[Objective] 6061 aluminum alloy is widely used because of its good comprehensive properties. However, the quality of its welded joints generally has certain limitations. This study aims to effectively improve the quality of 6061 aluminum alloy welded joints by using the method of laser shock peening, deeply explore the changes of mechanical properties and microstructure of welded joints before and after laser shock peening, and analyze the internal influence mechanisms, so as to provide a solid theoretical basis and practical guidance for the optimization of aluminum alloy welding process. [Methods] A 6061 aluminum alloy welded joint was selected as the research object, and its surface was treated by laser shock peening technology. In the process of treatment, the parameters of laser frequency, shock range, pulse width, and overlap rate of laser pulses were strictly controlled. The influence of laser energy on 6061 aluminum alloy welded joints was studied. The mechanical properties of welded joints before and after laser shock peening were analyzed, such as tensile strength and hardness. At the same time, the changes of microstructure characteristics such as grain size and shock layer thickness at the weld were observed and compared by means of microstructure analysis technologies, including optical microscopy, scanning electron microscopy, and electron backscatter diffraction (EBSD). [Results] First of all, in terms of the relationship between laser energy and tensile strength of welded joints, there is a clear positive correlation. Specifically, with the gradual increase in laser energy, the tensile strength of welded joints also increases steadily. Secondly, the detection of the hardness of the weld surface shows that the hardness is significantly improved after laser shock peening, and the increase is about 23％. Finally, from the microstructure point of view, the thickness of the laser shock layer changes significantly, greatly increasing from the initial 15.83μm to 30.77μm, which indicates that the laser shock has a deep impact on the surface of the material. At the same time, the grain size of the weld center also changes significantly, decreasing from the original 33.68 μm to 14.5 μm. The grains obviously become finer, namely that the microstructure is optimized. [Conclusion] Based on the above research results, it can be concluded that laser shock peening technology shows excellent effect in the treatment of 6061 aluminum alloy welded joints. The high energy generated on the surface of metal materials can effectively reduce the adverse effects of plastic deformation on the surface and interior of materials and promote grain refinement, which is the key factor to improve the mechanical properties of welded joints. Through laser shock peening, the tensile strength and hardness of welded joints are effectively improved, which not only helps to improve the reliability and durability of 6061 aluminum alloy welded structures in practical applications but also provides strong technical support for further expanding the application range of aluminum alloys in high-end manufacturing. In the future, the optimal process parameter combination of laser shock peening can be further studied in order to improve the quality of 6061 aluminum alloy welded joints more accurately and efficiently and promote the continuous development and innovation of aluminum alloy welding technology.

[Objective] In the context of the rapid development of world industrialization, the indiscriminate discharge of dye wastewater poses a threat to the ecological environment and human life. Therefore, seeking an efficient, clean, and economical wastewater treatment method has become a research hotspot. In recent years, a photo-Fenton catalytic technology has shown great advantages in treating organic dye wastewater. BiOBr is a photocatalyst with a good visible light response, a strong light stability, and a layered structure. However, it has the problem of easy recombination of photogenerated electron-hole pairs. Monometallic irons such as Fe₂O₃, Fe₃O₄, FeOOH, and nanoscale zerovalent iron exhibit excellent performance in Fenton catalytic activity. Furthermore, their photo-Fenton catalytic activity has also been acknowledged. [Methods] Coupling BiOBr with iron-based oxides with a good Fenton catalytic activity or modifying BiOBr can effectively improve the treatment efficiency of organic wastewater. To further improve the efficiency of photo-Fenton catalytic technology in treating organic pollutants in water, a Fe₂O₃/BiOBr composite photo-Fenton catalyst with a Z-scheme heterojunction was prepared by precipitation and calcination methods. The composite catalyst was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), and the photo-Fenton catalytic activity and mechanism of the composite catalyst were studied using Rhodamine B (RhB) as an organic pollutant model. [Results] The results indicate that the Fe₂O₃/BiOBr composite photo-Fenton catalysts all exhibit excellent photo-Fenton catalytic activities compared to the individual catalysts, and the 1.2％ Fe₂O₃/BiOBr has the highest photo-Fenton catalytic activity (99.59％, 60 min), which is about 24.8 and 3.6 times higher than those of pure Fe₂O₃ and BiOBr, respectively. Electrochemical testing and the radical trapping experiment show that the 1electrons in the composite catalyst flow from the conduction band of BiOBr to the valence band of Fe₂O₃. This achieves effective separation of photogenerated electron-hole pairs and promotes the regeneration of Fe²⁺, thereby improving the photo-Fenton catalytic efficiency of the composite catalyst. [Conclusion] The composite catalyst 1.2％Fe₂O₃/BiOBr achieves complete degradation of the organic pollutant in all five cycles of the catalytic degradation experiments with no decrease in catalytic degradation efficiency. This demonstrates that the composite catalyst possesses excellent catalytic activity and stability, which makes it a promising candidate for application as a photo-Fenton catalyst in green, economical, and efficient industrial wastewater treatment processes.

[Objective] In recent years, the development of lithium-ion batteries have encountered bottlenecks such as slow energy density improvement, high cost and narrow temperature adaptation range. Potassium-ion batteries featuring low cost and high energy density have become the ideal choice for the next generation of large-scale electrochemical energy storage systems. Phosphate fluoride (KVPO₄F) serves as the first-choice cathode material for potassium-ion batteries due to its solid three-dimensional framework and high operating voltage. However, the repeated embedding/removal of large potassium ions in the charge and discharge process will cause structural pulverization to KVPO₄F, resulting in rapid capacity decay and poor cyclical stability. Moreover, the structure formed by the covalent bond of the coordination polyhedron restricts the electron transfer mode, greatly hindering the dynamics performance of KVPO₄F cathode material, and resulting in poor magnification behavior and low actual capacity. The modification of KVPO₄F material is usually studied by such strategies as element doping, carbon coating, and morphology engineering to improve the capacity, magnification and cyclical stability of KVPO₄F cathode material, and thus enhance the potassium storage performance. However, due to the imbalance between lattice spacing, crystal face exposure and V³⁺ content, the capacity, magnification, and cyclical stability are difficult to be improved simultaneously. The synthesis of KVPO₄F cathode material usually consists of two successive heat treatment steps, including the preparation of the VPO₄ precursor and the secondary calcination of VPO₄ mixed with KF to produce KVPO₄F. Therefore, the crystal structure of VPO₄ is bound to affect the particle size and crystal face orientation of KVPO₄F, thus affecting the potassium storage stability of KVPO₄F. [Methods] A series of VPO₄ materials were prepared by the sol-gel and high-temperature annealing method, and the effects of different VPO₄ materials on the lattice and electrochemical properties of the final product KVPO₄F were studied. [Results] The results show that VPO₄ prepared at different temperatures can significantly affect the lattice exposure intensity, lattice spacing and V³⁺ content of KVPO₄F. As the temperature rises from 700℃ to 800℃, the lattice exposure intensity, lattice spacing and V³⁺ content increase first and then decrease. When VPO₄ annealed at 750℃ is employed as the precursor, the prepared KVPO₄F has the most intense lattice plane exposure, the largest lattice spacing and the highest V³⁺ content, which ensures excellent structural stability, ion migration and ion storage quantity during the charge and discharge process. The electrochemical property test shows that after 30 cycles at 0.2 C (1 C=131 mA/g), the specific capacity of KVPO₄F is 57.3 mAh/g, much higher than that of the control sample under the same conditions. Additionally, the reversible specific capacity of KVPO₄F at 0.2 C, 0.5 C, 1 C, and 2 C is 62.1, 53.8, 44.6, and 30.6mAh/g, respectively. [Conclusion] Based on VPO₄ regulation, this study determines the effect of precursor VPO₄ on the microstructure of the final product KVPO₄F, and reveals the internal mechanism of improving electrochemical properties, laying a sound foundation for obtaining high-capacity KVPO₄F cathode material.

