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Example of a plasma oxidated part    PulsPlasma® Oxidation
Process Description

Oxide layers on steel components are growing in importance in engineering because they:

    Offer outstanding corrosion protection
    Enhance wear and tribological resistance
    Enhance surface coefficient of friction requirements
    Improve surface cometic appearance with a dark grey to black surface colour


The oxide layers produced by plasma oxidation are comparable with those from other nitriding processes and have the following properties:

    Black colour
    Thickness of approx. 1 µm
activation, construction and building of plants wettability, coating, bipolal pulse, technology ,thin films, degreasing, Gas nitriding, hardening, hard coatings, hydrophil, hydrophob, corrosion, corrosion protection, plastic surfaces, nitriding, nitrocarburizing, surface technology, surface refinement, surface hardening, oxidizing, PA CVD/PE CVD coating, plasma, plasma activation, plasma, power supply, plasma hardening, plasma nitriding, plasma plant, plasma oxidizing, plasma polymerisation, plasma cleaning, plasma sterilising, plasma technology, polymerization, pulsed plasma, cleaning, life standing time, sterilizing, power supply, TiCN coatings, TiC coatings, TiN coatings, vacuum plants, agglutinate, wear, wear protection, heat treatment, tool hardening    Chemical composition F3O4 (magnetite)

In order to produce oxide layers, the component is first plasma nitrided. For this, the parts are placed into a vacuum vessel which is electrically isolated from the support housing. At a pressure of 100 - 500 Pa, a pulsating electric DC voltage of several hundred volts is applied between the workpieces and the vessel wall with the workpiece connected as the cathode. A high-current glow discharge then develops by ionisation of the process gas in the vessel.
Positively charged nitrogen ions are accelerated towards the workpiece and diffuse into the workpiece surface. The treatment temperatures during nitriding are in the range from 500 to 550° C (930° F - 1022° F). For the subsequent oxidation it is necessary to produce a thick compound layer (5-10 µm); this can be achieved by an appropriate choice of process parameters and gas composition.


The plasma oxidation takes place immediately after the nitriding without the need to interrupt the running process. Physically the same process take place during oxidation in the plasma as during nitriding, except that the process gases are changed and the process parameters are adapted. The oxidation step takes around 30 minutes and follows the nitriding treatment immediately; it can be precisely controlled with respect to the layer buildup.


In many areas of machine engineering, oxide layers are compared with other coatings, such as the hard chrome plating of hydraulic cylinders in the hydraulic industry. In such cases the corrosion resistance of the oxide layer is normally higher than that of the hard chrome plating with only half the coefficient of friction with dry friction.

 
 

PlaTeG GmbH
A Company of the PVA TePla Group
Postfach 210642
57030 Siegen
Deutschland / Germany

Managing Directors: Dr. Reinar Grün ; Arnd Bohle
Amtsgericht Siegen, HRB 8070  ;  USt.Id. DE 814730669
e-mail: service@plateg.de

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