The Marangoni effect on microstructure properties and morphology of laser-treated Al-Fe alloy with single track by FEM: Varying the laser beam velocity

2018 ◽  
Vol 119 ◽  
pp. 10-19 ◽  
Author(s):  
Moises Meza Pariona ◽  
André Felipe Taques ◽  
Luciano Allan Woiciechowski
Keyword(s):  
Laser Beam ◽  
Marangoni Effect ◽  
Single Track ◽  
Beam Velocity

scholarly journals Effect of Liquid Transparency on Laser-Induced Motion of Drops

2009 ◽  
Vol 131 (8) ◽  
Author(s):  
R. Shukla ◽  
K. A. Sallam
Keyword(s):  
Laser Beam ◽  
Rhodamine 6G ◽  
Marangoni Effect ◽  
Video Camera ◽  
Solid Substrate ◽  
Liquid Drops ◽  
Induced Motion ◽  
532 Nm ◽  
Rhodamine 6G Dye

An experimental investigation of the role of liquid transparency in controlling laser-induced motion of liquid drops is carried out. The study was motivated by application to manipulation of liquid drops over a solid substrate. Droplets with diameters of 1–4 mm were propelled on a hydrophobic substrate using a pulsed-laser beam (532 nm, 10 Hz, 3–12 mJ/pulse) with a 0.9 mm diameter fired parallel to the substrate. The test liquid was distilled water whose transparency was varied by adding different concentrations of Rhodamine 6G dye. Motion of the drops was observed using a video camera. Measurements include direction of motion and the distance traveled before the drops come to rest. The present results show that the direction of the motion depends on the drop transparency; opaque drops moved away from the laser beam, whereas transparent drops moved at small angles toward the laser beam. The motion of both transparent and opaque drops was dominated by thermal Marangoni effect; the motion of opaque drops was due to direct heating by the laser beam, whereas in the case of transparent drops, the laser beam was focused near the rear face of the transparent drops to form a spark that pushed the drops in the opposite direction. Energies lower than 3 mJ were incapable of moving the drops, and energies higher than 12 mJ shattered the drops instead of moving them. A phenomenological model was developed for the drop motion to explain the physics behind the phenomenon.

scholarly journals PARAMETERS OF LASER PROCESSING AND THEIR INFLUENCE ON TRIBOLOGICAL CHARACTERISTICS OF IRON-BASED COATINGS

2018 ◽  
Vol 17 (1) ◽  
pp. 56-63
Author(s):  
O. V. Diachenko ◽  
M. A. Kardapolova
Keyword(s):  
Wear Resistance ◽  
Laser Beam ◽  
Melting Rate ◽  
Solid Particles ◽  
Structural Components ◽  
Structural And Phase Transformations ◽  
Beam Velocity ◽  
Overlapping Coefficient ◽  
Molybdenum Boride ◽  
Load Increase

The paper considers improvement of physic-mechanical and operational properties of adhesive coatings after laser infusion with additional alloying В4С, ТаВ and МоВ. Influence of the laser infusion with additional alloying on structure, microhardness and wear-resistance of adhesive coatings of the Fe–Cr–B –Si system has been studied in the paper. While increasing a laser beam velocity microstructure is changed from equilibrium to quasi-eutectic. Presence of molybdenum boride and tantalum increases sensitivity of the coating to specific features of laser remelting. In both cases heat exchange conditions have been changed, a number of iron and chromium borides has been increased and due to this molybdenum and tantalum have been partially passing to free state that contributes to a disintegration of structural components. While introducing solid particles B4C into a coating they are dissolved in an iron matrix while being heated by a laser beam and under cooling they are isolated in the form of separated Fe an Cr boride inclusions. Laser infusion and alloying increase coating wear-resistance. Load increase from 30 to 70 Н improves coating wear resistance averagely by 15–26 % and wear resistance of non-alloyed coatings is improved by 26–43 %. An increase of melting rate and laser spot diameter does not exert significant influence on wear but an increase in overlapping coefficient leads to reduction of coating wear. Presence of solid particles in a coating and an increase in rate of melting by laser beam reduce coating wear resistance. Such rather complicated dependence of coating wear rate on conditions of laser melting and wearing process is due to a complex of structural and phase transformations which have contributed to formation of secondary solid inclusions and increased microhardness.