[Objective] The anisotropy and isotropy of thermal transport are fundamental properties of materials, which are crucial in practical applications. However, current research on tuning the transition from anisotropic to isotropic thermal transport primarily relies on structural design or material processing. The methods are time-consuming, costly, and irreversible, which severely limits flexibility of the properties in practical applications. Therefore, a scheme was proposed to regulate the thermal transport properties of two-dimensional borophene by using an external electric field, aiming to explore a new method for stable and reversible regulation without altering the atomic structure of the material. [Methods] First-principles calculations were combined with the phonon Boltzmann transport equation to systematically investigate the effect of an external electric field on the thermal transport properties of borophene. The underlying physical mechanisms were revealed systematically by quantifying the regulatory effects of electric field strength on phonon lifetime, thermal conductivity, and anisotropy, and the ratio of thermal conductivities in two in-plane directions (x and y directions) was used as an indicator of the changes in anisotropy. [Results] Under the influence of an external electric field, the lattice thermal conductivity of borophene in both in-plane directions increases significantly and gradually peaks with a maximum enhancement factor of 2.82. Meanwhile, the intrinsic anisotropy ratio is boosted to a maximum value of 2.13. As the electric field strength increases further, the thermal conductivity drops rapidly, and the anisotropy exhibits oscillating decay. When the electric field strength increases to 0.4 V/Å, the thermal conductivity is dramatically reduced. Nearly isotropic thermal transport characteristics are demonstrated when the anisotropy ratio decreases to 1.25. Further analysis reveals that this abnormal transition from anisotropic to isotropic thermal transport is fundamentally due to the large enhancement and suppression of phonon lifetime at moderate and high electric field strengths, respectively, which acts as an amplifying or reducing factor for thermal conductivity. [Conclusion] Phonon lifetime can be modulated by an external electric field, achieving stable and reversible precise regulation of the thermal transport properties of two-dimensional borophene without altering its atomic structure. This approach effectively overcomes the limitations of traditional regulation methods and provides a new theoretical and technical pathway for the precise regulation of phonon thermal transport anisotropy, showing a broad application prospect in such fields as thermal management of nanoelectronics and thermoelectric energy conversion.

[Objective] Cracks in aero-engine turbine guide vanes are typically repaired using wide-gap brazing. However, pores usually appear during the formation of wide-gap brazed joints, which can lead to a decline in their high-temperature mechanical properties. To suppress the formation of pores, a certain pressure is applied during brazing. Nevertheless, the effects of brazing pressure on the microstructure and mechanical properties of wide-gap brazed joints remain unclear. [Methods] In this study, wide-gap brazed joints were prepared under different brazing pressures. The effects of brazing pressure on the microstructure and mechanical properties of the joints were investigated through tensile testing, microhardness characterization, fracture morphology observation, energy dispersive spectroscopy (EDS) analysis, and X-ray diffraction (XRD). [Results] The experimental results show that at a constant brazing temperature, the tensile strengths of the wide-gap brazed joints under brazing pressures of 10, 20, and 50 kg with the mass ratio of the brazing filler metal to the base metal as 40:60 are 436.57, 411.76, and 381.95 MPa, respectively, namely that the tensile strength of the joints decreases with increasing brazing pressure. Microhardness and EDS analysis of the joint fracture surface reveal that as the brazing pressure increases, the concentrations of melting point depressant elements and active elements at the fracture surface become higher, and the microhardness significantly increases. This indicates that higher brazing pressure leads to uneven microhardness distribution in the joint, inducing significant stress concentration and thereby reducing joint strength. XRD results confirm that the applied brazing pressure causes noticeable lattice distortion in the joint and base material. Higher brazing pressure results in greater lattice distortion, which blocks the diffusion channels of melting point depressant elements and active elements, hindering their diffusion. This leads to the accumulation of these elements in the joint and base material, thereby causing uneven microhardness distribution and a decline in joint strength. Post-welding heat treatment or increasing the brazing temperature can alleviate lattice distortion, enhance element diffusion, and improve the mechanical properties of the joint. [Conclusion] Applying a certain pressure during the preparation of wide-gap brazed joints helps suppress the formation of internal pores. However, the contradictory effects of brazing pressure and temperature on lattice distortion need to be carefully considered. Excessive brazing pressure can hinder element diffusion, while increasing the brazing temperature can enhance element diffusion, reduce the unevenness of microhardness distribution, and ultimately improve the mechanical properties of the joints.

