Graphene/manganese dioxide composites and grapheme /manganese dioxide/sulfur (G/MnO₂/ S) composite cathode were prepared by hydrothermal method and by vapor permeation, respectively. Their structure, morphology and specific surface area were characterized by X-ray diffraction, electron microanalysis and nitrogen adsorption analysis. The composites show morphology of nanosheets, high specific surface area and even distribution of sulfur. The sulfur accounts for 75% in the G/ MnO₂/S composite by thermogravimetric analysis. The electrochemical performance of G/S and G/ MnO₂/S cathode were investigated. The G/ MnO₂/ S composite cathodes show excellent rate performance and cycle stability. At a 0.2C current density, initial discharge specific capacity is 1 061 mA·h·g⁻¹ and maintains 698 mA·h·g⁻¹ after 100 cycles; At a 1C current density, maximum discharge capacity reaches 816 mA·h·g⁻¹ and average capacity decreasing rate is only 0.073%/ cycle after running over 400 cycles. Electrochemical mechanism of the composites cathodes was analyzed. The sulfur adsorption of MnO₂ inhibited the loss of active material sulfur, so, the electrochemical performance of the complex was improved.

The effect of graphite surface modification on the thermal conductivity (TC) and bending strength of graphite flakes /Al composites (Gf/Al) prepared by gas pressure infiltration were investigated. Al₃Ni and Al₄C₃ phase may form at the interface in Ni-coated G _f/Al and uncoated G _f/Al composites, respectively, while the Al-Cu compound cannot be observed in Cu-coated Gf/Al composites. The Cu and Ni coatings enhance TC and the bending strength of the composites in the meantime. TC of Cu-coated G _f/Al composites reach 515 Wm⁻¹·K⁻¹ with 75 vol% G _f, which are higher than that of Ni-coated G _f/Al. Meanwhile, due to Al₃Ni at the interface, the bending strength of Ni-coated G _f/Al composites are far more than those of the uncoated and Cu-coated G _f/Al with the same content of Gf. The results indicate that metal-coated Gf can effectively improve the interfacial bonding between G _f and Al.

Mullite and corundum co-bonded SiC-based composite ceramics (SiC-mullite-Al₂O₃) were prepared by using SiC, calcined bauxite and kaolin via pressureless carbon-buried sintering. The low-cost SiCbased composite ceramics designed in this study are expected to be used as thermal storage materials in solar thermal power generation based on the high density and excellent thermal shock resistance. The influences of calcined bauxite addition and sintering temperature on the microstructures, phase compositions, and physical properties of the samples were investigated. Results demonstrated that the introduction of calcined bauxite containing two bonding phases greatly reduced the lowest sintering temperature to 1 400 °C. The SiC-mullite- Al₂O₃ composite with 40 wt% calcined bauxite sintered at 1 500 °C exhibited optimum performance. The density and bending strength were 2.27 g·cm⁻³ and 77.05 MPa. The bending strength increased by 24.58% and no cracks were observed after 30 thermal shock cycles, while general clay would reduce the thermal shock resistance of SiC. The SiC-mullite-Al₂O₃ composites with satisfied performance are expected to be used as thermal storage materials in solar thermal power generation systems.

Influence of structural variations of N-vinylimidazolium tetrahalogenidoferrate (III) magnetic ionic liquids (MILs) on thermal properties was investigated. Using Gaussian09/B3PW91/6-311G (2d, p) density functional methods, the microstructure of the MILs were analyzed. With differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA), the thermal properties of the MILs were performed. The results showed that the interaction energies of ion pairs decreased, the crystallization temperature increased first and then decreased, and the surfusion first decreased and then increased with the elongation of the alkyl chain length on cation; with the increase of Br atom, the interaction energies of ion pairs increased; the interaction energies of ion pairs increased in the MILs with the same cation or anion, the nature of polarity of MILs increased and the melting point rose; as the cation or anion in MILs had a smaller size, it could have the solidsolid transition temperature. The results indicated that the decomposition temperature with the same type of MILs increased with the interaction energies of ion pairs. The interaction energy of ion pairs can be used to illuminate the correlation between the thermal properties and the structure of MILs. ILs possesses the properties of macromolecular.

