Plasma Electrolytic Oxidation
A revolutionary surface engineering process that transforms light alloy surfaces into hard, dense ceramic coatings.
PEO operates at voltages far beyond conventional anodising, generating micro-plasma discharges that build a robust, adherent oxide layer from the substrate outward.
What is Plasma Electrolytic Oxidation?
Plasma Electrolytic Oxidation (PEO), also known as Micro-Arc Oxidation (MAO), is an advanced electrochemical surface treatment technology. Unlike conventional anodising, PEO applies voltages beyond the dielectric breakdown point of the oxide film, generating plasma micro-discharges at the metal surface. These plasma events transform the base metal into a complex, multi-phase ceramic oxide coating with exceptional mechanical and chemical properties.
Ceramic Coating Process
The substrate is immersed in an aqueous electrolyte solution and subjected to high-voltage alternating or pulsed DC current. At voltages typically between 200–700V, local plasma discharges ignite across the surface, creating temperatures of several thousand degrees Celsius in micro-zones. This sintering process converts the native oxide layer into crystalline phases—primarily alpha and gamma alumina—with densities approaching theoretical maximum.
Surface Enhancement
PEO coatings are grown from the substrate itself, ensuring metallurgical bonding rather than mechanical adhesion. The resulting ceramic layer is three to five times harder than conventional hard anodising, with hardness values of 1200–2000 HV. The porous outer zone can be sealed or impregnated with functional materials to tailor friction, lubricity, or thermal properties for specific applications.
Environmental Advantages
PlasmaOx's PEO process uses environmentally benign aqueous electrolytes free from hexavalent chromium, heavy metals, and hazardous organic compounds. The process produces no toxic sludge and generates minimal waste, meeting REACH, RoHS, and ELV directives. The longevity of PEO coatings reduces lifecycle replacement frequency, further reducing the environmental footprint of treated components.
Manufacturing Process
Components are cleaned, jigged, and immersed in our proprietary electrolyte baths. Computerised power supply units deliver precision-controlled waveforms to achieve coating uniformity across complex geometries. Real-time process monitoring ensures coating thickness, phase composition, and properties meet specification. Post-process quality verification includes hardness mapping, thickness measurement, salt spray testing, and XRD phase analysis.
How PlasmaOx Compares
See how our advanced PEO technology outperforms conventional coating methods.
| Property | Plasma Spray | Alumina Anodising | Traditional PEO | PlasmaOx Advanced PEO★ Best |
|---|---|---|---|---|
| Hardness (HV) | 400–600 | 200–400 | 800–1200 | 1200–2000 |
| Coating Thickness (μm) | 100–500 | 10–25 | 5–150 | 5–200 |
| Adhesion | Mechanical bond | Good | Metallurgical | Metallurgical |
| Corrosion Resistance | Moderate | Good | Excellent | Exceptional |
| Environmental Impact | High | Moderate | Low | Minimal |
| Complex Geometry | Difficult | Good | Excellent | Excellent |
| Temperature Resistance | Moderate | Low | High | Very High |
| Process Control | Manual | Semi-automated | Automated | Full digital control |