Student M.M., Hvozdetskyi V.M., Dzhoba Y.V. Effect of high pressure air jet on the properties of electric arc coatings.
Keywords:
powder wire, lamella coatings, oxide films, abrasive wear resistance.Abstract
Electro-arc metallization is technologically the easiest and cheapest method among gas-thermal spraying methods. Powder wires specially developed for spraying have substantially expanded the scope of application of the method of electro-arc metallization. New restorative and protective coatings with high performance characteristics of various functional purpose are sprayed from the developed powder wires. The influence of the air jet pressure on the melting conditions and the structure of the coatings deposited by the method of electric arc spraying was determined. The impact of the cutting pressure on the angle of atomization is determined. The higher droplet temperature during the formation of the coatings is achieved by reducing the angle of sputtering.
The air flow velocity increases 2 times from 300 to 600 m / s when the air jet pressure increases from 0.6 to 1.2 MPa. increase. Therefore, the rate of dispersed dropletsincreases from 60 - 90 m / s to 160 - 220 m / s, and the size decreases when spraying electrode wires with an air jet. Dispersed droplets of a smaller size are more easily captured by a high-speed air jet. They hit the surface more deformed when struck. This reduces the porosity of the coatings and increases the number of pieces of microwaving lamellae.
In the process of crystallization and cooling of droplets in the cold part, their dimensions are reduced. Reducing the size of droplets contributes to the formation of residual strain tension. The tensile stress in the coating for the value of 0.7 cohesive strength leads to the formation of microcracks.
References
2. Pokhmurskyi V. I. Arc-sprayed iron-based coatings for erosion-corrosion protection of boiler tubes at elevated temperatures. Pokhmurskyi V. I., Student M.M., Pokhmurska H.V., Student O.Z, Hvozdecky V.M., Stupnytskyi T.R. Journal of Thermal Spray Technology, 2013, vol:22.
3. Effect of high-temperature corrosion on the gas-abrasive resistance of electric-arc coatings. M.M. Student, H. V. Pokhmurs’ka, V.M. Hvozdets’kyi, M.Ya. Holovchuk, M.S. Romaniv. Materials Science. 2009. 45, N 4. P. 481-489.
4. High-temperature corrosion of electric-arc coatings sprayed from powder core wires based on the Fe–Cr–B–Al system. M. Student, Yu. Dzioba, V. Hvozdets’kyi, H. Pokhmurska, B. Wielage, T. Grund. Materials Science. 2008. 44, 5. P. 693-699.
5. Optimization of the Chromium Content of Powder Wires of the Fe–Cr–C and Fe–Cr–B Systems According to the Corrosion Resistance of Electric-Arc Coatings. Stupnyts’kyi, T.R., Student, M.M.,Pokhmurs’ka, H.V., Hvozdets’kyi, V.M Materials Science. September 2016, Volume 52, pp 165–172.
6. The influence of size and speed of drops on the structure and properties of electric-ARC sprayed coatings. Pokhmurs'ka, H., Student, M., Hvozdetskyi, V., Stupnytskyi, T., Posuvailo, V. Proceedings of the International Thermal Spray Conference 2017.
7. Bartenev S.S., Fedko Yu.P., Grigorov A.I. Detonatsionnyie pokryitiya v mashinnostroenii. L. Mashinostroenie, Leningrad otd.-nie. 1952. 215 s., il.
8. MetodichnI vkazIvki do IndivIdualnih zanyat ta vikonannya IndivIdualnoYi roboti «Rozrahunok sopla Lavalya» z kursIv «SpetsrozdIli teplofIziki» ta "RozshiryuvalnI I kompresornI turbomashini dlya gazovoYi ta naftovoYi promislovostI". Ukladach S. M. VanEEv. Sumi. Vid-vo SumDU. 2009. 22s.
9. Babichev M. A. Metodyi opredeleniya vnutrennih napryazheniy v detalyah mashin. M. Izd-vo AN SCCR, 1955. 132 s.
