Zhang Sheng,Wu Bingjie,Song Bo,Chen Tao,Li Qing,Wu Guangshun,Chen Lei
When a spacecraft works in low earth orbit, PBO fiber/epoxy resin composite as structural material not only has the poor interfacial properties, but also faces the attack of atomic oxygen (AO). To solve the two drawbacks, a PBO fiber hierarchical reinforcement has been fabricated without degrading the fiber by a mussel-inspired "two-step" method based on dopamine (DA) assistant co-deposition and chemical grafting technologies. The surface wettability, roughness (Ra) and reactivity of the obtained PBO@PDA-Si-GO are increased significantly in comparison with those of untreated one. The reinforcement offered simultaneously remarkable enhancement in interfacial shear strength (IFSS) and AO erosion resistance of the composites, which laid theoretical and experimental foundations for the realization of the structure/function integration design of advanced composites.
Lei Chen,Gangyan Zhang,Guangshun Wu,Peng Wang,Yuanming Zhang,Minghua Li,Qing Li,Tonghua Zhang
The surface of poly( p -phenylene benzobisoxazole) (PBO) fibers was modified by a hybrid coating composed of polydopamine (PDA) and the hydrolysis products of 3-aminopropyltrimethoxysilane (KH551) using a facile and environment-friendly mussel-inspired co-deposition strategy. The surface morphologies and chemical composition of the obtained hierarchical reinforcement (PBO@PDA/Si) were measured for confirming the successful deposition of the coating. Compared to untreated PBO fiber, the surface roughness and wettability of PBO@PDA/Si were increased remarkably. Importantly, PBO@PDA/Si showed a 50.2% increase in the interfacial shear strength (IFSS) of resulting composite without any decrease in its tensile strength (TS). In addition, its atomic oxygen (AO) erosion and hydrothermal aging resistances were significantly improved. The “one-step” mussel-inspired surface modification strategy starts from simple chemistry and cheap raw materials, and may provide a novel and versatile design for fabricating multifunctional hierarchical reinforcements.
Chi Yan,Jialin Li,Yuhao Dai,ZhiJiang Lan,Haobo Wang,Hua Tong,Xiaojun Ye,Xiao Yuan,Cui Liu,Hongbo Li
Polyimide (PI), commonly used in space applications, is vulnerable to atomic oxygen (AO) erosion in low Earth orbit, causing performance degradation. Atomic layer deposition (ALD) of ultrathin films has great potential as AO protective coatings for aerospace materials. In this study, nanometer-thick plasma-enhanced atomic layer deposition (PEALD) SiO 2 films were deposited on in-situ oxygen plasma-activated PI surfaces. The nucleation and growth process of SiO 2 was systematically analyzed. A uniform and dense SiO 2 film was formed, providing limited resistance to AO erosion, but not sufficient for extreme environmental conditions. To further enhance AO resistance, we introduced thermal ALD-Al 2 O 3 interlayers within the same processing window and alternately deposited conformal, continuous Al 2 O 3 /SiO 2 nanolaminates on the PI surface. The Al 2 O 3 interlayer effectively reduced the film deposition roughness, forming a smoother, denser barrier layer and minimizing growth defects. This dense ALD-Al 2 O 3 /SiO 2 nanolaminate, with its inert Si-O-Al bonds, effectively prevents AO from penetrating the substrate, showing superior protection under long-term AO exposure. After AO irradiation, the surface remained smooth with no obvious defects or voids, effectively avoiding undercutting caused by AO. The synergistic effect of alumina and silica provides excellent AO protection while maintaining good optical transmittance.
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