01-04-2011, 11:49 AM
Presented By:-
SANJIV KUMAR
SANJIV.pptx (Size: 415.21 KB / Downloads: 132)
WHAT IS TBC?
• Layer of system deposited on metallic component subjected to high temp.
• Increases the mechanical component working life.
• Increases process efficiency.
HISTORICAL BACKGROUND
Pratt & Whitney first introduced TBC on burner can in JT8D engine in 1963
This TBC consisted of zirconia stabilized by addition of 22%wt MgO
To avoid high temperature phase to low temperature phase transformation
In current system ceramic consists of 7wt% yttria partially stabilized zirconia(7YSZ)
DIFFERENT LAYERS
Four layers
Ceramic top coat
Thermally grown oxide(TGO)
Bond coat
Substrate
Ceramic top coat
Top most layer
Provides thermal insulation
Low thermal conductivity (2.3 W/m*k) at temp of thousand *C
Made of Y2O3 stabilized with ZrO2 or YSZ
YSZ has high mp(2700*C)
Elastic modulus of 50GPa
Strain tolerant
Bond coat:
Metallic layer
75-150 micrometer thick
Made of Ni & Pt
Function:
Protect basic material against oxidation corrosion
(on one side)
Provide good adhesion to the thermal insulating layer
(on other side)
Thermally Grown Oxide(TGO):
TGO formed when ceramic top coat reacts with bond coat in very high temperature
Formation growth is slow, uniform & defect free
1-10 micrometer thick
Substrate:
Usually Ni or Co based super alloy
High temperature strength
Ductility and oxidation resistance
Deposition Processes
Bond coat is deposited by chemical vapor deposition
HVOF technology is also used for bond coat deposition
Ceramic top coat is deposited into two ways
Air plasma spray (APS) &
Electron Beam Physical vapour deposition (PVD)
Air Plasma Spray:
Ceramic powder is fed into a plasma torch and sprayed molten on the surface of metallic substrate
Droplets of molten material form splats on the metallic substrate
In APS top coat the orientation of the cracks and pores are normal to flow of heat which reduces thermal conductivity from 2.3 W/mo k to 0.8- 1.7 W/m0 k
EB PVD METHOD:
High quality castings
A material source of the coating material is vaporized with an electron beam and vapor uniformly condenses on the surface of the turbine blade
SANJIV KUMAR
SANJIV.pptx (Size: 415.21 KB / Downloads: 132)
WHAT IS TBC?
• Layer of system deposited on metallic component subjected to high temp.
• Increases the mechanical component working life.
• Increases process efficiency.
HISTORICAL BACKGROUND
Pratt & Whitney first introduced TBC on burner can in JT8D engine in 1963
This TBC consisted of zirconia stabilized by addition of 22%wt MgO
To avoid high temperature phase to low temperature phase transformation
In current system ceramic consists of 7wt% yttria partially stabilized zirconia(7YSZ)
DIFFERENT LAYERS
Four layers
Ceramic top coat
Thermally grown oxide(TGO)
Bond coat
Substrate
Ceramic top coat
Top most layer
Provides thermal insulation
Low thermal conductivity (2.3 W/m*k) at temp of thousand *C
Made of Y2O3 stabilized with ZrO2 or YSZ
YSZ has high mp(2700*C)
Elastic modulus of 50GPa
Strain tolerant
Bond coat:
Metallic layer
75-150 micrometer thick
Made of Ni & Pt
Function:
Protect basic material against oxidation corrosion
(on one side)
Provide good adhesion to the thermal insulating layer
(on other side)
Thermally Grown Oxide(TGO):
TGO formed when ceramic top coat reacts with bond coat in very high temperature
Formation growth is slow, uniform & defect free
1-10 micrometer thick
Substrate:
Usually Ni or Co based super alloy
High temperature strength
Ductility and oxidation resistance
Deposition Processes
Bond coat is deposited by chemical vapor deposition
HVOF technology is also used for bond coat deposition
Ceramic top coat is deposited into two ways
Air plasma spray (APS) &
Electron Beam Physical vapour deposition (PVD)
Air Plasma Spray:
Ceramic powder is fed into a plasma torch and sprayed molten on the surface of metallic substrate
Droplets of molten material form splats on the metallic substrate
In APS top coat the orientation of the cracks and pores are normal to flow of heat which reduces thermal conductivity from 2.3 W/mo k to 0.8- 1.7 W/m0 k
EB PVD METHOD:
High quality castings
A material source of the coating material is vaporized with an electron beam and vapor uniformly condenses on the surface of the turbine blade