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In recent years, nanofluids as heat transfer fluids have shown huge potential in heat exchange systems. However it is still needed to discover new types of nanofluids with excellent thermal conductivity, dispersion stability and low viscosity to expand its applications. In the present work metal nanoparticles (copper or silver)-filled carbon nanotubes (Cu@CNT, Ag@CNT) have been synthesized by a simple ultrasonic-assisted impregnation combined with chemical reduction. The morphology, phase structure, and degree of crystallization of the prepared nanocomposites have been characterized in detail. Two kinds of nanofluids, including water-based and ethylene glycol-based, have been prepared employing the nanocomposites without adding any surfactant. The dispersion stability, thermal conductivity, and viscosity of the hybrid nanofluids with different mass fraction are studied systematically. The results show that the hybrid nanofluids process good dispersion stability and high thermal conductivity. No obvious delamination can be observed in all nanofluids (0.01–0.05 wt%) after standing for 6 months. The maximum enhancement in thermal conductivity for water-based and ethylene glycol-based Ag@CNT nanofluids with mass fraction of 0.05 wt% reach 52.37% and 40.42% respectively at 65 °C, compared to the base fluid. And the Cu@CNT and Ag@CNT hybrid nanofluids exhibit higher thermal conductivity and lower viscosity than functionalized CNT nanofluids. These results indicate that the metal nanoparticles-filled CNTs composites can be used to improve the thermal conductivity of nanofluids and promote the development of new thermal conductive agents.

In micromechanical simulations of asphalt mixtures, complex shapes of asphalt mortar and coarse aggregates require numerous elements in the finite element (FE) representation. This makes s...

Recently, capacitive deionization (CDI) has attracted considerable interest as a potential desalination technique for seawater. It is thus desirable to develop low-cost, sustainable, and efficient electrode materials for desalination. In this study, the polyporphyrin was prepared by a one-pot reaction from biobased furan derivative, followed by activation to manufacture nitrogen-doped polyporphyrin derived porous carbons (NPPCs) for efficient capacitive deionization. In the presence of KOH as a pore activator, NPPCs exhibited cross-linked interconnected nanosphere chain-like structures inherited from the polyporphyrin backbone with coexisting mesopores and micropores, leading to extremely high specific surface area (2979.3 m2 g−1) and large pore volume (2.22 cm3 g−1). The electrochemical measurements revealed good conductivity, outstanding stability, and extraordinary specific capacitance (328.7 F g−1) of NPPCs, which can be ascribed to rich nitrogen content (8.0 at%) and high Pyrrolic nitrogen ratio. Due to their superior hierarchical porous structure and excellent electrochemical performance, the NPPC-800 electrodes presented a high salt adsorption capacity (SAC) of 35.7 mg g−1 and outstanding cycling stability in 10 mM NaCl solution at 1.2 V during the desalination tests. This work demonstrates the utilization of biobased porous carbon material will pave a prospective way in sustainable and potential applications for CDI technique.

Cellulose nanocrystals (CNCs), which are derived from the most abundant and inexhaustible natural polymer, cellulose, have received significant interest owing to their mechanical, optical, chemical, and rheological properties. In order to transport CNC products conveniently and efficiently, they are ideally dried and stored as powders using freeze-drying or spray-drying technologies. The redispersibility of CNC powders is quite important for their end use; hence, a convenient method is required to characterize the redispersibility of CNC powders. In this paper, the possibility of characterizing the redispersibility of CNC powders by particle size analysis using dynamic light scattering (DLS) was investigated by comparing the results from transmission electron microscopy (TEM) and DLS. The particle size obtained with DLS approximately matched that obtained with TEM. Compared with TEM, DLS is a quick and convenient method to measure the particle size distribution of CNCs in water. Two kinds of dispersing methods, sonication and high-speed shearing, and two kinds of CNCs prepared by different methods, sulfuric acid hydrolysis and the TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) oxidization method, were used to study the redispersibility of CNCs. Sonication was more efficient than the high-speed shearing method for nanoscale dispersion of CNC powders in water. CNCs prepared by sulfuric acid hydrolysis could be more easily redispersed in water than those prepared by TEMPO oxidation.

In order to increase the curing rate of polymeric diphenylmethane diisocyanate (PMDI) resin, different contents of lignin-containing cellulose nanofibrils (L-CNFs) were blended into the PMDI. Differential scanning calorimetry (DSC) was used to examine how the addition of L-CNFs influences the curing kinetics of PMDI resin. The activation energy (Ea ) of the curing reaction of PMDI/L-CNF systems was calculated using the Kissinger, Friedman and Flynn-Wall-Ozawa model-free methods. The results showed that Ea values calculated by the aforementioned three methods varied in a similar trend with the increase in the L-CNF content. Adding L-CNFs could decrease the Ea value of the curing reaction of PMDI and speed up the curing reaction. The acceleration of the cure rate of the PMDI resin upon the addition of L-CNFs may be attributable to the effective dispersion of the L-CNFs into the PMDI resin as well as the reaction between the hydroxyl (-OH) groups of the L-CNFs and the isocyanate (-NCO) groups of the PMDI.

