Thermal analysis of partially stabilized zirconia and lanthanum magnesium hexaaluminate as thermal barrier coatings over hastelloy X gas turbine blade

Abstract EN

The sprayed partially stabilized zirconia (8 % by wt.

yttria) and lanthanum magnesium hexaaluminate were investigated as materials for thermal barrier coatings over Hastelloy X as substrate for a high temperature gas turbine blade model using NiCrAlY as an interlayer bond coat material.

The temperature and heat flux based steady and transient thermal analyses were performed over variable thickness models for two different coating materials using a FEM based commercial ANSYS Workbench v14.5 software package.

It was found that under applied thermal loading conditions, just a 200 microns thick zirconia coating used with 150 microns NiCrAlY layer was capable to reduce steady state substrate temperatures by 35.6 % and proved to be 3.72 % more effective than an equal thickness lanthanum magnesium hexaaluminate coating.

Similarly, steady state top surface heat flux was found to be 15.7 % lesser for the former as compared to later.

The increased thickness of coatings observed further reductions in the substrate temperatures and top surface heat flux values, however, the zirconia coatings were found to be more effective than lanthanum aluminate coatings at higher thicknesses in terms of suppressions of heat penetration and substrate temperatures.

A steady state top coat – bond coat interface heat flux analysis further helped in anticipating that thin films of zirconia could be more durable than lanthanum aluminate coatings in the high flux working conditions as prevailing inside a gas turbine system.