Spray freeze drying of nanozirconia powders

Nanozirconia ceramics have great potential to be used in a range of applications from dental implants to petrochemical valves due to their enhanced mechanical properties and superior hydrothermal ageing resistance. Unlike conventional ceramic components that are normally produced in large quantities with low costs using various conventional dry forming or wet forming methods, industry scale processing of nanoceramics has not yet been achieved. Concentration and granulation of nanostructured 3 mol% yttria stabilised zirconia via a spray freeze drying (SFD) technique was investigated to determine whether large scale dry forming of nanoceramics would be possible. Commercial nanosuspension with a primary particle size of 16 nm was concentrated to 55 wt% solids content using an electrosteric dispersant, β-alanine, whilst retaining low viscosities of ~20 mPa s at a 200 s-1 shear rate. The nanosuspensions concentrated using the β-alanine also displayed good ageing resistance and it has been proven that a large scale vacuum assisted rotary evaporator can be used to perform concentration in industry. [Continues.]