Aggregates in contact constitute the skeleton of the asphalt mixture and affect load transmission in the mixture, which determines its deformation resistance. The objective of this study is...

This study focuses on stress–displacement curves and shear fracture energy of asphalt-aggregate systems subjected to direct shear loading for four different experimental conditions. The methodology...

In this study, we used a microwave reaction to fabricate necklace-like ZnS with a hierarchical structure dispersed on the surface of graphene sheets (ZnS NHS-G). The structure and properties of the ZnS NHS-G were characterized based on X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, photoluminescence spectroscopy, electrochemical impedance spectroscopy, and the photocurrent response. The results showed that a clear increase in the photocatalytic performance was achieved with ZnS NHS-G, which was attributed to the longer lifetime of the photogenerated electrons. Furthermore, the unique morphology of the necklace-like hierarchical structure enhanced its photocatalytic properties. Thus, this semiconductor may be used as an efficient photocatalyst in the future.

Thermal barrier coatings with multi-sized porous structure at micro and nano scales were prepared with hollow spherical YSZ powders and polypropylene powders through atmospheric plasma spraying. The thermal conductivities of the multi-sized thermal barrier coatings after a long-term serving at high temperature were tested through laser flash heating method. Meanwhile, the physical models of thermal barrier coatings with multi-sized porous structure at micro and nano scales were constructed through Ansys Workbench. The evolutions of thermal conductivity of thermal barrier coatings with multi-sized pores after long-term service at 1100 °C were investigated through computation. It was found that the thermal conductivity of the coating increased with the extension of the serving time. When the serving time reached 60 days, the thermal conductivity of the coating tended to be stable and close to the compacted bulk. The computational results were consistent with the tested ones, which could be helpful to explain the thermal conducting evolution in thermal barrier coatings with multi-sized porous structure at nano and micro scales after long-term serving at high temperature.

Currently, recovering the natural hydrological cycle and lowering urban flood risk are global challenges. A permeable pavement with void-rich pavement materials, such as porous asphalt (PA)...

A series of novel cyclic carbonate-functionalized polysiloxanes (CC) were successfully prepared by the reaction of epoxy-functionalized polysiloxanes with carbon dioxide. Then the CCs with different carbonate content were reacted with various structural diamines such as isophorondiamine (IPDA), 4,4′-diaminodicyclohexylmethane (PACM), 1,2-proplenediamine (PDA) and 1,6-hexamethylenediamine (HMDA) to form non-isocyanate polyurethane (NIPU) coatings, respectively. The properties of the NIPU coatings were determined, and the effects of carbonate content as well as chemical structure of diamine on mechanical and thermal properties of NIPU coatings were investigated. The results showed that the cycloaliphatic amines cured coatings had higher tensile strength, Yong’s modulus, water resistance and glass transition temperature compared to the aliphatic amines cured coatings. Furthermore, with the increase of the carbonate content, the tensile strength, Yong’s modulus and glass transition temperature of the coatings were increased, while the thermal stability and water resistance of the coatings were decreased.

The equivalent plasticity strain (EPS) of snow-melting heated pavement concrete that exposed to inner elevated temperatures is analyzed with finite element simulations. An optimal mix proportion of the concrete with high thermal conductivity was obtained through mechanical and thermal experiments, which helps facilitate reducing the damage in snow-melting pavement. A three-dimensional (3D) finite element model is developed based on the concrete damage plastic (CDP) model with parameters. The EPS is considered as the performance evaluation index for damage in snow-melting heated pavement concrete. Based on the results of finite element simulations, the EPS of snow-melting heated pavement concrete that exposed to inner elevated temperatures was analyzed under different pavement structures and external conditions. Furthermore, two EPS prediction models were proposed: the one is for EPS and the inner elevated temperature, the other is for EPS and five key factors. The outputs of 3D finite element simulations were verified by an experiment result. It indicated that numerical results agreed with experimental results very well. A prediction and evaluation method of damage for snow-melting heated pavement concrete was established as well.

Thermosetting polymers possess high dimensional stability, chemical resistance and thermal stability, and they are indispensable for many applications. However, conventional thermosetting polymers cannot be reprocessed and reshaped due to their permanent cross-linked structure. Therefore, recycling of thermosetting polymers is a serious challenge. Degrading thermosetting polymers into soluble oligomers and reuse of the oligomers in new resin systems may provide a favorable way to solve this problem. In this work, we developed an efficient method for chemical degradation of anhydride-cured epoxy using environmentally benign phosphotungstic acid (HPW) aqueous solution as the catalyst system at a mild reaction temperature of 190 °C. During reaction, the ester bond in the cross-linked structure was selectively cleaved, and the thermosetting polymer was fully converted to oligomers that contain multifunctional reactive groups. When the decomposed matrix polymer (DMP) was used as a reactive ingredient and added up to 40 wt% in the preparation of a new anhydride-cured epoxy curing system, the resulting cross-linked polymers still retained the mechanical properties of the neat polymer.

