We put forward a method of rapid preparation of chloride selective electrode (Ag/AgCl electrode) by dipping silver wire into sodium hypochlorite solution. The electrodes were prepared through different immersion time. The properties of the electrodes, such as Nernst response, response time and long-term stability, were tested in simulated concrete pore solutions (SCPS). Moreover, the surface morphology of the electrodes was also detected after immersion in solutions over three months. The experimental results reveal that the Ag/AgCl electrode with the fabrication time of 20 minutes (E-20) which is recommended to work as the chloride ion selective electrode has the best performance. Compared to that fabricated by the electrolytic process (E-EP), E-20 can be manufactured in mass. The method has almost the same good performance of Nernst response as E-EP, and has a better response time which is less than 25 seconds. The method also shows a better good long-term stability in SCPS containing chloride ions over three months.

The p-type Ge doped Fe_0.4Co_3.6Sb_12-xGe _x skutterudites with multi-scaled impurity dots (500 nm-2 mm) were successfully prepared by using melt-quenching (MQ) and subsequent spark plasma sintering (SPS) technique. Compared with traditional method, the new technology significantly shortened the processing time from several days to less than 24 hours. The phase of impurity dots was demonstrated to be CoSb through analysis of X-ray diffraction (XRD) and energy-dispersive spectrum (EDS). Impurity dots were induced by Ge substitution of Sb in the non-equilibrium synthesized process. Due to the abandonment of the long reaction of annealing crystallization, a few of Ge atoms would fail to substitute Sb site of skutterudite in this non-equilibrium synthesized process, leading to that the multi-scaled impurity dots randomly distributed in the matrix of skutterudite Fe_0.4Co_3.6Sb_12-xGe _x. The combination of multi-scaled impurity dots scattering long wavelength heat-carrying phonons and the point defect scattering short and middle wavelength heat-carrying phonons dramatically made the 22.2% reduction of lattice thermal conductivity. As a result, compared with unsubstituted sample of Fe_0.4Co_3.6Sb₁₂, the maximum ZT value was increased by 30.5%. Thus, the two marked features of this new synthesis process, the shortened preparation time and the enhanced thermoelectric performance, would make a promising commercial application in the future.

In order to explore the effect of high-temperature annealing on the mechanical performances and microstructures of different oxygen SiC fibers, two types of silicon carbide (SiC)-based fibers, specified as XD-SiC fibers (low oxygen) and Nicalon-201 fibers (high oxygen), were annealed in Ar for 1 h at 800 °C, 1 000 and 1 200 °C, respectively. Mechanical properties of these fibers were characterized via a monofilament tensile method, with observation of the damaged monofilament by SEM. Also, the effects of annealing on the microstructure and chemical compositions of the fibers were studied. The experimental results indicated that the tensile strength decreased with the increase of annealing temperatures, after annealing-treatment at 1200°C, D-SiC fibers remained 84% of its original strength, while Nicalon-201 fibers remained only 58% of its original strength. Crystallization and chemical composition of the fibers are the dominating factors for their mechanical performance at high temperatures. The microstructure changes of XD-SiC fibers are mainly composed of the growth of β-SiC, for Nicalon-201 fibers, evaporation of gases is the main change for microstructure.

The preparation of SiBNC ceramic oxidation-resistant coating on carbon fiber via precursor-solution infiltration and pyrolysis (PIP) method was presented and discussed in detail. Moreover, the microstructures and the components of the coating were characterized. The experiment results showed that the 0.5% polyborosilazane (PBSZ) solution in the coating preparation gave fewer defects, in contrast with the 1% and the 5% PBSZ solutions. The strength of the carbon fiber coated with SiBNC-0.5wt%(3.08GPa) was decreased by 12%. Compared with uncoated carbon fiber, the starting oxidation temperature and the reaction activation energy of the coated carbon fibers (SiBNC-0.5wt%) have increased by about 300 °C and 104%, respectively. The oxidation resistance of the SiBNC coated carbon fiber was improved dramatically.

