Key Takeaways & Executive Findings
- •• Hierarchical polyimide nonwoven fabric with ultralow-reflectivity EMI shielding and high-temperature resistant infrared stealth is fabricated via alkali treatment, in-situ growth of magnetic particles, and self-activated electroless Ag plating. • Impedance matching structure assembled from Fe3O4/Ag-loaded PI (PFA) and pure Ag-coated PI (PA) enhances EM wave absorption and dissipation, achieving ultralow reflectivity. • The fluffy 3D structure of PFA provides thermal insulation, while the low infrared emissivity of PA ensures excellent infrared stealth performance. • Strong interfacial bonding between Fe3O4, Ag, and PI fibers ensures thermal stability, making the material promising for military tent applications.
Abstract
Designing and fabricating a compatible low-reflectivity electromagnetic interference (EMI) shielding/high-temperature resistant infrared stealth material possesses a critical significance in the field of military. Hence, a hierarchical polyimide (PI) nonwoven fabric is fabricated by alkali treatment, in-situ growth of magnetic particles and "self-activated" electroless Ag plating process. Especially, the hierarchical impedance matching can be constructed by systematically assembling Fe3O4/Ag-loaded PI nonwoven fabric (PFA) and pure Ag-coated PI nonwoven fabric (PA), endowing it with an ultralow-reflectivity EMI shielding performance. In addition, thermal insulation of fluffy three-dimensional (3D) space structure in PFA and low infrared emissivity of PA originated from Ag plating bring an excellent infrared stealth performance. More importantly, the strong bonding interaction between Fe3O4, Ag, and PI fiber improves thermal stability in EMI shielding and high-temperature resistant infrared stealth performance. Such excellent comprehensive performance makes it promising for military tents to protect internal equipment from electromagnetic interference stemmed from adjacent equipment and/or enemy, and inhibit external infrared detection.
1. Introduction
As the electronics and information industry rapidly develops, electromagnetic leakage and high-temperature infrared radiation become serious problems [1, 2]. Especially in the field of military protection, they easily lead to the information leakage and infrared exposure [3–6]. Hence, designing and fabricating compatible electromagnetic interference (EMI) shielding and infrared stealth material possesses a significant application value [2, 7, 8]. In comparison with those traditional metal and carbon-based nanomaterials, polymer-based composites attract increasing attention for EMI shielding and infrared stealth application, due to low density, corrosion resistance, low weight, and good processability [9–13].
Among them, metallized polymer nonwoven fabric gradually becomes a promising electromagnetic protection material, owning to its ultralight density, excellent flexibility, high electrical conductivity, and low infrared emissivity [14–17]. As reported [14], nickel-metallized polyimide nonwoven fabric is prepared by polydopamine roughening, palladium-free activation of chloroplatinic acid, electroless nickel plating, and octadecanethiol corrosion-resistant treatment. It exhibits a high electromagnetic interference shielding effectiveness (EMI SE) value of 68.6 dB, due to their high electrical conductivity (953 S cm−1). However, its higher electrical conductivity usually leads to the generation of impedance mismatch on interface between material and air. Most of incident electromagnetic waves (EMWs) are reflected to the original medium. As a result, the reflected EMWs are prone to induce a secondary pollution, severely interfering the normal operation of adjacent electronic devices. Meanwhile, the introduction of metal coating endows the composite with an excellent thermal conductivity. The higher thermal conductivity transmits lots of heat energy derived from self-heating electrical equipment, thereby inducing the formation of obvious infrared radiation. The undesired infrared radiation is easily detected by infrared detectors. Therefore, how to realize the synergistic design and fabrication of compatible composites with low-reflectivity EMI shielding and infrared stealth performance gradually becomes a big challenge in the system.
Loading authentic research manuscript (Pages 1–5)...
Xinwei Tang, Yezi Lu, Shuangshuang Li, Mingyang Zhu, Zixuan Wang, Yan Li, Zaiyin Hu, Penglun Zheng, Zicheng Wang, Tianxi Liu (2024). Hierarchical Polyimide Nonwoven Fabric with Ultralow-Reflectivity Electromagnetic Interference Shielding and High-Temperature Resistant Infrared Stealth Performance. Nano-Micro Letters. https://doi.org/10.1007/s40820-024-01590-3
Research & Educational Purpose Only:The translations, structured abstracts, analytical annotations, and data reports provided by SinoTechIntel are intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoTechIntel claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What is the main achievement of this research?
The research successfully fabricates a hierarchical polyimide nonwoven fabric with ultralow-reflectivity electromagnetic interference shielding and high-temperature resistant infrared stealth performance, achieved through alkali treatment, in-situ growth of magnetic particles, and self-activated electroless Ag plating.
