Carbon–fibre epoxy composites are widely used for high-performance structural applications, where they are often exposed to harsh environments. The result of moisture ingress has been extensively studied, causing significant deterioration in the mechanical properties of these composites. This study evaluates the performance of five commercial hydrophobic coatings as protective layers, to inhibit moisture ingress into the composite. The coatings evaluated were NeverWet, HydroBead, SHC, Aculon and LiquidGlass. These coatings were characterised and compared in terms of hydrophobicity, surface energy, roughness and chemical composition. This study also evaluated two atmospheric plasma pre-treatments as a means of enhancing the adhesion performance of these coatings. The pre-treatments involved the use of an air plasma for the activation of the epoxy, as well as the plasma deposition of a nanometre thick SiOx interlayer coating. The durability and protective performance of the coatings, with and without the pre-treatments were then compared using an abrasion test as well as a water immersion study. The use of both plasma pre-treatments was found to enhance the adhesion and the abrasion performance of four out of the five coatings. Of the coatings and pre-treatments investigated, the LiquidGlass in conjunction with a SiOx-coating interlayer was found to exhibit the highest abrasion resistance. This was followed by the composite, which was plasma activated prior to the application of the Aculon coating. Only minor differences were observed when comparing the total moisture ingress (M%) of the epoxy, coated with the different hydrophobic layers. The composite coated with the Aculon and SiOx interlayer exhibited the least amount of moisture ingress, at 0.90%, compared to 1.08% of the uncoated specimen. The shear strength of epoxy composite, coated with the LiquidGlass, NeverWet and the activated Aculon combination, were within the range of the uncoated specimens, therefore the moisture ingress was reversible upon heating and no permanent damage to the epoxy–fibre interface was observed. It is concluded that, of the five coatings investigated, both the Aculon coating and LiquidGlass in combination with a SiOx interlayer coating, exhibit the greatest potential as protective layers for carbon fibre epoxy composites.

中文翻译：

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碳纤维环氧复合材料疏水涂层保护性能评价

碳纤维环氧复合材料广泛用于高性能结构应用，在这些应用中它们经常暴露在恶劣的环境中。水分进入的结果已被广泛研究，导致这些复合材料的机械性能显着恶化。本研究评估了五种商用疏水涂层作为保护层的性能，以抑制湿气进入复合材料。评估的涂层是 NeverWet、HydroBead、SHC、Aculon 和 LiquidGlass。这些涂层在疏水性、表面能、粗糙度和化学成分方面进行了表征和比较。该研究还评估了两种常压等离子预处理作为提高这些涂层附着性能的一种手段。预处理包括使用空气等离子体激活环氧树脂，以及纳米厚 SiOx 夹层涂层的等离子体沉积。然后使用磨损试验和水浸研究比较了经过和不经过预处理的涂层的耐久性和保护性能。发现使用两种等离子体预处理可以增强五种涂层中四种涂层的附着力和耐磨性能。在所研究的涂层和预处理中，发现 LiquidGlass 与 SiOx 涂层夹层一起表现出最高的耐磨性。紧接着是复合材料，在应用 Aculon 涂层之前对其进行了等离子体活化。在比较涂有不同疏水层的环氧树脂的总水分进入量 (M%) 时，仅观察到微小的差异。与未涂层样品的 1.08% 相比，涂有 Aculon 和 SiOx 夹层的复合材料表现出最少的水分进入量，为 0.90%。涂有 LiquidGlass、NeverWet 和活化 Aculon 组合的环氧复合材料的剪切强度在未涂层样品的范围内，因此水分进入在加热时是可逆的，并且没有观察到对环氧树脂 - 纤维界面的永久性损坏。得出的结论是，在所研究的五种涂层中，Aculon 涂层和 LiquidGlass 与 SiOx 夹层涂层的组合作为碳纤维环氧复合材料的保护层表现出最大的潜力。NeverWet 和活化的 Aculon 组合在未涂层样品的范围内，因此加热后水分进入是可逆的，并且没有观察到对环氧树脂-纤维界面的永久性损坏。得出的结论是，在所研究的五种涂层中，Aculon 涂层和 LiquidGlass 与 SiOx 夹层涂层的组合作为碳纤维环氧复合材料的保护层表现出最大的潜力。NeverWet 和活化的 Aculon 组合在未涂层样品的范围内，因此加热后水分进入是可逆的，并且没有观察到对环氧树脂-纤维界面的永久性损坏。得出的结论是，在所研究的五种涂层中，Aculon 涂层和 LiquidGlass 与 SiOx 夹层涂层的组合作为碳纤维环氧复合材料的保护层表现出最大的潜力。