The novel sulfonated polyimide membranes were successfully synthesized by thermal imidization with monomers of 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 4,4′-diaminodiphenyl ether-2,2′-disulfonic acid (SODA) and 3,3′-diaminochalcone (3DAC). Photosensitive chalcone moiety was introduced to the main chain of copolymers, and the photocrosslinking of resulting copolymer in aqueous electrolyte was attempted. A series of sulfonated copolyimide precursors containing chalcone functional groups in the main chain were prepared with different sulfonation degrees by controlling the molar ratio of SODA, 6FDA and 3DAC. The polymer membranes were prepared from these sulfonated aromatic precursors by solution casting and subsequent thermal imidization. The crosslinking with UV irradiation was attempted in the presence or absence of distilled water. The characterizations of the resulting membrane such as the ion-exchange capacity, water absorption and ionic conductivity were performed with respect to the copolymer compositions and the photocrosslinking conditions.

The Fe-based amorphous coatings were produced by air plasma spraying. The as-sprayed coatings were heat-treated at the temperature of 573, 873, and 1 023 K, respectively. The crystallization and wear behavior of the heat-treated amorphous coatings were investigated. It was found that the amorphous-nanocrystalline transformation appeared when the as-sprayed coatings were treated at 853 K. The crystallization process had completed and a coating with microcrystallines was formed when the treatment temperature reached 1 023 K. The resultant amorphous and nanocrystalline composite coatings exhibited superior wear resistance compared to crystalline coating. It is attributed to fine grain strengthening of formed nanocrystallines.

We studied the influence of antimony on the modification rate of the silicon eutectic with sodium and/or strontium for casting of Al-Si alloys, and introduced controlled Ca and Sb to the system and studied the resulting compounds, which were determined to be Ca₂Sb and AlSb. Scanning electron microscopy together with the complementary technique of electron backscatter diffraction (EBSD) were used to characterize the materials. The experimental results provided the basis for us to establish that antimony removal from Al occurs mainly through the reaction (Sb)Al + 2Ca = Ca₂Sb + Al.

The modification of activated carbon with persimmon tannin and its application for the removal of Pb(II) ions were carried out by batch method. The effects of solution pH, contact time, temperature and initial concentration on the immobilization of persimmon tannin were studied. The experimental results showed that the experimental data of persimmon tannin and Pb(II) fitted better by Langmuir adsorption isotherm model and pseudo-second order model. The adsorption capacities of adsorbents for persimmon tannin and Pb(II) were calculated from the Langmuir isotherm model, and found to be 42.97 and 12.40 mg/g at optimum pH, respectively. It was noted that the adsorbent exhibited the best adsorption property for Pb(II) when 1.0 g activated carbon was modified by 17.32 mg persimmon tannin. The modified activated carbon is more effective than the plain activated carbon, and it is expected to be an economic and effective adsorbent for the disposal of wastewater containing Pb(II) ions.

Micro- and nano-sized SiC/fluoroelastomer (FKM) composites were prepared by a mechanical mixing method. These composites were first characterized by a rotorless rheometer. Then the effects of micro- and nano-sized SiC on hardness, static and dynamic mechanical properties of the composites were investigated. The increasing amount of the SiC filler increased the curing efficiency of the biphenyl curing system, which was evident from the rheometric properties of the resulting composites. The tensile properties of composite increased with the increasing of micro- and nano-sized SiC content. When the micro- and nano-sized SiC content was higher than 20 phr, the composites showed almost unchanged tensile properties. The increasing of the tensile property was mainly attributed to the well dispersed micro- and nano-sized SiC particles characterized by SEM images. Compared to pure FKM, the composites exhibited a higher glass transition temperature and lower tan δ peak value.