Three different kinds of sepiolite (Type A, Type B and Sepiolite fiber) were processed by calcination and analyzed by thermogravimetric analysis (TG), X-ray diffraction diffractometer (XRD), scanning electron microscopy (SEM), BET (specific surface area from N2 adsorption isotherms), mercury intrusion porosimetry (MIP), and infrared spectroscopic analysis (IR), respectively. The results show that the adsorption performance of sepiolite can be changed by calcination and environment temperatures, especially for calcination. The adsorption capacity of sepiolite fiber is bigger than that of Type A and B, and adsorption capacity of each sepiolite to sulfate is smaller than that of the chloride ions. Especially, the maximum value for adsorption of the sepiolite fibers, calcined at 600 ℃ and water bath at 60 ℃, to chlorine ion and sulfate are 5.95 and 5.71 mg/g, respectively (mg/g: the ions quantity adsorbed by a unit of sepiolite weight). The minimum adsorption of calcined sepiolite fiber to sulfate ions increased from 5.02 to 5.55 mg/g. While microstructure analysis of sepiolite by TG indicated that its structure was, for temperature not exceeding 700 ℃, was not changed significantly. Sepiolite has a porous structure, especially for sepiolite fiber, which can be observed by SEM. BET indicates that sepiolite fiber has a larger pore volume than others and this can be increased by calcination. IR shows that the adsorption of sepiolite to Cl- and SO4 2- belongs to physical absorption, instead of chemisorption.

Rice husk ash/natural rubber composites were fabricated by modifying rice husk ash with the rare earth coupling agent DN-8102. The structure of the rice husk ash and the morphological dispersion of the rice husk ash in a rubber matrix were charactered by scanning and transmission electron microscopy, respectively. The mechanical properties of the composites were experimentally studied. The surface energy and the interaction between rice husk ash particles can be reduced by surface modification of rice husk ash with a rare earth coupling agent, which reduces the agglomeration of rice husk ash in both liquid and rubber matrices and enhances the interactions between rice husk ash and the rubber phase, and thus results in improved mechanical properties for the resulting rice husk ash/natural rubber composite. The modulus of the composites will increase as the loading level of modified rice husk ash increases. A maximum tensile strength of 25.96 MPa for the composites can be obtained when the modified rice husk ash loading level is 4%.

Mechanical systems on all length scales may be subjected to nanoscale thin film lubrication (TFL). Molecular dynamics (MD) simulations were conducted to investigate the lubrication mechanism and boundary slip of squalane confined in nanogap at 293 K with two different film thicknesses and a wide range of pressures. The molecular distribution, density and velocity profiles of squalane were analyzed. The results show that the lubricant atoms tend to form layers parallel to the wall, but the lubricant molecules orient randomly throughout the film in the directions both parallel and perpendicular to the wall. Most squalane molecules appear twisted and folded, and extend to several atomic layers so that there are no slips between lubricant layers. The distances between the lubricant layers are irregular rather than broadening far away from the walls. The boundary slip at the interface of bcc Fe (001) and squalane only occurs at high pressure because of the strong nonbond interactions between lubricant atoms and wall atoms. The tendency of boundary slip is more obvious for films with thinner film thickness. According to the simulations, the relationship between the slip length and the pressure is given.

(ZrMg) _xY_2–2xMo₃O₁₂ (x=0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1) ceramics have been synthesized to obtain less hygroscopicity and negative thermal expansion. With increasing the substitution of (ZrMg)⁶⁺ (ion radius 7.2 ×10^–11 m) for Y³⁺ (ion radius 9×10⁻¹¹ m), the crystal water are reduced obviously. The linear thermal expansion coeffcient is improved with increasing the content of (ZrMg)⁶⁺. The material shows near zero thermal expansion (−0.12×10⁻⁶ K⁻¹, 430–870 K) with x=0.7. Meanwhile, ZrMgMo₃O₁₂ shows low non-hygroscopicity and negative thermal expansion, but low softening temperature. After substituting amount of Y³⁺ for (ZrMg)⁶⁺ in ZrMgMo₃O₁₂ (x=0.8), the softening temperature increases remarkably (750 K to 830 K) and it presents near zero thermal expansion.

