Influence of heat accumulation during laser micromachining of CoCrMo alloy with ultrashort pulses in burst mode

Metzner, Daniel; Lickschat, Peter; Weißmantel, Steffen

doi:10.1007/s00339-019-3203-7

Cited by 20 publications

(22 citation statements)

References 23 publications

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“…Both fluences are smaller than the ablation threshold of CoCrMo [13] and thus in the non-ablation regime. Due to the high intra-burst pulse repetition rate of 80 MHz, residual heat is accumulated, which exceeds the boiling temperature in this regime after a certain number of pulses and material is removed by evaporation.…”

Section: Ablation Depthmentioning

confidence: 95%

“…The applied fluences in the range between 0.2 and 0.75 J/cm 2 per pulse in a burst were chosen to ensure that the absorbed laser radiation is smaller but also larger than the ablation threshold of the investigated materials [13,14]. Experiments at fluences per pulse above the ablation threshold are designated in this paper as "ablation regime" and the fluences below the ablation threshold as "non-ablation regime".…”

Section: Methodsmentioning

confidence: 99%

“…Due to the short intra-burst pulse repetition time of 12.5 ns, the laser-induced heat induced by each laser pulse in the interaction zone cannot completely dissipate within the material before the subsequent pulse interacts with the material surface [13,16]. As a result, heat is accumulated and the temperature in the interaction zone increases with an increase in the number of pulses in the burst.…”

Section: Burst Mode Induced Heat Accumulationmentioning

confidence: 99%

“…By using an eight-pulse burst with an intra-burst pulse repetition time of 12.5 ns, the burst has a time width of 87.5 ns. In conclusion, melting films can be formed which, depending on the number of pulses and fluence per pulse in the burst, [13] remain for a period of a few picoseconds to over 100 ns until they solidify [13,16]. The movement within the melt film is described in terms of melt convection [17,18].…”

Section: Burst Mode Induced Heat Accumulationmentioning

confidence: 99%

“…In conclusion, different surface structures caused by the dynamics of the melt film can be produced. These melting dynamics can induce a smoothing effect to obtain structured surfaces with a very low roughness [13,24,25]. In the case of a further increase of the surface temperature by accumulated heat, the boiling temperature can be exceeded even in the non-ablation regime and material can be removed by evaporation [16].…”

Section: Burst Mode Induced Heat Accumulationmentioning

confidence: 99%

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Surface treatment on cobalt and titanium alloys using picosecond laser pulses in burst mode

2020

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The authors report on the results of surface treatment experiments using a solid-state amplified laser source emitting laser pulses with a pulse duration of 10 ps. The laser source allows the generation of pulse trains (bursts) with an intra-burst pulse repetition rate of 80 MHz (pulse-to-pulse time interval about 12.5 ns) with up to eight pulses per burst. In this study a wavelength of 1064 nm was used to investigate both ablation of material and laser-induced surface modifications occuring in metallic implant alloys CoCrMo (cobalt-chromium-molybdenum) and TiAlV (titanium-aluminum-vanadium) in dependence of the number of pulses and fluences per pulse in the burst. By using the burst mode, a smoothing effect occurs in a certain parameter range, resulting in very low surface roughness of the generated microstructures. It is demonstrated that at fluences per pulse which are smaller than the material-specific ablation threshold, a self-organized pore formation takes place if a defined number of pulses per burst is used. Thus, the advantage of the MHz burst mode in terms of a possible surface modification is established.

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Section: Ablation Depthmentioning

confidence: 95%

Section: Methodsmentioning

confidence: 99%

Section: Burst Mode Induced Heat Accumulationmentioning

confidence: 99%

Section: Burst Mode Induced Heat Accumulationmentioning

confidence: 99%

Section: Burst Mode Induced Heat Accumulationmentioning

confidence: 99%

See 3 more Smart Citations

Surface treatment on cobalt and titanium alloys using picosecond laser pulses in burst mode

2020

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Process limits for percussion drilling of stainless steel with ultrashort laser pulses at high average powers

et al. 2021

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The availability of commercial ultrafast lasers reaching into the kW power level offers promising potential for high-volume manufacturing applications. Exploiting the available average power is challenging due to process limits imposed by particle shielding, ambient atmosphere breakdown, and heat accumulation effects. We experimentally confirm the validity of a simple thermal model, which can be used for the estimation of a critical heat accumulation threshold for percussion drilling of AISI 304 steel. The limits are summarized in a processing map, which provides selection criteria for process parameters and suitable lasers. The results emphasize the need for process parallelization.

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Ablation characteristics on silicon from ultrafast laser radiation containing single MHz and GHz burst pulses

et al. 2022

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The authors present results of ablation on silicon with ultrafast laser radiation featuring burst pulses using an amplified burst-mode solid-state laser, featuring an emitting wavelength of 1030 nm to generate single burst cavities on silicon. Laser parameter are varied for different pulse durations from 270 fs up to 10 ps, burst fluences, and number of sub-pulses per burst in the respective burst regime with sub-pulse repetition rates of 65 MHz and 5 GHz. The resulting ablated volume per burst and per sub-pulse in a burst as well as the topography are investigated and discussed.

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Influence of heat accumulation during laser micromachining of CoCrMo alloy with ultrashort pulses in burst mode

Cited by 20 publications

References 23 publications

Surface treatment on cobalt and titanium alloys using picosecond laser pulses in burst mode

Surface treatment on cobalt and titanium alloys using picosecond laser pulses in burst mode

Process limits for percussion drilling of stainless steel with ultrashort laser pulses at high average powers

Ablation characteristics on silicon from ultrafast laser radiation containing single MHz and GHz burst pulses

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