A novel process for the liquid feedstock plasma spray of ceramic coatings with nanostructural features [Elektronische Ressource] / von Roberto Siegert

A Novel Process for the Liquid Feedstock Plasma Spray of Ceramic Coatings with Nanostructural Features Dissertation Zur Erlangung des Grades Doktor-Ingenieur Der Fakultät für Maschinenbau Der Ruhr-Universität Bochum Von Roberto Siegert Aus Deutschland Bochum, 2005 Tag der mündlichen Prüfung: 13. Oktober 2005 Erster Referent: Prof. Dr. D. Stöver Zweiter Referent: Prof. Dr. K. Landes Abstract I 1. Abstract This study is focused in the process optimization and implementation of the liquid feedstock plasma spray process conducted at atmospheric pressure, in which the feedstock is injected into a free expanding plasma jet generated by industrial-type DC torches, in the form of a suspension or solution-precursor. In here, a liquid carrier is used to transport feedstock particles with sizes falling into the submicrometric and nanometric range, into the useful region of the plasma jets. This condition brings about a series of important changes in the microstructure of the deposited coatings, highlighted by a reduction in coating-building splats of up to 3 orders magnitude as compare to those observed in standard plasma spray process, and by a fine porosity with pore sizes in the nanometer range. A universal apparatus for the precise dosage of the liquid feedstock was developed considering the geometrical constraints of the different torches under consideration.