The titanium coatings were prepared on Al₂O₃ balls by mechanical coating technique (MCT), and then the coatings were oxidized to titanium oxides(TiO₂) films at 300–600 °C. The effects of different milling time and oxidation temperature on thickness of films were studied. The composition and microstructure of the films were analyzed by scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). The results show that the thickest coatings with an average thickness of 20 µm were obtained at the milling time of 15 h. In addition, with the increase of the oxidation temperature, the oxidation of the film is increased. When the milling time is 15 h, the oxidation temperature is 500 °C, and the addition of photocatalyst is 1 g/mL. The films have the best photocatalytic performance when the degradation rate of methyl orange solution reaches the maximum value of 74.9 %, and the films have a good reusability.

Sialon/SiC composites were synthesized in situ from SiC, α-Si₃N₄, AlN, calcined bauxite, quartz and Y₂O₃ via layered buried sintering at different temperatures (1 540–1 640 °C). The results showed that the O’-sialon/SiC sample with 60 wt% silicon carbide sintered at 1 600 °C exhibited excellent mechanical properties, with apparent porosity of 16.01%, bulk density of 2.06 g·cm⁻³, bending strength of 52.63 MPa, and thermal expansion coefficient of 5.83×10⁻⁶ °C⁻¹. The oxide film formed on the surface was linked closely to O’-sialon, so the oxide film was not easily broken. After 100 h oxidization, the sample surface was smoother and denser, with oxidation weight gain rate 23.6 mg/cm² and oxidation rate constant 2.0 mg²·cm⁻⁴·h⁻¹. Therefore, the sample had the excellent high-temperature oxidation resistance. It was confirmed that the in-situ sialon/SiC composites could be a promising candidate for solar absorber owing to its high-temperature oxidation resistance.

Ga-doped Yttrium Iron Garnet (Y₃Ga _xFe_5−xO₁₂, Ga:YIG) was prepared by solid state reaction method and sintering at 1 300 °C. Rietveld analysis of X-ray diffraction patterns indicated that all samples crystallized in a single cubic structure (space group Ia-3d) with decreasing lattice constant as Ga concentration increased. SEM surface micrograph images of YIG samples showed highly compacted grains with small reduction in the grain size with increasing Ga concentration. Raman spectroscopy measurements confirmed the replacement of Fe³⁺ ions by Ga³⁺ ions in the garnet structure was revealed by the observed blue shifts in Raman spectra. The saturation magnetization decreased from 28.2 to 4.98 emu g⁻¹ with increasing x from 0.0 to 1.0 due to the preferential substitution of Ga³⁺ ions for Fe³⁺ ions at tetrahedral sites. Room temperature Mössbauer spectra for the samples revealed a reduction of the hyperfine field values for octahedral and tetrahedral sites, and the development of additional components with increasing Ga concentration. Analysis of the magnetic data and Mössbauer spectra confirmed that spin canting in the substituted garnets plays an important role in explaining the observed reduction of the saturation magnetization as x increased.

Lithium carbonate (Li₂CO₃) was synthesised by adding sodium (Na) and magnesium (Mg) ions into a lithium chloride solution at different concentrations, followed by the addition of an appropriate sodium carbonate solution. Then, the morphology, purity and particle size of Li₂CO₃ crystals were investigated. The Na and Mg ions had negligible and remarkable effects, respectively, on the product purity; however they both greatly influenced its morphology. Their effects on the nucleation and growth rates, the radial distribution function and the diffusion behaviour of the synthesised Li₂CO₃ were investigated via molecular dynamics methods; the Na ions slowed down the crystal nucleation and growth rates, while the Mg ions accelerated them. Moreover, the Mg ions rendered the system short-range ordered and long-range disordered and also increased the diffusion coefficient. The results of this study showed that Mg ions are one of the most important factors influencing the purity and yield of Li₂CO₃.

The dynamic characteristics of high sensitivity temperature sensor are studied by using siphon method to fill the air hole near the core of the hollow photonic crystal fiber with Cargille matching liquid, and the two ends are fused with single-mode fiber in this work. We analyzed the working principle of filled photonic crystal fiber sensor by using the standard coupling mode theory of directional coupler. The coupling process was simulated by COMSOL software. When the photonic crystal fiber filled with 10 mm liquid was scanned by tunable laser, the temperature sensitivity was 7.50 nm /°C, the average temperature response time was 0.317 s, the average release time was 3.732 s, and the temperature variation linearity was 100%. The experimental results show that the liquid filled photonic crystal fiber has the advantages of high temperature sensitivity, fast response time and good linearity.

