Stechyshyna N. Corrosion-mechanical wear resistance of dairy equipment parts

The dissertation is devoted to the solution of the actual scientific and technical problem – increase of corrosion-mechanical wear resistance of metals in specific environments of technological processes of milk and dairy products processing by application of composite electrolytic coatings (CEC) and anhydrousnitriding in a smoldering discharge (ANSD). The analysis of working conditions of equipment parts in the dairy industry environments revealed the presence of six subspecies of corrosion-mechanical wear in the metal-medium (M + C) system: corrosion, erosion, cavitation-erosion, chemical-mechanical, gas and hydroabrasive wear and four types of environments (liquid, condensed, pasty, plastic and loose). Detected parts that wear the most intensity depending on the type of environment, type of CMZ and load value. It is shown that CEC with SiCnano and SiC5 particles with their volume content more than 8 10 % on average 6 times increase the cavitation-erosion resistance of steel 45 normalized in hard water, 11 times in 3 % NaCl solution and more than 16 times in acidic medium. Thermal and vacuum annealing of CEC increases their durability by an average of 2 times. The dependences of the change in the thickness of the nitride zone hN and the diffusion layer h on the nitriding parameters were obtained and analyzed, as well as statistical models of the relationship of nitriding parameters with the thickness of the nitride and diffusion zone and their microhardness. The X-ray structural analysis of the phase structural components of the nitrided layers was performed and the change of the crystal lattice parameters of c and a nitride particles was analyzed depending on the concentration of nitrogen in the nitride KN zone and thephase composition of the diffusion layer on 40X steel was studied depending on the nitriding modes (T, C and p). Conducted theoretical calculations show that the maximum strengthening of the nitrided layers, can be obtained by both coherent and incoherent nitrides excretion by appropriate optimization of the structure in the implementation of the calculated structural parameters – the diameter of the nitride particles and the distances between them.