The Manufacturing Challenge Overcome with Baikalox® SMA6?
Combining dissimilar materials inside dense ceramics has been a long-standing hurdle: conventional routes rarely deliver microstructural precision and preserved density. Additive manufacturing helped, but robocasting in air still constrains geometry and material pairings. The promising alternative—embedded 3D printing within a self-healing support—had proved difficult to translate to dense inorganic systems.
That changed when Imperial College London demonstrated an embedded route built on Baikowski’s SMA6.
In work titled Embedded 3D printing of microstructured multi-material composites and published in Matter (February 2024) , the team extruded complex architectures into a self-healing ceramic gel that yields to the nozzle and rapidly recovers, then—after controlled drying, debinding, and sintering—converts to dense alumina.
The result is defect-free, multi-material composites with sharp interfaces, opening design space for internal reinforcements and microchannels that conventional processing couldn’t reach.
Why SMA6 Alumina Made the Difference?
🌟 Ultra-Fine Particle Engineering
The choice of Baikalox® SMA6 with d₅₀ ≈ 0.2 µm proved decisive.
Its ultra-fine, tightly controlled particle-size distribution gives you the rheological “dials” you need—viscosity, yield stress, and recovery—so the nozzle passes cleanly and the matrix reliably self-heals.
The approach relies on gels with >25 vol% powder (matrix prepared at 7:3 wt/wt Al₂O₃:Pluronic), which supports dense sintering of both matrix and inks.
Packing is uniform enough to reach ~4–6% porosity after firing, and dispersion is controlled so interfaces remain sharp and porosity-free between embedded structures and the alumina matrix.
🌟 Processing Excellence
Before dispersion in Pluronic F127, SMA6 was sieved through a 100 µm plastic mesh to reduce agglomerates. With an appropriate dispersant (about 1 wt% relative to Al₂O₃), the powder forms a homogeneous, thermally reversible gel whose viscoelastic profile is well-matched to embedded printing.
How Does This Translate into Applications?
To validate the approach, the team demonstrated two use cases: co-sintered steel architectures that boost fracture energy without sacrificing strength, and sacrificial-graphite microchannels that deliver functional internal cooling in dense alumina.
🌟 1- Steel-Reinforced Alumina
SMA6 lets the steel architecture survive from printing to sintering, delivering real mechanical gains without giving up strength:
- Flexural strength: 155–289 MPa
- Fracture toughness: 3.3–4.0 MPa·m¹ᐟ²
- Work of fracture: up to 3.6 kJ/m² for auxetic lattices (≈ two orders of magnitude above unreinforced alumina, ~30 J/m²)
Why it works: auxetic frameworks steer cracks and spread plasticity in steel, boosting energy absorption while maintaining strength.
🌟 2- Advanced Thermal Management Systems
With sacrificial graphite printed inside the SMA6 matrix, you get dense alumina divided by clean, functional microchannels:
- Circular cross-sections approximately 200 μm diameter after sintering
- Wall thicknesses reduced to 50 μm between adjacent channels
- Proven cooling performance: temperature reduction from 119°C to 62°C in 200 seconds when flowing cold water through channels in a heated 2.6 × 2.6 × 1.5 cm³ alumina cube
These capabilities open new pathways for manufacturing thermal management systems with complex internal geometries previously impossible to produce.
How Did the Material Perform in the Study?
In short, the microstructure stayed tight and the printed features held their shape after firing. Overall density landed around 94–96% (≈ 4–6% porosity). Post-sinter, filaments remained in the ~70–260 µm range, and interfaces were sharp and porosity-free, as confirmed by SEM/EDX.
What Processing Parameters Were Reported?
Keep the window, and the parts keep their fidelity:
- Drying: 72 ± 3% RH, ~32 °C, ~2 weeks (on 16 × 16 × 16 mm cubes)
- Debinding: 1 °C·min⁻¹ → 350 °C (1 h); then 2 °C·min⁻¹ → 500 °C (2 h)
- Sintering: steel-reinforced parts to 1,450 °C (after a 600 °C step); microchannel parts to 1,550 °C
Which Conditions Make Embedded Printing Viable?
Five things have to line up—and SMA6’s PSD/dispersion helps tick each box:
- Viscoelastic match between ink and matrix
- Low matrix breaking stress so the nozzle can move freely
- Rapid matrix recovery so features don’t slump
- High ink yield stress to lock in filament geometry
- High inorganic content (matrix + inks) for dense, defect-free sintering
How Adaptable Is It Across Industries?
The method accommodates materials with very different properties within the Additive Manufacturinge SMA6 matrix, indicating broad adaptability across material systems.
Target Applications:
- Structural ceramics: aerospace, defense, automotive components requiring exceptional toughness without sacrificing strength
- Thermal management: electronics and energy systems with internal cooling channels
- Multi-functional devices: components combining structural and thermal functions
- Metamaterial-reinforced composites: architected structures with tailored responses
Why Partner with Baikowski?
Every Additive Manufacturing line has its own window. SMA6 excelled in this study, and Baikowski’s wider portfolio includes specialized alumina grades for diverse processes.
We help you tune powder, rheology and sintering: custom formulations that match your process parameters, collaborative optimization to boost yield and performance, consistent quality batch after batch.
Frequently Asked Questions
Can this process work with other alumina grades besides SMA6?
Yes—in principle for other ultra-fine grades—but each system needs its own rheology optimization. The key is a stable, high-solid gel with matched viscoelastic properties. Our team can help identify the optimal Baikowski grade for your application.
Why is particle size so critical for this application?
The 0.2 µm d₅₀ PSD enables precise rheological control near the gel transition, supports >25 vol% solids for dense sintering, and minimizes interfacial mixing—so boundaries between embedded structures and matrix remain sharp.
How does this compare to conventional ceramic composite manufacturing?
The auxetic steel-reinforced alumina achieved work of fracture values (3.6 kJ/m²) orders of magnitude higher than unreinforced alumina while maintaining comparable strength (155-289 MPa). This represents a significant breakthrough in overcoming the typical strength-toughness trade-off in ceramics.
What are the practical size limitations?
Feature size depends on nozzle diameter and matrix rheology. The study achieved filament diameters from 70-260 μm after sintering, with wall thicknesses between microchannels reduced to 50 μm. Finer features may be possible with smaller nozzles and optimized gel formulations.
Is the process ready for industrial production?
It’s repeatable at laboratory scale. Industrialization requires application-specific tuning of the powder–rheology–sintering trio, which our technical team can support.
Take the Next Step
Developing advanced ceramic composites or exploring novel AM approaches? Baikowski offers comprehensive alumina solutions backed by dedicated technical support.
💬 Connect with our Experts and download our 3D Printing White Paper — powder selection and process optimization for ceramic AM (including SMA6 insights)