In vitro evaluation with 5SBF of alloy ASTM F75 thermally treated with wollastonite

Abstract

Samples of a cobalt-based alloy that underwent a surface treatment were evaluated. The samples, which were obtained by casting alloy ASTM F 75, were ground and polished on one side until a mirror finish was obtained. The samples were encapsulated in wollastonite (W) using uniaxial pressure, treated at 1 220 °C for 1 h and subsequently tempered in water. The characterisation of the sample indicated that part of the ceramic encapsulating material was mechanically incorporated on the metallic surface by growth of the oxide layer of the alloy. After thermal treatment, a series of specimens were submerged in a solution with 5-fold simulated body fluid (5SBF) for 3, 5 and 21 days. Characterisation by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) indicated nucleation and growth of a homogenous layer of apatite, beginning on the third day when the sample was submerged.

Keywords

cobalt-based alloy / wollastonite / 5SBF / apatite

References

[1] Miyazaki T, Kim H, Miyaji F, et al. Bonelike Apatite Formation on the Surface of Chemically Tantalum Substrates: Effect of Heat Treatment[J]. Bioceramics, 1997, 10: 827-832.

[2] Hench L, Wilson J. An Introduction to Bioceramics; Advanced Series in Ceramics[M], 1993 Florida: World Scientific.

[3] Ortiz J, Cortés D J, Escobedo J, et al. A heat Treatment Method for Obtaining Abioactive Cobalt Base Alloy[M], 2008, 1270: 1274-1278.

[4] Salinas A, Soria M, López H. The Effect of Carbon on the Mechanical Strength of Heat Treated Cast CO₂₇Cr₅Mo Alloys. Processing and Fabrication of Advanced Materials V[J]. The Minerals, Metals & Materials Society, 1996, 69: 79.

[5] Kokubo T, Kushitani H, Sakka S, et al. Solutions Able to Reproduce in Vivo Surface-Structure Changes in Bioactive Glass-Ceramic[J]. J. Biomed. Mater. Res., 1990, 721: 734.

[6] Bharati S, Sinha M, Basu D. Hidroxyapatite Coating by Biomimetic Method on Titanium Alloy Using Concentrated SBF[J]. Bull. Mater. Sci., 2005 617-621.

[7] De Aza P, Guitian F. Phase Diagram of Wollastonite-Tricalcium Phosphate[J]. J. Am. Ceram. Soc., 1995 1653-1656.

[8] Vercik L, Assis C. Apatites Coating in vitro on Titanium-influence of the Thermal Treatment[J]. Ec. Quim., 2003, 1: 12-1.

[9] Rohanizadeh R, Al-Sadeq M, LeGeos R. Preparation of Different Forms of Titanium Oxide on Titanium Surface: Effects on Apatite Deposition[J]. J. Biomed. Mater. Res., 2004, 343: 352-371.

[10] Liu X, Ding C, Chu P. Mechanism of Apatite Formation on Wollastonite Coatings in Simulated Body Fluids[J]. Biomaterials, 2004, 25: 1755-1761.