How to choose the Best Coating System
For selecting the most appropriate coating system, different criteria should be
taken into consideration, such as:
- Maintenance type and strategy (predictive or corrective)
- Wear resistance and thickness of coatings
- Mechanical properties of coatings (pressure, impact, temperature)
- Corrosion resistance of coatings
- Surface position during the coating procedure
- Amount of heat input during coating
- Necessity for preheating or postheating
- Repairability of coatings
Price/efficiency ratio, economic priorities and specific needs are other
important criteria for decision making.
Furthermore, for repair coating it is of interest to know if dismantling is
necessary or if in situ repair is possible.
Coating selection:
![Procedure for coating selection](img/processes/choixe.png)
Procedure for coating selection
Wear mechanisms
- Friction / adhesion
- Abrasion
![Abrasion](img/wear/abrasion.jpg)
Abrasion
![Erosion: Heavily worn Pelton wheel](img/industry/pelton380.jpg)
Erosion: Heavily worn Pelton wheel
![Cavitation: Agitator propeller](img/wear/cavitation.jpg)
Cavitation: Agitator propeller
![Surface Fatigue: Tread of wheel (railway)](img/wear/surfacefatigue.jpg)
Surface Fatigue: Tread of wheel (railway)
![Combined wear: Hot working die](img/wear/combinedwear.jpg)
Combined wear: Hot working die
Systematic wear analysis
- Design properties
- Base body (initial stage)
- Opposing body / Intermediate body
- History
- Base body (final stage)
- Special parameter / properties
Corrosion mechanisms
![Different types of corrosion](img/corrosion/schemae.png)
Different types of corrosion
- Wet corrosion - without mechanical stress
![Uniform corrosion](img/corrosion/gleichmkorr.jpg)
Uniform corrosion
![Crevice corrosion](img/corrosion/spaltkorrosion.jpg)
Crevice corrosion
![Pitting corrosion](img/corrosion/lochfrassansatz.jpg)
Pitting corrosion
- Wet corrosion - with mechanical stress
![Stress corrosion,<BR>
Microsection](img/corrosion/stress.jpg)
Stress corrosion,
Microsection
![High temperature corrosion<BR>
combined with erosion,<BR>
Stainless steel,<BR>
Drying plant - Cement work](img/corrosion/oxydation.jpg)
High temperature corrosion
combined with erosion,
Stainless steel,
Drying plant - Cement work
Hardness test
The hardness tester forces a small sphere (Brinell, HB), a diamond pyramid (Vickers, HV)
or a cone (Rockwell C, HRC) into the surface of a metallic material.
![Hardness tests](img/metallurgy/hardness1en.png)
Hardness tests
Tensile strength N/mm2 |
|
Vickers HV |
|
Brinell HB |
|
Rockwell C HRC |
720 |
|
225 |
|
214 |
|
--- |
800 |
|
250 |
|
238 |
|
22.2 |
880 |
|
275 |
|
261 |
|
26.5 |
985 |
|
300 |
|
285 |
|
29.8 |
1125 |
|
350 |
|
333 |
|
35.5 |
1290 |
|
400 |
|
380 |
|
40.8 |
1485 |
|
460 |
|
437 |
|
46.1 |
1665 |
|
510 |
|
---- |
|
49.8 |
1845 |
|
560 |
|
---- |
|
53.0 |
2039 |
|
610 |
|
---- |
|
55.2 |
2180 |
|
650 |
|
---- |
|
57.8 |
------ |
|
700 |
|
---- |
|
60.1 |
------ |
|
800 |
|
---- |
|
64.0 |
------ |
|
900 |
|
---- |
|
67.0 |
Thermal conductivity
![Thermal conductivity](img/wear/thermalconductivitye.png)
Thermal conductivity
For further information, on-site training, technical advise or project management, please do not hesitate to
contact us.
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