The rheological characterization of concentrated suspensions is complicated by the heterogeneous nature of their flow. In this contribution, the shear viscosity and wall slip velocity are quantified for highly concentrated suspensions (solid volume fractions of 0.55–0.60, D_4,3 ~ 5 µm). The shear viscosity was determined using a high-pressure capillary rheometer equipped with a 3D-printed die that has a grooved surface of the internal flow channel. The wall slip velocity was then calculated from the difference between the apparent shear rates through a rough and smooth die, at identical wall shear stress. The influence of liquid phase rheology on the wall slip velocity was investigated by using different thickeners, resulting in different degrees of shear rate dependency, i.e. the flow indices varied between 0.20 and 1.00. The wall slip velocity scaled with the flow index of the liquid phase at a solid volume fraction of 0.60 and showed increasingly large deviations with decreasing solid volume fraction. It is hypothesized that these deviations are related to shear-induced migration of solids and macromolecules due to the large shear stress and shear rate gradients.

浓缩悬浮液的流变特性因其流动的异质性而变得复杂。在这个贡献中，剪切粘度和壁面滑移速度被量化为高浓度悬浮液（固体体积分数为 0.55-0.60，D _4,3 ~ 5 µm)。使用配备有 3D 打印模具的高压毛细管流变仪测定剪切粘度，该模具具有内部流动通道的凹槽表面。然后根据在相同壁剪切应力下通过粗糙和光滑模具的表观剪切速率之间的差异计算壁滑动速度。通过使用不同的增稠剂研究了液相流变对壁滑移速度的影响，导致不同程度的剪切速率依赖性，即流动指数在 0.20 和 1.00 之间变化。在固体体积分数为 0.60 时，壁面滑移速度与液相的流动指数成比例，并且随着固体体积分数的降低显示出越来越大的偏差。