Uday Chakkingal

Groove pressing (GP) has been successfully adopted to achieve fine grain size up to 7 μm in AZ31 magnesium alloy with an initial grain size of 55 μm. The effect of microstructural evolution and surface features on wettability, corrosion resistance, bioactivity and cell adhesion were investigated with an emphasis to study the influence of deposited phases when the samples were immersed in simulated body fluid (SBF 5 ×). The role of microstructure was also evaluated without any surface treatments or coatings on the material. GPed samples exhibit improved hydrophilicity compared to the annealed sample. After immersion in SBF, specimens were characterized using scanning electron microscopy (SEM), energy dispersive X-ray (EDAX) analysis and X-ray diffraction (XRD) methods. More amount of white precipitates composed of hydroxyapatite and magnesium phosphate along with magnesium hydroxide was observed on the surfaces of groove pressed specimens as compared to the annealed specimens with an increase in immersion time in SBF. Corrosion behavior of the samples estimated using potentiodynamic polarization curves indicate good corrosion resistance for GPed samples before and after immersion in SBF. The MTT assay using rat skeletal muscle (L6) cells revealed that both the processed and unprocessed samples are nontoxic and cell adhesion was promising for GPed sample. © 2013 Elsevier B.V. All Rights Reserved.

Commercial pure titanium (cpTi) sheets have been processed by groove pressing (GP) at room temperature to refine the grains so as to improve its properties for bone implant applications. Atomic force microscopy revealed submicron/nano roughness features on the processed cpTi. The contact angle measurements show good wettability and higher surface energy when compared to unprocessed cpTi. The bioactivity of the GP samples in simulated body fluid was also found to be enhanced with the formation of a homogenous and dense globular hydroxyapatite layer. The Ca/P ratio of the apatite layer was around 1.66 as similar to the bone mineral phase. The bioactivity enhancement of GP samples has been related to the submicron grain features which results in an increase in the surface roughness and wettability. © 2009 Elsevier B.V. All rights reserved.