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The production of nitrogen-doped carbon quantum dots (N-CDs) from walnut shell waste is crucially important for green chemistry and sustainable development. Herein we fabricate N-CDs by a bottom-up solvothermal method and use the novel N-CDs to modify the electron transport layer (ETL) in perovskite solar cells (PVSCs). The N-CDs can produce 440 nm fluorescence under the excitation of 350 nm light with a quantum yield of 8.75%. Infrared absorption spectra show that N-CDs contain high proportions of nitrogen-containing and oxygen-containing functional groups. , Through the incorporation of N-CDs into SnO2 ETL, the formation of defects is inhibited, and crystallinity is improved. This is because the N-CDs contains a large number of functional groups such as nitrogen and oxygen and these groups would interact with the ETL and perovskite, which reduce the defect/trap centers in PVSCs. Therefore, the N-CDs modified PVSCs show improved power conversion efficiency. This study provides a novel way to use walnut shell waste to synthesize N-CDs and achieve efficient and stable perovskites solar cells.

The effect of the inhomogeneity of the material properties on the quenching residual stress in the aluminum alloy was studied by using the finite element method simulation and the evolution of the quenching residual stress during the pre-stretching process was discussed in this paper. The results show that both the x-component and y-component of the quenching residual stresses in the non-uniform model are nearly overlapped with that in the uniform model. The effect of the inhomogeneity of the material properties on the quenching residual stress is negligible. After pre-stretching, the surface stress of the non-uniform model decreases from the middle line to the edge while the center stress increases. Contrastingly, both the surface and center stress of the uniform model are nearly stable along the same path, and the stress magnitudes are lower than that in the non-uniform model. The inhomogeneity of material properties mainly affects the pre-stretching residual stress distribution, while it has little effect on the quenching residual stress distribution.

Grain characteristics are one of the most important factors in determining alloy properties. Thermal deformation and solution treatment experiments were used to investigate the evolution of grain features and mechanical properties of Al-9.39 Zn-1.92 Mg-1.98 Cu alloy. The results reveal that when the deformation temperature rises, the recrystallized grain size, recrystallization fraction, and sub-grain size for the alloy's final microstructure gradually increase. The recrystallized grain size and fraction increase as the solution temperature rises, although the sub-grain size of the final microstructure of the corresponding alloy changes slightly. Fitting is used to deriving the function of recrystallization size, recrystallization fraction, and sub-grain size as a function of deformation temperature. The tensile properties of the alloy at T6 state are the best after deformation at 400°C and solution treatment at 470°C. The brittle fracture mode is shown in recrystallized grains, whereas the toughness fracture mode is shown in sub-grains.

The effect of Zn/Mg ratio on the as-cast microstructure and its evolution during homogenization of Al-Zn-Mg-Cu alloys was investigated by optical microscopy (OM), differential scanning calorimetry (DSC), scanning electron microscope (SEM) and X-ray diffraction (XRD). Experimental results showed that serious dendritic segregation existed in the as-cast microstructures while the second phases were mainly AlZnMgCu phase and Al2Cu phase. With the Zn/Mg ratio increasing from 1.5 to 2.0, the area fraction of AlZnMgCu phase decreased from 2.85% to 2.53%, which was attributed to the content of Mg element. Non-equilibrium eutectic phases dissolved into the matrix during homogenization and phase transformation from AlZnMgCu phase to Al2CuMg phase (S phase) was observed in low-Zn/Mg ratio alloy and mid-Zn/Mg ratio alloy. In the high Zn/Mg ratio alloy, the eutectic AlZnMgCu phase directly dissolved into the matrix during the homogenization, and no transformation from AlZnMgCu phase to S phase was found. A higher number of S phases appeared in low-Zn/Mg ratio alloy during homogenization treatment compared with mid-Zn/Mg ratio alloy with a regime of 465°C/24h. It could be inferred that low-Zn/Mg ratio alloys had a stronger phase transformation tendency from AlZnMgCu phase to S phase. Increasing the homogenization treatment temperature could impair the transition tendency from AlZnMgCu phase to S phase.

