3D printing ballistic ketchup

When I tell people I work with ceramic materials and processing, the first thing that come to their minds are coffee mugs, or a very romantic scene from the movie Ghost. Although, that is not completely inaccurate, ceramic materials are more popular, and important, that people realize. Your bones and teeth are ceramic. You'll find ceramic components on airplanes, a turbine, or in your car engine. That white thing on the top of the spark plugs for your car, yeah, that is ceramic. Many components that build up your .. Many components that build up your smartphone are ceramic materials, and well… your toilet is ceramic too. Hopefully, you get my point now.

Among the ceramics materials used for many engineering applications, boron carbide offers a really nice combination of properties. It is lighter than aluminum, has a density of 2.52 g/cm3, and after diamond and boron nitride, it is the hardest material in the world. The problem with ceramic material is that we normally process them from a powder form. That means that we need to take a bunch of powder (small little particles) and turn them into a single component. If that process is not properly done, there will be a lot of pores and cracks that will affect the final performance.

To overcome some of the limitations that we currently have when processing ceramic materials such as boron carbide, we developed a new processing method that basically transforms the processing into playing with clay. In order to do that we first need to create a “ballistic ketchup” (more on that later). When we mix ceramics particles with water and the proper polymer, we obtain what is called a non-newtonian fluid; pretty much whatever is not water. As you can guess, ketchup is a non-newtonian.  To reach the properties needed for this processing, we added the right polymer, using the lowest possible concentration, and the most effective molecular weight (remember polymer are like spaghetti, the molecular weight tells you how long the pasta is, short or long). For that, we use polyetheramine (PEI) with a molecular weight of 25000 g/mol and a concentration of approximately 5 Vol%. 

Once we have our suspension it can be cast or interjected. Additionally, ceramics suspensions made of boron carbide can be 3D printed. As you can see in the video, it is possible to stack layers of “ballistic ketchup” on top of each other. We call it ballistic ketchup because once the printing is done and we further process the component at high temperatures, it will have pretty similar properties to the actual materials they use for real armor plates.

If you want to find more about the details and scientific insights of this project, you can read the peer reviewed papers in the links bellow.

Ceramic suspension formulation | Additive manufacturing of boron carbide | Dissertation slides