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Plasma chemical coatings

Plasma chemical coatings

Finishing of light-weight metals.

What characterizes these coatings?

What characterizes these coatings?

We are talking about oxide-ceramic coatings characterized by accurate depositions and good bending fatigue strength.

Plasma coating is a process that creates oxide-ceramic layers characterized by accurate depositions. These hard coatings are furthermore characterized by good bending fatigue strength. With MAGOXID-COAT® and KEPLA-COAT®, Aalberts surface treatment offers you two anodic plasma-chemical surface finishes with functional characteristics profiles, the total of which cannot be achieved with electroplated coatings. MAGOXID-COAT® is used on magnesium alloys, whereas KEPLA-COAT® is used for the finishing of materials made from aluminum and titanium alloys. The plasma-chemical process creates oxide-ceramic coatings which, apart from offering wear and corrosion protection, also fulfill further requirements, such as hardness, even layer structures, fatigue strength, dimensional accuracy and thermal endurance. Edges, cavities and reliefs are evenly coated, i.e. that there is no edge formation as is the case during electroplating.

Electrolytic processes are performed with the help of an external power source, while the workpiece to be coated is used as the anode. The workpiece surface is converted into oxides, while saline solutions are used as electrolytes. Anodic coatings are created in the electrolyte by plasma discharges on the surface of the part to be coated.

KEPLA-COAT® as plasma treatment

KEPLA-COAT® is a plasma-chemical anti-wear coating solution for aluminum and titanium alloys. In the past, the process used for titanium alloys was referred to as Plasmocer®. The process is performed at our Berlin location, the competence center for plasma-chemical processes.

This is how our KEPLA-COAT® coating process works

The coating with KEPLA-COAT® takes place in an aqueous organic electrolyte. The workpiece is connected to an external power source as an anode. In the process of anodization, oxygen plasma discharges onto the workpiece surface, melting it for a short time and forms an extremely thin barrier layer at first, which firmly bonds to the outer metal layer. This is followed by a low-pore and then a high-pore oxide ceramic layer. The color of the layers is usually grey-white. However, black layers can be produced as well.

Properties of KEPLA-COAT® coatings

Plasma chemical coatings

This multilayer composite coating protects aluminum and titanium against wear and corrosion. Its surface structure allows lubricants to be easily absorbed and subsequent workpiece treatments, such as varnishing or impregnations, to be performed.

Apart from excellent wear protection, KEPLA-COAT® offers absolute contour accuracy, dimensional accuracy and hardness. The fatigue strength of substrates coated with KEPLA-COAT® is significantly higher than that of substrates finished with similar coatings. The coating is able to withstand aggressive gases, such as chlorine and boron trichloride. KEPLA-COAT® also offers excellent gliding properties, especially in combination with PTFE or other dry lubricants.

Suitable base materials

Be it wrought alloys, cast alloys or die casting alloys, KEPLA-COAT® is suitable for almost all technically interesting aluminum alloys. It is also possible to coat titanium materials. White coatings cannot currently be created on titanium materials. Please get in touch with us if you have any questions with regard to the possible implementation of projects concerning this matter.

Fields of application of KEPLA-COAT®

Aluminum components coated with KEPLA-COAT® are suitable for a wide variety of applications: They are used, for instance, on geometrically complex rotors in turbomolecular pumps. On the one hand, the crack and pore-free coating keeps reaction gases from penetrating into the workpiece, thus providing the requisite protection against plasma etching processes; on the other hand, it is able to withstand the mechanical loads produced by extremely high rotational speeds. Aluminum workpieces coated with KEPLA-COAT® are also used as sealing rings, fixing washers, rollers, drums or cylinder tubes. Due to their high light absorption capacity, black KEPLA-COAT® layers are suitable, for example, for optical parts, fine threads or heat radiators.

The areas of application stretch from coatings in the automotive industry to the following sectors:

  • Data processing
  • Electronics
  • Energy technology
  • Communication technology
  • Food industry
  • Aerospace industry
  • Optical industry
  • Mechanical engineering
  • Medical devices
  • Vacuum technology

MAGOXID-COAT® as a plasma coating process

MAGOXID-COAT® is a plasma-chemical coating for the finishing of magnesium alloys. This coating process is also performed at our Berlin factory, the competence center for plasma-chemical processes.

This is how our MAGOXID-COAT® coating process works

Coating with MAGOXID-COAT® is carried out in an electrolyte of salt solution using a high electrical voltage, similar to the KEPLA-COAT® process. This involves an charge exchange through the natural barrier layer of magnesium and at the same time a diffusion of magnesium ions towards the outer reaction zone. This process is associated with the forming of punctiform heat sources on the anodically connected magnesium. Plasma-chemical processes occur in the form of gas discharges on the magnesium surface, which is hence oxidized. The color of the layers is usually white-grey. As with the KEPLA-COAT® process, black layers can be produced as well.

Properties of MAGOXID-COAT® coatings

Plasma chemical coating magnesium alloy

MAGOXID-COAT® multilayer composite coatings protect magnesium alloys against wear and corrosion. Their surface structure allows lubricants to be easily absorbed and subsequent workpiece treatments, such as varnishing or impregnations, to be performed. The plasma-chemical process creates a crystalline oxide-ceramic layer and thus a strong anti-corrosion coating which also fulfills further requirements, such as hardness, contour accuracy, bending strength, dimensional accuracy or thermal endurance.

Suitable base materials

The MAGOXID-COAT® process is suitable for all common magnesium alloys, such as AZ31, AZ61, AZ81, AZ91, AM20, AM50 or AM60, as well as for alloys containing rare earths and zirconium, such as ZE41 and WE43.

Fields of application of MAGOXID-COAT®

When it comes to construction materials, magnesium is the lightest metal. MAGOXID-COAT® ideally combines the versatility of magnesium materials with a wide range of coating properties. Thus, this type of coating allows treated magnesium products to be used in many different areas. Magnesium components are coated with MAGOXID-COAT® white in order to protect them against wear and corrosion. Subsequent varnishing, e.g. on wheels for sports cars, bicycles and wheelchairs, is possible without any problems. Due to their high light absorption capacity, black MAGOXID-COAT® layers are suitable, for example, for optical parts, fine threads or heat radiators.

These coatings are used, inter alia, in the following industries:

  • Automobile construction
  • Armature manufacturing
  • Office technology
  • Data processing
  • Energy technology
  • Household appliances industry
  • Communication technology
  • Food industry
  • Aerospace industry
  • Optical industry

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