Along with the long preparation cycle time and high cost of conventional preparation methods, the inherent high thermal conductivity of TiCoSb Half-Heusler alloy limited its commercial application. Herein, Ti_1-xNb_xCoSb Half-Heusler alloys with low thermal conductivity were successfully prepared by microwave synthesis combined with rapid hot-pressing sintering, which substantially shortened the preparation cycle and increased the density of TiCoSb Half-Heusler alloys. Furthermore, we studied the effects of Nb substitution at Ti sites on the phase composition, composition distribution, and thermoelectric transport properties of Ti_1-xNb_x CoSb Half-Heusler thermoelectric materials. Additionally, the figure of merit(ZT) of Ti_1-xNb_x CoSb samples were considerably optimized under the combined effects of increasing power factor and decreasing lattice thermal conductivity. The results showed that the Ti_0.93Nb_0.07CoSb sample had a maximum ZT of 0.1 at 725 K, which was two orders of magnitude higher than that of the TiCoSb sample prepared by the same process.

In this paper, graphene prepared by liquid-phase stripping assisted by tannic acid achieved better dispersion than ordinary graphene. The new graphene can meet the requirements of low cost, high output, and environmental protection. Graphene-SiO₂ hybrid materials were obtained by reacting SiO₂ treated with silane coupling agent (KH550) modification and graphene modified with tannic acid to form strong hybridization bonds, and the success of obtaining graphene-SiO₂ hybrid materials was confirmed by infrared spectroscopy. Furthermore, the mechanical properties of graphene-SiO₂ hybrid material in styrene-butadiene/polybutadiene composites were studied. In addition, the mechanical properties and the electrical and thermal conductivity of the blend of conductive carbon black and graphene-SiO₂ hybrid material in styrene-butadiene/polybutadiene composite were investigated. The results show that: at the addition of 1 part per hundred(phr) of graphene-SiO₂ hybrid material, the butadiene/cis rubber composites obtained relatively good wear resistance, if the loading is more than 1 phr, the graphene fillers will easily reaggregate with each other, resulting in an increase in wear volume compared with the blank control group. Moreover, when 8 phrs of self-made graphene were added, the conductivity increased by 1 000 times, and the antistatic properties of rubber composites were considerably improved.

Silica (mainly comprising nano-SiO₂) is widely used in rubber reinforcement owing to its advantages of easy preparation and environmental protection. However, owing to its structural characteristics, silica has poorer dispersion and reinforcement ability than carbon black. The purpose of this paper is to present a proposal to improve the dispersion of silica in rubber using a silane coupling agent and to study the effect of synergistic reinforcement of modified silica and graphene on natural rubber. The hybrid filler KS-TGE was obtained through a Michael addition reaction between graphene modified by dispersant tannic acid and silica (KS) modified by the silane coupling agent KH570. Subsequently, the KS-TGE/NR composites were prepared by mixing KS-TGE with natural rubber. Test results showed that the modified silica improves the dispersion in rubber and the mechanical properties of natural rubber after blending with the hybrid filler prepared using graphene and natural rubber. Compared with unmodified nano-SiO₂/NR, the tensile strength of the modified composites increased by 36.3% and the elongation at break increased by 79.5%. In addition, KS-TGE/NR can maintain excellent elastic and dynamic mechanical properties.

In this paper, the preparation process of N-propylethylenediamine bonded silica gel (PSA) with controllable bonding amount was optimized; the batch repeatability of PSA preparation was examined; and the pilot scale-up experiment of PSA preparation was conducted. The properties of the PSA were investigated by infrared spectroscopy, elemental analysis, and potentiometric titration. The results showed that N—H stretching vibration peaks appeared at 3 460 cm^-1, asymmetric and symmetric stretching vibration peaks of —CH appeared at 2 960 cm^-1 and 2 860 cm^-1, and deformation vibration absorption peaks of —NH₂ appeared at 708 cm^-1, indicating that N-propylethylenediamine was successfully grafted onto the surface of silica gel.Furthermore, with the increasing proportion of silane reagent in the preparation system, the content of carbon, nitrogen, and hydrogen elements and the ion exchange capacity obtained by potentiometric titration showed an upward trend, indicating that the bonding amount of ethylenediamine-N-propyl functional group gradually increased. Moreover, the prepared PSA packing component was separated from the purification column, and the removal efficiency of ginkgolic acid from the extract of ginkgo biloba leaves using PSA with different bonding amounts was investigated. The results showed that PSA had a strong adsorption capacity for ginkgolic acid and could be used to remove ginkgolic acid from the extract of ginkgo biloba leaves, the maximum sample loading volumes for PSA separation and purification columns 2^#, 3^#, 4^#, and 5^# are 21, 22, 23, 24 mL, respectively. In addition, the removal efficiency was found to increase with the increasing amount of ethylenediamine-N-propyl bonding.

