Coating thin liquid films with complex rheological behaviour on permeable substrates is often an important requirement in several applications such as contact lenses, textiles, and paper-based electronics. Here, we extend the classical Landau-Levich problem of dip coating of Newtonian liquids on rigid substrates to liquids of power-law rheology on permeable substrates. Our results suggest distinct deviation from the classical Landau-Levich relation through exhibition of different regimes of varying dependence of coating film thickness on withdrawal speed. A process map is presented depicting these coating thickness regimes for a wide range of operating parameters such as the substrate permeability factor, power-law exponent of the liquid, and a rescaled capillary number.

在可渗透基材上涂覆具有复杂流变行为的液体薄膜通常是一些应用的重要要求，例如隐形眼镜，纺织品和基于纸张的电子产品。在这里，我们将牛顿液体在刚性基材上的浸涂的经典Landau-Levich问题扩展到渗透性基材上的幂律流变学液体。我们的结果表明，通过展示不同的涂膜厚度对拉丝速度的依赖性的不同机制，与经典的Landau-Levich关系存在明显的偏离。给出了一个工艺图，描述了各种操作参数（例如基材的渗透率，液体的幂律指数和重新定标的毛细管数）的这些涂层厚度方案。