We prepared the nano-inorganic phase-change “alloy” materials through the modification of Na₂SO₄•10H₂O using Na₂HPO₄•12H₂O and GO nano-nucleating agent, and further investigated their thermophysical properties such as melting/solidification temperatures and enthalpies via differential scanning calorimetry. When the weight ratio of Na₂SO₄•10H₂O and Na₂HPO₄•12H₂O was 8:2 and the weight ratio of graphene oxide was 0.5% of phase change material, the phase change “alloy” material showed excellent performances, specifically, the melting temperature and latent heat were found to be 22 °C and 190 J/g with a degree of subcooling decreased from 8.6°C to 2.1°C. In order to extend the application of the phase change “alloy” material to building energy saving field, it was adsorbed on expanded glass beads under vacuum and further covered with diatomite. When the adsorption rate of EGB (volume) and PCAM (weight) was 2.5:1, the particle size of diatomaceous earth was found to be 3.6μm, while the best packaging result was obtained with the melting temperature and latent heat being 21°C and 135J/g, and no leakage was observed.

Gaskets are applied in PEMFCs (proton exchange membrane fuel cells) to keep reactant gases and liquid within their respective regions, which are of great significance for the both sealing and electrochemical performance of fuel cells during the long-term operation. In this study, the degradation of silicone rubbers, often selected as seals in PEMFCs, in Fenton’s reagents with different H₂O₂ concentrations was investigated. The changes in chemical properties, mechanical behavior and surface morphology of the samples were studied before and after exposure to the test environment over time. It is found that increasing H₂O₂ concentration will degrade the rubbers more severely. The experimental results elucidate the degradation mechanism of silicone rubbers in Fenton’s reagents and the influence of H₂O₂ in the degradation process.

Bi_0.5Sb_1.5Te₃/Cu core/shell powders were prepared by electroless plating and hydrogen reduction, and then sintered into bulk by spark plasma sintering. After electroless plating, with increasing the Cu content, the electrical conductivity keeps enhancing significantly. The highest electrical conductivity reaches 3341S/cm at room temperature in Bi_0.5Sb_1.5Te₃ with 0.67wt% Cu bulk sample. Moreover, the lowest lattice thermal conductivity reaches 0.32 W/m·K at 572.2 K in Bi_0.5Sb_1.5Te₃ with 0.67wt% Cu bulk sample, which is caused by the scattering of the rich-copper particles with different dimensions and massive grain boundaries. According to the results, the ZT values of all Bi_0.5Sb_1.5Te₃/Cu bulk samples have improved in a high temperature range. In Bi_0.5Sb_1.5Te₃ with 0.15wt% Cu bulk sample, the highest ZT value at 573.4 K is 0.81. When the Cu content increases to 0.67wt%, the highest ZT value reaches 0.85 at 622.2 K. Meanwhile, the microhardness increases with increasing the Cu content.

Nano-spherical Co²⁺-doped FeS₂ was synthesized through a simple solvothermal method. The products were investigated using XRD, FE-SEM, BET, ICP, EDS, TEM, HRTEM, XPS, and UV-vis spectroscopy. The results indicated that Co²⁺ ion could change the particle nucleation process and inhibited the particle growth of FeS₂. In addition, when the content of doped Co²⁺ was 15%, the degradation efficiency of methylene blue (MB) achieved 60.72% after 210 min irradiation, which increased by 52.01% than that of the undoped FeS₂. Moreover, comparison experiments also demonstrated that the M (M=Co²⁺, Co²⁺/Ni²⁺)-doped FeS₂ photocatalytic activity efficiency sequence was Co²⁺ > Ni²⁺>Co²⁺/Ni²⁺. This is ascribed to the fact that the Co²⁺ doping could induce the absorption edge shifting into the visible-light region and increased the surface area of the samples. The effect mechanisms of M-doping on the band gap and the photocatalytic activity of FeS₂ were also discussed.