Melt Pool and Single Track Formation in Selective Laser Sintering/Selective Laser Melting

2014 ◽  
Vol 933 ◽  
pp. 196-201 ◽  
Author(s):  
Mohd Rizal Alkahari ◽  
Tatsuaki Furumoto ◽  
Takashi Ueda ◽  
Akira Hosokawa
Keyword(s):  
Laser Beam ◽  
Layer Thickness ◽  
Laser Power ◽  
Selective Laser Sintering ◽  
Single Track ◽  
Laser Melting ◽  
Consolidation Process ◽  
Melt Pool ◽  
Track Formation ◽  
Scan Speed

Selective Laser Sintering/Selective Laser Melting (SLS/SLM) is one of Additive Manufacturing (AM) processes that utilize layer by layer powder deposition technique and successive laser beam irradiation based on Computer Aided Design (CAD) data. During laser irradiation on metal powders, melt pool was formed, which then solidified to consolidated structure. Therefore, melt pool is an important behavior that affects the final quality of track formation. The study investigates the melt pool behavior through visualization of the consolidation process during the single track formation on the first layer. In order to understand the transformation process of metal powder to consolidated structure and mechanism involved, high speed camera was used to monitor the process. Yb:fiber laser beam was irradiated on metal powder at maximum power of 150W. The laser processing parameters such as laser power, scan speed and layer thickness were varied in order to investigate their influence on the consolidation process. The result shows the size of melt pool increased with laser power and decreasing with increment in scan speed. Furthermore, with the increase of layer thickness, melt pool formation was unstable with chaotic movement. Significant amount of molten powder splattering was recorded from the melt pool. At high layer thickness also, the molten powder formed spherical shaped and the solidified molten powder failed to wet with the substrate.

Study on Misalignment of Focus Position in Laser Metal Deposition Shaping Processing

2009 ◽  
Vol 16-19 ◽  
pp. 1218-1222
Author(s):  
Feng Jie Tian ◽  
Wei Jun Liu ◽  
Xiao Feng Shang ◽  
Guang Yang
Keyword(s):  
Laser Beam ◽  
Surface Quality ◽  
Metal Deposition ◽  
Thin Wall ◽  
Focus Position ◽  
Laser Metal Deposition ◽  
Single Track ◽  
Random Direction ◽  
Detecting Method

In order to investigate the effect on manufacturing quality of focus position misalignment between laser beam and powder convergence in laser metal deposition shaping (LMDS) processing, several experiments including single-track monolayer, straight thin-wall and ring thin-wall were made. The measurements and analysis on shape, size and surface quality of the experiment parts were carried out. An omnidirectional detecting method to check the misalignment of focus position was brought forward and tested. The results indicate that the misalignment of focus position directly affects the quality of shaping parts and shows the regularity, the detecting method can easily detect the focus position misalignment on random direction and angle and guide the adjustment on them.

scholarly journals Laser beam profiling: experimental study of its influence on single-track formation by selective laser melting

2015 ◽  
Vol 16 (7) ◽  
pp. 709 ◽  
Author(s):  
Ivan V. Zhirnov ◽  
Pavel A. Podrabinnik ◽  
Anna A. Okunkova ◽  
Andrey V. Gusarov
Keyword(s):  
Experimental Study ◽  
Laser Beam ◽  
Selective Laser Melting ◽  
Single Track ◽  
Laser Melting ◽  
Track Formation ◽  
Laser Beam Profiling

scholarly journals Investigation of laser heat treated Monel 400

2018 ◽  
Vol 219 ◽  
pp. 02005 ◽  
Author(s):  
Mateusz Kukliński ◽  
Aneta Bartkowska ◽  
Damian Przestacki
Keyword(s):  
Laser Beam ◽  
Heat Dissipation ◽  
Beam Power ◽  
Structural Elements ◽  
Additional Material ◽  
Beam Velocity ◽  
Laser Heat ◽  
Initial Stage ◽  
Heat Treated ◽  
Laser Beam Power

