Achieving strong interfacial bonding of CFRP and magnesium alloy by modifying magnesium alloy surface via alkaline etching with EDTA addition

The interfacial properties of fibre metal laminates are closely related to the surface microstructure of metals. Herein, a hitherto unreported honeycomb-like micro/nano-porous structure was successfully fabricated on an AZ31B Mg alloy surface by incorporation of ethylenediaminetetraacetic acid disodium (EDTA-2Na) into an alkaline solution and achieved excellent interfacial bonding property between AZ31B and carbon fibre-reinforced plastic. The addition of EDTA-2Na can promote the formation of etched pores. The growing nano-scale etched pores join together to produce micro-scale pores and ultimately lead to the formation of a micro/nano-porous structure. The 60 min etched AZ31B/carbon fibre-reinforced plastic laminate exhibits a bonding strength of 25.87 MPa, which is an increase of 350.7% compared to that of the untreated sample. The significant increase in bonding strength is mostly ascribed to composite mechanical interlocking by the micro/nano-porous structure and chemical bonding through the formation of MgCO3 and MgO1+X. In addition, the characteristics of micro-pores also affect the bonding strength

Wear and corrosion properties of HVOF sprayed WC-Cr3C2 composite coating for application in polysilicon cyclone separator

The wear and corrosion properties of the cyclone separator play a crucial role for the preparation of high-purity trichlorosilane in the Siemens method polysilicon cold hydrogenation system. In this work, we used fluent simulation technology to determine the optimal spraying process parameters of high velocity oxy-fuel (HVOF) technology, and the Ni60-WC composite coatings with different content of Cr3C2 were prepared on 316L stainless steel surface by using HVOF technology. The microstructure, phase structure and mechanical properties of the coating were characterized, and the wear resistance and corrosion resistance of the coating were studied. By comparing the friction coefficient, wear rate, wear profile and electrochemical polarization and impedance spectrum of the coating, the effects of Cr3C2 content on the microstructure, hardness, wear resistance and corrosion resistance of HVOF sprayed WC composite coating were studied. The results show that the coating prepared by using the simulation parameters are uniform and compact, the coating is tightly bonded to the substrate. The main phases in the coating are WC, W2C and Cr3C2. With the increase of Cr3C2 hard phase, the wear resistance and corrosion resistance gradually improve. Ni60–35WC–20Cr3C2 and Ni60–35WC–30Cr3C2 volume loss rate is the lowest, the friction depth is the shiniest, compared with the substrate, the wear rate is reduced by more than 95 %. Ni60–35WC–20Cr3C2 has the highest corrosion potential, the smallest corrosion current, the smallest corrosion rate and the largest impedance spectrum radius. However, when the content of Cr3C2 reaches 30 %, the corrosion resistance is the worst. Combined with wear resistance and corrosion resistance analysis, the Ni60–35WC–20Cr3C2 coating is selected to provide support for upgrading and prolongating the service life of the cyclone separator

Corrosion mechanism and performance of Cr-coated Zr-4 alloy in 360 °C water and 1300 °C steam

A dense and uniform Cr coating is prepared on the Zr-4 alloy using multi-arc ion plating technology, with the aim of serving as an accident-tolerant fuel cladding for light water reactors. The corrosion performance of Cr-coated Zr-4 alloy is investigated after exposure to 360 °C and 18.6 MPa corrosion conditions for up to 5040 h, and its corrosion mechanism is discussed. Furthermore, the oxidation behavior of the Cr-coated Zr-4 alloy in steam at 1300 °C is mainly examined. It is observed that the ZrO2 channel within the Cr coating acts as an oxygen diffusion path during steam oxidation and facilitates the reduction of Cr2O3 by providing Zr. When the ZrO2 channel diffuses to the Cr2O3/Cr interface, Cr2O3 is reduced to form ZrO2 and Cr. When the thickness of the Cr2O3 layer is minimized, the Cr coating fails. The in-situ oxidation of the Cr2Zr layer results in the formation of ZrO2 and Cr2O3, while the substrate beneath the Cr coating is oxidized to form a ZrO2 layer. The whole oxidation process of the Cr-coated Zr-4 alloy up to 1300 °C is presented in detail