Sphericity, form dimensions, and angularity are important morphological properties of aggregates that significantly affect the microstructure of grain-based materials and their macromechani...

In the present study, a novel silver nanoparticles-decorated three-dimensional graphene-like porous carbon (Ag/3D GPC) nanocomposite has been synthesized via the method of carbonization and reduction of silver ions at the same time. This Ag/3D GPC nanocomposite possess an interconnected network of well crystalized and submicron-sized macropores with thin graphene walls of several nanometers, where silver nanoparticles distributing uniformly. The water based and ethylene glycol based Ag/3D GPC hybrid nanofluids have been prepared without any surfactant. The hybrid nanofluids with low concentration (

Structural indicators of asphalt mixtures, including aggregate gradation, spatial distribution, orientation, shape, angularity, texture, aggregate content, asphalt content and air void content, determine mixture heterogeneity and therefore significantly affect the micromechanical response of mixtures. An approach to the virtual design of mixture microstructure using structural indicators is proposed, based on a digital library of realistic aggregates. The methodology comprises three main steps, as follows: (1) a digital library containing almost 3000 reconstructed grains with quantified morphological properties based on computed tomography (CT) imaging is established; (2) aggregates which are consistent with volumetric and morphological assignments are identified in the library as the aggregate component of the mixture; and (3) the positions and orientations of selected aggregates are determined according to their distributional assignment, and consequently, the asphalt mortar and air void components are identified to obtain the microstructure of the virtual mixture. The proposed approach customizes the morphology and spatial distribution of aggregates and the content of the three phases of specimens to simulate the mixture’s microstructure, which facilitates the study of the correlation between the structural indicators and the mechanical responses of mixtures. Numerical simulations of indirect tensile tests were conducted to show different mechanical properties of obtained specimens.

The crashworthiness testing of carbon/epoxy composite tubes is conducted in this study, and the corresponding energy-absorbing parameters and failure morphology are discussed. Considering the anisotropic constitutive relationships of composites, a stiffness degraded model that involves the extended Hashin failure criterion and damage evolution law based on the continuum damage mechanics is proposed to analyze the progressive failure of G803/5224 composite tubes. The progressive failure user subroutine is developed based on the transient dynamics software. The progressive failure numerical analysis combined with the failure criterion is also discussed. The relative error of specific energy absorption and average load is less than 6% compared that of the experimental results. This result indicates that the proposed method can be applied to estimate the energy-absorbing characteristics of composite tubes.

An integrated reaction-separation process based on only solvents is presented, and thus without the need for related technical equipment (reactor-separator). Both product purification and reactant recovery are achieved automatically for an asymmetric aldol reaction employing a biphasic solvent system as compartmentalizing soft matter. Firstly, COSMO-RS based simulation is introduced as a theoretical guidance in the solvent selection for the reactant 3-chlorobenzaldehyde and non-solvent selection for the R-aldol product, (R)-4-(3-chlorophenyl)-4-hydroxybutan-2-one. This encompasses solubility as core critical parameter, as well as chemo-physical properties and environmental profiling. Such criteria-cascaded screening could effectively reduce a 7665 solvents-database into 1 candidate solvent, which is dodecane, before experimental process assessment. Secondly, this screening’s top candidate was validated as the best reaction solvent by first a solubility test and then by a batch reaction, in which a conversion of 69% was achieved. As desired, the mono-phase reaction yielded spontaneously the product layer and the separate dodecane phase as the second layer, which indeed allowed facile separation of the product from the residual reactant. In a third step, a segmented flow process was developed giving a highest product yield of 63% and a total conversion 92% respectively after a 2 h residence time.

Despite remarkable development in high capacity iron oxide-based electrodes for lithium-ion batteries (LIBs), the low mass loading and poor areal capacity still impede their practical applications. In this report, novel FeOx nanoarrays were directly constructed on three-dimensional (3D) copper foam current collector (denoted as CF@FeOx NAs) via facile hydrothermal growth followed by a postannealing process. The nanoarrays were stacked by numerous FeOx porous nanoblocks, exhibiting a unique hierarchical structure. The loading density of FeOx in the CF@FeOx NAs reached 2.5 mg cm–2 owing to the hierarchical structure of the novel 3D nanoarray electrode. When tested as an anode for LIBs, the 3D integrated electrode delivered high areal capacities of 3.33 and 2.61 mAh cm–2 at 0.25 and 1.25 mA cm–2, respectively. A high areal capacity of 2.12 mAh cm–2 was retained at 2.5 mA cm–2 after 500 cycles, which is the best electrochemical performance in terms of areal capacity for the iron oxide-based electrodes reporte...