The magnetic field response results on a five-layer structure given as Metglas /Terfenol-D/Pb(Zr,Ti)O₃/Terfenol-D/Metglas were reported. Due to its high permeability, Metglas can be incorporated as the third phase into conventional Pb(Zr,Ti)O₃/Terfenol-D laminates, which results in a stronger magnetoelectric(ME) response. The increase in Metglas thickness significantly influences the ME response as well. The ME voltage coefficient for a structure with a 150 μm thick Metglas layer on both sides of Terfenol-D/Pb(Zr,Ti)O₃ laminates at 1 kHz was found to be 1.2 V/cmOe at dc magnetic bias field of 590 Oe under an ac magnetic drive of 1 Oe, which was notably higher in comparison to similar structures with other different Metglas thickness.

Magnetic Fe-containing ordered mesoporous carbons (Fe/OMCs) with high surface areas and pore volume were synthesized through a simple soft-template route, wherein phenolic resin was used as a carbon precursor, triblock copolymer F127 as a template agent, tetraethyl orthosilicate (TEOS) as a silica precursor and hydrated iron nitrate as an iron source. The effects of carbonization temperature, loading degree of TEOS on the structural parameters of these Fe/OMCs were evaluated by X-ray diffraction (XRD) and N₂ sorption analysis. The ordering, the specific surface area and the total pore volumes increased with the increase of carbonization temperature from 600 to 850 °C. And the specific surface area and the total pore volumes increased with the increase of TEOS loading.

A series of silica nanoscale materials(NIMs) were prepared through a facile acid-base neutralization. These silica derivatives consist of a nanosilica core, a charged corana(sulfonic acid SIT) attatched to the core, and an oppositely charged canopy (PEG-substituted tertiary amines) to balance the corona. By selecting proper canopy such as surface-functionalized, silica can behave viscous liquid in the absence of any solvent at room temperature. DSC results indicated the melting temperature and glass transition of the derivatives were slightly lower than those of the neat polymer canopy, indicating strong interaction between the core and PEG-substituted tertiary amine.

In order to investigate the phonon scattering mechanisms in double-filled skutterudites, the low-temperature lattice thermal conductivities of In_0.1Yb _yCo₄Sb₁₂ were measured and analyzed based on the Debye model. The eingenmode frequencies of In and Yb were obtained from low-temperature specific heat capacity analysis. It is found that filling these two types of guest atoms with different eingenmode frequencies into the voids in skutterudites could introduce strong point defect and resonant scattering to lattice phonons, thus lead to significant decrease in the lattice thermal conductivity.

62^# and 56^# paraffin mixtures were impregnated into expanded perlite (EP) by vacuuming method. Effects of impregnation with/without vacuum, vacuuming time, and thermal cycles were discussed. The appropriate mass fraction of paraffin mixture in the composite and vacuuming time were found respectively to be 80% and 20 min. Fourier transform infrared spectrometer (FT-IR) analysis shows that it has a good compatibility between paraffin mixture and EP. From differential scanning calorimetry (DSC) analysis, the latent heat of EP/Paraffin mixture composite is almost linearly related with the mass fraction of paraffin mixture in the composite. After 100 thermal cycles, the deviation of phase change temperatures is acceptable, but more deviation of latent heat appears. The calcium stearate dispersing granule coated by epoxy resin can effectively lower leakage during thermal cycles.

Carbon fiber-reinforced silicon carbonitride ceramic matrix composites (C/SiCN) were prepared by rapid electro-thermal pyrolysis CVD using liquid polymer hexamethyldisilazane (HMDS, (CH₃)₃SiNHSi(CH₃)₃) as precursor. Microstructure morphology and production technique of C/SiCN composites were investigated. Scanning electron microscopy and transmission electron microscopy were respectively employed to characterize microstructures of the as-received C/SiCN composites samples. The high temperature pyrolysis of HMDS results in destruction of molecular chain, fracture of bonds, as well as liquid-gas-solid conversion from polymer to ceramic. Microstructures observation indicates that there is a high degree of coalescence between SiCN matrix and C fiber. The deposition model of liquid precursor electro-thermal pyrolysis CVD is different from that of gas precursor isothermal chemical vapor infiltration. Rapid liquid flow and slow gas diffusion are key factors for the difference of two methods. Preparation of rapid electro-thermal pyrolysis CVD consists of four steps including liquid polymer infiltration, polymer pyrolysis, rapid deposition of pyrolyzed substances and rapid densification, respectively.