To promote the stability and efficiency, quadruple-cation perovskite system (blending of MA, FA, Cs, I, Br, etc) was introduced to substitute the traditional MAPbI₃ perovskite. Perovskite films degraded by water can be recovered by a simple method. The PbI₂ residues decomposed from perovskite were transformed into perovskite again, which gave rise to remarkably boosted optical properties, drastically improved film morphology and largely suppressed pinholes. The efficiency of the repairing method was testified by fieldemission scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and so on. The power conversion efficiency of fixed perovskite solar cells improved from around 3% to 15.78% (0.16 cm₂, mask area), and 12.56% at area of 1 cm₂, which prove that this method is very effective.

Nitrogen doped multi-channel graphite was successfully prepared by using nitrogen doping and KOH etching technologies. The three-electrode and EIS tests indicates that the etched graphite possesses lower electrochemical resistance than the pristine graphite. The coin cell tests demonstrate that N doped multichannel graphite possesses a specific capacity of 361 mAh/g and coulombic efficiencies of 91.4%. No dramatic irreversible capacity loss results from the increased specific surface area (from 1.60 to 2.08 m2/g), removing the need for a trade-off between irreversible capacity loss and surface area. Full polymer cells were fabricated and electrochemical capabilities were measured. In 3C fast charge protocol, the charging capacity can reach 51% within 10 min charge, and 100% within 30 min, demonstrating excellent fast charging characteristic. The fast charge cycle performance with 3C-rate charge and 1C-rate discharge from 4.35-3.0 V was conducted at RT temperature. The capacity retention is 94% after 600 cycles, which shows good cycle performance.

A low-cost and efficient filter medium for Cd(II) removal was prepared by anchoring -SCN functional groups (by 3-thiocyanatopropyltriethoxysilane, TCPS) on ceramsite via the approach of synthesizing a honeycomb calciumaluminum-silicate-hydrate (C-A-S-H) layer as intermediate. The specific surface area of ceramsite was increased enormously by more than 50 times because of the modification of honeycomb layer. Moreover, the abundant Si-OH bonds existing in the structure of CAS-H can serve as active sites for TCPS. The combined effects ensure that the hybrid filter medium (named ceramsite/C-A-S-H/TCPS) demonstrated a high Cd(II) adsorption capacity of 18.27 mg·g¹ for particle size of 0.1-0.6 mm, 12.63 mg·g⁻¹ for 0.6-1.25 mm and 8.64 mg g⁻¹ for 1.25-2.35 mm. The Cd(II) adsorption capacity per unit area of ceramsite/C-A-S-H/TCPS (0.1-0.6 mm) is up to 4.07 mg·m⁻², which is much higher than that of many nano-adsorbents. In addition, ceramsite/C-AS- H/TCPS could maintain a high removal efficiency (> 85%) in a wide range of pH 3-11 and showed excellent selectivity in the presence of competing ions. Furthermore, Cd(II) could be desorbed from ceramsite/C-A-S-H/TCPS composites with nearly 100%, suggesting the potential application in recycling of heavy metal ions.

An adhesive of the SiBCN ceramic was synthesized through the polymer derived ceramics (PDC) route. Meanwhile with higher adhesion strength and simpler process condition, the polyborosilazane (PSNB) was modified by E-44 epoxy resin. The E-44 epoxy resin was used to promote the oxidation process of SiBCN, in other words, to produce more amount of SiO₂-B₂O₃ glasses. The phase composition, elemental analysis, chemical bonds and microstructure were investigated by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM) measurements. The E-44 modified adhesives were cured at 120 °C in air for 2 h, and were pyrolyzed at 1 200, 1 400, and 1 500 °C for 2 h in air, respectively. The highest adhesion strength of the modified adhesive was up to 5.33, 12.23, and 12.50 MPa after being heat treated at 1 200, 1 400, and 1 500 °C, respectively. Finally, we proposed an adhesion model and revealed the adhesion mechanism of SiBCN ceramic.

