Industrial Gas Turbines

Components – Castolin Eutectic workshop in UK, Newcastle has the capability to apply a range of coatings for the Gas Turbine sector:

• Compressor Components – Blades, Vanes, Casings, Rotors,
• Combustion Components – Pilot Burners, Fuel Swirlers, Nozzles, Combustion Cans, Combustion Liners, Pins, Bushings
• Turbine Components – Disks, Blades, Vanes, Casings, Wheels

Applicable Coating Technologies – Castolin Eutectic workshop in Newcastle applies a range of coating technologies for the extension of component lifetime:

• Abradable Coatings – AlSi-PE, AlSi-hBN, AlSi-Graphite, Ni-Graphite, NiCrFe-hBN, MCrAlY-hBN-PE, MCrAl-Bentonite, YSZ-PE, DySZ-PE
• Corrosion Resistant Coatings – MoniPlex®, NiAl, MCrAlY
• Slurry & Diffusion Coatings – Al Diffusion
• Thermal Barrier Coatings – AlTi, NiAl, MCrAlY, ZrO2 XY2O3, Al2O3, 3Al2O32SiO2 (Mullite)
• Wear Resistant Coatings – Cr2C3-NiCr, WC-Co, WC-CoCr, Al2O3, Al2O3-TiO2, Cr2O3, NiCrBSi, CoCrW
• Other materials available upon request

Abradable coatings are specially formulated for clearance control applications in gas turbines. By allowing the tips of rotor blades or labyrinth seals to machine a path in the relatively soft but erosion resistant coating deposited in this case, housing or shroud, a close tolerance seal is produced.

The coating applied to the seal rings shown opposite is a plasma sprayed Aluminum-graphite composite for use at 315°-425°C

Thermal barrier coatings (TBC's) are widely used in the hot sections of gas turbines to enhance the life of combustors, vaporisers, nozzle guide vanes, etc which are exposed to high temperature oxication and sulphication attack. 
 

TBC's are normally applied to the platform surfaces of nozzle guide vanes as shown here and a typical coating specification would be an MCrAIY bond coat deposited by Low Pressure Plasma Spraying (LPPS) and a top coat of zirconia partially stabilised with yttria deposited in air by Robotic Plasma Spraying.

MCrAIY coatings are also specified for high temperature clearance control applications in gas turbines.

The coating is applied to the static components, usually liners or shroud segments as shown here and the turbine rotor blades are allowed to cut a path into the rub tolerant coating, which plastically deforms at engine operating temperatures to form a close tolerance seal.