Degradation of Protective Coatings of Turbine Blades during Exploitation.

Degradation of Protective Coatings of Turbine Blades during Exploitation.

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Diffusion Al-Si coatings are used to protect rotor blades of the aircraft engine DV2 produced by HTC-AED a.s. Považská Bystrica, Slovakia, against high-temperature corrosion in environments containing sulphur compounds. The time-temperature area beyond a critical temperature of the outgoing gas is used as an empirical exploitation parameter D indicating a degradation level. The efficiency of such approach was investigated by analyzing the surface layers of high-pressure rotor blades after exploitation corresponding to different values of D. Simple relationships between the relative width of remaining layer and the parameter D for both the back and the trough of the blade were established. The relations indicate that the relative widths of remaining layers, corresponding to the upper limit Du = 1.5.10^9 K4.s2 (already requiring repair), correspond to 60 % for the back of the blade and 32 % for the trough. Thus, the relations yield a clear geometrical interpretation of the empirical parameter D. However, the methodology fails to provide reasonable information in a special case of the gas burning outside the combustion chamber due to a sudden decrease of turbine revolutions.

Diffusion Al-Si coatings are used to protect rotor blades of the aircraft engine DV2 produced by HTC-AED a.s. Považská Bystrica, Slovakia, against high-temperature corrosion in environments containing sulphur compounds. The time-temperature area beyond a critical temperature of the outgoing gas is used as an empirical exploitation parameter D indicating a degradation level. The efficiency of such approach was investigated by analyzing the surface layers of high-pressure rotor blades after exploitation corresponding to different values of D. Simple relationships between the relative width of remaining layer and the parameter D for both the back and the trough of the blade were established. The relations indicate that the relative widths of remaining layers, corresponding to the upper limit Du = 1.5.10^9 K4.s2 (already requiring repair), correspond to 60 % for the back of the blade and 32 % for the trough. Thus, the relations yield a clear geometrical interpretation of the empirical parameter D. However, the methodology fails to provide reasonable information in a special case of the gas burning outside the combustion chamber due to a sudden decrease of turbine revolutions.

Degradation, Protective Coatings, Turbine Blades

Degradation, Protective Coatings, Turbine Blades

POKLUDA, J.; KIANICOVÁ, M.; ŠVEJCAR, J.

01.05.2008

0000000000000

Failures 2008

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