A novel fully nano-equiaxed-structured thermal insulation Y2O3-stabilised ZrO2 (YSZ) coating was first successfully deposited using very-low-pressure plasma spray (VLPPS) and the agglomerates feedstock from nanometer-sized powders. The microstructure of fully nano-equiaxed-structured coating is different from that of a “bimodal microstructure”, which is currently the dominant nanostructured coating. This desirable structure in the new TBCs appears to be responsible for their improved thermal cycling lifetimes and reduced thermal conductivity relative to those of conventional plasma-sprayed TBCs with lamellar structures or bimodal structures. Preliminary results from experiments aimed at understanding the VLPPS deposition mechanisms suggest that the nanometre-scale equiaxed in the coating are formed from original nano-particles, they underwent melted in the low pressure plasma plume and solidification onto the substrate. The VLPPS method, which offers some unique advantages over the conventional plasma-spray process, is generic in nature and can be potentially used to deposit a wide variety of ceramic coatings for diverse applications.

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