How do you correctly extrapolate slopes on a Tafel (log(I) /mA vs E /V) curve? 2

[iruvinov]

Hello,

I was running a few linear polarization corrosion experiments on a titanium alloy in NaCl. Long story short, I got a funky - looking Tafel plot; the right side is almost like a corner. The program I am using (EC-Lab) extrapolates the slopes automatically but I still have to select which area it should extrapolate. Because of this corner-like anodic slope, my Ba value is very high.

Does anyone have any tips on what the correct way to extrapolate the slopes on a Tafel plot is? Sources would be greatly appreciated.

Thank you,

Igor

 

[cloa]

You need to specify how exactly you setup the linear polarisation- it might be a fault in your setup. Also at least roughly graph what you have so far.

 

[iruvinov]

It's not faulty setup because I got good results for a higher voltage sweep (0.5 mV/s) but this happened for the lower voltage sweep (0.05 mV/s).

Also, I'm not sure how to upload a picture of the graph - from what I've seen you can only URL a picture that's already up on the internet somewhere.

My main question is the extrapolation of the Tafel curve and how to properly do it.

Thanks!

 

[metengr]

Seek and ye shall find....

http://www.energy-cie.ro/archives/2010/n1-1-14.pdf

 

[SJones]

Did ASTM G102 and G59 not help?

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.

 

[iruvinov]

Thanks SJones - the ASTM papers did help with this and with some other aspects of my research as well. And the paper metengr linked me to was extremely helpful as well. Thanks again!