Fracture toughness modification by using a fibre laser surface treatment of a silicon nitride engineering ceramic

Shukla, Pratik; Lawrence, Jonathan

doi:10.1007/s10853-010-4743-6

Cited by 28 publications

(26 citation statements)

References 45 publications

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“…All crack lengths were observed using an optical microscopy and scanning electron microscope (SEM) by Leo-1455VP; Cambridge, England. Fracture toughness parameter KIc was determined based on the methodology in our previous publication 15 . Figure 2.…”

Section: Experimentation and Methodologymentioning

confidence: 99%

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Development in laser peening of advanced ceramics

Shukla¹,

Smith²,

Waugh³

et al. 2015

SPIE Proceedings

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Laser peening is a well-known process applicable to surface treat metals and alloys in various industrial sectors. Research in the area of laser peening of ceramics is still scarce and a complete laser-ceramic interaction is still unreported. This paper focuses on laser peening of Al2O3 ceramics employed for cutting tools, armor plating, dental and biomedical implants, with a view to elucidate the unreported work. A detailed investigation was conducted with 1064nm Nd:YAG ns pulse laser to first understand the surface effects, namely: the topography, hardness, KIc and the microstructure of Al2O3 advanced ceramics. The results showed changes in surface roughness and microstructural modification after laser peening. An increase in surface hardness was found by almost 2 folds, as the diamond footprints and its flaws sizes were considerably reduced, thus, enhancing the resistance of Al2O3 to better withstand mechanical impact. This inherently led to an enhancement in the KIc by about 42%. This is attributed to an induction of compressive residual stress and phase transformation. This work is a first-step towards the development of a 3-dimentional laser peening technique to surface treat many advanced ceramic components. This work has shown that upon tailoring the laser peening parameters may directly control ceramic topography, microstructure, hardness and the KIc. This is useful for increasing the performance of ceramics particularly for demanding applications particularly where it matters. Upon successful peening of bullet proof vests could result to higher ballistic strength and resistance against higher sonic velocity, which would not only prevent serious injuries, but could also help to save lives of soldiers on the battle fields. .

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Section: Experimentation and Methodologymentioning

confidence: 99%

“…Typically, laser beam absorption also depends on the particular wavelength applied at the material surface. Particularly for ceramics, laser in the range of 1µm wavelength and under, tends to produce sufficient absorption [14][15][16][17] . …”

Section: Laser Peening Fundamentalsmentioning

confidence: 99%

Development in laser peening of advanced ceramics

Shukla¹,

Smith²,

Waugh³

et al. 2015

SPIE Proceedings

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“…It was found by Yasnii et al [4] that the impact toughness of 15Kh13MF steel increases up to twofold after LSP with a power density ranging from 5 × 10 8 to 2 × 10 9 W · cm −2 . The mechanism of the increase of impact toughness is mainly from two aspects: residual stresses and dislocations in the hardened layer [1,[5][6][7][8][9]. Prefabricated residual compressive stress can improve the stress threshold of crack growth.…”

Section: Introductionmentioning

confidence: 99%

Impact toughness of a gradient hardened layer of Cr5Mo1V steel treated by laser shock peening

Xia

Yan

et al. 2015

Acta Mech. Sin.

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Laser shock peening (LSP) is a widely used surface treatment technique that can effectively improve the fatigue life and impact toughness of metal parts. Cr5Mo1V steel exhibits a gradient hardened layer after a LSP process. A new method is proposed to estimate the impact toughness that considers the changing mechanical properties in the gradient hardened layer. Assuming a linearly gradient distribution of impact toughness, the parameters controlling the impact toughness of the gradient hardened layer were given. The influences of laser power densities and the number of laser shots on the impact toughness were investigated. The impact toughness of the laser peened layer improves compared with an untreated specimen, and the impact toughness increases with the laser power densities and decreases with the number of laser shots. Through the fracture morphology analysis by a scanning electron microscope, we established that the Cr5Mo1V steel was fractured by the cleavage fracture mechanism combined with a few dimples. The increase in the impact toughness of the material after LSP is observed because of the decreased dimension and increased fraction of the cleavage fracture in the gradient hardened layer.

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“…However, no other investigation except the one of Shukla and Lawrence [20,21] has been done hitherto by employing a fibre laser to process engineering ceramics. Moreover, the fibre laser was selected because of its shorter wavelength radiation in comparison to the conventional lasers previously used for ceramic processing [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

“…It would be interesting to investigate further the effect of short wavelength on the surface properties of the ZrO 2 and Si 3 N 4 engineering ceramic. Moreover, Shukla and Lawrence [20][21] investigated the effects on the K 1c using a fibre laser to surface treat a ZrO 2 and Si 3 N 4 engineering ceramics which showed changes in the K 1c of the both ceramics. However, the effects of the fibre laser are different to that of the CO 2 laser due to the differing wavelength, beam conditions as well as the beam delivery system despite applying identical parameters.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of fracture toughness of ZrO2 and Si3N4 engineering ceramics following CO2 and fibre laser surface treatment

Shukla

Lawrence

2011

Optics and Lasers in Engineering

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The fracture toughness property (K 1c ) of Si 3 N 4 and ZrO 2 engineering ceramics was investigated by means of CO 2 and a fibre laser surface treatment. Near surface modifications in the hardness was investigated by employing the Vickers indentation method. Crack lengths and geometry were then measured by using the optical. A coordinate measuring machine was used to investigate the diamond indentations and to measure the lengths of the cracks. Thereafter, computational and analytical methods were employed to determine the K 1C . An increase in the K 1C of both ceramics was found by the CO 2 and the fibre laser surface treatment in comparison to the as-received surfaces. The K 1C of the CO 2 laser radiated surface of the Si 3 N 4 was over 3 % higher in comparison to that of the fibre laser treated surface. This was by softening of the near surface layer of the Si 3 N 4 which comprised of lower in hardness, which in turn increased the crack resistance. The effects were not similar with the ZrO 2 ceramic to that of the Si 3 N 4 as the fibre laser radiation in this case had produced a rise of 34% compared to that of the CO 2 laser radiation. This occurred due to propagation of lower crack resulting from the Vickers indentation test during the fibre laser surface treatment which inherently affected the end K 1C though an induced compressive stress layer. The K 1C modification of the two ceramics treated by the CO 2 and the fibre laser was also believed to be influenced by the different laser wavelength and its absorption coefficient, the beam delivery system as well as the differences in the brightness of the two lasers used.

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Fracture toughness modification by using a fibre laser surface treatment of a silicon nitride engineering ceramic

Cited by 28 publications

References 45 publications

Development in laser peening of advanced ceramics

Development in laser peening of advanced ceramics

Impact toughness of a gradient hardened layer of Cr5Mo1V steel treated by laser shock peening

Evaluation of fracture toughness of ZrO2 and Si3N4 engineering ceramics following CO2 and fibre laser surface treatment

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