Published online by Cambridge University Press: 10 February 2011
Freeform fabrication methods build materials by the repetitive addition of thin layers. This approach can be applied to build parts from epoxy resin which is modified with a gelling agent to solidify the material until curing occurs. High strength and stiffness parts can be obtained through fiber reinforcement but the fiber content is limited by packing effects. We have found that a combination of two types of fibers can be used to achieve higher strength and stiffness than can be obtained from a single fiber type.
An alternative route to reinforcement is to form the reinforcing phase after the material is deposited by an in situ reaction. This approach has been applied to the use of freeform fabrication to make bars of mineralized gel and of methacrylate-silica hybrids. Good mechanical properties can be attained in each case, with up to 50 vol.% inorganic phase and bend strengths in the range from 50-100 MPa.