Transport characteristics of ceramic particles during compaction

Transport characteristics during the compaction containing powders of ceram ic 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 relat ed 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 t o the particular fractions obtained by sieving spray dried powder. The diff usion of small, medium and large particles through three two-fraction syste ms, prepared by combining the initial fractions, was also investigated. The goal was to find a correlation between the particle size distribution of t he powder and the transport characteristics of its particles. The results o btained by powder compacting were used as a basis for calculating the trans port characteristics. The powder was compressed using the double action sta ndard method, and compression curves were generated. The applied pressure r eached maximum at 25 MPa. Also, the mass conductivities were correlated wit h the compression strength of the green samples.