The Agglutinative-Bonding-Performance Study of Chromic Acid, Sulfuric Acid And Hard Anodizing AA 7075 under Salt Spray Environment

• Main Authors: Chi-An Tung, 董騏銨
• Other Authors: Chao-Sheng Chou
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/19184889150069001749

碩士 === 義守大學 === 材料科學與工程學系碩士班 === 96 === The lap shear tensile strength (LSTS) and failure mode analysis of epoxy resin (FM1000) bonded 7075-T6 aluminum alloy specimens with chromic acid anodizing, sulfuric acid anodizing and hard anodizing were investigated espectively. The effects of salt spray environment on the shear bonding strength were also discussed. The lap shear tensile strength tests were implemented per ASTM D1002 (Single-lap-joint adhesively bonded metal specimens by tension loading metal-to-metal). Experimental results showed that chromic acid anodizing specimens exhibited the highest shear bonding strength at room temperature. After salt spray tests 168hr and 336hr per ASTM B117, chromic acid anodizing specimens still exhibited the highest shear bonding strength, event thought their strength decay were the most significant. We also used indentation and bending tests to observe the deformation and fracture mode of the three kinds of anodizing coatings. Opening mode fracture was dominated in chromic acid anodizing coating and sulfuric acid anodizing coating. In hard anodizing coating, both opening and sliding mode fractures were observed. Sulfuric acid anodizing coating also showed the largest cracking area and chromic acid anodizing coating showed the smallest cracking area. Chromic acid anodizing coating constantly showed the best bonding performance comparing with sulfuric acid anodizing and hard anodizing in atmosphere and salt spray environment. The good bonding performance of chromic acid anodizing coating may be attributed to their better fracture toughness due to thinnest coating. Therefore, chromic acid anodizing process is very suitable for agglutinative components of aircraft. Sulfuric acid anodizing process will have the better corrosion-resistant performance.