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Title: Wetting and Reaction Characteristics of Al2O3/SiC Composite Refractories By Molten Aluminum and Aluminum Alloy

Abstract

The reactive wetting behavior in molten aluminum (Al) and Al alloy was investigated for alumina-silicon carbide composite refractory materials using an optimized sessile drop method at 900oC in a purified Ar-4% H2 atmosphere. The time dependent behavior of the contact angle and drop geometry was monitored and the wetting kinetics were determined. The initial contact angle between the liquid Al/Al alloy and the refractory substrates was found to be greater than 90 and to gradually decrease with time. For two of the materials, it was found that the contact angles decreased to and angle less than 90 by the end of the two-hour test. For the third material, the contact angle was still greater than 90 at the conclusion of the two-hour test. The difference in wetting properties among the three types of refractories is attributed to their microstructural and compositional variations. The effect of magnesium in the molten Al alloy drops on the wetting kinetics and the reaction with the refractory substrates are also discussed. The results obtained provide important understanding of the wetting and corrosion mechanisms of alumina and silicon carbide materials in contact with molten aluminum.

Authors:
 [1];  [1];  [1];  [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
931047
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: 31st International Cocoa Beach Conference on Advanced Ceramics & Composites, Daytona Beach, FL, USA, 20070121, 20070121
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALLOYS; ALUMINIUM; CARBIDES; CERAMICS; CORROSION; GEOMETRY; KINETICS; MAGNESIUM; REFRACTORIES; SILICON CARBIDES; SUBSTRATES; COMPOSITE MATERIALS

Citation Formats

Hemrick, James Gordon, Xu, Jing, Peters, Klaus-Markus, Liu, Xingbo, and Barbero, Ever J. Wetting and Reaction Characteristics of Al2O3/SiC Composite Refractories By Molten Aluminum and Aluminum Alloy. United States: N. p., 2007. Web.
Hemrick, James Gordon, Xu, Jing, Peters, Klaus-Markus, Liu, Xingbo, & Barbero, Ever J. Wetting and Reaction Characteristics of Al2O3/SiC Composite Refractories By Molten Aluminum and Aluminum Alloy. United States.
Hemrick, James Gordon, Xu, Jing, Peters, Klaus-Markus, Liu, Xingbo, and Barbero, Ever J. Mon . "Wetting and Reaction Characteristics of Al2O3/SiC Composite Refractories By Molten Aluminum and Aluminum Alloy". United States. doi:.
@article{osti_931047,
title = {Wetting and Reaction Characteristics of Al2O3/SiC Composite Refractories By Molten Aluminum and Aluminum Alloy},
author = {Hemrick, James Gordon and Xu, Jing and Peters, Klaus-Markus and Liu, Xingbo and Barbero, Ever J},
abstractNote = {The reactive wetting behavior in molten aluminum (Al) and Al alloy was investigated for alumina-silicon carbide composite refractory materials using an optimized sessile drop method at 900oC in a purified Ar-4% H2 atmosphere. The time dependent behavior of the contact angle and drop geometry was monitored and the wetting kinetics were determined. The initial contact angle between the liquid Al/Al alloy and the refractory substrates was found to be greater than 90 and to gradually decrease with time. For two of the materials, it was found that the contact angles decreased to and angle less than 90 by the end of the two-hour test. For the third material, the contact angle was still greater than 90 at the conclusion of the two-hour test. The difference in wetting properties among the three types of refractories is attributed to their microstructural and compositional variations. The effect of magnesium in the molten Al alloy drops on the wetting kinetics and the reaction with the refractory substrates are also discussed. The results obtained provide important understanding of the wetting and corrosion mechanisms of alumina and silicon carbide materials in contact with molten aluminum.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}

