Development of a New Lubricant Analysis Technique for Plant Facilities Using Terahertz Electromagnetic Wave Measurements

Abstract

In this study, basic research was conducted on a new lubricant analysis technique to constantly monitor the deterioration state of rotating equipment and other components in plant facilities. The research method used terahertz electromagnetic waves, which are electromagnetic waves in the frequency range of 0.1 to 10 THz, the boundary region between light and radio waves. As a measurement method, we focused on the fact that terahertz electromagnetic waves are safe for the human body yet have excellent transmittance, and conducted experiments using terahertz time-domain spectroscopy (THz-TDS). In this study, THz-TDS measurements were performed on artificially degraded lubricating oil to verify the possibility of detecting degradation factors and separately identifying each degradation factor. As a result, it was possible to detect water and iron powder and to identify them separately using the transmittance of THz electromagnetic waves obtained from the obtained time waveforms and the standard deviation ratio of the peak intensity values of THz waveforms. In addition, the detection and separation of iron powder, water, and antioxidants were possible using the attenuation of terahertz electromagnetic waves obtained from the frequency waveforms obtained by Fourier transforming the time waveforms. These results suggest that terahertz electromagnetic waves can be used to detect iron powder, water, and antioxidants, which are factors involved in lubricant degradation, and that each degradation factor can be separated and identified by using terahertz electromagnetic waves.