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Overview


Lasers are one of the most influential inventions of the twentieth century because of their extraordinary characteristics of high brightness, high directionality, high coherence, high monochromaticity, and unique spatial and temporal distributions. Material processing by laser beams has been well established as an advanced manufacturing technology.

 

A high-power laser beam can be focused to a power density up to 10-12 W/cm2. These unique features provide excellent manufacturing capabilities with high accuracy, high quality, high efficiency, non-contact processing, high controllability, and ease of automation.
Laser material processing covers a large variety of processing technologies and research areas, including...

  • laser matter interaction
  • laser surface modification (laser transformation hardening, laser remelting, laser alloying, laser cladding, laser shock peening, laser cleaning, laser texturing, and laser glazing)
  • laser welding
  • laser cutting and drilling
  • laser forming and manufacturing
  • industrial applications.

One of the process in which we are interested is the laser cladding which is a process whereby a new layer of material is deposited on a substrate by laser fusion of blown powders or pre-placed powder coatings. Multiple layers can be deposited to form shapes with complex geometry. The use of in-situ synchrotron X-ray diffraction during cladding process enables us to follow the evolution of the microstructure and phases as function of the cladding parameters like...

  • laser power density
  • beam spot size
  • traverse speed
  • power flow rate
  • laser beam absorption.
Cladding materials are had facing allows powders (Co-based, Ni-based and Fe-based plus various carbides, those of the substrates are cast iron, mild steel, alloyed steel, non-ferrous metals and son) the working principle of the laser surface treatments which involves the absorption and then heat conduction:

Laser Treatments process

Laser Treatments process

Experimental setup at ANKA

The laser system (for in-situ and ex-situ experiments):

At the Nano beamline we have a Fiber-coupled Diode Laser LDF 600-6000
VG 4L, that consists of a diode laser head (water cooled), integrated in the
laser power unit. The laser signal can travel through an optical fiber cable
of 600 μm and 5 m. A second fiber cable of 600 μm and 20 m goes to
the Nano1 experimental hutch for in-situ experiments in the diffractometer
with the synchrotron radiation. The laser unit can work in the 900-1030
nm wavelenghts rage. It has a power stability of <+-2% at a cooling water
temperature of ΔT<1 °C, the beam quality is the 66 mm mrad FWHM, the
maximun power that we can have is 6KW.
Additionally, we have a visible 600-700 nm laser pilot to align and visualize
the laser spot position.

 

Fig.2aFig.2

 

The Laser Laboratory Installation: The main components of the laser treatment
experiments

 

The chamber and the temperature control system in the laser:

Laboratory we have a Chamber to work in vacuum or in controlled
atmosphere (Ar, N2,He, etc.). We have the possibility to install the chamber
in the diffractometer for the in-situ experiments with the synchrotron
radiation in the Nano1 Hutch or work in the laser laboratory for the ex-situ
experiment. The sample is positioned inside the chamber in a motorized
goniometer for stress analysis investigation and a X-Y-translation stage to
scan the laser beam onto the sample during the cladding process. The laser
process is controlled by two color pyrometer.

 

Fig.3Fig.4

 

The chamber for the controlled atmosphere laser treatment experiments

Contact

Dr. Sondes Bauer: Sondes BauerNul7∂kit edu
Lab: +49 (0)721 608 28012