dr inż. Tomasz Mościcki

Zakład Wytrzymałości Materiałów (ZWM)
Pracownia Technologicznych Zastosowań Laserów (PTZL)
stanowisko: główny specjalista
telefon: (+48) 22 826 12 81 wew.: 236/235
pokój: 030/034
e-mail: tmosc

Doktorat
2007-02-20Badanie właściwości fizycznych obłoku plazmowego powstającego przy spawaniu laserowym stali 
promotor -- prof. dr hab. Zygmunt Szymański, IPPT PAN
600
 
Kierownik projektów
1. Super-twarde pokrycia osadzane impulsem laserowym, Badania własne, Okres realizacji od 2013-01-31 do 2016-01-30, Finansowanie: NCN, SONATA, UMO-2012/05/D/ST8/03052

Ostatnie publikacje
1.Hoffman J., Chrzanowska J., Mościcki T., Radziejewska J., Stobinski L., Szymański Z., Plasma generated during underwater pulsed laser processing, APPLIED SURFACE SCIENCE, ISSN: 0169-4332, DOI: 10.1016/j.apsusc.2017.01.185, pp.1-6, 2017
Hoffman J., Chrzanowska J., Mościcki T., Radziejewska J., Stobinski L., Szymański Z., Plasma generated during underwater pulsed laser processing, APPLIED SURFACE SCIENCE, ISSN: 0169-4332, DOI: 10.1016/j.apsusc.2017.01.185, pp.1-6, 2017

Abstract:
The plasma induced during underwater pulsed laser ablation of graphite is studied both experimentally and theoretically. The results of the experiment show that the maximum plasma temperature of 25000 K is reached 20 ns from the beginning of the laser pulse and decreases to 6500 K after 1000 ns. The observed OH absorption band shows that the plasma plume is surrounded by the thin layer of dissociated water vapour at a temperature around 5500 K. The hydrodynamic model applied shows similar maximum plasma temperature at delay times between 14 ns and 30 ns. The calculations show also that already at 14th ns, the plasma electron density reaches 0.97·1027 m−3, which is the critical density for 1064 nm radiation. At the same time the plasma pressure is 2 GPa, which is consisted with earlier measurements of the peak pressure exerted on a target in similar conditions.

Keywords:
Underwater laser processing, Pulsed laser ablation in liquid, Laser induced plasma, Numerical modelling

35p.
2.Chrzanowska J., Kurpaska Ł., Giżyński M., Hoffman J., Szymański Z., Mościcki T., Fabrication and characterization of superhard tungsten boride layers deposited by radio frequency magnetron sputtering, CERAMICS INTERNATIONAL, ISSN: 0272-8842, DOI: 10.1016/j.ceramint.2016.04.166, Vol.42, No.10, pp.12221-12230, 2016
Chrzanowska J., Kurpaska Ł., Giżyński M., Hoffman J., Szymański Z., Mościcki T., Fabrication and characterization of superhard tungsten boride layers deposited by radio frequency magnetron sputtering, CERAMICS INTERNATIONAL, ISSN: 0272-8842, DOI: 10.1016/j.ceramint.2016.04.166, Vol.42, No.10, pp.12221-12230, 2016

Abstract:
The most promising areas of research of new super-hard materials are transition metal borides. These materials are one of the candidates for future superhard layers that will be competitive to DLC and c-BN layers. In this paper MoB-type tungsten boride (WB) layers were examined. WB layers have been deposited by radio frequency magnetron sputtering on Silicon (100), 304 stainless steel (SS 304) and Inconel 601 substrates. Measured thickness of herein prepared layers was about 1 µm, and all studied samples were dense, uniform and smooth. Surface investigation was performed by using an optical profilometer, atomic force microscopy, and scanning electron microscopy. The structure analysis was examined by using X-ray diffractometer (XRD) and transmission electron microscopy (TEM) techniques. Results from the XRD and TEM analysis showed that WB layers were dominated by (101) reflection and indicated a fine grain structure with a grain size of 20–40 nm. The effect of target sputtering power and ambient gas pressure was investigated. The hardness of WB layers deposited on silicon substrate was compared under the load from 1 mN to 5 mN. The hardness of WB layers deposited on SS 304 and Inconel was measured up to 50 mN. All layers of WB revealed excellent hardness exceeding 40 GPa.

Keywords:
Borides, Nanohardness, RF magnetron sputtering, Superhard layers, Tungsten boride

40p.
3.Maździarz M., Mościcki T., Structural, mechanical, optical, thermodynamical and phonon properties of stable ReB2 polymorphs from density functional calculations, JOURNAL OF ALLOYS AND COMPOUNDS, ISSN: 0925-8388, DOI: 10.1016/j.jallcom.2015.10.133, Vol.657, pp.878-888, 2016
Maździarz M., Mościcki T., Structural, mechanical, optical, thermodynamical and phonon properties of stable ReB2 polymorphs from density functional calculations, JOURNAL OF ALLOYS AND COMPOUNDS, ISSN: 0925-8388, DOI: 10.1016/j.jallcom.2015.10.133, Vol.657, pp.878-888, 2016

Abstract:
Three mechanically and dynamically stable polymorphs of rhenium diboride (ReB2) (space group: P63/mmc, No: 194), (space group: R-3m, No: 166) and (space group: Pmmn, No: 59) were thoroughly analysed within the framework of Density Functional Theory from the structural, mechanical, optical, thermodynamical and phonon properties point of view. The calculated hardness of rhombohedral structure suggests that it can be even harder than well known hexagonal ReB2.

