Composite and Functionally Gradient Parts

Functionally Gradient parts with Local Composition Control

A unique capability of the 3D Printing process is the ability to locally tailor the material composition of a part. This is made possible by precise control of a multiple-material printhead (see figure below). An appropriate data structure is all that is required to generate parts with multiple materials. This allows the part designer to locally tailor properties such as strength, toughness, or heat transfer, for example. Any material gradient can be imposed over any region, and locally, half-toning algorithms can be applied.

Macroscopically Toughened Composite (MTC) Parts

It has been shown that silicon carbide reinforced aluminum alloys can display higher Charpy impact values if the SiC particulates are clustered into well organized arrays of "macro fibers" as compared to uniformly dispersed particulate reinforced composites. This concept has been demonstrated with 3-D printed preforms at MIT. Since these pseudo fibers can be printed into any array and can be infiltrated by techniques developed at MIT, a more flexible and low cost approach to the manufacture of MTC components is now possible.

The part shown to the left was produced as follows. Here, the pseudo-fibers are supported by densely printed end blocks. The printed preform is removed from the powder bed after heating to set the binder. It is then inserted into a die and pressure-infiltrated with molten metal. After removal from the die, a net-shaped component is produced with little need for additional machining. The concept of macroscopically toughened composites has many possibilities:

  • enhanced material properties including:

    • toughness

    • wear

    • thermal or electrical conductivity

    • thermal expansivity

  • ability to locally vary toughness or wear properties

Direct Casting of Metal Matrix Composite Components by 3DPTM

The concept of creating ceramic shells by Three Dimensional Printing can be extended to the fabrication of ceramic performs, which are used to create metal matric composite parts by pressure infiltration of a molten metal.

Silicon carbide preforms for aluminum infiltration

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This web site is maintained by Julie Baars Kaczynski
Last updated on Wednesday, June 28, 2000