KEPLA-COAT®

KEPLA-COAT® is a plasma chemical coating that improves aluminium and titanium alloys. In the case of titanium alloys the process was earlier referred to as Plasmocer®.

Coating takes place in a saline solution electrolyte. The workpiece is connected in series to an external source of electricity and acts as an anode. During anodisation oxygen plasma discharges itself on the workpiece surface and briefly melts the surface thus forming 2 oxide ceramic layers that bond tightly with the outer metallic layer. A barrier layer with a thickness of about 100 nm constitutes the direct bond with the aluminium or titanium workpiece. Then come an oxide ceramic layer with low porosity density followed by one with high porosity density. This layer bond protects the aluminium and titanium against wear and corrosion and, thanks to its surface structure, it allows the absorption of lubricants as well as following workpiece treatments such as, for instance, paintwork or impregnation.

Grafik

With the process variant KEPLA-COAT® black all common aluminium and titanium materials can be coated. KEPLA-COAT® black can be used for optical devices, fine pitch thread or heat radiators. 

KEPLA-COAT® layers applied to aluminium consist of up to 60 percent of corundum. The remaining layer components are mainly Al2O3 and boehmite. Depending on the alloy of the coated workpiece, KEPLA-COAT® can reach a thickness of up to 150 μm. The layer thickness of structural aluminium components usually ranges from 40 to 60 μm. KEPLA-COAT® provides not only excellent wear protection, but also perfect uniform layer, dimensional accuracy and hardness. KEPLA-COAT®-coated substrates show a much greater fatigue strength than substrates with similar layers. These layers can resist aggressive gases such as chlorine and boron trichloride and a layer thickness of 30 μm, for instance, shows a corrosion resistance of more than 3,000 hours in the salt fog test according to DIN EN ISO 9227. In addition, KEPLA-COAT® ensures extremely good anti-friction properties in combination with PTFE or other dry lubricants.

Sliding wear test

Sliding wear test text

Stress number curves

Stress number curves text

(All technical values published here are subject to the test conditions specified. We therefore emphasise that the applications and operating conditions, along with the end user's practical experience, will ultimately determine the level of performance achieved by the coating and/or coating system.)

The KEPLA-COAT® plasma chemical process is well suited for the coating of aluminium and titanium alloys*.

*The process KEPLA-COAT® white for titanium materials, we have currently not in use. Please contact us regarding a possible project handling.

KEPLA-COAT®-coated aluminium components have a wide variety of applications: for instance, geometrically high-precision rotors in turbo molecular pumps. In this case, the workpiece's layer without any cracks or pores at all prevents the infiltration of reaction gases and it provides the necessary protection for plasma etching processes while resisting the mechanical stress generated by the extremely high rotation speed.

KEPLA-COAT®-coated aluminium components are used, among other things, as sealing gaskets, fixing discs, cylinders, drums or cylindrical tubes.

  • Aerospace
  • Automotive industry
  • Communications technology
  • Medical technology
  • Data processing
  • Optics and electronics
  • Vacuum technology
  • Food processing industry

Process Variant KEPLA-COAT® black

KEPLA-COAT® black can be used to coat all commonly used aluminium- and titanium-based materials. The usual layer thickness values lie within the 5 to 15 μm range for aluminium-based materials and at maximum 10 μm for titanium-based materials. Owing to the layer's crystalline structure the base material's fatigue strength is only slightly affected. KEPLA-COAT® black is suitable, for instance, for optical components, high-precision screw threads or heating radiators. This coating is used in sectors like vacuum technology, microelectronics and the aviation and space industry.

Sealed 10-μm-thick black KEPLA-COAT® layers can withstand a test period of over 1000 h in the salt spray chamber according to DIN EN ISO 9227 / DIN EN ISO 10 289.

An initial roughness of Ra= 0.14 μm is transformed after coating with 10 μm KEPLA-COAT® black into a roughness value of Ra= 0.5 μm.

The outgassing rate of the KEPLA-COAT® black layer amounts to 10-6 Pa• l • s-1 • cm-2  under specific vacuum conditions with scarce traces of H2O in the residual gas.

KEPLA-COAT® black layers for titanium materials can resist to temperatures up to 700°C.

Layer
(Thickness) 
Degree of Absorption α Degree of Reflection ρ Colour DifferenceBrightnessEmissivity ξ 
KEPLA-COAT®
black for Al (8 μm) 
> 95 % ≤ 5 % 29 % 30 % 65 %
KEPLA-COAT®
black for Ti (8 μm) 
> 95 % ≤ 5 % 25 % 15 % 80 %

Remarks:

Absorption coefficient, reflection, colour difference, and brightness were determined at room temperature and within the visible range. The colour difference indicates the degree of blackness (0 % = theoretically absolute black, 100 % = absolute white). The emissivity was determined at 85°C and it refers to emissions in the infrared range.

(All technical values published here are subject to the test conditions specified. We therefore emphasise that the applications and operating conditions, along with the end user's practical experience, will ultimately determine the level of performance achieved by the coating and/or coating system.)