Characterisation of barium titanate-silver composites, part I: Microstructure and mechanical properties

The paper presents an investigation of the influence of silver particles on the microstructure and mechanical properties of barium titanate. Barium titanate-silver composites have been prepared by ball milling precursor powder constituents; followed by drying, sieving and calcination prior to powder compaction. After sintering the green compacts, microstructural analysis was undertaken involving measurement of grain size, silver particle size, phase composition and phase content. Characterisation of mechanical strength, toughness, hardness and stiffness was also undertaken. Reaction product phases between silver and barium titanate could not be detected. The dispersed silver particles were shown to inhibit densification. Silver particles below 1 μm in size were intragranular and attached to domains. The size of the intergranular silver particles increased with silver content. An increase in silver content improved whereas strength, hardness and stiffness decreased, while toughness was unchanged.