Technical ceramics in additive manufacturing

Technical ceramics, as opposed to artisanal or artistic ceramics, is a material that has been used for centuries in many industrial sectors. They are renowned for their temperature resistance, hardness and mechanical properties. In the additive manufacturing sector, ceramics are less popular than polymers or metals and remain a niche market, even if 3D technologies are particularly interesting for materials. Indeed, due to their characteristics, technical ceramics are difficult materials to shape and additive manufacturing represents a relevant alternative in the creation of complex geometries. Currently compatible with photopolymerization, powder bed and extrusion processes, ceramics offer multiple advantages to manufacturers, laboratories and research centers. Among them, the Belgian Ceramics Industry Research Center (CRIBC), which has relied on several 3D printing processes, including that of the French manufacturer Pollen AM.

For twenty years, the CRIBC has been investing in additive manufacturing to be able to manufacture parts with complex geometries. Indeed, technical ceramics are fragile and refractory materials and therefore intrinsically difficult to shape. When it comes to creating complex geometries using conventional processes, lead times are extended and the cost of a part is greatly impacted. The promise of additive manufacturing lies precisely in overcoming this pitfall: offering complex geometries while preserving the properties of ceramics, regardless of the material used.

Ceramic is a difficult material to shape. Thanks to additive manufacturing, complex geometries can be imagined (photo credits: 3Dnatives)

Technical ceramics on the market

There is currently a very diverse range of technical ceramics that can meet different markets and needs. The family most used in additive manufacturing is undoubtedly oxidized ceramics which, as their name suggests, are composed of metal oxide such as alumina or zirconia. They are used in the medical field for the production of bone implants as well as in the field of watchmaking. Next come non-oxidized ceramics with nitrided materials which combine good mechanical performance and temperature resistance, and excessively hard carbides often used for their tribological resistance. Silicon carbide, for example, is three times harder than steel.

In additive manufacturing, manufacturers can use different technological approaches to design their parts, but they are not all compatible with all families of ceramics. The CRIBC tested several ceramic 3D printing processes and was able to compare the quality of the parts obtained, their characteristics and their performance. Fabrice Petit, Program Manager Manufacturing Processes at CRIBC, explains: “There are many additive technologies for ceramics, but none replaces the others. The choice will be made according to the desired application. Stereolithography, for example, will be ideal for small parts with little aperture and low mass. Powder bonding allows the design of large but very porous parts, so its use is rather limited. In my opinion, the extrusion processes remain the most interesting, and particularly the Pollen AM technology because it is based on materials in the form of granules found in the injection molding industry. It is an open machine that reduces the cost of materials and opens up the field of possibilities.

Example of part 3D printed in zirconia by the CRIBC on a Pollen AM machine (photo credits: 3Dnatives)

The choice of Pollen AM technology

CRIBC mainly works on oxides with Pollen AM technology, although it is beginning to use nitrides to meet temperature requirements. It also plans to test carbides, including tungsten carbide. The research center evaluates the technology and characteristics of parts, whether they are lattice structures, nitride micro-turbines, tungsten carbide cutting tools, etc. And the result is satisfactory: Pollen AM’s extrusion process produces quality parts with very good surface finishes that can be mechanically stressed.

This is often the challenge of ceramic additive manufacturing: you have to pay attention to the porosity of the parts because if it is too high, the mechanical performance will be insufficient. The surface condition is a key point because if it is degraded, this will lead to cracks and therefore to a part which will break after stress. In any case, Fabrice Petit develops, “Ceramic additive manufacturing offers, like all 3D technologies, greater design freedom. I think it’s even more relevant with ceramics because of its characteristics and properties.

Finally, Pollen AM’s extrusion process has the advantage of being cleaner and more convenient than other ceramic 3D printing technologies. Powder bed processes, for example, present a health risk for the operators, in particular for their respiratory tracts, but also require a certain installation in the working environment; The Pollen AM machine can be used in a closed office. Fabrice Petit concludes. “From a practical point of view, PAM technology has serious advantages over other technologies. Add to that the compatibility of materials, their cost and the quality of the parts obtained, it is an ideal ceramic additive manufacturing technology. You can find more information about technical ceramics and PAM technology HERE.

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