Interactions between Carbon‐Bonded Alumina Filters and Molten Steel: Impact of a Titania‐Doped Filter Coating

Abstract

Herein, the influence of adding titania to the carbonaceous alumina coating of Al2O3–C filters on the interactions with molten steel is investigated. Therefore, coated filters are immersed for 30 s in molten steel (42CrMo4) at 1580 °C. Mainly by microstructural and chemical analyses, the immersed filters as well as the solidified steel are characterized. Due to the reducing atmosphere of the heat treatment during sample manufacturing, the formation of aluminum titanate phases in the coating is not observed. During immersion, on the one hand, titania acts as the sintering agent for alumina within the coating and for precipitated alumina inclusions from the melt. On the other hand, dissolved titanium in the melt decreases the surface tension and thus increases wetting of the steel melt on the filter surface. The results indicate that more but smaller alumina inclusions remain in the solidified steel if titania is added to the coating. Thus, the modification of alumina inclusions by adding titania to the filter coating presents a way to tailor these inclusions depending on the product's application.

Investigations on Oxide Particles Formed during Sintering of CrMnNi‐Transformation‐Induced Plasticity (TRIP) Steel Powder Metallurgically Materials Using Automatic Feature Analysis

“…Particles classified as Al 2 O 3 or SiO 2 are likely to occur in cast steel. [22,23] Imperfections include all other particles, which were caused from voids or particles excluded from other classes due to their divergent chemical composition.…”

“…However, the accuracy and reproducibility of AFA investigations were previously proved with samples of high-alloyed cast steel. [22,23]…”

“…The number of particles per area is one to two orders of magnitude higher than measured for cast steel samples. [22,23] Thus, the microstructure formation and the resulting mechanical properties of CrMnNi steels are vulnerable to oxide-particle formation during PM manufacturing.…”

Interaction of Fe‐Containing, Secondary Al–Si Alloy with Oxide and Carbon‐Containing Ceramics for Fe Removal

“…During the past years, new filtering techniques and new active filter materials have been developed to expand the range of application and to improve filter efficiency. [ 30,33–37 ] These techniques include utilization of mechanisms like active deposition of impurity inclusions on the filter [ 33–36 ] and reactive interactions, e.g., by formation of inclusion bridges [ 30 ] or direct heterogeneous precipitation of inclusions on the filter. [ 34 ] This is achieved by selection of suitable chemistry of the filter or a coating [ 35,37 ] and surface conditions including roughness [ 30,35,37 ] and using combined filter systems or composite filters.…”