title: High solids loading ceramic colloidal dispersions in UV curable media via comb-polyelectrolyte surfactants.
abstract: Ceramic articles and ceramic/polymer composites with complex 3d shapes can be produced by rapid prototyping techniques such as stereolithography of ceramic dispersions in UV curable resins. Nanometer and submicrometer ceramic particles are advantageous for high resolution microstructures, surface quality and reduced sintering temperatures. Frequently, special surfactants are needed to maximize solids loading while maintaining suitable rheological properties for stereolithography applications (viscosity <5 Pa s, 301/s). We present here a general scheme for relatively high loading/low viscosity dispersions of nanometer and submicrometer particles in UV curable resins using comb-polyelectrolyte surfactants. In the present approach, adsorption is favorably carried out in aqueous media and the dry particles with adsorbed surfactant are transferred to the organic media through centrifugation, washing, drying and dry milling. The method is demonstrated for Al(2)O(3), ZnO and mixed Al(2)O(3)/ZnO colloidal dispersions. Dispersions containing >48 vol% particles suitable for stereolithography have been achieved. Dispersions containing 36 vol% particles are predicted to have viscosities in the range suitable for direct inkjet printing applications at 75 degrees C. The particle stabilization and transfer schemes, rheological behavior and UV curing characteristics are presented.
authors.affiliation: Empa, Swiss Federal Laboratories for Materials Testing and Research, Laboratory for High Performance Ceramics, Uberlandstrasse 129, CH-8600 Dübendorf, Switzerland. yoram.dehazan@empa.ch
authors.forename: Yoram
authors.initials: Y
authors.lastname: De Hazan
authors.forename: Judit
authors.initials: J
authors.lastname: Heinecke
authors.forename: Alfred
authors.initials: A
authors.lastname: Weber
authors.forename: Thomas
authors.initials: T
authors.lastname: Graule