A novel particle-size conveying model was established to examine the effects of the dimension relationships of the groove depth and particle size on the solids conveying mechanism of the helically grooved feed section. In the model, one or two shear interfaces were proposed based on the dimension relationships of the groove depth and particle size, and the solid-plug embedded in the groove and screw channel were divided into two or three layers by the shear interfaces to consider the solids conveying mechanism of each layer by the boundary condition equation for positive conveying. By the particle-size model, the effects of different dimension relationships on the transformation of solids conveying mechanisms between the friction-drag conveying and the positive conveying were discussed and compared with the on-line measuring experimental data. The results showed that the shear interfaces among the solids existed indeed and the dimension relationships determined the conveying mechanism and the throughput of helically grooved extruders, which was well confirmed by the excellent consistence between the predicted and measured data.

According to the principle of grain refining and slurry preparation by cooling sloping plate process, the distributions of boundary layers during melt treatment by cooling sloping plate were studied, and mathematic model of cooling rate was established. The calculation value approximately agrees with the experimental result. Laminar flow and turbulent flow exist on sloping plate surface commonly. The thickness of velocity boundary layer and the critical transfer distance from laminar flow to turbulent flow increase with the decrease of initial flow velocity. The thickness of temperature boundary layer increases with the increment of flow distance and the decrease of initial flow velocity. The melt cooling rate and melt thickness have an inverse proportion relationship. The melt cooling rate increases along the plate direction gradually when the initial flow velocity is lower than 1 m/s, the melt cooling rate keeps nearly a constant when the initial flow velocity is 1 m/s, when the initial flow velocity is higher than 1 m/s, the melt cooling rate decreases gradually. The melt cooling rate of cooling sloping plate process can reach 10²–10³ K/s and belongs to meta-rapid solidification scope.

To study the effects of different proportions of aluminum hydroxide and expandable graphite (EG) composites on flame retardation, sealing, mechanical, electrical and other properties of RTV-1, aluminum hydroxide/expandable graphite (ATH/EG) and silicone rubber composites were prepared by the compression molding method. The experimental results show that heat resistance improves with the increase of proportion of EG. Although the resistance coefficient changes, the composite materials still keep good electrical insulating property. Moreover, oxygen index and expansion index rise first then fall. When ATH/EG is 1:1, the oxygen index reaches the highest; the mechanical property of the silicone rubber is not affected under various environments such as acid, alkali, oily, artificial sea water environments, etc.

To study the internal damage of concrete under freeze-thaw cycles, concrete strains were measured using embedded strain gauges. Residual strain and coefficients of freezing expansion (CFE) derived from strain-temperature curves were used to quantify the damage degree. The experimental results show that irreversible residual strain increases with the number of freeze-thaw cycles. After 50 cycles, residual strains of C20 and C35 concretes are 320μɛ and 100μɛ in water, and 120 μɛ and 60 μɛ in saline solution, respectively. In lower temperature range (−10 °C to −25 °C) CFE of C20 and C35 concretes decrease by 9.82×10⁻⁶/K and 8.44×10⁻⁶/K in water, and 9.38×10⁻⁶/K and 5.47∼10⁻⁶/K in saline solution, respectively. Both residual strains and CFEs indicate that during the first 50 freeze-thaw cycles, the internal damage of concrete in saline solution is less than that of concrete in water. Thus residual strain and CFE can be used to measure the frost damage of concrete.

