Abstract
This paper deals with the mechanisms and kinetics of interactions between screen printed and fired PbO layers and ceramic substrates: alumina and beryllia. The interaction with alumina occurs via two main processes: (i) a reaction between PbO and Al2O3 grains, which induces the formation of a crystalline phase, Pb2Al2O5; and (ii) an interdiffusion process involving Pb and the intergranular amorphous phase in the ceramic substrate. This latter process results in a compositional change of the intergranular phase at considerable depths inside the ceramic substrate, as well as in the formation of a high lead glass layer on the substrate surface. Since PbO is not completely reacted, the Pb penetration in the ceramic is diffusion limited (penetration depth , where td is the reaction time) with an activation energy of 1.20 ± 0.05 eV. The ceramic microstructure significantly affects the interaction processes.
Published Version
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