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Formation of Corundum, Magnesium Titanate, and Titanium(III) Oxide at the Interface between Rutile and Molten Al or AlSi7Mg0.6 Alloy
Author(s) -
Salomon Anton,
Voigt Claudia,
Fabrichnaya Olga,
Aneziris Christos G.,
Rafaja David
Publication year - 2017
Publication title -
advanced engineering materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 114
eISSN - 1527-2648
pISSN - 1438-1656
DOI - 10.1002/adem.201700106
Subject(s) - materials science , corundum , rutile , alloy , oxide , aluminium , titanium , metallurgy , titanate , niobium , spark plasma sintering , ceramic , titanium aluminide , chemical engineering , intermetallic , engineering
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‐Al 2 O 3 ) filters coated with rutile (TiO 2 ) 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 Al 2 O 3 at the surface of the functionalized filter. Al 3 Ti and Ti 2 O 3 are found as minor phases for long operation times. In the case of aluminum alloy AlSi7Mg0.6, the surface of the TiO 2 coatings is covered by MgTiO 3 . Additional phases are Al 2 O 3 and Al 3 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.