Microscopic In-situ Evaluation of Corroding Surface of Film

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In this study, the availabilities of Quartz Crystal Microbalance(QCM), Phase Detection Interferometric Microscope (PDIM). Confocal Laser-Scanning Microscope (CLSM), and Scanning Electrochemical Microscope (SECM), which are regarded as powerful methods for microscopic in-situ evaluation of corroding surface of film, are examined more in detail.The frequency analysis of QCM vibration mode has revealed that the apparent decrease in mass of MgCl_2 salt film on gold at a critical relative humidity of 30 % in air results from the decrease in vibrational energy loss of QCM due to the phase transition of MgCl_2 film from solid to liquid which is caused by water absorption into the film, suggesting that QCM is promising as a sensor of phase transition.The PDIM observation of p-type Si surface subjected to chemical etching in HF solution has indicated that the etching rate depends on the specific resistivity of Si and the surface roughness or topography can be evaluated quantitatively as a funct … More ion of etching time. It has been also observed with PDIM that small spots are randomly distributed on electropolished aluminum surface and are associated with defects in the anodic oxide film formed subsequently on the electropolished surface.The application of CLSM to a porous Si layr (PSL) with visible luminescence has succeeded in observing nondestructively the three-dimensional morphology of PSL.The simultaneous measurement of the corresponding luminescensce morphology with CLSM has revealed that the visible luminescence emits uniformly from the whole depth of PSL.The SECM has been applied to evaluate the defect site of anodic oxide film (TiO_2) formed on Ti. When Ti electrode covered with TiO_2 film was immersed in H_2SO_4 solution containing Br^-ions and the potential of the Ti electrode was controlled at the potential of oxidation of Br^-ions, the oxidation of Br^-ions proceeded only on the defect site of TiO_2 film to produce Br_2. Simultaneously, the probe electrode (carbon fiber), the potential of which was controlled at the potential of reduction of Br_2, was scanned just over the Ti electrode surface to measure the distribution map of cathodic current flowed through the probe electrode. The location of defect site of TiO_2 film could be determined from the current distribution map. The application of SECM still continues to evaluate the uniformity of passive film on Fe.The comprehensive understanding of the availabilities of QCM,PDIM,CSLM,and SECM for microscopic in-situ evaluation of corroding surface of film could be performed with the above experimental results. Less