Polyvinyl chloride (PVC) foam board is prepared by extrusion foaming of PVC with low polymerization degree, and the PVC foam board is prone to curling movement along the force direction of the molecular chain due to environmental changes, resulting in shrinkage and deformation of the board. Heavy calcium carbonate (HCC) was used as raw material, polyvinyl alcohol (PVA) and tannic acid (TA) were used as modifiers to prepare modified HCC. It was combined with PVC to prepare PVC foam sheets. Infrared spectrometer, differential scanning calorimeter, scanning electron microscope, Vicat softening point tester and universal electronic stretching machine were used to characterize the foamed board, and the effect of modifier dosage on the dimensional stability of the foamed board was discussed. The results show that when the TA content is 3% of HCC, the glass transition temperature of PVC foam board is 88.1 ℃, the temperature of Vicat softening point is 75.21 ℃, and the PVC foam board has excellent dimensional stability, and the cell structure is stable and uniform, and has the best tensile strength of 6.17 MPa. Modified HCC particles have good dispersion, strong binding ability with PVC, and high dimensional stability of PVC foam board can replace the use of wood in home decoration boards, which is of great significance to protect the environment.

A lightweight and cooling woven fabric for summer was developed by selecting and combining different cooling fibers. Twelve samples were produced by selecting polyester/mint blended yarn as warp yarn, nylon fiber as weft yarn and plain, and twill and satin as fabric weave to investigate the impact of different weft yarns and fabric structures on the thermal and moisture comfort properties of the fabrics. The results showed that twill and satin fabrics had better thermal and moisture transfer performance; plain weave fabrics provided a good cooling sensation upon contact; cool nylon indeed enhanced the cooling of the fabric, but it showed poor moisture transfer performance in tightly woven structures. Micro-denier nylon had similar thermal and moisture transfer performance to cool-feel nylon but had lower air permeability and cross-sectional nylon had better moisture transfer performance but lower thermal conductivity.

The energy conversion efficiency of CH₃NH₃PbI₃ (MAPPbI₃) perovskite solar cells is closely related to the quality of the perovskite film. To obtain high quality perovskite films, the film preparation method and process were optimized. It was found that the green solvents, propylene glycol methyl ether acetate and glycerol, can promote nucleation of PbI₂ particles, provide heterogeneous nucleation sites for CH₃NH₃PbI₃ perovskite crystals, and thus facilitate the rapid growth of perovskite crystals. Compared to perovskite films treated with the common toxic solvent chlorobenzene, films treated with propylene glycol methyl ether acetate and glycerol have larger grain size, lower root-mean-square value, and greater surface roughness optimization. This can result in a uniform, full-coverage perovskite film that is close to the perovskite carrier diffusion length. The performance of devices under different treatment conditions was tested and it was found that compared to CH₃NH₃PbI₃ perovskite solar cells treated with chlorobenzene (energy conversion efficiency of 17.86%), the device treated with green solvent glycerol had the highest efficiency of 21.60%, which is an increase of nearly 21%. These experimental results have some reference value and guiding significance for researchers in this field to obtain environmentally friendly high-quality perovskite type solar cells in the future.

Inclusions have an impact on the fatigue strength and fatigue life of steel, but inclusions in large samples cannot be accurately imaged using X-ray micro computer tomo-graphy(X-ray micro-CT). This study provides a novel approach to obtain the three-dimensional morphology of inclusions in large steel samples. To realize the three-dimensional features of inclusions in large alloy samples, this study used a nonaqueous electrolysis method to obtain inclusions; then scanning electron microscopy was performed to observe and analyze the electrolyzed inclusions.Furthermore, the electrolyzed inclusions were aggregated into cylindrical samples and finally scanned with X-ray micro-CT to obtain their three-dimensional information, and the obtained dimensional data of the inclusions were statistically analyzed.

The Exfresh fiber is a new type of modified acrylic fiber with fine denier and antibacterial properties; it is fabricated by adding an antibacterial agent to the spinning stock solution. The surface morphologies, mechanical properties, moisture absorption properties, specific resistance, friction properties, and curling properties of the Exfresh and ordinary acrylic fibers were tested and compared in this study. The elemental composition and chemical bonds of the two fibers were analyzed via X-ray photoelectron spectroscopy (XPS). Furthermore, the moisture-absorbing quick-drying and moisture-absorbing heat-generating properties of the Exfresh blended fabrics were tested. Results showed that the Exfresh fiber featured a circular cross-section, rough longitudinal surface and dense grooves as well as a low linear density, excellent mechanical properties, and high spinnability. Additionally, it has a lower specific resistance and higher friction coefficient than the ordinary acrylic fiber, thereby making it difficult to produce static electricity. Results of the XPS analysis showed that the added antibacterial agent was a quaternary ammonium salt. Additionally, the evaporation rate of an Exfresh fiber-blended fabric is bigger than 0.18 g/h, and its maximum moisture-absorbing heat-generating temperature rise is bigger than 4 ℃. Moreover, it exhibits excellent moisture-absorbing quick-drying and moisture-absorbing heat-generating properties, and can be used to develop multifunctional fabrics.