The La-Mg-Ni-Mn-based AB₂-type La_1-xCe _xMgNi_3.5Mn_0.5 (x = 0, 0.1, 0.2, 0.3, and 0.4) alloys were fabricated by melt spinning technology. The effects of Ce content on the structures and electrochemical hydrogen storage performances of the alloys were studied systematically. The XRD and SEM analyses proved that the experimental alloys consist of a major phase LaMgNi₄ and a secondary phase LaNi₅. The variation of Ce content causes an obvious change in the phase abundance of the alloys without changing the phase composition. Namely, with the increase of Ce content, the LaMgNi₄ phase augments and the LaNi₅ phase declines. The lattice constants and cell volumes of the alloys clearly shrink with increasing Ce content. Moreover, the Ce substitution for La results in the grains of the alloys clearly refined. The electrochemical tests showed that the substitution of Ce for La obviously improves the cycle stability of the as-spun alloys. The analyses on the capacity degradation mechanism demonstrate that the improvement can be attributed to the ameliorated anti-corrosion and anti-oxidation ability originating from substituting partial La with Ce. The as-spun alloys exhibit excellent activation capability, reaching the maximum discharge capacities just at the first cycling without any activation treatment. The substitution of Ce for La evidently improves the discharge potential characteristics of the as-spun alloys. The discharge capacity of the alloys first increases and then decreases with growing Ce content. Furthermore, a similar trend also exists in the electrochemical kinetics of the alloys, including the high rate discharge ability (HRD), hydrogen diffusion coefficient (D), limiting current density (I _L) and charge transfer rate.

A three-dimensional dynamic model for nano/micro-fabrications of silicon was presented. With the developed model, the fabrication process of silicon on nothing (SON) structure was quantitatively investigated. We employ a diffuse interface model that incorporates the mechanism of surface diffusion. The mechanism of the fabrication is systematically integrated for high reliability of computational analysis. A semi-implicit Fourier spectral scheme is applied for high efficiency and numerical stability. Moreover, the theoretical analysis provides the guidance that is ordered by the fundamental geometrical design parameters to guide different fabrications of SON structures. The performed simulations suggest a substantial potential of the presented model for a reliable design technology of nano/micro-fabrications.

Silicon nitride ceramics were prepared by means of a hot-press sintering method. The ablation behavior was studied by plasma wind tunnel tests. The data suggested that, under low heat flux and stagnation pressure conditions, the ablation process was controlled by the atomic oxidation of Si₃N₄, leading to the elimination of Si₃N₄. By contrast, the erosion was mainly produced by the decomposition of Si₃N₄ under high heat flux and stagnation pressure conditions. Under these conditions, a fraction of Si phase, formed upon decomposition of Si₃N₄, was volatilized. The remained Si had melted due to high temperatures and scoured away from stagnation point area, generating mushroom-shaped samples.

The influences of surfactant type and concentration on the content and uniformity of SiC particles in Ni-SiC deposit were studied in this paper. The electrochemical behavior of preparing Ni-SiC composite coating was investigated using the cyclic voltammetry method. Then the impact of surfactants on the deposition potential of Ni-SiC coating was analyzed. Electrochemical studies showed that the cathode overvoltage increases gradually with increasing SDS (Sodium dodecyl sulfate) concentration. The CV curve showed the shift towards a lower current at a given potential with increasing SDS concentration. Ni-SiC composite coatings were prepared by electrodeposition. The experimental results show that the dispersion of 40nm SiC in Ni-SiC coating obtained in the electrolyte containing SDS is superior that containing CTAB (cetyltrimethyl ammonium bromide). CTAB increases the content of 40 nm SiC particles in the Ni-SiC coating, but the uniformity of 40 nm SiC particles in Ni-SiC composite coating is poor. SiC particles are still agglomerated. Compared with the anionic surfactant SDS and the cationic surfactant CTAB, surfactant SDS makes the particles better dispersed. But the contribution of surfactant SDS for co-deposition amount of SiC particles is negligible. The cationic surfactant CTAB can effectively improve the suspension performance of SiC particles and promote the co-deposition of SiC particles and metallic nickel. But there is still some reunion of SiC.

Nano hafnium carbide (HfC) powders were synthesized by sol-gel combining high-temperature rapid heat treatment process using citric acid and hafnium tetrachloride as the raw materials. The effects of ball milling treatment on the phase and morphology of pyrolysis products (HfO₂-C) and final HfC product were investigated and the influences of heat treatment temperature and holding time on the structure and properties of the synthesized hafnium carbide powders were also studied. The experimental results showed that the HfO₂-C powders with good uniformity and small particle size were prepared by controlling the milling time. Pure HfC powders with an average particle size of 500 nm were obtained at 1 700 °C with a holding time of 3 min, and the oxygen content was about 0.69wt%, lower than that of the hafnium carbide powders prepared by SPS (0.97%).

