Bioactive borate glass coatings for titanium alloys

Bioactive borate glass coatings have been developed for titanium and titanium alloys. Glasses from the Na 2 O–CaO–B 2 O 3 system, modified by additions of SiO 2 , Al 2 O 3 , and P 2 O 5 , were characterized and compositions with thermal expansion matches to titanium were identified. Infrared and X-ray diffraction analyses indicate that a hydroxyapatite surface layer forms on the borate glasses after exposure to a simulated body fluid for 2 weeks at 37°C; similar layers form on 45S5 Bioglass ® exposed to the same conditions. Assays with MC3T3-E1 pre-osteoblastic cells show the borate glasses exhibit in vitro biocompatibility similar to that of the 45S5 Bioglass ® . An enameling technique was developed to form adherent borate glass coatings on Ti6Al4V alloy, with adhesive strengths of 36 ± 2 MPa on polished substrates. The results show these new borate glasses to be promising candidates for forming bioactive coatings on titanium substrates.