Interfaces in graded coatings on titanium‐based implants

Abstract

Graded bilayered glass-ceramic composite coatings on Ti6Al4V substrates were fabricated using an enameling technique. The layers consisted of a mixture of glasses in the CaO-MgO-Na2O-K2O-P2O5 system with different amounts of calcium phosphates (CPs). Optimum firing conditions have been determined for the fabrication of coatings having good adhesion to the metal, while avoiding deleterious reactions between the glass and the ceramic particles. The final coatings do not crack or delaminate. The use of high-silica layers (>60 wt % SiO2) in contact with the alloy promotes long-term stability of the coating; glass-metal adhesion is achieved through the formation of a nanostructured Ti5Si3 layer. A surface layer containing a mixture of a low-silica glass (~53 wt % SiO2) and synthetic hydroxyapatite particles promotes the precipitation of new apatite during tests in vitro. The in vitro behavior of the coatings in simulated body fluid depends both on the composition of the glass matrix and the CP particles, and is strongly affected by the coating design and the firing conditions.

Direct ink writing of highly porous and strong glass scaffolds for load-bearing bone defects repair and regeneration

“…The sintered periodical scaffold consisted of struts with diameters of 75 μm and pores of 200 μm. The softening point of the glass is ~610°C [25], and the scaffolds were subjected to a binder burnout process at 600°C for 2 hours. Next they were sintered at 700°C for 1 hour to densify the glass filament while avoiding crystallization or deformation of the structure.…”

“…The glass selected is the bioactive 6P53B composition (in wt%: 52.7 SiO 2 , 10.3 Na 2 O, 2.8 K 2 O, 10.2 MgO, 18.0 CaO, 6.0 P 2 O 5 ), a modified version of the original 45S5 glass [4]. This bioactive glass has shown significant advantages in the preparation of coatings on metallic implants to enhance the osteointegration of Ti and for the fabrication of polymer/glass composites [24] because of its relatively better stability in aqueous environments [25, 26]. The work focused on the rheological properties of the glass ink, and in vitro degradation and mechanical response of the glass scaffolds in a simulated body fluid (SBF).…”

Effect of strontium substitution on the structure, ionic diffusion and dynamic properties of 45S5 Bioactive glasses

“…Due to the compositional dependence of bioactivity and tunability of the physical and chemical properties, functionally graded bioactive coatings based on these bioactive glasses have been produced on metal implants to provide simultaneous enhancement of adhesion at the metal/glass interface and bioactivity toward the surface [10,11]. The functional graded coating was achieved by varying the glass composition, hence their thermal, mechanical properties, chemical durability and bioactivity in a systematic manner.…”

Glass-based coatings on biomedical implants: a state-of-the-art review

“…The TEC of the well-known 45S5 Bioglass (15×10 −6∘ C −1 ) is significantly higher than that of titanium alloys (about 9×10 −6 ∘ C −1 ) and alumina (about 8×10 −6∘ C −1 ), which are commonly used to fabricate orthopaedic and dental implants: therefore, the need has emerged to develop new glass formulations with a more suitable TEC for use as coating materials. In this regard, bioactive glasses belonging to the SiO 2 -CaO-MgO-Na 2 O-K 2 O-P 2 O 5 system have been widely investigated to match the TEC of the Ti6Al4V alloy [14][15][16]. Partial replacement of Na 2 O and CaO with K 2 O and MgO, respectively, was the most common strategy to design and adjust the TEC of the glass in a controlled way [14].…”