Nano-ZrO₂ and PEEK particles were synergistically filled in unfilled PTFE to improve the wear resistance and maintain a relatively low friction coefficient, and the materials were studied using a reciprocating sliding friction and wear tester. In the friction tests, the evolution of various tribological characteristics in both the contact interfaces and debris was observed, and the wear mechanism of the PTFE composites was investigated. The results showed that the wear rate of the PTFE composites synergistically filled with nano-ZrO₂ and PEEK was lower and its friction coefficient was slightly higher than that of the unfilled PTFE; the uniformity and continuity of the transfer film generated by the composite with nano-ZrO₂ and PEEK were the best, and the particle size of the debris was minimal in comparison to that in other sample systems.

The CdS/ spherical g-C₃N₄ n-n heterojunction photocatalyst was fabricated via a solvothermal method. The tetracycline was used to characterize the photocatalytic properties of the as-developed hybrids. The photocatalytic degradation mechanism of the as-developed heterojunction photocatalyst was also analyzed. Research results show that CdS nanoparticles are well dispersed in the surface layer of spherical g-C₃N₄. Moreover, the mass ratio of CdS to spherical g-C₃N₄ will influence the photocatalytic activity of the asdeveloped composites, which shows the trend of first increasing and then decreasing as it increased. When the mass ratio is 7:1, in 25 min, the as-developed heterojunction shows 93.2 % of the maximum photocatalytic efficiency and still exhibits 83.6 % after 5 times cycle testing. Moreover, the as-developed hybrids can accelerate the electron transport and improve the separation efficiency of photo-generated carriers compared with pure samples. In addition, the holes and superoxide radicals are dominating active species during the photocatalytic degradation process.

The microstructure and performance of Li₄Ti₅O₁₂ doped by Mg prepared by hydrothermal method and solid phase method were investigated. Lithium dihydrate, magnesium acetate and tetrabutyl titanate were used as the main raw materials. This study reveals that Mg²⁺ has influences on the spherical structure, crystal development of Li₄Ti₅O₁₂ and the electrochemical performances. The hollow spherical structure is composed of nano-sheet structure and the nano-sheet structure can be affected by the Mg²⁺ content. For Li4-xMgxTi₅O₁₂, the sheet structure can be refined with the increment of Mg²⁺ content when x value is 0-0.1 and coarsen with the increment of Mg²⁺ content when x value is 0.1-0.2. The hollow spherical Li₄Ti₅O₁₂ powders prepared by hydrothermal method have better performance. The optimal Mgdoped amount of hydrothermal method is 0.1. At 0.1C, the first discharge capacity of Li3.9Mg0.1Ti₅O₁₂ prepared through hydrothermal method at 0.1C and 10 cycles is 182 and 178 mA h g⁻¹, respectively.

A micro-scale finite element method (FEM) was proposed to precisely calculate the heat conduction between mortar and aggregate, and thus to accurately predict the non-uniformity of concrete pouring temperature. The concrete temperature feld during vibration was also precisely calculated by accurate description of heat absorption characteristics of different parts of concrete when vibration. Based on the above method, the prediction model was used to predict the pouring temperature of a practical engineering. The comparison between actual results and simulated values shows that this method can be adopted to accurately predict the non-uniformity of concrete pouring temperature and the influence of mechanized vibration on concrete pouring temperature, and thus accurately predict pouring temperature. The control of casting temperature is crucial for preventing concrete fracture. The study provides a new method for predicting the pouring temperature of concrete structures, which has great practical value in engineering application.

To understand the enhancing effect and fiber-reinforced mechanism of composite fibers reinforced cement concrete, the influences of composite fibers on micro-cracks and the distribution of composite fibers were evaluated by optical electron micrometer (OEM) and scanning electron microscope (SEM). Three kinds of fiber, such as polyacrylonitrile-based carbon fiber, basalt fiber, and glass fiber, were used in the composite fibers reinforced cement concrete. The composite fibers could form a stable structure in concrete after the liquid-phase coupling treatment, gas-liquid double-effect treatment, and inert atmosphere drying. The mechanical properties of composite fibers reinforced concrete (CFRC) were studied by universal test machine (UTM). Moreover, the effect of composite fibers on concrete was analyzed based on the toughness index and residual strength index. The results demonstrated that the composite fibers could improve the mechanical properties of concrete, while the excessive amount of composite fibers had an adverse effect on the mechanical properties of concrete. The composite fibers could significantly improve the toughness index of CFRC, and the increment rate is more than 30%. The composite fibers could form a mesh structure, which could promote the stability of concrete and guarantee the excellent mechanical properties.

