{"title":"7075-T6铝合金翼板的腐蚀","authors":"","doi":"10.31399/asm.fach.aero.c0006402","DOIUrl":null,"url":null,"abstract":"\n New aircraft wing panels extruded from 7075-T6 aluminum exhibited an unusual pattern of circular black interrupted lines, which could not be removed by scouring or light sanding. The panels, subsequent to profiling and machining, were required to be penetrated inspected, shot peened, H2SO4 anodized, and coated with MIL-C-27725 integral fuel tank coating on the rib side. Scanning electron microscopy and microprobe analysis (both conventional energy-dispersive and Auger analyzers) showed that the anodic coating was applied over an improperly cleaned and contaminated surface. The expanding corrosion product had cracked and, in some places, had flaked away the anodized coating. The corrodent had penetrated the base aluminum in the form of subsurface intergranular attack to a depth of 0.035 mm (0.0014 in.). It was recommended that a vapor degreaser be used during cleaning prior to anodizing. A hot inhibited alkaline cleaner was also recommended during cleaning prior to anodizing. The panels should be dichromate sealed after anodizing. The use of deionized water was also recommended during the dichromate sealing operation. In addition, the use of an epoxy primer prior to shipment of the panels was endorsed. Most importantly, surveillance of the anodizing process itself was emphasized.","PeriodicalId":326464,"journal":{"name":"ASM Failure Analysis Case Histories: Air and Spacecraft","volume":"27 1","pages":"0"},"PeriodicalIF":0.0000,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Corrosion of Aluminum Alloy 7075-T6 Wing Panel\",\"authors\":\"\",\"doi\":\"10.31399/asm.fach.aero.c0006402\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"\\n New aircraft wing panels extruded from 7075-T6 aluminum exhibited an unusual pattern of circular black interrupted lines, which could not be removed by scouring or light sanding. The panels, subsequent to profiling and machining, were required to be penetrated inspected, shot peened, H2SO4 anodized, and coated with MIL-C-27725 integral fuel tank coating on the rib side. Scanning electron microscopy and microprobe analysis (both conventional energy-dispersive and Auger analyzers) showed that the anodic coating was applied over an improperly cleaned and contaminated surface. The expanding corrosion product had cracked and, in some places, had flaked away the anodized coating. The corrodent had penetrated the base aluminum in the form of subsurface intergranular attack to a depth of 0.035 mm (0.0014 in.). It was recommended that a vapor degreaser be used during cleaning prior to anodizing. A hot inhibited alkaline cleaner was also recommended during cleaning prior to anodizing. The panels should be dichromate sealed after anodizing. The use of deionized water was also recommended during the dichromate sealing operation. In addition, the use of an epoxy primer prior to shipment of the panels was endorsed. Most importantly, surveillance of the anodizing process itself was emphasized.\",\"PeriodicalId\":326464,\"journal\":{\"name\":\"ASM Failure Analysis Case Histories: Air and Spacecraft\",\"volume\":\"27 1\",\"pages\":\"0\"},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2019-06-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"ASM Failure Analysis Case Histories: Air and Spacecraft\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.31399/asm.fach.aero.c0006402\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"ASM Failure Analysis Case Histories: Air and Spacecraft","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.31399/asm.fach.aero.c0006402","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
摘要
由7075-T6铝材挤压而成的新飞机机翼面板显示出一种不寻常的圆形黑色断线图案,这种图案无法通过冲刷或光砂去除。在成型和加工之后,面板需要进行穿透检查、喷丸处理、H2SO4阳极氧化,并在肋侧涂上MIL-C-27725整体油箱涂层。扫描电子显微镜和微探针分析(包括传统的能量色散和俄歇分析仪)表明,阳极涂层被应用在不正确清洁和污染的表面上。膨胀的腐蚀产物已经破裂,在某些地方,阳极氧化涂层已经剥落。腐蚀以表面下晶间侵蚀的形式渗入基体铝,深度为0.035 mm (0.0014 in.)。建议在阳极氧化前的清洁过程中使用蒸汽脱脂剂。在阳极氧化之前的清洁过程中,也建议使用热抑制碱性清洁剂。阳极氧化后的面板应采用重铬酸盐密封。在重铬酸盐密封过程中也建议使用去离子水。此外,批准在面板装运前使用环氧底漆。最重要的是,强调了对阳极氧化过程本身的监测。
New aircraft wing panels extruded from 7075-T6 aluminum exhibited an unusual pattern of circular black interrupted lines, which could not be removed by scouring or light sanding. The panels, subsequent to profiling and machining, were required to be penetrated inspected, shot peened, H2SO4 anodized, and coated with MIL-C-27725 integral fuel tank coating on the rib side. Scanning electron microscopy and microprobe analysis (both conventional energy-dispersive and Auger analyzers) showed that the anodic coating was applied over an improperly cleaned and contaminated surface. The expanding corrosion product had cracked and, in some places, had flaked away the anodized coating. The corrodent had penetrated the base aluminum in the form of subsurface intergranular attack to a depth of 0.035 mm (0.0014 in.). It was recommended that a vapor degreaser be used during cleaning prior to anodizing. A hot inhibited alkaline cleaner was also recommended during cleaning prior to anodizing. The panels should be dichromate sealed after anodizing. The use of deionized water was also recommended during the dichromate sealing operation. In addition, the use of an epoxy primer prior to shipment of the panels was endorsed. Most importantly, surveillance of the anodizing process itself was emphasized.