Three-dimensionally ordered (3DOM) macroporous phosphotungstic acid/SiO₂ (HPW/SiO₂) materials were prepared by using colloidal crystal as templates and applied for oxidative desulfurization (ODS) of the model fuel oil. The obtained HPW/SiO₂ materials were characterized through scanning electron microscopy, powder X-ray diffraction, N₂ sorption, and Fourier transform infrared spectroscopy. The results indicated that 3DOM HPW/SiO₂ possessed hierarchical pore architectures which contained ordered macropores and disordered mesopores, with the Keggin type HPW embedded in the framework of pore structure. The removal rate of dibenzothiophene (DBT) could reach 100% under the optimum conditions, moreover. The performance was only slightly decreased for the regenerated catalyst after 7 cycles.

The effects of the annealing process on the mechanical properties and crystallization behaviors of polypropylene random copolymer (PP-R) composites were investigated using differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM). The experimental results indicated that the annealing process significantly influenced the comprehensive properties of PP-R composites. At temperatures below 23 °C, the impact strength of the PP-R composites annealed at 120 °C for 6 h was relatively high at 74.73 kJ/m², which was 16.8% higher than that of the samples annealed at 80 °C for 6 h. At low temperatures (-30-0 °C), the impact strength ranged from approximately 13.31 kJ/m² to 54.4 kJ/m². In addition, the annealing process conducted at 120 °C for 6 h improved the crystalline structure and low-temperature toughness of the PP-R composites and induced α-form to β-form crystal transformation. The work provides a possible method to reinforce and toughen the semicrystalline polymer at low temperatures (-30-0 °C) by annealing.

The crystal structure, band structure, density of states, Mulliken charge, bond population and optical properties for LiBi_1-xM _xO₃ (M=V, Nb, and Ta) were investigated using hybrid density functional theory. It was found that LiBiO₃ doped with V, Nb, and Ta presented distinctly stronger covalent interactions in M-O (M=V, Nb, and Ta) than Bi-O, thus resulting in mild distortion of the structure and facilitating the separation of photogenerated carriers. Furthermore, the hybridizations of Bi-6s, M-d (M=V, Nb, and Ta) and O-2p widened the valence and conduction bands, which promoted transmission of photogenerated carriers in the band edge and thus caused better photocatalytic performance.

Metal ions like Fe(III) were testified to be efficient co-photocatalyst in the field of environmental governance. Hence, a series of BiPO₄/Fe(III) materials were prepared via a hydrothermal method and impregnation. The experimental results indicated that normal organic dye was effectively removed by BiPO₄ with the presence of Fe(III) as a co-photocatalyst. The enhanced removal mechanism was attributed to the easy transfer of photo-induced electron-hole pairs and relatively high productivity of active redical by synergism of Fe(III).

A modified co-precipitation method for the production of Cu/ZnO/Al₂O₃ complex was studied. The modification was that part of Al was introduced by adding Al³⁺ into Cu²⁺/Zn²⁺ solution, and the rest of Al was added after co-precipitation step in the form of pseudo-boehmite. The prepared samples were characterized by different techniques such as X-ray diffraction, N₂ adsorption, H₂-N₂O titration, temperature programmed reduction and scanning electron microscopy. X-ray diffraction characterizations revealed that Al³⁺ can be doped in aurichalcite lattice, and the maximum doping amount of Al³⁺ was 5.0% of total Cu and Zn atoms. The Cu/ZnO/Al₂O₃ sample produced by the modified method, in which co-precipitated Al³⁺ was 2.5% of total Cu and Zn atoms showed much better activity and stability in water-gas shift reaction than commercial sample. The high Cu surface area (26.1 m²/g) obtained by decompositon of doped aurichalcite is believed to be responsible for the activity enhancement. The stability was enhanced mainly because of the support effect of γ-Al₂O₃, which was decomposed from pseudo-boehmite in the calcination step.

To improve the performance of ultrasonic transducer, the samples of PZT were improved by doping. The doped PZT was observed and analyzed from the following aspects: the crystal phase structures, the surface morphologies and the dielectric constant. According to the transducer parameter requirements for ultrasonic machining, there are also requirements for the parameters of piezoelectric ceramics. The high performance PZT was prepared by doping the elements of Ga, Ba, Nb, Sn, and Sr in PZT. The doped PZT is suitable for power ultrasonic machining at 20 kHz through analysis using X-ray diffraction (XPD), a scanning electron microscope (SEM) and LCR meter. Therefore, the excellent performance of transducer for power ultrasonic machining is guaranteed.

