Flammspritzstrahl, Drahtflammspritzen mit Molybdaen

Spraying processes

Wire flame spraying ( WFS )

For more information please go to Fischer-Wesnigk.de

When wire or rod flame-spraying the consumables are continuously melted in the centre of an oxygen-acetylene flame. By means of atomizing gas, i.e. compressed air or nitrogen, the spraying particles in the shape of droptlets are removed from the melting area and are accelerated onto the prepared work surface. Wire flame spraying is a common process with a very high quality standard of the sprayed coating.


Powder flame spraying ( PFS )

For more information please go to Fischer-Wesnigk.de

When powder flame spraying the spraying consumables in powder form are melted onto the prepared surface in an acetylene-oxygen flame and are accelerated by means of the expanding combustion. If necessary an additional gas (i.e. argon or nitrogen) can be used for acceleration of the powder particles. There is a wide and diversified range of more than 100 spraying consumables in powder form available. You distinguish the powders between self-fluxing and self-bonding spray powders. The self-fluxing ones mostly require an additional thermal finishing-treatment. This “melting-process” is mainly carried out with the suitable acetylene-oxygen torches. You achieve a considerable increase of bonding of the sprayed layer on the base material; the sprayed surface is gas- and liquid-proof.


Arc spraying ( AS )

For more information please go to Fischer-Wesnigk.de

When arc spraying 2 spraying wires of the same or different kinds are melted in an arc and are sprayed with atomizing gas i.e. compressed air onto the prepared surface. Arc spraying is a high-performance spraying method with the use of wire. You can only spray electrically conductive materials. Use of nitrogen or argon as an atomizing gas will prevent oxidisation of the materials to a large extent.


High Velocity Oxygen Fuel Spraying ( HVOF )

For more information please go to Fischer-Wesnigk.de

In the HVOF-spraying process a continuous gas combustion with high pressures is carried out in the combustion chamber. In the central axis spraying consumables in powder form are fed into.
The required high flow velocity in the gas jet is generated by the high pressure of the fuel gas and oxygen mixture in the combustion chamber as well as the subordinated expansion nozzle. In this process the spraying particles are accelerated to a high particle velocity that results in highly dense sprayed coatings with excellent adhesive properties. Caused by the sufficient but moderate temperature as part of the spraying process the spraying consumables will only slightly change metallurgically, i.e. minimal forming of composite carbide. With this technique extremely thin coats with a high grade of accuracy will be achieved. As combustion gases propane, ethylene, acetylene and hydrogen can be used.


Cold Gas Spraying ( CGS )

For more information please go to Fischer-Wesnigk.de

Cold Spraying, in this coating process a certain type of gas, e.g. nitrogen is accelerated to extremely high velocities. Then the required material in powder form will be added. By Cold Spraying the spraying particles hit the substrate at supersonic speeds and achieve a very dense strong bonding surface through the enormous kinetic energy. The created coating characteristics are nearly no different from the original material. Pores do not exist.

For more information: www.kaltgasspritzschicht.de

Plasmaspraying ( APS )

For more information please go to Fischer-Wesnigk.de

In contrast to the thermal spray techniques with flame or arc where the temperatures reach between 3000 and 4000° C Plasma Spraying stands out through the temperatures that are reached.
In Plasma that you achieve through ionization of gases like argon or hydrogen exist temperatures of about 20,000 °C. Therefore this process is outstandingly appropriate for using materials with a high melting point. Only in the Plasma beam ceramic powders can be melted to achieve a dense, highly adhesive coating.
Only in the Plasma beam ceramic powders can be melted to achieve a dense, highly adhesive coating. All other spraying methods are unsuitable for this.
Regarding metals first of all tungsten should be mentioned which only can be processed by plasma spraying because of its melting point of 3,400 °C. Tungsten coatings are acid-resistant and combustion-proof.