Investigation of properties, corrosion and bioactivity of novel BaO added phosphate glasses and glass-ceramic coating on biomedical metallic implant materials

Abstract

This thesis deals with the synthesis, characterization and investigation of properties of phosphate glasses with composition (26-x)Na2O-xBaO-29CaO-45P2O5 (x = 0,5,10,15 mol%) and coating of 11Na2O-15BaO-29CaO-45P2O5 glass on biomedical metallic implant materials such as stainless steel 316 L, duplex stainless steel (DSS) 2205 and Ti6Al4V alloy. Glasses were prepared by melt-quenching technique and glass was coated by thermal enamelling technique. Effect of BaO addition on the structural, mechanical, thermal, optical, dissolution and in vitro bioactivity properties of bioactive Na2O-CaO-P2O5 glasses was the main subject of study. The glasses were synthesized at three melting temperatures such as 1000, 1100, 1200oC. Glasses prepared at 1200oC were having lower brittleness attributing to the plastic flow of deformation. Brittleness of glasses prepared at higher melting temperatures has decreased with BaO addition, whereas thermal stability, glass forming ability and optical band gap energy have increased. Dissolution rate of glasses in deionized water was reduced by three orders of magnitude with BaO content of 15 mol %. In vitro bioactivity studies of glasses were carried out in Phosphate buffer saline (PBS) and Hank’s balanced salt (HBS) solutions for 28 days. Bioactivity of glasses was improved with BaO content. Faster hydroxyapatite (HAp) formation was observed in HBS solution in comparison with PBS. All the coatings have glass-ceramic nature with porous morphology. DSS and coated 316 L were having higher electrochemical corrosion resistance in HBS solution among uncoated and coated substrates respectively. DSS 2205 can be an alternative for 316 L and Ti6Al4V for biomedical applications due to its better corrosion resistance. In vitro bioactivity test of glass coated samples were conducted in HBS solution for 14 days and formation of amorphous calcium-phosphate (ACP) layer on coatings was noticed.