Author, Institution: Jacob Shiby Mathew, Kaunas University of Technology
Science area, field of science: Technological Sciences, Materials Engineering, T008
Scientific Supervisor: Dr. Liutauras Marcinauskas (Kaunas University of Technology, Natural Sciences, Physics, N002)
Dissertation Defence Board of Materials Engineering Science Field:
Prof. Dr. Habil. Arvaidas Galdikas (Kaunas University of Technology, Technological Sciences, Materials Engineering, T008) – chairman
Dr. Sergejs Gaidukovs (Riga Technical University, Technological Sciences, Materials Engineering, T008)
Dr. Šarūnas Meškinis (Kaunas University of Technology, Technological Sciences, Materials Engineering, T008)
Prof. Dr. Juozas Padgurskas (Vytauto Didžiojo universitetas, Technological Sciences, Mechanical Engineering, T009)
Dr. Darius Virbukas (Kaunas University of Technology, Natural Sciences, Physics, N002)
The dissertation defence takes place online.
The doctoral dissertation is at the library of Kaunas University of Technology (K. Donelaičio g. 20, Kaunas).
Degeneration of metallic surfaces such as steel from recurring usage causes surface deterioration owing to its low intrinsic hardness, thus it is imperative to coat the material surface. Plasma spraying is one of the most commonly employed processes to produce wear resistant coatings. Plasma sprayed Al2O3 (alumina) and alumina-composite coatings are customary industry materials due to its high hardness, proficient strength and toughness, and, superior tribological and insulation characteristics. Novel tribologically effective alumina-graphite and alumina-zirconia coatings were formed using the seldom employed air-hydrogen plasma spraying technique. It was demonstrated that employing a dry lubricant, such as graphite, which is passably economical in comparison to other carbon-based materials, alumina-graphite coatings with improved friction coefficients and low specific wear rates were created. The dependencies on the variations of the tribological properties of alumina-graphite and alumina-zirconia coatings on the plasma spraying parameters, the used additive types, and its concentrations were estimated. It was determined that with an optimum concentration of zirconia and with ideal plasma spraying parameters, alumina-zirconia coatings having a high wear resistance, the specific wear rates being upto 100 times lower in comparison to steel could be created.