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

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Abstract

The fracture toughness property (K1C) of Si3N4 and ZrO2 engineering ceramics was investigated by means of CO2 and a fibre laser surface treatment. Near surface modifications in the hardness were investigated by employing the Vickers indentation method. Crack lengths and the crack geometry were then measured by using the optical microscopy. A co-ordinate 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 K1C. An increase in the K1C of both ceramics was found by the CO2 and the fibre laser surface treatment in comparison to the as-received surfaces. The K1C of the CO2 laser radiated surface of the Si3N4 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 Si3N4 which comprised of lowering of hardness, which in turn increased the crack resistance. The effects were not similar in ZrO2 ceramic to that of the Si3N4 as the fibre laser radiation in this case had produced an increase of 34% compared to that of the CO2 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 K1C through an induced compressive stress layer. The K1C modification of the two ceramics treated by the CO2 and the fibre laser was also believed to be influenced by the different laser wavelength and its absorption co-efficient, the beam delivery system as well as the differences in the brightness of the two lasers used.
Original languageEnglish
Pages (from-to) 229-239
Number of pages11
JournalOptics and Lasers in Engineering
Volume49
Issue number2
Early online date16 Oct 2010
DOIs
Publication statusPublished - 1 Feb 2011

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Fiber lasers
surface treatment
fracture strength
fiber lasers
Surface treatment
Fracture toughness
engineering
ceramics
evaluation
Cracks
cracks
indentation
Indentation
lasers
Laser radiation
Lasers
hardness
crack geometry
Hardness
laser beams

Bibliographical note

NOTICE: this is the author’s version of a work that was accepted for publication in Optics and Lasers in Engineering. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Optics and Lasers in Engineering, [49], [2], (2010) DOI: 10.1016/j.optlaseng.2010.09.010

© 2010, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/

Keywords

  • CO2 laser
  • Fibre laser
  • Si3N4 and ZrO2 engineering ceramics
  • Vickers indentation method
  • K1c

Cite this

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title = "Evaluation of fracture toughness of ZrO2 and Si3N4 engineering ceramics following CO2 and fibre laser surface treatment",
abstract = "The fracture toughness property (K1C) of Si3N4 and ZrO2 engineering ceramics was investigated by means of CO2 and a fibre laser surface treatment. Near surface modifications in the hardness were investigated by employing the Vickers indentation method. Crack lengths and the crack geometry were then measured by using the optical microscopy. A co-ordinate 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 K1C. An increase in the K1C of both ceramics was found by the CO2 and the fibre laser surface treatment in comparison to the as-received surfaces. The K1C of the CO2 laser radiated surface of the Si3N4 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 Si3N4 which comprised of lowering of hardness, which in turn increased the crack resistance. The effects were not similar in ZrO2 ceramic to that of the Si3N4 as the fibre laser radiation in this case had produced an increase of 34{\%} compared to that of the CO2 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 K1C through an induced compressive stress layer. The K1C modification of the two ceramics treated by the CO2 and the fibre laser was also believed to be influenced by the different laser wavelength and its absorption co-efficient, the beam delivery system as well as the differences in the brightness of the two lasers used.",
keywords = "CO2 laser, Fibre laser, Si3N4 and ZrO2 engineering ceramics, Vickers indentation method, K1c",
author = "Pratik Shukla and Jonathan Lawrence",
note = "NOTICE: this is the author’s version of a work that was accepted for publication in Optics and Lasers in Engineering. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Optics and Lasers in Engineering, [49], [2], (2010) DOI: 10.1016/j.optlaseng.2010.09.010 {\circledC} 2010, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/",
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TY - JOUR

T1 - Evaluation of fracture toughness of ZrO2 and Si3N4 engineering ceramics following CO2 and fibre laser surface treatment

AU - Shukla, Pratik

AU - Lawrence, Jonathan

N1 - NOTICE: this is the author’s version of a work that was accepted for publication in Optics and Lasers in Engineering. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Optics and Lasers in Engineering, [49], [2], (2010) DOI: 10.1016/j.optlaseng.2010.09.010 © 2010, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/

PY - 2011/2/1

Y1 - 2011/2/1

N2 - The fracture toughness property (K1C) of Si3N4 and ZrO2 engineering ceramics was investigated by means of CO2 and a fibre laser surface treatment. Near surface modifications in the hardness were investigated by employing the Vickers indentation method. Crack lengths and the crack geometry were then measured by using the optical microscopy. A co-ordinate 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 K1C. An increase in the K1C of both ceramics was found by the CO2 and the fibre laser surface treatment in comparison to the as-received surfaces. The K1C of the CO2 laser radiated surface of the Si3N4 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 Si3N4 which comprised of lowering of hardness, which in turn increased the crack resistance. The effects were not similar in ZrO2 ceramic to that of the Si3N4 as the fibre laser radiation in this case had produced an increase of 34% compared to that of the CO2 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 K1C through an induced compressive stress layer. The K1C modification of the two ceramics treated by the CO2 and the fibre laser was also believed to be influenced by the different laser wavelength and its absorption co-efficient, the beam delivery system as well as the differences in the brightness of the two lasers used.

AB - The fracture toughness property (K1C) of Si3N4 and ZrO2 engineering ceramics was investigated by means of CO2 and a fibre laser surface treatment. Near surface modifications in the hardness were investigated by employing the Vickers indentation method. Crack lengths and the crack geometry were then measured by using the optical microscopy. A co-ordinate 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 K1C. An increase in the K1C of both ceramics was found by the CO2 and the fibre laser surface treatment in comparison to the as-received surfaces. The K1C of the CO2 laser radiated surface of the Si3N4 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 Si3N4 which comprised of lowering of hardness, which in turn increased the crack resistance. The effects were not similar in ZrO2 ceramic to that of the Si3N4 as the fibre laser radiation in this case had produced an increase of 34% compared to that of the CO2 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 K1C through an induced compressive stress layer. The K1C modification of the two ceramics treated by the CO2 and the fibre laser was also believed to be influenced by the different laser wavelength and its absorption co-efficient, the beam delivery system as well as the differences in the brightness of the two lasers used.

KW - CO2 laser

KW - Fibre laser

KW - Si3N4 and ZrO2 engineering ceramics

KW - Vickers indentation method

KW - K1c

U2 - 10.1016/j.optlaseng.2010.09.010

DO - 10.1016/j.optlaseng.2010.09.010

M3 - Article

VL - 49

SP - 229

EP - 239

JO - Optics and Lasers in Engineering

JF - Optics and Lasers in Engineering

SN - 0143-8166

IS - 2

ER -