Microstructures and mechanical properties of dense particle gels: Microstructural characterisation

The macroscopic mechanical properties of wet ceramic green bodies and densely packed coagulated colloidal particle gels strongly depend on the local arrangement of the powder particles on length scales of a few particle diameters. Heterogeneous microstructures exhibit up to one order of magnitude higher elastic properties and yield strengths than their homogeneous counterparts. The microstructures of these gels are analysed by the "straight path" method quantifying quasi-linear arrangements of particles. They show similar characteristics than force chains bearing the mechanical load in granular material. Applying this concept to gels revealed that heterogeneous colloidal microstructures show a significantly higher straight path density and exhibit longer straight paths than their homogeneous counterparts.