Interaction of Aluminum with Silica Based Ceramics
Interactions between A356 aluminum (Al-Si alloy) and dense fused silica (FS) riser tubes used for low-pressure casting of aluminum alloys were evaluated using a sessile drop approach. The tubes have a short service life, but cost and thermal shock resistance make them an effective solution. The main problem encountered during use is the reaction of aluminum with silica to form alumina and silicon, which causes failure. Tests have been conducted on as-fired (uncoated) and modified (coated) tubes. Experiments were carried out in a horizontal furnace at 1225ºC under argon to minimize the effect of the aluminum oxide on the interactions at the alloy-silica interface. Images of the drop were acquired and contact angle values were estimated for uncoated and coated samples, but no significant differences in the contact angles were observed. Scanning electron microscopy revealed the presence of cracks at the interface between the reaction zone and the unreacted silica. The presence of reaction products (silicon in the reacting alloy and aluminum in a reaction zone between the alloy and the unaffected silica) has been confirmed using energy dispersive spectroscopy. A two layer coating system was found to be effective in reducing penetration of the aluminum alloy.
J. M. Soto et al., "Interaction of Aluminum with Silica Based Ceramics," Advances in Refractories of the Metallurgical Industries IV, Canadian Institute of Mining, Metallurgy, and Petroleum, Aug 2004.
Materials Science and Engineering
United States. Department of Energy
Keywords and Phrases
Aluminum Base Alloys; Aluminum Production; Casting; Ceramic Materials; Contact Angle; Downstream Processes; Silicon Dioxide
Article - Conference proceedings
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