The Lap-joint configuration and the vacuum assisted forming method were put forward to meet the demands of the compression bending strength and the strong connection between the steel and FRC. The bending mechanic tests of the Lap-joint bending specimens carried out, the fabricate processing stability, limit carrying capacity and failure modes were analyzed. The experimental results show that the fabricate processing of the Lap-joint is stable; the bending stiffness is 19.5 N/mm, and the limit bending moment reaches 318 N∙m. The main failure modes are the failure of core material at junction of sandwich plate and steel, and the bending failure in the position of the inner and outer surface.

Cement raw meal with MSS and different heavy metals was blended to examine the fixation ratios, chemical species, and cement crystalline phases in clinkers. The results showed that blending MSS could decrease the fixation ratio of Cr, Ni, Cu, and Zn in the produced clinker by 5% to 25%. And Cr, Cu, and Zn were mainly incorporated into clinkers as metal silicates, Ni was mainly solubilized in MgO to form magnesium nickel oxides, and the transition phases were mainly metal aluminum oxides as indicated by X-ray diffraction. The reduction of fixation ratios was likely attributed to the presence of impure elements, such as sodium and phosphorus in MSS. In addition, high concentrations (eg, 1.7wt%) of chlorine in MSS led to metal chloride formation that could vaporize Cu, Cr, Ni, and Zn. To summarize, introducing MSS would decrease the fixation ratios of heavy metals due to the presence of impure elements, such as sodium and phosphorus and chlorine.

The mechanical and thermal properties of steel reinforced concrete columns with CFRP reinforcement were examined after exposure to a high temperature of 500 ºC. The concrete made with normal and recycled coarse aggregate (RCA) was fabricated and three different RCA replacement ratios (0, 50%, and 100%) were investigated. The fatigue properties of steel reinforced concrete with RCA and CFRP reinforcement were tested for two million cycles at a frequency of 2.5 Hz. The test results show that the failure of strengthened specimens is mainly caused by rupture of CFRP jacket and buckling of inner section steel reinforcement. However, for the unstrengthened specimen, both of inner steel buckling and core concrete cracking are the main contributors to the damage. The load-bearing capacity, deformation and energy dissipation of the specimens during the fatigue test could be strengthened greatly by CFRP reinforcement. However, the CFRP reinforcement has little influence on the improvement of the stiffness of the specimens, which may be caused by a plastic damage accumulation during the early cycles of fatigue tests. Finally, a static test was conducted on the post-fatigue specimens, the results showed that a large decrease in stiffness was observed for the specimens subjected to high temperature and fatigue, and the fatigue loading had a higher influence on the specimens than the high temperature.

To evaluate the effect of pulse parameters on the formation of electrodeposits in concrete cracks, five different types of pulse current were set up, and ZnSO₄ and MgSO₄ solutions were used as the electrolytes. The rate of weight gain, rate of surface coating, rate of crack closure and crack filling depth were measured. Scanning electron microscopy was used to assess the morphology of the electrodeposits, and energy dispersive spectroscopy was used to analyze the mineral composition of the electrodeposits in the cracks. The experimental results demonstrate that, among five different pulse parameters, when T _on/T _off=0.8 ms/0.8 ms, the healing effect of electro-deposition is the best. The pulse mode hardly affects the mineral composition of the electrodeposits but changes the micromorphology. In addition, for both ZnSO₄ and MgSO₄ solutions, when T _on/T _off=0.8 ms/0.8 ms, the crystal structure of the electrodeposits is the most uniform and the densest.

Four cellulose ethers (CEs) were compared for their effects on the pore structure of cement paste using mercury intrusion porosimetry. The experimental results show that the total pore volume and porosity of cement pastes containing the four cellulose ethers are significantly higher than that of the pure cement pastes and the total pore volume and porosity of cement pastes containing HEC (hydroxyethyl cellulose ether) or low viscosity cellulose ethers are low in four CEs. By changing the surface tension and viscosity of liquid phase and the strengthening of liquid film between air voids in cement pastes, CEs affect the formation, diameter evolution and upward movement of air voids and the pore structure of hardening cement paste. For the four CEs, the pore volume of cement pastes containing HEC or low viscosity cellulose ethers is higher with the diameter of 30–70 nm while lower with the diameter larger than 70 nm. CEs affect the pore structure of cement paste mainly through their effects on the evolvement of the small air voids into bigger ones when the pore diameter is below 70 nm and their effects on the entrainment and stabilization of air voids when the pore diameter is above 70 nm.

