A novel hybrid 3D printing process to create complex ceramic structures has been developed in what is being referred to as a ‘groundbreaking’ PhD project at the University of Applied Sciences and Arts of Southern Switzerland (SUPSI). Marco Pelanconi made the breakthrough, a doctoral candidate at of Professor Alberto Ortona at the University of Padua.
The Hybrid Materials Laboratory (HM Lab) at SUPSI University has been conducting research in ceramic 3D printing materials for two decades. In 2019, Professor Ortona demonstrated the potential that porous 3D prints possess for ceramic materials. Pelanconi has successfully defended his PhD thesis in the same research area.
As his dissertation project, Pelanconi developed an optimised 3D printing process to produce complex ceramic architectures. The approach involves 3D printing of polymeric preforms with high microporosity through SLS, combined with infiltration with preceramic polymers. Pyrolysis is then used to obtain a polymer-to-ceramic conversion at around 1000°C. A final densification is performed via molten silicon infiltration to achieve ceramic parts at high density according to the university.
The Sintratec Kit was used in the project. According to Pelanconi, the kit’s open parameters were useful for the project. He said: “The kit allowed us to change a lot of printing parameters, including powder surface temperature, layer thickness, laser speed, hatching spacing, and more, making it easy to control the porosity of the 3D printed parts.”
By varying these factors, Pelanconi says he was able to achieve an ideal porosity and high part quality, crucial for further infiltration.
To illustrate how the method could be used for complex shapes, Pelanconi focused his research on two cylindrical porous structures with different topologies: a rotated cube and a gyroid. After printing in PA12 and subsequent conversion into ceramics, the resulting parts exhibited ‘outstanding mechanical and thermal properties’ according to the mechanical engineer.
Pelanconi says the prints maintained their shape without distortion or macrocracks despite a shrinkage of -25%. He also said that the parts biaxial strength of 165 MPa could still be increased through further process optimisation.
Speaking about the potential of complex ceramic architectures, Pelanconi added: “These classes of materials offer unmatched thermo-mechanical properties that cannot be provided by steels, such as high temperature resistance, high oxidation resistance, high thermal shock resistance and high strength.”
The university says that the approach, carried by Pelanconi within the HM Lab, could be exploited by the high-tech industry thanks to the different ceramic materials obtainable from a range of preceramic polymers.