



@article {2625,
	title = {Effect of hydroxyapatite thickness on metal ion release from Ti6Al4V substrates},
	journal = {BiomaterialsBIOMATERIALS},
	volume = {17},
	year = {1996},
	note = {Cited By (since 1996): 62Export Date: 21 November 2012Source: ScopusCODEN: BIMADdoi: 10.1016/0142-9612(96)89655-4PubMed ID: 8938233Language of Original Document: EnglishCorrespondence Address: Sousa, S.R.; INEB, Praca do Coronel Pacheco 1, 4050 Porto, PortugalChemicals/CAS: Alloys; Biocompatible Materials; Durapatite, 1306-06-5; titanium alloy (TiAl6V4), 12743-70-3; Titanium, 7440-32-6References: Barbosa, M.A., Electrochemical impedance studies on calcium phosphate-metal interfaces (1991) Bioceramics, 4, pp. 325-333. , Bonfield W, Hastings GW, Tanner KE, eds. London: Butterworth-Heinemann;Sousa, S.R., Barbosa, M.A., Electrochemistry of AISI 316L stainless steel in calcium phosphate and protein solutions (1991) J Mater Sci: Mater Med, 2, pp. 19-26; 
Sousa, S.R., Barbosa, M.A., Corrosion resistance of titanium cp in saline physiological solutions with calcium phosphate and proteins (1993) Clin Mater, 14, pp. 287-294; 
Li, P., De Groot, K., Calcium phosphate formation within sol-gel prepared titania in vitro and in vivo (1993) J Biomed Mater Res, 27, pp. 1495-1500; 
Li, P., Kangasniemi, I., De Groot, K., Bonelike hydroxyapatitc induction by a gel-derived titania and a titanium substrate (1994) J Am Ceram Soc, 77, pp. 1307-1312; 
Ducheyne, P., Healy, K.E., The effect of plasma-sprayed calcium phosphate ceramic coatings on the metal ion release from porous titanium and cobalt-chromium alloys (1988) J Biomed Mater Res, 22, pp. 1137-1163; 
Weng, J., Liu, X., Zhang, X., Li, X., Thermal decomposition of hydroxyapatite structure induced by titanium and its dioxide (1994) J Mater Sci Lett, 13, pp. 159-161; 
Castro Ribeiro, C., Barbosa, M.A., Influence of metal ions on the dissolution behaviour of hydroxyapatite (1991) Bioceramics, 4, pp. 145-153. , Bonfield W, Hastings GW, Tanner KE, eds. Butterworth-Heinemann; 
ASTM G61-86, standard test method for: Conducting cyclic potentiodynamic polarization measurements for localized corrosion susceptibility of iron, nickel, or cobalt based alloys (1989) Annual Book of ASTM Standards, pp. 345-361. , 03.02. Philadelphia, PA: American Society for Testing and Materials; 
ASTM G 31-72 e1, standard practice for: Laboratory immersion corrosion testing of metals (1989) Annual Book of ASTM Standards, pp. 176-186. , 03.02. Philadelphia, PA: American Society for Testing and Materials; 
Barbosa, M.A., Surface layers and the reactivity of metallic implants (1992) Biomaterials - Hard Tissue Repair and Replacement, pp. 257-283. , Muster D et al. ed. Amsterdam: Elsevier Science Publishers BV; 
Rivero, D.P., Fox, J., Skipor, A.K., Urban, R.M., Galante, J.O., Calcium phosphate-coated porous titanium implants for enhanced skeletal fixation (1988) J Biomed Mater Res, 22, pp. 191-201; 
Oonishi, H., Yamamoto, M., Ishimaru, H., The effect of hydroxyapatite coating on bone growth into porous titanium alloy implants (1989) J Bone Joint Surg, 71 B, pp. 213-216; 
Bourne, R.B., Rorabeck, C.H., Burkar, B., Kirk, P.G., Ingrowth surfaces - Plasma spray coating to titanium alloy hip replacements (1994) Clin Orthop Rel Res, 298, pp. 37-46; 
Oonishi, H., Noda, T., Ito, S., Effect of hydroxyapatite coatings on bone growth into porous titanium alloy implants under loaded conditions (1994) J Appl Biomater, 5, pp. 23-37; 
Moroni, A., Caja, V.L., Egger, E.L., Trinchese, L., Chao, E.Y.S., Histomorphometry of hydroxyapatite coated and uncoated porous titanium bone implants (1994) Biomaterials, 15, pp. 926-930; 
Bloebaum, R.D., DuPont, J.A., Osteolysis from a press-fit hydroxyapatite-coated implant (1993) J Arthroplasty, 8, pp. 195-202; 
Bloebaum, R.D., Beeks, D., Dorr, L.D., Savory, C.G., DuPont, J.A., Hofmann, A.A., Complications with hydroxyapatite particulate separation in total hip arthroplasty (1994) Clin Orthop, 298, pp. 19-26; 
Klein, C.P.A.T., Patka, P., Wolke, J.G.C., De Blieck-Hogervorst, J.M.A., De Groot, K., Long-term in vivo study of plasma-sprayed coatings on titanium alloys of tetracalcium phosphate, hydroxyapatite and α-tricalcium phosphate (1994) Biomaterials, 15, pp. 146-160; 
