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5242 |
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Comparison of solution precursor plasma spraying and high velocity solution precursor flame spraying in coating functional titania and alumina films |
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Phuong Vu / University of Stuttgart, Germany Andrea Förg / Institut für Fertigungstechnologie keramischer Bauteile, Universität Stuttgart, Germany Andreas Killinger/ Institut für Fertigungstechnologie keramischer Bauteile, Universität Stuttgart, Germany |
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Actively photo-catalytic TiO2 and thermally stable ± Al2O3 phase are two materials that are well introduced and still of high interest for numerous environmental and electronic applications in industry. Both materials are most suitable to be sprayed by using liquid feedstock, as the market offers a wide range of fine and ultra fine powders, ready to use suspensions as well as all kind of precursors. Both oxides and most related precursors are quite inexpensive and rather uncritical in handling. In recent studies, the solution precursor plasma spraying (SPPS) was shown as a promising method for coating of those functional titania and alumina films. Besides SPPS, high velocity solution precursor flame spraying (HVSPFS) is offering a new possibility to deposit those coatings. However, only little information about the effects of SPPS and HVSPFS process parameters on the resulting coatings is available. In this study, several solutions were prepared from different precursors successively sprayed by both SPPS and HVSPFS. XRD, SEM, optical microscopy and interferometry were used to characterize the properties of the coatings. Results of the characterizations helped to evaluate effects of solution composition on the formation of the ceramic functional films. In a further step, the modification of precursor solutions by controlled adding of organic compounds is investigated. The addition can improve process efficiency, since they work as an additional heat source during their combustion. Furthermore, during decomposition in flame or plasma, the organic compounds can work as a carbon donator source, behaving as a reduction agent hence influencing the flame respectively plasma chemistry. Keywords: titania, alumina, functional ceramic coatings, SPPS, HVSPFS. |