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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Shukla, P. P.
in Cooperation with on an Cooperation-Score of 37%
Topics
Publications (9/9 displayed)
- 2011Mathematical modelling of the fibre laser surface processing of a zirconia engineering ceramic by means of three-dimensional finite element analysiscitations
- 2011Characterization and compositional study of a ZrO2 engineering ceramic irradiated with a fibre laser beamcitations
- 2011Influence of laser beam brightness during surface treatment of a ZrO2 engineering ceramic
- 2011Distribution of temperature during fibre laser radiation and the effects on the phase transformation of ZrO2 engineering ceramiccitations
- 2011Modification of fracture toughness parameter K1c following CO2 laser surface treatment of Si3N4 engineering ceramiccitations
- 2011Evaluation of fracture toughness of ZrO2 and Si3N4 engineering ceramics following CO2 and fibre laser surface treatmentcitations
- 2011Examination of temperature distribution and the thermal effects on Si3N4 engineering ceramics during fibre laser surface treatmentcitations
- 2010Fracture toughness modification by using a fibre laser surface treatment of a silicon nitride engineering ceramiccitations
- 2010On the establishment of an appropriate method for evaluating the residual stresses after laser surface treatment of ZrO2 and Si3N4 engineering ceramics
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article
Fracture toughness modification by using a fibre laser surface treatment of a silicon nitride engineering ceramic
Abstract
Surface treatment of a silicon nitride (Si<sub>3</sub>N<sub>4</sub>) engineering ceramic with fibre laser radiation was conducted to identify changes in the fracture toughness as measured by K<sub>1c</sub>. A Vickers macro-hardness indentation method was adopted to determine the K<sub>1c</sub> of the Si<sub>3</sub>N<sub>4</sub> before and after fibre laser surface treatment. Optical and a scanning electron microscopy (SEM), a co-ordinate measuring machine and a focus variation technique were used to observe and measure the dimensions of the Vickers indentation, the resulting crack lengths, as well as the crack geometry within the as-received and fibre laser-treated Si<sub>3</sub>N<sub>4</sub>. Thereafter, computational and analytical methods were employed to determine the K<sub>1c</sub> using various empirical equations. The equation K<sub>1c</sub> = 0.016 (E/Hv)<sup>1/2</sup> (P/c<sup>3/2</sup>) produced most accurate results in generating K<sub>1c</sub> values within the range from 4 to 6 MPa m<sup>1/2</sup>. From this it was found that the indentation load, hardness, along with the resulting crack lengths in particular, were the most influential parameters within the K<sub>1c</sub> equation used. An increase in the near surface hardness of 4% was found with the Si<sub>3</sub>N<sub>4</sub> in comparison with the as-received surface, which meant that the fibre laser-treated surface of the Si<sub>3</sub>N<sub>4</sub> became harder and more brittle, indicating that the surface was more prone to cracking after the fibre laser treatment. Yet, the resulting crack lengths from the Vickers indentation tests were reduced by 37% for the Si<sub>3</sub>N<sub>4</sub> which in turn led to increase in the K<sub>1c</sub> by 47% in comparison with the as-received surface. It is postulated that the fibre laser treatment induced a compressive stress layer by gaining an increase in the dislocation movement during elevated temperatures from the fibre laser surface processing. This inherently increased the compressive stress within the Si<sub>3</sub>N<sub>4</sub> and minimized the crack propagation during the Vickers indentation test, which led to the fibre laser-radiated surface of the Si<sub>3</sub>N<sub>4</sub> engineering ceramic to have more resistance to crack propagation.