Due to the intrinsic nature of a heterogeneous and anisotropic microstructure of cement based materials and the small indentation size, the measured microhardness values are subject to considerable variability. This work presents an in-depth assessment of microhardness of hardened cement pastes (HCPs) from a statistical perspective. Hundreds of microhardness measurements were conducted on an HCP sample using a Vickers Microhardness Tester. The results showed that the microhardness measured from the HCP sample significantly scattered with a large standard deviation, varying from tens to hundreds. The data-set of microhardness values was not normally distributed but fit best with a three-parameter lognormal model. By using a statistical software, the probability density function of the microhardness distribution can be readily obtained. The arithmetic mean and its 95% confidence intervals of the measured microhardness values can be used to best represent the microhardness characteristics of HCPs.

Molecular structures of polycarboxylate (PCE) superplasticizer significantly affect the rheological properties of cement paste. Consequently, we employed self-synthesized PCE copolymers with different carboxylic densities to investigate their influence on the rheological behavior of cement paste. Three typical rheological models were applied to analyze the rheological properties, including Power-law model, Bingham model as well as Herschel-Buikley model. In addition, the thixotropical performances of cement paste in the presence of PCE with different carboxylic densities were investigated. The results show that the carboxylic density of PCE greatly influences the dispersing performance of PCE superplasticizers. As carboxylic density increases, the dispersing capability of PCE improves, and P(PEG1-AA6) possesses the strongest dispersing capability, the initial fluidity and 1 h fluidity of cement paste are both the highest, and cement paste has the lowest viscosity and the smallest hysteresis loop.

Cu-Zr-Al-(Y, Ag) amorphous alloy ribbons of Cu₅₀Zr₄₂A_l8, Cu₄₆Zr_47-xAl₇Y _x(x=2, 5), Cu₄₃Zr₄₂Al₈Ag₇, and Cu₄₃Zr₄₂Al₈Ag₅Y₂ were prepared using the single roller melt-spinning method. The glass forming ability and non-isothermal crystallization behavior of the amorphous alloys were investigated by means of X-ray diffraction (XRD) and differential scanning calorimetry (DSC) in a continuous heating mode. The experimental results show that the glass forming ability and thermal stability of Cu-Zr-Al amorphous alloys are improved by adding minor amounts of Y and Ag, and the effect of Ag on the glass forming ability is more significant than that of Y. Compared to the Cu₅₀Zr₄₂A_l8 alloy, the width of the supercooled liquid region of the Cu₄₆Zr_47-xAl₇Y _x(x = 2 and 5) alloys increased by 19 K and 30 K, respectively. The reduced glass transition temperature (T _rg) and the parameter γ of the two alloys enhanced separately. Compared to the Cu₅₀Zr₄₂A_l8 alloy, the T _rg and γ values of both Cu₄₃Zr₄₂Al₈Ag₇ and Cu₄₃Zr₄₂Al₈Ag₅Y₂ alloys enhanced noticeably up to 0.619, 0.417, and 0.609, 0.412, respectively. The crystallization activation energies of the amorphous alloys calculated by the Kissinger and Flynn Wall Ozawa equations increased with the addition of minor Y and Ag into the Cu₅₀Zr₄₂A_l8 alloy. The addition of Y and Ag significantly improved the thermal stability of the Cu₅₀Zr₄₂A_l8 amorphous alloy.

The lap joints of Fe-based metallic glass ribbons were carried by resistance spot welding, and the microstructures of spot welds were investigated by X-ray diffraction and transmission electron microscopy. The results indicated that the perfect formations of joints without typical defects such as spatter were achieved with optimized parameters. Except for little nano-particle Fe₂B, no other crystalline particle was detected by TEM, revealing that the most microstructure in spot weld remains amorphous. The maximum tensile-shearing force was 45.0 N with the optimized parameters of 1 kA weld current, 30 N electrode force and 0.02 ms weld time. The spot weld failed as pullout failure mode propagating along the interface of nugget zone. The study demonstrates that resistance spot welding is an effective and practical welding process for Fe-based metallic glass.

