Rational design of nonstoichiometric bioceramic scaffolds via digital light processing: tuning chemical composition and pore geometry evaluation

Bioactive ceramics are promising candidates as 3D porous substrates for bone repair in bone regenerative medicine. However, they are often inefficient in clinical applications due to mismatching mechanical properties and compromised biological performances. Herein, the additional Sr dopant is hypothesized to readily adjust the mechanical and biodegradable properties of the dilute Mg-doped wollastonite bioceramic scaffolds with different pore geometries (cylindrical-, cubic-, gyroid-) by ceramic stereolithography. The results indicate that the compressive strength of Mg/Sr co-doped bioceramic scaffolds could be tuned simultaneously by the Sr dopant and pore geometry. The cylindrical-pore scaffolds exhibit strength decay with increasing Sr content, whereas the gyroid-pore scaffolds show increasing strength and Young’s modulus as the Sr concentration is increased from 0 to 5%. The ion release could also be adjusted by pore geometry in Tris buffer, and the high Sr content may trigger a faster scaffold bio-dissolution. These results demonstrate that the mechanical strengths of the bioceramic scaffolds can be controlled from the point at which their porous structures are designed. Moreover, scaffold bio-dissolution can be tuned by pore geometry and doping foreign ions. It is reasonable to consider the nonstoichiometric bioceramic scaffolds are promising for bone regeneration, especially when dealing with pathological bone defects.

Thermal Behaviour in the Stereolithography Process for Al2O3 Ceramic Suspension

In the process of ceramic stereolithography, the polymerization process of acrylate is exothermic, resulting in changes to temperature of the slurry, which may affect the quality of green parts. In this work, the heat source input in simulation is based on the in-situ measurement of conversion rate and calculated polymerization exotherm. The simulation results showed that the different structures underwent a 1~3°C maximum temperature rise. A thermal infrared detector was used to capture the in-situ temperature changes in entire exposure surface for several structures during the photopolymerization process. The experimental data validated the simulation results and showed that the temperature change and distribution area in the process were related to the exposure structure. The discontinuous structure and the increase of structural boundary length could accelerate the thermal diffusion, thus reducing the heat concentration in the center. Polymerization rate rose marginally with the incident light intensity until at the intensity of 20 milliwatts. Besides, intensity had little effect on the temperature gradient from the center to the boundary of the exposure area. It is inferred that the additional temperature rise after the peak temperature is an indicator of the occurring of secondary photopolymerization during multilayer exposure. And for the same input energy, reducing the exposure intensity and increasing the exposure time to some extent may help improve the degree of secondary photopolymerization. This work provided valuable guidance for the study of the photopolymerization process and structural design of ceramic stereolithography.

Additive manufacturing revolution in ceramic microsystems

Purpose The purpose of this paper is to review possibilities of implementing ceramic additive manufacturing (AM) into electronic device production, which can enable great new possibilities. Design/methodology/approach A short introduction into additive techniques is included, as well as primary characterization of structuring capabilities, dielectric performance and applicability in the electronic manufacturing process. Findings Ceramic stereolithography (SLA) is suitable for microchannel manufacturing, even using a relatively inexpensive system. This method is suitable for implementation into the electronic manufacturing process; however, a search for better materials is desired, especially for improved dielectric parameters, lowered sintering temperature and decreased porosity. Practical implications Relatively inexpensive ceramic SLA, which is now available, could make ceramic electronics, currently restricted to specific applications, more available. Originality/value Ceramic AM is in the beginning phase of implementation in electronic technology, and only a few reports are currently available, the most significant of which is mentioned in this paper.