350
H. Karakurkchi et al.
Fig. 12 Rate of voltage
change for aluminum PEO in
electrolyte 0.01 mol/dm 3
KOH at i: 5 A/dm 2 (1); 10
A/dm 2 (2); 20 A/dm 2 (3)
effect on voltage variation rate dU/dt) for the aluminum and alloys treatment when
adding MnO 4
− into the alkaline electrolyte are considerably different from that in
pure KOH solution (Fig. 13).
The voltage variation rate increases and such changes are more expressed with the
oxidizing current rising; a maximum becomes more explicit already at the voltages
of 80–95 V and as soon as a maximum is reached an abrupt drop in the voltage
variation rate is observed. So, the PEO process is stabilized.
Fig. 13 Voltage variation
rate for PEO of aluminum in
electrolyte of composition
0.01 mol/dm 3 KOH +
0.05 mol/dm 3 KMnO 4 at
current densities: 5 A/dm 2
(1); 10 A/dm 2 (2); 20 A/dm 2
(3)