Epoxy resin patching is an engineering remedy for surface interfacial defects of Al2O3 ceramic high voltage (HV) bushings. However, heterogeneous interfaces between alumina and epoxy may introduce hidden service risks. In this work, Multiphysics simulation, material level characterization and nondestructive testing exploration were jointly performed to investigate the degradation behaviors and detectability of epoxy filled interfacial defects. Simulation results reveal that defects located on the outer main tube wall induce severe local stress concentration and electric field distortion; defect depth and exposed area dominate stress amplification, while thermal field perturbation remains limited. Experimental tests demonstrate that epoxy filling partially restores flexural strength of defective alumina, yet both flexural strength and dielectric breakdown strength are still significantly degraded compared with monolithic ceramic substrates. Even small patched defects raise dielectric loss evidently. Spectral characterization identifies distinguishable optical fingerprints for Al 2 O 3 ceramic and epoxy resin, whereas multispectral imaging cannot achieve direct defect visualization. Benefiting from large thermal conductivity mismatch, active infrared thermal imaging successfully identifies the position and approximate dimension of epoxy filled interfacial defects. This work provides Multiphysics understanding and feasible testing references for the safety evaluation of epoxy repaired alumina ceramic HV-bushings.
Fiber infrared evanescent wave-temperature dual sensor can detect both organic molecules and temperature, demonstrating potential applications in healthcare, petrochemical industries and advanced energy storage systems. However, current fiber sensors are strictly limited to either infrared evanescent wave or temperature sensing, primarily due to the absence of suitable fiber sensing media. Here, a high-performance infrared evanescent wave-temperature dual sensor based on single Ge[Formula: see text]Se3Te[Formula: see text] chalcogenide glass fiber is developed. The obtained fiber exhibits a high Seebeck coefficient of 1410[Formula: see text] [Formula: see text]V/K, a precise temperature resolution of 0.03[Formula: see text]K, a fast response time of 6[Formula: see text]s and superior infrared evanescent wave sensing performance. Furthermore, the fibers can be integrated into a textile to detect temperature distribution and simultaneously detect organic substances such as ethanol and urea. These findings highlight that the fiber with superior infrared evanescent wave-temperature sensing performance may find potential applications in multifunctional sensing.
Mid-infrared (MIR) lasers operating in the 2–6[Formula: see text][Formula: see text]m region are important for spectroscopy, sensing, communications, medicine, lidar, and electro-optical applications. Chalcogenide glasses and glass–ceramics are attractive MIR gain-media candidates because of their broad infrared transparency and low-phonon-energy hosts. This review focuses on recent progress in chalcogenide glasses and glass–ceramics toward practical MIR laser operation. Rare-earth-doped glasses and fibers are discussed from early MIR emission studies to recent Tb[Formula: see text]-, Ce[Formula: see text]-, and Pr[Formula: see text]-based laser demonstrations, with particular attention to low-loss fibers. For rare-earth-doped glass–ceramics, dopant partitioning among nanocrystals and glass–crystal interfaces is examined as a key factor governing spectroscopic performance. Transition-metal-doped systems, including Cr[Formula: see text]-, Co[Formula: see text]-, Fe[Formula: see text]-, and Ni[Formula: see text]-activated materials, are reviewed with emphasis on crystal-field engineering and crystallization-induced optical loss. Bulk, fiber, waveguide, and microcavity platforms are further compared in terms of gain–loss balance and their suitability for practical MIR laser operation.
The current generation process by an array of Nitrogen-Doped Carbon Nanotubes (N-CNTs) during and after vibration was investigated. It was established that the N-CNT array not only converts external mechanical energy into electrical energy due to the piezoelectric effect but also accumulates charge due to deformation and the formation of a potential barrier at the interface between bamboo-like bridges and the nanotube sidewall. The duration of the post-vibration current varied with the structural characteristics of the N-CNT arrays and the preceding vibration exposure and ranged from several minutes to approximately 5 days. The obtained results demonstrate the possibility of using the N-CNT array simultaneously as an active piezoelectric layer of a nanogenerator and as an efficient charge storage element to provide continuous power supply for electronic devices by converting ambient mechanical energy.
