Surface engineering alumina armour ceramics with laser shock peening

P. Shukla*, S. Robertson, H. Wu, A. Telang, M. Kattoura, S. Nath, S.R. Mannava, V.K. Vasudevan, J. Lawrence

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)

Abstract

Laser shock peening (LSP) of Al2O3 armour ceramics is reported for the first-time. A 10 J, 8 ns, pulsed Nd:YAG laser with a 532 nm wavelength was employed. The hardness, KIc, fracture morphology, topography, surface residual stresses and microstructures were investigated. The results showed an increase in the surface hardness by 10% which was confirmed by a reduction in Vickers indentations size by 5%. The respective flaw sizes of the Vickers indentations were also reduced (10.5%) and inherently increased the KIc (12%). Residual stress state by X-ray diffraction method showed an average stress of − 64 MPa after LSP, whilst the untreated surface stress measured + 219 MPa. Further verification with the fluorescence method revealed surface relaxation with a maximum compressive stress of − 172 MPa induced after LSP within the Al2O3 armour ceramic. These findings are attributed to a microstructural refinement, grain size reduction and an induction of compressive stress that was relaxing the top/near surface layer (post LSP) from the pre-existing tensile stresses. Further process refinement/optimization will provide better control of the surface properties and will act as a strengthening technique to improve the performance of armour ceramics to stop bullets for a longer period of time and protect the end-users.
Original languageEnglish
Pages (from-to)523-538
Number of pages16
JournalMaterials & Design
Volume134
Early online date1 Sep 2017
DOIs
Publication statusPublished - 15 Nov 2017
Externally publishedYes

Keywords

  • LSP
  • ceramics
  • Al2O3
  • hardness
  • KIc fracture toughness
  • residual stress
  • microstructure

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