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4649 |
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Effect of deposition process of bondcoats in suspension plasma sprayed thermal barrier coatings on lifetime |
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Mohit Gupta* / University West, Sweden Nicolaie Markocsan / University West, Sweden Xin-Hai Li/ Siemens Turbomachinery AB, Sweden Lars Östergren/ GKN Aerospace Engine Systems, Sweden Mitch Dorfman/ Oerlikon Metco, USA |
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Atmospheric Plasma Sprayed (APS) and Electron Beam Physical Vapour Deposition (EB-PVD) thermal barrier coatings (TBCs) are commonly used for thermal protection of components in modern gas turbine application such as power generation and aero engines. It is well known for both APS and EB-PVD TBCs that the process employed for deposition of bondcoat affects the lifetime of TBCs significantly. Conventionally, High Velocity Oxy-Fuel (HVOF) and Vacuum Plasma Sprayed (VPS) bondcoats are used for APS and EB-PVD TBCs respectively in order to achieve high lifetime. However, the effect of bondcoat deposition process in the new TBC systems consisting of Suspension Plasma Sprayed (SPS) topcoats on lifetime has not been studied in detail. The objective of this work was to study the effect of bondcoat deposition process in SPS TBCs and whether the knowledge from APS and EB-PVD systems could be transferred to SPS systems. In this work, HVOF, VPS, High Velocity Air Fuel (HVAF) and Chemical Vapour Deposition (CVD) bondcoats were deposited. The topcoat was deposited by SPS in all cases. Lifetime of these coating systems was examined by thermal cyclic fatigue and thermal shock testing. The failure mechanism in each case was investigated and will be discussed. |