Keywords:
Rhenium diboride, Phase stability, Density Functional Theory (DFT), Physical properties, Phonons

35p.
4.Maździarz M., Mościcki T., Structural, mechanical and optical properties of potentially superhard WBx polymorphs from first principles calculations, MATERIALS CHEMISTRY AND PHYSICS, ISSN: 0254-0584, DOI: 10.1016/j.matchemphys.2016.05.014, Vol.179, pp.92-102, 2016
Maździarz M., Mościcki T., Structural, mechanical and optical properties of potentially superhard WBx polymorphs from first principles calculations, MATERIALS CHEMISTRY AND PHYSICS, ISSN: 0254-0584, DOI: 10.1016/j.matchemphys.2016.05.014, Vol.179, pp.92-102, 2016

Abstract:
Five potentially superhard WBx polymorphs: hP10-P63/mmc-WB4, hP16-P63/mmc-WB3, View the MathML sourcehR24-R3¯ m-WB3, hP6-P63/mmc-WB2 and oP6-Pmmn-WB2 were thoroughly analyzed within the framework of First Principles Density Functional Theory from the structural, mechanical and optical properties point of view. None of the analyzed polymorphs have a hardness greater than 40 GPa, for the hardest one hP6-P63/mmc-WB2, Hv = 39 GPa. The most stable WBx polymorph is oP6-Pmmn-WB2 with the lowest cohesive energy Ecoh = −8.299 eV/Atom. Due to our knowledge, the optical properties of WB2 and cohesive energy of tungsten borides were presented for the first time. The best optical properties for Pulsed Laser Ablation possess hP6-P63/mmc-WB2 with the lowest reflectivity 0.343 for 355 nm laser radiation.

Keywords:
Ab initio calculations, Mechanical properties, Hardness, Optical properties

35p.
5.Mościcki T., Differences in Nanosecond Laser Ablation and Deposition of Tungsten, Boron, and WB2/B Composite due to Optical Properties, International Journal of Optics, ISSN: 1687-9384, DOI: 10.1155/2016/5438721, Vol.5438721, pp.5438721-1-13, 2016
Mościcki T., Differences in Nanosecond Laser Ablation and Deposition of Tungsten, Boron, and WB2/B Composite due to Optical Properties, International Journal of Optics, ISSN: 1687-9384, DOI: 10.1155/2016/5438721, Vol.5438721, pp.5438721-1-13, 2016

Abstract:
The first attempt to the deposition of WB3 films using nanosecond Nd:YAG laser demonstrated that deposited coatings are superhard. However, they have very high roughness. The deposited films consisted mainly of droplets. Therefore, in the present work, the explanation of this phenomenon is conducted. The interaction of Nd:YAG nanosecond laser pulse with tungsten, boron, and WB2/B target during ablation is investigated. The studies show the fundamental differences in ablation of those materials. The ablation of tungsten is thermal and occurs due to only evaporation. In the same conditions, during ablation of boron, the phase explosion and/or fragmentation due to recoil pressure is observed. The deposited films have a significant contribution of big debris with irregular shape. In the case of WB2/B composite, ablation is significantly different. The ablation seems to be the detonation in the liquid phase. The deposition mechanism is related mainly to the mechanical transport of the target material in the form of droplets, while the gaseous phase plays marginal role. The main origin of differences is optical properties of studied materials. A method estimating phase explosion occurrence based on material data such as critical temperature, thermal diffusivity, and optical properties is shown. Moreover, the effect of laser wavelength on the ablation process and the quality of the deposited films is discussed.

Keywords:
ablation mechanism, boron, critical temperature, plasma velocity, pulsed laser deposition, tungsten

6.Mościcki T., Radziejewska J., Hoffman J., Chrzanowska J., Levintant-Zayonts N., Garbiec D., Szymański Z., WB2 to WB3 phase change during reactive spark plasma sintering and pulsed laser ablation/deposition processes, CERAMICS INTERNATIONAL, ISSN: 0272-8842, DOI: 10.1016/j.ceramint.2015.03.042, Vol.41, pp.8273-8281, 2015
Mościcki T., Radziejewska J., Hoffman J., Chrzanowska J., Levintant-Zayonts N., Garbiec D., Szymański Z., WB2 to WB3 phase change during reactive spark plasma sintering and pulsed laser ablation/deposition processes, CERAMICS INTERNATIONAL, ISSN: 0272-8842, DOI: 10.1016/j.ceramint.2015.03.042, Vol.41, pp.8273-8281, 2015

Abstract:
Reactive spark plasma sintering (SPS) of WB2/WB3 ceramics from elements is studied; the sintering pressure dependence of the ratio of WB3 to WB2 in samples produced by SPS is discussed. Regardless of the sintering pressure, the obtained samples are very hard ~20 GPa. WB3 superhard films prepared by pulsed laser deposition (PLD) from selected SPS targets are presented.

