[institut] [phys4phys] Seminar Fizickog fakulteta

[Mirzeta Savic]

Seminar Fizičkog fakulteta
Sreda, 28. februar 2024. godine, 12.15 časova u sali 661

Aleksey Rogov, The University of Manchester
"The role of cathodic current in plasma electrolytic formation of anodic 
coatings"

Apstrakt
Although conventional anodising of aluminium under AC polarisation has 
not demonstrated any benefits in respect to DC processes, a significant 
effect of cathodic current was discovered in high-voltage anodic 
processes, which are usually accompanied by dielectric breakdown of the 
formed films. Such processes are known as Microarc or Plasma 
electrolytic oxidations (MAO/PEO). In special cases, local breakdowns 
(micro-discharges) may promote some interesting coating morphology, 
however, avoiding the stochastic micro-discharging may be beneficial for 
more predictable process control, its efficiency, uniformity of the 
coating on electrodes of complex shape, as well as for design of the 
affordable equipment. A bipolar PEO, when anodic process alternated by 
cathodic pulses, may be softened by extinguishing of the 
micro-discharges though maintaining the coating growth rate and 
formation of the high-temperature phases. However, control of the 
bipolar PEO processes is a challenge due to a lack of its mechanistic 
understanding and difficulties in optimization due to many controlling 
parameters. This talk summarises recent studies on in-situ diagnostics 
of plasma electrolytic oxidation and the role of cathodic current in the 
rational design of anodic coatings on valve metals.