[Objective] As a new kind of high-temperature materials, refractory high-entropy alloys have a wide application prospect because of their excellent high-temperature performance. However, their poor plasticity at room temperature has become the main factor limiting their development. Among many refractory high-entropy alloy components, TiZrTaNbMo has good biocompatibility and has attracted extensive research interest. Similarly, the alloy also has the disadvantage of poor plasticity at room temperature, which limits the development of the alloy. Ta element is the element with the highest melting point in the component. So far, the mechanisms underlying the influences of Ta element on the microstructure and mechanical properties of the alloy system have remained unclear. [Methods] The influences of the decrease in Ta content on the microstructure and properties of TiZrTaNbMo refractory high-entropy alloy were studied. In this study, the x value in TiZrTa_xNbMo which reflected Ta molar ratio was 0.8, 0.9, and 1.0, and the molar ratio of other elements remained unchanged. TiZrTa_xNbMo (x=0.8, 0.9, 1.0) series refractory high-entropy alloys were prepared by non-consumable high-vacuum arc furnace melting, and the alloy matrix was annealed at 1 000 ℃/6 h, which was followed by natural cooling with the furnace. The phase structures of the alloys were determined by an X-ray diffractometer (XRD). The microstructures and element distributions of the alloys were characterized by a scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The Vickers hardness of the alloys was measured by a microhardness tester. [Results] The TiZrTa_xNbMo refractory high-entropy alloys are composed of the primary BCC₁ phase and the secondary BCC₂ phase, showing a typical dendritic structure. With the increase in Ta content, the interdendritic region becomes smaller. Ta, Nb, and Mo elements are enriched in the branches, while Ti and Zr elements are enriched in the interdendritic region. The decrease in Ta content reduces the segregation of Nb and Mo elements in the branches. In terms of mechanical properties, increasing Ta content increases the hardness of the alloys from 433 HV to 501 HV. The experimental results indicate that the change in Ta content does not cause the change in the crystal structures of the alloys, and they still have a BCC biphase structure. The decrease in Ta content leads to the enlargement of interdendritic region of metal dendritic structure. Reducing Ta content is helpful to reduce the segregation of elements, especially for Ti and Zr elements with lower melting points. [Conclusion] In this study, the original design of refractory high-entropy alloys with an equal molar ratio is changed, and the composition is optimized. The microstructure and mechanical properties of the alloys are improved by the adjustment of element content. The research results will help to promote the further application of the TiZrTaNbMo refractory high-entropy alloy system.

[Objective] 304 stainless steel is a chromium-nickel stainless steel with austenite as the main crystal structure. It is widely used in the aerospace, marine, and chemical industries for its excellent heat and corrosion resistance. However, its hardness is low, and its cavitation erosion resistance is poor. When it is used as a material for turbine blades, exposure to complex environmental conditions leads to surface pitting and spalling, which severely shortens the service life of the blades. [Methods] To enhance the service life of 304 stainless steel, a novel iron-based alloy cladding layer was fabricated on its surface by using laser cladding. The obtained iron-based alloy cladding layer was subjected to phase analysis, microstructural observation, EBSD analysis, hardness testing, and cavitation erosion testing to analyze its phase composition, crystallographic characteristics, microhardness, and cavitation erosion resistance. [Results] The results show that the iron-based alloy cladding layer is mainly composed of α-Fe phase and Cr₂₃C₆ phase. The cladding layer has good forming quality without microcracks and with only a few pores. The microstructure of the cladding layer shows typical non-equilibrium solidification structure characteristics, which is composed of dendrites and interdendritic network structures, showing the morphologies of planar crystals, cellular crystals, columnar crystals, and equiaxed crystals from the bottom region to the top region. The EBSD results show that high-density grain boundaries were formed in the cladding layer and no obvious texture was formed. The cross-sectional microhardness of the cladding layer fluctuates between 640 HV_0.2 and 750 HV_0.2, which is considerably higher than the microhardness of the 304 substrate (187.6 HV_0.2). The higher microhardness of the cladding layer is attributed to solid solution strengthening, the second phase strengthening by Cr₂₃C₆ and Cr₇C₃ hard phases distributed among cellular dendrites, and grain boundary strengthening brought by high-density grain boundaries. The cumulative mass losses of the 304 substrate and the iron-based alloy cladding layer after cavitation erosion test for 300 min are 24.8 mg and 7.8 mg, respectively. The mass loss of the iron-based alloy cladding layer is about 31.5％ of that of the 304 substrate. During the whole cavitation erosion test, the cumulative mass loss of the iron-based alloy cladding layer is less than that of the 304 substrate. The surface analysis results after the cavitation erosion test show that the shear waves generated by the collapse of bubbles can cause stress accumulation on the surface of the material, thereby promoting the formation of slip bands. Cracks are prone to generation and expansion on the slip bands, eventually leading to material spalling and forming cavitation pits. Small grain sizes, a high grain boundary density, and high microhardness are the key reasons for the excellent cavitation erosion resistance of the cladding layer. [Conclusion] The higher microhardness of iron-based alloy cladding layer significantly improves the cavitation erosion resistance of the 304 stainless steel substrate. In this study, a high-microhardness iron-based alloy cladding layer for surface modification of 304 stainless steel was designed and prepared to promote the application of laser cladding technology in the reinforced coatings for turbine blade surfaces to a certain extent.

[Objective] With the increasing global attention to climate change and the implementation of the “dual carbon” goals, the resource utilization of CO₂ has become a pivotal research focus worldwide. However, the inherent chemical stability of CO₂ poses significant challenges for its chemical fixation and conversion under mild conditions, where catalyst design plays a decisive role. While the carboxylation of ethylene oxide (EO) with CO₂ to synthesize ethylene carbonate (EC) is recognized as an effective approach for energy conservation and low-carbon development, substituting EO with bio-based ethylene glycol (EG) offers a safer, eco-friendly, and renewable alternative. To address the thermodynamic limitations and low conversion rates in the direct synthesis of EC from EG and CO₂, this study aims to construct a synergistic catalytic system combining alkaline ionic liquids with Brønsted acids, thus developing a bifunctional catalyst for efficient CO₂ activation and EG conversion under mild conditions. [Methods] Three alkaline ionic liquid catalysts, including [DBUH]PHY, [TBDH]PHY, and [DBUH]TBD, were synthesized using 1, 8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1, 5, 7-triazabicyclo[4.4.0]dec-5-ene (TBD), and phenol as precursors. Their chemical structures and thermal stability were verified through Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). The synergistic catalytic performance was evaluated in a high-pressure autoclave using various Brønsted acids (H₂SO₄, H₃PO₄, CH₃COOH) under optimized conditions. [Results] When used individually, either the ionic liquids or Brønsted acids show low catalytic activity (less than 10.54％ yield). However, the combined [DBUH]PHY and H₂SO₄ system achieves a remarkable EC selectivity of 97.80％ and a yield of 20.89％, outperforming single-component systems. Density functional theory (DFT) calculations reveal that H₂SO₄ protonates EG to form carbocation intermediates, while the [DBUH]⁺ cation activates CO₂ via a strong binding energy (-61.94 kJ/mol), forming DBU-carboxylate (DBUH-CO₂). The PHY-anion facilitates dehydrogenation to generate oxyanions, synergistically driving EC formation and catalyst regeneration. Compared to conventional CeO₂-based catalysts (conversion rate is no more than 2％), this synergistic catalytic system demonstrates superior atomic efficiency under mild conditions (120 ℃, 3.0 MPa). [Conclusion] This study constructed a synergistic ionic liquid/Brønsted acid catalytic system, offering a novel strategy for the green conversion of CO₂ and diols. The developed bifunctional catalyst integrates CO₂ activation and EG protonation capabilities, with the proposed mechanism validated by experimental and computational insights. This sustainable synthesis route aligns with green chemistry principles, providing a viable pathway to mitigate greenhouse effects and enhance resource utilization. The findings hold significant implications for advancing the green transformation of the chemical industry, supporting carbon peak and neutrality goals, and fostering the development of circular economy.

