Formation of Corundum, Magnesium Titanate, and Titanium(III) Oxide at the Interface between Rutile and Molten Al or AlSi7Mg0.6 Alloy1 . Issue 9 (22nd May 2017)

• Record Type: Journal Article
• Authors: Salomon, Anton; Voigt, Claudia; Fabrichnaya, Olga; Aneziris, Christos G.; Rafaja, David
• Other Names: Aneziris Christos guestEditor.; Fey Tobias guestEditor.
• Is Part Of: Advanced engineering materials. Volume 19:Issue 9(2017)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-05-22
• Subjects: Materials -- Periodicals; 620.11
• DOI: 10.1002/adem.201700106
• Languages: English
• ISSNs: 1438-1656

Abstract

Abstract : For the filtration of oxide inclusions in aluminum melts, active materials covering the surface of ceramic filters are developed permanently. In this study, corundum (α‐Al2 O3 ) filters coated with rutile (TiO2 ) coatings are exposed to molten aluminum and to aluminum alloy AlSi7Mg0.6, respectively. For pure aluminum, the chemical reactions occurring at the interface between the metal melt and the filter surface are found to lead primarily to the formation of Al2 O3 at the surface of the functionalized filter. Al3 Ti and Ti2 O3 are found as minor phases for long operation times. In the case of aluminum alloy AlSi7Mg0.6, the surface of the TiO2 coatings is covered by MgTiO3 . Additional phases are Al2 O3 and Al3 Ti. One part of the interface reaction experiments is performed on powder mixtures to identify the reaction products, another one on functionalized filters to estimate the reaction kinetics. The experiments are performed in a Spark Plasma Sintering apparatus, which offers high heating rates that are comparable with those in standard cast processes, but impedes the macroscopic flow of the melt in case of the bulk samples. The equilibrium state is concluded from thermodynamic calculations using the CalPhaD method. Abstract : Interfacial reactions between rutile and molten pure Al or molten AlSi7Mg0.6 alloy are studied. Microstructural analyses are verified by thermodynamic calculations. TiO2 is reduced leading to the formation of corundum with small amounts of intermediate Ti2 O3 (pure Al) or intermediate MgTiO3 preceding corundum (AlSi7Mg0.6). Depending on the contact area, the respective oxide formation inhibits the formation of Al3 Ti or (Al, Si)3 Ti.