Wear-resistant cladding plates consisting of a substrate (Q345R) and a clad layer (BTW1) were bonded through hot rolling at the temperature of 1 200 °C and a rolling speed of 0.5 m/s. The microhardness of the cladding plate was also tested after being heat treated. The microstructure evolution on the interface of BTW1/Q345R sheets under various reduction rates was investigated with a scanning electron microscope (SEM) and EBSD. It is found that the micro-cracks and oxide films on the interface disappear when the reduction is 80%, whereas the maximum uniform diffusion distance reaches 10 μm. As a result, a wide range of metallurgical bonding layers forms, which indicates an improved combination between the BTW1 and the Q345R. Additionally, it is discovered that the unbroken oxide films on the interface are composed of Mn, Si or Cr at the reductions of 50% and 65%. The SEM fractography of tensile specimen demonstrates that the BTW1 has significant dimple characteristics and possesses lower-sized dimples with the increment in reduction, suggesting that the toughness and bonding strength of the cladding plates would be improved by the increase of reduction. The results reveal that a high rolling reduction causes the interfacial oxide film broken and further forms a higher-sized composite metallurgical bonding interface. The peak microhardness is achieved near the interface.

Si-Al-Y co-deposition coatings were prepared on Ti-Al alloy by pack cementation processes at 1 050 °C for 4 h with different halide activators in the packs for enhancing the high temperature oxidation resistance of Ti-Al alloy. The structure, constituent phases, formation process and oxidation behavior of the coatings were investigated. The experimental results showed that the coatings prepared respectively with NaF and NH₄Cl as activators were composed of a (Ti, X)₅Si₄, (Ti, X)₅Si₃(X represents Nb and Cr), and TiSi₂ outer layer, a TiAl₂ inner layer and an Al-rich interdiffusion zone. However, the constituent phases changed into TiSi₂ in the outer layer and (Ti, X)₅Si₄ and (Ti, X)₅Si₃ phases were observed in the middle layer of the coating prepared with AlCl₃•6H₂O activator. Among the halide activators studied, the coating prepared with AlCl₃•6H₂O was thicker and denser, which is the only suitable activator for pack Si-Al-Y co-deposition coatings on a Ti-Al alloy. The oxidation results show that the coating can protect the Ti-Al alloy from oxidation at 1000 °C in air for at least 80h. The excellent oxidation resistance of the coating is attributed to the formation of a dense scale mainly consisted of TiO₂, SiO₂ and Al₂O₃.

A novel quaternized-chitosan-modified reduced graphene oxide (HACC-RGO) combined the adsorption advantages of RGO and 2-Hydroxypropyltrimethyl ammonium chloride chitosan (HACC). The adsorption property of HACC-RGO sheets for methyl orange (MO) was demonstrated and compared with RGO and HACC. The removal ratios of HACC-RGO sheets reached 92.6% for MO after a 24 h adsorption. The adsorption kinetics, isotherms and thermodynamics were investigated to indicate that the kinetics and equilibrium adsorptions were well-described by pseudo-second-order kinetic and Freundlich isotherm model, respectively. The thermodynamic parameters suggested that the adsorption process was spontaneous and endothermic in nature. Moreover, monodisperse HACC-RGO/CS beads were fabricated by the microfluidic method. The adsorption and desorption of HACC-RGO/CS beads for MO were studied. After three adsorption-desorption cycles, the adsorption capacity remained above 55% and the desorption capacity was not below 70%. The HACC-RGO/CS beads can be reused and have great potential applications in removing organic dyes from polluted water.

The bi-functional carbazole-based photorefractive polyphosphazenes with different content of C₆₀-doped were fabricated. The glass transition temperature (T _g) of these polymer composite materials was determined using a differential scanning calorimetric (DSC) method. According to the DSC measurement results with different heating rates, the variation of T _g and the active energy of glass transition (E _g) were analyzed in detail. The analysis results indicate that the transition region shifts to higher temperatures with increasing heating rate, and C₆₀ content (below 1.0wt%) can influence the T _g of photorefractive polyphosphazenes. The T _g first increases and then decreases with the C₆₀ content (below 1.0wt%). The probable causes of the influence of C₆₀ on T _g was proposed.

