Feasibility and Limitations of the Advanced Replica Process for Bioactive Glasses

The replica process is a frequently used route to manufacture porous ceramics or glasses over a wide range of porosity, usually specified in ppi (pores per inch) for foams. However, the use of random open‐cell foam templates limits the reproducibility and systematic evaluation of process parameters. Therefore, the advanced replica technique is proposed, in which periodic, 3D‐printed templates are utilized to manufacture isotropic porous lattices. The templates, consisting of a homogenous network of 29 K cells, were VAT photopolymerization printed with a commercial polymer resin to systematically investigate their influence of processing conditions and material variables on manufacturing. Three glasses (the well‐known bioactive 45S5 and 13–93, and a novel phosphate glass P45K9) were tested in this approach. They were prepared by melt synthesis and milled to a particle size of approx 4 µm, which enabled the preparation of slurries with comparable viscosities. The heat treatment was adjusted to the material and the stability of the structures, which depends on the number of coating layers and the shrinkage of the respective glass. Despite a different shrinkage behavior of the three glasses, similar porosities in the range of 83%–88% were achieved. This work highlights the chances of the advanced replica process.