In recent years, electro-magnetic induction technology has been widely applied in functional asphalt pavements as an in-situ heating method. Most of the existing research focused on incorporating inductive agents in asphalt pavements to improve their induction heating performance (IHP). In addition to electrically conductive asphaltic layers, a new structure of asphalt pavement incorporating magnetically absorbing asphaltic layers is proposed in this research to enhance the IHP. This multi-layer asphalt pavement system is mainly composed of three sub-systems from top to bottom: the upper one made of electrically conductive layers containing waste steel shavings, the middle one is the asphalt mixture layer with the pre-embedded induction coil and the lower one made of magnetically absorbing layers containing waste ferrites to replace the conventional waterproof adhesive layer. The upper part was developed with four different content of waste steel shavings, used as inductive agents in asphalt. Meanwhile, three kinds of magnetically absorbing layers were prepared, including common magnetically absorbing layers and two kinds of asphalt magnetically absorbing layers. Then, the pavement performance test was performed to examine the asphalt magnetically absorbing layers, and the induction heating experiments of the newly formed multi-layer systems were conducted. Heating and energy saving rates were used to evaluate the effect of the content of inductive agents and the magnetically absorbing layers on IHP. Results show that the asphalt magnetically absorbing layers can meet the requirements of the conventional waterproof adhesive layer. It was also found that the optimal IHP was obtained when the content of waste steel shavings was 6%. More interestingly, the common magnetically absorbing layers improve the IHP better than the asphalt magnetically absorbing layers. This means that the addition of asphalt has a negative impact on the magnetic absorption effect.

The morphology of aggregates has a significant effect on the mechanical performance of aggregate-based materials such as asphalt concrete and cement concrete. This paper obtains shape index...

Numerical representations of aggregate particles are critical to reconstruct microstructure of asphalt mixtures. The main objective of this study is to obtain an accurate and automated discrete element method (DEM) with a small number of sphere elements for any real aggregate particle. An automated DEM method was developed based on X-ray computed tomography (CT) images with aid of computer graphics and image processing techniques. The method consists of three main steps. First, or each image layer, two-dimensional (2D) outlines of aggregate particles in cropped image blocks are detected. Second, the mapping between an aggregate particle and its outlines on different layers is established. Based on the aforementioned mapping, the three-dimensional (3D) geometric model of each particle is constructed. Third, the 3D geometric model of the aggregate particle is automatically transformed into its discrete element representation. For each aggregate particle, the fitting accuracy between the 3D geometric...

The mechanical analysis of adhesive repair of honeycomb sandwich composite plate is more complicated than that of the laminated plate repair, because not only the laminated damage, but also the honeycomb buckling should be considered. Experimental and numerical investigations are carried out to understand the damage propagation and ultimate strength of both open-hole and repair plates under compressive load. The results of numerical models are verified by experimental data and they are found in good agreement. It is revealed from the results that the strength of open-hole plate is about 34% of the strength of intact plate, while the strength of repair plate could resume to 76% of that of intact plate after the repair process. It is found that the structure strength increases as the scarf repair angle decreases due to the decline of shear stress in the adhesive. We also present the optimum ply sequence and the optimum number of overlays in considering the improvement of structure strength. This research wi...

Over the past decade, the real-time cell analyzer (RTCA) has provided a good tool to the cell-based in vitro assay. Unlike the traditional systems that label the target cells with luminescence, fluorescence, or light absorption, RTCA monitors cell properties using noninvasive and label-free impedance measuring. However, realization of the maximum value of RTCA for applications will require assurance of within-experiment repeatability, day-to-day repeatability, and robustness to variations in conditions that might occur from different experiments. In this article, the performance and variability of RTCA is evaluated and a novel repeatability index (RI) is proposed to analyze the intra-/inter-E-plate repeatability of RTCA. The repeatability assay involves six cell lines and two media (water [H2O] and dimethyl sulfoxide [DMSO]). First, six cell lines are exposed to the media individually, and time-dependent cellular response curves characterized as a cell index (CI) are recorded by RTCA. Then, the variations along sampling time and among repeated tests are calculated and RI values are obtained. Finally, a discriminating standard is set up to evaluate the degree of repeatability. As opposed to the standardized methodologies, it is shown that the presented index can give the quantitative evaluation for repeatability of RTCA within E-plate and variation on different days.

A series of novel carbamate group-containing quaternary ammonium salts (QASs) have been synthesized, which were subsequently used as antimicrobial agent and incorporated into polyurethane coatings through crosslinking with terpene-based polyol and polyisocyanate. The chemical structures of QASs were characterized by FT-IR, 1H NMR, and 13C NMR. The effects of QASs on the properties of coatings were investigated. The results showed that the resulting coatings exhibited significant antimicrobial activity against both Staphylococcus aureus and Escherichia coli by introducing QASs into the polyurethane networks. Furthermore, with the increasing of QAS content, the antimicrobial activity and adhesion of the coatings were enhanced, while the pencil hardness, water resistance and thermal stability of the coatings were decreased.

