Two-phase mechanism of laser-induced removal of thin absorbing films. I. Theory

Veiko, Vadim P.; Metev, S.; Kaidanov, A. I.; Libenson, Mikhail N.; Jakovlev, E B

doi:10.1088/0022-3727/13/8/026

Cited by 50 publications

(15 citation statements)

References 6 publications

(6 reference statements)

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“…Once the plasma plume starts to (c) interface of decoated and coated sample decay, a clear sight of the particle ejection from the laser-irradiated surface was observed, as shown inside the circles in Figs 12(b)-(d). The combined effects thus served as a clear evidence of the partial coating vaporization and subsequent liquid metal expulsion, which is in agreement with reference [30]. The particles seemed to be the melted particles ejected from the irradiated spot by the vapour pressure created in the irradiated zone.…”

Section: Discussion On Removal Mechanismsupporting

confidence: 88%

Laser stripping of TiAlN coating to facilitate reuse of cutting tools

Marimuthu

Kamara

Whitehead

et al. 2011

Proceedings of the Institution of Mechanical Engineers, Part B:

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The potential of using the laser ablation process to perform controlled stripping of titanium aluminium nitrite (TiAlN) coating from tungsten carbide (WC) substrate is explored in this paper. TiAlN coatings are extensively used in cutting tools to improve machining capability, and to extend the life of the tools. However, if any error is detected on the coated tools, or when the tooling needs to be reused, it is mandatory to remove the existing coating to facilitate reshaping/recoating. The existing coating removal process uses chemical stripping methods, which are not environmentally friendly and not suitable for selective coating removal. In the present work, excimer laser removal of TiAlN from coated WC flat plates has been studied and demonstrated as a viable alternative to existing chemical stripping methods. The ablation thresholds of the TiAlN coating and WC substrate were identified as 1.85 J/cm 2 and 2.3 J/cm 2 respectively. The paper also presents experimental and theoretical evidence of the process mechanism responsible for laser stripping of TiAlN coatings

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Section: Discussion On Removal Mechanismsupporting

confidence: 88%

Laser stripping of TiAlN coating to facilitate reuse of cutting tools

Marimuthu

Kamara

Whitehead

et al. 2011

Proceedings of the Institution of Mechanical Engineers, Part B:

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“…The melt duration induced by laser melting of metal films on a substrate can last much longer than the pulse duration and has been measured on the order of 100's of nanoseconds for chromium films [10] to microseconds for gold films [9]. Expulsion of liquid from the molten pool may result from flow induced by surface-tension gradients, vapor recoil pressure, and explosive phase change [8][9][10][11][12][13][14], as shown in Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

Nanosecond Time-Resolved Measurements of Transient Hole Opening During Laser Micromachining of an Aluminum Film

Hendijanifard¹,

Willis

2013

Journal of Heat Transfer

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Laser micromachining of an aluminum film on a glass substrate is investigated using a time-resolved transmission imaging technique with nanosecond resolution. Micromachining is performed using a 7 ns pulse-width Nd:YAG laser operating at the 1064 nm wavelength for fluences ranging from 2.2 to 14.5 J/cm 2 . A nitrogen laser-pumped dye laser with a 3 ns pulse-width and 500 nm wavelength is used as a light source for visualizing the transient hole area. The dye laser is incident on the free surface and a CCD camera behind the sample captures the transmitted light. Images are taken from the back of the sample at various time delays with respect to the beginning of the ablation process, allowing the transient hole area to be measured. For low fluences, the hole opening process is delayed long after the laser pulse and there is significant scatter in the data due to weak driving forces for hole opening. However, for fluences at and above 3.5 J/cm 2 , the starting time of the process converges to a limiting minimum value of 12 ns, independent of laser fluence. At these fluences, the rate of hole opening is rapid, with the major portion of the holes opened within 25 ns. The second stage of the process is slower and lasts between 100 and 200 ns. The rapid hole opening process at high fluences can be attributed to recoil pressure from explosive phase change. Measurements of the transient shock wave position using the imaging apparatus in shadowgraph mode are used to estimate the pressure behind the shock wave. Recoil pressure estimates indicate pressure values over 90 atm at the highest fluence, which decays rapidly with time due to expansion of the ablation plume. The recoil pressure for all fluences above 3.1 J/cm 2 is higher than that required for recoil pressure driven flow due to the transition to explosive phase change above this fluence.

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“…* Solid phase explosive removal, caused by a gas pressure build-up at film-substrate interface as a result from substrate vaporization or by thermal-induced stresses. * Two-phase removal, which was characterized by partial vaporization and subsequent liquid expulsion [1][2][3][4].…”

Section: Introductionmentioning

confidence: 99%