[Objective] Ferroelectric films with lead zirconate titanate as a typical perovskite phase are widely used in ferroelectric memories, film capacitors, and microelectromechanical systems due to their excellent comprehensive electrical properties. The electrical performance of PZT ferroelectric films is a crucial factor in the design and manufacturing of devices, directly influencing their service life. Another issue that cannot be ignored is how to prepare high-performance PZT films efficiently. Therefore, in the pursuit of efficient preparation of PZT films, it is necessary to consider factors influencing their electrical performance for meeting the performance requirements of different devices. Microwave annealing can effectively reduce the heating temperature or heating time during the preparation process of ferroelectric films, which is commonly applied in efficiently preparing high-performance PZT ferroelectric films. During the microwave annealing process, the selection and characteristics of the substrate materials can significantly influence the performance of the films and therefore need to be studied in depth. [Methods] To effectively utilize microwave annealing to synthesize functional films, this study investigated the heating behavior of Nb-doped SrTiO₃ (Nb:SrTiO₃) single crystal substrates with different Nb doping amounts in microwave magnetic field and explored the interaction between microwave and materials. Afterward, amorphous Pb(Zr₄₀Ti₆₀)O₃(PZT) films were deposited on these Nb:SrTiO₃ substrates by a sol-gel method, which were then crystallized by microwave annealing. The study also investigated the effects of microwave annealing on the microstructure and electrical properties of PZT films. [Results] The results indicate that the heating behavior of the Nb:SrTiO₃ substrate depends on factors such as its conductivity, skin depth, and thickness. For the single crystal substrate with relatively high conductivity, its heating temperature can be ensured by regulating microwave output power. As the Nb doping amount in Nb:SrTiO₃ substrates increases, the heating temperature and heating rate of the substrates in the microwave magnetic field gradually decrease. Considering the effects of skin depth and thickness, the substrate with the Nb mass fraction of 0.05％ exhibits the best heating behavior in the microwave magnetic field. Microwaves directly interact with the charged defects within the material, reducing the internal defects of the PZT film and thereby achieving rapid crystallization of the PZT film. Meanwhile, the pinning effect of the film on the ferroelectric domains is weakened, which makes the PZT film show a saturated P-E hysteresis loop and thus further improves the polarization intensity of the PZT film. [Conclusion] Microwave annealing can crystallize ferroelectric films into a perovskite phase in a short time, realizing the rapid preparation of PZT films at high temperatures and improving the electrical properties of PZT films. Additionally, this effect is more obvious with the increase in microwave power.

[Objective] Martensitic stainless steel (0Cr13Ni5Mo) has good forging, casting, and corrosion resistance performance and is therefore widely used in hydropower, chemical industry, and high-pressure vessels. However, the special working environment can accelerate failure of the 0Cr13Ni5Mo material, especially for hydraulic flow passage components which are subjected to sand impact and corrosion due to the complex water body. Therefore, it is necessary to take certain protective measures to improve the surface properties of the 0Cr13Ni5Mo material and thereby delay its failure. [Methods] To enhance the service life of the flow passage components, iron-based alloy coatings with different Nb content (0％, 5％, 7％, and 9％) were prepared on the surface of the 0Cr13Ni5Mo substrate by laser cladding technology. X ray diffraction (XRD), scanning electron microscopy (SEM), a Vickers hardness tester, and an electrochemical workstation were used to investigate the effects of Nb addition on the microstructure, phase composition, microhardness, and electrochemical properties of the iron-based alloy coatings. [Results] The results show that the microstructure consists of grey matrix, massive and petal-like VC reinforced phases, and reticulated Cr carbides. With the increase in Nb content, the size of massive and granular Nb carbides in the matrix increases gradually, and the carbide morphology changes from massive and granular to petal-like and butterfly-like, and the reticulated Cr carbides decrease gradually. The phase composition analysis shows that the four coating samples prepared by laser cladding are composed of martensitic phase with BCC structure, austenitic phase with FCC structure, carbide reinforced phase VC, and Cr₂₃C₆ phase. With the increase in Nb content, the peaks of NbC phase appear in the XRD curves of S2, S3, and S4 samples, indicating that the carbide reinforced phase NbC is generated by the in-situ reaction of Nb during the laser cladding process, and the austenitic phase in the matrix increases gradually. The microhardness of all samples increases with the addition of Nb, with the S3 sample exhibiting the highest microhardness of 645 HV. In electrochemical tests, the self-corrosion potential of the samples gradually increases with the increase in Nb content, and the self-corrosion current gradually decreases. Samples S3 and S4 show typical anodic polarization characteristics, including the active dissolution zone, the passivation zone, and the over-passivation zone which is formed after the rupture of the passivation film. Sample S4 has a large amount of carbides, which causes micro-electro-coupling corrosion, leading to a decrease in corrosion resistance. Sample S3 has the best electrochemical performance with a self-corrosion potential of -179.3 mV, and the self-corrosion current density is only 10.3％ of that of sample S1 and reaches 9.258×10^-8 A/cm². Its improved corrosion resistance is due to the Cr reduction in the MC-type carbides, which results in the dissolution of more Cr into the matrix phase and thereby an increase in the Cr content in the matrix phase. [Conclusion] In this study, a Nb-containing iron-based alloy coating of 0Cr13Ni5Mo material for hydraulic flow passage components was designed and prepared to promote the development of laser cladding technology for surface-strengthened coatings of flow passage components to a certain extent.

