As an indirect assessment of the saturation of European industry in equipment for the plasma / gas thermal coating above the saturation of Russian enterprises in 350-400 times. Example. Abroad 75% of valves (ball valves of large diameter) is coated with tungsten carbide for bonded cobalt-chromium, and the rest – with a galvanic deposition of chromium or nickel. We have the 100% ball valves of the same size have the galvanic coatings. The most widely used plasma technology in the U.S. (“Caterpillar”, “Eastern Airlines”), Germany (“Daimler Benz”, “Bosch”), England (“Beanz Indastrinz Limited”, “Lucas”, “Parkins”) also found in the repair and restoration of parts of technological equipment, which significantly reduces production costs.
- Plasma – a gas state, where it is heated to 6000-30000 ° C.
- The device that generates, supports and guides the plasma to the workpiece, is called a plasma generator.
- When applying a jet of gas escaping from the plasma generator, the powder of any material having a melting phase, there is virtually instantaneous melting of the material. Moving in the gas stream at a speed of 200-2000 m / s in the direction of a specially prepared surface of the product, a drop of material, partially welded to it and partly welded to each other, forming a solid coating.
The deposition on the surface of the product in the plasma jet of molten material called plasma spraying.
So, get coverage from any of the metals and alloys, ceramics, cermets (metal-ceramic materials), plastics, any functional properties – super-strong, durable, anti-friction, chemically stable (acid-resistant to salts, acids, petroleum products), anti-corrosion, decorative etc.
The temperature at the surface of the product in the process of spraying coating is provided within no more than 100-150 C, which eliminates warping, structural and phase changes in metal products.
The thickness of the deposited plasma coatings is mainly 0,1-1,0 mm, while for ductile materials, such as babbit (in the recovery of the geometry of babbit bearings bearings, babbit seals) and polymers (for application of anticorrosion coatings), can be more than 1,5 mm.
When creating the conditions for surface melting of the metal parts will be the saturation of the surface layer, paid in the plasma material, plasma deposition process.
With the help of plasma surfacing metal powder can be heat-resistant and most durable coatings of alloys based on nickel and cobalt. This method allows you to get thin, even coating with a smooth surface, often requiring no additional machining.
In addition, the plasma arc gives a minimum depth of penetration and a minimum proportion of the base metal in the weld, which is a major technological advantage of the plasma deposition compared with other methods of welding.
The temperature at the surface of the product in the process of surfacing coating is provided within 1000-1500 ° C.
The thickness of the plasma clad coatings mainly of 0,5-4,0 mm.
Strength of the bond coating to the base (adhesion) – corresponds to the strength of foundations, which allows products to operate with the deposited coatings under shock and high contact loads (eg, edge molds).
Overlay nonporous solid.
The advantages of plasma protective coating over the other (galvanic, vacuum, oxygen-acetylene, etc.) are as follows:
- The high temperature plasma flow can melt and cause the most refractory materials;
- The flow of plasma makes it possible to obtain alloys of different material properties or to apply multilayer coatings of various alloys. It opens wide the possibility of obtaining coatings, which combine a variety of protective properties;
- Features of this method is not limited to the shape and size of workpiece;
- Plasma arc – the most flexible source of heat, allowing a wide range to adjust its energy characteristics, providing a coating with a melting point of 200 ° C, for example, polymer coatings, to 2500-3000 o C – various ceramic materials