Transport characteristics of ceramic particles during compaction

Abstract

Transport characteristics during the compaction containing powders of ceramic particles, expressed as mass conductivities derived from quasi-diffusion coefficients, were analyzed. Quasi-diffusion coefficients are obtained by applying the Dalla Valle concept of pressure diffusion as well as the related mathematical model. The model enables the calculation of diffusivity in terms of particle size, compacting pressure and density of the green sample. The analysis was based on investigations of particle diffusion for three representative sizes (d = 0.07, d = 0.13 and d = 0.45 mm). The particles belong to the particular fractions obtained by sieving spray dried powder. The diffusion of small, medium and large particles through three two-fraction systems, prepared by combining the initial fractions, was also investigated. The goal was to find a correlation between the particle size distribution of the powder and the transport characteristics of its particles. The results obtained by powder compacting were used as a basis for calculating the transport characteristics. The powder was compressed using the double action standard method, and compression curves were generated. The applied pressure reached maximum at 25 MPa. Also, the mass conductivities were correlated with the compression strength of the green samples.