Post-fire Performance of Wire-arc-Sprayed Zn-15Al Coatings
Post-fire Performance of Wire-arc-Sprayed Zn-15Al Coatings
复制标题
DOI：
10.1007/s11666-023-01577-3
复制
发表时间：
2023-03
影响因子：
3.1
通讯作者：
Ratna Divya Yasoda;Ying Huang;R. Kiran;X. Qi
中科院分区：
文献类型：
--
作者：
Ratna Divya Yasoda;Ying Huang;R. Kiran;X. Qi
电弧喷涂Zn-15 Al涂层用于减轻由于处理易燃产品和野火事件而易受火灾影响的管道、海上平台和桥梁等钢基础设施的腐蚀。过去的研究表明，钢在暴露于高达600 °C的火灾温度时仍能保持其工程性能。因此，本文旨在评估Zn-15 Al防护涂层在火灾事故后的性能。为此目的，在模拟火灾事故的炉中，以100 °C的间隔使涂覆的钢板经受从300 °C到失效的温度。对涂层进行了火灾后微观结构表征、机械完整性测试和电化学研究。当从500 °C冷却时，涂层主要是完整的，这是由于有限的高温氧化以及锌和铝的金属间相的形成，包括共析（α + η）、部分转化的共晶（β + η）和富锌η相。涂层微观结构的这些变化导致涂层的显微硬度和一致的磨损量增加，以及涂层的电化学阻抗增加，与其沉积状态相比，有利于涂层钢构件的可重复使用性。然而，在600 °C下，大量氧化产物的存在增加了涂层的孔隙率，降低了涂层的机械性能。此外，富锌基体与涂层发生分离，并使横截面看起来像镀锌钢，保持防腐蚀能力。当从700 °C暴露冷却时，注意到指示涂层失效的微裂纹，因此当温度超过600 °C时，应更换Zn-15 Al涂层。
Wire-arc-sprayed Zn-15Al coatings are used to mitigate corrosion in steel infrastructure such as pipelines, offshore platforms, and bridges that are susceptible to fire due to the handling of flammable products and wildfire events. Past studies indicate that steel retains its engineering properties when exposed to fire temperatures up to 600 °C. Therefore, this paper aims to assess the performance of Zn-15Al protective coatings after being subjected to a fire accident. For this purpose, coated steel plates were subjected to temperatures ranging from 300 °C to failure at 100 °C intervals in a furnace simulating the fire accidents. Post-fire microstructural characterization, mechanical integrity tests, and electrochemical studies were performed on the coating. The coating was intact primarily when cooled from 500 °C due to limited high-temperature oxidation and formation of intermetallic phases of zinc and aluminum including eutectoid (α + η), partially converted eutectic (β + η) and a zinc-rich η-phase. These changes in the coating microstructure resulted in increased microhardness and consistent wear loss and an increase in the coating’s electrochemical impedance compared to its as-deposited condition favoring the reusability of the coated steel members. However, at 600 °C the presence of large quantities of oxidation products increased the porosity and decreased the mechanical properties of the coating. Furthermore, the separation of the zinc-rich matrix from the coating occurred and made the cross section look like galvanized steel retaining corrosion protection ability. Micro-cracks indicating coating failure were noticed when cooled from 700 °C exposure, and hence the Zn-15Al coatings should be replaced when temperatures exceed 600 °C.