WB3 coatings were prepared on Si (100) substrates using a nanosecond, Nd:YAG laser operating at a 355 nm wavelength. The phase analysis, crystallography, and orientations have been studied using X-ray diffraction (XRD). A WB2 to WB3 phase transformation from 8.2% WB3 in a sintered target to 93.3% WB3 in a deposited film was observed. Additionally, the surface of a SPS sintered WBx target after the ablation process was examined. XRD studies show that already during the laser ablation there is a significant WB2 to WB3 phase transformation. Vickers hardness of sintered samples was measured in macro- and micro-scale, and PLD films in the nanoscale.

Keywords:
Films, Tungsten borides, SPS – sintering, Pulsed laser ablation/deposition

40p.
7.Chrzanowska J., Hoffman J., Denis P., Giżyński M., Mościcki T., The effect of process parameters on rhenium diboride films deposited by PLD, SURFACE AND COATINGS TECHNOLOGY, ISSN: 0257-8972, DOI: 10.1016/j.surfcoat.2015.07.024, Vol.277, pp.15-22, 2015
Chrzanowska J., Hoffman J., Denis P., Giżyński M., Mościcki T., The effect of process parameters on rhenium diboride films deposited by PLD, SURFACE AND COATINGS TECHNOLOGY, ISSN: 0257-8972, DOI: 10.1016/j.surfcoat.2015.07.024, Vol.277, pp.15-22, 2015

Abstract:
Rhenium diboride (ReB2) thin films have been deposited by a nanosecond pulsed laser deposition method on Si (100) substrate heated to 570°C. The coatings were formed in the ablation process of SPS sintered ReB2 target. The effect of laser wavelength, energy density and postannealing on the films' properties was studied. Investigated wavelengths were 355 and 1064 nm of Nd:YAG nanosecond laser. Laser beam energy density varied from 2.1 to 6.1 J cm− 2 and from 4.1 to 9.4 J cm− 2 at 355 and 1064 nm, respectively. Layer thickness was of the order of several hundred nanometres. Deposition efficiency increases with an energy density in quasi linear way and strongly grows for shorter wavelength. The layers consist of two characteristic microstructures: a smooth basis and stick debris (typical diameters of several hundred nanometres). Lower energy density of laser beam and longer wavelength favour dominance of smooth basis and minimization of debris. The XRD analysis of all samples indicate the crystalline ReB2 with preferred (002) orientation and fine grain size of about 20 nm. Shorter wavelength and higher energy density foster stronger (002) orientation. Moreover, an annealing right after the deposition (25 min in 350°C) causes minimization of degree of orientation and decrease of hardness. The Vickers hardness of ReB2 films is at about 60 GPa and is reduced to about 40 GPa after the annealing process. Deposition efficiency and physical and chemical structures of layers produced under variety of conditions were studied and compared.

Keywords:
Ceramics ablation, Pulsed laser deposition, Rhenium diboride, ReB2 optical properties, Super-hard films, Wavelength influence

35p.
8.Mościcki T., Hoffman J., Chrzanowska J., The absorption and radiation of a tungsten plasma plume during nanosecond laser ablation, PHYSICS OF PLASMAS, ISSN: 1070-664X, DOI: 10.1063/1.4933214, Vol.22, pp.103303-1-7, 2015
Mościcki T., Hoffman J., Chrzanowska J., The absorption and radiation of a tungsten plasma plume during nanosecond laser ablation, PHYSICS OF PLASMAS, ISSN: 1070-664X, DOI: 10.1063/1.4933214, Vol.22, pp.103303-1-7, 2015

Abstract:
In this paper, the effect of absorption of the laser beam and subsequent radiation on the dynamics of a tungsten plasma plume during pulsed laser ablation is analyzed. Different laser wavelengths are taken into consideration. The absorption and emission coefficients of tungsten plasma in a pressure range of 0.1–100 MPa and temperature up to 70 000 K are presented. The shielding effects due to the absorption and radiation of plasma may have an impact on the course of ablation. The numerical model that describes the tungsten target heating and the formation of the plasma and its expansion were made for 355 nm and 1064 nm wavelengths of a Nd:YAG laser. The laser beam with a Gaussian profile was focused to a spot size of 0.055 mm2 with a power density of 1 × 109 W/cm2 (10 ns full width half maximum pulse duration). The plasma expands into air at ambient pressure of 1 mPa. The use of the shorter wavelength causes faster heating of the target, thus the higher ablation rate. The consequences of a higher ablation rate are slower expansion and smaller dimensions of the plasma plume. The higher plasma temperature in the case of 1064 nm is due to the lower density and lower plasma radiation. In the initial phase of propagation of the plasma plume, when both the temperature and pressure are very high, the dominant radiation is emission due to photo-recombination. However, for a 1064 nm laser wavelength after 100 ns of plasma expansion, the radiation of the spectral lines is up to 46.5% of the total plasma radiation and should not be neglected.

