Mechanical Properties of Fibers Coated by Atomic Layer Deposition for Polymer-Matrix Composites with Enhanced Thermal and Ultraviolet Resistance

摘要

Interfacial engineering of fiber-reinforced composites is critical to control material properties, such as mechanical strength and toughness. In this study, we utilize atomic layer deposition (ALD) as a method to conformally coat structural fiber surfaces and study the impact of these interlayers on their mechanical adhesion to polymer-matrix materials. ALD of Al_2O_3, ZnO, and TiO_2 were applied to Kevlar~R and carbon fibers, and microbond testing was performed using droplets of PMMA and Epoxy. It was observed that the mechanical force required for debond-ing of the polymer droplet from the coated fiber surfaces depended on the composition and thickness of the coating. Post-mortem scanning electron microscopy and energy dispersive X-ray spectroscopy for elemental analysis indicated that the ALD films remained adhered to the droplet, suggesting that the ALD/fiber interface limited the mechanical properties of the interphase region. Additionally, ALD of ZnO was demonstrated to prevent fiber degradation from ultraviolet (UV) and high-temperature thermal treatments, demonstrating a pathway towards multi-functional composite interphase engineering by ALD.