The structurally controllable hyperbranched HBPE–CIDAs (HBPE modified with CIDA units) were synthesized by modifying the periphery of the second generation hyperbranched polyester (HBPE) with 1-cyanoindolizine-3-carboxylic acid (CIDA) groups via a one-pot synthesis. The structures and self-assembly behaviors of HBPE–CIDAs were established by combined studies of FFT-IR, NMR, TEM, SEM, AFM and XRD. Furthermore, host–guest recognition of HBPE–CIDAs was investigated by fluorescence studies. The results indicated that the HBPE–CIDA4 nanospindles have weaker response to various metal ions while having better selectivity to anthracene through π–π stacking interactions than the HBPE–CIDA1 nanospheres.

Herein, we reported the synthesis of hyperbranched aromatic–aliphatic co-polyester nanorods HBPE-CICA6 and HBPE-CICA2 by modifying the periphery of second generation hyperbranched polyester (HBPE) with 1-cyano-pyrrolo[2,1-a]isoquinoline-3-carboxylic acid (CICA) groups. Structures of the HBPE-CICAs were confirmed by combined studies of Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR), transmission electron microscopy (TEM), atomic force microscopy (AFM) and X-ray diffraction (XRD). The potential application of HBPE-CICAs in ion recognition was investigated; in particular, HBPE-CICA2 exhibited remarkable selectivity for Fe3+.

In this study, new carbon nanomaterial N-doped carbon dots (NCDs) were obtained via a one-step hydrothermal method using isoleucine and citric acid as carbon precursors. TEM results showed that the NCD diameters were not uniform but distributed in the 6–15 nm range, with an average value of 10 nm. The maximum emission wavelength of the obtained NCDs was 415 nm with an excitation wavelength of 370 nm. Under optimal conditions, the nanoparticle can be used as sensors and exhibited a ‘turn-off’ fluorescence response to Fe 3+ , with a good linear relationship of ( F / F 0 ) versus Fe 3+ over the concentration range of 0–20 μmol/L.

The radial growth of δ-phase in Fe-0.15%C-0.8% Mn steel during solidification was in-situ observed under a high-temperature confocal scanning laser microscope (HTCSLM). The correlation between radial growth rate of cylindrical solid and time in melt was investigated, and the expression was deduced. The results indicate that the radius of cellular δ-phase rapidly enlarges at the beginning, and then the enlargement amplitude gradually declines. The variation of radial growth rate vs time is the same for each cellular δ-phase, and the radial growth rate of δ-phase rapidly declines to about 1.5 μ m/s within 10 s at a cooling rate of 2.7 K/min, after that the growth rate slowly falls. The experimental data of the radial growth rate of cellular δ-phase are consistent with the calculation results for Fe-0.15%C-0.8% Mn steel.

The growth of proeutectoid ferrite in Fe-0. 15%C-0. 8%Mn carbon steel during continuous cooling process was observed in-situ and tracked dynamically by using a high-temperature confocal scanning laser microscope (HTC-SLM), and the growing process was also investigated. The growth regularity of proeutectoid ferrite plates within austenite was obtained by analyzing the growth fashions and directions and quantitatively studying the growth rates. The results show that the proeutectoid ferrite plates grow in the fashion of creeping, twisting, branching off and deflection within austenite grain. The proeutectoid ferrite plates can grow up along preferential orientation but not strictly. Its growth direction fluctuates and changes in a small range. The growth rate also changes with the change in growth fashion and direction. When the proeutectoid ferrite grows in the fashion of deflection, the average growth rate of proeutectoid ferrite before its deflection is about 61. 9, and 46. 2 μm/s after the 15° deflection. At the beginning of proeutectoid ferrite growing, there is a fast growing stage. As the tip of proeutectoid ferrite extends forward continuously, the growth rate will slow down. Therefore, it will induce the proeutectoid ferrite to deflect and grow along another favorable direction, then it will grow rapidly again.