A new style of low temperature combustion cigarettes was prepared by implanting a thermally conductive cellulose/coper composite rod (TCCR) in the cut tobacco section, so as to explore the application feasibility at the low temperature environment. The burning temperature of the cigarettes was investigated by thermocouple to study the influence of the implanted TCCRs. The emission of conventional components and seven harmful components in mainstream smoke were also carried out to study the effect of TCCRs. The results show that implantation of TCCRs could reduce the burning temperature of cigarettes effectively, which decreased over 100 °C. In compared with conventional cigarettes, the amount of nicotine and nicotine-freed dry particulate matter (NFDPM) in mainstream smoke of TCCRs implanted cigarettes changed little, while the release of harmful components such as CO, HCN, NNK and phenol decreased over 20%. Moreover, the TCCRs, which made of copper paper with 2 g / 18 g weight ratio of pulp and copper, and 5 mm interval perforating, could reduce the burning temperature of cigarettes by 145 °C and the hazard index by 2.01.

To solve the problems of low strength and high viscosity of room temperature vulcanized liquid silicone rubber, a series of terminated vinyl silicone oil were designed and synthesized, and low viscosity and high strength silicone rubber were prepared by the mechanical reinforcing agent. the results show that the molecular structure of the vinyl-terminated silicone oil has a significant effect on the mechanical properties and viscosity of the silicone rubber, and the best performance is found when the content of vinyl-terminated silicone oil is 0.16%. The low viscosity and high strength silicone rubber prepared from it was reinforced by vinyl MQ resin and fumed silica, which had a significant effect on improving the performance. Its tensile strength increased to 5.03 MPa, elongation at break to 338.90%, and tear strength to 7.15 kN/m compared to conventional silicone rubber, while the hardness increased to 43°. The viscosity is 34.9 Pa•s. The compression modulus is 7.48 MPa.

The sandwich structure with foldcore is a new type of structural material with light weight, high specific strength, high specific rigidity and multi-functional potential, which is connected with each other in core space, this kind of three dimensional structures can be formed by folding based on two dimensional materials. The main research achievements and characteristics of sandwich structure with foldcore in recent years are summarized and analyzed according to the lightweight and multi-functional requirements of aircraft structure in this paper. The configuration optimization scheme and fabrication process of the sandwich structure with foldcore are described. Moreover, the research status of multi-function of the sandwich structure with foldcore are summarized, including sound insulation, thermal protection, stealth performance of the structure, etc.

AlSn20Cu alloy is currently one of the most widely used bearing materials, and its microstructure is the most important indicator in application. In this paper, AlSn20Cu alloy ingots were prepared by two methods: ordinary casting and semi-continuous casting, and deformation and annealing process of the two ingots were studied. Scanning electron microscope (SEM) and Image Pro Plus software were used to observe and analyze the evolution of the microstructure, and the morphological information such as the average grain size and area fraction of the Sn phase was quantitatively characterized. The effects of casting method, deformation temperature, deformation amount and annealing temperature on the morphology of Sn phase were studied in this paper. Compared with ordinary casting, the cooling rate of semi-continuous casting is higher, so the Sn phase is smaller, the casting defects are less, and the deformability of the alloy is better. The AlSn20Cu alloy prepared by ordinary casting has better deformability at about 140 °C, while the AlSn20Cu alloy prepared by semi-continuous casting can be rolled and deformed at room temperature. When the deformation is greater than 40%, after annealing at 250 °C, the average grain size of the Sn phase in the AlSn20Cu alloy prepared by semi-continuous casting is around one hundred square microns and the area fraction is more than 10%, and the Sn phase morphology is better than ordinary casting alloy under any processing conditions.

Effects of different solution treatments on microstructure, texture and mechanical properties of 6A16 aluminum alloy sheet were investigated by electron back-scattered diffraction (EBSD) and tensile test. The results show that among the five solution treatments, with the increase of solution temperature and solution time, the average grain size increases and the yield strength of the alloy sheet gradually increases. The maximum elongation at break of the sheet is at 545 °C, and it increases with the increase of solution time. Therefore, the mechanical properties of the sheet are the best when the solution treatment is 545 °C for 5 min.

