&Ldquo; Lisa, look, there are so many scratches on my product. Is there a problem with the metallographic sandpaper& Rdquo; Every time I hear a user raise this question, I know that the sample has too many scratches and the metallographic sandpaper is backing up! Here, I will share some of the experience I have accumulated in my work with friends and share it with you to uncover the truth!


Metallographic sample polishing is the process of obtaining accurate data for metallographic analysis by using mechanical or chemical-mechanical polishing methods to ensure a good flatness of the sample surface and retain its true organizational structure. The consumables used in the grinding and polishing process, such as grinding discs, metallographic sandpaper, polishing fluid, polishing cloth, polishing paste, etc., may cause many scratches and defects if not selected properly or not cleaned properly during the operation.

There are too many scratches on the sample. In summary, there are approximately three aspects:


1、 In the fine polishing stage, if there are too many scratches on the surface of the sample that cannot be removed, the problem may be related to the quality of the metallographic sandpaper. The finer the particle size of the metallographic sandpaper, the higher the quality requirements. It is necessary to choose a brand of guaranteed and high-quality metallographic sandpaper.


In addition, the more likely cause of excessive scratches is cross contamination. Therefore, it is particularly important to thoroughly rinse the surface of the sample, fixture, and grinding disc before entering the next polishing process. Rinse with water for an additional period of time to remove residual grinding medium particles from the previous process, effectively reducing cross contamination, and thus avoiding scratches.


2、 When grinding and polishing porous or cracked metallographic samples, if ultrasonic cleaning can be used, it is a good method to avoid secondary scratches caused by residual particles. However, the time required for ultrasonic cleaning should not be too long, as there may be a risk of damage to the sample.


3、 There is also a situation where adding polishing solution 30 seconds before the end of fine polishing of the sample may cause scratches to occur again. Therefore, it is recommended not to add polishing solution within 30 seconds before the end of polishing. And after polishing is completed, the surface of the polishing cloth and sample should be thoroughly rinsed with flowing water.

The problem of excessive scratches can be effectively solved by addressing it from the three aspects mentioned above. Therefore, if there are too many scratches on the sample again, the metallographic sandpaper should not be left behind. It is necessary to conduct in-depth observation and analysis, find the cause through experiments, and apply the right medicine to the case, in order to obtain a better solution. If the above methods still cannot solve your problem, please consult with an engineer from Kemai Testing. We will be able to help you find the truth, solve the problem in a timely manner, and successfully complete the sample preparation task.