Anodic oxidation ("anodizing") is a process for creating an oxidic protective layer on aluminum or titanium. This process does not actually apply a protective layer on the material, but creates a thin oxide layer by converting the top metal layer.
The conversion is done after chemical preparation (degreasing, corroding) by means of electrolysis. Hydrogen and water are created at the cathode, and aluminum is oxidized to aluminum oxide at the anode. The result is a thin layer of 5 - 25 µm, which ensures good protection against corrosion and wear resistance. Depending on the oxidation conditions and the choice of electrolyte, aluminum alloys of various hardness levels can be created, which can be used for corrosion protection or decorative purposes.
With its low density (2.8 g/cm3), aluminum, in conjunction with CompCote®, opens up new approaches in technical and decorative applications with increased requirements on quality. CompCote® is a polymer-aluminum oxide composite coating with revolutionary properties. In addition to the CompCote® process, there is also "CompCote®-H". CompCote®-H offers better hardness characteristics and better wear and corrosion properties.
CompCote® is free of heavy metals, fluoropolymers and PVC. The procedure is patented in Europe, the USA and other countries and is classed as food-safe by the American Food & Drug Administration (FDA).
Layer structure, layer thicknesses and tolerances
CompCote® is formed by transforming the substrate and therefore guarantees optimal bonding. CompCote® grows in the substrate and out of it too. CompCote® layers are formed through anodic oxidation of the base material and simultaneous molecular bonding of the aluminum oxide layer with polymers. In contrast to the conventional anodization procedure, anodization with the CompCote® process creates a surface with a cellular structure.
Due to the molecular polymer content, CompCote® forms chemical bond bridges when a coordinated top coat is selected. This achieves a better adhesive strength.
The optimal solution for your specific application
Examples of applications where CompCote is successfully used:
Architecture, the automotive industry, electrical engineering, photo and video technology, household appliances, hydraulics, information technology, hunting weapons, the food industry, aviation, mechanical engineering, medical technology, pneumatics, sports articles, packaging machines, defense technology
Hardness & wear protection
CompCote® forms an extremely hard aluminum oxide (1200 HV). However, as with all anodic oxidation layers, only the "apparent hardness" is measured as the layer hardness. This value is between 300–600 HV depending on the alloy and the procedure.
CompCote® is over 3x and around 1.5x more wear resistant than anodic and hard-anodic (hard coat) oxide layers (Taber Abraser Test /MIL A 8625F). Results from the Taber Abraser Test show a significant reduction in the abrasion rate with the CompCote® procedure.
CompCote® replaces chromic acid layers: Thin chromic acid layers (2.0 ?m) are known for their good properties under alternating bending stress, which is why they are used in the aviation industry. CompCote® performs even better in this field, as it has no impact on the alternating bending stress resistance of the base material. It also outperforms chromic acid layers in corrosion resistance tests.
CompCote® is considerably tougher and break-proof: CompCote® shows a fibrous fracture pattern in notch impact tests. Conventional oxidation layers, on the other hand, have a brittle fracture pattern like glass.
In various pairings and friction tests, CompCote® shows very good anti-scuffing properties. In some cases, the friction values even reduce in repeat tests (self-smoothing effect). Stick-slip effects are reduced.
CompCote® is corrosion-resistant and outperforms conventional anodizing layers in corrosion tests (salt spray test / ASTM B117).
Nucocer® AL coatings are produced in plasma-chemical oxidation processes. They have a finely crystallized ?-AL2O3 structure and an amorphous zone in the upper part.
|Maximum layer thickness:||300 µm|
|Standard layer thickness:||70-120 µm|
|Coating thickness (depending on the alloy):||1200-2000 HV 0.01|
Nucotec® EL layers are made from hard, wear resistant aluminum oxide. They are formed through the chemical reaction that turns aluminum into aluminum oxide. This results in excellent adhesion to the base material. Nucotec® EL layers "grow" out of the base material by around 1/3 of the layer thickness.
Nucotec® HE layers are made from extremely hard, wear resistant aluminum oxide. They are formed through the chemical reaction of the aluminum material in special cooled acid electrolytes. The transformation results in excellent adhesion between the base material and the hard oxide protective layer.
Nucotec® HE layers are much more compact than conventionally produced anodic oxidation layers (anodized layers) and are therefore significantly more resistant to wear and corrosion.
Due to the micro-porous properties, only the "apparent hardness" is measured. This value is between 300 – 600 HV0.025 depending on the alloy. The thermal conductivity is around 10% of the base material, the electrical dielectric strength is max. 20 V/µm (Nucotec® HE-Cu and Nucotec® HE-GD) or max. 30 V/µm (Nucotec® HE).
The optimal solution for your application
|Process type||Material (selection)||Product example|
|Nucotec® HE AL||AL wrought and cast alloys, e.g. AlMg3, AlMgSi1;, AlMGSiPb, AlZnMgCu, G-AlMg5;, G-AlSi10Mg||Precision turned parts, cylinder liners, pump impellers, air bearings, control pistons, pneumatic valves, heating plates, injection molding tools, machine parts|
|Nucotec® HE-Cu||Al wrought and cast alloys with a high copper content, e.g. AlCuMg1, AlCuMgPb, AlCuBiPb, G-AlSi9Cu3, G-AlSi6Cu4, AlCu4Ti||Precision turned parts, motor parts, machine parts, rolls, coils, bearing parts, valves|
|Nucotec® HE-GD||Al die-casting alloys, e.g. GD-AlSi9Cu3, GDAlSi10Mg, GD-AlSi12, GD-AlMg9Si||Hydraulic cylinders, pump housings, motor pistons, machine parts, coupling parts|