Compiled furnace cyclic lives of EB-PVD thermal barrier coatings

Furnace cycling has been widely used to study the failure of EB-PVD thermal barrier coatings. This contribution compiles TBC furnace cyclic lives over a broad literature base to highlight optimum systems and generalized trends not always apparent in one study. Systems included typical bond coats (Pt-modified aluminides, diffused Pt-only gamma/gamma', and NiCoCrAlY (+/- Pt, Hf) overlays) and superalloy substrates (1st, 2nd, 3rd generation single crystals, directionally solidified, or conventionally cast). Pretreatments included controlled low p(O-2) bond coat pre-oxidation and grit blasting (or none). The aggregate lives (similar to 70) suggest a general trend with temperature, similar to 10-fold decrease for every 100 degrees C increase. Measured alumina scale thicknesses (similar to 30) were, on average, similar to 6.1 +/- 1.8 mu m at failure and independent of temperature for conventional systems. Most failures thus occurred in less time than that predicted to grow 7 mu m of alumina scale (as estimated from separate TGA studies of a Pt-modified aluminide coated 2nd generation single crystal superalloy). A tentative activation energy indicated from the broad distribution of failure times was similar to 280 kJ/mol, while that from homogeneous TGA testing was similar to 380 kJ/mol, with regression coefficients of r(2) = 0.57 and 0.98, respectively. Published by Elsevier B.V.