 | Paolo Colombo |
Additive manufacturing of Ceramics from Preceramic Polymers
Additive manufacturing of ceramics is somewhat limited by their high melting temperatures and the processing issues related to handling of feedstocks containing a large volume of particles. Processing slurry-based feedstocks, in fact, poses several challenges: a high amount of powder is required to promote densification and results in high viscosity, scattering and sedimentation phenomena in vat photopolymerization processes, as well as clogging problems at the nozzle for extrusion-based processes. Some of these issues can be solved or mitigated when using all liquid, precursor-based feedstocks. Our research activities have therefore focused on the use of preceramic polymers.
Preceramic polymers are precursors for ceramic phases of different composition. They convert into nano-structured ceramic materials in the system Si(X)OCN (with X = Al, Ti, Zr, etc.), also called PDCs or Polymer-Derived-Ceramics, by high temperature pyrolysis. The resulting materials can have useful structural and functional properties.
This talk will discuss the fabrication of (mainly) porous structures starting from pure preceramic polymers (e.g. silicone resins) or silicone resins plus reactive fillers to produce advanced silicate ceramic phases, including bioceramics and Ceramic Matrix Composites, suitable for different potential applications.
Different additive manufacturing techniques were used to fabricate components ranging in size from the sub-micron to the tens of centimeters, including direct ink writing, digital light processing, two photon polymerization, robotic arm manufacturing and volumetric additive manufacturing.
Advantages and disadvantages of the different processing techniques employed, in relation to the use of preceramic polymers, will be discussed, and examples of produced and characterized structures for potential use in different applications will be presented.
Interview with Paolo Colombo
- What is the central theme of your plenary lecture at InterPore2026?
The topic of my talk deals with the Additive Manufacturing of Porous Ceramics, specifically derived from Precursors. These precursors include preceramic polymers, sol-gel systems and geopolymers. Using a precursor approach, issues that commonly arise when using particulate-based systems (i.e., ceramic powders) can be avoided, such as sedimentation, scattering and absorption of radiation (for photopolymerization), nozzle clogging (for extrusion-based manufacturing approaches), etc. This approach leads to the possibility, for instance, of employing novel Volumetric Additive Manufacturing technologies for fast production of parts.
- What first interested you in the field of porous ceramics?
As an engineer, I am aware that porous materials greatly extend the range of properties that are available for the design of advanced components. By controlling the characteristics of the porosity of a component, an optimal combination of properties (e.g., density, permeability, thermal conductivity, etc.) can be achieved. As someone said: when dealing with porous materials, less is more! What attracted me to porous ceramics is their versatility, their presence in several components used for a variety of applications, and the wide range of manufacturing technologies that can be employed to manufacture them.
- How has additive manufacturing changed the way we design porous materials?
Additive manufacturing has significantly impacted the design and production of porous materials. In fact, it allows to achieve:
1) Precise control over porosity: additive manufacturing allows for exact control over pore size, shape, and distribution within a material. This level of precision was difficult or impossible to achieve with traditional manufacturing methods.
2) Complex geometries: It's now possible to create intricate internal structures and complex pore networks that were previously extremely difficult or impossible to produce.
3) Customization: Designers can easily tailor porous materials for specific applications, adjusting properties like permeability, surface area, and mechanical strength.
4) Gradient structures: Additive manufacturing enables the creation of materials with varying porosity throughout, allowing for optimized performance in different regions of the same part.
- What applications do you find most exciting for extreme-environment porous materials and what challenges remain to bring them to real-world deployment?
The development of extreme-environment porous materials is indeed an exciting field with numerous potential applications. In my opinion, some of the most promising applications and the challenges these components face include:
Aerospace heat shields: Porous materials for thermal protection systems in spacecraft re-entry.
High-temperature filters: For use in industrial processes or exhaust systems in extreme conditions.
Nuclear reactor components: Porous materials for fuel cells or radiation shielding in nuclear environments.
About Paolo Colombo
Paolo Colombo is a professor of Materials Science and Technology at the Department of Industrial Engineering, University of Padova, Italy. He is also an Adjunct Professor at the Pennsylvania State University, an Honorary Professor at University College London, UK, an Honorary Researcher at the Henan Academy of Sciences, CN and an Honorary Professor at Xi’an Jiaotong University, CN.
He is an Academician of the World Academy of Ceramics, the European Academy of Sciences, Academia Europaea, the Italian Academy of Engineering and Technology, and a Fellow of the American Ceramic Society, the Institute of Materials, Minerals and Mining, the European Ceramic Society, and the International Core Academy of Sciences and Humanities. He received several international awards (Pfeil Award, Edward C. Henry Award, Verulam Medal & Prize, Bridge Building Award, ECerS-ACerS Joint Award). He is Past President of the International Ceramic Federation and Vice President of the Italian Ceramic Society.
