Posted on 9 May, 2013 by Mathew
Details of a new process have been revealed, for alloying electrochemical production of iron, either for making iron (and oxygen!) on the moon or making electrolytic iron (and oxygen) on earth. The original process was developed for release of oxygen from moon rocks, using iridium metal electrodes. The new process uses chromium-iron electrodes.
The process has the potential to further reduce the carbon dioxide produced during steelmaking, when combined with electricity production from ‘carbon-dioxide neutral’ source.
Filed under: Academic papers, Iron, steelmaking | Tagged: electrochemistry, iron, MIT, NASA, steelmaking | 1 Comment »
Posted on 1 May, 2013 by Mathew
The dangers of using spreadsheets for calculations should never be underestimated, it’s so easy to make a copy paste error, or inadvertently corrupt your calculation. But it seems from reports that this may have been one of the more costly mistakes, and somehow not picked up by the peer review process, or public dissemination sufficient to reproduce the results. Economists from Harvard studied debt and GDP growth level and found that a 90% GDP ratio was a magic number which was bad for the economy, but recently an undergraduate repeated there calculations and found they were wrong (-0.1% GDP growth predicted should have been +2.2% growth). This results has been quoted by policy leaders to justify austerity measures around the world. The economists stand by their conclusions.
Correlation is not causation?
Link to youtube video by Liberal Viewer
Filed under: Academic papers | Leave a Comment »
Posted on 9 March, 2013 by Mathew
These are some pictures of the beautiful microstructure of super-bainite. The fine structure of bainite plates and austenite thin films is formed by isothermal transformation at 200°C (or alternatively 473.15 K, or 392 F). With this fine microstructure (or more accurately nanostructure) it is possible to reach very high strength in steel (more than 2 GPa ultimate tensile strength).
Super Bainite Before Tempering (as transformed at 200°C), as seen in transmission electron microscope
Super bainite as transformed at 200°C, as seen in scanning electron microscope.
‘Super bainite’ after severe tempering.
This is what happens if you attempt to temper at the highest possible temperature. As expected the microstructure approches equilibrium and coarsens. We found that the temperature calculated using thermodynamic software is not applicable to this heat treatment. Rather than an equilibrium structure of ferrite and carbides as we expected at this temperature, austenite, ferrite and carbide phases were all stable. On cooling, the austenite transformed, usually to pearlite as seen here, but in some cases bainite and martensite were also observed.
Read more: Severe tempering of bainite generated at low transformation temperatures (mathewpeet.org) or Severe tempering of bainite generated at low transformation temperatures (phase transformations)
Filed under: Academic papers, Steel | Tagged: equilibrium structure, isothermal transformation, scanning electron microscope, Science, tempering, transmission electron microscope | Leave a Comment »
Posted on 20 June, 2011 by Mathew
I’m very happy that my paper was accepted for publication in Metallurgical and Materials Transactions A. It took a long time from performing the experiment to presenting the results, mainly because I needed to repeat the analysis which was something I wasn’t able to make time for until I had to submit the thesis.
Surface relief caused by shear transformation of bainite
In the paper atomic force microscopy is used to measure the shear component of extremely thin plates of bainitic ferrite in superbainite. The shear component is surprisingly large compared to the value we expected of 0.23–0.28 based on previous experiments carried out after transformation at higher temperatures (such as the results by Swallow and Bhadeshia).
It seems like the higher strain may help to explain why the bainitic ferrite plates are so thin and slender. It would now be really interesting to test if that is true or not, which is something I couldn’t really do by looking at the TEM and SEM images I have already.
More details on my web-page at Mathew Peet| Papers| Surface Relief Due to Bainite Transformation at 200°C
Article is currently available electronically by using DOI
Filed under: Academic papers, Bainite, Crystallography, Papers, Steel | Tagged: Bainite, bainite transformation, Displacive transformation, Shear, Shear Component, superbainite, Surface Relief | 3 Comments »