EKS fiber is a subacrylate fiber with significant hygroscopic-heating properties. In this study, the surface morphologies of EKS and acrylic fibers were compared, and their mechanical properties, friction properties, specific resistance, curling properties, moisture absorption and liberation properties, and hygroscopic-heating properties were tested and analyzed. The results showed that compared with the acrylic fiber, the EKS fiber featured a circular cross section and rough longitudinal structure as well as low breaking strength, friction coefficient, specific resistance and curl rate; moreover, it featured a high linear density, elongation at break, and moisture recovery rate. With the initial absorption rate and liberation rate being 0.39% min^-1 and 8.94% min^-1, respectively, the moisture absorption and liberation rates of the EKS fiber decreased exponentially with time, and the time required to achieve the absorption and liberation balance was longer than that for the acrylic fiber. The EKS fiber exhibited good hygroscopic-heating properties with a maximum hygroscopic-heating value of 8.2 ℃, which was 4.7 ℃ higher than that for the acrylic fiber.

Because TiAl alloys are susceptible to fatigue cracking on their surfaces due to cyclic loading when used at high temperatures, it is necessary to treat their surfaces to improve their mechanical properties. In this study, TiAl alloy was subjected to shot peening tests at room temperature, using 0.2 mm diameter steel shots at 0.7 MPa air pressure. The shot peening simulation studies were conducted using ABAQUS finite element analysis software. Subsequently, the shot-peened specimens were heat treated at different temperatures and holding times. The cross-sectional microstructures of the specimens were observed using a scanning electron microscope (SEM), the residual compressive stresses on the surfaces were measured using an X-ray residual stress meter, and the surface microhardness after heat treatment was measured using a microhardness meter. The results showed that many pits and lamellar protrusions appeared on the surface of TiAl alloy after shot peening, and obvious plastic deformations and numerous deformation twins appeared at the secondary surface. The residual compressive stress on the surface of the TiAl alloy after heat treatment decreased as the holding time and heat treatment temperature increased. Hardness followed a similar trend as the residual stress; however, when the heat treatment temperature was raised to 1 200 ℃, the hardness increased due to the change of metallographic organization and a significant increase inα₂ phase content.

Several high-strength fastening bolts were found broken on a railway steel bridge. Failure analysis of these bolts was performed to determine why they fractured and to prevent future bolt fractures. The fracture morphology, microarea-chemical analysis of the fracture, microstructure and hardness of the bolts, compositional contents, and mechanical properties of the bolt steel were analyzed by using scanning electron microscopy, energy dispersive X-ray spectrometry, optical microscopy, a Rockwell hardness tester, X-ray fluorescence spectrometry, and an electronic universal testing machine, respectively. The results indicate that the compositional contents, hardness, and mechanical properties are consistent with the 20MnTiB steel standard. In addition, dendritic cracks can be observed in the fracture initiation zones of the fastening bolts and the corrosion products in the cracks contain sulfur.The fastening bolts are subjected to cyclic loads in normal working conditions. Therefore, fractures of the fastening bolts were caused by corrosion fatigue fractures under cyclic loads. The cracks initiated at the root of the screw thread or the connecting point between the stud and nut, which are particularly vulnerable to stress corrosion cracks caused by the presence of sulfur.

The effects of four solid-solution treatments on the microstructure and properties of Al-5.6Cu-1.7Mg-0.2Zr-0.1Sr-0.6Ti alloy were studied herein by metallographic structure analysis,SEM(Scanning Electron Microscope) analysis、X-Ray Diffraction,hardness,conductivity,room temperature tensile properties, elongation after fracture and intergranular corrosion resistance. The results show that the grain size increases and with an increase in the solution temperature. The size and quantity of insoluble phase in the alloy decrease with increasing solution temperature when the temperature is less than 520 ℃. When the solid treatment is 510 ℃ for 2 h and then at 520 ℃ for 2 h, the insoluble phase in the alloy begins to increase, and the alloy appears slight overburning, the elongation after fracture and intergranular corrosion resistance become worse, but the tensile strength reaches the highest as 490.14 MPa. The dislocation strength and dislocation contribution decrease with an increase in the solution temperature. The strength effect in the alloy is mainly attributed to the solution strengthening and aging precipitation strengthening.Two different solid-solution treatments (route a:490 ℃ for 2 h and then at 500 ℃ for 2 h; route b: 500 ℃ for 2 h and then at 510 ℃ for 2 h) both can guarantee the mechanical properties(strength and elongation) and intergranular corrosion resistance of the alloy under T6 aging are good; therefore,both of the solid-solution treatments are suitable for preparing Al-5.6Cu-1.7Mg-0.2Zr-0.1Sr-0.6Ti alloy.