Keywords:
Plasma temperature, Tungsten, Laser ablation, Laser beams, Plasma pressure

30p.
9.Garbiec D., Jurczyk M., Levintant-Zayonts N., Mościcki T., Properties of Al–Al2O3 composites synthesized by spark plasma sintering method, ARCHIVES OF CIVIL AND MECHANICAL ENGINEERING, ISSN: 1644-9665, DOI: 10.1016/j.acme.2015.02.004, Vol.15, No.4, pp.933-939, 2015
Garbiec D., Jurczyk M., Levintant-Zayonts N., Mościcki T., Properties of Al–Al2O3 composites synthesized by spark plasma sintering method, ARCHIVES OF CIVIL AND MECHANICAL ENGINEERING, ISSN: 1644-9665, DOI: 10.1016/j.acme.2015.02.004, Vol.15, No.4, pp.933-939, 2015

Abstract:
This work presents fabrication and characterization of Al–Al2O3 composite materials with a 5%, 10%, 15% and 20% volume fraction of reinforcing phase particles. The spark plasma sintering method was applied for the purpose of fabricating these materials. The obtained Al–Al2O3 composites were characterized with an porosity from 1.27% to 5.07%. It was proven that as the content of hard ceramic particles increases in the composite, its density, hardness, and compression as well as tensile strength increase. The conducted study showed that a composite with 20% alumina content is characterized by a larger hardness (1355 MPa) and compression strength (247 MPa).

Keywords:
Spark plasma sintering, Composite material, Aluminum, Alumina

30p.
10.Hoffman J., Chrzanowska J., Kucharski S., Mościcki T., Mihailescu I.N., Ristoscu C., Szymański Z., The effect of laser wavelength on the ablation rate of carbon, APPLIED PHYSICS A-MATERIALS SCIENCE AND PROCESSING, ISSN: 0947-8396, DOI: 10.1007/s00339-014-8506-0, Vol.117, pp.395-400, 2014
Hoffman J., Chrzanowska J., Kucharski S., Mościcki T., Mihailescu I.N., Ristoscu C., Szymański Z., The effect of laser wavelength on the ablation rate of carbon, APPLIED PHYSICS A-MATERIALS SCIENCE AND PROCESSING, ISSN: 0947-8396, DOI: 10.1007/s00339-014-8506-0, Vol.117, pp.395-400, 2014

Abstract:
The ablation of graphite is studied as a function of laser fluence for 355, 532 and 1,064 nm wavelength generated by a nanosecond Nd:YAG laser. It has been found that in the case of lower wavelengths, the transition from the thermal ablation to the phase explosion takes place at lower laser fluences. The change of crater shape due to the effect of deep drilling in the proximity of the phase explosion threshold was observed. The calculations of plasma radiation flux to the target surface were made, and the considerable increase of absorbed energy density was found in the case of 355 nm wavelength.

Keywords:
laser ablation, ablation rate, carbon

30p.
11.Mościcki T., Expansion of laser-ablated two-component plume with disparate masses, PHYSICA SCRIPTA, ISSN: 0031-8949, DOI: 10.1088/0031-8949/2014/T161/014024, Vol.T161, pp.014024-1-4, 2014
Mościcki T., Expansion of laser-ablated two-component plume with disparate masses, PHYSICA SCRIPTA, ISSN: 0031-8949, DOI: 10.1088/0031-8949/2014/T161/014024, Vol.T161, pp.014024-1-4, 2014

Abstract:
Laser ablation of boron and tungsten is studied theoretically. The effect of disparate masses of boron and tungsten on parameters of the laser-ablated plasma plume is studied. A theoretical model is applied, which describes both the target heating and formation of the plasma and its expansion. Calculations are made for the third harmonic of a nanosecond Nd:YAG laser. The calculated distributions of plasma temperature, velocity and electron density in the early phase of expansion show that the plasma temperature is higher in the case of heavier tungsten, but the velocity is higher in the case of lighter boron, which is in agreement with experimental findings. In addition, the absorption coefficient of 355 nm radiation, the emission coefficient, the mass density and heat capacity of boron and tungsten plasma are compared.

Keywords:
laser ablation, tungsten plasma properties, boron plasma properties, superhard borides

25p.
12.Mościcki T., Hoffman J., Szymański Z., The effect of laser wavelength on laser-induced carbon plasma, JOURNAL OF APPLIED PHYSICS, ISSN: 0021-8979, DOI: 10.1063/1.4819892, Vol.114, pp.083306-1-6, 2013
Mościcki T., Hoffman J., Szymański Z., The effect of laser wavelength on laser-induced carbon plasma, JOURNAL OF APPLIED PHYSICS, ISSN: 0021-8979, DOI: 10.1063/1.4819892, Vol.114, pp.083306-1-6, 2013

Abstract:
The effect of laser wavelength on parameters of laser-ablated carbon plume is studied. A theoretical model is applied, which describes the target heating and formation of the plasma and its expansion, and calculations are made for the fundamental and third harmonic of a Nd:YAG laser. The calculated distributions of plasma temperature and electron density in the early phase of expansion show that plasma temperatures are higher in the case of 1064 nm but the electron densities are higher in the case of 355 nm, which is in agreement with experimental findings. It has been shown that while a higher plasma temperature in the case of 1064 nm is the result of stronger plasma absorption, the greater ablation rate in the case of 355 nm results in larger mass density of the ablated plume and hence, in higher electron densities. An additional consequence of a higher ablation rate is slower expansion and smaller dimensions of the plume.

