A study of double oxide film defect behaviour in a quiescent aluminium melt

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Authors

External organisations

  • University of Cambridge
  • Department of Materials Engineering
  • Shahid Bahonar University of Kerman

Abstract

The change in the volume of an air bubble held within commercially pure liquid aluminium was recorded by real time x-ray radiography, to estimate the behaviour of double oxide film defects after entrainment in liquid aluminium. This showed that first oxygen and then nitrogen were consumed by the melt to produce Al 20 3 and AIN respectively. Varying the initial hydrogen contents of the melt also showed that hydrogen could diffuse into the atmosphere within a trapped bubble, and cause it to expand. A mathematical model was developed using the consumption rates obtained from this experiment that included the diffusion of hydrogen, which suggested that the atmosphere within a double oxide film defect should be consumed by the surrounding AI melt in less than two minutes. In addition, a double oxide film-free liquid aluminium melt was poured into ceramic test bar moulds which then held in the liquid state for 20 minutes. Study of the fracture surfaces suggested that the two non-wetting surfaces of a double oxide film defect might bond to each other, after the internal atmosphere of the film was consumed, and that this could occur in 20 minutes or less.

Details

Original languageEnglish
Title of host publicationInstitute of Cast Metals Engineers - 67th World Foundry Congress, wfc06: Casting the Future
Publication statusPublished - 2006
Event67th World Foundry Congress: Casting the Future, wfc06 - Harrogate, United Kingdom
Duration: 5 Jun 20067 Jun 2006

Conference

Conference67th World Foundry Congress: Casting the Future, wfc06
CountryUnited Kingdom
CityHarrogate
Period5/06/067/06/06

Keywords

  • Aluminium alloys, Hydrogen porosity, Oxide films