Ce³⁺/Tb³⁺ co-doped and Ce³⁺/Tb³⁺/Eu³⁺ tri-doped β-NaYF₄ photoluminescent microcrystals using oleic acid as surfactant were synthesized using the solvothermal method. Their microstructural characteristics and photoluminescence properties were investigated in detail. They have the shape of hexagonal prism bipyramids with uniform particle size, which decreases with the concentrations of Tb³⁺ and Eu³⁺. The energy transfer processes of both the Ce³⁺→Tb³⁺ and the Ce³⁺→Tb³⁺→Eu³⁺ were systematically studied. Compared with Eu³⁺ or Tb³⁺ single-doped β-NaYF₄ microcrystals, the sensitization by Ce³⁺ for the photoluminescence of Tb³⁺ and Eu³⁺ leads to a broad excitation spectral bandwidth in the ultraviolet (UV) range. Meanwhile, the corresponding optical absorption efficiency is greatly enhanced. High energy transfer efficiencies have been observed from Ce³⁺ to Tb³⁺ and from Tb³⁺ to Eu³⁺.

The epoxy resin (E-51) was used as polymer matrix, conductive carbon black (CB) as conductive filler, and PZT was used to prepare a composite by curing. The effects of PZT and CB content on the properties of PZT/ CB/ EP piezoelectric composite were studied. When the PZT content reaches 40 wt%, the optimized vibration attenuation properties of PZT/CB/EP materials could be achieved with a loss factor of 0.9 from room temperature to 60 °C. With the increase of PZT content, the bending strength of PZT/CB/EP piezoelectric composite vibration reduction material firstly increased from 45 MPa to 65 MPa and then decreased to 38 MPa. At room temperature, the dielectric constant increased from 7 to 50, and the dielectric loss increased from 0.1 to 0.5.

Sodium dihydrogen phosphate (NaH₂PO₄) and potassium dihydrogen phosphate (KH₂PO₄) were selected as additives for magnesium oxysulfate (MOS) cement. The phase composition and the microstructure of MOS cement were characterized using X-ray diffraction (XRD), thermogravimetric analysis (TG-DSC), Flourier transform infrared spectroscopy (FT-IR), mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). It is found that both NaH₂PO₄ and KH₂PO₄ lead to an increase in the compressive strength and an improvement in the volume stability of MOS cement. The XRD, MIP and SEM results show that the addition of NaH₂PO₄ or KH₂PO₄ does not change the phase composition of MOS cement but promotes the formation of strength phase of 5Mg(OH)₂·MgSO₄·7H₂O (5·1·7 phase). This phase brings a considerable improvement in the microstructure of MOS cement, which has a positive effect on the properties of MOS cement.

The characteristics of surface appearances, mass loss, relative dynamic modulus of elasticity and strength loss of different recycled aggregate concretes(RAC) exposed to freeze-thaw cycles were analyzed. It was found that the freeze-thaw resistance of RAC could be determined by the recycled aggregate compositions and admixtures. Both the saturation degree and the air void structure were the key factors influencing the freeze-thaw damage on concrete. Some major proposed freeze-thaw deterioration mechanisms were utilized to interpret the freeze-thaw damage on recycled aggregate concrete. Meanwhile, some potential measures to enhance the freeze-thaw resistance of concrete were summarized and discussed.

The C60 concrete blocks with surface crack damage under high temperature environment were soaked by adding appropriate amount of soybean urease into the CO(NH₂)₂-CaCl₂ solution, the soybean urease mineralized calcium carbonate were characterized, and the effect of repairing concrete surface crack damage were evaluated by the surface sedimentation of C60 concrete blocks in the study. The experimental results showed that the activity of soybean powder was statistically significant, and its productivity of urease was comparable with that of urease-producing bacteria. After immersion in a soybean solution, a layer of complete and continuous white sediment covered the concrete surface. The cracks on the concrete surface were completely shielded, and the rising temperature on infrared thermal image of the concrete after repair was lower than before. Besides, through analysis by SEM, EDS, and XRD, the products formed after repair were found to be calcite-type CaCO₃ with high purity, and the crystals exhibited different morphological features. The above results indicate that soybean urease can regulate and induce the formation of calcium carbonate, and the precipitate is innocuous and harmless, suitable for a new type of concrete crack repair material.

