A Review on Defect-level Characterization of Coating Electrodes
The use of coating electrodes in the electrical industry has increased due to their multiple advantages over other types of electrodes. However, coating electrodes are prone to defects due to their complex fabrication process. Defects can weaken the coating layer, affecting its overall conductivity, and eventually reducing its performance. To ensure a high-quality coating electrode and to maximize its performance, it is essential to detect and characterize the presence of any potential defects. Defects on coating electrodes can be classified into three major categories: topography, microstructure and electrical anomalies. This paper reviews the mainly used techniques used to identify and characterize defects on coating electrodes.
Topography defects refer to any irregularities on the coating surface, such as scratches and pinholes. These defects can be easily detected with the aid of optical or scanning electron microscopy. The most common method to quantify these defects is the ASTM D2133-06, which is a systematic method for measuring the size and shape of any surface features. It involves measuring the area and perimeter of each defect with the help of a dedicated software. This method is suitable for determining the size and shape of a defect.
Microstructure defects refer to any defects related to the microstructure of the coating, such as pores, voids, and cracks. These types of defects are difficult to detect using conventional optical tools. To detect microstructure defects, the most commonly used technique is Scanning Acoustic Microscopy (SAM). The technique involves operating sound waves on the sample at different frequencies. The echoes generated due to the interaction of the sound waves are used to generate images of the internal structure of the sample. The images obtained are then used to identify different types of defects on the sample.
Finally, electrical anomalies refer to any differences in electrical properties compared to a reference sample. To detect such defects, the most used technique is Energy Dispersive X-ray Spectroscopy (EDS or EDX). It involves blasting an energetic X-ray beam on the sample and analyzing the X-ray intensity at different points of the sample. This helps to identify any potential differences in the composition or arrangement of elements in the sample as compared to a reference sample.
In conclusion, there are various techniques available to detect and characterize defects on coating electrodes. However, the most suitable technique will depend on the type of defect. For topography defects, optical and scanning electron microscopy are the recommended methods. For microstructure defects, SAM is the most suitable technique, and EDS is suitable for detecting electrical anomalies.