[Objective]The use of carbon steel in high-temperature working conditions is strictly limited due to its poor oxidation resistance. Ni-Al intermetallic compounds have many practical industrial applications due to their high melting points and good high-temperature oxidation resistance. In this study, a Ni-Al reaction-modified coating was prepared on the surface of carbon steel to explore the further application of coatings containing Ni-Al intermetallic compounds with high-temperature oxidation resistance and improve the high-temperature service life of carbon steel. [Methods]A Ni-WC coating was prepared on the carbon steel substrate by high-velocity oxygen-fuel (HVOF) spraying, and then an Al coating was prepared on it by arc spraying. The Ni-Al within the coating reacted under diffusion treatment for different time at 800 ℃ to afford intermetallic compounds and thereby enhance high-temperature oxidation resistance. The high-temperature oxidation resistance of the coating was tested by recording their oxidation weight gain curves. [Results]The results show that the Al/Ni-WC composite coating generates Al-rich Ni-Al intermetallic compounds by in-situ reaction at the Al/Ni interface during high-temperature oxidation. The Al/Ni-WC coating forms Al-rich NiAl₃ during diffusion treatment at 800 ℃, and the Al atoms on the surface react with the atmospheric oxygen atoms to form Al₂O₃. With the extension of the reaction time, the NiAl₃ phase formed at the Al/Ni interface is transformed into the Ni₂Al₃ phase with better high-temperature oxidation resistance. The two Ni-Al intermetallic compounds have high melting points and high-temperature oxidation resistance, and Al₂O₃ formed on the surface of Al/Ni-WC composite coatings slows down the diffusion of O atoms. The thickness of the diffusion layer of the Al/Ni-WC composite coating increases almost linearly with the prolongation of the diffusion treatment time. The thickness of the NiAl₃ layer of the Al/Ni-WC coating after the diffusion treatment at 800 ℃ increases at a fast rate, and a thicker Ni₂Al₃ layer is generated by in-situ reaction after 10 h of heating. After 20 h of diffusion treatment at 800 ℃, a Ni₂Al₃ layer slightly thicker than the NiAl₃ layer is generated by in-situ reaction. Due to the higher melting point and stability of the Ni₂Al₃ layer, the Al/Ni-WC coating after diffusion treatment at 800 ℃ has better high-temperature oxidation resistance. After cyclic oxidation, there are ceramic phases Al₂O₃ and WC as well as NiAl phases in Al/Ni-WC coating subjected to 50 h of diffusion treatment at 900 ℃, which also show better high-temperature oxidation resistance under the combined effect of ceramic phases and NiAl phases. In this paper, the thickness of the diffusion layer of the Al/Ni-WC coating after diffusion treatment for different time was also measured, and the diffusion relationship between Ni and Al was obtained. The kinetic index of diffusion reaction is 0.790 45. The protective effect of the composite coatings on the carbon steel substrate is improved significantly. [Conclusion]The high-temperature oxidation resistance of the carbon steel substrate is significantly improved under the combined effect of the Ni-Al intermetallic compounds and Al₂O₃ film formed during the oxidation process as well as the original WC in the coating. As indicated by the oxidation weight gain experiment, after the introduction of ceramic phases in the Ni layer, the high-temperature oxidation resistance of the metal-ceramic composite coating is significantly better than that of the carbon steel substrate, namely that the carbon steel substrate can be better protected by the coating.

[Objective]In recent years, the development and progress of science and technology has brought many conveniences to people's production and lives, whereas potential hazards (such as vibration and noise) have also arisen. The generation of vibration aggravates the damage of parts, and the emergence of noise endangers people's health. To deal with these problems, damping alloys that can absorb vibration energy have gradually garnered people's attention. However, traditional damping alloys have a single damping mechanism and poor mechanical performance, failing to realize a variety of practical applications. Therefore, it is urgent to develop a new material that takes into account both. The emergence of multi-principal-element alloys makes the idea possible. The unique construction makes the alloys have good mechanical properties and damping properties. Therefore, it is of great significance to study the relationship between the microstructure and damping properties of multi-principal-element alloys. [Methods]To realize good damping properties and excellent mechanical properties of alloys, Fe₃CoNiCuCr_x (x=2.0, 2.5, 2.75, 3.0, 3.5) medium-entropy alloys were prepared by an arc melting furnace and a vacuum induction furnace. The phase structures of the alloys were studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The microstructure, phase distribution, and phase volume fraction of the alloys were characterized by a scanning electron microscope equipped with an electron backscatter diffraction (EBSD) probe. The tensile properties of the alloys were tested by a universal mechanical testing machine, and the damping properties of the alloys were tested by a dynamic mechanical analyzer. The effects of the variation of the Cr molar ratio on the phase composition and damping properties of the alloys were studied by increasing the molar ratio of the Cr element. [Results]The phase composition of the alloys changes from the face-centered cubic (FCC) phase to the FCC phase and the body-centered cubic (BCC) phase with the increase in the molar ratio of the Cr element. The formation of the two-phase structure makes the phases in the alloys grow competitively, thus reducing the average grain size of the alloys. The tensile strengths of the alloys increase from 329 MPa to 779 MPa. However, the plasticity of the alloys deteriorates, and the plastic strain is reduced from 35.45％ to 1.72％. When the Cr molar ratio reaches 3.0, the damping capacity index of the alloy reaches the highest value of 0.052. With an increase in the molar ratio of the Cr element, the volume fractions of the BCC phase in the alloys gradually increase, which improves not only the tensile strengths of the alloys but also their ferromagnetic damping properties. The match of the volume fractions and morphologies of the FCC and BCC phases improves the interface damping properties of the alloys, and the unique mesh structure formed by embedding the soft FCC into the hard BCC matrix improves the damping properties of the alloys to a certain extent. [Conclusion]Under the joint influence of ferromagnetic damping, interface damping, and morphologies of the alloy, the Fe₃CoNiCuCr_3.0 alloy has not only excellent tensile properties but also high damping properties.