Surface modification of dental implants with biomolecules is of particularly interest recently. To mimic the structure and function of native extracellular matrix (ECM), a derivative of hyaluronic acid (HA), HA-GRGDSP, was synthesized, Arg-Gly-Asp (RGD)-containing collagen (Col)/HA multilayer polyelectrolyte films (MPFs) coating was fabricated on titanium (Ti) through alternate deposition of Col and HA-GRGDSP with 4.5 assembly cycles; moreover, bioactive molecule, basic fibroblast growth factor (bFGF), was also incorporated into such coating. This coating was then carefully characterized using scanning electronic microscope (SEM) and scanning force microscopy (SFM); bFGF release from the coating was also evaluated. (Col + bFGF)/HA-RGD coating was successfully deposited on Ti surface, and about 300 pg of bFGF could be slowly released from this coating for a week. This coating significantly promoted the initial cell attachment of human gingival fibroblasts (HGFs) compared with other groups (p < 0.05), and HGFs adhered and spread better on this coating than other groups (p < 0.05). Regarding cell proliferation and differentiation of HGFs, they were greatly stimulated when cultured on this coating (p < 0.05). These results indicated that surface modification of Ti using biomolecules might improve the sealing between the neck section of a dental implant and the soft tissue.

The behavior of inclusions in the process of δ-phase growth during the solidification of Fe-0. 15C-0. 8Mn steel was in-situ observed using a high-temperature confocal scanning laser microscope (HTCSLM). The results show that inclusions arrive the S/L (solid/liquid) interface by way of direct impact or gradual drift, when the cell spacing is approximately equal to 177 μm during the growth of cellular δ-phase. The inclusions easily stay at the positions of trailing vortex formed by the circumferential motion of molten steel around δ-phase. Some inclusions reaching the S/L interface are captured by the solid-phase. Some of them move along the normal direction of the S/L interface because of pushing of solid-phase, and the others get away from the S/L interface after being pushed for a distance. The faster the growth rates of the solid-phase are, the easier the inclusions are captured by the S/L interface. The slower the growth rates of the solid-phase are, the easier the inclusions move with the S/L interface.

Taking Fe-0.15wt%C-0.8wt%Mn steel as the research object, in situ observations of the δ phase growth process during solidification were conducted by using a high-temperature confocal scanning laser microscope (HTCSLM). The effects of the solid/liquid (S/L) interface’s shape, temperature, and curvature radius on the lateral growth rate of δ phase were investigated in detail, and the relational expression among the lateral growth rate of δ phase, temperature, and curvature radius of column-shaped δ phase was deduced for the carbon steel during solidification. The results indicate the growth rate of the concave-shaped S/L interface is larger than that of the convex-shaped S/L interface during the beginning growth of δ phase, but these two kinds of growth rates gradually approach with proceeding in solidification. The calculated lateral growth rate of δ phase is consistent with the experimental result at a cooling rate of 0.045°C/s.

The lateral wall stabilities during the growing process of cellular crystal in the melt were studied in this article. The dynamics equation of cylindrical solid-liquid interface morphological stabilities in melt was first derived, and then the expression of criterion for cylindrical solid-liquid interface morphological stabilities was defined. The effect of the shape factor, solid radius, and other relevant factors on the morphological stabilities was analyzed. Also, the critical shape factor and critical growth rate for keeping the stabilities of the interface were determined. The phenomenon during the lateral growth process of δ-phase cellular crystal in carbon steel was observed under a high-temperature confocal scanning laser microscope (HTCSLM), which was used to verify the theoretical analysis and calculated results. The results indicate that the shape factor is beneficial to improving the stabilities of the cellular crystal lateral wall. During the increase process of the cellular crystal radius, however, there is a certain value of the cellular crystal radius, which induces the shape factor to reduce stabilities of the cellular crystal lateral wall rapidly. Even if the other conditions are unchanged, the shape of the cellular crystal may also cause the cellular crystal lateral wall to lose its stabilities. There are two critical growth rates to keep the cellular crystal lateral wall growing stably under the conditions of this research. For the Fe-0.15 pct C-0.8 pct Mn alloy, these two critical growth rates are 10−4 and 10 cm/s orders of magnitude, respectively. The difference between them is more than 105 times, so the slow critical growth rate conforms to the actual critical growth rate. The radius of the cellular crystal is the main influencing factor of lateral wall stabilities. The bigger the radius of the cellular crystal is, the worse the stabilities of the lateral wall are. That is also one of the reasons that the fine cellular crystal can survive during a certain period. The results of the theoretical analysis about stabilities of the cellular crystal lateral wall agree well with the lateral growth phenomena of δ phase cellular crystal in carbon steel observed by a HTCSLM. The theoretically calculated results of the radial critical growth rates are coincident with the experimental results.

The microstructure of as-cast state and as-aged of a Cu-0.43Cr-0.22Zr-0.092Mg alloy were analysized by TEM and HRTEM, and the formation mechanics of nanophase during heat treatment were discussed. The research showed that precipitations came from the microstructure of casting alloy which adjacent streak spacing were 1.2nm after aging, which obeyed the Nishyama-Wasserman orientation relationship with the matrix.