The effect of two different curing regimes on the polymerization degree of C-S-H in hardened cement pastes within 28 d were investigated by measuring the chemical environments of ²⁹Si with magic angle spinning (MAS) nuclear magnetic resonance (NMR) and by analyzing the ²⁹Si NMR spectra with deconvolution technique. The experimental results indicate that, at curing regime of constant temperature of 20 °C, the polymerization of C-S-H increases and then decreases with curing age, and the Al/Si ratio increases gradually with curing age, furthermore, the two non-bridging oxygen bonds of bridging silicate tetrahedra in C-S-H structure mainly bond to H⁺. At curing regime of variable temperature, the polymerization of C-S-H firstly increases then changes slightly and subsequently decreases with the temperature from low to high and then to low, and the Al/Si ratio firstly increases then keeps invariant and subsequently slightly decreases. Moreover, the temperature decreasing is advantageous for the Ca²⁺ to be bonded to the bridging silicate tetrahedra and entering into the interlayer of C-S-H structure. The polymerization of C-S-H at curing regime of variable temperature is higher than that cured at constant temperature, but the curing regime of constant temperature is more beneficial to the substitution of Al³ for Si⁴⁺ than that of variable temperature.

The main reaction products were investigated by analysis of microstructure of alkali-activated ground granulated blast furnace slag (GGBFS) paste. An experimental research was performed on bond performance of alkali-activated GGBFS paste as a construction adhesive after exposure to 20–500 °C. Through XRD analysis, a few calcium silicate hydrate, hydrotalcite and tetracalcium aluminate hydrate were determined as end products, and they were filled and packed each other at room temperature. In addition, akermanite dramatically increased at 800 °C and above. The two key parameters, the ultimate load P _u.T and effective bond length L _e, were determined using test data of carbon fiber-reinforced polymer (CFRP)-to-concrete bonded joints at elevated temperature. The experimental results indicate that the ultimate load P _u.T remains relatively stable initially and then decreases with increasing temperature. The effective bond length L _e increases with increasing temperature except at 300 °C. The proposed temperature-dependent effective bond length formula is shown to closely represent the test data.

CRMA was prepared by mixing PG 64-22 asphalt with crumb rubber powder of 40 mesh size and 18% by weight of the asphalt. Sasobit®, a typical organic wax additive, was selected and added into CRMA. A series of tests, namely, brookfield viscosity, environmental scanning electron microscope(ESEM), component test, differential scanning calorimeter(DSC), fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) were conducted on CRMA with and without organic wax additive, and microcosmic appearance, component content and molecular structure of various asphalt binders were obtained. The test results indicate that the addition of Sasobit® into CRMA can effectively change the contents of components: the content of asphaltenes increases relatively, while saturates decreases. In addition, the interaction between various components of CRMA is weakened, and the state of equilibrium between the dispersant and dispersed phase is changed at the same time. That is why the viscosity decreases after the organic wax additive is added into CRMA.

The effects of specimen size and shape on development of water loss and shrinkage of mortar and concrete respectively were investigated. The experimental results showed that the effects of specimen size and shape on water loss ratio were consistent with those on drying shrinkage strain. It is also indicated that drying shrinkage strain has obvious linear correlation with water loss ratios independent of specimen size and shape. The effects of specimen size and shape on the water loss ratio were embodied in established model of averaged relative humidity improved by considering effects of sequential hydration and calculated by finite difference method. Furthermore, the effects of specimen size and shape on drying shrinkage strain of concrete were experimentally deduced and applied to modify criterion EB-FIP1990. The comparison between experimental and calculated results shows that the modified EB-FIP1990 can be adopted to predict drying shrinkage strain of concrete with reasonable accuracy.

A novel calcium phosphate cement was developed by adding different amount of SrO to tetracalcium phosphate during the fabrication process. The experimental results show that compressive strength of cements based on tetracalcium phosphate doped with SrO significantly increases with the increase of SrO content, approximately 60 MPa, whilst the mechanical behavior of CPC slightly decreases if 0.7wt% SrO is added. X-ray diffraction measurement confirms the setting reaction of doped cements is similar to that of pure calcium phosphate cement (CPC). Low crystalline hydroxyapatite (HA) is found to be the main constituent of set cement. A mechanical reinforcement effect is resulted from the substitution of Sr ion to Ca²⁺ in tetracalcium phosphate (TTCP), accelerating HA crystal formation and a more cross-linked cement structure. In vitro bioactivity tests showed that CPC added with 0.5wt% SrO had a more rapid degradation compared with pure CPC.

