain of the beam. The effect of temperature change on the monitoring was studied by monitoring tests conducted at different temperatures ranging from 20 to 80 °C, which reveals temperature sensitivity in the sensitive layer and the temperature dependence of the piezoresistive behavior when the temperature exceeds 50 °C. By the application of differential connection principle, a method for temperature compensation was established and the gauge factor for the monitoring was dramatically increased. This method was verified experimentally.

In order to make clear the interaction mechanism of single component epoxy in cementitious environment, the interaction between epoxy resin and active silanol, epoxy resin and alkali was investigated From solid-state ¹³C NMR and FT-IR tests, it is confirmed that silanol group can initiate epoxy resin. Test results have also revealed that alkali as the dominant product of cement hydration can open the epoxide ring making epoxy harden.