Vacuum最新文献

Flexible electronics are expected to play a vital role in wearable systems and multifunctional smart electronic devices owing to their capacity to conform to various shapes. The amorphous AlInN film was synthesized on a Polyethylene terephthalate (PET) substrate via radio-frequency (RF) magnetron sputtering to fabricate a flexible AlInN ultraviolet (UV) photodetector. The device demonstrates a sensitivity of 1708, a detectivity (D*) of 3.11 × 10⁷ Jones and satisfactory photoresponse under 365 nm UV excitation. In particular, we carried out the flexibility experiments for device and analysis its photoresponse characteristics. After more than 100 times bending at about 90° angle, the photocurrent of the device remains at 97 % of its original value. These findings demonstrate the potential of AlInN films in the UV flexible photodetection and display an effective fabrication strategy for UV flexible photodetectors.

The motion stability of the vacuum arc between TMF contacts significantly affects the breaking capacity of vacuum switches. The vacuum arc movement can be effectively controlled by slots on the TMF contacts to provide the necessary driving force. However, the necessary cross-slot movement of the arc affects its stability. In this paper, a novel straight-slot transverse magnetic field (SSTMF) contact structure with additional auxiliary slots on the back is proposed to improve current distribution and avoid stagnation at the contact center. The simulation analysis was conducted on the force acting on the arc at different positions and the magnetic field distribution between the contacts. Additionally, the arcing experiments were performed in a demountable vacuum chamber for both novel and traditional SSTMF contacts. The SEM analyses were carried out for the contacts after the experiments. Combined with simulation and comparative experimental results, it is verified that the auxiliary slots can improve the control and driving effect on the arc. This can provide ideas and references for future contact design and improve the breaking performance of vacuum circuit breakers.

Loading active metals in forms of single atoms or nanocluster is considered as an effective approach for designing catalysts with high atomic utilization efficiency. However, synthesis single atoms or clusters precisely in large quantities is a challenge. In this work, the isolated diatomic sites (Ni, Co) decorated single crystal Pt cluster were synthesized as efficient catalyst for hydrogen evolution. Adjacent Ni and Co atoms optimize the electronic structure of Pt single crystal, effectively lowering the water dissociation barrier and ensuring optimal binding strength of intermediates throughout the reaction process. As results, the mass activity of 2.087 A mg⁻¹ was achieved under 200 mA cm⁻², approximately 3 times than that of Pt/C. Theoretical calculations reveal that diatomic Ni, Co decorated Pt cluster reduces the energy barrier for breaking the OH-H bond, as well as facilitating the preferential adsorption and dissociation of H*. This work provides an opportunity for regulation electronic structure of catalytic via decoration single crystal cluster with diatomic sites and provides guidance for designing high efficiency electrocatalysts for promising applications.

To clarified the influence of the scattering mechanism on thermoelectric properties α-Ag₂S, the relationship between the scattering lifetime and transport properties of the inorganic flexible material α-Ag₂S are investigated for the first time using first-principles calculation, Boltzmann transport theory, and the momentum relaxation time approximation (MRTA). Calculations reveal that the static dielectric constant, high frequency dielectric constant, and elastic constant are anisotropic. The acoustic deformation potential scattering (ADP), the ionized impurity scattering (IMP), the piezoelectric scattering (PIE), and the polar optical phonon scattering (POP) of α-Ag₂S are first calculated, and the IMP and POP are found to be the major contributions for scattering mechanism. Furthermore, it is also found that the transverse wave of α-Ag₂S effects on electrons along the XZ shear strain direction are non-negligible. These insights provide a new direction for the regulation of thermoelectric properties in α-Ag₂S by offering a deeper understanding of the scattering mechanisms.

AlCoCrFeNi high-entropy alloys (HEAs) has higher strength and wear resistance but poorer corrosion resistance. In the present investigation, the AlCoCrFeNi HEAs containing titanium(Ti) were fabricated via laser cladding to enhance the corrosion resistance properties of the coating and the influence of the Ti content on the microstructure of the coatings was investigated. The results show that the microstructure of the coating changed from a single BCC phase to a BCC + B2 phase with the addition of Ti. The Laves phases appeared within the coating when the Ti content was beyond 0.5 mol ratio. As an excellent corrosion-resistant element, Ti promoted the formation of a passive film and enhanced the corrosion resistance of the HEAs coating. The corrosion resistance of the coating first increased and then decreased with the addition of Ti, and the AlCoCrFeNiTi_0.5 coating exhibited optimal corrosion resistance.

The interface microstructure between the surface (TiNb)C-reinforced layer and TiNb substrate was fabricated through an in situ diffusion reaction in a vacuum environment. Microstructure, element composition, and phase distribution were investigated to elucidate the reaction process and formation mechanism of the transition phase at the interface. Indentation and fracture analysis were performed to assess the interface properties. The results indicated that there is a clearly banded microstructure existed between the surface-reinforced layer and TiNb substrate and that the phase in the transition region had an orthorhombic structure. The analyses revealed that the transition region formed at the front of the reaction interface, in which the main phase was (TiNb)₂C. The structure of (TiNb)₂C could be approximated as that of α-Nb₂C, and (TiNb)₂C reacted to form (TiNb)C with the further diffusion of C. Indentation analysis indicate that the apparent fracture toughness of the interface at different loads was 2.57–3.44 MPa m^1/2, higher than that of the surface-reinforced layer. The bending experiment further proved that the microstructure in the transition region was brittle but showed good resistance to interface crack propagation.

