| Résumé : |
There are many reasons why a paint or coating can fail prematurely, even something quite simple such as painting over dirt, or something quite complicated such as poor chemical resistance or paint not being applied at the proper mix ratio. Many laboratory techniques can aid in determining the cause of a coating failure, such as optical microscopy, infrared spectroscopy, scanning electron microscopy energy dispersive X-ray spectroscopy {SEM-EDS), gas chromatography-mass spectroscopy (GCMS) and differential scanning calorimetry (DSC). Regardless of which laboratory techniques might be used, it is important to determine whether or not there is a pattern to the failure. Recognition of a pattern can aid in finding the cause of a failure and also sometimes lower the cost of the analysis by helping the investigator choose the most appropriate laboratory tests.
Pattern recognition is in itself a science. indeed, there are scientific journals and technical societies devoted exclusively to this concept. Encyclopedia Britannica defines pattern recognition in computer science as "the imposition of identify on input data, such as speech, images, or a stream of text, by the recognition of and delineation of patterns it contains and their relationships."
Google uses pattern recognition algorithms to identify the faces of human beings in digital images captured by their street view cameras so that the faces of these people can be blurred to protect their privacy. But in the context of this article, pattern recognition means identifying and correlating events with locations, and subsequently correlating chemical or physical properties with those locations. This depends more on curiosity and making good observations (or asking the right questions if the investigator has not been onsite) than on algorithms.
Not all coating failures have patterns {and this in itself is an important observation). For instance, if a painted structure is essentially failing everywhere, this suggests that either the paint itself is defective, or that the wrong generic type of paint was specified. However, in those cases where there is a clear pattern to the failure, being aware of this pattern can often assist in determining its cause. In this article, several coating failures will be discussed where pattern recognition played an important role in their solution. |
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The importance of pattern recognition in failure analysis in JOURNAL OF PROTECTIVE COATINGS & LININGS (JPCL), Vol. 32, N° 12 (12/2015)