Ecological Security Patterns at Different Spatial Scales on the Loess Plateau

The study of ecological security patterns (ESPs) is of great significance for improving the value of ecosystem services and promoting both ecological protection and high-quality socio-economic development. As an important part of the “Loss Plateau-Sichuan-Yunnan Ecological Barrier” and “Northern Sand Control Belt” in the national security strategic pattern, there is an urgent need to study the ESPs on the Loess Plateau. Based on a remote sensing dataset, this study identified the ESPs at different spatial scales, and analyzed the similarities and differences of ecological sources, corridors, and key strategic points, so as to better inform the development and implantation of macro and micro ecological protection strategies. When taken as a whole unit, we identified 58 ecological sources (areas with higher levels of ecosystem services) on the Loess Plateau (total area of 57,948.48 km2), along with 134 corridors (total length of 14,094.32 km), 1325 pinch points (total area of 315.01 km2), and 2406 barrier points (total area of 382.50 km2). When splits into ecoregions, we identified 108 sources (total area of 67,892.51 km2), 226 corridors (total length of 13,403.49 km), 2801 pinch points (total area of 851.07 km2, and 3657 barrier points (total area of 800.70 km2). Human activities and land use types are the main factors influencing the number and spatial distribution of corridors, ecological pinch points, and barrier points. ESPs constructed at different spatial scales are broadly similar, but significant differences among details were identified. As such, when formulating ecological protection and restoration strategies, the spatial scale should be considered. Moreover, specific programs should be determined based on ESP characteristics to maximize the protection of biodiversity and ecosystem integrity from multiple perspectives and directions

Ag₂S-Decorated One-Dimensional CdS Nanorods for Rapid Detection and Effective Discrimination of n-Butanol

N-butanol (C4H9OH) is a volatile organic compound (VOC) that is susceptible to industrial explosions. It has become imperative to develop n-butanol sensors with high selectivity and fast response and recovery kinetics. CdS/Ag2S composite nanomaterials were designed and prepared by the solvothermal method. The incorporation of Ag2S engendered a notable augmentation in specific surface area and a consequential narrow band gap. The CdS/Ag2S-based sensor with 3% molar ratio of Ag2S, operating at 200 °C, demonstrated a remarkably elevated response (S = Ra/Rg = 24.5) when exposed to 100 ppm n-butanol, surpassing the pristine CdS by a factor of approximately four. Furthermore, this sensor exhibited notably shortened response and recovery times, at a mere 4 s and 1 s, respectively. These improvements were ascribed to the one-dimensional single-crystal nanorod structure of CdS, which provided an effective path for expedited electron transport along its axial dimension. Additionally, the electron and chemical sensitization effects resulting from the modification with precious metal sulfides Ag2S were the primary reasons for enhancing the sensor response. This work can contribute to mitigating the safety risks associated with the use of n-butanol in industrial processes

Effect of annealing on corrosion resistance and mechanical properties of Cr–Fe–Ni–Co–Mo–Si–B amorphous coating

Cr–Fe–Ni–Co–Mo–Si–B amorphous coating was successfully prepared on 316 L steel using atmospheric plasma spraying (APS). The effects of different annealing temperatures on the crystallization process of amorphous coatings, thus on the corrosion resistance and mechanical properties of coatings were studied. The results indicated that heat treatment can increase the hardness of the amorphous coating by 12.5% and reduce the wear rate by 30%. In addition, compared to heat-treated coatings, the amorphous coating had the highest corrosion voltage (−0.506V) and lower corrosion current (5.609 × 10−6 A). The passivation film on the amorphous coating provided the best protection due to the relatively high content of Cr2O3. The molecular dynamics (MD) calculation results also indicated that the adsorption energy of hydrogen chloride molecules on Cr–Fe–Ni–Co–Mo–Si–B amorphous coating (−90.94 kcal/mol) was greater than that of 316 L (−293.03 kcal/mol)