Online detection method of chrome-free coating film thickness on strip steel surface

摘要

This invention relates generally to measurement of coating film thickness on surface of strip steel, and particularly, to a measuring method of chromium-free coating film thickness on surface of strip steel which comprises the following steps: selecting two water-soluble chemical substances containing elements P, Ca, Ti, Ba or Sr and not reacting with a chromium-free coating liquid; adding the two water-soluble chemical substances selected in 1) into the chromium-free coating liquid and agitating the them to be homogeneous, thereafter, fabricating a reference sample of coating film; using a ray emitted by an off-line film thickness instrument to excite the two water-soluble chemical substances so as to obtain characteristic spectrums to obtain a correction function expression between the measured film thickness and the thickness correction value by fitting; adding the water-soluble chemical substance which has a weak characteristic spectrum into a chromium-free coating liquid, and using the correction function expression to obtain the actual coating film thickness. By means of on-line detection, the invention is capable to monitor film thickness effectively and optimize the coating process continuously; with high precision, and with no adverse effect on adhesiveness, corrosion-proof and environmental performance of the coating film.