[Objective] Magnesium alloy is widely used due to its advantages of light weight, high specific strength, high specific stiffness, and easy recovery. The parts of magnesium alloy in the front of automobiles and aircraft as well as the side and tail of automobiles are exposed to impact loads at a high strain rate. This causes structural parts to fail in a very short of time, posing a risk to safety performance of automobiles and aircrafts and resulting in unpredictable situation. Therefore, studying the quasi-in-situ deformation processes and mechanisms of magnesium alloys under dynamic compression at a high strain rate is of important significance. [Methods] To study the dynamic mechanical performance of AZ31 magnesium alloy under dynamic impact loads, this study systematically investigated an extruded-sheared AZ31 magnesium alloy under biaxial dynamic compression. Based on the quasi-in-situ method, dynamic compression experiments were conducted on AZ31 magnesium alloy with the split Hopkinson pressure bar (SHPB). The microstructure evolution of the specimens was characterized by electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). [Results] The results of biaxial dynamic compression experiments show that the AZ31 magnesium alloy exhibits plastic deformation. A large number of extension twins were activated under radial compression in the extrusion direction. Detwinning accompanied with activation of a small number of extension twins was observed during the reverse loading. The in-depth analysis of the detwinning behavior indicates that the higher Schmid factor (SF) is mainly accounted for detwinning. The slip trace method was used to determine the slip system activated and combined with the detwinning behavior for investigating the contribution of slip to detwinning. When compression was perpendicular to the crystal c-axis, extension twins were easily activated during this process, and the twin had an angle of 86.3° relative to the parent grain. The c-axis of the twin was nearly parallel to the direction of compression. When the compression direction was changed to perpendicular to the c-axis of the twin, detwinning occurred. With the accumulation of cumulative strain, the peak value of low-angle grain boundaries (LAGBs) continued to increase. The whole deformation process was accompanied by slip. These results indicate that the generation of LAGBs is caused by slip, and slip plays a crucial role in plastic deformation. During the plastic deformation of the AZ31 magnesium alloy, the twins activated first exhibit detwinning with the change of compression direction. Slips are activated throughout the dynamic compression process, despite the fact that the direction of dynamic compression is adjustable. Both twinning and detwinning processes are accompanied by slip. The synergy between slip and twinning is primarily responsible for the dynamic compression deformation of AZ31 magnesium alloy in various directions. [Conclusion] In this paper, the microstructure deformation behavior of AZ31 magnesium alloy was studied to provide a theoretical basis for its wide application.

[Objective] Cemented carbides are a class of alloy prepared by high-temperature sintering in which micron-scale refractory metal compound (WC, TaC, TiC, and NbC) powder is taken as the hard phase and the transition metal (Co, Fe, and Ni) powder as the sintering bonding phase. They are widely used in tool materials and other industrial fields, known as “industrial teeth”, due to their high hardness, high strength, wear resistance, corrosion resistance, and good high temperature performance. With the development of China′s strategic emerging industries, aerospace, marine engineering, CNC machine tools, rail transit, nuclear engineering, new energy, advanced medical equipment, environmentally-friendly and energy-saving equipment, and other high-end manufacturing industries have an increasing demand for high-performance and high-stability tool materials. Tool performance can be further enhanced by the use of coating and other surface treatment methods to coat the solid lubricant on the tool surface, or the addition of the solid lubricant as an additive to the tool material matrix, which leverages the advantage of high temperature stability of solid lubricants to form a continuous solid lubrication layer on the service tool surface. [Methods] In this study, spherical composite powder was prepared by ball milling using WC-Co cemented carbide powder (particle size 15-45 μm) as wear-resistant component and graphite powder (particle size 80-200 μm) as the solid lubricant. The composite powder was deposited to be graphite/WC-Co coating by plasma spraying process. A high current pulsed electron beam (energy density 27 keV, pulse interval 15 s) was used for irradiation treatment, with number of irradiation times set as 1, 10, 20, and 30. The microstructure and mechanical properties after treatment were observed. [Results] After treatment with the high current pulsed electron beam, the surface of the remelted coating is compact and flat, with a modified layer thickness reaching 294 μm, the highest surface hardness can reach 800 HV, an average friction coefficient as low as 0.10. The microstructure analysis shows that nano-sized WC phase, Co₃W₉C₄ phase, and diamond-like structure are formed on the surface of the coating after high current pulsed electron beam irradiation, which greatly improves the microhardness of the coating surface. The bulk graphite on the surface of the coating is dissolved by the electron beam and then re-precipitates into elliptic graphite. At the same time, the graphite is separated into graphene sheets under the action of the electron beam, which are uniformly covered on the surface of the coating and effectively reduce the friction coefficient of the coating surface. Part of the graphite is transformed into a diamond structure, which effectively improves the surface hardness of the coating. [Conclusion] In this study, a two-step technology of thermal spraying deposition and high current pulsed electron beam modification was used to prepare a uniform, compact, and fine WC-Co alloy, which induced the composite carbon structure of spherical graphite, graphene, and diamond, effectively improving the hardness of the coating and reducing the friction coefficient of the surface. The prepared nano-composite self-lubricating coating provides a new material for the high-end equipment manufacturing tool industry.

In order to reduce the sintering temperature of MgTiO₃-(Ca_0.8Sr_0.2)TiO₃(MT-CST) microwave dielectric ceramics and improve their microwave dielectric properties, the A-site Zn²⁺ doping was performed on MT-CST ceramics by chemical precipitation method, the effects of Zn²⁺ doping on the microstructure, sintering temperature and microwave dielectric properties of MT-CST ceramics were studied. The results show that the substitution of Mg²⁺ by Zn²⁺ can increase the density of ceramics, reduce the dielectric loss and improve quality factor value. The sintering temperature of MT-CST ceramics can be successfully reduced to 1 125 ℃. The as-prepared ceramics have excellent microwave dielectric properties, with dielectric constant of 21.6, quality factor of 50 800 GHz and temperature coefficient of resonance frequency of 0.24×10^-6/℃, respectively.

In order to reveal the influence of base oil viscosity on the rheological properties of complex titanium grease, four greases were prepared by using four base oils with varying viscosities, then the yield limit, thixotropy and shear-time-dependence of each grease were investigated. The morphologies of soap fibers of each grease were characterized by scanning electron microscope (SEM). Under steady shear flow conditions, the rheological parameters of each grease were tested using an R/S+ rotating rheometer. Test results indicate that the soap fibers from each grease are found to form agglomerate and interconnective network morphologies, the viscosity of base oil regularly affects the rheological properties of lubricating grease, and the increasing viscosity of base oils leads to the width increase of soap fibers and the cavity enlargement among them, which in turn enhances the yield limit, thixotropic energy, viscosity and shear resistance of the greases.