To explore the mechanisms of filter mud (FM) in the portland cement clinker formation, and to make effective use of FM in the cement production as lime-based raw materials, the influences of FM on the apparent activation energy of calcium carbonate decomposition, liquid phase amount, crystalline phase and tricalcium silicate polymorphism were investigated by TA, SEM and XRD. The experimental results show that FM can reduce apparent activation energy of calcium carbonate decomposition, and increase liquid phase amount. Appropriate FM replacement ratios are useful to promoting the C₃S formation and heightening the C₃S content. New phases of α-C₂S and C₂S·0.5Ca₃ (PO₄)₂ can be found in the clinkers while the ratios are above 15%. In addition, impurities in FM can induce the C₃S polymorph to transform.

This paper focused on the evolution over time of elasticity of the cement paste during the hydration, e g, Young’s modulus and Poisson’s ration, by the proposed homogenization method combined the percolation algorithm with individual phase intrinsic elasticity. A cement paste development model, named CEMHYD3D, was used to establish an accurate microstructure. The modelling results are in good agreement with the experimental data and other numerical results available in the open literature. The suitable homogeneous scheme, applied to each level, should be carefully chosen to result in a realistic prediction. The percolation concept should aims to correctly predict the elasticity for cement paste at very early age, especially under low w/c ratios.

The compressive strength and flexural strength with the same strength class cement mortar of the alkali-resistant glass fiber cement mortar were tested in standard and hot-water curing condition, and the damage mechanism of alkali-resistant glass fiber was studied. The interaction mechanisms of the chemical erosion and physical injury in different curing conditions were studied in order to summarize the damage mechanism of alkali-resistant glass fiber in cement-based materials, and chloride diffusivity coefficient and porosity of cement mortar were tested in the different curing conditions. The experimental results are that the strength of cement based materials and fiber cement slurry interface zone were closely related, and heat curing could accelerate the hydration of cement, but inevitably enlarge the defect.

Poly(N-isopropylacrylamide-co-N-vinylpyrrolidone) [P(NIPAM-co-NVP)] copolymers with different content of N-vinylpyrrolidone (NVP) were synthesized, and reversible aggregation kinetics of the copolymers in aqueous solutions was investigated with elastic light scattering (ELS) spectra. The results indicated that the apparent activation energy of aggregation process during heating and dissociation process during cooling increased with the NVP content increasing. The phase transition temperature also increased as the content of NVP increased, suggesting that the hydrophilic nature of NVP strongly affected the phase behavior of the copolymer solutions. The higher the content of NVP, the higher the temperature required to break the balance between the hydrophilic and hydrophobic interaction. Besides, during heating and cooling process, the phase transition hysteresis of P(NIPAM-co-NVP) chains decreased when the hydrophilic comonomer increased.

New composites of waterborne polyurethane (WPU) as a matrix were prepared by incorporating rigid supramolecular nanoplatelets (SNs) as filler, which were self-assembled by the selective inclusion of β-cyclodextrin (β-CD) onto poly(propylene oxide) (PPO) segment in the poly(ethylene oxide)-block-PPO-block-poly(ethylene oxide) (PEO-b-PPO-b-PEO). It is worth noting that, when the loading level of SN is lower than 3wt%, the SNs with moderate PEO length result in the simultaneous increase in strength, elongation and Young’s modulus in contrast with neat WPU. If there is no stretching free PEO chain, both strength and elongation decrease in spite of an increase in Young’s modulus. However, too long PEO chains result in the decrease of mechanical performances while the relatively higher loading-level of SNs also inhibits the enhancement of strength and elongation.

A kind of chemical method that used water as the liquid reaction medium to decompose epoxy resin was studied. The thermosetting epoxy resin was decomposed successfully under the condition of near-critical water. The decomposition rate of epoxy resin raised rapidly as the reaction time and reaction temperature increased. The decomposition reaction products were characterized by infra-red spectra and gas chromatography-mass spectrometry. The phenol, isopropylphenol, 4, 4′-(1-methylethylidene) bis-phenol were found as the main compounds in liquid products, which were common monomers from epoxy resin. When reaction was carried out at the temperature of 260 °C–300 °C, the decomposition mechanism of epoxy resin was envisaged as the ether and ester bonds cracking.

