Kendra Erk Graduate Student B.S. MSE with Highest Distinction, 2006, Purdue University Cook Hall 2057, 1-7199 k-erk at northwestern dot edu

Thermoreversible Gelcasting of Titanium Components

The process of thermoreversible gelcasting has been demonstrated [1,2] to be effective at producing dense ceramic components from a low-viscosity gel. The foundation of thermoreversible gelcasting is built upon use of an acrylic triblock copolymer with a selectively solvated midblock. Below a critical temperature, physical crosslinking results in the formation of a network polymer gel, able to support the addition of ceramic particles and retain a low viscosity. This fluid suspension is easily poured into molds and cooled below its critical temperature, forming a ceramic greenbody upon solvent evaporation which is then able to be sintered into a near-theoretically dense specimen. Prior to solvent evaporation, the gel can be reheated and recast an infinite amount, thus allowing this process to be reversible.

It is desirable to extend the thermoreversible gelcasting process to form titanium components for biomedical applications. Components such as screws are typically machined from Ti barstock, resulting in significant material waste and increased production costs. Adapting thermoreversible gel casting to the fabrication of Ti screws would allow for reduction in waste as components are cast to net shape and casting is reversible. Through incorporation of additional organics, a porous titanium structure would result with sintering; porosity would decrease the elastic modulus mismatch between Ti and bone as well as allow for bone in growth to stabilize the component.

This material is based upon work supported under a National Science Foundation Graduate Research Fellowship.

[1]  "Thermoreversible Gelcasting: A Novel Ceramic Processing Technique" Montgomery, J.K.; Drzal, P.L.; Shull, K.R.; Faber, K.T., J. Amer. Ceramic Soc., 85, 1164 (2002).
[2]  "Origins of mechanical strength and elasticity in thermally reversible, acrylic triblock copolymer gels" Drzal, P.L.; Shull, K.R., Macromolecules, 36, 2000 (2003).