The New Ceramic 3D Printing Process Realizes High-precision Microstructure And Multi-material Integrated Manufacturing

Recently, Carnegie Mellon University reported a new ceramic 3D printing technology (3D-AJP) based on aerosol jet, which can be used to manufacture high-performance ceramic materials with complex microstructures.Through a nano-printing process with no binder and no auxiliary support, this technology realizes the manufacture of complex ceramic structures on a micro-scale (minimum characteristic size of 20 microns), and the shrinkage rate after sintering is extremely low (2-6%).The research shows the application potential of this technology in many fields such as photocatalysis, biosensor and microelectronic packaging.

Schematic diagram of 3D aerosol jet printing (3D-AJP): 3D nano-printing of complex three-dimensional ceramic microstructures with near-zero shrinkage aerosol jet.A) The ultrasonic atomizer in the AJ nano-particle printer is used to atomize the ink based on zinc oxide (ZnO) nano-particles. The enlarged image shows the nano-particles (diameter≈20 nm) and individual droplets in the ink bottle.B) Aerosols (mist) pass through the pipeline system and are transmitted to the deposition nozzle using inert gas.The enlarged image shows the loose arrangement of ink streams focused by the sheath gas on the substrate.C) Fast drop-by-drop free-form printing without auxiliary support.The enlarged image shows the mechanism by which the inclined structure can be constructed without auxiliary support.The observed shrinkage rate after sintering is extremely low, which proves its manufacturing effect close to net forming.

The core of 3D-AJP technology is the use of aerosol jet printing to accurately deposit nano-particle ink into complex three-dimensional microstructures.It uses almost binder-free nano-particle ink, avoiding the high shrinkage and structural defects caused by binder removal in traditional manufacturing.This technology can realize complex structures with a minimum characteristic size of 20 microns, such as micro-columns, spirals, and lattices, and has an aspect ratio of up to 30:1.In addition, it also has the ability to print multiple materials, and can integrate different ceramic materials (such as zinc oxide, titanium dioxide, and zirconia) in the same structure.

Ceramics are manufactured through other 3D printing technologies (such as extrusion printing, 2PP, and DLS).It shows the precursor ink that uses a high content of adhesive (left) and a minimum content of adhesive (right) in ceramic manufacturing.

The linear shrinkage rate of this technology after sintering is only 2-6%, which is much lower than that of traditional technologies (such as 15-43% in 3D printing).In addition, 3D-AJP technology can quickly manufacture complex ceramic structures without complex post-processing steps.The research demonstrates the application potential of 3D-AJP technology in many fields.

The CAD design realized by 3D aerosol jet printing technology is compared with the zinc oxide (ZnO) microcrystalline grid manufactured.Optical image of a high aspect ratio microcrystalline grid (height of 1 cm, width of 600 microns).Top view of microcrystalline grids of different ceramic materials (i.e. zirconia ZrO₂) (left) and inclined scanning electron microscope (SEM) view (right).

In the field of photocatalysis, researchers manufactured a ZnO (zinc oxide) microcrystalline lattice structure and used it for photocatalytic degradation of methyl orange dyes.The results show that compared with the traditional block ZnO, the ZnO microcrystalline lattice manufactured by 3D-AJP has increased the photocatalytic efficiency by 400%, showing a significant performance improvement.

In the field of biosensor, a sensor for detecting Her2, a biomarker of breast cancer, has been manufactured using 3D-AJP technology.The sensor can detect Her2 biomarkers within 22 seconds, with a detection limit as low as 0.0193 femtomoles (fm), showing extremely high sensitivity.

Aerosol jet nano-printed complex single-material and two-material ceramic microstructures.A) CAD design of multi-spiral microstructure (top) and scanning electron microscope (SEM) image (bottom); B) CAD design of pyramid-shaped microcrystalline lattice (top) and SEM image (bottom); C) CAD design of zinc oxide (ZnO) wavy micro-wall (top) and SEM image (bottom).The scales are all 500 microns.D) The printed bimaterial pyramid-shaped microcrystalline lattice (left) and energy scattering X-ray spectroscopy (EDX) analysis showed zirconium (Zr) and zinc (Zn) on different printing layers (right).E) Other bimaterial microcrystals, including titanium dioxide (TIO₂) at the top and ZnO at the bottom, EDX analysis confirmed their composition.At the same time, another bimaterial structure is shown, namely TIO₂ at the top and zirconia (ZrO₂) at the bottom.F) Mixed ceramic materials, including alumina (AlOo₃), TIO₂ and ZnO, EDX analysis shows that titanium (Ti), aluminum (Al) and zinc (Zn) are evenly distributed in a single lattice.

In addition, 3D-AJP technology also demonstrates the ability to integrate multiple ceramic materials such as ZnO, TiO2, and ZrO2 in the same structure, providing new possibilities for the manufacture of high-performance catalytic, sensing, and photoelectric equipment.

In general, 3D-AJP technology realizes the high-precision manufacturing of complex ceramic microstructures through the nano-printing process without binder, and the shrinkage rate after sintering is extremely low.This technology not only shows significant performance improvements in the fields of photocatalysis and biosensor, but also provides new possibilities for the manufacture of multi-material composite structures.3D-AJP technology is expected to be widely used in microelectronic packaging, structural materials, biomedical sensing, thermal barrier coating and filtration technology, opening up a new direction for the manufacture of high-performance ceramic materials.