Rheological characterisation of water-based AlN slurries for the tape casting process

In the present work rheological properties of aqueous concentrated AlN suspensions have been investigated in the presence of a sintering aid, deffloculant, binder and plasticizers, in order to screen the most suitable experimental conditions to obtain a good rheological behaviour for tape casting thick and non-cracked tapes with good flexibility. Suspensions exhibiting the desired shear thinning behaviour could be prepared. Adding binder and plasticizers did not change the shear thinning behaviour, but the viscosity revealed an increasing trend with increasing added amounts of binder. The flexibility was improved for the tapes derived from the more viscous suspensions containing higher amounts of binder. Crack free tapes having a maximum thickness of 1.5 mm, and with binder and plasticizer contents in the ranges of 10–15 wt.% and 5–10 wt.%, respectively, could be obtained.