The second phase dissolution of Al-9.2Zn-2.0Mg-1.9Cu alloy conducted by various temperatures of 2h was researched with the help of optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), electrical conductivity and differential scanning calorimetry (DSC) analysis. The results gave rise to the second phase existence of Mg(Zn,Cu,Al)2 and Fe-containing phases in the as-extruded alloy. When the alloy solution treated with a temperature varied from 450°C to 470°C, a small quantity of Mg(Zn,Cu,Al)2 phase still existed in the alloy while its content exhibited a decrement trend with the solution temperature rose. For the alloy solution treated at a temperature of 475°C, Mg(Zn,Cu,Al)2 phase dissolved into the matrix completely while Fe-containing phase still remained. The electrical conductivity of quenched alloy decrease with the solution temperature increase and reached a minimum value at 470°C, and then rose slightly for the solution temperature of 475°C.

Perforated structure is the mechanical weak link of polymer-bonded explosive (PBX). Improving its mechanical property may promote the reliability and effectiveness of weapon system. In this study, strengthening of the perforated PBX plate is conducted by employing surface coating. Digital image correlation (DIC) analysis results suggest that the regional applied epoxy coating layer is able to improve the mechanical properties of the plate. By confining the deformation and releasing the stress concentration around the perforation, the coating layer enhances the load carrying ability and energy dissipation capacity of the plate significantly. This investigation may provide a convenient and effective structure modification method for energetic material, and at the same time, lay foundation to the performance optimization of weapon system.

In recent years, with the urgent need of the country to vigorously promote the transformation and upgrading of the construction industry and the modernization of the construction industry, it has been proposed to vigorously develop prefabricated buildings and increase the proportion of prefabricated buildings in new buildings. The prefabricated concrete building is a concrete structure with prefabricated components in the factory and processing and connection on the construction site. Because of its fast construction speed and good overall benefits, it is widely promoted. For prefabricated buildings, the key technology is the connection of structural nodes, and most of the component connections use concrete sleeve connections. The quality of the sleeve grouting material is very important. The basic formula of the grouting material leads to different and different mechanical properties. Conditions apply. This article starts with different sleeve grouting patents, summarizes different functions and characteristics, and provides a reference for the next development of sleeve grouting.

Second phase dissolution of Al-Zn-Mg-Cu alloys during solution treatment was closely associated with the content of main alloying elements. In present work, the phase characteristics of several Al-Zn-Mg-Cu alloys with various main alloying contents were investigated, and the second phase dissolution of these alloys during solution treatment was analyzed. The results showed that the extrusion alloys possessed abundant second phases, mainly including Mg(Zn,Cu,Al)2 phase and Fe-rich particles. The DSC analysis proved that the larger endothermic peak corresponded to the alloy with larger main alloying content, and the XRD spectrogram also backed up the advantage of Mg(Zn,Cu,Al)2 phase. After solution treated at 450°C, the residual phases remained in the alloys and the quantity of them were positively correlated with the main alloying content. With the increase of solution temperature, the electrical conductivity of the alloys showed a decremental trend, while the alloys with relatively low main alloying contents exhibited an inversion at the solution temperature of 475°C. The SEM observation demonstrated that no Mg(Zn,Cu,Al)2 phase was observed in the alloys with relatively low main alloying contents while seldom still remained in the alloy with high main alloying content after solution treated at 470°C. After solution treated at 475°C, Mg(Zn,Cu,Al)2 phase completely dissolved into the matrix for the alloy with high main alloying content. The statistics of residual phase quantity also proved this.

Earphones are often exported to foreign countries by sea as consumer goods. In view of the humid marine environment, the earphone packaging box is often placed with anti-mold chips to prevent mold, while the volatilization of the anti-mold chips will also cause corrosion problems. In this study, a large number of aluminum earphone connectors were corroded in the process of ocean transportation, and the corrosion products were located in the left earphone connector close to the anti-mold chips. It’s determined that sulfate and nitrate ions lead to the corrosion of the aluminum connectors, and these are the volatilization products of the anti-mold chips. This conclusion was further confirmed by the simulation test, which was carried out on the anti-mold chips and aluminum connectors at 85 °C, 85% RH humidity for 72 h. The aluminum connectors were obviously corroded, and the morphology and composition of the corrosion products were the same as those on the actual earphones. The corrosion was successfully prevented by a PTFE coating on the surface of aluminum connectors. Keywords: Earphones; Anti-mold chip; Aluminum; Corrosion; PTFE coating

