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Title: Surface engineering alumina armour ceramics with laser shock peening
Authors: Shukla, Pratik P.
Robertson, Stuart
Wu, Houzheng
Telang, A.
Kattoura, M.
Nath, S.
Mannava, S.R.
Vasudevan, V.K.
Lawrence, Jonathan
Keywords: LSP
Ceramics
Al2O3
Hardness
KIc
Fracture toughness
Residual stress
Microstructure
Issue Date: 2017
Publisher: © Elsevier
Citation: SHUKLA, P.P., 2017. Surface engineering alumina armour ceramics with laser shock peening. Materials and Design, 134, pp. 523-538.
Abstract: Laser shock peening (LSP) of Al 2 O 3 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, K Ic , 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 K Ic (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 Al 2 O 3 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.
Description: This paper is closed access until 1st September 2018.
Sponsor: The leading author of this paper would like to thank the Engineering Physical Sciences Research Council (EPSRC) funded laser loan pool scheme and also the Science & Technology Facilities Council (STFC) for granting a state-of-the-art system for Laser Shock Peening applications (Grant no: EP/G03088X/1, (13250017 - NSL4)), which was made (by Litron Lasers Ltd.) and deployed for the first-time by the leading author of this paper.
Version: Accepted for publication
DOI: 10.1016/j.matdes.2017.08.066
URI: https://dspace.lboro.ac.uk/2134/26769
Publisher Link: https://doi.org/10.1016/j.matdes.2017.08.066
ISSN: 0264-1275
Appears in Collections:Closed Access (Materials)

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