Dense and porous zirconia prepared by gelatine and agar gel-casting: Microstructural and mechanical characterization

Dense and cellular yttria-tetragonal zirconia polycrystal (Y-TZP) bodies were produced by using a natural gelatine and two different agars as gelling agents, while commercial polyethylene (PE) spheres were added (125 to 300 μm diameter) as a volatile pore forming agent to create 50-65 vol% spherical macro-pores, uniformly distributed in a micro-porous matrix. The microstructure of all dense and cellular ceramics was characterized by FEG-SEM and Focused Ion Beam (FIB) techniques. The mechanical properties of both dense and porous samples were investigated at the microscale by nanoindentation testing, while the influence of microporosity was obtained by the analysis of hardness and modulus depth profiles, coupled with FIB-SEM section observations of selected indentation marks. Mechanical characterization at the macroscale consisted of uniaxial compression tests and four point bending tests.