In our studies the effects of magnetic field was investigated.
We began our studies with conventional electropolishing (EP) to
compare the results with the ones obtained under electropolishing
using a magnetic field (MEP). Most of the results have been
performed on the austenitic AISI 316L SS, though some experiments
with the results concerning EP and MEP of ferritic AISI 430SS
have been carried out and delivered. The second material used,
the ferritic AISI 430SS was included to observe eventual effect of
ferromagnetic material against a paramagnetic one.
In Fig. 2 the effect of scan rate during conventional EP is presented.
Too small rate of scanning, referred to 0.1mVs−1, results in
quick alterations of current density together with the rise in potential
applied to the sample. On the other hand, a rapid scanning,
equalling to 10mVs−1, reveals a big jump (at a potential of 970mV
vs. MSE) up to about 13.5Adm−2 and then a drop (at the potential
of 1280mV) to about 8Adm−2, respectively. The most advantageous
scanning rate has been established at 1mVs−1, revealing
the current plateau ranging from 900 to about 1400mV vs. MSE
(mercury-sulphate electrode).
Further polarization characteristics have been obtained under
one selected scan rate equalled 1mVs−1, and electrolyte temperature
of 60±1 ◦C. Fig. 3 presents polarization curves obtained on
AISI 316L SS under three treatment conditions: EP—conventional
electropolishing under a natural convection (without mixing, v =0ms−1), the EP (v > 0) referred to a forced convection (moderate
mixing at the relative electrolyte velocity of about 0.1ms−1),
and EP (v 0) referred to a forced convection with an intensive
mixing at the relative electrolyte velocity of over 0.2ms−1.
In each case the cd plateau has been observed, with the lowest
current density of about 7Adm−2 obtained at conventional
EP carried out under natural convection (in still electrolyte), and
at much higher cd of about 34Adm−2 at EP with forced convection
(mixing, practically independent on its intensity). The other
difference was the plateau potential range, from about 900 to
1450mV vs. MSE obtained under natural convection, and much
shorter, from about 1150mV to about 1500mV vs. MSE in case
of forced convection (electrolyte stirring, also independent on its
intensity).
In Fig. 4 the EP polarization characteristics obtained on AISI 316L
SS samples under three different electrolyte temperatures, referred
both to the natural convection (still electrolyte), and a forced con-