Abstract
An oxidation study was performed on 99.99% Al, Al1%Mn and Al5%Mn materials, both in a thermogravimetric furnace, and in a muffle furnace. The mass gain behaviour for these materials was studied and compared for different temperatures and surface preparations, and was compared to previous work on Al1Mn.
Curve fitting was used with the thermogravimetric data in an attempt to develop a mathematical model to describe oxidation in the Al1%Mn materials, but a satisfactory model could not be found.
The oxidized materials were then analyzed in the Scanning Electron Microscope using EDS and Auger microprobe analysis, both for chemical composition and to analyze the structure of the oxide that was formed.
The main findings from the thermogravimetric work were are as follows:
1. Error analysis showed that the mass measurement errors were at least two orders of magnitude smaller than the mass measurements, so any differences between samples was due to different oxidation behaviour in the sample.
2. There was inconsistent oxidation behaviour for the Al1Mn surface-cleaned TGA samples; for six identical samples and experiments, five samples showed comparable eesults, while one sample showed much larger mass gain.
3. Sample preparation has a large infl
uence on oxidation behaviour in the muffle furnace.
4. Mn content has an in
uence on oxidation behavior; there was a trend of increasing
oxidation with increasing Mn content in the muffle furnace samples.
The main findings from the SEM analysis of the oxidized 99.99% Al, Al1%Mn and Al5%Mn materials are as follows:
1. The oxides formed on the Al1Mn and Al5Mn materials were thicker and different than those found on 99.99% Al
2. The oxides formed on the Al1Mn and Al5Mn materials did not contain Mn oxides
3. The oxides formed on the Al1Mn and Al5Mn materials had small particles of Mn metal completely surrounded by Al2O3
4. Mn-rich particles were found in the interior of the Al1Mn and Al5Mn samples
5. Small clusters of Mn metal were found among the Al2O3 particles on the surface of the Al1Mn and Al5Mn samples
Glow Discharge Optical Emission Spectroscopy showed that there was no measurable Mn on the surface of an as-extruded Al1Mn strip, and the Mn was deficient to a depth of some 100nm from the surface. A similar Al1Mn extruded strip that had 50µm of the surface mechanically removed also did not contain Mn on the surface, and had a similar Mn profile to the as-extruded strip.
A qualitative physical model of oxidation was suggested, based on thermogravimetric data.
Curve fitting was used with the thermogravimetric data in an attempt to develop a mathematical model to describe oxidation in the Al1%Mn materials, but a satisfactory model could not be found.
The oxidized materials were then analyzed in the Scanning Electron Microscope using EDS and Auger microprobe analysis, both for chemical composition and to analyze the structure of the oxide that was formed.
The main findings from the thermogravimetric work were are as follows:
1. Error analysis showed that the mass measurement errors were at least two orders of magnitude smaller than the mass measurements, so any differences between samples was due to different oxidation behaviour in the sample.
2. There was inconsistent oxidation behaviour for the Al1Mn surface-cleaned TGA samples; for six identical samples and experiments, five samples showed comparable eesults, while one sample showed much larger mass gain.
3. Sample preparation has a large infl
uence on oxidation behaviour in the muffle furnace.
4. Mn content has an in
uence on oxidation behavior; there was a trend of increasing
oxidation with increasing Mn content in the muffle furnace samples.
The main findings from the SEM analysis of the oxidized 99.99% Al, Al1%Mn and Al5%Mn materials are as follows:
1. The oxides formed on the Al1Mn and Al5Mn materials were thicker and different than those found on 99.99% Al
2. The oxides formed on the Al1Mn and Al5Mn materials did not contain Mn oxides
3. The oxides formed on the Al1Mn and Al5Mn materials had small particles of Mn metal completely surrounded by Al2O3
4. Mn-rich particles were found in the interior of the Al1Mn and Al5Mn samples
5. Small clusters of Mn metal were found among the Al2O3 particles on the surface of the Al1Mn and Al5Mn samples
Glow Discharge Optical Emission Spectroscopy showed that there was no measurable Mn on the surface of an as-extruded Al1Mn strip, and the Mn was deficient to a depth of some 100nm from the surface. A similar Al1Mn extruded strip that had 50µm of the surface mechanically removed also did not contain Mn on the surface, and had a similar Mn profile to the as-extruded strip.
A qualitative physical model of oxidation was suggested, based on thermogravimetric data.
