Polissage et texturation de surface par fusion laser Christophe ARNAUD, Anthony ALMIRALL, Charly LOUMENA et Rainer KLING C. Arnaud et al., Journal of Laser Applications, Vol. 29, 022501 (2017)
Poste laser pour le polissage et la texturation par fusion laser Source IPG 300W - CW Scanner galvanométrique Lentille Ftheta = 254mm Dimension spot : 300µm Gaz neutre (Ar) 18/09/2017 2
Principe du polissage par fusion laser Les pics fondent pour remplir les creux. Les tensions de surface lissent le métal fondu. Aciers inoxydables Sa=2,2 µm um 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Sa=0,30µm Aluminium sablé um 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Sa= 1,8µm -> 0,18µm 18/09/2017 3
Principe de la texturation par fusion um 90 80 70 60 50 40 30 20 10 0
Exemples de texturation par fusion laser Cuir 7 s/cm² (3.9 x 3.9 cm²) Alligator 7.35 s/cm² (9.6 x 8.0 cm²) 10mm 10mm Vagues Hauteur200 µm 27 s/cm² 18/09/2017 5
Texturation par fusion laser sur acier Accéléré 4x 18/09/2017 6
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Controlling microstructure formation on stainless steel surface F. Fraggelakis (1,2), G. Mincuzzi (1), J. Lopez (1,2), I. Manek-Hönninger (2), R. Kling (1) (1) ALPhANOV, IOA, Rue F. Mitterrand 33400 Talence, France (2) Univ. Bordeaux, CNRS, CEA, CELIA UMR5107, 33405 Talence, France F. Fraggelakis et al., Optics Express, Vol. 25, No. 15 (2017)
LASER 4 FUNCTIONALIZATION APPLY LIPSS, DLIP, DLW IN metals, semiconductors, polymers, glasses & advanced materials TO FUNCTIONALIZE tribology, aesthetics and wettability SUBSTITUTE composites or applied coatings 2
Outline Introduction in surface prossesing Process key parameters Motivation State of the art in laser texturing Experimental part Induced structures for 100 khz & 1 MHz Scaling up to 2 MHz Influence of key parameters Summary 3
LIPSS generation Galvo scanners KEY-ON Fiber Femtosecond laser Tunable repetition rate 4
Main parameters Fluence (J/cm 2 ) the energy per pulse per unit surface Overlap (pps) The number of pulses delivered on a dimentionless spot in a single scan Cumulative number of pulses (pps tot ) scans (N) overlap (pps) Dose (J/cm 2 ) Fluence cumulative number of pulses 5
Main parameters Fluence (J/cm 2 ) the energy per pulse per unit surface Overlap (pps) The number First of pulse pulses delivered on a dimentionless Last pulse spot in a single scan Irradiation axis Cumulative number of pulses 4 (pps Pulses 4 tot pps Per ) Spot scans (N) overlap (pps) Irradiation axis Dose (J/cm 2 ) Fluence cumulative number of pulses 84 pps tot 6
State of the art: LIPSS with fs at 1 khz pps tot Tsibidis et al. Phys. Rev. B 92(4) (2015). Mechanisms? How to scale up? 7
Ripple formation I Polarization Axis 1) Surface Plasmon: Oscillation of Electron density along the surface 2) Surface Plasmon Polariton: Coupling of incident beam with surface Plasmon
Ripple formation II 2 nd Pulse Many Pulses Ripples are formed as a result of movement of molten material in a periodical temperature gradient G. D. Tsibidis, M. Barberoglou, P. A. Loukakos, E. Stratakis and C. Fotakis, Physical Review B 86 (11) (2012). 9
LIPSS Applications SPIKES Surface blackening Light diffraction RIPPLES Anti-friction Treated thin film stainless steel exhibiting high absorptivity (R<5%) Hydrophobicity view of stainless steel surface textured with LIPSS under different angles. Bactericidal Friction performance of rippled surface in comparison with untreated surface N. Epperlein, et al. Appl. Surf. Sci. - (2017). Subwavelength grating Side view of a 1ul water droplet on textured surface M. Faucon et al., SPIE 8972 (2014) L. Gemini et al., SPIE 10092 (2017) E. coli clearly displayed reduced adhesion on the areas structure with LIPSS J. Bonse, et al. Biomedical and Technical Applications (2015), p. Chapter 7. Diffraction of all visible spectrum by nano-ripples 10
State of the art: 1 MHz on stainless steel 1 MHz 0.8 J/cm2 Overlap Low repetition rate Kam et al. 2015. Journal of Micromechanics and Microengineering 25(4): 045007. Parameters: Fluence (Φ), cumulative number of pulses (pps tot ) High repetition rate Heat accumulation Parameters: Fluence (Φ), number of scans (N), Overlap (pps) 11
Material s temporal temperature Bauer et al. 2015. Opt. Express 23(2): 1035 43. Heat builds up when f ~ 1 MHz Temperature gradient along z becomes more intense Higher pps will result in greater T sat 12
Experimental Stainless steel 316 Value min Max Fluence 0.06 J/cm 2 0.94 J/cm 2 Overlap ~15 pps ~300 pps Scans (N) 1 1000 Repetition rate 100 khz 2 MHz 13
Surface morphology at 100 khz 100 khz 70 pps N= 1 2 5 10 20 50 14
1 MHz 70 pps Surface morphology at 1 MHz N= 1 2 5 10 20 50 15
100 khz and 1 MHz comparison 0.23 J/cm 2 70 pps 50 scans How do they emerge? Can we control their morphology? 100 khz: Non uniform nano-roughness Net of holes 1MHz: Uniform Structures Absence of nano-roughness Spike formation 2MHz: Non Uniform Nano roughness Large bump formation 16
Repetition rate influence 0.23 J/cm 2 70 pps Equivalent diameter (um) Cumulative number of pulses (pps tot ) Size saturation Cumulative number of pulses >4000 Higher repetition rate results in bigger nanostructures 2 MHz 1 MHz δ 21 um δ 14 um 17
Spike size tailoring: Role of overlap 1 MHz 0.23 J/cm 2 Equivalent diameter (um) no spikes 7500 pps tot 150 pps 50sc δ 16 um 7000 pps tot 70 pps 100 sc δ 13 um Cumulative number of pulses (pps tot ) pps tot <1400 No spike! 18
Control of spike size: Fluence effect 1 MHz 70 pps 50 scans Average equivalent diameter 3500 pps tot Spike radius increases with the fluence from 8 um to 60 um There is a spike formation threshold between 0.11 J/cm 2 and 0.16 J/cm 2 19
From ripples to spikes 1 MHz 0.23 J/cm 2 70 pps δ=12.5 um 2 MHz 0.23 J/cm 2 30 pps δ=12 um ~2 times faster 20
Spike formation 2 MHz 0.23 J/cm 2 30 pps Spike emerge and being shaped through ablation and reorganization of material 21
Conclusions It is possible to use up to 2 MHz fs lasers to structure the surface There is a Spike formation threshold Fluence 0.11-0.16 J/cm 2 Cumulative number of pulses (<1400) It is possible to tune the micro spike size using: Fluence Overlap Repetition rate 22
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