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Plasma electrolytic oxidation
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<p>Plasma electrolytic oxidation (PEO), also known as electrolytic plasma oxidation (EPO) or microarc oxidation (MAO), is an <a href="/facts/Electrochemistry/C0RUWpBH">electrochemical</a> <a href="/facts/Surface_treatment/Udeh3cxF">surface treatment</a> process for generating <a href="/facts/Oxide/DXtoVe1C">oxide</a> <a href="/facts/Coatings/fGt3R3VC">coatings</a> on <a href="/facts/Metals/PT8hNX6R">metals</a>. It is similar to <a href="/facts/Anodizing/06Njuj3v">anodizing</a>, but it employs higher <a href="/facts/Electric_potential/Nmqm6hm5">potentials</a>, so that <a href="/facts/Electrostatic_discharge/I55BBYfS">discharges</a> occur and the resulting <a href="/facts/Plasma_(physics)/1d3btMVU">plasma</a> modifies the structure of the oxide layer. This process can be used to grow thick (tens or hundreds of micrometers), largely <a href="/facts/Crystalline/e2R2mk3E">crystalline</a>, oxide coatings on metals such as <a href="/facts/Aluminium/7wmR8jYE">aluminium</a>, <a href="/facts/Magnesium/XyIhd2FG">magnesium</a> and <a href="/facts/Titanium/53ArnDoy">titanium</a>. Because they can present high <a href="/facts/Hardness/PtGn6E20">hardness</a> and a continuous barrier, these coatings can offer protection against <a href="/facts/Wear/2PxRQ1Ke">wear</a>, <a href="/facts/Corrosion/lIC7H4we">corrosion</a> or heat as well as <a href="/facts/Electrical_insulators/SfSXkrh5">electrical insulation</a>. </p> <p>The coating is a <a href="/facts/Oxidation/Pyd5RVcj">chemical conversion</a> of the <a href="/facts/Substrate_(materials_science)/LwwkV6rX">substrate</a> metal into its <a href="/facts/Oxide/DXtoVe1C">oxide</a>, and grows both inwards and outwards from the original metal surface. Because it grows inward into the substrate, it has excellent <a href="/facts/Adhesion/NuVQPk4z">adhesion</a> to the substrate metal. A wide range of substrate alloys can be coated, including all wrought aluminum alloys and most cast alloys, although high levels of silicon can reduce coating quality. </p>