Experimental and Numerical Investigation of Environmental Barrier Coated Ceramic Matrix Composite Turbine Airfoil Erosion

Abstract

Ceramic matrix composite (CMC) have higher temperature durability and lower density property compared to nickel-based super-alloys which so far have been widely applied to hot section components of aero-engines/gas turbines. One of promising CMC systems, SiC–SiC CMC is able to sustain its mechanical property at higher temperature, though it inherently needs environmental barrier coating (EBC) to avoid oxidation. There are several requirements for EBC. One of such critical requirements is its resistance to particle erosion, whereas this subject has not been well investigated in the past. The present work presents the results of a combined experimental and numerical research to evaluate the erosion characteristics of CMC + EBC material developed by IHI. First, experiments were carried out in an erosion test facility using 50 μm diameter silica as erosion media under typical engine conditions with velocity of 225 m/s, temperature of 1311 K, and impingement angles of 30, 60, and 80 deg. The data displayed brittle erosion mode in that the erosion rate increased with impact angles. Also, it was verified that a typical erosion model, Neilson–Gilchrist model, can reproduce the experimental behavior fairly well if its model constants were properly determined. The numerical method solving particle-laden flow was then applied with the tuned erosion model to compute three dimensional flow field, particle trajectories, and erosion profile around a generic turbine airfoil to assess the erosion characteristics of the proposed CMC + EBC material when applied to airfoil. The trajectories indicated that the particles primarily impacted the airfoil leading edge and the pressure surface. Surface erosion patterns were predicted based on the calculated trajectories and the experimentally based erosion characteristics.

Solid particle erosion in ceramic matrix composites and environmental barrier coatings: A perspective

“…9,[12][13][14][15][16][17][18][19][20][21][22] However, until recently, little work has been performed on characterizing and understanding the SPE behavior of CMCs and EBCs. [1][2][23][24][25][26] Conversely, extensive work has been performed on superalloys and TBCs. [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] In fact, SPE of superalloys and TBCs remains an area of active research.…”

“…Fourteen years passed between the work of Singh et al 51 in 2005 and the next study on SPE of EBCs reported by Okita et al 25 in 2019. Okita et al 25 investigated the SPE behavior of an APS EBC with a Si bond coat deposited on a CMC.…”

“…Fourteen years passed between the work of Singh et al 51 in 2005 and the next study on SPE of EBCs reported by Okita et al 25 in 2019. Okita et al 25 investigated the SPE behavior of an APS EBC with a Si bond coat deposited on a CMC. The exact composition of the EBC was not reported although it was noted that the EBC was an oxide with good chemical stability and low reactivity.…”

“…Expanding upon the work by Singh et al 51 and Okita et al, 25 The data from Singh et al 51 and Okita et al 25 are included for comparison. The PS-PVD coating exhibited a power law dependence with respect to particle kinetic energy as given by Equation 4where γ = 1.3 × 10 −6 and b = 1.26.…”

“…In addition, it is observed in Figure 11(A) that the three EBC studies show reasonable agreement on the basis of a mass loss erosion rate (mg/impact) with respect to particle kinetic energy despite some differences in test parameters. While a volumetric erosion rate would be more ideal to compare the different EBCs, the densities of the BSAS EBC investigated by Singh et al 51 and the EBC investigated by Okita et al 25 were not reported. Similarly, as shown in Figure 11(B), the EBCs from the three studies follow a similar functional dependence with respect to impingement angle.…”