for the purpose of providing references for further research and practical application about the quality improvement of RCA, in this paper, various treatment methods were firstly classified into four categories: removing old mortar (OM), strengthening OM, multi-stage mixing methods, and combination methods. Thereafter, the improvement mechanisms and important conclusions of various treatment methods were elucidated and summarised respectively. In the section of discussion, the improved effects as well as advantages and disadvantages of various treatment methods were compared and discussed respectively, and recommendations for the selection of treatment methods were proposed. Finally, the further research directions were pointed out, and an integrative programme on the quality improvement of RCA was recommended.

To further strengthen the protective effect of aerogel cement paste (ACP) coating on self-compacting concrete (SCC) in tunnel fire under the optimal mix proportion, the effect of curing temperature (from 5 to 80 °C, based on site construction curing temperature and surrounding rock temperature) on fire insulation of ACP was investigated. The mechanical properties, thermal conductivity and porosity of ACP were tested. The microstructure of ACP was characterized by means of SEM, XRD and TG/DTG. The results reveal that 50 °C is the optimal curing temperature for ACP with good mechanical properties and fire insulation. Relatively high curing temperature can facilitate hydration and pozzolanic reactions, contributing to the generation of more stable substances (such as C-S-H gels, tobermorite and thenardite, etc). ACP under excessive low curing temperature brings inhomogeneous microstructure with coarse pores, leading to producing wider and longer microcracks when it is exposed to tunnel fire. The microcracks make the heat convection and thermal radiation more significant and thus accelerate the damage of ACP under fire. In case of the less than 7% difference of thermal conductivity, dense microstructure and stable substances are more conducive to strengthening fire insulation of ACP. In practical engineering applications, the thickness of protective layer of ACP can be further optimized when ACP is cured under about 50 °C.

C-S-H series are synthesized at different temperatures and ages by pozzolanic reaction. The change of particle size distribution, phase composition, morphology and nanostructure of C-S-H with temperatures and ages, and the effects of C-S-H seeds and seeds parameters on the hydration behavior and mechanical properties development of cement were investigated by DLS, XRD, SEM, ²⁹Si NMR, TAM-air isothermal calorimeter and mechanical properties test. The results show that the particle size, crystallinity, basal spacing and Q ²/Q ¹ ratio of C-S-H increases with the increase of synthesis temperature and age. The addition of synthesized C-S-H seeds to cement pastes results in the strong acceleration effect on cement hydration and significant improvement of the early strength of cement paste and mortar. The 1 day-C-S-H seeds synthesized at room temperature can increase the strength of cement paste by about 30 MPa at 12 h. The effect does not show a very regular change with the increase of the temperature and age of seeds synthesis. Considering the effect of C-S-H seeds on the hydration and mechanical properties of cement, and economy and short cycle of seeds synthesis, the C-S-H seeds synthesized at room temperature for 1 day or 55 °C water bath for 12 hours is recommended.

A novel Fe-enriched lamella sandwich phase (χ-phase) has been found to precipitate along the basal (0001)_Mg planes in the heat-treated Mg-Gd-Fe alloy and its structure is clearly revealed by means of atomic-resolution transmission electron microscopy. The layered χ-phase only has a thickness of mono-unit-cell and consists invariably of ten atomic layers stacking along the [0001]_Mg direction, of which the outermost atomic layers had larger in-plane atom-pillar spacing than the inner layers. Fe/Gd atoms are mainly enriched in the outer four atomic layers in the χ-phase, forming two structurally unsymmetrical four-layer shells to sandwich the middle two Mg layers. An atomic model has been proposed for this layered sandwich-structured χ-phase.