The annealing process of 800MPa grade hot dip galvanized DP steel was simulated on Gleeble-1500 thermo-mechanical simulator. The recovery and recrystallization of ferrite and the formation of austenite during the continuous heating process were studied in this paper. The results show that the fine equiaxed recrystallized nucleus started emerging nearby grain boundaries of deformed ferrites when the heating temperature was 630°C. With the increase of temperature, the recrystallized grain began to grow up, some new crystallized nucleus formed in other places with high stored energy of deformation. when the heating temperature was 690°C, the recrystallization process was basically finished, the deformed microstructure had been replaced by equiaxed ferrite grains. When the heating temperature was 730°C, the austenite nucleated on the carbide particles of the ferrite grain boundaries in the original pearlite area mainly. Some austenite also nucleated on the ferrite grain boundaries or the carbide particles within the ferrite grain. When the temperature was 750°C, the austenite began to grow along and parallel to ferrite grain boundaries.

Under the condition that the solid-liquid interface bends periodically in continuous casting, the expression of solid-phase growth rate adapting to continuous casting was set up, and then the growth rates were calculated. On this basis, the morphologic of crystal growth and the variation of primary dendrite spacing during continuous casting slabs were studied. The results show that the growth rate is the fastest when solid-phase moves to wave crest within a deformation periodicity, whereas the growth rate is the slowest when the crystal moves to wave hollow. The bigger the bulge size is, the greater the variation amplitude of the growth rate will become. The variation of the growth rate results in the S/L interface to develop towards a planar surface. Because the value is much smaller than the critical value of the transformation from cells to dendrites, and the crystals only grow in the fashion of dendrites. The primary dendrite spacing at wave crest is bigger than the primary dendrite spacing at wave hollow in early stage of columnar crystal growth, and the dendrite spacing at wave crest is basically equal with the dendrite spacing at wave hollow in the late stage of solidification, and they quickly simultaneous increase. Good correlation is obtained between the experimental results and the calculation results of the dendrite arm spacing.

The tensile process of 800MPa grade dual-phase steel was observed in-situ by SEM. The initiation and propagation of crack in dual-phase steel, the initiation of micro-pores, the deformation behavior of ferrite and martensite were analyzed in this paper. The results show that the main crack goes across the soft ferrite and around the hard martensite during its propagation in the beginning. When the applied stress is small, the micro-pores are easy to form inside the ferrite grain or on the interface of ferrite and martensite. The micro-pores can also form in the fracture site of martensite with the increase of applied stress. The fracture morphology of the dual-phase steel is dimple and the formation of fracture belongs to plastic fracture.

The testing device self-designed was used to measure the shrinkage ratio of Fe-0.18%C alloy in the length direction of cast ingot with the dimension of 200×80×100 mm. The results show that the total linear shrinkage mass of cast ingot is 0.0281 mm in the range of 4 mm near the inner surface of water-cooled crystallizer from the beginning of solidification to the end of δ→γ transformation. The shrinkage mass of δ phase and δ→γ transformation is 0.0211 mm and 0.007 mm, which is 75% and 25% of total shrinkage mass, respectively. The shrinkage rate of δ phase and δ→γ transformation is 0.45 μm·s-1and 1.45 μm·s-1, respectively. The shrinkage mass in the cross section of cast ingot is less than the free shrinkage mass observed by using a confocal laser scanning microscope.

In situ observation of growth process of high temperature phase in 0.15% C carbon steel during solidification concerned with using Confocal Scanning Laser Microscope (CSLM), the growth rate of -phase has been measured. The results indicate that high temperature -phase grows at cell crystal way when the cooling speed reaches 2°C/min in 0.15% C carbon steel. The -phase of round or oval cross-sectional shaped may grow stably. The growth rate of -phase is gradually getting slow along with increasing of curvature radius. The variation of growth speed tends to be similar with different solid-liquid interface shapes of -phase. The growth rate of concave solid-liquid interface is faster than that of convex solid-liquid interface for phase. The smaller radius of curvature of phase is, the faster the growth rate reaches.

An efficient photoanode based on CdS nanorod@SnO2 nanobowl (CdS NR@SnO2 NB) arrays is designed and fabricated by the preparation of SnO2 nanobowl arrays via nanosphere lithography followed by hydrothermal growth of CdS nanorods on the inner surface of the SnO2 nanobowls. A photoelectrochemical (PEC) device constructed by using this hierarchical CdS NR@SnO2 NB photoanode presents significantly enhanced performance with a photocurrent density of 3.8 mA cm-2 at 1.23 V versus a reversible hydrogen electrode (RHE) under AM1.5G solar light irradiation, which is about 2.5 times higher than that of CdS nanorod arrays. After coating with a thin layer of SiO2 , the photostability of the CdS NR@SnO2 NB arrays is greatly enhanced, resulting in a stable photoanode with a photocurrent density of 3.0 mA cm-2 retained at 1.23 V versus the RHE. The much improved performance of the CdS NR@SnO2 NB arrays toward PEC hydrogen generation can be ascribed to enlarged surface area arising from the hierarchical nanostructures, improved light harvesting owing to the NR@NB architecture containing multiple scattering centers, and enhanced charge separation/collection efficiency due to the favorable CdS-SnO2 heterojunction.

