In general, metal targets show high reflectivity and silvery white in the range of visible light (380-780nm), but some non-ferrous metals, such as gold and copper, have selective absorption in a specific wavelength range, so special colors appear. In the light near 470nm, the selective absorption of gold is due to the electron transition, so it shows a unique golden yellow color. In the actual coating, I often use the method of target plus gas to form metal compounds to debug various colors. The reflectance curves of various metal compounds to the spectrum are different, such as the reflectance curves of gold, silver, aluminum, iron and tin in the figure below. It can be seen from the figure that the reflectance curves of tin and gold are relatively similar, so their colors are similar. Black series, such as tic and CRC, are black because of their low reflectivity and absorption of most wavelengths of visible light.
In addition, another characteristic of light, interference, is often used in decorative films, such as blue and purple. When the amount of oxygen reaches a certain level, the color of the film changes with the thickness of the filmChina Multi-arc ion coating machine Manufacturers
Of course, there are other films that can achieve this interference effect, such as silicon nitride and silicon oxide
In theory, I can plate many colors through the interference effect of the film.
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