The use of the thermal power plant ashes including fly ash (FA) and bottom ash (BA) for producing unfired building bricks (UBB) using sodium hydroxide (NaOH) solution as an alkaline activator was investigated. A low applied forming pressure of 0.5 MPa and various NaOH concentrations of 5, 8, 10, and 12 M were used for the preparation of brick samples with different solution-to-binder (S/B) ratios of 0.35 and 0.40. The bricks were subjected to various test programs with reflecting the effect of both NaOH concentrations and S/B ratios on the brick’s properties. The compressive strength, unit weight, ultrasonic pulse velocity, and thermal conductivity of bricks increased with increasing NaOH concentration, whereas the contrary trend was found with increasing S/B ratio. Also, the water absorption of bricks was observed to reduce with increasing NaOH concentration and decreasing S/B ratio. As the results, the combined utilization of both low forming pressure and coal power plant ashes can produce the UBBs with low unit weight, low heat conductivity, and acceptable strength and water absorption rate as stipulated by TCVN 6477–2016. Furthermore, the outcomes of chemical analysis and microstructure observation also demonstrate that a high concentration of the NaOH promoted the geopolymerization process. Notably, the use of NaOH solution of either 10 M or above is recommended for the production of UBBs, which are classified as grade M5.0 or higher.

The water absorption and desorption processes of different types of lightweight aggregates were studied. Subsequently, the influences of pre-wetting lightweight aggregates on compressive strength, microhardness, phase composition, hydration parameters and micromorphology of the cement pastes were investigated. The results showed that the water absorption and desorption capacities of the lightweight aggregates increased with the decrease of the densification degree. With the addition of pre-wetting lightweight aggregates, the compressive strength of the cement pastes would increase. Moreover, the enhancement effect was more obviously with the desorption capacity of pre-wetting lightweight aggregates increasing. Especially, sample S1 with pre-wetting red-mud ceramisites had the highest compressive strength, of which increased to 49.4 MPa after 28 d curing age. The reason is that mainly because the addition of pre-wetting lightweight aggregates can promote the generation of C–S–H gels in the interfacial zone, and the hydration degree of the interfacial zone increases with the water desorption of pre-wetting lightweight aggregates increasing. It is contributed to optimize the microstructure to enhance microhardness of the interfacial zone, resulting in the compressive strength of the cement-based materials improving. Therefore, the pre-wetting lightweight aggregates with high porosity and strength are the potential internal curing agents for high-strength lightweight concretes.

The feasibility of utilizing molybdenum tailing and diatomite as siliceous materials to prepare calcium silicate board was explored. The influences of molybdenum tailing/diatomite proportion on hydration characteristics, thermal conductivity, water absorption, flexural strength and moisture adsorption-desorption property of calcium silicate board were investigated in detail. The experimental results reveal that molybdenum tailing is environmentally friendly to prepare building materials. The main hydration products in calcium silicate board under autoclaved condition are C-S-H with low crystallinity and tobermorite. Molybdenum tailing is favorable to the formation of tobermorite. The flexural strength and bulk density of the calcium silicate board gradually increase when the content of molybdenum tailing increases. Netlike C-S-H is formed with the increase of diatomite content during autoclaved curing process, resulting in the enhancement of moisture adsorptiondesorption performance and the reduction of thermal conductivity. The optimal content of molybdenum tailing is 20%, furthermore, the flexual strength and thermal conductivity of calcium silicate board at this content meet the Chinese standard JC/T564.1-2008.

Salt attack performance of magnesium oxychloride cement (MOC) in brine was investigated from the viewpoints of strength development and strength coefficient. Microstructure was studied using quantitative X-ray diffraction (QXRD), thermogravimetry (TG) and scanning electron microscopy (SEM). The results show that MOC mortars have outstanding salt attack performance after aging brine and raw brine immersion. The salt attack coefficients of MOC mortars are higher than 0.8, which is qualified for application in saline soil and salt lake area. The reason is that salt brine solution enters into the voids of MOC and plays a role of toughening and strengthening in the MOC.

