Influence of electrostatic particle interactions on the properties of particulate coatings of titanium dioxide

• Titania nanoparticles were dispersed in ethanol via stirred media milling.
• Coatings on stainless steel were made of these suspension by dip coating.
• The influence of the particle interactions on the coating structure was investigated.
• Coating properties are affected by the structures on micro-, meso- or macroscopic scale.
• The properties were related to the structure (process–structure–property-relation).

HypothesisParticulate coatings are used in a wide range of technical applications. The application affecting properties of these coatings depend strongly on the structure formation along the production process. Thus, primary and secondary particle size, size distribution, particle morphology as well as the particle–particle and particle–fluid interactions of the used formulation affect the resulting coating properties.ExperimentsIn this investigation titanium dioxide particles were dispersed in ethanol with a stirred media mill and stabilised electrostatically. Subsequently, the suspension was destabilised to reach specific pH* values and processed into coatings by dip coating. The influence of the pH∗ value of the suspension on the suspension’s properties such as viscosity, agglomerate size and zeta potential and on its application properties such as coating thickness, micro-mechanical properties, abrasion resistance, gloss, roughness and adhesion was examined.FindingsThe electrostatic particle interactions show a significant influence on the structure formation as well as on the properties of nanoparticulate coatings. The coating properties are affected by the coating structures on micro-, meso- or macroscopic scale. Selective coating properties were related to the coating structure using the theoretical model of Rumpf. Besides other important process and formulation parameters, for the production of homogeneous, functional coatings with the desired properties a precise adjustment of the particle interactions is necessary.

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