THE FASCINATION OF COATINGS

Machines, plants and their components are subject to heavy daily use. Operating hours must be extended and plants should ideally run non-stop. In order to meet demands for productivity and higher performance, equipment must be fortified – against wear, corrosion or heat. This is where coating technology comes into play. It serves as a protective shield against whatever the base material has to endure.

Because no substance or material is able to uniformly meet all requirements, the solution involves dealing with underlying material and surface independently of each other. Requirements are separately defined and then brought together. It is then possible, for example, to develop more cost-effective base materials. In this way, "weak" materials can be made highly durable and soft ones can become extremely hard.

Thermal spraying and deposition welding are two coating processes that offer numerous opportunities for repair and new design of machines/parts or plant systems. In order to promote these two surface coating processes and to make them known to the public, DVS – German Welding Society and GTS (Association of Thermal Sprayers) started a joint initiative called "Faszination Oberflächentechnik" ("Fascination Surface Technology").

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THERMAL SPRAYING

Thermal spraying is a process in which spray materials (in the shape of wire, powder, rod, cord or molten pool) are heated within a spray gun or by a burner and are then "propelled" onto the surface of a pre-treated base material. The surface, which now bears a new coating shot from a "gun", acquires an additional functional property that can protect the base material from wear, corrosion or other "attacks".

Thermal Spraying Process

In applications, different individual thermal spraying processes do not compete directly with each other. Their specific process and coating properties complement each other well. 

“Thermal spraying" is a term used to describe a variety of spraying methods. They are sub-divided according to: 


• The type of spray material (wire, powder, rod, etc.), 

• The mode of application (semi-mechanical, fully mechanical or automated), and

• The type of energy source (thermal or kinetic). 


The exact classification is defined by DIN EN ISO 14917. It differentiates between: 

• Thermal spraying using gaseous or liquid fuels,

• Thermal spraying by expansion of high pressure gases without combustion, and

• Thermal spraying by means of arc or gas discharge.


What it can do

On materials, thermal spraying can ...


• ... optimise, via protection against wear, fatigue and loss of creep strength, corrosion, ageing, abrasion, heat, electrical effects, and leaks,

• ... enable electrical conductivity, and

• ... support biocompatibility.


Where it is applied

Thermal spraying is used in a wide variety of industries. Some examples are:

• Aerospace,

• Construction,

• the automotive sector,

• Energy supply,

• Medical technology,

• the printing industry,

• Water, waste water and waste disposal,

• Textile and clothing manufacture,

• Food processing,

• Mining, and many others


Thermal spraying is a thermomechanical coating method used for new construction as well as repair work. Thermal spraying is flexible, which facilitates a range of possible solutions. Its low repair costs and relatively short downtimes provide serious advantages compared to other maintenance alternatives.


CLADDING

Reliable, economical, fast. That is cladding.

In this coating method, mass volume is built up using a welding filler material (wire or powder) that serves primarily to protect against corrosion and wear.

As with thermal spraying, cladding is usually applied in a localised, targeted manner.

Cladding Processes

Conventional methods of cladding are:


- Gas welding,

- Manual metal arc welding,

- Gas-shielded metal-arc welding,

- Tungsten inert gas welding,

- Plasma arc welding,

- Submerged arc welding,

- Electroslag welding, and

- Laser cladding.


There are three basic types of welding coatings:

- Armouring (against abrasion)

- Plating (against corrosion)

- Buffer layer (for joining two components).



What it can do

Cladding can ...


• ... protect by coating against wear or corrosion and as a result, optimise a material.


• ... perfect or repair the geometry or contour of a part.


Cladding works for new constructs as well as repairs.


Where it is applied

Cladding is used in a wide variety of industries. As examples:


• The construction industry (power plant construction),

• The automotive sector,

• Structural and civil engineering,

• Power generation,

• Mining, etc.


Good examples of successfully welded protective layers can be found on excavator buckets or the impact-shielded areas of stone crushers that, thanks to cladding, can be protected against wear and corrosion in appropriate locations. In addition, potential "attackers" can also arise with crude oil and natural gas extraction in the form of sour gas or rock fragments passed along from the source, or else occur as corrosive chemicals generated in the primary circulation flow of a nuclear reactor.

FASCINATION SURFACE TECHNOLOGY

"Fascination Surface Technology" ("Faszination Oberflächentechnik") is a joint initiative of the Association of Thermal Sprayers (Gemeinschaft Thermisches Spritzen (GTS) e.V.) and DVS - German Welding Society. Its aim is to publicise and promote thermal spraying and deposition welding, the two surface coating processes.

In doing so, it uses the synergy and expertise of the two associations to illuminate the range of applications, properties and advantages of both surface coating processes.

DVS – German Welding Society

DVS - German Welding Society is a technical-scientific society which, encompassing over 120 years of experience, is dedicated to the more than 250 different processes for joining, cutting and surfacing. The heart of all DVS activities is the joint technical-scientific  work. It stands for the persistently close interlinking of contents and results from the fields of research, technology and education. The affiliated companies of DVS process the results from the society and present them to the outside with their own main focal points.

The head office of the society recognised as non-profit-making is in Düsseldorf/Germany. The around 18,000 members are looked after directly in situ by the DVS state branches and the DVS district branches. Together, all the members of the society are committed to joining technology suitable for the future in every respect.

GTS e.V.

The Association of Thermal Sprayers (Gemeinschaft Thermisches Spritzen (GTS) e.V.) is an association for all users and proponents of thermal spraying that are open to the European idea. The primary goals of the GTS founders were to educate the broad industrial community on thermal spraying technology, promote thermal spraying practice and research in coordination with the DVS – German Welding Society, and assist all of its members in industrial commercialisation of the technology.

A collaborative activity of GTS is to represent the market-political interests of its members and, if required, implement them. High quality coatings and corresponding quality assurance are always a priority.

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