Both microstructure inhomogeneity and mechanical property diversity along the thickness direction in rolled thick aluminum plates have been considered to have a remarkable impact on the performance and properties of the products made from the plates. In this study, scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD) characterizations of microstructure and texture types along the thickness directions of Al7055 thick plate specimens prepared using two conditions, hot-rolling and solution-quenching, were performed. To examine the mechanical properties, uniaxial tensile tests were also carried out on specimens machined from both types of thick plates, using a layered strategy along the thickness direction. The results indicate that both the microstructure and mechanical properties are inhomogeneous under the two conditions. Furthermore, it is evident that there is a hereditary relationship between the mechanical properties of the two plates—areas with higher yield strength in the as-hot-rolled plate correspond to areas with the higher yield strength in the as-solution-quenched plate

The fatigue crack growth of Al-Zn-Mg-Cu alloy can be adjusted by different aging treatments. In the present work, a high Zn-containing Al-Zn-Mg-Cu alloy was treated by single, double and triple stage aging treatments and typical T6, T79 and T77 states were selected by tensile properties. Fatigue crack growth under these aging states was tested and related fracture morphology and precipitation characteristics were observed. The results showed that fatigue crack growth resistance for the alloy was T6

As product structure becomes more and more complex, the fault mode presents a diversified trend, and it is more difficult to determine the causes of system failure for a complex product. The main objective of this study is to provide an effective failure analysis method based on the combination of fault trees analysis (FTA) and generalized grey relation analysis (GGRA) for complex product. In this method, the product system failure is defined and the fault tree is constructed by FTA methodology firstly; and then GGRA is employed to identify the correlations between each fault mode and the system failure; finally, the main causes of system failure are identified and the corresponding measures can be made. A case study of a WD615 Steyr engine is conducted throughout the text to verify the validity of this method. The present study would help facilitate the failure and reliability analysis for complex product and benefit designers for the product improvement.

A 100 kW solid target was successfully developed for the CSNS phase one. Tungsten was selected as the CSNS target material and a layer of tantalum with a thickness of only 0.3mm as a protective layer. Eleven target blocks were fixed in parallel in a stainless steel target container with 1.2mm gap between each block. Using a specially designed spreader, the target plug can be easily replaced. The parameters of the target were stable and normal in the course of more than a year of operation, the temperature rise of the target cooling water inlet and outlet increased as the proton beam power increased.

Intermediate annealing on anisotropy and mechanical properties of an Al-0.78Mg-0.90Si-0.65Zn-0.16Cu (wt. %) alloy was investigated by tensile test, optical microscope (OM) and electron back-scattered diffraction (EBSD). The results indicated that alloy sheet displayed various microstructure after without intermediate annealing, intermediate annealing treatment at 350°C for 2 h, 450°C for 2 h and 500°C for 5 min. Compared with the alloy without intermediate annealing, the alloy exhibited equiaxed grain with 35.0µm after annealing at 500°C for 5 min, grain orientation of the alloy was distributed randomly, and plastic strain ratio value of 45° direction was more than 0.6. The anisotropy of the sheet was significantly reduced. Annealing at 500°C for 5 min was suitable for the production process of automobile body sheets.

In order to analyze aging behavior of an Al-8.0Zn-1.8Mg-2.0Cu alloy, the microstructure of the alloy subjected to T6 and T76 states are investigated by transmission electron microscopy (TEM) and high-resolution electron microscopy (HREM). Based on the precipitate observations, precipitate size distributions and average precipitate size are extracted from bright-field TEM images projected along 〈110〉Alorientation with the aid of an imaging analysis. The results indicate that the main precipitates are GPI zone, GPII zone and η' phase in the T6 alloy while η' phase and η phase in the T76 alloy. The bright-field TEM observations reveal that the matrix precipitates for the T6 alloy have small size and dispersive distribution while that for the T76 alloy has big size and sparse distribution. Both have discontinuously distributed grain boundary precipitates. Quantitative structural information including precipitate size distribution and average precipitate size has been calculated by an image analysis based on the bright-field TEM images projected along 〈110〉Alorientation. The results show that the T6 alloy has a narrower precipitate size range than the T76 alloy and thus the T6 alloy possesses a smaller average precipitate size than the T76 alloy.

