The state-of-the-art ceramic armor consists of a heterogeneous boron carbide () and silicon carbide () ceramic blend. Uniquely, the combination of these two components can exceed the mechanical performance of each component individually. Traditional ceramic forming techniques includes pressing, extrusion, slip casting, tape casting, and injection molding. These methods are limited in their ability to produce complex shapes, as well as control composition. Additive Manufacturing (AM) allows for rapid prototyping for composite ceramics while controlling the composition.Army Research Labs previously modified an off-the-shelf 3D printer to print a ceramic slurry of &nbsp;and . Using additive manufacturing to produce these ceramic meso/microstructures allows researchers to observe the material properties of different ceramic designs through both layering and mixing of different compositions within layers. Initial iterations suggest improvement in mixedness of the ceramic composite is desirable to create a more homogenous blended microstructure.The printer consists of three main components: the print head, the feed system, and the gantry. The ceramic slurries are fed into the print head and then extruded out of the nozzle using an augur to mix and convey the slurry down a barrel and out of the print head. The initial design utilized a basic augur shape designed to move the slurry along, but it did not effectively mix the two slurries while printing.We have recreated this ceramic printer and worked through a series of design modifications on the extrusion system, predominantly the auger, to produce a ceramic print with a more homogenous mixture of input components. We have also modeled the auger in SolidWorks, matching the rheological properties of the ceramic slurries engaged in the print, to determine influence of geometric modifications on auger performance. Experimental augers are printed using a Formlabs 2 stereolithography printer, with clear resin, and are tested on the modified 3D printer. Modeling predictions are verified through the experimental print allowing for rapid analysis of geometric modifications without requiring an experimental print for each iteration. &nbsp;&nbsp;Additionally, previous auger designs focused on shear mixing which is largely attributed to the auger threads. Current designs investigate chaotic mixing, which is achieved by placing short protruding studs in patterns around the auger shaft. The combination of shear and chaotic mixing achieved a more homogeneous mixture over a comparable chamber length.The group examined the homogeneity of the mixture under a 10x and then 40x microscope before advancing to images in a scanning electron microscope. A point counting method similar to traditional volume fraction analysis was employed to evaluate mixedness.

Additive Manufacturing With Ceramics

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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