Laser sintering and crystallization of a bioactive glass-ceramic

Glass-ceramics are formed from metastable glasses that crystallize to one or more ceramic phases upon heating. Most bioactive glass-ceramics require conventional sintering in an oven to devitrify due to slow crystallization kinetics. Apatite-mullite glass-ceramics can be crystallized at higher rates due to faster kinetics and are suitable for use with rapid sintering techniques. In particular, laser sintering is an attractive alternative to conventional heat treatment because the energy consumption is dramatically reduced and throughput time is extremely quick. Here, apatite-mullite glass-ceramics were examined in a preliminary study to elucidate the effects of laser sintering and crystallization of a bioactive glass-ceramic. The prospect of simultaneously laser enameling it to a titanium surface was also investigated. The laser power, laser traverse speed, and number of passes over the sample were varied. Minimum threshold values required to produce apatite and mullite were identified. Laser enameling of coatings on titanium showed that a smaller interfacial reaction zone occurs compared to conventional sintering but the coating was porous. This information can be used to develop more suitable glass compositions.