In this research, Monel metal was laser heat-treated for microstructural, microhardness and roughness investigation. The treatment is an initial stage for welding Monel without additional material for structural elements. The treatment was carried out with diode laser TruDiode 3006 which allows to reach a power of 3 kW. The material was treated with a constant laser beam power, equal to 1400 W, and four different laser beam velocities: 5, 25, 50 and 75 m/min. The distance between single laser tracks was 0,5 mm in every experimental series. It was found that laser heat treatment of Monel does not influence its hardness. The depth of melted areas is decreasing with an increasing laser beam velocity. The melted area manufactured with laser beam velocity equal to 5 m/min is about 350 μm. Increasing the laser beam velocity to 75 m/min causes depth reduction to about 100 μm. The melted areas are built with column crystals oriented in the direction of heat dissipation perpendicular to the heating direction.

Two-photon excitation microscopy in cellular biophysics

1995 ◽  
Vol 53 ◽  
pp. 62-63
Author(s):  
David W. Piston ◽  
Brian D. Bennett ◽  
Robert G. Summers
Keyword(s):  
Confocal Microscopy ◽  
Laser Beam ◽  
Duty Cycle ◽  
Excited Electronic State ◽  
Input Power ◽  
Two Photon ◽  
Simultaneous Absorption ◽  
Photon Excitation ◽  
Very High ◽  
Two Photon Excitation

Two-photon excitation microscopy (TPEM) provides attractive advantages over confocal microscopy for three-dimensionally resolved fluorescence imaging and photochemistry. Two-photon excitation arises from the simultaneous absorption of two photons in a single quantitized event whose probability is proportional to the square of the instantaneous intensity. For example, two red photons can cause the transition to an excited electronic state normally reached by absorption in the ultraviolet. In practice, two-photon excitation is made possible by the very high local instantaneous intensity provided by a combination of diffraction-limited focusing of a single laser beam in the microscope and the temporal concentration of 100 femtosecond pulses generated by a mode-locked laser. Resultant peak excitation intensities are 106 times greater than the CW intensities used in confocal microscopy, but the pulse duty cycle of 10-5 maintains the average input power on the order of 10 mW, only slightly greater than the power normally used in confocal microscopy.

The atomic-force microscope and its future in biology

1993 ◽  
Vol 51 ◽  
pp. 704-705
Author(s):  
Jean-Paul Revel
Keyword(s):  
Silicon Nitride ◽  
Laser Beam ◽  
Atomic Force Microscope ◽  
Scanning Tunneling Microscope ◽  
Point Of View ◽  
Scanning Tunneling ◽  
Close Relative ◽  
Tunneling Microscope ◽  
Atomic Force ◽  
Sharp Point

The last few years have been marked by a series of remarkable developments in microscopy. Perhaps the most amazing of these is the growth of microscopies which use devices where the place of the lens has been taken by probes, which record information about the sample and display it in a spatial from the point of view of the context. From the point of view of the biologist one of the most promising of these microscopies without lenses is the scanned force microscope, aka atomic force microscope.This instrument was invented by Binnig, Quate and Gerber and is a close relative of the scanning tunneling microscope. Today's AFMs consist of a cantilever which bears a sharp point at its end. Often this is a silicon nitride pyramid, but there are many variations, the object of which is to make the tip sharper. A laser beam is directed at the back of the cantilever and is reflected into a split, or quadrant photodiode.

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