Method: A laboratory investigation into the production of a ceramic/polymer composite material was carried out using the technique of freeze casting followed by characterization using mechanical test methods, including compressive strength and abrasion testing.
Result: Processing using the technique of freeze casting has enabled the production of anisotropic porous samples depending upon the volume of solid loading. A ceramic slurry is created using alumina powder mixed with deionised water with the addition of dispersant and binder. It has been possible to make a variety of samples with different percentages of solid loading; these include 10%, 20%, 30% and 40% alumina powder. The samples were then freeze cast along a temperature gradient -10 to 1C producing a unidirectional lamellar sample through the formation of ice crystals. Following drying of the samples in a freeze drier to produce a unidirectional porous structure; it was possible to infiltrate these preforms, after sintering, with a second material such as an epoxy resin producing a composite material. The preliminary results show the composites have good mechanical and wear properties. In addition further samples have been made incorporating treatment of the porous ceramic preform with a silane coupling agent to improve the mechanical properties.
Conclusion: Fabrication of a new composite material has excellent potential for the future use as an aesthetic orthodontic bracket material. It can be produced using a cheap, easy and environmentally friendly method.