Several Factors Affecting the Coating Thickness Gauge's Measurement Accuracy
The covering layer formed to protect and decorate the surface of the material, such as coating, plating, coating, sticking layer, chemically formed film, etc., is called coating in relevant national and international standards.
Coating thickness measurement has become an important part of quality inspection in processing industry and surface engineering, and it is an essential means for products to meet high quality standards. In order to make the products internationalized, there are clear requirements for the thickness of the cladding in my country's export commodities and foreign-related projects.
The measurement methods of coating thickness mainly include: wedge cutting method, optical section method, electrolysis method, thickness difference measurement method, weighing method, X-ray fluorescence method, β-ray backscattering method, capacitance method, magnetic measurement method and eddy current measurement law etc. Among these methods, the first five are destructive testing, the measurement methods are cumbersome and slow, and they are mostly suitable for the principle of sampling inspection of conventional coating thickness gauges.
X-ray and β-ray methods are non-contact and non-destructive measurements, but the devices are complicated and expensive, and the measurement range is small. Due to the radioactive source, users must comply with radiation protection regulations. X-ray method can measure extremely thin coating, double coating and alloy coating. The β-ray method is suitable for the measurement of the coating and the coating with the atomic number of the substrate greater than 3. The capacitance method is only used when measuring the thickness of the insulating coating of a thin conductor.
With the advancement of technology, especially after the introduction of microcomputer technology in recent years, the thickness gauge using magnetic method and eddy current method has taken a step forward in the direction of miniature, intelligent, multi-functional, high-precision and practical. The measurement resolution has reached 0.1 microns, and the accuracy can reach 1%, which has been greatly improved. It has wide application range, wide measuring range, easy operation and low price. It is the most widely used thickness measuring instrument in industry and scientific research.
The non-destructive method neither damages the coating nor the base material, and the detection speed is fast, so that a large amount of detection work can be carried out economically.