Conference:
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  • The reactive wetting behavior of three types of alumina-silicon carbide composite refractory materials was investigated in contact with molten aluminum (Al) and Al alloy using an optimized sessile drop method at 900oC in a purified Ar-4% H2 atmosphere. The time dependent behavior of contact angle and droplet geometry was monitored and the wetting kinetics was identified. The initial contact angle between the liquid Al/Al alloy and two of the refractory substrates was found to be an obtuse angle, which gradually changed to a 90o angle and then eventually to an acute angle with time. However, the wetting angle for themore » third refractory substrate was found to stay at an obtuse angle for the entire two-hour duration of the experiment. The difference in wetting properties among three types of refractories is attributed to be due to their microstructural and compositional variations. The significant effect of the alloying magnesium added to the molten Al alloy droplets in regard to the wetting kinetics and the influence on the reaction with the refractory substrates is discussed. The results obtained provide important understanding on the wetting and corrosion mechanisms of alumina and silicon carbide materials in contact with molten aluminum.« less
  • The effect of the interfacial thickness of the reaction layer on the interfacial shear properties and the tensile strength of double carbon-coated SCS-6 SiC fiber in Ti-15Mo-5Zr-3Al alloy matrix composite was examined. The major reaction layer thickness, that is, titanium-carbide (TiC) layer thickness, varied with heat-exposure temperature and time, respectively, and the resultant mean thickness of the reaction layer of the composite ranged from 0.4 to 1.7 {micro}m. The critical interfacial toughness, G{sub i}{sup c}, and the mean shear sliding resistance, {tau}{sub s}, were evaluated by the thin specimen pushout technique. Tensile strength of the silicon-carbide (SiC) fiber extracted frommore » the titanium alloy matrix before and after the heat exposure was determined in relationship to the thickness of the reaction layer. The critical interface toughness, G{sub i}{sup c}, for the failure of the root of the reaction layer was {approx}4 J/m{sup 2}, and the average shear sliding resistance of the interface, {tau}{sub s}, was 102 to 118 MPa. The interfacial shear mechanical properties were adequate to prevent failure of the fiber due to the stress concentration caused by cracks that formed first in the reaction layer. The results showed that when the growth of reaction layer was within 1.7 {micro}m, the mean strength of the extracted fiber was unaffected by the existence of the reaction layer because of weak bonding between it and the fiber. However, with the increase of the reaction layer thickness, the strength distribution of the extracted fiber tended to Weibull bimodal distribution.« less
  • The slow crack growth properties of an Al2O3/SiC whisker composite have been evaluated using indented specimens in a dynamic fatigue experiment. The composite has a significantly higher resistance to slow crack growth compared to a fine grained Al2O3 material as indicated by the relative values of the slow crack growth parameter, n. The slow crack growth regions were intergranular in both cases implying that the matrix-whisker interface plays an important role in determining the slow crack growth properties of the composite. 35 refs.
  • Rare-earth doping of aluminosilicate refractory compositions has been shown to impart improved resistance to attack by molten aluminum alloys. The basis for this improved alloy attack resistance was investigated. The addition of rare-earth oxide to bauxite was found to alter the microstructure to form large, uniformly shaped corundum crystals interlinked with cerium-containing strands. It was concluded that this unique microstructure was responsible for the enhanced attack resistance of the refractories. Other possible causes for improved alloy attack resistance, such as enhanced sintering, excess oxygen provided by the CeO[sub 2] dopant, or higher thermodynamic stability of the phases formed in themore » doped refractory compositions, were not consistent with the experimental findings.« less
  • An improved sessile drop technique which prevented the oxidation of aluminum was used to measure the changes in contact angle between boron nitride and molten aluminum in a purified He-3% H[sub 2] between 1,173 and 1,373 K. The contact angle progressed through the four wetting phases similar to other ceramics when the results were plotted on a logarithmic time scale. However, at and above 1,273 K the equilibrium contact angle was 0[degree] which is much less than those of typical ceramics. Using the value in phase II, the original contact angle between boron nitride and aluminum (contact angle between non-reactedmore » boron nitride and aluminum) was estimated to be 133[degree] at 1,373 K. The wetting progressed by producing another non-wetting material, AlN, in this non-wetting system. The detailed mechanism of the solid/liquid/vapor interfacial advance during wetting in such a system was also explained using Cassie's equation.« less