Drying mechanisms and stress development in aqueous alumina tape casting

Avoiding “mud” cracks during drying of thin films from aqueous colloidal suspensions

“…Following is a brief summary of the three stages of the drying process as described by many investigators [1][2][3][4][5][6]. Initially a constant drying rate stage occurs in which consolidation of the particles in the suspension and evaporation take place at the same constant rate.…”

“…The constraint of the drying thin film by the substrate results in bi-axial tensile stresses at the surface of the drying substrate. It is known that a peak stress occurs at the end of the constant rate drying period and this is when cracking will occur if it is energetically favorable [1,3,4,8]. In the case of rigid particles, the film recovers a nearly stress-free state [3,5] once all the liquid has evaporated from the porous body.…”

“…It has been established that cracking often initiates at the end of the constant rate evaporation stage and typically coincides with a peak in stress [1,3,4]. In recent work, Kiennemann and co-workers [4] measured the evolution with time of Young's modulus of drying aqueous alumina suspensions with ultrasounds using a pulse-echo method in "long-bar mode."…”

“…In recent work, Kiennemann and co-workers [4] measured the evolution with time of Young's modulus of drying aqueous alumina suspensions with ultrasounds using a pulse-echo method in "long-bar mode." Their results show a negligible Young's modulus when the stress peak occurs and thus, the lack of stiffness results in a predisposition to cracking.…”

Preparation of the Pb(Mg1/3Nb2/3)O3 films by aqueous tape casting

“…Additionally, par- ticle rearrangement may bring some stress in the thickness direction. 13,[29][30][31] Surface profilometry analysis was performed in order to investigate the roughness of the dried PMN films through the entire film length. Fig.…”