The PrMg₁₂-type composite alloy of PrMg₁₁Ni + x wt% Ni (x = 100, 200) with an amorphous and nanocrystalline microstructure were synthesized through the mechanical milling. Effects of milling duration and Ni content on the microstructures and electrochemical hydrogen storage performances of the ball-milled alloys were methodically studied. The ball-milled alloys obtain the optimum discharge capacities at the first cycle. Increasing Ni content dramatically enhances the electrochemical property of alloys. Milling time varying may obviously impact the electrochemical performance of these alloys. The discharge capacities show a significant upward trend with milling duration prolonging, but milling for a longer time more than 40 h induces a slight decrease in the discharge capacity of the x = 200 alloy. As milling duration increases, the cycle stability clearly lowers, while it first declines and then augments under the same condition for the x = 200 alloy. The high-rate discharge abilities of the ball-milled alloys show the optimum values with milling time varying.

The simulation of hydrogen purification in a mixture gas of hydrogen/carbon dioxide (H₂/CO₂) by metal hydride system was reported. The lumped parameter model was developed and validated. The validated model was implemented on the software Matlab/Simulink to simulate the present investigation. The simulation results demonstrate that the purification efficiency depends on the external pressure and the venting time. An increase in the external pressure and enough venting time makes it possible to effectively remove the impurities from the tank during the venting process and allows to desorb pure hydrogen. The impurities are partially removed from the tank for low external pressure and venting time during the venting process and the desorbed hydrogen is contaminated. Other parameters such as the overall heat transfer coefficient, solid material mass, supply pressure, and the ambient temperature influence the purification system in terms of the hydrogen recovery rate. An increase in the overall heat transfer coefficient, solid material mass, and supply pressure improves the hydrogen recovery rate while a decrease in the ambient temperature enhances the recovery rate.

The microstructure and microhardness of ADC12 alloy that was mixed with 0, 0.3, 0.6, and 0.9 wt.% rare earth praseodymium/cerium (Pr/Ce) were studied. The addition of Pr/Ce improved the microhardness of the alloys. The ADC12+0.6 wt% Pr/Ce alloy displayed the smallest grain size and maximal microhardness. The tribological behavior of the alloys was tested by the pin-on-disc dry sliding friction pair with a sliding velocity of 0.21 m/s under various loads (20,40,60,80 N). The wear morphology was observed by a scanning electron microscope (SEM) and the wear mechanism was discussed. The result indicated that the wear resistance of ADC12+0.6 wt% Pr/Ce alloy was the most optimal. The wear rate relative to the matrix is reduced by 67.5% under a load of 20 N. The wear mechanism is adhesive wear.

The effects of modifiers on the anti-wetting and anti-icing property of the prepared rough aluminum surface were investigated. The rough aluminum substrates were obtained through electrochemical oxidization with 15 wt% sulfuric acid solution as the electrolyte at the constant current of 4 mA for 3 h. And then they were modified with octadecanoic acid (C18), polyethylene (PE), polystyrene (PS), polyethylene glycol (PEG) and hexamethylenetetramine (HMTA), respectively, whose surface free energies were 27.6, 31.0, 33.0, 61.6 and 70.0 mN/m, respectively. The contact angles (CA) were 154.6°, 128.4°, 127.6°, 5.0° and 0.0°, respectively, and the ice adhesion pressures were 15.9, 36.3, 55.9, 155.3 and 216.1 kPa, respectively. The ice adhesion strengths decrease along with the increasing anti-wetting property of aluminum surfaces and the decreasing of the surface energy of modifiers. These provide some new insights when designing the aluminum surface with anti-icing properties in some special applications.

A halogen-free flame-retardant (hydroquinone bis (N, N’-diarylphosphoramidate), 4N-HDP) containing phosphorus-nitrogen was synthesized. Its structure was characterized by infrared spectroscopy (IR), nuclear magnetic resonance (¹H-NMR and ³¹P-NMR). Thermogravimetric analysis (TG), limiting oxygen index (LOI), UL-94 vertical burning test (UL-94), thermogravimetric-infrared instrument (TG-IR) and scanning electron microscopy (SEM) were used to compare the flame-retarding performance and mechanism of hydroquinone bis (diphenyl phosphate) (HDP) and 4N-HDP. TG, IR and TG-IR were used for comparative analysis, indicating that both HDP and 4N-HDP are flame-retardants, and the gas phase and condensed phase act synergistically. In the pyrolysis process, it is divided into two steps: the first step is the breakage of large molecules to small molecules; the second step is the gasification and carbonization of small molecules, and eventually produces phosphate ester and non-flammable gases. Through the comparison of various results, it could be found that 4N-HDP has better flame-retarding performance compared to HDP in the composite with polycarbonate (PC).