Corrosion-related interfacial defects formed by dissolution of aluminum in aqueo

2019-12-18 19:40:41

surface etching oxide pits voids

责任者: Huiquan Wu;Hebert, K.R.;Gessmann, T.;Lynn, K.G. 单位: Dept. of Chem. Eng., Iowa State Univ., Ames, IA, USA 来源出处: Journal of the Electrochemical Society(J. Electrochem. Soc. (USA)),2002/04/,149(4):108-16 摘要: The mechanism was investigated by which pit initiation on aluminum foils during anodic etching is affected by the use of phosphoric acid as a pretreatment. Positron annihilation measurements, coupled with atomic force microscope images of foils with chemically stripped oxide layers, show evidence that the pretreatment introduces nanometer-scale voids in the metal, at or near the metal-oxide film interface. The location and morphology of voids compares favorably with those of pits, suggesting that voids act as pit initiation sites. The number of void sites was estimated to be 107 cm-2, the same magnitude as the maximum number of pits formed by anodic etching. Capacitance measurements further indicate that the treatment decreases the surface oxide thickness to about 2 nm. Formation of large numbers of pits during etching is promoted by either reduced oxide thicknesses or more positive etching potentials. It is suggested that the rate of initiation of pits at interfacial voids is determined by the electric field in the overlying surface oxide 关键词: aluminium;anodisation;atomic force microscopy;corrosion;etching;positron annihilation;surface composition;surface structure;voids (solid);corrosion-related interfacial defects;dissolution;aqueous phosphoric acid;Al foils;anodic etching;positron annihilation;atomic force microscope images;chemically stripped oxide layers;nanometer-scale voids;location;morphology;pit initiation sites;positive etching potentials;overlying surface oxide;2 nm;Al;H3PO4