Solving Common Challenges

Abrasion

Abrasion describes the abrasive wear on a surface that occurs when at least two friction partners come into contact. It does not matter whether this is done in a dry, lubricated, damp or even wet environment. The wear mechanism is a micro-cutting process due to scratching stress. The coatings from Praxair Surface Technologies are selected depending on the application for specific abrasion loads.

Corrosion

Corrosion is a progressive loss of material on the surface due to a chemical or electrochemical reaction. There are two manifestations: with and without additional mechanical stress. With additional mechanical load one speaks of stress crack and vibration crack corrosion. Otherwise one speaks, for example, of contact, crevice, intercrystalline corrosion and pitting. The coatings from Praxair Surface Technologies are selected depending on the application for a specific application.

Electric Isolation

Thermally sprayed coatings are ideal for the electrical insulation of metallic components. These components are constructed entirely from the mechanical point of view and the spray layer takes over the electrical insulation. Oxide-ceramic materials are available here, which have high hardness, wear resistance, low thermal conductivity and a high electrical resistance.

Coatings with aluminum oxide can be applied both with the Praxair plasma system and with the Praxair detonation cannon.

Applications:

• Components for interrupting electrical circuits
• Ball-bearing
• Thermocouples
• Components from welding technology
• Corona rollers

Erosion

Erosion occurs, for example, on compressor blades of aircraft engines. The reason for this is the suction of foreign particles, especially in the takeoff and landing phase. In addition, the blades of the compressors are subject to permanent erosion during flight operations due to the dust pollution in the air. The result is a loss of efficiency.

By using Praxair detonation coatings and Praxair Super Detonation coatings on the areas of the blades that are subject to erosion wear, the service life of the blades is significantly extended or high efficiency is maintained over long periods of time.

Non-Stick

In spraying technology, one speaks of a non-stick coating when the layer lowers the adhesive forces between a component surface and a medium surrounding this surface in such a way that this medium does not adhere to the component surface, or does so only to a greatly reduced extent. In principle, a non-stick layer can be provided by a metal or a ceramic coating. Usually, however, the term "non-stick" is used in spray technology in connection with sprayed fluoropolymers such as polytetrafluoroethylene (PTFE). Praxair Surface Technologies coatings are selected depending on the application for specific non-stick requirements.

Non-stick layers from Praxair Surface Technologies ensure a uniformly clean surface that is free of adhesion, even in the event of highly corrosive effects or in contact with adhesive / adhesive media.

Regeneration with the HVOF Process

In the HVOF process, powder particles hit the respective work piece surfaces at supersonic speeds - this enables thick layers with very good adhesion. The component temperature remains below 100 ° C due to cooling. Thus, in addition to steel base bodies, cast materials and non-ferrous metals can be brought back into shape.

The spray coatings consist of nickel or iron-based alloys with microhardness between 28 and 52 HRc. Depending on the hardness, functional surfaces are finished by turning, milling or grinding. In contrast to hard chrome plating, the component size plays a subordinate role, since appropriate functional layers can be applied partially (eg on bearing seats) or on large work piece surfaces. It is often possible to repair the component, including mechanical post-processing, faster than a new production.

Examples of use

• Housing parts
• Sealing seats
• Rollers
• Piston rods
• "Reject rescue" on mechanically incorrectly machined components

Surface Friction

The surface friction largely determines the power transmission between the work piece and the product. The coefficient of friction m provides information as to whether a surface has good sliding behavior or ensures maximum power transmission through a high coefficient of friction. Appropriate coatings from Praxair Surface Technologies optimize surface friction in many industrial applications.

Use of surface friction in the steel industry - In the belt systems of the steel industry, S-rollers are used to transfer the kinetic energy to the steel belt. A coating from Praxair Surface Technologies should be used to ensure maximum power transmission with high wear resistance. By increasing the surface friction by up to 100% compared to an uncoated roll, optimal driving properties of the steel strip can be achieved. This ensures optimal quality for the user over many years.

Thermal Insulation

Components such as combustion chamber parts or turbine blades are exposed to extreme temperatures in gas turbines. Since the unprotected component materials can usually only be used up to approx. 950 ° C, but the manufacturers' requirement is to work with ever higher temperatures, for example to increase the efficiency of the system, these components are provided with thermal insulation layers.

With the plasma processes used at Praxair Surface Technologies, it is possible to apply thermal insulation layers to components with complex geometries in order to achieve the desired properties such as higher component temperature or longer service lives. The adhesion promoter layers can be applied both with the PST-Argon Shrouded Plasma process and with the HVOF-Jet Plate^TM process.

Vibration Wear

Vibration wear (fretting) can occur, for example, on compressor blade roots of industrial gas turbines, since the blades are exposed to a vibration load during operation. In the worst case, this can lead to component failure due to cracks. Downtimes of the entire gas turbine combined with extremely high costs are the result.

Our solution - This is remedied by the CuNiIn layers (anti-fretting layers) applied by the Praxair Surface Technologies - plasma process or detonation process, which due to their excellent damping properties reduce the vibration load on the blade root to a minimum so that catastrophic component failure cannot occur.