The photocatalytic properties of polypyrrole nanoparticles prepared by W/O microemulsion method were reported. During the photodegradation of Orange II and Methyl Orange as organic dyes in UV/H₂O₂ and UV irradiation systems using polypyrrole nanoparticles as photocatalyst, the latter performances special photocatalytic activity towards to above dyes in both UV and UV/H₂O₂ system. In detail, its photocatalytic activity is 5.17 and 4.82 times higher than normal polypyrrole composites in UV/Orange II and UV/MO system relatively. The size of polypyrrole nanoparticles characterized by TEM is 200–400 nm with good dispersity. The further measurement by accelerated surface area and porosimetry system shows such nanoparticles have a specific surface area of 1.47 m²/g compared to normal polypyrrole of 0.22 m²/g. This conjugated polymer characterized by FTIR spectroscopies before and after photocatalytic reactions shows reliable chemical stability. In addition, it holds excellent recovery ability and keeps up their catalytic activity within distinctive drop after six repeated utilization.

The in vitro degradation rate of polyanhydride (poly(sebacic acid), diacetoxy terminated), also known as PSADT, was investigated. PSADT tablets with a circular cross-section were formed using a compression molding device, and then immersed into phosphate buffer saline (PBS) for in vitro degradation experiments. The mechanisms of degradation and the degradation rate were characterized by the change in molecular weight and reduction in specimen mass. In addition, the effects of processing temperature and the geometry of the formed PSADT tablets on the rate of degradation were studied. The surface morphology at different degradation times was observed by scanning electron microscopy (SEM). The experimental results showed that PSADT exhibited surface erosion due to the fact that near zero-order degradation kinetics was observed during its degradation process. Moreover, it is found that the geometry of tablets played an important role on the rate of degradation, while the processing temperature had no significant effect on the PSADT degradation rate.

The rheological behavior, thermal properties and foam morphology of linear polypropylene and long chain branching polypropylene prepared through UV irradiation reactive extrusion were studied by rheological test, melt index test, DSC and supercritical carbon dioxide foaming technology. Rheological test and melt index test confirmed that under UV irradiation and extrusion, adding photo-initiator and crosslinking agent could achieve the purpose of branching, thus improved the melt strength of polypropylene effectively. The DSC results revealed that with the introducing of long chain branching, the melting range of the polypropylene broadened and the crystallization temperature increased. Owing to the introduction of long chain branches, polypropylene exhibited higher melt strength and strain hardening behavior. Compared with linear polypropylene, the foam morphologies of long chain branching polypropylene were more uniform.

Both of quaternary ammonium and quaternary phosphonium salts of bis-hydroxyethyl terephthalate (BHET) were successfully synthesized and characterized by fourier transform infrared spectroscopy (FT-IR). These two kinds of salts were used to intercalate Na-MMT to yield two kinds of respective organo-modified MMTs. Basal spacing and thermal stability were investigated by using X-ray diffraction (XRD) and thermogravimetric analysis (TGA), respectively. The experimental results show that, as compared with Na-MMT, basal spacings of both of MMTs modified by the quaternary phosphonium salt of BHET (BHETPP) and the quaternary ammonium salt of BHET (BHEA), increase from 12.4 Å to 19.7 Å and 31.3 Å, respec-tively. Thermal stability of BHETPP-modified MMT is much better than that of BHEA-modified MMT, i e, T _onset of BHETPP-modified MMT is around 400 °C while T _onset of BHEA-modified MMT is near 250 °C. Therefore, with en-larged basal spacing and excellent thermal stability, BHETPP-modified MMT is a promising organo-modified MMT which may be used to prepare polyethylene terephthalate/MMT nanocomposite with high thermal and mechanical performance.

