High temperature behavior of monodisperse porosity in alumina films

Understanding the sintering behavior of tailored porosity in thin-film ceramics is essential for applications in photonics, thermal coatings, catalysis, and electrodes. Alumina films exhibiting a random distribution of templated pores with monodisperse size were produced by spin coating from suspensions of alumina powder and polystyrene microspheres. The microstructural evolution, grain size, pore size, and their respective distributions were determined as a function of the initial volume fraction of templated pores, sintering temperature, and time. The behavior between grains and pores at the surface and in the bulk was evaluated and compared to other disordered and ordered porous alumina systems. Above a pore fraction threshold of ∼9 vol%, increasing pore fractions retarded grain growth, with smaller grains observed between close pores. While the average bulk pore size did not change with sintering temperature, time, or pore fraction, it did produce a broader pore size distribution with different pore geometries.