A high strength self-compacting pervious concrete (SCPC) with top-bottom interconnected pores was prepared in this paper. The frost-resisting durability of such SCPC in different deicing salt concentrations (0%, 3%, 5%, 10%, and 20%) was investigated. The mass-loss rate, relative dynamic modulus of elasticity, compressive strength, flexural strength and hydraulic conductivity of SCPC after 300 freeze-thaw cycles were measured to evaluate the frost-resisting durability. In addition, the microstructures of SCPC near the top-bottom interconnected pores after 300 freeze-thaw cycles were observed by SEM. The results show that the high strength SCPC possesses much better frost-resisting durability than traditional pervious concrete (TPC) after 300 freeze-thaw cycles, which can be used in heavy loading roads. The most serious freeze-thaw damage emerges in the SCPC immersed in the 3% of NaCl solution, while there is no obvious damage in 20% of NaCl solution. Furthermore, it can be deduced that the high strength SCPC can be used for 100 years in a cold environment.

During the process of liquid forging, a host of hot cracking defects were found in the Al-Cu-Mg-Zn aluminum alloy. Therefore, mechanical tests and analyses by optical microscope, scanning electron microscope, and X-ray diffraction were performed to research the influences of zinc, magnesium, and copper (three main alloying elements) on hot cracking tendency and mechanical properties. It was concluded that all the three alloying elements exerted different effects on the performances of newly designed alloys. And the impact of microstructures on properties of alloys was stronger than that of solution strengthening. Among new alloys, Al-5Cu-4.5Mg-2.5Zn alloy shows better properties as follows: σb=327 MPa, δ=2.7%, HB=107 N/mm², and HCS=40.

Diffusion bonding between Al and Cu was successfully performed by hot isostatic pressing (HIP). To improve the strength of diffusion bonding joint, pure nickel foils with different thickness were used as intermediate layer. Microstructure of the interface between Al and Cu was investigated by X-ray diffraction (XRD) technique, secondary electron microscopy (SEM), and nano-indentation tests. When the temperature was 500 °C and held for 3 h with a processing pressure of 50 MPa, Al and Cu could be bonded with its interface formed by several diffusion layers. With the addition of Ni interlayer, the diffusion of aluminum atoms was effectively hindered, and the interface became smoother. The tensile strength of bonded joints increases with increasing the thickness of Ni interlayer, which contributes to a reduction in the thickness of intermetallic compounds (IMCs) and well bonding quality of Al-Cu joints.

In order to study the high temperature flow behaviour of the V modified 2.25Cr-1Mo steel plate to guide the industrial rolling practice, the hot compression tests were carried out at the temperatures from 900 °C to 1150 °C and the strain rates from 0.01 s⁻¹ to 1 s⁻¹ on Thermecmastor-Z equipment. Based on the experimental data of the hot compression tests, a kind of Arrhenius-type constitutive equation was developed. The equation can accurately show the relationship between the flow stress and the deformation temperature, the strain and the strain rate. The measured true stress-true strain curves exhibit two kinds of flow stress curves. Moreover, the forming mechanisms of these two types curves were explained by softening, wok hardening theory as well as metallographic and hardness experimental results. The accuracy of the developed Arrheniustype constitutive equation was identified by three kinds of statistic parameters and also by comparison of the measured and predicted data. The reasonable value of the three types of statistic parameters and the good agreement between the experimental and predicted data can confirm the validity of the developed Arrheniustype constitutive equation for V modified 2.25Cr-1Mo heat resistant steel plate.

