Development of NDE Apparatus for Dry/Wet Surface Defects with Photo acoustic and Photo thermal effects.

在本研究项目中，我们注意到光热电化学（PE）检测是基于激光束对电化学反应的积累和调制，因此最需要考虑的是提高再现性。1998学年，采用三端（3T）法代替两端（2T）法。在3T方案中，为了稳定阴极和阳极之间的电位，在阴极和阳极之间增加了一个参比电极。因此，3T方法提高了PE信号的再现性。进一步验证了点蚀孔的化学腐蚀是累积的，从而产生了PE信号。然而，另一方面，如果施加在参考电极上的电压略低于金属试样的腐蚀电位，则其余金属试样几乎不会发生化学反应而产生点蚀。同样的表面缺陷用PA法进行了测量。结果表明，PE方法在空间分辨率上与PA方法相当。Hiwatashi研究小组试图制造实际的点蚀，并用PAM进行测量。恩多课题组用聚丙烯酰胺对金属板的实际裂纹进行了测量，他们的工作在聚丙烯酰胺作为无损检测的实际应用方面取得了进展。1999学年，通过Lab VIEW软件控制的精细滑动台的实际应用，PAM得到了显著的发展。上述研究成果已在国内外会议（SPIE, Yokohama/IEEE, Nevada）上发表。如上所述，在本研究项目中，由首席研究员提出的一种新的PE方法被证明是一种新的工具，它能够测量电解质液体环境中小型分布管中发生的腐蚀或微小的点孔，而传统的气体麦克风PA方法无法应用于此。此外，还设计了PAM的驱动系统，实现了PAM在实际无损检测中的应用。少

In this research project, we paid an attention to the fact that a photothermal electrochemical (PE) detection is based on the accumulation and modulation of a electrochemical reaction by the laser beam so that the improvement of the reproducibility was most considered. In the academic year 1998, three-terminal (3T) method was adopted instead of two-terminal (2T) method. In the 3T scheme, a reference electrode was added between cathode and anode in order to stabilize a potential between cathode and anode. As a result, 3T method improves the reproducibility of the PE signal. Furthermore, it was verified that the chemical etching of the pitting corrosion hole was accumulated so that it generated a PE signal. On the other hand, however, the rest metal specimen was almost kept without pitting by chemical reaction, if the voltage applied to the reference electrode was adjusted slightly below the corrosion potential of the metal specimen. The same surface defect was measured by PA method for … More comparison. The result showed that the PE method was comparable to PA method in spatial resolution. Group of investigator Hiwatashi tried to made actual pitting corrosions and measured them with PAM.. Group of investigator Endoh measured actual cracks occurred in a metal plate with PAM..Their works made advance in NDE with PAM as actual applications.In the academic year 1999, remarkable development of PAM was by the practical use of fine slide stages controlled by the software Lab VIEW. The above research results were presented at the domestic and international conferences (SPIE, Yokohama/IEEE, Nevada).As described above, in this research project, a new PE method, which was proposed by the head investigator, was shown to be a new tool, which is capable to measure corrosions or tiny pitting holes occurred in small distributing pipes in an electrolyte liquid environment, in which a conventional gas-microphone PA method was unable to be applied. Furthermore, driving system of PAM was also done so that applications of the PAM to actual NDE was realized. Less