[institut] [phys4phys] Seminar Fizickog fakulteta
Mirzeta Savic
mirzetas at ff.bg.ac.rs
Mon Feb 19 11:28:03 CET 2024
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.
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