Owing to the low visible-light utilization of traditional photocatalysts and the serious problem of photogenerated electron-hole recombination at the bulk/interface, two-dimensional Bi₂WO₆ nanosheets were prepared herein using the hydrothermal method. Based on the principle of energy-level matching, Cu₂S was grown on the surface of the two-dimensional Bi₂WO₆ nanosheets using the hydrothermal method to construct Bi₂WO₆-Cu₂S heterojunctions for improved light absorption. Based on the excellent piezoelectric properties of the nanosheets and the excellent optical absorption and carrier transport properties of the Bi₂WO₆-Cu₂S heterojunctions, a piezo-photoelectric synergistic catalytic system was constructed and the optimal degradation experimental conditions were explored. The Bi₂WO₆-Cu₂S material was successfully applied for the degradation of Rhodamine B(RhB) in water. The results showed that under the synergistic photoelectric-piezoelectric effect, the degradation rate of RhB by the designed Bi₂WO₆-Cu₂S reached 87% in 40 min. This study provides a new way for designing unique heterojunction structures via the synergistic action of photocatalysis and piezoelectric catalysis.

The working surface of a camshaft is easily worn during service, thus seriously affecting the normal operation of the machine. The pitting areas on the working surface of the camshaft were repaired using cold-welding equipment. A metallographic microscope was used to observe the microstructure of the repaired area, and the residual stress distribution and hardness distribution around the repaired areas were determined using an X-ray residual stress tester and a hardness tester, respectively. The results show that the repair welding spot is well combined with the matrix, the carbides precipitated from austenite are dispersed in the matrix structure, the position of the repair welding spot presents the minimum residual stress and the minimum hardness value, and the influence of the repair welding spot on the residual stress and hardness is maintained within around 4 mm of the repaired areas. The camshaft repaired via cold welding meets the service performance requirements.

Polyimide (PI), a type of high temperature-resistant polymer synthesized using dianhydride or diamine, has become one of the most industrialized polymer materials with the highest operating temperature owing to its strong high-temperature resistance property. However, the strength of PI films still needs to be improved for their industrial application. To improve the elongation rate and tensile strength of PI films, different methods, such as adjusting the concentration, ratio, addition method of precursors and the addition amount of biomass fibers, have been tested in our experiments.4,4-Diaminodiphenyl ether and 3,3,4,4-biphenyltetracarboxylic acid dianhydride were used as the precursors for the reaction. Polyamide acid was prepared using the positive addition method in the presence of a cross linker, which was then poured into a Petri dish containing uniform lotus root fiber. The PI film was obtained by calcination. The results showed that the final gage length and elastic modulus of the PI films containing lotus root fiber were lower than those of the pure PI film. Furthermore, PI-2% root-fiber film had a tensile elongation at break of 6.49%, a tensile strength of 67.33 MPa, and a maximum force tolerance.of 57.47 N, which are much higher than those of pure PI film. Thus, the addition of lotus root fiber enhances the mechanical properties of the film.

Herein, we are using polyamide 66 fiber to develop high performance and high quality denim fabric. Using viscose as the outer fiber, polyamide 66 or spandex as the core yarn to make 36.4 and 28.0 tex core-spun yarn as the weft yarn, pure cotton yarn of 36.4 and 28.0 tex as the warp yarn, a rapier loom is used to interweave to make the denim fabric. The strength, wear resistance, elastic recovery, crease recovery, and bending properties of denim fabrics woven from 6 kinds of fabrics waved by polyamide 66 core-spun yarns and spandex core-spun yarns were tested. Through comparative analysis, it is found that the elasticity of polyamide 66 core-spun denim is as good as that of spandex core-spun denim, while its strength and softness are better. Viscose/polyamide 66 (3.33 tex/10 F) core-spun fabric is stronger, more resilient, and softer than viscose/polyamide 66 (3.33 tex/34 F) fabric. Meanwhile, fabrics woven with 36.4 tex yarn have better strength, elasticity, and crease recovery, while fabrics woven with 28.0 tex yarn are softer.

