Immersion behavior of RF magnetron-assisted sputtered hydroxyapatite/titanium coatings in simulated body fluid

The focus of the present study was on the dissolution/degradation behavior of a series of magnetron-sputtered, single-layered HA/Ti coatings on Ti-6Al -4V substrate immersed in SBF. Changes in coating morphology, crystal struc ture, and adhesion strength with immersion time are characterized XRD, FTIR , and LVSEM results consistently indicate that highly crystalline monolithi c KCl coating is very dissolvable in SBF. The monolithic KA coating is larg ely delaminated in 3 weeks and entirely peeled off the substrate in 7 weeks . The dissolution is even greater for 95HA/5Ti coating, which severely disi ntegrated in only 1 week. The amorphous-like coatings sputtered from target s comprising 10 vol % or more Ti, however, appeared almost intact, and thei r adhesion strengths, which were all higher than 60 MPa, did not change muc h (within 10%) even after 14 weeks of immersion. The coatings from targets comprising roughly 10-50 vol % Ti combine advantages of high and nondeclini ng adhesion strength, high resistance to SBF attack, and possibly much high er bioactivity (with large amounts of Ca, P, etc., dissolved in the coating s) than that of Ti. (C) 1999 John Wiley & Sons, Inc.