Aging treatments of an Al-9.0Zn-2.0Mg-2.0Cu alloy, which belongs to high strength aluminum alloy widely used in aerospace industry, are investigated by various techniques, including hardness, electrical conductivity, mechanical properties, transmission electron microscopy (TEM) and high-resolution electron microscopy (HREM). The result shows that hardness and conductivity for one-step aging treatment increase with aging time prolongs while those for two-step aging treatment exhibit increment and decrement, respectively. Besides, the ultimate tensile strength (UTS) and yield strength (YS) for one-step and two-step aging treatments show slow increase and obvious decrease, respectively. Based on these, typical T6 and T76 aging regimes are extracted for microstructure observation. The matrix precipitates for the T6 alloy have small size and dispersive distribution while that for the T76 alloy has big size and sparse distribution. The grain boundary precipitates for both exhibit discontinuous distribution and the T76 alloy has larger size and broader precipitate free zones. The selected area diffraction patterns and HREM observations reveal that main precipitates for the T6 alloy are GPI zone, GPII zone and η' phase while for the T76 alloy are η' phase and η phase.

Effect of multi-section linear non-uniform heat transfer coefficient on quenching residual stress distribution in 27mm-thick Al-Zn-Mg-Cu aluminum alloy plate was simulation studied by using the finite element method, and the surface quenching residual stress distribution was measured by the X-ray diffraction method and hole-drilling method. The results show that the surface quenching residual stress represents the same distribution with non-uniform heat transfer coefficient in the transverse direction and the stress level maintains initial stress level of the heat transfer coefficient at each location. The distribution of the quenching residual stress in the center of the plate is approximately uniform and the stress level is approximately equal to average of maximum and minimum initial stress level. The measured surface quenching residual stress shows a wavy distribution in the transverse direction, which is similar to the simulated surface stress distribution without considering the stress level. The measurement results can be explained by the multi-section linear non-uniform quenching model.

The manufacturing accuracy of the guide structure of the PWR control rod drive line (abbreviated as the drive line) is very important to ensure the accurate performance of the function of the drive line. In this paper, the technology of high speed laser welding is studied, and the parameters of low stress and high speed laser welding are obtained. The heat source of laser welding, the shrinkage of laser welding weld and the welding deformation of laser welding are modeled and analyzed. The deformation simulation technology of laser welding of driving line guide structure is established to provide theoretical guidance for the manufacture of laser welding of this part. The specific contents include: laser welding test and thermal cycle test, macroscopic weld forming, residual stress test, heat source model establishment and parameter determination, laser welding weld shrinkage model establishment and welding deformation prediction. Finally, the driving line guide structure welded by high speed laser uses Φ 10.26mm bar drop gauge at the speed of 4 × 5 m / min to pass freely at 0 °, 90 °, 180 °and 270 °, and the friction force is less than 88N. The drop bar gauge of Φ10.26 mm is used to pass freely through the driving line guide structure welded by high speed laser at the speed of 4 ~5 m/min at 0 °, 90°, 180° and 270°, and the friction force is less than 88N.

This paper presents an experimental study to investigate the effects of compressive stress during the CO2 attack on wellbore cement under carbon capture and storage (CCS) conditions. Oil well cement samples were designed to be exposed to humid supercritical CO2 gas and CO2-saturated brine and simultaneously subjected to external compressive stresses with load levels of 0, 25%, 50%, and 75% of the ultimate compressive strength. Morphology changes were determined using phenolphthalein dye testing and scanning electron microscopy. Mineral changes were detected by X-ray diffraction. Relative compressive strength and gas permeability of exposed cement were analyzed. It is shown that the 25% stress level has little effect on degradation of cement while the applied compression load up to 50% increased the compactness of cement and finally slowed down the degradation rate. In contrast, a much higher compressive stress level up to 75% facilitated the generation and propagation of micro-cracks. The stress induced micro-crack finally caused a surge in CO2-rich fluids and then significantly accelerated the degradation rate of oil well cement. Findings from this study expanded the understanding of the integrity of oil well cement for CCS wells.

