Development of Scanning Interfacial Impedance Measuring Apparatus.

Research Project

Project/Area Number	63850153
Research Category	Grant-in-Aid for Developmental Scientific Research
Allocation Type	Single-year Grants
Research Field	金属材料(含表面処理・腐食防食)
Research Institution	OSAKA UNIVERSITY
Principal Investigator	SHIBATA Toshio FACULTY OF ENGINEERING PROFESSOR, 工学部, 教授 (90001205)
Co-Investigator(Kenkyū-buntansha)	KANAI Hajime NF CORPORATION DIRECTOR, 技術担当常務取締役 TAKAMURA Hisao NISSHIN STEEL CO., LTD R & D LABORATORY FOR NEW MATERIALS. GENERAL MANAGER, 新材料研究所, 副所長 FUJIMOTO Shinji FACULTY OF ENGINEERING RESEARCH ASSOCIATE, 工学部, 助手 (70199371) TANIGUCH Shigeji FACULTY OF ENGINEERING ASSOCIATE PROFESSOR, 工学部, 助教授 (50029196)
Project Period (FY)	1988 – 1989
Project Status	Completed (Fiscal Year 1989)
Budget Amount *help	¥9,200,000 (Direct Cost: ¥9,200,000) Fiscal Year 1989: ¥2,700,000 (Direct Cost: ¥2,700,000) Fiscal Year 1988: ¥6,500,000 (Direct Cost: ¥6,500,000)
Keywords	Electrochemical impedance / Scanning impedance measurement / Two dimensional impedance map / Evaluation for defects in coating film / 走査界面インピーダンス測定 / 微小インピーダンスプローブ / 耐食性皮膜 / 欠陥評価
Research Abstract	Many kinds of characterization methods have been proposed for coating and surface files. Among them, electrochemical impedance spectrometry have been widely used not only for basic research, but also for industrial applications, because it could measure film properties without destruction. The above method, however, could obtain a mean or average value over the surface which was measured, so that information on defects and its distribution in the film or localized degradated area could not be obtained. In this study, "Scanning Interfacial impedance Measuring Apparatus" is aimed to develop by using a micro-probe which is seamed over the surface, and to make two dimensional impedance maps for identifying defects in coating files with corrosion rate and their distributions. In 1988, a main part of the apparatus which consists of X-Y-Z stage, frequency response analyzer, and potentiostat had been constructed. In 1989, a personal computer was purchased ard was used to control the apparatus, to make acquisition of the data, and finally to display impedance maps in a CRT screen or printer. A newly developed micro-probe which includes a counter electrode and a reference electrode within a thin tube was developed and succeeded to measure impedance maps with enough resolution. The resolution for distinguishing two points was proved to be about 200 mum. Defects and their distributions in coating film on steel in accelerated environments was characterized quantitatively. The process of degradation of the film was also evaluated. Poison distribution was observed and the distribution of the highest degradated sites was found to obey the Gumbel distribution.