Corrosion Potential: nitonol to stainless steel
I am looking for the galvanic potential between nitinol (nickel-titanium) and stainless steel (316L). Does anyone have an idea what that potential is? Where to look for it?
Thanks in advance.Gil Naor
Rafael Medical Technologies - Caesarea
Try the Metals Handbook by the American Society for Metals.
I have an old edition which does not cover Nitinol. You need to study the potential in the environment of interest, since the potentials can flip-flop in various corrosive environments.
The static corrosion potentials are measured in a 3.5% NaCl solution representing a standard corroding atmosphere with respect to a calomel electrode. In the ESA Journal 1989, vol 13 p199," Bimetallic Compatible couples", you will find the EMF of more than 160 metals and alloys measured in 3.5% NaCl.
Nitrinol (45Ti,55Ni): EMF= -0.33 V
AISI 316 (18Cr,13Ni,2Mo,rem Fe, passive): EMF= -0.07 V
The position in the galvanic series gives some indication about the magnitude of the coupling effect between two metals. The potential can vary with time in a particular environment. The relative position in the galvanic series may change, depending on the time of immersion. The galvanic series are quite useful as an indication as an indication of the general trend in galvanic corrosion, but it does not give the actual extend of galvanic corrosion.
A good guide for controlling this type of corrosion is PD 6484:1979, the "Commentary on corrosion at bimetallic contacts and its alleviation" from BSI (Britisch Standard Institution).Dr. Ton de Rooij
European Space Agency - Noordwijk, The Netherlands
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