Predominant and Generic Parameters Governing the Wettability Characteristics of Selected Laser-Modified Engineering Materials

Research output: Chapter in Book/Report/Conference proceedingChapter

Abstract

Laser processing has extremely high levels of accuracy, resolution and controllability which facilitate tailored wettability characteristics modifi cation. This work has contributed to this by establishing generic relationships between the laser-modifi ed wettability characteristics through measured contact angle, θ, in terms of surface oxygen content, surface roughness and polar component of the surface energy, γP. Although surface oxygen content, surface roughness and γP are interrelated, this work isolated, to different extents, each of these three and determined the qualitative effect of each on selected laser surface treated ceramics, metals and polymers. Depending on the material studied, varying degrees of success in isolating each of the three factors were achieved. For the ceramics studied, the predominant factor influencing the wettability characteristics was increased γP. Surface oxygen content was found to effect changes to a much lesser extent and surface roughness was shown to play a very minor role. For the metals studied, the increase in surface roughness governed the modifi cation of the wettability characteristics, whilst increases in the surface oxygen content and γP were shown to play lesser roles. It was more diffi cult to isolate the effects of γP and surface oxygen content for the metals. Even so, it was possible to infer from the fi ndings that the factor playing the predominant role was generic. For the polymer studied, surface energy was found to exercise a more dominant role than either surface oxygen content or surface roughness; however, this was only the case to a certain extent as laser-induced patterning of the polymer brought about a marked increase in θ that was contrary to Wenzel's equation. The periodic nature of the laser-induced patterned surface gave rise to a liquid droplet in an equilibrium state that cannot be explained through the Wenzel and Cassie- Baxter wetting regimes. A mixed-state wetting regime is proposed to be occurring along the liquid-surface interface.

Original languageEnglish
Title of host publicationLaser Surface Modification and Adhesion
EditorsK.L. Mittal, Thomas Bahners
Place of PublicationSalem, MA
PublisherWiley
Pages289-335
Number of pages47
ISBN (Electronic)9781118831670
ISBN (Print)9781118831632
DOIs
Publication statusPublished - 13 Oct 2014
Externally publishedYes

Fingerprint

Wetting
Lasers
Oxygen
Surface roughness
Polymers
Interfacial energy
Cations
Positive ions
Metals
Cermets
Liquids
Controllability
Contact angle
Processing

Keywords

  • Ceramic
  • CO2 laser
  • Excimer laser
  • Metal
  • Polymer
  • Wettability

ASJC Scopus subject areas

  • Engineering(all)
  • Materials Science(all)

Cite this

Lawrence, J., Waugh, D., & Liang, H. (2014). Predominant and Generic Parameters Governing the Wettability Characteristics of Selected Laser-Modified Engineering Materials. In K. L. Mittal, & T. Bahners (Eds.), Laser Surface Modification and Adhesion (pp. 289-335). Salem, MA: Wiley. https://doi.org/10.1002/9781118831670.ch8

Predominant and Generic Parameters Governing the Wettability Characteristics of Selected Laser-Modified Engineering Materials. / Lawrence, Jonathan; Waugh, David; Liang, Hao.

Laser Surface Modification and Adhesion. ed. / K.L. Mittal; Thomas Bahners. Salem, MA : Wiley, 2014. p. 289-335.

Research output: Chapter in Book/Report/Conference proceedingChapter

Lawrence, Jonathan ; Waugh, David ; Liang, Hao. / Predominant and Generic Parameters Governing the Wettability Characteristics of Selected Laser-Modified Engineering Materials. Laser Surface Modification and Adhesion. editor / K.L. Mittal ; Thomas Bahners. Salem, MA : Wiley, 2014. pp. 289-335
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N2 - Laser processing has extremely high levels of accuracy, resolution and controllability which facilitate tailored wettability characteristics modifi cation. This work has contributed to this by establishing generic relationships between the laser-modifi ed wettability characteristics through measured contact angle, θ, in terms of surface oxygen content, surface roughness and polar component of the surface energy, γP. Although surface oxygen content, surface roughness and γP are interrelated, this work isolated, to different extents, each of these three and determined the qualitative effect of each on selected laser surface treated ceramics, metals and polymers. Depending on the material studied, varying degrees of success in isolating each of the three factors were achieved. For the ceramics studied, the predominant factor influencing the wettability characteristics was increased γP. Surface oxygen content was found to effect changes to a much lesser extent and surface roughness was shown to play a very minor role. For the metals studied, the increase in surface roughness governed the modifi cation of the wettability characteristics, whilst increases in the surface oxygen content and γP were shown to play lesser roles. It was more diffi cult to isolate the effects of γP and surface oxygen content for the metals. Even so, it was possible to infer from the fi ndings that the factor playing the predominant role was generic. For the polymer studied, surface energy was found to exercise a more dominant role than either surface oxygen content or surface roughness; however, this was only the case to a certain extent as laser-induced patterning of the polymer brought about a marked increase in θ that was contrary to Wenzel's equation. The periodic nature of the laser-induced patterned surface gave rise to a liquid droplet in an equilibrium state that cannot be explained through the Wenzel and Cassie- Baxter wetting regimes. A mixed-state wetting regime is proposed to be occurring along the liquid-surface interface.

AB - Laser processing has extremely high levels of accuracy, resolution and controllability which facilitate tailored wettability characteristics modifi cation. This work has contributed to this by establishing generic relationships between the laser-modifi ed wettability characteristics through measured contact angle, θ, in terms of surface oxygen content, surface roughness and polar component of the surface energy, γP. Although surface oxygen content, surface roughness and γP are interrelated, this work isolated, to different extents, each of these three and determined the qualitative effect of each on selected laser surface treated ceramics, metals and polymers. Depending on the material studied, varying degrees of success in isolating each of the three factors were achieved. For the ceramics studied, the predominant factor influencing the wettability characteristics was increased γP. Surface oxygen content was found to effect changes to a much lesser extent and surface roughness was shown to play a very minor role. For the metals studied, the increase in surface roughness governed the modifi cation of the wettability characteristics, whilst increases in the surface oxygen content and γP were shown to play lesser roles. It was more diffi cult to isolate the effects of γP and surface oxygen content for the metals. Even so, it was possible to infer from the fi ndings that the factor playing the predominant role was generic. For the polymer studied, surface energy was found to exercise a more dominant role than either surface oxygen content or surface roughness; however, this was only the case to a certain extent as laser-induced patterning of the polymer brought about a marked increase in θ that was contrary to Wenzel's equation. The periodic nature of the laser-induced patterned surface gave rise to a liquid droplet in an equilibrium state that cannot be explained through the Wenzel and Cassie- Baxter wetting regimes. A mixed-state wetting regime is proposed to be occurring along the liquid-surface interface.

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KW - Excimer laser

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