Atomic manufacturing refers to the technology that directly applies energy on atoms to precisely and controllably remove or add atoms, thereby manipulating the structures and properties of materials. To achieve the precision and controllability of atomic manufacturing, multi-scale real-time observation and detection are imperative. In-situ transmission electron microscopy technique not only allows real-time study of the relationship between the structures and properties of nanomaterials at the atomic scale, but also enables the construction of atomic-level devices and in-situ detection of their performances. This article focuses on the significant progress made by in-situ transmission electron microscopy technique in the processing, device construction, and in-situ detection at the nanometer/atomic precision level. The article outlines the challenges and future development directions for the visualization and in-situ detection of atomic manufacturing processes using current in-situ transmission electron microscopy technique.

Barium titanate (BaTiO₃) based positive temperature coefficient resistance (PTCR) ceramics are widely employed in the production of various thermistor devices due to their unique resistance-temperature characteristics. With the increasingly urgent demand for lead-free electronic materials and components, the lead-free development of high-Curie-temperature BaTiO₃-based PTCR ceramics is an inevitable trend. This article first introduced the physical mechanism of PTCR effect, the performance indicators and influencing factors of BaTiO₃-based PTCR ceramic materials, and then reviewed the research progress of high-Curie-temperature lead-free BaTiO₃-based PTCR ceramic materials. Finally, strategies and approaches to improve the performance of lead-free BaTiO₃-based PTCR ceramic materials were discussed, and future prospects were proposed from manufacturing, performance and device aspects for the promotion of further development in this field.

In order to analyze the catalytic performances of heteropolyacid ionic liquid catalyst, a functionalized heteropolyacid ionic liquid catalyst ([HO-(CH₂)₂-mim]₅[Ti(H₂O)FeMo₁₁O₃₉]) was prepared by ion exchange between the heteropolyacid anion prepared with Fe as the central heteroatom and Mo as the coordination atom and 1-hydroxypropyl-3-methylimidazole salt cation. The FT-IR, UV, XRD and TGA were used to characterize the structure of the catalyst, the process parameters were optimized by orthogonal tests, and the effects of feed ratio, catalyst dosage, temperature and time of transesterification reaction on the catalytic performances of heteropolyacid ionic liquid catalyst were discussed. The experimental results show that the as-proposed catalyst has correct structure, well thermal performance and good catalytic effect. In the optimum process conditions, feed ratio is 2, mass fraction of catalyst is 1.0％, reaction temperature is 220 ℃ and reaction time is 5 h. The PES yield prepared under the optimum condition is 75.32％.

In order to solve such problems as gravity stratification in the conventional preparation process of Cu-Fe alloys, the strip cast-rolling process featuring the sub-rapid solidification characteristics was employed in this study to suppress the liquid phase separation. Through the coupling of Marangoni effect and thermophoretic force, the experimental parameters were adjusted in strip cast-rolling accordingly to obtain the 2.2~2.4 mm thin strips containing Cu-20%Fe and Cu-30%Fe with controllable ferromagnetic phase size and distribution. Metallographic and EBSD analysis confirms that the cast strip forms a “sandwich” layered composite structure composed of Cu phase-Fe-rich phase-Cu phase, and Fe phase was distributed in the Cu-20%Fe cast strip more uniformly. The EBSD analysis further shows that many low-energy grain boundaries, such as Σ1 and Σ3, etc., are formed in the solidified layer. The Cu-20%Fe alloy was rolled from 2.4 mm to 0.4 mm, and consecutively rolled to 0.12 mm after heat treatment at different temperatures. Results show that the performance of the rolled plate subjected to the heat treatment at 450 ℃ is better, with its IACS reaching 50% at least, tensile strength higher than 600 MPa, uniform elongation reaching 7.5%, and the saturated magnetization above 4.24×10⁵ A/m.

In order to study the effect of different twin volume fractions on the adiabatic shear sensitivity of materials, AZ31 magnesium alloys with different twin volume fractions were obtained by pre-compression. The hat-shaped samples were subjected to high speed impact at the temperature of 200 ℃ and the strain rate of 944 s^-1 by using split Hopkinson pressure bar (SHPB). The microstructure evolution before and after high strain rate deformation was characterized by electron backscatter diffractometer (EBSD) and optical microscope (OM). The absorbed energy of samples during adiabatic shear process was calculated, and the micro-hardness within and without the adiabatic shear band(ASB)was tested. The results show that the adiabatic shear band can be found in samples with different twin volume fractions. With the increase of twin volume fraction, the width and absorb energy of the adiabatic shear band decrease, while the adiabatic shear sensitivity increases.

In order to improve the magnetic properties and corrosion resistance of sintered NdFeB, grain boundary doped Al₆₅Cu₂₀Fe₁₅ nanoparticles were used to prepare sintered NdFeB magnets with high performances, and an electrochemical workstation was used to investigate the corrosion behaviour of doped magnets in 3.5％NaCl solution. The results show that the doping of Al₆₅Cu₂₀Fe₁₅ nanoparticles can form a low melting point phase in the magnet, improve the wettability between the grain boundary and the main phase, inhibit the magnetic coupling among the hard magnetic phase, and enhance the magnetic properties of the magnets. When the mass fraction of Al₆₅Cu₂₀Fe₁₅ nanoparticles is 0.4％, the magnet has the highest magnetic force with the coercivity of 978.1 kA/m, the maximum magnetic energy product of 270.3 kJ/m³ and the remanence of 1.208 T. Compared with the undoped magnet, the corrosion potential of magnet doped with 0.4％ Al₆₅Cu₂₀Fe₁₅ nanoparticles increases from -0.881 6 V to -0.704 0 V, while the corrosion current density decreases from 78.292 9 μA/cm² to 33.222 9 μA/cm², and the arc radius of high frequency capacitive reactance is much larger than that of the undoped magnet. Therefore, the corrosion resistance of the magnet can be effectively improved.

In order to study the thermal deformation behavior of low-cost titanium alloy, a Ti-5Al-1.5Mo-1.8Fe alloy was compressed for hot compression experiment by using Instron 5869 thermal compressor. Six machine learning models taking deformation temperature, strain rate and the degree of strain as input variables and adopting flow stresses as output variables were established. The flow stress values of alloy under different conditions were predicted and the prediction performance of these models were evaluated. The predicted processing map was drawn according to the prediction data of LSTM neural network model with the best prediction performance, and the predictive ability of the model was evaluated and verified by its comparison with experimental processing map. The results show that the processable regions of Ti-5Al-1.5Mo-1.8Fe alloy with the strain of 0.499 can be accurately reflected by the predicted processing map, in good accordance with the experimental map. The as-proposed method has better prediction for the thermal deformation behavior of Ti-5Al-1.5Mo-1.8Fe alloy.

