Coating Process Regimes in Particulate Film Production by Forced-Convection-Assisted Drag-Out
Coating Process Regimes in Particulate Film Production by Forced-Convection-Assisted Drag-Out
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DOI：
10.1021/la202040x
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发表时间：
2011-09-20
期刊：
影响因子：
3.9
通讯作者：
Tsapatsis, Michael
中科院分区：
文献类型：
--
作者：
Brewer, Damien D.;Shibuta, Takumi;Tsapatsis, Michael
单层和双层颗粒涂层从水性20 nm直径的二氧化硅分散体的沉积的操作条件被确定在强制对流辅助下的拖出操作的上下文中。在由毛细管数和二氧化硅分散体重量分数参数化的操作窗口内评估干膜厚度、均匀性和形态。三个膜沉积制度相对于毛细管数观察：对流膜沉积在低工艺速率，膜夹带在中等工艺速率，和薄膜过渡制度在中间工艺速率。局部有序的颗粒膜的可变分层厚度，包括（i）不连续的亚单层或（ii）混合的亚单层和单层，（iii）混合的单层和双层，和（iv）多层，是占主导地位的对流沉积条件下。一个地图的形态内的毛细管数的重量分数的操作窗口，其中单层和混合的单层-双层膜被证明在薄膜过渡制度在一个中间的分散体的重量分数。通过拖出110 nm二氧化硅分散体形成的形态的互补图揭示了这种类型的可操作性图的更广泛的适用性。这些操作图是使用模型二氧化硅分散体构建的，因此与其他无机材料的颗粒涂层相关。
Operating conditions for the deposition of monolayer and bilayer particulate coatings from aqueous 20-nm-diameter silica dispersions are identified in the context of a drag-out operation assisted by forced convection. The dry film thickness, uniformity, and morphology are assessed within an operating window parametrized by the capillary number and silica dispersion weight fraction. Three film deposition regimes with respect to the capillary number are observed: convective film deposition at low process rates, film entrainment at moderate process rates, and a thin-film transition regime at intermediate process rates. Locally ordered particulate films of variable layering thickness, including (i) a discontinuous submonolayer or (ii) a mixed submonolayer and monolayer, (iii) a mixed monolayer and bilayer, and (iv) multilayers, are dominant under convective deposition conditions. A map of morphologies is presented within the capillary number weight fraction operating window, where monolayer and mixed monolayer-bilayer films are demonstrated in the thin-film transition regime at an intermediate dispersion weight fraction. A complementary map of the morphologies formed by the drag-out of 110 nm silica dispersions reveals a broader applicability to this type of operability diagram. These operating maps are constructed using model silica dispersions and are therefore relevant to particulate coatings of other inorganic materials.