The influences of chromium-free chemical conversion treatment and anodizing treatment on bonding strength of AZ31 magnesium alloy were studied by lap-shear test, SEM and electrochemical methods. Both chemical conversion treatment and anodizing can increase the bonding strength. The anodizing treatment gives higher bonding strength and better corrosion resistance than chemical conversion treatment. The increase of bonding strength by the treatments may be attributed to the uneven surface structures with micro-pores, resulting in increased bonding areas and the embedding effect.

The structure and mechanical properties of a new type of Al-based discontinuous gradient composites prepared by using the ternary Al-19Si-5Mg alloys as the raw material adopting the centrifugal casting method were investigated. Structurally, the composites are divided into two zones: a reinforced zone with the high volume fraction of primary Si and Mg₂Si particles and an unreinforced zone with no or a few particles. In the reinforced zone, the primary particles are evenly distributed, with the sizes of the primary Si particles 80–120 μm, and that of primary Mg₂Si particles 20–50 μm. The properties test results show the reinforced zone has higher Rockwell hardness and better wear resistance than the unreinforced zone, due to the complementary reinforcement relationship between the primary Si and Mg₂Si particles and their high volume fraction.

The flow stress behavior of SCM435 steel was studied by using a MMS-200 thermal simulation machine, under the conditions with deformation temperatures of 1023–1323 K and strain rate of 0.01–10 s⁻¹. The experimental results indicated that the critical strain would get smaller with the increment in temperature and the decrement in strain rate, leaving the dynamic recrystallization easier to occur. The peak stress constitutive equation of SCM435 steel under high temperatures was established by the form of hyperbolic sine, and the activation energy of deformation under high temperature was obtained by regression equation. The critical strain ɛ _c for dynamic recrystallization was accurately derived from the θ-σ curve containing strain hardening rate θ and flow stress σ. Then the correlation between peak stress, peak strain, critical stress, critical strain and the parameter Z was further obtained. The Avrami kinetic equation of dynamic recrystallization for SCM435 steel was developed from stress-strain curve, and the Avrami exponent m was abstracted. Observations also indicated that the Avrami constants would decrease with increments in temperature, but increase with increments in strain rate. The Avrami constant took small influence from the deforming temperature, but significant influence from strain rate, and the correlation between Avrami constant and the strain rate was obtained by regression equation.

By using double glow plasma surface metallurgy technique, the molybdenum (Mo) surface-modified layer on titanium (Ti) was obtained. The corresponding cross-section morphology, phase formation, and element concentration were investigated by optical microscopy, X-ray diffraction (XRD), and glow discharge optical emission spectroscopy (GDOES), respectively. The experimental results indicate that the Mo modified layer is composed of a 1.7 μm pure Mo deposition layer and a 14.3 μm Mo diffusion layer. Along the sample thickness direction, nanoindentation tests were performed on the cross-section of the Mo diffusion layer and the Ti substrate (for the comparison purpose) by Hysitron TI900 TriboIndenter. The 2D and 3D residual indentation profiles of the Mo diffusion layer were obtained by scanning probe microscopy (SPM). The elastic modulus and hardness values of every indent were acquired and analyzed. According to the load-displacement curves, the plastic deformation degrees of the Mo diffusion layer and the Ti substrate were analyzed. It is indicated that the Mo diffusion layer possesses high strength-toughness.

A direct electroless copper (Cu) coating on tungsten powders method requiring no surface treatment or stabilizing agent and using glyoxylic acid (C₂H₂O₃) as a reducing agent was reported. The effects of copper sulfate concentration and the pH of the plating solution on the properties of the prepared W@Cu composite powders were assessed. The content of Cu in the composite powders was controlled by adjusting the concentration of copper sulfate in the electroless plating solution. A uniform, dense, and consistent Cu coating was obtained under the established optimum conditions (flow rate of C₂H₂O₃ = 5.01 mL/min, solution pH = 12.25 and reaction temperature 45.35 °C) by using central composite design method. In addition, the crystalline Cu coating was evenly dispersed within the W@Cu composite powders and Cu element in the coating existed as Cu0. The formation mechanism for the W@Cu composite powders by electroless plating in the absence of surface treatment and stabilizing agent was also proposed.