To study the formation sequence and mechanism of intermetallic compounds in Al/Cu coatings, Al/Cu coating was prepared on 304 stainless steel substrate. Subsequently, the samples were heat treated to obtain intermetallic compounds by in-situ reaction within Al/Cu coating. In addition, the oxidation resistance of the coating at high temperatures was tested. First principles were used to calculate the enthalpy, entropy, Gibbs free energy and heat capacity of Al-Cu intermetallic compounds. Through the combination of thermodynamics with diffusion dynamics, an effective free energy of formation model was proposed to predict the formation sequence of compounds at the Al/Cu interface. The results show that the Al₂Cu phase is formed first within the Al/Cu coating, the AlCu phase appears at the Al/Cu interface, and the Cu-rich Al₄Cu₉ phase appears as the heating time increases to 20 h. The formation sequence of Al-Cu intermetallic compounds is Al₂Cu→AlCu→Al₄Cu₉, which is obtained by first principle calculation and is consistent with the experimental results. The oxidation experimental results show that the coating has excellent oxidation resistance at high temperatures.

In order to further improve the strength of high entropy alloy (HEA) with FCC structure, a Ni₃₈Co₂₅Cr₁₅Fe₁₀Al₁₀Ti₁Nb₁ HEA was prepared by vacuum arc melting method. The results show that the solidified structure of HEA is composed of single-phase FCC, and the typical dendrite with composition segregation can be observed within the as-cast strip. Besides, the HEA shows high recrystallization resistance, and the recrystallization fraction is only about 45.1％ at the annealing temperature of 1 000 ℃. In contrast, a completely recrystallized structure can be achieved when the annealing temperature increases to 1 050 ℃. Homogenous microstructure with refined grain size is obtained with the fully recrystallized HEA, and the corresponding average grain size is about 4.25 μm. Excellent tensile properties can be obtained with the annealed Ni₃₈Co₂₅Cr₁₅Fe₁₀Al₁₀Ti₁Nb₁ HEA. When annealing at 1 000 ℃, the ultimate tensile strength is about 1 640 MPa with an elongation of about 20％. For the HEA annealed at 1 050 ℃, the ultimate tensile strength and the elongation are about 1 580 MPa and 28％, respectively.

In order to study the influence of hole location and size on fatigue crack propagation path, ABAQUS finite element simulation software was used to establish the simulation model of crack propagation for modified CT samples. By using the extended finite element method (XFEM), the influence of the angle and distance between the circular hole and the crack tip as well as the radius of circular hole on the crack propagation path of Q235 steel under low cycle fatigue was studied. By introducing the crack deflection coefficient, the influence of different parameters on the deflection degree of crack propagation path was described quantitatively. The results show that the crack deflection coefficient reaches the maximum value when the angle between the crack tip and the circular hole is 45°. The crack deflection coefficient increases with the increase of hole radius, while decreases with the increase of the distance between circular hole and crack tip.

In order to improve the energy storage density of Pt/PbZrO₃/Pt dielectric capacitors, PbZrO₃/Al₂O₃ heterostructure thin films were prepared on the Pt/Ti/SiO₂/Si substrate, where the Al₂O₃ layers with a thickness from 0 nm to 10 nm were deposited by thermal evaporation and natural oxidation methods. PbZrO₃ films were prepared by a chemical solution deposition method, and the effect of Al₂O₃ layer thickness on the energy storage performances of PbZrO₃/Al₂O₃ (PZO/AO) heterostructure thin films was studied. The results show that the electrical breakdown strength of PZO/AO gradually increases with the AO layer thickness, and the characteristics of polarization versus electric field (P-E) hysteresis loop changes from antiferroelectric form to ferroelectric form. The maximum energy storage density of 21.2 J/cm³ can be achieved when the thickness of AO layer is 5 nm.

In order to reveal the low-cycle fatigue deformation and fracture behavior of hot-extruded Al-5Cu-0.8Mg-0.15Zr-0.2Sc-0.5Ag alloy subjected to T6 treatment, the low-cycle fatigue tests were performed at both room temperature and 200 ℃ with this alloy at T6 state. The experimental results show that the relationship between plastic strain amplitude and load reversal cycle follows the Coffin-Manson formula at both room temperature and 200 ℃, while the relationship between elastic strain amplitude and load reversal cycle follows the Basquin formula. During the low-cycle fatigue deformation at both room temperature and 200 ℃ of the alloy, the deformation mechanism is mainly the planar slip at lower total strain amplitudes, while is mainly the wavy slip at higher total strain amplitudes. At both room temperature and 200 ℃, the low-cycle fatigue cracks initiate at the free surface of fatigue specimens and propagate in a transgranular mode.

In order to address the issue of lower electrode material activity and slower mass transfer rate of electrochemical oxidation water treatment technology, an electrochemical oxidation reactor under Flow-through mode was constructed by using a Ti₄O₇ foam electrode as anode with higher activity. The reactor was used to remove the typical fluoroquinolone antibiotic, namely ofloxacin (OFL). The influences of flow mode, membrane flux, current density and initial pH value on the degradation effect of OFL were investigated, and the degradation mechanism was explored. The results show that the removal rate of OFL reaches the maximum value of 97.66% after 120 minutes of reaction, when the membrane flux is 3.17 mL/(cm²·min), the current density is 7.5 mA/cm² under the Flow-through mode and the initial pH value is 3. The residual antibacterial activity of OFL vanishes after treatment, and the main active substances involved in the reaction are ·OH and SO^-₄·.

Aiming at the welding problem of CLF-1 steel for nuclear fusion, the vacuum laser welding (VLW) technology was used. The welding characteristics, microstructure and mechanical properties of VLW welds were studied. The results show that the metal vapour plume (MVP) gets well inhibited and the oxidation degree in weld metal (WM) decreases, with the reduce of vacuum degree. Compared with atmospheric laser welding (ALW), the heat input reduces by 20% approximately, the grain size of VLW weld decreases dramatically, whereas the sizes of M₂₃C₆ (elliptic carbides rich in Cr, Fe, W and C) and MX (high-density spheroidal carbides rich in Ta or V) reduce to some degrees, resulting in favourable dispersion strengthening effect. There is no residual ferrite (δ-Fe) in the weld microstructure. The impact toughness of VLW weld after high temperature tempering (PWHT) is 280 J, which is 43 J higher than that of base metal and 2.4 times as that of ALW weld. The fractograph of impact sample is ductile fracture.