Keywords:
Plasma temperature, Laser ablation, Laser beams, Absorption coefficient, Carbon

35p.
13.Mościcki T., Radziejewska J., Numerical simulation and experimental analysis of simultaneous melting and burnishing of 304 stainless steel with oscillatory laser heat source, KOVOVE MATERIALY-METALLIC MATERIALS, ISSN: 0023-432X, Vol.51, pp.37-44, 2013
Mościcki T., Radziejewska J., Numerical simulation and experimental analysis of simultaneous melting and burnishing of 304 stainless steel with oscillatory laser heat source, KOVOVE MATERIALY-METALLIC MATERIALS, ISSN: 0023-432X, Vol.51, pp.37-44, 2013

Abstract:
In this paper the simultaneous laser melting and burnishing of a stainless steel is studied both experimentally and theoretically. A continuous CO2 laser beam is moving either along a straight line or criss-crossing it. It has been shown that the oscillatory movement of the laser source together with the burnishing results in a better surface topography comparing to the non-oscillatory process. A theoretical modelling is applied to calculate the temperature field during the process. Theresults oftheoretical analysis are verifiedbyanalyzing microstructure changes of the material in laser heated zone. It has been found that a very good agreement between theoretical and experimental results is achieved when the change of the absorptivity of the laser beam with the temperature of the melted zone is taken into account.

Keywords:
laser treatment, hybridtreatment, surface structure, mathematical modelling

20p.
14.Hoffman J., Mościcki T., Szymański Z., Acceleration and distribution of laser-ablated carbon ions near the target surface, JOURNAL OF PHYSICS D-APPLIED PHYSICS, ISSN: 0022-3727, DOI: 10.1088/0022-3727/45/2/025201, Vol.45, No.2, pp.025201-1-8, 2012
Hoffman J., Mościcki T., Szymański Z., Acceleration and distribution of laser-ablated carbon ions near the target surface, JOURNAL OF PHYSICS D-APPLIED PHYSICS, ISSN: 0022-3727, DOI: 10.1088/0022-3727/45/2/025201, Vol.45, No.2, pp.025201-1-8, 2012

Abstract:
The plasma plume induced during laser ablation of graphite is studied both experimentally and theoretically. The hydrodynamic model applied shows that the high velocities of the plume observed in the experiment result from the large pressure gradient built up during laser–plume interaction. This means that at a low laser intensity of ∼109 W cm−2 the acceleration mechanism is rather gasdynamical than electrostatic. The calculated temporal profiles of plasma temperature and electron density in the early phase of expansion are in reasonable agreement with experimental profiles obtained from emission spectroscopy. The effect of evolution of the plasma temperature on time-of-flight signals is presented. It has been shown that the appearance of ions with higher charge prior to ions with lower charge often ascribed to the effect of the induced electric field can be explained by the evolution of the plume temperature.

Keywords:
carbon, laser ablation, plasma plume acceleration, hydrodynamic model

35p.
15.Mościcki T., Hoffman J., Szymański Z., Laser ablated carbon plume: experiment and modelling, NUKLEONIKA. INTERNATIONAL JOURNAL OF NUCLEAR RESEARCH, ISSN: 0029-5922, Vol.57, No.2, pp.283-286, 2012
Mościcki T., Hoffman J., Szymański Z., Laser ablated carbon plume: experiment and modelling, NUKLEONIKA. INTERNATIONAL JOURNAL OF NUCLEAR RESEARCH, ISSN: 0029-5922, Vol.57, No.2, pp.283-286, 2012

Abstract:
Laser ablation of graphite is studied both theoretically and experimentally. Plasma temperature and electron density in the early phase of expansion into vacuum are measured as a function of distance from the target. The experimental results agree well with the theoretical simulations. The simulation of ablation shows that plasma plume considerably affects the ablation rate

Keywords:
laser ablation, plasma plume

15p.
16.Hoffman J., Mościcki T., Szymański Z., The effect of laser wavelength on heating of ablated carbon plume, APPLIED PHYSICS A-MATERIALS SCIENCE AND PROCESSING, ISSN: 0947-8396, DOI: 10.1063/1.4819892, Vol.104, pp.815-819, 2011
Hoffman J., Mościcki T., Szymański Z., The effect of laser wavelength on heating of ablated carbon plume, APPLIED PHYSICS A-MATERIALS SCIENCE AND PROCESSING, ISSN: 0947-8396, DOI: 10.1063/1.4819892, Vol.104, pp.815-819, 2011

Abstract:
The effect of laser wavelength on heating of the ablated carbon plume is studied. The plasma absorption coefficients are calculated in order to analyze the results and an experiment is conducted using the first, second, and third harmonic of a Nd:YAG laser. Plasma temperature and electron density in the early phase of expansion in vacuum are studied as a function of distance from the target. The calculations show that the ratio between absorption coefficients for 1064, 532, and 355 nm is approximately 9:2:1. The experimental results do not agree well with the theoretical predictions. Indeed, the plasma temperatures are highest in the case of 1064 nm but no clear differences between 532 nm and 355 nm have been found.