Dynamic compression tests were carried out to investigate dynamic mechanical behavior and adiabatic shear bands in ultrafine grained (UFG) pure zirconium prepared by equal channel angular pressing (ECAP) and rotary swaying. The cylindrical specimens were deformed dynamically on the split Hopkinson pressure bar (SHPB) at different strain rates of 800 to 4 000 s-1 at room temperature. The temperature distribution of the shear bands was estimated on the basis of temperature rise of uniform plastic deformation stage and thermal diffusion effect. The results show that the true stress-true strain curves of UFG pure zirconium are concave upward trend of strain in range of 0.02-0.16 due to the effects of strain hardening, strain rate hardening and thermal softening. The formation of the adiabatic shear bands is the main reason of UFG pure zirconium failure. A large number of micro-voids are observed in the adiabatic shear bands, and the macroscopic cracks develop from the micro-voids coalescence. The fracture surface of UFG pure zirconium exhibits quasi cleavage fracture with the characteristic features of shear dimples and river pattern. The highest temperature within the shear bands of UFG pure zirconium is about 592 K.

Based on the ABAQUS / Explicit finite element method, the forming force changing trend of deep drawing test for 6A16 aluminum alloy plate after pre-aging and storage at room temperature for one month was simulated under friction coefficient ranging from 0 to 0.22. The lubricants selected for the tests were mechanical oil, butter and dry film lubricant, and the friction coefficient of these lubricants were 0.05, 0.10 and 0.15, respectively. Microstructural evolution of 6A16 aluminum alloy plate during drawing forming was investigated by OM, SEM and EBSD. The results showed that, with the increase of friction coefficient, the stress, strain and deformation degree in deformation zone increased, while the grain size in deformation zone decreased. Thus, the hardness of the cup-typed component increased with the increase of friction coefficient. Butter-lubricated cups had the highest tensile strength and yield strength after paint-bake cycle. The combination of simulation results and microstructure analysis of 6A16 aluminum alloy plate after drawing forming indicates that the appropriate lubricant is butter.

To improve the low thermal conductivities and poor wear resistances of TC4 (Ti-6Al-4V) alloy, the most widely used titanium alloy, the surface of TC4 alloys is modified by electroplating deposition of Ni and Cu layers, and then heat-treated to increase the diffusivity at the interface. In this paper, the corrosion behavior of Cu/Ni coatings on TC4 alloy at different heat treatment processes was investigated in 3.5 wt% NaCl by the electrochemical analysis, and the microstructure and composition of corrosion products was carried out to reveal the corrosion resistance mechanism of Cu/Ni coatings. It was found that the corrosion resistance was significantly influenced by heat treatment temperature. With the increasing diffusion treatment temperature from 500 to 700 °C, the corrosion potential positively shifted from −330.87 to −201.14 mV, and the corrosion current density decreased from 4.02×10⁻³ to 0.514×10⁻³ mA/cm². However, when heat treatment temperature increased to 800 °C, the corrosion potential negatively shifted to -207.21 mV, and the current density increased to 1.62×10⁻³ mA/cm².The diffusion behavior of Ti, Ni and Cu elements occurred and small amounts of Ni and Ti elements appeared on the specimen surface under different heat treatment temperature. Especially heattreated at 700 °C, the smaller pore size, dense Cu₂O film, and highly stable TiO and NiO oxide layer were formed, which dramatically enhanced the corrosion resistance of Cu/Ni coatings. Finally, a novel model of corrosion resistance was proposed based on the analysis mentioned above.

The polycondensation of the mixture of diamines 5,5-methylene bis(2-aminophenol) and 4,4-(hexafluoroisopropylidene)dianiline (molar ratio 0.8:0.2) with isophthaloyl dichloride was used to synthesize poly(amido-o-hydroxy amide) (POA-F) - new heat resistant binder of the composites for microelectronics. The copolymer was fractionated, its hydrodynamic, optical, and conformational properties were researched, and molecular masses (ММ) of the fractions were defined. The polydispersity index was estimated. Based on experimental data, calculation of the size of a segment of Kuhn characterizing degree of an intramolecular orientation order and value of coefficients of the equation of Mark-Kuhn-Hauvink for viscometric and diffusion data were performed. It was demonstrated that introducing 20 mol % of the monomer with -CF3-groups does not lead to any changes in conformational properties of the macromolecules and does not change the degree of intramolecular orientational order (the Kuhn segment length). Optical characteristics of POA-F solutions are virtually similar to the corresponding values for POA prepared with the use of single amine-containing component-5,5-methylene bis(2-aminophenol). The received MM distribution for POA-F (prepolymer) provided the solubility of its films in alkaline solutions. The heat resistance (τ5 and τ10-temperatures corresponding to 5% and of 10% PBO-F mass loss of a polymer) of the powders and the films of PBO, PBO-F were determined. The electrophysical parameters-dielectric permittivity (ε) and dielectric loss tangent (tan δ) of the PBO-F films decreased down to 3.30 and 0.017, in comparison 3.40 and 0.025 for PBO respectively.