The effects of the solution and aging treatment on microstructures and mechanical properties of the Mg-10Zn-5Al-0.1Sb-XCu cast magnesium alloys were investigated by brinell hardness measurement, scanning electron microscopy (SEM), energy spectrum analyzing apparatus and X-ray diffraction (XRD). The experimental results show that the strip-like τ-Mg₃₂ (Al, Zn)₄₉ phase is shown at the grain boundaries and Mg₂Cu phase become smaller, even granular after solution treatment at 350 °C for 24 h. By ageing treatment at 180 °C, the ternary strengthening phase (τ phase) precipitates gradually at or around grain boundary. With increasing aging time, the micro-hardness improves obviously and up to the maximum (105.9 HV) at aging time of 36 h. In addition, the tensile-strengths at room temperature and at an elevated temperature respectively reach 228 MPa and 176 MPa, which is increased by 20% and 10%, respectively.

The effects of Dy on the microstructure and magnetic properties of Dy _xCo_50−xPt₅₀ alloys were investigated. The XRD results indicate that all the alloys homogenized at 1000 °C contain only a single A1 (fcc) phase, while the alloys annealed at 675 °C consist of a hard-magnetic face-centered-tetragonal (fct) phase and a magnetically soft face-centered-cube (fcc) phase. Maximum values for the coercivity H _c and remanence ratio m _r were achieved in Dy_0.4Co_49.6Pt₅₀ alloys annealed at 675 °C for 80 min. For the series of Dy _xCo_50−xPt₅₀ alloys annealed at 675 °C for 60 min, H _c decreases monotonically with increasing Dy concentration, but m _r is first enhanced and then weakened.

The long-term aging behavior of an alumina-toughened zirconia (ATZ) ceramic in artificial saliva hydrothermal atmosphere was determined and compared with that of tetragonal zirconia polycrystals doped with 3mol% Y₂O₃ (3Y-TZP). The specimens of 3Y-TZP and ATZ were aged in distilled water and artificial salivary respectively at 134 °C. Monoclinic phase content was evaluated by X-ray diffraction (XRD) analysis. Specimen strength was determined by a biaxial bending test. Surface screening was done using an atomic force microscope (AFM). No statistically significant influence of any treatment on strength was demonstrated for either material. However, XRD measurements revealed ATZ’s anti-aging properties were much better than TZP after the aging treatment. Therefore, ATZ can be applied to the field of dentistry. Artificial saliva in ceramic surface sediments may be useful for strengthening ceramics.

The purpose of this study was to evaluate the long time antibacterial properties and shear bond strength of experimental nano silver-containing cements (NSC). Nano silver base inorganic antibacterial powder was added to the reinforced glass ionomer cement at five different weight ratios to obtain a series of nano silver-containing cements, then the antibacterial properties of three orthodontic cement products and five NSC samples were evaluated by the direct contact test (DCT) and the agar diffusion test (ADT). The DCT, which was based on turbidness determination of bacterial growth in 96-well microtiter plates, was performed in both fresh and aged for 1 day, 1 week, 2 weeks, 3 weeks, 4 weeks, 6 weeks, and 8 weeks tested materials. The shear bond strengthes of three orthodontic cement products and five NSC samples were examined using a universal testing machine. The ADT results indicated that there were no significant differences between NSCs and ORTHO LC fresh specimens. In the DCT experiment, all fresh silver nanoparticles-containing tested samples presented powerful antibacterial properties, but they gradually lost the effective antimicrobial agents with the extension of aging time. Finally, none of the tested materials maintained its antibacterial property after aging for 8 weeks. A gradually decreasing trend of bond strength presented with the increasing incorporation of nano silver base inorganic antibacterial powder into the glass ionomer cement, even though all the tested material specimens reached the ideal bond strength range. We may conclude that NSCs can contribute to decrease the demineralization rate around brackets without compromising bond strength.