A Mathematical Model for the Growth of Aluminum Etch Tunnels
Date
Authors
Major Professor
Advisor
Committee Member
Journal Title
Journal ISSN
Volume Title
Publisher
Authors
Research Projects
Organizational Units
The function of the Department of Chemical and Biological Engineering has been to prepare students for the study and application of chemistry in industry. This focus has included preparation for employment in various industries as well as the development, design, and operation of equipment and processes within industry.Through the CBE Department, Iowa State University is nationally recognized for its initiatives in bioinformatics, biomaterials, bioproducts, metabolic/tissue engineering, multiphase computational fluid dynamics, advanced polymeric materials and nanostructured materials.
History
The Department of Chemical Engineering was founded in 1913 under the Department of Physics and Illuminating Engineering. From 1915 to 1931 it was jointly administered by the Divisions of Industrial Science and Engineering, and from 1931 onward it has been under the Division/College of Engineering. In 1928 it merged with Mining Engineering, and from 1973–1979 it merged with Nuclear Engineering. It became Chemical and Biological Engineering in 2005.
Dates of Existence
1913 - present
Historical Names
- Department of Chemical Engineering (1913–1928)
- Department of Chemical and Mining Engineering (1928–1957)
- Department of Chemical Engineering (1957–1973, 1979–2005)
- Department of Chemical and Biological Engineering (2005–present)
- College of Engineering(parent college)
Related Units
Journal Issue
Is Version Of
Versions
Series
Department
Abstract
A simulation of the growth of pits on aluminum during anodic etching in hot chloride solutions was developed. The simulation is based on equations for mass transport and for the potential-controlled removal of chloride ions from the dissolving surface. The latter process initiates oxide passivation. Etch pits are found to transform into tunnels which at first maintain parallel sidewalls and then begin to taper. The predicted tunnel shapes agree quantitatively with those measured experimentally. Tunnel formation is possible only when the potential at the tunnel entrance during etching is within 20-30 mV of the repassivation potential; as a result, the size of the dissolving surface is nearly constant during pit growth. In the tapered-width regime of tunnel growth, the AlCl3 concentration at the end of the tunnel is near saturation, despite the absence of precipitation from the model equations. The model shows that this condition derives from the low conductivity of the concentrated solution, coupled with the sensitivity of the rate of surface chloride removal to changes in the potential at the dissolving surface.
Comments
This article is from Journal of the Electrochemical Society 148 (2001): B236–B242, doi:10.1149/1.1369368. Posted with permission.