Hardness of bioactive glass film deposited on titanium alloy by pulsed laser deposition

Certain glasses which contain specific amounts of SiO2, Na2O, CaO and P2O5 (bioglasses) are of a limited number of materials forming strong chemical bonds with bone in vivo, while remaining stable under the harsh conditions encountered in the human body [1–7]. These glasses contain usually less than 60 mol% SiO2, and are of a high Na2O content and a high CaO/P2O5 ratio [5]. Such a composition produces a surface that becomes highly reactive when exposed to a water-containing environment, e.g. of the human body fluids [5]. Monolithic bioglasses are too brittle to be used in structural applications, e.g. as dental root implants. Poor fracture toughness and strength limited the use of these bulk materials to non-load-bearing implants. One way to overcome this problem is to coat a metallic implant with bioglass. The coating provides the bone bonding capacity while the metal substrate provides the structural support. For this reason, various methods were tested to coat metallic implants with glass. The success achieved by these methods is variable. The most commonly used techniques are enameling, electrophoresis, sol-gel, and plasma spraying. The main disadvantage of these methods is poor adhesion strength of the coating to substrate. Besides, electrophoresis and sol-gel methods are substrate specific.