Keywords:
plasma plume absorption, PLD, carbon, laser wavelength dependence

30p.
17.Mościcki T., Hoffman J., Szymański Z., Modelling of plasma formation during nanosecond laser ablation, ARCHIVES OF MECHANICS, ISSN: 0373-2029, Vol.63, pp.99-116, 2011
Mościcki T., Hoffman J., Szymański Z., Modelling of plasma formation during nanosecond laser ablation, ARCHIVES OF MECHANICS, ISSN: 0373-2029, Vol.63, pp.99-116, 2011

Abstract:
The interaction of laser beam with a target and next with the evaporated material is studied theoretically. In the case of a nanosecond laser pulse with 1064 nm wavelength, the ablation is thermal and therefore the interaction of the laser beam with a target is studied with the use of thermal model. The model which describes both the target heating, formation of the plasma and its expansion consists of equations of conservation of mass, momentum and energy and is solved with the use of Fluent software package. The calculations show a sharp increase of the plume temperature and pressure after plasma formation and following it, a considerable increase of the velocity of plasma plume. Maximum plasma pressure of 2 × 108 Pa, temperature of 61 500 K and front velocity of 3.8 × 104 m · s−1 have been found. The results show that the Mie absorption cannot be neglected in the phase of plasma formation. The shape of the plume and plasma front velocity obtained from the model are close to that observed in the experiment carried out in similar conditions.

Keywords:
laser ablation, plasma formation, plasma expansion

20p.
18.Jedyński M., Hoffman J., Mościcki T., Mróz W., Burdyńska S., Diduszko R., Kołodziejczak P., Szymański Z., Deposition of thin hydroxyapatite films by 335 nm Nd:YAG laser ablation, MATERIALS SCIENCE-POLAND, ISSN: 2083-1331, Vol.28, No.3, pp.693-702, 2010
Jedyński M., Hoffman J., Mościcki T., Mróz W., Burdyńska S., Diduszko R., Kołodziejczak P., Szymański Z., Deposition of thin hydroxyapatite films by 335 nm Nd:YAG laser ablation, MATERIALS SCIENCE-POLAND, ISSN: 2083-1331, Vol.28, No.3, pp.693-702, 2010

Abstract:
The characteristics of hydroxyapatite (Ca10(PO4)6(OH)2) thin films deposited by the pulsed laser deposition technique have been describrd. The laser used was a Nd:YAG, operating at the wavelength of 355 nm. All films were deposited at room temperature, either in ambient water vapour or in vacuum, and were annealed, after deposition in air, at 600 °C. Next, they were examined with the use of an X-ray diffractometer, Fourier transform infrared spectrometer, atomic force microscope, micro scratch tester and scanning electron microscope. The analyses showed that crystalline films exhibiting very strong
adhesion to the substrate have been obtained.

Keywords:
pulsed laser deposition, hydroxyapatite, biomaterials

20p.
19.Mościcki T., Hoffman J., Szymański Z., Net emission coefficients of low temperature thermal iron-helium plasma, OPTICA APPLICATA, ISSN: 0078-5466, Vol.38, pp.365-373, 2008
Mościcki T., Hoffman J., Szymański Z., Net emission coefficients of low temperature thermal iron-helium plasma, OPTICA APPLICATA, ISSN: 0078-5466, Vol.38, pp.365-373, 2008

Abstract:
Net emission coefficients of low temperature thermal iron-helium plasma mixture at atmospheric pressure are presented. The calculations are made assuming the plasma is in the local thermodynamic equilibrium at a pressure of 0.1 MPa. The results are presented for several values of helium mass fraction in the mixture (between 0 and 1), for a temperature range 3000–25000 K and three characteristic plasma dimensions; 0 – corresponding to the optically thin case, and 1 mm and 10 mm. The values of net emission coefficients allow the estimations of total radiation losses in iron-helium plasmas.

Keywords:
net emission coefficients, iron-helium plasma

13p.
20.Mościcki T., Hoffman J., Szymański Z., Modelling of plasma plume induced during laser welding, JOURNAL OF PHYSICS D-APPLIED PHYSICS, ISSN: 0022-3727, Vol.39, No.4, pp.685-692, 2006
Mościcki T., Hoffman J., Szymański Z., Modelling of plasma plume induced during laser welding, JOURNAL OF PHYSICS D-APPLIED PHYSICS, ISSN: 0022-3727, Vol.39, No.4, pp.685-692, 2006

Abstract:
A theoretical modelling of the plasma plume induced during welding of iron sheets with CO2 laser is presented. The set of equations consists of the equations of conservation of mass, energy, momentum and the diffusion equation and is solved with the use of the commercially available program Fluent 6.1. The computations are made for a laser power of 1700 W and for two shielding gases—argon and helium. The results show a significant difference between these two cases. When helium is used as the shielding gas, the plasma is much smaller and burns only where the metal vapour is slightly diluted by helium. In the case when argon is the shielding gas, there are actually two plasmas: argon plasma and metal plasma. The flowfield shows that the velocity increases in the hot region but only part of the mass flux enters the plasma core. In the case when argon is used as the shielding gas, the total absorption of the laser radiation amounts to 18–33% of the laser power depending on argon and iron vapour velocities. In the case of helium the total absorption is much lower and amounts to ~5% of the laser power.

