Corrosion of copper, 68 brass, aluminum alloy D16 and steel St3 has been analyzed in natural fresh waters. The date obtained are indicative that the corrosion rates of copper and alloys of nonferrous metals in natural river waters at the initial stage of corrosion process are essentially reduced while subsequently their corrosion rates tend to increase which the authors associate with the destruction of protective film on their surface. Steel in 5 river waters examined also corrodes with high rates; however, in 72 hours its rates get stabilized and tend no toward rise.

By the method of polarization measurements there have been investigated the corrosionelectrochemical properties of steel 09G2S which was obtained by means of the powder metallurgy. Similar measurements were carried out for compact steel in order to compare the obtained data. Anodic and cathodic curves taken in the sea water showed that corrosion-electrochemical properties of both steels were identical, i.e. both cathodic and anodic processes on these steel samples proceed according to the same mechanism with the only difference that currents observed on the powder electrode are almost 2.5 times up from those on the compact electrode. It revealed that the corrosion rate of powder steel is also up 2.5 times from that on the compact steel. Corrosion-electrochemical studies into sulfate solutions with different pH values showed that as pH increases, the stationary potentials of steels shifts to the negative side while rates of cathodic and anodic processes decrease. To our thinking, the transition regions on anodic curves result from the competing adsorption between OHand ions. The higher dissolution rates of the powder electrode in the investigated solutions are, on the one hand, due to high true surface of the powder steel and to non-equipotentiality of surface specified steel, on the other hand.

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