Corrosion Resistance of Steel of the Frames of Boom Sprayers
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CORROSION RESISTANCE OF STEEL OF THE FRAMES OF BOOM SPRAYERS R. L. Leshchak,1 А. V. Babii,2 R. А. Barna,1 and А. М. Syrotyuk1,3
UDC 620.193.28
We perform the comparative analysis of the corrosion resistance of St3ps steel in demineralized water and in saturated solutions of the Nurelle-D insecticide and UN-32 complex liquid fertilizer. It is shown that, in demineralized water, the general corrosion of the steel surface is predominant. In a solution of insecticide, parallel with general corrosion, we observe a partial realization of pitting corrosion. In a medium of mineral liquid fertilizer, we observe the passivation of the metal surface caused by phosphorus-containing corrosion inhibitors, which leads to the inhibition of the general corrosion. However, local violations of the passive state of the metal surface lead to the intense formation of corrosion pits, which is dangerous due to the possibility of their development accompanied by the initiation of cracklike defects in the structures. Keywords: boom sprayers, low-carbon structural steel, corrosive media, complex liquid fertilizers, liquid insecticides, corrosion rate, corrosion current density, corrosion potential, corrosion resistance.
Introduction To increase the corrosion resistance of components of the agricultural machines, it is customary to add corrosion inhibitors or substances aimed at reducing corrosive activity to the compositions of liquid mineral fertilizers and plant-protection agents. Despite these measures, the level of damage caused by corrosion is significant [1, 2]. In this case, the role of determining factor is played by the physicochemical interactions, which lead to the formation of various corrosive substances, namely, ammonia, hydrogen sulfide, or substances containing chlorine, potassium, ammonia, and other ions. Thus [1], ammonia nitrates ( NH 4 NO 3 ) or ammonia dihydrophosphate ( (NH 4 )(H 2 PO 4 ) ) cause metal corrosion as a result of the hydrolysis of acids formed in the case where the pH value of the medium decreases. The corrosion rate depends on numerous factors and, in particular the corrosiveness of the medium, the time of its action, the chemical compositions of metallic alloys, mechanical stresses, and specific features of the machines and mechanisms (contact of different materials, welded, bolted, and riveted joints, etc.). Moreover, corrosion defects may turn into efficient stress concentrators [3, 4], especially under the combined action of corrosive working media and static or dynamic loads [5]. As a final result, this may lead to the fracture of a structural element or to the failure of the entire mechanism. The aim of the present work is to perform comparative analysis of the corrosion resistance of St3ps steel in demineralized water and in saturated solutions of an insecticide and of a complex liquid fertilizer. 1 2 3
Karpenko Physicomechanical Institute, Ukrainian National Academy of Sciences, Lviv, Ukraine. Pulyui Ternopil National Technical University, Ternopil, Ukraine. Corresponding author; e-mail: syrotyu
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