Preparing of nanostructured Al2O3–TiO2–ZrO2 composite powders and plasma spraying nanostructured composite coating

• Nanostructured Al2O3–TiO2–ZrO2 powders for plasma spraying were prepared by spray drying.
• The as-prepared powders have good sphericity, high density and good flowability.
• The nanostructured coating was prepared by plasma spraying nanostructured powders.
• The nanostructured coating possessed higher hardness and toughness.

Nanostructured Al2O3–TiO2–ZrO2 composite powders for plasma spraying were prepared by spray drying granulation technology. The effects of processing parameters on the microstructure and properties of composite powders were investigated. The results show that with increasing the slurry solid content, the particle size of powders increases, and the bulk density of powders increases, and the flowability of powders increases firstly and then decreases. With increasing the binder content, the particle size of powders increases, and the bulk density of powders increases, and the flowability of powders increases firstly and then decreases. With increasing the spray drying temperature, the particle size of powders increases, and the bulk density and flowability of powders increases firstly and then decreases. The most appropriate spray drying parameters are the slurry solid content of 40 wt.%, the binder content of 2.0 wt.% and the spray drying temperature of 250 °C. The nanostructured composite coating was successfully prepared by using the as-prepared nanostructured Al2O3–TiO2–ZrO2 composite powders as feedstocks. The nanostructured coating possessed higher hardness and toughness compared with the conventional microstructured one, which was attributed to the use of the nanostructured composite powders feedstocks.