Reis, R.L., Monteiro, F.J., Hastings, G.W., Stability of hydroxyapatite plasma-sprayed coated Ti-6Al-4V under cyclic bending in simulated physiological solutions (1994) J Mater Sci: Mater Med, 5, pp. 457-462; 
Wang, B.C., Lee, T.M., Chang, E., Yang, C.Y., The shear strength and the failure mode of plasma-sprayed hydroxyapatite coating to bone: The effect of coating thickness (1993) J Biomed Mater Res, 27, pp. 1315-1327; 
Tranquilli Leali, P., Merolli, A., Palmacci, O., Gabbi, C., Cacchiolo, A., Gonizzi, G., Evaluation of different preparations of plasma-spray hydroxyapatite coating on titanium alloy and duplex stainless steel in the rabbit (1994) J Mater Sci: Mater Med, 5, pp. 345-349
},
	month = {1996///},
	pages = {397 - 404},
	publisher = {Elsevier Science Ltd},
	abstract = {The electrochemical dissolution behaviour of Ti6Al4V alloy coated with hydroxyapatite (HA) by plasma spraying was studied in Hank{\textquoteright}s balanced salt solution (HBSS) and compared with that of polished and grit-blasted passivated surfaces. Two different nominal thicknesses of HA (50 and 200 μm) were used. Taking a polished passivated surface as reference, grit blasting of the substrate increased the electrical charge used in the oxidation of Ti6Al4V alloy at constant potential, as a result of increased surface area. However, only HA coatings with a thickness of 200 μm were capable of reducing the charge to values lower than those measured for polished surfaces. Electrochemical impedance spectroscopy has also shown that only 200 μm thick coatings are effective in reducing the oxidation rate of the substrate. Furthermore, in potentiostatic experiments the 50 μm thick coating detached from the substrate, which did not occur with the 200 μm thick coating. However, after 6 months immersion in HBSS, detachment occurred in some regions of both coatings. No titanium, aluminium or vanadium were detected in solution by electrothermal atomic absorption spectroscopy. These data indicate that HA is an effective barrier to metal ion release, even for the thinner coatings, due to formation of metal phosphates or to incorporation of metal ions in the HA structure.The electrochemical dissolution behaviour of Ti6Al4V alloy coated with hydroxyapatite (HA) by plasma spraying was studied in Hank{\textquoteright}s balanced salt solution (HBSS) and compared with that of polished and grit-blasted passivated surfaces. Two different nominal thicknesses of HA (50 and 200 μm) were used. Taking a polished passivated surface as reference, grit blasting of the substrate increased the electrical charge used in the oxidation of Ti6Al4V alloy at constant potential, as a result of increased surface area. However, only HA coatings with a thickness of 200 μm were capable of reducing the charge to values lower than those measured for polished surfaces. Electrochemical impedance spectroscopy has also shown that only 200 μm thick coatings are effective in reducing the oxidation rate of the substrate. Furthermore, in potentiostatic experiments the 50 μm thick coating detached from the substrate, which did not occur with the 200 μm thick coating. However, after 6 months immersion in HBSS, detachment occurred in some regions of both coatings. No titanium, aluminium or vanadium were detected in solution by electrothermal atomic absorption spectroscopy. These data indicate that HA is an effective barrier to metal ion release, even for the thinner coatings, due to formation of metal phosphates or to incorporation of metal ions in the HA structure.
},
	keywords = {Absorption spectroscopy, Alloys, Aluminum, article, Atomic spectroscopy, balanced salt solution, Bioactive coatings, Biocompatible Materials, Biomaterials, Calcium Compounds, Dissolution, Durapatite, Electric charge, Electrochemical dissolution, Electrochemical impedance spectroscopy, electrochemistry, Electrothermal atomic absorption spectroscopy, Hank balanced salt solution, hydroxyapatite, Ion release, Ions, metal ion, Metal ion release, Metal phosphates, Microscopy, Electron, Scanning, Oxidation, Plasma spraying, potentiometry, priority journal, Spectrophotometry, Atomic, Spectroscopy, Substrates, thickness, Thickness effect, Time Factors, Titanium, Titanium alloys, vanadium},
	isbn = {01429612 (ISSN)},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0030087995\&partnerID=40\&md5=ec5e4bddc601b37b0dbe58029dd679d4},
	author = {Sousa, S.R. and Barbosa, M.A.}
}