Polyurethane polymer grouting materials were studied with conventional triaxial tests via the particle flow code in two dimensions (PFC_2D) method, and the simulation results agreed with the experimental data. The particle flow code method can simulate the mechanical properties of the polymer. The triaxial cyclic loading tests of the polymer material under different confining pressures were carried out via PFC_2D to analyze its mechanical performance. The PFC_2D simulation results show that the value of the elastic modulus of the polymer decreases slowly at first and fluctuated within a narrow range near the value of the peak strength; the cumulative plastic strain increases slowly at first and then increases rapidly; the peak strength and elastic modulus of polymer increase with the confining pressure; the PFC_2D method can be used to quantitatively evaluate the damage behavior of the polymer material and estimate the fatigue life of the materials under fatigue load based on the number and the location of micro-cracks. Thus, the PFC_2D method is an effective tool to study polymers.

The gradient copolymers of acrylic acid and trifluoroethyl methacrylate (coded as P(TFEMA-grad-AA)) were synthesized via reversible addition-fragmentation transfer (RAFT) emulsifier-free emulsion polymerization. The spontaneous batch feeding approach was used to control the gradient chain sequence. Transmission electron microscopy (TEM) analysis revealed that the P(TFEMA-grad-AA) can self-assemble to form spherical micelles, rodlike micelles or vesicles in selective solvents. Morphological transition of the P(TFEMA-grad-AA) micelles was sensitive to the water content of the dioxane/water mixed solvent. More interestingly, Ag nanoparticles (NPs) were encapsulated by the P(TFEMA-grad-AA) micelles during the self-assembly process. The gradient chain sequence made the Ag NPs easily enter the core of the micelles, even when P(TFEMA-grad-AA) had less hydrophobic fluoro-units and more hydrophilic units. TEM images with energy dispersive spectrometer indicated that the nanocomposite micelles consisted of a Ag NPs core and a gradient copolymer shell.

Organic polymer materials were used as a layer of adhesive into the graphene sheet between the layers to enhance the interaction force between the nano-structure to achieve excellent mechanical properties and barrier properties. PLA with good flowability and easy processing was selected. The mechanical properties and barrier properties of the graphene-based composites were improved by the use of PLA for good flowability, making it easy to enter the GO layer as a binder. Three methods of preparation of GO / PLA homogeneous composite membranes were designed by vacuum filtration. The experimental results show that the injection of PLA as a molecular binder into the GO layer can effectively mimic the nano-structure, and enhance the intergranular force of the graphene molecules and the compatibility with the polymer matrix.

To take advantage of the polymer’s special properties, we synthesized PVDAT coated polystyrene (PVDAT@PS) microspheres through semi-continuous precipitation polymerization, and demonstrated the possibility of controlling the size of microspheres by using different sized PS cores. Mechanism of the microsphere synthesis was investigated. Preliminary application studies indicated that the synthesized microspheres adsorbed double-stranded DNAs (dsDNAs) comprising A-T base pairs in pH7.4 phosphate buffered saline, and the adsorption capacity was in a range of 3.28mg to 5.58mg per gram PVDAT@ PS microspheres depending on A-T base pair percentage and chain length of the dsDNAs.

Amphiphilic CS-SA polymers were prepared using the SA modified by small molecule water-soluble chitosan, and CS-SA nanomicelles and FF/CS -SA nanomicelles were prepared by using CSSA polymers as the material with dialysis-ultrasound method. CS-SA polymers, CS-SA nanomicelles, and FF/CS-SA nanomicelles were characterized by FT-IR, TGA, and SEM. Results showed that the SA was grafted to the amino of CS by amide bond. CS-SA nanomicelles and FF/CS-SA nanomicelles were spherical, smooth without fold. The influence of different molar ratio of FF to CS-SA polymers on the encapsulation efficiency and drug-loading rate determined the best molar ratio that was 1:1.09. In vitro release experiments, drug release performance study found that hydrophobic drug releasing from FF/CS-SA nanomicelles presented sustained-release. In vitro bacteriostasis experiments, when the concentration was higher than 4.98 mg/mL, FF/CS-SA nanomicelles had antibacterial action and a positive correlation with concentration. The results revealed that amphiphilic chitosan derivative nanomicelles were carriers with broad prospects, increasing solubility of hydrophobic drugs and presenting sustained release for hydrophobic drugs, which provided a new research idea for drug delivery and targeted drug delivery of hydrohobic drugs.