Multi-layer coatings
Thermal spray multi-layer coatings combine thermal, mechanical and chemical resistance by tailoring each layer to a specific function. This improves the durability, performance and reliability of components in extreme environments.
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Thermal spray multi-layer coatings offer several advantages over single-layer coatings, including mechanical, thermal and chemical performance. These benefits arise from the combination of materials with complementary properties, allowing the coating to be optimized for specific applications.
1. Improvement of mechanical properties
Better resistance to wear and abrasion
Hard layers (e.g. ceramics, carbides) protect against erosion and wear.
– A metallic intermediate layer can absorb shocks and limit crack propagation.
Better resistance to thermal shocks
– A multi-layer coating can distribute thermal stresses and prevent cracking due to heating and cooling cycles.
– Example: superalloys + ceramics for aircraft turbines.
Optimizing grip
– A first metallic layer (eg: NiCr, CoCr) improves adhesion with the substrate before the application of harder layers.
2. Increased thermal performance
Effective thermal barriers
– An external ceramic layer (e.g. YSZ – yttrium-stabilized zirconia) protects against high temperatures.
– A metallic intermediate layer prevents oxidation and distributes thermal stresses.
– Used in aeronautical engines and thermal power plants.
Reduction of thermal conductivity
– An external insulating layer helps limit heat transfer to the substrate.
3. Protection against corrosion and oxidation
Anti-corrosion barrier
– A layer of NiCrAl or Al₂O₃ can protect against oxidation and chemical corrosion.
– Applications: parts in marine or aggressive chemical environments.
Resistance to chemical attacks
– A multi-layer coating can combine protection against acidity and high mechanical resistance (e.g. carbides + ceramics).
4. Flexibility and adaptation to specific applications
Possibility to adapt properties as needed
– Customized combinations according to the conditions of use (temperature, corrosion, abrasion, etc.).
Various industrial applications
– Aeronautics: turbines, engine blades.
– Energy: components of thermal or nuclear power plants.
– Automotive: wear-resistant pistons and cylinders.
– Medical: biocompatible implants with ceramic layers.