Modification of fracture toughness parameter K1c following CO2 laser surface treatment of Si3N4 engineering ceramic

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Abstract

Surface treatment of a Si3N4 engineering ceramic assisted by a CO2 laser was conducted to identify changes in the fracture toughness parameter K1c. The K1c was determined by using a Vickers macrohardness indentation method before and after the CO 2 laser surface treatment. Optical microscopy and infinite focus variation techniques were then adopted to measure the crack length and to investigate the surface morphology as well as the crack geometry within the engineering ceramic. Thereafter, computational and analytical methods were employed to calculate the K1c. Chemical analysis was further conducted to elucidate the change in composition as a result of the CO 2 laser surface irradiation. The results showed that a decrease in the near surface hardness of 7 and 44% in the resulting crack lengths was found with the Si3N4 engineering ceramic following the CO2 laser surface treatment. This inherently led to an increase in the K1c. A rise in the K1c of 64% for the Si3N4 engineering ceramics was found (under the applied conditions) in comparison to the as received surface. This occurred due to the Si3N4 engineering ceramic being oxidised and further forming a new surface layer, which was somewhat softer than that of the as received or laser unaffected surface. Compositional analysis showed that the formation of the new surface layer as a result of the CO2 laser surface treatment was found to be SiO2.

Original languageEnglish
Pages (from-to)734-741
Number of pages8
JournalSurface Engineering
Volume27
Issue number10
DOIs
Publication statusPublished - 1 Sep 2011
Externally publishedYes

Fingerprint

surface treatment
fracture strength
Surface treatment
Fracture toughness
engineering
ceramics
Lasers
lasers
Carbon Monoxide
Cracks
surface layers
crack geometry
cracks
Chemical analysis
chemical analysis
indentation
Indentation
Optical microscopy
Surface morphology
silicon nitride

Keywords

  • CO laser
  • K1c
  • Processing
  • SiN
  • SiO

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry

Cite this

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title = "Modification of fracture toughness parameter K1c following CO2 laser surface treatment of Si3N4 engineering ceramic",
abstract = "Surface treatment of a Si3N4 engineering ceramic assisted by a CO2 laser was conducted to identify changes in the fracture toughness parameter K1c. The K1c was determined by using a Vickers macrohardness indentation method before and after the CO 2 laser surface treatment. Optical microscopy and infinite focus variation techniques were then adopted to measure the crack length and to investigate the surface morphology as well as the crack geometry within the engineering ceramic. Thereafter, computational and analytical methods were employed to calculate the K1c. Chemical analysis was further conducted to elucidate the change in composition as a result of the CO 2 laser surface irradiation. The results showed that a decrease in the near surface hardness of 7 and 44{\%} in the resulting crack lengths was found with the Si3N4 engineering ceramic following the CO2 laser surface treatment. This inherently led to an increase in the K1c. A rise in the K1c of 64{\%} for the Si3N4 engineering ceramics was found (under the applied conditions) in comparison to the as received surface. This occurred due to the Si3N4 engineering ceramic being oxidised and further forming a new surface layer, which was somewhat softer than that of the as received or laser unaffected surface. Compositional analysis showed that the formation of the new surface layer as a result of the CO2 laser surface treatment was found to be SiO2.",
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author = "Shukla, {P. P.} and J. Lawrence",
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AB - Surface treatment of a Si3N4 engineering ceramic assisted by a CO2 laser was conducted to identify changes in the fracture toughness parameter K1c. The K1c was determined by using a Vickers macrohardness indentation method before and after the CO 2 laser surface treatment. Optical microscopy and infinite focus variation techniques were then adopted to measure the crack length and to investigate the surface morphology as well as the crack geometry within the engineering ceramic. Thereafter, computational and analytical methods were employed to calculate the K1c. Chemical analysis was further conducted to elucidate the change in composition as a result of the CO 2 laser surface irradiation. The results showed that a decrease in the near surface hardness of 7 and 44% in the resulting crack lengths was found with the Si3N4 engineering ceramic following the CO2 laser surface treatment. This inherently led to an increase in the K1c. A rise in the K1c of 64% for the Si3N4 engineering ceramics was found (under the applied conditions) in comparison to the as received surface. This occurred due to the Si3N4 engineering ceramic being oxidised and further forming a new surface layer, which was somewhat softer than that of the as received or laser unaffected surface. Compositional analysis showed that the formation of the new surface layer as a result of the CO2 laser surface treatment was found to be SiO2.

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