Humidity is a significant environmental parameter in storage, civil explosives business, and other fields. The performance of humidity-sensitive materials directly determines the quality of sensors. Polyimide and polyvinyl alcohol, the most commonly used humidity-sensing materials in optical fiber humidity sensors, were selected as the research objects. The humidity sensors were fabricated by coating two different humidity-sensitive materials on the surface of the fiber Bragg grating and their sensitivity, response time, and long-term stability were tested and compared. Results show that the linearity of the humidity sensor coated with polyimide is 99.98%, the sensitivity is 5.4 pm/%, the response time is 9.7 min, and the maximum wavelength shift is 5.6 pm. The humidity sensor coated with polyvinyl alcohol has a higher sensitivity in the range of relative humidity 60%~90%, which makes polyvinyl alcohol-based humidity sensors more suitable for humidity measurement in high-humidity environments.

The poor mechanical properties of hydrogel electrolytes and the freezing of water at low temperatures affect their ionic conductivity, thereby hindering their application in energy storage devices and electronic conductors. In this study, a type of antifreezing organic hydrogel with high mechanical properties and conductivity is fabricated. The electrolyte was synthesized via free-radical polymerization by adding soy protein isolates and using acrylamide and methacrylic ethyl sulfobetaine as monomers in a mixed solution of dimethyl sulfoxide/H₂O in the presence of lithium chloride. The fabricated hydrogel electrolyte exhibits good ionic conductivity (maximum 37.5 mS/cm), good mechanical properties (maximum stress 69 kPa and maximum strain 762.5%), and high toughness and fatigue resistance. Furthermore, the fabricated electrolyte shows a good response under varying strain and temperature conditions with a wide sensing window and good stability. Additionally, supercapacitors based on this electrolyte show good electrochemical performance between 20 ℃ and -20 ℃. In other words, at 20 ℃, the capacitances of the supercapacitor are 62.1 and 30 F/g at current densities of 0.2 and 5 A/g respectively, while at -20 ℃, the capacitance can maintain 59% of the value obtained at 20 ℃. Moreover, the supercapacitor can maintain 92% of the capacitance after 10 000 cycles, showing good cyclic stability.

In this study,the effects of different Sn contents on the microstructures and mechanical properties of Mg-5Zn-2.5Al-xSn(x=0, 1, 2, 3, 4) (ZAT52x) alloys were investigated. Curves of the mass fraction of liquid versus temperature during solidification of Mg-5Zn-2.5Al-xSn (x=0, 2, 4) (ZAT52x) were calculated using the Thermo-Calc software. It is found that α-Mg, Mg₂Sn (not precipitated when x=0), φ-Mg₂₁(Zn,Al)₁₇, τ-Mg₃₂(Zn,Al)₄₉, and MgZn precipitate in sequence during the solidification of ZAT52x magnesium alloy. As the Sn addition increases, the melting point of the ZAT52x alloy decreases and the amount of the second phases increases, and the tensile strength and elongation of the as-cast ZAT52x increased at first and then decreased. The as-cast ZAT522 alloy exhibits the best mechanical properties with tensile strength of 245.9 MPa and elongation of 14.4%. After extrusion, the ZAT522 alloy exhibits the highest tensile strength (376.2 MPa) and elongation (20.8%), while the ZAT524 alloy shows a more balanced mechanical property with tensile strength, yield strength, and elongation of 363.7 MPa, 260.4 MPa, and 17.9%, respectively.

To determine the degradation pattern of pore structures during concrete damage under different sulfate mass fraction, the freeze-thaw cycle test of concrete under different sulfate mass fraction is performed herein. Using nuclear magnetic resonance technology, the change in porosity during concrete damage is analyzed, in addition to the mass loss and relative dynamic elastic modulus change. The results show that the first peak of T₂ spectrum changes significantly under different sulfate mass fraction. In the same period of the freeze-thaw cycle, the change range of the T₂ spectrum first peak increases with increase in the sulfate mass fraction. An exponential relation exists between the first peak area of T₂ spectrum and the number of freeze-thaw cycles in the salt-freezing environment, and a linear relation exists in the water-freezing environment. There is a linear relation between the development of microporosity and the number of freeze-thaw cycles. There is a significant linear relationship between the porosity and the number of freeze-thaw cycles and sulfate mass fraction. The mass loss and the relative dynamic elastic modulus loss in the salt-freezing environment increase with increase in the sulfate mass fraction.

Herein, a novel type of high efficiency porcelain-aluminum composite solar plate (PACP) was developed, which comprised aluminum alloy matrix plates, flow guide collecting tubes and nanostructure endothermic coatings. The aluminum alloy matrix plate was an integrated structure of circulating pipes and curved fin plates and manufactured through a one-step extrusion process using corrosion-resistant 6063 aluminum alloy. The inner walls of the circulating pipes and diversion collecting pipes were protected by spraying superhydrophobic coating layers. The nanoblack porcelain composite powder was synthesized using black porcelain powders, matting agents, and resin binders. The nanostructure endothermic coating was prepared via electrostatic spraying and a high-temperature curing process. The solar absorptance was up to 0.96. The experimental results showed that the nanostructure endothermic coatings exhibited good thermal stability and would not peel off under long-term adverse environmental conditions. The porcelain-aluminum composite solar plates with an integrated structure exhibited excellent thermal conductivity, and the thermal conductivity efficiency was as high as 0.98. The thermal efficiency of the proposed porcelain-aluminum composite solar collector was approximately 43.6%, which was higher than that of traditional solar collectors, and the manufacturing cost was approximately 14% lower than that of traditional solar collectors. The proposed porcelain-aluminum composite solar collectors have advantages in terms of cost, life, and efficiency and can be used to build large-area solar collector systems to meet current development requirements of the solar energy industry. It has good economic and social benefits and broad application prospects.

