Thermal conductivity of zirconia coatings with zig-zag pore microstructures

Highly porous zirconia based thermal barrier coatings have recently been sy nthesised with zigzag morphology pores which appear to impede heat flow thr ough the thickness of the coating. A combined analytical/numerical study of heat conduction across these microstructures is presented and compared wit h thermal conductivity measurements. The effects of pore volume fraction, p ore type, pore orientation and pore spacing, to-ether with the wave length and the amplitude of zig-zag pore microstructures on overall thermal perfor mance are quantified. The results indicate that even a few volume percent o f zig-zag inter-column pores oriented normal to the substrate surface reduc e the overall thermal conductivity of the coatings by more than 50%. (C) 20 01 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reser ved.