表面技术2025，Vol.54Issue(12)：105-113,9.DOI:10.16490/j.cnki.issn.1001-3660.2025.12.009
利用阵列差分涡流检测对铝合金涂层下腐蚀无损成像检测研究
Non-destructive Imaging of Corrosion under Aluminium Alloy Coatings with Array Differential Eddy Current Detection
摘要
Abstract
Aluminium alloys are widely used in aerospace,automotive,machinery,electronic information and other fields because of their low density,high strength,corrosion resistance,easy processing and other performance characteristics.Although the aluminium alloy has a certain corrosion resistance,but in some harsh environments(such as the sea),it is necessary to coat the aluminium alloy to protect its surface,ensuring the safe use of aluminium alloy components.However,the aging of the coating will result in a gradual decrease in the protective ability,and before the coating completely fails,corrosion has already occurred under the intact appearance of the coating,which cannot be detected by naked eyes,posing a serious potential risk.Traditionally,the maintenance method of periodic coating removal is generally used to detect corrosion damage under the coating,but there are disadvantages of high cost and low efficiency,and there is the potential danger of untimely repair.Therefore,there is an increasing demand for non-destructive testing of corrosion damage under the coating,especially for non-destructive visual inspection that can be performed quickly and efficiently. The work aims to investigate the potential use of an array differential eddy current detection for non-destructive imaging detection of corrosion under aluminium alloy coatings.2A12-T4 aluminium alloy widely used in aerospace industry,coated with acrylic coating was used as the research object,and damage samples with different levels of corrosion were obtained by accelerated corrosion experiments in hydrochloric acid solution for different time,followed by the array eddy current detection.After the detection,the coatings were removed with a paint stripper,and the corrosion defects under the coatings were characterized in terms of microscopic morphology,chemical composition and three-dimensional dimensions by scanning electron microscope,energy dispersive X-ray detector and white-light interferometer,respectively.The correlation law between corrosion defect dimensions and differential eddy current signals was obtained.The effect mechanism of the corrosion defect size on the differential eddy current signal was also investigated through finite element analysis. It was found that the corrosion damage of the aluminium alloy under the coating presented shallow disc-type geometrical characteristics,which grew mainly in the depth direction at the early stage of corrosion,and grew in both radial and depth directions at the late stage of corrosion.The larger the size of the corrosion defect under the coating,the stronger the detection signal.This is because there is no eddy current distribution at the corrosion defect due to the corrosion of the aluminium alloy that is conductive,so the coil located above the defect has a small eddy current density,leading to smaller impedance value,while if the defect is larger,the larger the difference in eddy current density between the coils,the stronger the differential signal.In the scanning direction,the defect is almost in the same straight line of the coil compared to other coils,which can reach the highest degree of coincidence with the defect.At this time,due to its differential signal coil and the defect of the lowest degree of coincidence,the detection signal obtained is the strongest.The coils on both sides due to the gradual decrease in the degree of coincidence with the corrosion defects result in a gradual decline in the intensity of the signal.Corrosion damage occurs in the region of the array eddy current differential signal,presenting a 'concave-convex' signal characteristics,and the actual location of the defect is in the detection signal between the'peak'and'valley'.The existence of corrosion defects under the coating can be determined intuitively,and the eddy current imaging detection of corrosion defects can be realized.关键词
铝合金/腐蚀/涂层/涡流/无损检测/有限元分析Key words
aluminum alloy/corrosion/coating/eddy current/non-destructive testing/finite element analysis分类
矿业与冶金引用本文复制引用
唐孝良,舒畅,潘茂林,王忠维,周俊,简光建,邓庆祝,莫少览,邓江,佘祖新,钟勇,黄伦..利用阵列差分涡流检测对铝合金涂层下腐蚀无损成像检测研究[J].表面技术,2025,54(12):105-113,9.基金项目
成都市区域科技创新合作项目(2023-YF11-00021-HZ)Chengdu Regional Science and Technology Innovation Cooperation Project(2023-YF11-00021-HZ) （2023-YF11-00021-HZ）
