| dc.description.abstract | This thesis describes the preparation and continuous printing of zirconia ink under different
conditions, as well as the development of silver inks, for the same purpose.
The dispersion of sub-micrometer zirconia powder in industrial methylated spirit using other
additives such as dispersant and binder was investigated with different mixing methods and
at varying powder and binder contents. The use of high shear mixing by triple roll milling
followed by ultrasonic disruption as well as adequate sedimentation and filtration produced a
homogeneous and stable ink of 2.5 vol. % ZrO2. The ink could be printed directly and
continuously on a commercial jet printer without interruption of any kind and the phenomena
occurring during printing were investigated. The optimum modulation frequency for
printing was determined with the generation of pear-shaped and symmetrical droplets.
Printing was made on substrates of surface free energies lower and higher than the surface
tension of the Zr02 ink. Powder migration was observed within a relic of the printed dot on
the second type of substrate. Layers were also overprinted on the second type of substrate
by varying the following: print resolution, printing interval, print area, drying conditions and
ink powder loading. These series of prints were accompanied by the appearance of ridges,
spattering and non-vertical walls and the effects were investigated.
The wettability and shrinkage of droplets of the ceramic ink was also studied in-situ by
monitoring the evolution of contact angle, width of ink-substrate interface and droplet height
with a video camera. The shape of the droplet experienced different dynamics on different
types of substrate.
Lastly, the sedimentation behaviour of ethanol-based silver inks dispersed with different
types of dispersant was investigated with respect to the sediment volume and half-value
time. Deflocculated ink was obtained at a low dispersant level and powder loading. | en_US |
