High-average-power free-electron lasers: a new laser source for materials processing

Nitriding is a well known technique to improve properties of materials. The process utilizing laser contains many different processes like heat transport and melting effects, diffusion and convection, which partially determine the synthesized coatings. This review concludes the research on titanium nitride synthesis in reactive ambient and draws conclusions for the general handling of the method. Afterwards, it becomes clear which and why, transport processes limit the coating properties. IntroductionHard material systems such as titanium nitride play an important role within the field of material sciences and industrial applications. In particular wear and corrosion protection are based on such systems. Beside the classical manufacturing procedures such as PVD or CVD, the method of the direct laser synthesis in a reactive gas environment, as examined here, represents an alternative to the production of such coatings. This review discusses the synthesis of such functional coatings on the system titanium -nitrogen by different laser irradiation based on own results respectively the literature and tries to give a general overview of the physical respectively transport processes taking place. Thus, experiments from the last three decades using similar experimental setups will be compared and discussed. Due to the availability of data of investigations utilizing titanium and nitrogen, this system was taken as a general model. After a discussion of several different experimental analyses and modelling results, the treatments get parameterized. This results in large potentials for technical applications. Finally, general conditions for the synthesis of such coatings with this procedure were set up. By means of these results it is possible to achieve purposefully predefined layer characteristics. The review concludes the most important publications containing research about this process. Thus, it could be assumed to be a reference in relation to laser nitriding or -carburizing. [4] or also hybrid procedures. A further alternative and very simple method is the direct lasers synthesis. The material is placed in a reactive gas environment and will be irradiated with laser light. Due to the developing physical and chemical effects coatings are synthesized, which possess special treatment dependent characteristics. Carburizing, nitro carburizing and/or nitriding are to most common methods from this field of processes. The method of nitriding particularly assists the improvement of tribological properties of surfaces. The surface hardness gets increased, whereby the wear resistance rises. Furthermore, these coatings are usually very non-reactive, which leads to an increase in corrosion protection. In the following the method will be studied more exactly and will be explained. Quantifying of the processes gets an important aim of the work. Arising phenomena will also be modelled. To do these investigations, the model titanium nitrogen has been used. It is a well known and often used system, and has been investigated ...

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“…The functionality of the used FEL at Jefferson lab is described in [122][123]. It works with femtosecond pulses at high frequencies.…”

Section: Free Electron Laser Nitridingmentioning

confidence: 99%

Laser nitriding: investigations on the model system TiN. A review

Höche

Schaaf

2010

Heat Mass Transfer

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“…Wavelength tunability results in enhanced ablation and deposition with resonant absorption, such as in polymers, using specific resonances to control growth processes. We have demo nstrated PLD of metals such as niobium and steel 18) . We also have performed substantial work on PLD of polymers 19) .…”

Section: Applicationsmentioning

confidence: 99%

The Jefferson Lab Free Electron Laser Program

Neil¹,

Benson²,

Biallas³

et al. 2002

Jpn. J. Appl. Phys.

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A Free Electron Laser (FEL) called the IR Demo is operational as a user facility at Thomas Jefferson National Accelerator Facility in Newport News, Virginia, USA. It utilizes a 48 MeV superconducting accelerator that not only accelerates the beam but also recovers about 80% of the electron−beam power that remains after the FEL interaction. Utilizing this recirculation loop the machine has recovered cw average currents up to 5 mA, and has lased cw above 2 kW output at 3.1 microns. It is capable of output in the 1 to 6 micron range and can produce ~0.7 ps pulses in a continuous train at ~75 MHz. This pulse length has been shown to be nearly optimal for deposition of energy in materials at the surface. Upgrades under construction will extend operation beyond 10 kW average power in the near IR and produce multi-kilowatt levels of power from 0.3 to 25 microns. This talk will cover the performance measurements of this groundbreaking laser, scaling in near-term planned upgrades, and highlight some of the user activities at the facility.

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“…A recent development is the use of laser radiation to process such metals like Ti, Al or Fe [3] in reactive atmospheres. The treatment with a free electron laser (FEL) is a possibility which has been employed very rarely [4].…”

Section: Introductionmentioning

confidence: 99%

“…The FEL radiation had a wavelength of 3.1 microns, with micropulses of 0.5 ps duration and 37. 4 MHz repetition rate at a mean micropulse energy of about 20 µJ.…”

Section: Introductionmentioning

confidence: 99%