This study investigates the effects of various lubrication techniques on the surface integrity and fatigue life of FeCoCrNiAl0.6 high-entropy alloy during machining. By combining cutting experiments, fatigue tensile tests, and Abaqus/Fe-safe simulations, the research offers a comparative analysis of surface morphology, roughness, and fatigue life across different lubrication scenarios.The findings show a marked improvement in surface quality as cutting speed increases under all lubrication conditions. However, increased cutting depth generally leads to a decline in surface flatness. Specifically, surface roughness decreases with higher cutting speeds. For example, at 1200 m/min in dry cutting, the surface roughness is around 0.77 μm, which drops to 0.40 μm at 3000 m/min, representing a 48 % reduction. Under cryogenic minimum quantity lubrication (CMQL) at 1200 m/min, the roughness is 0.49 μm, decreasing to 0.25 μm at higher speeds, reflecting a 48.9 % reduction.However, increased cutting depth significantly deteriorates surface quality, with a notable rise in surface roughness values. Among the tested lubrication techniques, surface quality ranks as follows: CMQL > MQL > Dry.Regarding fatigue life, higher cutting speeds substantially enhance tensile cycle counts under all lubrication conditions. Specimens under CMQL achieved 2,000,042 cycles, compared to 1,238,520 cycles with minimum quantity lubrication (MQL) and 702,245 cycles in dry cutting—equating to 61.9 % and 35.1 % of the tensile cycle count for CMQL, respectively.Fatigue life decreases with greater cutting depth. For example, compared to a 0.2 mm cutting depth, tensile fatigue cycles decrease by 87.9 % for CMQL, 86 % for MQL, and 91.8 % for dry cutting at a depth of 0.5 mm.

MXene can generate high-temperature pulses (HTP) by the physical/chemical coupling effect under laser irradiance and is a good initiator for laser ignition. The main obstacle in the application on laser ignition of MXene based materials is the incomplete oxidation and reduced energy output resulting from the inert TiO₂ passivation layer. In this study, we proposed an efficient approach to significantly enhance the thermal oxidation and energy release under laser irradiance by decorating hydrophobic 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFTE). The CFx produced by the decomposition of PFTE under laser irradiance can react with Ti atoms on the surface of MXene to prevent the formation of the oxide layer. This process releases a large amount of heat and completely oxidizes MXene. As expected, some rutile nano-crystals are distributed on the surface of fully oxidized MXene and the energy output of MXene/PFTE composite is 6.1–8.3 kJ/g which is much higher than pristine MXene. The mechanism of the thermal oxidation process is proposed to explain the enhanced energy output of the MXene/PFTE by thermal analysis and time-resolved emission spectrum (TR OES). Furthermore, the MXene/PFTE membrane significantly enhanced the laser ignitibility of 2,4,6,8,10,12-(hexanitrohexaaza)cyclododecane (CL-20) reducing the laser intensity and shortens the ignition time.

Transition metal nanoparticles can act as seeds for the nucleation and growth of carbon nanotubes (CNTs). Adding molybdenum (Mo) to an iron (Fe) catalyst offers synergistic and beneficial features that enhance the yield of these nanostructures and influence their morphological and structural aspects. This study explored the development of Fe-Mo catalyst surfaces for CNT synthesis using a novel plasma-assisted surface alloying process. AISI 1005 low-carbon steel specimens were surface-alloyed with Mo by employing a DC argon-hydrogen mixed glow discharge at three different temperatures (800 °C, 1150 °C, and 1200 °C with an additional diffusion step). Subsequently, the Fe-Mo surfaces were used for CNT synthesis at 700 °C under a plasma-carburizing atmosphere (20 % CH₄ + 80 % H₂). The morphological, chemical, and structural aspects were assessed using material characterization techniques. The results indicate that Mo-enrichment temperatures and the resulting Mo content on Fe-Mo surfaces directly influence catalytic CNT growth and nanostructure morphology. Mo-rich intermetallic phases up to 71 wt% Mo hinders the CNT nucleation, while Mo in solid solution (0.7 wt% Mo) enhances CNT yield and improves their structural aspects. This study proves the feasibility of plasma surface alloying to produce Fe-Mo catalytic surfaces by controlling the processing parameters.

During the fixed abrasive polishing of silicon carbide, multiple abrasive particles on the polishing pad mechanically remove material from the workpiece surface. This study employs molecular dynamics simulations to examine the impact of grinding depth and abrasive particle spacing on surface morphology, subsurface damage, structural phase transformation, temperature, and mechanical properties of SiC. The results show that increasing grinding depth shifts the atomic removal mechanism from adhesion and plowing to cutting, while varying particle spacing affects removal efficiency. Subsurface damage, influenced by grinding depth and abrasive size, leads to crack formation due to temperature and stress. Radial distribution functions were used to identify changes in the diamond structure of SiC. Additionally, temperature and force are critical factors, increased grinding depth raises the temperature, and the grinding force of leading particles exceeds that of trailing ones, with larger particle radii causing higher normal forces. These findings offer theoretical guidance for improving the machining quality and performance of SiC workpieces in multi-abrasive particle grinding.