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Synthesis of functionalized HAp-surface on β-Ti alloy using ball-burnishing assisted EDC process for biomedical application

Prakash Chander, Kotecha Ketan, Pramanik Alokesh, Basak Animesh, Shankar S.

Archives of Civil and Mechanical Engineering

2022

Vol. 22, no. 4

art. no. e192, 2022

The current research develops functionalized biocompatible hydroxyapatite (HAp)-rich surface on TNTZ alloy using a novel ball-burnishing assisted electric discharge cladding (BB-EDC) has been presented. The biomechanical properties of HAp-layer, such as mechanical properties, fatigue performance, in-vitro corrosion resistance, and bioactivity, have been investigated. The results showed that EDC-modified surfaces comprised discharge craters, globules, splats structures, and high ridges of redeposited metal. However, the BB-EDC process produced a relatively flat, smooth, dense surface with an average roughness value of 0.75 µm. The HAp-cladded layer by EDC and BB-EDC process featured an irregular surface range 25–30 µm thick and compact layer ranging 5–7 µm thick, respectively. The ball burnishing subjected caused plastic deformation on the developed layer that produced fine microstructure that increased surface hardness from 2.8 to 8.7 GPa. The functional HAp-cladded layer obtained by BB-EDC exhibit excellent corrosion properties. The dense and compact layer comprised a deformed microstructure with high residual stresses that offered high resistance to crack imitation propagation, thus resulting in better fatigue performance of β-phase TNTZ alloy. Furthermore, in-vitro bioactivity results showed that BB-EDC modified exhibit anti-inflammatory surface and promoted cell growth. The findings of the current research work offer up new possibilities for biomedical, automobile and aerospace industries to utilize the potential of BB-EDC as a new surface engineering technology to develop functionalized surfaces with improved surface characteristics and mechanical properties.

A New Star-Like SurfaceTexture for Enhanced Hydrodynamic Lubrication Performance

Uddin M. S., Liu Y. W., Shankar S.

Archives of Metallurgy and Materials

2017

Vol. 62, iss. 3

1863--1869

This paper presents a numerical modelling and optimization of a new ‘star-like’ geometric texture shape with an aim to improve tribological performance. Initial studies showed that the triangle effect is the most dominant in reducing the friction. Motivated with this, a ‘star-like’ texture shape consisting of a series of triangular spikes around the centre of the texture is proposed. It is hypothesised that by increasing the triangular effect on a texture shape, the converging micro-wedge effect is expected to increase, hence increasing the film pressure and reducing the friction. Using the well-known Reynolds boundary conditions, numerical modelling of surface texturing is implemented via finite difference method. Simulation results showed that the number of apex points of the new ‘star-like’ texture has a significant effect on the film pressure and the friction coefficient. A 6-pointed texture at a texture density of 0.4 is shown to be the optimum shape. The new optimum star-like texture reduces the friction coefficient by 80%, 64.39%, 19.32% and 16.14%, as compared to ellipse, chevron, triangle and circle, respectively. This indicates the potential benefit of the proposed new shape in further enhancing the hydrodynamic lubrication performance of slider bearing contacts.