激光熔覆哈氏合金C22涂层在静态和空化酸溶液中的腐蚀行为(英文)

Corrosion behavior of Hastelloy C22 coating produced by laser cladding in static and cavitation acid solution

利用高功率半导体激光器在Q235钢基体上制备哈氏合金C22涂层,研究涂层在静态和空化盐酸、硫酸和硝酸溶液中的腐蚀行为。电化学结果表明:涂层在静态酸溶液中比在空化酸溶液中具有更强的抗腐蚀性能。在以上的每种条件下,涂层抗腐蚀性能由强到弱的顺序均为硝酸、硫酸和盐酸溶液。涂层在空化盐酸溶液中出现冲蚀形貌和严重的晶间腐蚀。这主要与盐酸溶液中存在活性离子以及空化泡崩溃时的力学作用有关。然而,经过空化硝酸溶液腐蚀的涂层表面几乎没有变化。结果表明,空化作用和酸溶液性质的共同作用决定涂层腐蚀的发展。由于在表面形成稳定的致密氧化膜,哈氏合金C22涂层在氧化性酸溶液中表现出更优越的抗腐蚀性能。

The Hastelloy C22 coatings on Q235 steel substrate were produced by high power diode laser cladding technique. Their corrosion behaviors in static and cavitation hydrochloric, sulfuric and nitric acid solutions were investigated. The electrochemical results show that corrosion resistance of coatings in static acid solutions is higher than that in cavitation ones. In each case, coating corrosion resistance in descending order is in nitric, sulfuric and hydrochloric acid solutions. Obvious erosion-corrosion morphology and serious intercrystalline corrosion of coating are noticed in cavitation hydrochloric acid solution. This is mainly ascribed to the aggressive ions in hydrochloric acid solution and mechanical effect from cavitation bubbles collapse. While coating after corrosion test in cavitation nitric acid solution shows nearly unchanged surface morphology. The results indicate that the associated action of cavitation and property of acid solution determines the corrosion development of coating. Hastelloy C22 coating exhibits better corrosion resistance in oxidizing acid solution for the stable formation of dense oxide film on the surface.