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Laser finishing of polycrystalline diamond as strengthening mechanism

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journal contribution
posted on 27.02.2020, 11:03 by Manuela PacellaManuela Pacella
Polycrystalline diamonds are widely used in the cutting tool industry for machining of aluminium alloy and metal matrix composites as they exhibit superior wear resistance. However, their wear characteristics are dependent on their microstructural features (i.e. percentage of binder phase and size of grains) which are defined during the sintering process. Low-energy fibre laser process of polycrystalline diamond composites with different grain dimensions is proposed to promote microstructural changes, enhance their hardness, and retain surface finish. Specimens were processed with a nanosecond pulsed fibre laser (ytterbium-doped) at a wavelength of 1064 nm. Samples treated at various fluences, beam speeds and pulse durations were characterised via 3D interferometry, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX) and microindentation hardness test. At a fluence below the composite’s ablation threshold (i.e. 20 J cm 2), the investigated finishing/polishing process for a coarse grain polycrystalline diamond resulted in a change of diamond grain size, a surface integrity of 140 nm and increased micro hardness (i.e. 240 GPa). The laser treatment caused plastic deformation of the grains, changing the intergranular boundaries area therefore impeding dislocation movements and enhancing hardness.

History

School

  • Mechanical, Electrical and Manufacturing Engineering

Published in

Procedia CIRP

Volume

87

Pages

240 - 244

Source

5th CIRP Conference on Surface Integrity (CSI 2020)

Publisher

Elsevier

Version

VoR (Version of Record)

Rights holder

© The Author

Publisher statement

This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Acceptance date

25/02/2020

Publication date

2020-05-31

Copyright date

2020

ISSN

2212-8271

Language

en

Depositor

Dr Manuela Pacella. Deposit date: 26 February 2020