AUTOMATIC METHOD FOR QUICKLY DETERMINING THE RESISTANCE TO CORROSION OF COATINGS APPLIED BY CHEMICAL CONVERSION.

摘要

Described is a method for determining the corrosion resistance of conversion coatings, which is regulated by the MIL-C-5541 standard, where the trained operator uses a microscope to count the cracks over a piece with dimensions of 10x3 after 168 hours of NSS tests. A quick method is proposed for determining, in an automatic and objective manner, the corrosion resistance of the chemical conversion coatings, according to the number of cracks formed during neutral salt spray tests (NSS) under the ASTM B117 standard, with the operation sequence: scanning the sample with a high-resolution digital optical scanner, for example 16,000 dpi or more, for distinguishing objects with sizes of from about 1.5 micrometres or less; treatment of the generated archive generated by an image processing software, which determines the equivalent coordinates and diameters of the zones that contain probable cracks; scan performed lengthwise a coordinate, through the diameter, applying the SVET and SRET method s, only in zones containing the probable cracks for distinguishing real cracks from stains having a similar aspect and determining the number of real cracks.