Sintering Kinetics of Plasma-Sprayed Zirconia TBCs

Abstract

A model of the sintering exhibited by EB-PVD TBCs, based on the principles of free energy minimization, was recently published by Hutchinson et al [1]. In the current paper, this approach is applied to the sintering of plasma-sprayed TBCs and comparisons are made with experimental results. Predictions of through-thickness shrinkage and changing pore surface area are compared with experimental data obtained by dilatometry and BET analysis respectively. The sensitivity of the predictions to initial pore architecture and material properties are assessed. The model can be used to predict the evolution of the contact area between overlying splats. This is in turn related to the through-thickness thermal conductivity, using a previously-developed analytical model [2].

Heat Transfer Through Plasma-Sprayed Thermal Barrier Coatings in Gas Turbines: A Review of Recent Work

“…The spraying conditions, and coating microstructures, were similar to those reported elsewhere [31,[75][76][77]. The predictions shown were obtained using input data, and predictions from the sintering model, shown in Table I.…”

“…It's also clear that these changes lead to increases in (effective) thermal conductivity (and also in stiffness). Since the sintering model of Cipitria et al [76,77,85] is based on much the same geometrical model as that of Golosnoy et al [15] for prediction of conductivity, and also involves similar microstructural characterisation parameters, it's possible to combine them in order to predict how the conductivity changes during heat treatment. For example, Fig.9 compares such predictions with experimental data from Ratzer-Scheibe et al [73,74], relating to PS YSZ TBCs given short or prolonged heat treatments at 1100˚C.…”

Microstructural dependency of thermal expansion and sintering shrinkage in plasma-sprayed zirconia coatings

“…Recently, Cipitria et al have proposed a numerical analysis model for sintering in free-standing plasma-sprayed coatings [16,17]. Hence, we discussed the relevance between the obtained differences in shrinkage behavior and the microstructure by using this numerical model.…”

“…The quartic Runge-Kutta method was utilized to solve Eq. (3), in which the required material properties for the calculation were referred to Cipitria's report [16].…”

Low‐temperature stiffening of air plasma‐sprayed 7 wt% Y2O3‐stabilized ZrO2

“…They found the surface area of cracks and voids kept decreasing beyond 600°C and almost 33% of surface area of voids and microcracks have been lost from as sprayed coating to 1000°C heat‐treated coating. There are various other studies which have shown the effect of sintering on reduction in porosity content and volume shrinkage …”