The optimal heat-treatment parameters for the high-chromium cast iron blades of shot blasting machine were researched on the basis of the orthogonal experimental design. With the addition of trace elements, vanadium and nano-sized WC/TiC particles, the wear resistance of high-chromium (Cr) cast-iron casting was improved, thus extending its service life. The results indicated that the blades′ hardness was 60 HRC and its best wear resistance was obtained at a quenching soaking time of 3 h while temping at 450 ℃ for 2 h. By adding the trace elements, vanadium and nano-sized WC/TiC particles, the microstructure of the blade was refined, the carbide morphology was changed, and the wear resistence improved by 30%. Results showed that the wear resistance of high-Cr blades can be increased by optimizing the heat-treatment process and the blades′ composition, thereby proving the comprehensive benefit of this study in industrial applications.

In this study, the original vibration signals of an Svenska Kullager-Fabriken (SKF) bearing's inner race, rolling element, and outer race with three fault sizes were extracted from Case Western Reserve University Bearing Data Center. The fault sizes were 0.007, 0.014, and 0.021 in(1 in=2.54 cm). By empirical mode decomposition (EMD), 17 intrinsic mode functions were found. Principal component analysis (PCA) was then conducted, and it was found that the relationship between the fault sizes of the inner and outer races and the first and second principal components could be accurately fitted by principal component fitting formulas. Therefore, the fault sizes can be obtained by real-time monitoring of vibration signals and signal analysis. Finally, the residual life of the bearing with a fault was predicted using the Paris-Erdogan formula and finite element simulation. This study has a significant meaning for prevention of equipment accidents caused by bearing cracks.

In this study, an electromagnetically induced transparent metamaterial structure with four metal lines and a ring is proposed. It exhibits the characteristics of horizontal and vertical polarization insensitivity when the electromagnetic wave is perpendicular to its surface. The characteristics of the metamaterial transmission curve and its surface current distribution have been numerically calculated and simulated. Further, the phase propagation curve and group refractive index are calculated and analyzed. The maximum group refractive index can reach up to 380, indicating that the metamaterial can be used to fabricate slow optical devices. When this metamaterial is used to manufacture a refractive index sensor, the D_FOM value is approximately 20.13, indicating a higher sensitivity compared with those of the existing sensors. Results show that the metamaterial can be applied to manufacture slow optical devices and refractive index sensors.

The optimization and calculation of the phase diagram of a Ti-Nb-Zr ternary system were presented using Pandat software. The Gibbs energy of the pure component was described using the expression provided in the scientific group thermodata Europe database. The substitutional solution and two-sublattice models were used to describe the Gibbs energy of the liquid and solid solution phases, respectively. To improve the description of the Ti-Nb-Zr ternary system, the thermodynamic parameters of the Ti-Nb and Ti-Zr systems were obtained using the PanOptimizer module of Pandat software by considering experimental data on phase equilibrium and published thermodynamic properties. The calculations of the phase equilibrium and thermodynamic properties using the proposed description agreed well with the experimental data. The results have important directive significance to the development of Ti-Nb-Zr ternary system biomedical materials.

In the present study, the Bi(OTf)₃ catalyzed thia-Michael addition to ortho-quinone methides for the synthesis of ortho-hydroxybenzyl thioethers with 2-［hydroxy(phenyl)methyl］ phenols and vinyl thioethers in 1,2-dichloroethane was developed. The reaction could be achieved at 30 ℃ for 3 h and the products were obtained in moderate to good yields (78%~88%). The prominent features of the present strategy are good chemical selectivity and with wide substrate scope. For 2-［hydroxy(phenyl)methyl］ phenols, electron-withdrawing groups and electron-donating groups on aromatic rings could react soothly to obtain corresponding products. Also, the reaction could be achieved with phenyl vinyl thioether and ethyl vinyl thioether. Furthermore, the reaction could be scaled up to multigram scale.

