Effect of processing on microstructure, mechanical properties and dissolution in simulated body fluid of 45S5 bioglass coatings deposited by Suspension High Velocity Oxy Fuel (SHVOF) thermal spray

45S5 Bio-glass is a soda lime phosphosilicate glass (Na2O-CaO-P2O-SiO2) that reacts with the physiological fluid and has the characteristic of bonding with hard and soft tissues when implanted in the body. 45S5 bio-active coatings were deposited by suspension high velocity oxy fuel thermal spray (S-HVOF) using a water + isopropanol (IPA) based suspension. Three distinctly different coating microstructures were produced by altering the flame power from 25 to 50 and 75 kW. Deposition at lower flame power of 25 kW resulted in a thin coating while thick, porous coatings were deposited at medium and high flame powers of 50 and 75 kW, and all of the coatings were entirely glassy, as examined by XRD. After soaking in simulated body fluid (SBF) coatings deposited at 50 and 75 kW were uniformly covered by hydroxyapatite (HA) after three days but no HA formed on coating deposited at 25 kW, not even after for longer time of immersion in SBF. EDX analysis of the precipitated HA on 45S5 coating deposited at 50 kW showed that after soaking in SBF for seven days the glass was partially resorbed; whereas, the coating produced from the high power of 75 kW performed the best in SBF.