Graphene decorated with hierarchical CuS nanoplates (CuS NP-G) was synthesized using a microwave method to be used as a photocatalytic material. The incorporation of graphene into hierarchical CuS nanoplates was confirmed by structural, morphological and optical characterizations. The photocatalytic performance of the nanocomposite was evaluated. This study confirmed that the introduction of graphene was an effective way not only to improve the structural stability and service durability of the composite, but also to improve its solar photocatalytic activity by promoting the electron transfer and charge separation of hierarchical CuS nanoplates.

The microstructure evolution of 1 000 MPa cold rolled dual-phase (DP) steel at the initial heating stages of the continuous annealing process was analyzed. The effects of different overaging temperatures on the microstructures and mechanical properties of 1 000 MPa cold rolled DP steel were investigated using a Gleeble–3500 thermal/mechanical simulator. The experimental results show that ferrite recovery and recrystallization, pearlite dissolution and austenite nucleation and growth take place in the annealing process of ultra-high strength cold rolled DP steel. When being annealed at 800 °C for 80 s, the tensile strength and total elongation of DP steel can reach 1 150 MPa and 13%, respectively. The microstructure of DP steel mainly consists of a mixture of ferrite and martensite. The steel exhibits low yield strength and continuous yielding which is commonly attributed to mobile dislocations introduced during cooling process from the intercritical annealing temperature.

Using the standard solid state reaction method, SrBi4 − 2x/3Ti4 − x W x O15(SBWT-x, x = 00.06) ceramic samples were synthesized. It is found that W doping does not change the crystal structures of SrBi4Ti4O15 and their ferroelectric, dielectric and piezoelectric properties were investigated. The remnant polarization (2P r ) of the samples, which varies with x, has a maximum value of 25.4 μC/cm2 when x = 0.03, that is nearly 60% greater than that at zero doping. Meanwhile, the E c only varies a little upon W substitution. The largest shift of T c is below 6%, which suggests that the good thermal stability is almost not deteriorated by W-doping. The piezoelectric constant d 33of SBWT-x increases at first, then decreases with W doping. The d 33 reaches a maximum value of 15pC/N, when x is 0.03. The d 33 increases by about 50% compare with that of SrBi4Ti4O15. It coincides with the variation of 2P r of the SrBi4 − 2x/3Ti4 − x W x O15.

In view of the periodic bending deformation of solid-liquid interface in the solidification process for continuous casting slab, the variation of temperature gradient and dendritic spacing in the front edge of the solid-liquid interface, and the nucleation and propagation process of crack were studied. It is shown that the bending deformation of the interface results in the temperature field change in the front edge of solid-liquid interface, and the occurrence of temperature gradient along drawing direction results in the growth of secondary dendrites. The initial crack formed during the middle and final stage of solidification may extend to the surface of the casting slab and become an internal crack. The results of the theoretical analysis are basically in agreement with that of the experiment.

An investigation on the ferroelectric and dielectric properties of higher-valent-cations Nb-and Mo-modificated SrBi4Ti4O15 ceramics was presented. The ferroelectric property of SrBi4Ti4O15 was both obviously improved by niobium and molybdenum doping. The remnant polarization (2P r ) of both Nb-and Mo-modificated SrBi4Ti4O15 increases at first, then decreases with further doping. As the doping content is 0.03 and 0.06 respectively, the 2P r maximizes at a value of 24.7 μC/cm2 and 26.5 μC/cm2, which is about twice larger than that of SrBi4Ti4O15. Meanwhile, the coercive field is increased less than 20% upon Nb and Mo substitution. The Curie temperature of the samples shifted hardly by Nb-and Mo-doping, which indicates that the good thermal stability of SrBi4Ti4O15 is not affected.

An investigation of the ferroelectric and dielectric properties of niobium-doped SrBi4Ti4O15 (SrBi4−x/3Ti4−xNbxO15, x = 0.00, 0.003, 0.012, 0.03, 0.06) ceramics was presented. The ferroelectric property of SrBi4Ti4O15 was improved by niobium doping. The remanent polarization (2Pr) increases at first, then decreases with the increase in niobium content, while the coercive field changes little with Nb-doping. As the niobium content is 0.03, the 2Pr maximizes at a value of 24.7 µC cm−2, which is increased by about 60% in comparison with that of SrBi4Ti4O15. The Curie temperature of the samples hardly varies upon Nb-doping, which indicates that the good thermal stability of SrBi4Ti4O15 does not deteriorate after Nb addition.

An efficient mechanically activated solvent-free synthesis of 1,3,5-triaryl-2-pyrazolines from chalcones and phenylhydrazines using high speed ball milling is described. This method has notable advantages in terms of good yield, short reaction time and neat conditions.