Kozak A., Kostiuk D., Kuzavko Y.

The struggle with corrosion have became a widely recognized problem. The corrosion protection of constructions based on Al, Mg, Ti and their alloys has some specifics, caused by a corrosion type and available access to the corroding surface. Let us note that one of technological ways of preventing corrosion on Al, Ti, i.e. valve metals, are composite ceramic coatings made by the method of anode-sparkling oxidizing (MAO). Mg should be covered with thin Al or Ti coatings before MAO. Therefore the conditions of continuous and pulse signal reflection from the film coating on the massive substrate are subject of a great interest, i.e. corundum one on aluminum detail surface. The reflected acoustic signal carries the information about the coating thickness, physical and chemical qualities. Spectral analysis applied to this signal should make it possible to determine adds, brought to the signal by a concrete physical mechanism. The reflection of continuous and pulsed acoustic signals from the boundaries between various media has been theoretically and experimentally studied in sufficient detail. Corroding layer can be related to dissipative mediums (DM), in our classification the materials with strong absorption of acoustic oscillations. The general theory of reflection of an acoustic signal from the DM film covering on massive substrate is formulated in [1], and here again concretized for the corroding surfaces. The DM film covering was examined in the model of Focht, thus taking into account the inner friction and the elastic strains relaxation. The normal reflection of continuous and pulse longitudinal and transverse acoustic waves was investigated with worked-out software. Authors are grateful to BRFFI (F04R-080 grant) and ME of RB (05-505 grant).