To further optimize the corrosion resistance of biomedical magnesium alloys and meet clinical use requirements, surface modification was performed on a novel biomedical ZTM630 magnesium alloy with high strength and toughness via micro-arc oxidation. Micro-arc oxidized samples with oxidation times of 2, 5, 8, and 15 min were prepared, and their microstructure and corrosion resistance were characterized and analyzed. Results show that coating thickness and surface roughness increased with the extension of oxidation time. However, the samples showed the highest corrosion resistance when oxidation time was 5 min. This study shows that the reasonable regulation of micro-arc oxidation time is of great significance in the improvement of corrosion resistance of the biomedical magnesium alloy.

In this study, C_p/AZ91D composites are prepared through the composite casting process, and the influence of the C particle content and holding time on the microstructure and mechanical properties of the composites are studied. Results show that compared with the holding time, the grain refinement effect of C_p is more significant. When the mass fraction of addition C_p is 1.5% and the holding time is 15 min, the average grain size of the ingot cast in C_p/AZ91D composite material decreases from 176 to 32 μm, the overall fine and uniform structure enhances the uniform distribution of phase C particles in the composite matrix, and the highest hardness value reaches 89.07 HV.

LiFePO₄/Li₃V₂(PO₄)₃composite cathode materials with a series of mass ratios were synthesized using the liquid-phase co-precipitation method and carbon thermal-reduction process to improve the electronic conductivity of LiFePO₄ cathodes. X-ray diffraction, scanning electron microscopy, constant-current charge and discharge testing, and other analytical methods were used to analyze the phase composition, morphology, and electrochemical performance of the composites. When the mass ratio of LiFePO₄ and Li₃V₂(PO₄)₃ was 6:4, the composite exhibited regular morphology, higher crystallinity, and the best electrochemical performance: the discharge capacity was 148, 130.5, 121.5,and 112.3 mA·h·g-1 at rates of 0.1C, 1.0C, 2.0C, 5.0C, and 10.0C, respectively, and the capacity remained above 98.5% after 100 cycles at 1C. This effectively solves the problem of low conductivity of the LiFePO₄ material and will accelerate its application in power lithium-ion batteries.

This paper mainly discusses the optical properties of three different compounds CsPbBr₃, CsPb₂Br₅ and Cs₄PbBr₆，which exist stably in the whole inorganic perovskite materials in the Cs-Pb-Br ternary system. This study summarized and analyzed the preparation method, structural characteristics, and luminescence mechanism research. Among them, CsPb₂Br₅ and Cs₄PbBr₆ have large energy gap, but also have excellent fluorescence characteristics, the contradiction between theory and experimental conclusion has caused great controversy. It is expected to have more direct experimental data to determine the structure of the material, so the luminescence mechanism of Cs-Pb-Br ternary inorganic perovskite materials will be discovered.

The coated steel roller is subjected to bending moment and torque during operation. Under the effect of a small alternative load, the roller shaft prematurely experiences fatigue fracture failure, and the fracture mode is brittle fracture. The occurrence of fatigue fracture is a result of combined actions of several factors. The main factors are as follows: alternating cyclic stress; stress concentration at the root of the shaft caused by the change in shaft diameter; the change of microstructure in the welded joint region of steel roller caused by the fusion welding process ; the welding defects in weld joint region;surface state after welding. These factors lead to defects in welded joint region and surface of the components to become the origin of fatigue microcrack initiation. Existence of welding residual stress increases the average stress, which causes the weld defects to accelerate toward the inside of the adjacent shaft body and causes the roller shaft to prematurely experience fatigue fracture failure.

The teeth of a powder metallurgy gear were fractured during operation. A large number of globular iron-carbon compounds were found at the fracture site using SEM and EDS analysis, which indicates a weak bonding between powders resulting from an insufficient sintering temperature and duration of the original process. An improved sintering process and a new process of pressing, sintering, quenching, and low-temperature tempering were applied to Fe-1.8Ni-0.5Mo-1.2Cu-0.2C prealloyed powder. The pearlite quantity in the prepared gear is 60, and the new prepared gear comprises tempered martensite and ferrite subsequent to heat treatment. The impact toughness improved from 9.8 J/cm² to 15.2 J/cm².

Using standard stretch spline as the research object, the influence of gas counter pressure (GCP) and GCP holding time on melt-foaming behavior in chemical foaming injection molding (CFIM) process was investigated. Based on the results obtained from the experiment, the critical GCP pressure under which melt flow front cell was not cracking, the critical GCP pressure under which melt was not foaming, and the pressure release time of melt second foaming were proposed. Finally, the influence mechanism of GCP technology on melt foaming action during CFIM process was revealed.

