Conference Papers
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Item Burnishing of ultra high molecular weight poly ethylene(Elsevier Ltd, 2021) Ashish, V.; Prasanna Kumar Reddy, S.; Kannan, C.; Oyyaravelu, R.; Balan, A.S.S.Ultra-high molecular weight polyethylene (UHMWPE) has been a choice for knee and hip implants since a very long time due to its outstanding tribological properties. UHMWPE has many applications other than biomedical implants like hydrodynamic bearings and marine applications. The main objective of this research work is to enhance the surface properties of UHMWPE and eventually increase its life expectancy for the implants. For this purpose, the UHMWPE sheet has been milled to give it a required shape and then ball burnished with a carbide ball of 6mm diameter under two different environments viz. room and cryogenic with three different burnishing strategic patterns. A constant load of 150N is maintained by the tool on UHMWPE sample with a burnishing feed of 4000mm/min along with a step over a distance of 0.06mm after every pass for three different carefully chosen burnishing patterns. To understand the wear behaviour of the material, wear test has been performed on reciprocating wear testing machine with a stainless-steel ball as a pin for 6500 cycles in the medium of Hank's balanced salt solution (HBSS) as a lubricating agent and to maintain the pH value which is same as in the human body. The lowest average surface roughness (Ra=0.52μm) is reported for the second strategy pattern which gets burnished under the cryogenic environment. This sample also exhibited better wear resistance than other samples burnished under different environments and using different strategic patterns. © 2021 Elsevier Ltd. All rights reserved.Item Laser Surface Melting of Cold Metal Transfer Wire Arc Directed Energy Deposited AZ31 Mg Alloy(Springer Science and Business Media Deutschland GmbH, 2025) Manjhi, S.K.; Bontha, S.; Balan, A.S.S.The deposition of Mg alloy using an additive manufacturing process is challenging due to its volatile nature at high temperatures and difficult handling of Mg powder during fabrication. Therefore, the cold metal transfer wire arc additive manufacturing (CMT-WAAM) process deposits AZ31 Mg alloy because of its tremendous potential to fabricate heat-sensitive materials due to comparatively low heat input and wire as a feed material. However, the mechanical properties of CMT-WAAMed AZ31 Mg alloy are still poor due to pores, microcracks, and poor surface finish. Therefore, deposited components cannot be directly used in the application. Machining is required to make the surface smooth and flat before application. However, microcracks and burrs are the primary issues during milling operation, further reducing the mechanical properties and corrosion performance of deposited parts. Therefore, this study uses the laser surface melting (LSM) process to enhance surface properties by minimizing the microcracks and other CMT-WAAMed AZ31 Mg alloy defects. The obtained results of the 3D profilometer show that the surface roughness (Ra) of machined samples was 3.34 μm, which is reduced to 2.279 μm after laser surface melting treatment. In addition, optical microscope (OM) results exhibited a huge reduction of grain refinement after LSM from 45 ± 3 μm to less than 1 μm with dendrites microstructure. Consequently, the hardness of the surface increased from 60 ± 2 to 143 ± 10 HV due to grain refinement and the formation of secondary phase particles. The grain refinement and uniform distribution of secondary phase particles act as a barrier to Cl−1 corrosive ions, enhancing corrosion resistance after the SLM process. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2025.