Keywords:
laser welding, CFD, numerical model

32p.
21.Hoffman J., Mościcki T., Szymański Z., Modelling of time dependent plasma plume induced during laser welding, CZECHOSLOVAK JOURNAL OF PHYSICS, ISSN: 0011-4626, Vol.56, pp.B938-B943, 2006
Hoffman J., Mościcki T., Szymański Z., Modelling of time dependent plasma plume induced during laser welding, CZECHOSLOVAK JOURNAL OF PHYSICS, ISSN: 0011-4626, Vol.56, pp.B938-B943, 2006

Abstract:
Theoretical modelling of the plasma plume induced during welding of iron sheets with CO2 laser are presented. The set of equations consists of equation of conservation of mass,energy, momentum and the diffusion equation and is solved with the use of commercially available program Fluent 6.1. The computations are made for the laser power of 1700 W and shielding gas argon. Two solutions are taken into account stationary and non–stationary. The results show significant difference between these two cases.

Keywords:
laser welding, simulations, plasma

13p.
22.Mościcki T., Hoffman J., Szymański Z., Emission coefficients of low temperature thermal iron plasma, CZECHOSLOVAK JOURNAL OF PHYSICS, ISSN: 0011-4626, Vol.54, pp.C677-C682, 2004
Mościcki T., Hoffman J., Szymański Z., Emission coefficients of low temperature thermal iron plasma, CZECHOSLOVAK JOURNAL OF PHYSICS, ISSN: 0011-4626, Vol.54, pp.C677-C682, 2004

Abstract:
Iron plasma appears during material processing with laser, electric arc etc., and has considerable influence on the processing conditions. In this paper emission coefficients of low temperature thermal iron plasma at atmospheric pressure are presented. Net emission coefficients εN have been calculated for pure iron plasma as well as for Fe–Ar and Fe–He plasma mixtures. To calculate the recombination radiation the knowledge of the Biberman factors ξz fb(Te, λ) is necessary and they have been calculated from the iron photo–ionization cross sections. The calculations allow estimation of energy losses, energy radiated by plasma plume and its comparison with the energy absorbed from laser beam.

Keywords:
absorption coefficient, plasma emission, Biberman factor

13p.
23.Mościcki T., Hoffman J., Szymański Z., Dynamics of the plasma plume induced during laser welding, OPTICA APPLICATA, ISSN: 0078-5466, Vol.33, No.2-3, pp.433-443, 2003
Mościcki T., Hoffman J., Szymański Z., Dynamics of the plasma plume induced during laser welding, OPTICA APPLICATA, ISSN: 0078-5466, Vol.33, No.2-3, pp.433-443, 2003

Abstract:
The dynamics of the plasma plume produced during laserwelding is quite complex. The keyhole wall oscillates and this results in oscillations of the plasma plume over the keyhole mouth. The metal vapour, which appears in irregular bursts, interacts with the shielding gas flowing from the opposite direction. In the present work, temporary electron densities and temperatures are determined in the peaks of plasma bursts during welding with a continuous wave CO2 laser. It has been found that during strong bursts the plasma plume over the keyhole consists of metal vapour only, without being diluted by the shielding gas. The results, together with the analysis of the colour pictures from sreak camera, allow interpretation of the dynamics of the plasma plume. No apparent mixing of metal vapour and the shielding gas has been observed. In typical bursts the electron density determined from the Stark broadening of Ar I lines varies from 0.9x1023 m-3 near the metal surface to 0.5x1023 m-3 at a distance of 1.5 mm from the surface. Assuming that argon is not mixed with the metal vapour and is in local thermal equilibrium these electron densities correspond to temperatures 12.7 kK and 11.5 kK, respectively. In strong bursts the electron density varies, along the same distance, from 1.6x1023 m-3 to 0.6x1023 m-3 , which corresponds to the temperatures of 14.2 kK, respectively.

Keywords:
laser welding, plasma diagnostics

13p.
24.Kalita W., Kołodziejczak P., Hoffman J., Mościcki T., Szymański Z., Spawanie stopu magnezu AM20 laserem CO2, PRZEGLĄD MECHANICZNY, ISSN: 0033-2259, Vol.7-8, pp.48-51, 20039p.

Lista rozdziałów w ostatnich monografiach
1.
519
Banak R., Mościcki T., Tofil S., Antoszewski B., Wybrane Problemy w Mechatronice i Inżynierii Materiałowej, MONOGRAFIE, STUDIA, ROZPRAWY, rozdział: Wpływ parametrów spawania laserowego na właściwości złącza Ni-Pt w świecach zapłonowych w silnikach na biopaliwo, Politechnika Świętokrzyska, Kielce, pp.22-33, 2016
2.
462
Banak R., Zowczak W., Mościcki T., Monografie, Studia, Rozprawy, rozdział: Symulacja numeryczna kształtu jeziorka spawalniczego w trakcie procesu spawania laserowego stali 304, Politechnika Świętokrzyska, Kielce, pp.193-203, 2015