This paper analyzes the chemical composition and structural characteristics of the fly ash in the Jining area, and how it could improve the performance of the anticorrosive coating of polyolefin adhesive tapes with a focus on the influence of the fly ash content on their mechanical properties. The experimental results show that the fly ash is mainly composed of SiO₂, Al₂O₃, and Fe₂O₃, the total mass fraction of which is approximately 88.04%. The mass fraction of CaO is 12.40%. The fly ash is an alkaline ash with a small amount of amorphous vitreous bodies and certain crystal minerals such as quartz, mullite, and hematite in it. Subsequent to adding fly ash, the mechanical properties of the anticorrosive coating of polyolefin adhesive tapes are improved. Subsequent to adding 15 batches of fly ash, the mechanical properties of the test sample are optimal with its tensile strength being 91.93 N/cm. Furthermore, the elongation at fracture is 536.67%, and the peel strength is 33.43 N/cm. Fly ash is an excellent filler that can replace calcium carbonate in the production of the anticorrosive coating of polyolefin adhesive tapes. The study can not only improve the utilization and added value of fly ash, improving the properties of the anticorrosive coating of polyolefin adhesive tapes, but it can also provide a theoretical basis for industrial applications of industrial fly ash in rubber reinforcement.

The hot filament chemical vapor deposition method was employed to optimize the preparation process of diamond films. Multilayer diamond films with uniform thickness were successfully prepared by altering their methane concentration, making it possible to prepare diamond films in various modulation cycles. The modulation cycle was as low as 100 nm .A stress analysis of single and multilayer diamond films was conducted using Raman spectroscopy and X-ray diffraction methods. It was found that the stress onmicrodiamond films in the single-layer structure was the highest, and would decrease as the size of diamond grains increased. In the multilayer structure of diamond films, the microlayer and nanolayers alternately grow in a uniform manner, which effectively reduces the stress on the films and improves their stability in applications.

Non-equilibrium plasma reaction can occur because different materials exhibit different properties;this increases the difficulty associated with the preparation of an overall protective coating.The objective of this experiment is to obtain an overall surface-protecting technology for the magnesium-aluminum connected parts.This study prepares an overall ceramic coating on the surface of the AZ31-7075 connected part based on the existing experimental consideration.Furthermore,deep analysis is applied to the specimens after 3,7,and 10 min of treatment.The results denote that the plasma oxidation sequence is related to the physical and chemical activities of different materials.The chemically active metal preferentially undergoes a ceramization reaction,which causes non-equilibrium growth of the ceramic coating.Preparing an overall ceramic coating for AZ31-7075 is of considerable significance to enrich the growth mechanism of the ceramic coating and the imbalanced growth mechanism of the connected parts of dissimilar metals.

Laser cleaning can effectively eliminate the impurities and oxides on a metal surface and improve the metal surface quality,exhibiting advantages of zero pollution,negligible damage to the substrate,and high cleaning efficiency.In this study,the application of laser cleaning to metal surface depainting and rust removal,tire mold cleaning,micromechanical cleaning,cultural relic protection,oil removal,and nuclear purification is reviewed.The main problems associated with this field are that the laser cleaning mechanism is not perfect and that the relation between the cleaning and damage thresholds is unclear for different materials.In the future,the cleaning mechanism of different materials should be improved,and the cleaning threshold should be clearly defined to achieve precise and efficient cleaning.

In view of the problem that it is impossible to grasp the macroscopic stereoscopic position when observing the failure fracture with scanning electron microscopy (SEM), the solutions were put forward by means of multiple three-dimensional (3D) techniques such as 3D microscope with super wide depth of field and 3D printing. Firstly, the fracture surface was imaged by 3D technology, and the 3D stereoscopic morphology of fracture surface was established. Then, the 3D model of the fracture surface was obtained by computer-aided technology. Finally, the model was used to assist scanning electron microscopy conduct the micro examination of the fracture surface. The results indicate that 3D technologies can be well applied in the field of failure analysis of metal parts.

In order to identify the effect of stress level and exposure duration on corrosion damage mechanical properties of 2219 aluminum alloy, some specimens exposed to EXCO corrosion solution under different stress levels and accelerated corrosion at different duration were selected to carry out surface pit depth measurement, mechanical properties testing and tensile fracture morphology observation. The test results show that both stress level and exposure duration are important factors affecting the development of stress corrosion damage thus affecting the change of mechanical properties of the material. At the initial stage of corrosion, i.e. before 1.5 h, the effect of stress level is limited. When the exposure duration reaches 2.0 h or more, the corrosion damage characterized by the average depth of pits caused by stress level is more significant. However, within the test time (2.5 h), the effect of stress level on corrosion damage is less than that of exposure duration, so the effect on the change of mechanical properties of materials is also less than that of exposure duration. Pits and microcracks caused by corrosion damage destroy the continuity of the material and decrease the mechanical properties of it, such as tensile strength, elongation and modulus of elasticity, which is an important reason for the instantaneous fracture of the material without sufficient plastic deformation stage in the tensile test. A larger pit or a deeper microcrack may be the origin of the main crack in the fracture surface.