The composite phase change material (PCM) consisting of phase change paraffin (PCP) and polymethyl methacrylate (PMMA) was prepared as a novel type of shape-stabilized PCM for building energy conservation through the method of bulk polymerization. The chemical structure, morphology, phase change temperature and enthalpy, and mechanical properties of the composite PCM were studied to evaluate the encapsulation effect of PMMA on PCP and determine the optimal composition proportion. FTIR and SEM results revealed that PCP was physically immobilized in the PMMA so that its leakage from the composite was prevented. Based on the thermo-physical and mechanical properties investigations, the optimal mass fraction of PCP in the composite was determined as 70%. The phase change temperature of the composite was close to that of PCP, and its latent heat was equivalent to the calculated value according to the mass fraction of PCP in the composite. For estimating the usability in practical engineering, thermal stability, reliability and temperature regulation performance of the composite were also researched by TG analysis, thermal cycling treatments and heating-cooling test. The results indicated that PCP/PMMA composite PCM behaved good thermal stability depending on the PMMA protection and its latent heat degraded little after 500 thermal cycling. Temperature regulation performance of the composite before and after thermal cycling was both noticeable due to its latent heat absorption and release in the temperature variation processes. The PCP/PMMA phase change plate was fabricated and applied as thermal insulator in miniature concrete box to estimate its temperature regulation effect under the simulated environmental condition. It can be concluded that this kind of PCP/PMMA shape-stabilized PCM with the advantages of no leakage, suitable phase change temperature and enthalpy, good thermal stability and reliability, and effective temperature regulation performance have much potential for thermal energy storage in building energy conservation.

The in-plane compressive characteristics of the ultra-high molecular weight polyethylene (UHMWPE) fibre (Dyneema®) reinforced composites, both in 0/90° and ±45° fibre orientations with respect to the loading direction, have been investigated. The composite made from unidirectional high modulus fibres (volume fraction 83%) and low strength polyurethane matrix (volume fraction 17%) is layered in an orthogonally alternating manner. The different failure mechanisms for the composites with 0/90° and ±45° fibre orientations have been detected with the methods of experimental measurement, SEM observation and theoretical analysis. The composites specimens of 0/90° fibre orientation failed with macro-buckling of the high-modulus UHMWEP fibre layers with the matrix damage, whereas the specimens of ±45° fibre orientation failed with the shearing of the soft matrix. Hence, the composite specimens in 0/90° fibre orientation had higher stiffness as well as compressive strength than those in ±45° fibre orientation. The failure criteria of the composites under in-plane compression was employed to characterize the failure mechanism. Compared with the traditional thermoset matrix, the soft thermoplastic matrix leads to lower strength and higher failure strain of fibre reinforced composites under in-plane compression. In addition, the composite specimens cut by waterjet machine exhibited higher stress levels than those cut by bandsaw that introduced more initial imperfections with the temperature rising and tensile shocking. The comparison between the methodologies for cutting the tough composites can provide a valuable suggestion to obtain required composite structures without reducing the mechanical properties.

Three-dimensional porous poly-lactic acid (PLA) scaffold was fabricated using fused deposition modeling (FDM) method including 30%, 50% and 70% nominal porosity. Study of phases in initial polymeric material and printed scaffolds was done by X-ray diffraction (XRD), and no significant phase difference was observed due to the manufacturing process, and the poly-lactic acid retains its crystalline properties. The results of the mechanical properties evaluation by the compression test show that the mechanical properties of the scaffold have decreased signifcantly with increasing the porosity of scaffold. The microstructure of scaffolds were studied by scanning electron microscope (SEM), showing that the pores had a regular arrangement and their morphology changed with porosity change. The mechanical properties of the poly-lactic acid scaffolds printed using fused deposition modeling, can be adapted to the surrounding tissue, by porosity change.