In the fields of industrial manufacturing, electronic components, automotive parts, aerospace, and other fields, the quality of the coating directly affects the performance and service life of the product. As one of the important indicators for measuring the quality of the coating, the choice of measurement method for coating thickness is particularly critical. This article will introduce several commonly used coating thickness measurement methods and briefly analyze their application scope and advantages and disadvantages.



1. Magnetic Coating Thickness Measurement (Magnetic Method)



The magnetic coating thickness measurement method is suitable for measuring the thickness of non-magnetic coatings on ferromagnetic substrates, such as zinc, copper, or paint layers on steel. This method calculates the coating thickness by measuring the change of magnetic flux. Common instruments include magnetic pickup coating thickness gauges and magnetic induction coating thickness gauges. This method is simple to operate, low in cost, and does not require the destruction of the sample, suitable for on-site rapid detection. However, its accuracy is relatively low, sensitive to the magnetic permeability of the substrate material, and therefore not suitable for non-ferromagnetic metal substrates.



2. Eddy Current Coating Thickness Measurement (Eddy Current Method)



The eddy current method is suitable for measuring the thickness of non-conductive coatings on non-magnetic metal substrates, such as coatings on metals such as aluminum and copper. The principle is to use the alternating magnetic field to generate eddy currents in conductors, and then reflect the thickness of the coating through the change of the eddy currents. This method also belongs to non-destructive testing methods, with high measurement accuracy and suitable for thin coatings. However, the equipment price is relatively high, and there are certain requirements for the conductivity and magnetic permeability of the measured materials.



3. X-ray fluorescence coating thickness measurement (XRF)



X-ray fluorescence coating thickness measurement is a non-contact, non-destructive high-precision measurement method, widely used in the measurement of metal coatings such as gold, silver, nickel, and tin. The XRF coating thickness meter can simultaneously measure the thickness and composition of multi-layer coatings, suitable for complex coating structures. This method has high measurement accuracy and good repeatability, but the equipment is expensive and requires high professional knowledge of the operators.



4. Slicing Microscopy (Cross-section Microscopy)



The slicing microscopy method is a destructive measurement method that directly measures the coating thickness by cutting the sample, polishing and polishing it, and then observing it under magnification. This method is suitable for occasions with extremely high precision requirements, such as scientific research and quality arbitration. Although the results are intuitive and accurate, the process is cumbersome, time-consuming, and will damage the sample itself.



5. β-ray backscattering method



The β-ray backscattering method is an advanced technology suitable for online measurement, especially suitable for real-time monitoring of coating thickness on the production line. It calculates the thickness by detecting the scattering of β-rays at the interface between the coating and the substrate. This method can be used for various material combinations, but the equipment is complex and the investment cost is high.



Conclusion



Different types of coatings, base materials, and requirements for measurement accuracy determine the choice of measurement methods. In practical applications, appropriate measurement means should be selected according to specific circumstances to ensure the accuracy and reliability of the measurement results. With the development of science and technology, the measurement of coating thickness in the future will move towards higher accuracy, faster speed, and more functions, providing more powerful support for industrial quality control.