During the Keronite Plasma Electrolytic Oxidation / Micro Arc Oxidation process (PEO / MAO), a modulated electrical current is passed through a bath of proprietary Keronite electrolyte solution. Parts are suspended from a bus bar and submerged in the chrome-free, low concentrate alkaline electrolyte inside a stainless steel electrode cage. Different electrolytes are required for the protection of aluminium and magnesium surfaces or new electrolytes can be designed to meet specific customer requirements, but all are chrome-free and contain no other heavy metals, ammonia or any acids.
As the pulsed alternating current is passed through the Keronite Plasma Electrolytic Oxidation bath, a controlled plasma discharge is formed and sparks are generated on the substrate surface. This plasma discharge converts the surface of the aluminium or magnesium substrate into a complex ceramic coating by:
- Plasma Electrolytic or Micro Arc Oxidation of the surface
- Elementary co-deposition
- Fusion of the ceramic layer
Because of the insulating nature of the Keronite ceramic coating, the process is somewhat self-regulating and impressive uniformity of coating thickness can be achieved if required, unlike many conventional electroplating processes. As an immersion process, Keronite Plasma Electrolytic Oxidation has much greater throwing power than plasma sprayed ceramic or other line-of-sight processes. Aluminium or magnesium parts can be selectively treated by masking, or greater protection can be provided in critical areas by focussing the growth of the ceramic coating accordingly.
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