Solid Transfer of Large Particles by Dipping in a Heterogeneous Mixture

Abstract

Solid transfer technology from mixtures is gaining ever-increasing attention from both materials scientists and production engineers due to their high potential in near net shape production of cost-effective engineering components. Dip coating, a wet deposition method is an effective and straightforward way of thin-film/layers formation. It is extensively used as a coating method due to its simplicity, low cost, and reasonable control over the thickness. The dipping mixture can be homogeneous, composite, hybrid, or heterogeneous. The mixtures are often embedded with inorganic fillers, nanoparticles, or clusters (d < 30 nm) that produce a thin film ranging from nm to couple microns. An increase in the volume of solid transfer by the dipping process can open-up a novel technique for the 3D near-net-shape production process via sintering, robocasting or additive manufacturing, and material joining. Adding larger inorganic particle size (> 1μm) and/or by adding higher solid fraction will increase the solid transfer but may result in a multi-phase heterogeneous mixture or slurry. In this work, the physical mechanism of an increased volume of solid transfer with a larger particle size (> 5 μm) is investigated. The metallic particles are spherical in shape with an average diameter of 5.69 μm is considered as the coating material. Polymer-based glue and evaporating solvent are mixed to construct the liquid carrier system (LCS) for large inorganic hard particles. Moderate volume fraction (VF) of inorganic particles (20% < ϕp < 50%) are added into the LCS solution as solid loading. Cylindrical AISI 304 steel wire with dia 0.81 mm is used as the substrate for dipping and coating. The coating thickness (CT) and the surface packing coverage by the particles are measured in our lab. The results presented the influence of volume fraction of inorganic particle and glue composition on the solid transfer from the heterogeneous mixture.