Electromagnetic shielding materials are widely used in engineering. Shielding effectiveness is an important index to measure the shielding effect of electromagnetic shielding materials. A method for calculating the shielding effectiveness of electromagnetic shielding materials is discussed in this paper. This method applies the small reflection theory in transmission line theory. Two kinds of materials are selected as samples. Firstly, the shielding performance is calculated by calculation. Then, shielding performance was measured using a network analyzer and coaxial devices. By comparing the above two results, the feasibility of this method is verified. By using this method, the shielding performance with acceptable accuracy can be obtained when the electromagnetic parameters of the material are known. Thus, the limitation for the application of electromagnetic shielding materials is reduced.

It was found that the addition of MnO2 particles into the HF/HNO3/H2O system could significantly improve the texturization etching performance on multi-crystalline silicon (mc-Si) wafer. For a wide component ratio range of HF/HNO3/H2O from HF-rich to HNO3-rich, by optimizing the MnO2 usage and the etching time, the addition of MnO2 particles always reduced the texture reflectance greatly. Low weighted average surface reflectance (Ra) for the AM1.5G sun spectrum in the wavelength range of 380–1100 nm was achieved on both the slurry wire sliced (SWS) mc-Si and the diamond wire sliced (DWS) mc-Si. Due to its excellent effect and simple processing, the MnO2/HF/HNO3/H2O etching system can be expected as a candidate for high-performance texturization on mc-Si wafer, especially on DWS mc-Si wafer.

Pressurizer surge line is one of the key equipments of nuclear power plants. The thermal stratification due to the intersection of hot and cold fluids inside the pressurizer surge line may affect the safe operation of nuclear power plant. In order to investigate the stress distribution and fatigue characteristics of surge line subjected to long-term thermal stratified loadings, a mechanical model of the surge line was established. And then, according to different temperature distribution assumptions, thermal stress analysis and fatigue assessment were conducted. The results show that the maximum stress appears under the load condition with maximum temperature difference, and finer temperature distribution can obtain more accurate stress and displacement results. The maximum value of fatigue cumulative coefficient appears at the junction of straight pipe and elbow with large temperature difference.

In the chemical vapor deposited zinc sulfide, it often appears obvious light and dark growth bands along the growth direction, which will affect the homogeneity of optical properties of CVD ZnS and the efficiency of subsequent heat treatment. X-ray diffraction, Metallographic microscope and SEM were used to detect the crystal structure, grain size and microstructure, and the concentration of Zn and S in different bands was tested by EDTA titration, XRF, ICP and HF-combustion IR absorption spectrometric method. Results: Compared to the normal band, the grain size in the bright band was significantly larger, and the concentration of hexagonal phase in the bright band was lower, while the concentration ratio of Zn and S in the CVD ZnS did not have the regularity in the different bands. Combining with relevant knowledge about characteristics of the deposition process and crystal growth theory, the paper analyzes the formation mechanism of growth bands in CVD ZnS, and find that the main factor is the mutation of the concentration of the reactants in the deposition surface, affect the crystal nucleation rate and growth rate, eventually lead to the different grain morphologies, and even showing up the macroscopic growth bands. Compared with the actual process parameters, we have confirmed it and found out the main causes of mutation of the reactant concentration, this will have important guiding significance to the improvement of product quality in the future.

A Zn-added Al-Mg-Si-Cu alloy during aging at 170 °C up to 34 h exhibits an interesting age-hardening effect. Small clusters, enriched in Mg and Si, are present in the sample after 0.25 h aging. The β′′ phase is dominant with the peak hardness of 135 HV after aging of 8 h. A decrease in hardness of the alloy occurs with the aging time increasing to 34 h, due to the coarsening of β′′ phase. It is also found that the Cu-containing L phase co-exists with the β′′ phase at this aging condition. The quantitative solute concentrations of the matrix show that the formation of clusters is consistent with the slight lower contents of Mg, Si and Cu compared with the alloy chemical composition, and the present of β′′ and L phase is associated with the further partitioning of Mg, Si and Cu from the Al matrix into the precipitates. No Zn-rich clusters and precipitates are observed and the Zn concentration in matrix has no significant change during aging for up to 34 h. This result means that the major of Zn remains in the matrix as aging continues.