Кавітаційно-ерозійна зносостійкість зміцнених поверхонь конструкційних сталей в середовищах харчових виробництв

Abstract

Розглянуто вплив термоциклічної обробки (ТЦО), іонного азотування і полімерних покриттів на кавітаційно-ерозійну зносостійкість конструкційних сталей. Отримані результати пояснюються фізико-механічними, електрохімічними характеристиками досліджених матеріалів з покриттями.

To improve cavitation and erosion wear-resistance of metals methods of surface strengthening must be used. For this reason the paper studies the influence of thermo-cyclic treatment (TCT), ion nitriding and polymer coatings on cavitation and erosion wear-resistance of C 45, 15Cr3 and 41 Cr 4 steels. Thermo-cyclic treatment of C 45, 15Cr3 and 41 Cr 4 steels was conducted using pendulum and medium-temperature approaches. Ion nitriding of normalized and temro-cycled samples of C 45 and 41 Cr 4 steels was conducted taking advantage of hydrogen-free nitriding machine and in a nitrogen-argon mixture at 500 and 560 оС. Coatings made of polypropylene PPR2 and fluorine plastic PTFE4 were sprayed on C 45 steel by the electrostatic method and colliquated in the furnace at the temperature 200...280 оС. The thickness of polymer coating was within 200...250 mkm. Research on cavitation and erosion wear-resistance has been done taking advantage of the magnetic strictional pulsator (MSP) in neutral, acidic and alkaline environmnet (3% NaCl, serum and milk). The results of the study have shown that TCT of structural steels improves the mechanical properties of plasticity, small-and multicyclic durability, corrosion resistance and, approximately by 35%, cavitation and erosion wear-resistance under the primary influence of corrosion damage factor. The developed technology of low temperature nitriding of structural carbon steels increases their cavitation and erosion wear-resistance in 1.15, 1.63, 1.65 and 1.84 times in the 3% aqua of sodium chloride, serum, milk and lactic acid respectively, that is by 10...32% higher compared with the conventional methods of nitriding. Polymer coating based on polypropylene and PTFE allow to increase in 2 times the cavitation and erosion wear-resistance of C 45 steel in a neutral (3% NaCl) and more than in 40 times - in acidic solutions. Especially effective is the application of polymeric coverages in a sour environment, where the increase of cavitation firmness presents more than in 40 times. Thus application of fluoroplastic for making of cavitation firmness detailsincreases their wearproofness more than in 50, and from a polypropylene – 60 times.