How does the material achieve low reflectivity in EMI shielding?
The material achieves low reflectivity by constructing a hierarchical impedance matching structure through assembling Fe3O4/Ag-loaded PI nonwoven fabric (PFA) and pure Ag-coated PI nonwoven fabric (PA), which allows more electromagnetic waves to enter and be dissipated rather than reflected.
What makes the material suitable for high-temperature infrared stealth?
The fluffy 3D space structure of PFA provides thermal insulation, while the low infrared emissivity of PA, originating from Ag plating, ensures excellent infrared stealth performance even at high temperatures.
What are the potential applications of this material?
The material is promising for military tents to protect internal equipment from electromagnetic interference and to inhibit external infrared detection, due to its combined EMI shielding and infrared stealth capabilities.
How is the thermal stability of the material ensured?
The strong bonding interaction between Fe3O4, Ag, and PI fibers improves the thermal stability of the material, maintaining its EMI shielding and infrared stealth performance at high temperatures.
Related Technical Papers & Translations
Direct Repair of the Crystal Structure and Coating Surface of Spent LiFePO4 Materials Enables Superfast Li-Ion Migration
The rapid accumulation of spent LiFePO4 (LFP) cathodes from retired lithium-ion batteries necessitates the development of effective and environmental-friendly recycling strategies. In this context, direct regeneration has emerged as a promising approach for reclaiming LFP cathode materials, offering a streamlined pathway to restore their electrochemical functionality. We report an integrated regeneration protocol that simultaneously repairs the degraded crystal structure and reconstructs the damaged carbon coating in spent LFP. The regenerated cathode material had superfast lithium-ion diffusion kinetics and a stable cathode–electrolyte interface, giving a remarkable rate capability with specific capacities of 122 mAh g−1 at 5C and 106 mAh g−1 at 10C (1C = 170 mA g−1). It also maintained capacities of 110.7 mAh g−1 (5C) and 84.1 mAh g−1 (10C) after 400 cycles. It could be used in harsh environments and could be stably cycled at subzero temperatures (−10 and −20 °C) and in solid-state electrolyte batteries. Life cycle assessment combined with economic evaluation using the EverBatt model reveals that this direct regeneration approach has high economic and environmental benefits.
Oxide Semiconductor for Advanced Memory Architectures: Atomic Layer Deposition, Key Requirement and Challenges
Oxide semiconductors (OSs), introduced by the Hosono group in the early 2000s, have evolved from display backplane materials to promising candidates for advanced memory and logic devices. The exceptionally low leakage current of OSs and compatibility with three-dimensional (3D) architectures have recently sparked renewed interest in their use in semiconductor applications. This review begins by exploring the unique material properties of OSs, which fundamentally originate from their distinct electronic band structure. Subsequently, we focus on atomic layer deposition (ALD), a core technique for growing excellent OS films, covering both basic and advanced processes compatible with 3D scaling. The basic surface reaction mechanisms—adsorption and reaction—and their roles in film growth are introduced. Furthermore, material design strategies, such as cation selection, crystallinity control, anion doping, and heterostructure engineering, are discussed. We also highlight challenges in memory applications, including contact resistance, hydrogen instability, and lack of p-type materials, and discuss the feasibility of ALD-grown OSs as potential solutions. Lastly, we provide an outlook on the role of ALD-grown OSs in memory technologies. This review bridges material fundamentals and device-level requirements, offering a comprehensive perspective on the potential of ALD-driven OSs for next-generation semiconductor memory devices.
Laser powder bed fusion of biodegradable Zn-4Cu alloy: Processing, microstructure and properties
Zn's natural degradability and biocompatibility make it a promising candidate for implants, however, its mechanical properties remain insufficient for bone applications. In this study, the performance of Zn was enhanced by developing Zn-Cu alloys via laser powder bed fusion (LPBF). Optimal LPBF parameters for forming stable tracks were achieved by adjusting laser power and scanning speed. Under optimized conditions of 100 W and 100 mm/s, high-density (99.58%) Zn-Cu alloys with improved hardness (68.2HV) and yield strength (160 MPa) were achieved. These improvements are attributed to solid solution strengthening, segregation strengthening, and grain refinement. The Zn-Cu alloys also demonstrated favorable degradation behavior, with a rate of 0.16 mm/year. This degradation is primarily driven by micro-galvanic corrosion between the CuZn5 phase and Zn matrix, along with refined grains and increased grain boundary density. This work demonstrates a viable strategy for fabricating Zn-based implants with enhanced structural integrity and mechanical performance via LPBF.