铬含量对铁基涂层抗高温氧化性能的影响

Investigation of Chromium Content on Elevated Oxidation Resistance of Iron-based Coating

采用电弧喷涂技术制备四种铁基抗高温氧化涂层。将涂层加热到800℃进行240h高温氧化实验。采用扫描电镜、X射线衍射仪对涂层氧化产物的形貌、成分和相组成进行分析。结果表明:铬含量对铁基合金涂层的抗高温氧化性能有显著的影响,当铬含量大于40%(质量分数,下同)时,涂层表面生成了连续的Cr2O3保护膜,涂层具有良好的抗高温氧化性能。铬含量(<30%)较低的涂层,涂层表面只能生成少量尖晶石结构的氧化物FeCr2O4,对基体有一定的保护,但其氧化产物大部分是Fe2O3,组织结构疏松,容易脱落,保护性能较差。

Four kinds of high temperature oxidation resistant iron-based coatings were prepared by arc spraying process. Oxidation experiments of these coatings were carried out at 800℃ in air for up to 240h. The morphologies, composition, and phase structures of the oxidation products were investigated using scanning electron microscopy （SEM） and X-ray diffraction analysis （XRD）. The results show that the Cr content plays an important role in the oxidation resistance. When the Cr content contained in the coating is more than 40%（mass fraction）, a continuous Cr2O3 passivation layer is developed on the surface of the coating, leading to good high temperature oxidation resistance. In the low Cr-containing coating, e. g. , lower than 30 %, only a small quantity of spinel structured FeCr2O4 was formed on the surface of the coating, which provides protection to the suhstrate. However, most of the oxidation products are loose structured Fe2O3, and are easy to spall off, resulting in a poor effect in substrate protection.