Microcolumn development on titanium by multipulse laser irradiation in nitrogen

György, E.; Pino, A. Pérez del; Serra, P.; Morenza, J.L.

doi:10.1557/jmr.2003.0311

Cited by 17 publications

(14 citation statements)

References 32 publications

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“…Similar observations have been done in [70,72,74]. The development of microcolumns was observed by György et.al [79][80] at higher energies. Strong convective influences do not play a role for the surface quality, since the interaction time of some nanoseconds is too small.…”

Section: Surfaces -And Coating Morphology -Ns -Pulsessupporting

confidence: 88%

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

Höche

Schaaf

2010

Heat Mass Transfer

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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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Section: Surfaces -And Coating Morphology -Ns -Pulsessupporting

confidence: 88%

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

Höche

Schaaf

2010

Heat Mass Transfer

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“…1(a)], which precede the column growth is associated with the onset of significant target nitridation, i.e., with hydrodynamic instabilities driven by surface tension forces with positive temperature gradients of the surface tension coefficient induced by the local nitrogen concentration gradient on the target surface. 2,12 Since the rippled structure formation takes place in the absence of the laser generated plasma, it must not be influenced by the external electric field produced by the target bias.…”

Section: Discussionmentioning

confidence: 99%

“…1(b)] is attributed to non-uniform target vaporization and selective vapor recondensation on the molten columns top. 2,13 Indeed, multiple reflections of the laser light on the ripples walls lead to preferential vaporization from the valleys.…”

Section: Discussionmentioning

confidence: 99%

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Laser-Induced Growth of Titanium Nitride Microcolumns on Biased Titanium Targets

et al. 2005

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Titanium targets with a bias voltage ranging from −500 to +500 V were submitted to multipulse high repetition rate Nd:yttrium aluminum garnet (YAG; ‫ס‬ 1.064 m, ∼ 300 ns, ‫ס‬ 30 kHz) laser irradiations in nitrogen at intensity values below the single-pulse melting threshold. The morphology of the TiN structures formed under the cumulative action of the laser pulses on the surface of the unbiased and biased targets was investigated by profilometry and scanning electron microscopy. Under these irradiation conditions, a specific columnar surface microrelief developed. The height of the microcolumns reached about 10-15 m, and their diameter about 1-2 m. The development of TiN microcolumns was enhanced by the applied bias voltage. The enhancement in the negative biased samples was stronger than that in the positive biased ones.

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“…The enhanced light capture due to multiple reflections on such micropatterned silicon surfaces has led to the suggestion that they could form improved solar cells [8]. Conical spikes have been demonstrated in metals and semiconductors [8,16,17,18,19,20], polymers [21,22,23,24,25], composites [26] and ceramics [6,27,28]. The formation mechanism of ablation spikes shares common features with penitente formation.…”

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confidence: 99%

Controlled Irradiative Formation of Penitentes

Bergeron

Berger²,

Betterton

2006

Phys. Rev. Lett.

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Spike-shaped structures are produced by light-driven ablation in very different contexts. Penitentes 1-4 m high are common on Andean glaciers, where their formation changes glacier dynamics and hydrology. Laser ablation can produce cones 10-100 µm high with a variety of proposed applications in materials science. We report the first laboratory generation of centimeter-scale snow and ice penitentes. Systematically varying conditions allows identification of the essential parameters controlling the formation of ablation structures. We demonstrate that penitente initiation and coarsening requires cold temperatures, so that ablation leads to sublimation rather than melting. Once penitentes have formed, further growth of height can occur by melting. The penitentes intially appear as small structures (3 mm high) and grow by coarsening to 1-5 cm high. Our results are an important step towards understanding and controlling ablation morphologies.PACS numbers: 89.75. Kd,81.16.Rf,92.40.Rm,92.40.Sn, Penitentes 1-4 m high are found on glaciers in high mountain regions; laser ablation of materials can produce similar structures 10-100 µm high (Fig. 1). These structures are initiated by the same underlying physics: ablation caused by direct and reflected radiation. When radiation illuminates a surface, small surface depressions receive more reflected light than high points, leading to greater ablation in troughs and surface instability [1,2,3]. Penitente formation alters glacial energy balances and therefore affects local water runoff and flooding, feedback in climate dynamics, and paleo-climatic reconstruction [4,5]. In materials science, surface micropatterning via laser ablation can produce problematic surface roughness [6,7], but also has several proposed applications, including improved solar cells and electron-field emitters [8,9].Here we report the first laboratory generation of snow penitentes 1-5 cm high (Fig. 1). We characterize lab penitente formation and measure penitente coarsening. The lab setting allows controlled environmental conditions, and we can measure the evolution of lab penitentes visually in real time. Our experiments provide a model system for studying ablation morphologies.Penitentes occur on high-altitude snowfields exposed to intense sunlight, particularly in South America [10]. Expeditions studying penitentes have invoked the importance of sunlight [4,5,10,11] and cold, dry conditions (dew point below 0 o C), where melting is disfavored and ablation proceeds by sublimation [5,10]. Concentrated reflections and protection from wind increase penitente growth; higher temperature and humidity in the troughs of penitentes allows melting in the troughs [10]. This effect accelerates penitente growth, because sublimation of ice at 0 o C requires 7.8 times more energy than melting an equivalent volume, while the sublimating surface is evaporatively cooled, further lowering the surface temperature. Thus initiation of penitente growth requires a low dew point, but melting can occur during later height growth....

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Microcolumn development on titanium by multipulse laser irradiation in nitrogen

Cited by 17 publications

References 32 publications

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

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

Laser-Induced Growth of Titanium Nitride Microcolumns on Biased Titanium Targets

Controlled Irradiative Formation of Penitentes

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