Prace konferencyjne
1.Banak R., Mościcki T., Zowczak W., Modelowanie procesu przewodnościowego spawania laserowego z wykorzystaniem oprogramowania CFD, IV SYMPOZJUM KATEDR I ZAKŁADÓW SPAWALNICTWA pt. Nowoczesne zastosowania technologii spawalniczych, 2015-06-16/06-17, Istebna (PL), pp.4-8, 2015
2.Banak R., Mościcki T., Antoszewski B., Wpływ parametrów spawania laserowego na właściwości złącza NI-PT w świecach zapłonowych dla silników na biopaliwo, IX Konferencja Naukowo-Techniczna TEROTECHNOLOGIA, 2015-10-15/10-16, Kielce (PL), pp.1-8, 2015
Banak R., Mościcki T., Antoszewski B., Wpływ parametrów spawania laserowego na właściwości złącza NI-PT w świecach zapłonowych dla silników na biopaliwo, IX Konferencja Naukowo-Techniczna TEROTECHNOLOGIA, 2015-10-15/10-16, Kielce (PL), pp.1-8, 2015

Abstract:
W pracy został przedstawiony model teoretyczny oddziaływania wiązki laserowej z materiałami różnoimiennymi w procesie spawania. W celu wyznaczenia rozkładu pola temperatur, wymiarów spoiny oraz strefy mieszania się materiałów zbudowano trójwymiarowy, niestacjonarny model numeryczny uwzględniający proces wymiany ciepła i masy. Model został wykorzystany do zbadania przebiegu i optymalizacji parametrów procesu spawania niklowo - platynowych nakładek na świece zapłonowe dla silników na biopaliwo. Zbadano pływ czasu trwania impulsu, średnicy plamki oraz kąta nachylenia wiązki na rozkład pola temperatury. Kształt strefy przetopionej otrzymany z modelu teoretycznego jest w dobrej zgodności z wynikami eksperymentalnymi

3.Banak R., Zowczak W., Mościcki T., Theoretical Model of the Laser Welding Process, TRANSCOM 2015, 11th European Conference of Young Researchers and Scientists, 2015-06-22/06-24, Žilina (SK), pp.13-18, 2015
Banak R., Zowczak W., Mościcki T., Theoretical Model of the Laser Welding Process, TRANSCOM 2015, 11th European Conference of Young Researchers and Scientists, 2015-06-22/06-24, Žilina (SK), pp.13-18, 2015

Abstract:
To determine the distribution of the temperature field and shape of the melting zone during the laser welding process of 304 stainless steel a three-dimensional numerical model was bilt and numerical simulation was performed. In order to improve the accuracy of the calculations temperature dependent material properties, heat loosdue to vaporization and heat exchange with surrounding medium due to the convection and radiation was considered.

Keywords:
Theoretical Model, Laser Welding, CFD


Abstrakty konferencyjne
1.Mościcki T., Hoffman J., Szymański Z., Modelling of the nanosecond laser ablation with the use of Ansys-Fluent, LPPM3, XIV INTERNATIONAL SEMINAR “MATHEMATICAL MODELS & MODELING IN LASER-PLASMA PROCESSES & ADVANCED SCIENCE TECHNOLOGIES, 2016-07-04/07-09, Moscow (RU), pp.58, 2016
2.Chrzanowska J., Denis P., Mościcki T., Hoffman J., Garbiec D., Frąś L., Szymański Z., Characterization of tungsten boride layers deposited in pulsed laser ablation process, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P257, pp.1-2, 2016
Chrzanowska J., Denis P., Mościcki T., Hoffman J., Garbiec D., Frąś L., Szymański Z., Characterization of tungsten boride layers deposited in pulsed laser ablation process, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P257, pp.1-2, 2016

Abstract:
Tungsten boride compounds are very promising new hard and super - hard materials. This kind of materials could be used in production of high-speed tools, durable bearings and nonabrasive surfaces. The hardness of tungsten borides strongly depends on boron content as well as material microstructure. For example hardness of W2B is about 12.4 GPa, WB hardness is 18 – 36 GPa, WB2 hardness is 28.5–39.7 GPa and WB3 hardness is 28.6 – 36.9 GPa. Moreover production of tungsten borides in the form of layers or nano -grained structured increase its hardness even above 40 GPa. Although the properties of tungsten boride structures are known from theoretical calculations, the data concerning structures produced experimentally are scare. Therefore, the properties of tungsten boride layers deposited by pulsed laser deposition (PLD) process are investigated in this paper. Layers were deposited using two types of targets: with boron to tungsten ratio of 2.5:1 and 4.5:1 and with the use of two laser wavelengths: 355 and 1064 nm.

Keywords:
pulsed laser deposition, tungsten borides

3.Mościcki T., Chrzanowska J., Hydrodynamic Model of Nanosecond Laser Ablation of Tungsten and Boron, 16th International Conference on Fluid Flow Technologies, 2015-09-01/09-04, Budapeszt (HU), pp.#27-1-8, 2015
Mościcki T., Chrzanowska J., Hydrodynamic Model of Nanosecond Laser Ablation of Tungsten and Boron, 16th International Conference on Fluid Flow Technologies, 2015-09-01/09-04, Budapeszt (HU), pp.#27-1-8, 2015

Abstract:
In this paper the interaction of Nd - YAG nanosecond laser pulse with tungsten or boron target and lasma induced during ablation are studied theoretically. Tungsten and boron were chosen because of the significant differences in their chemical and physical properties. Both materials are of a great practical importance. The model consists of equations of conservation of mass, momentum and energy and is solved with the use of commercially available program Ansys - Fluent. The calculations show the fundamental differences in ablation of both specie s. In case of tungsten the material evaporation is controlled by the plasma formation and consequently the absorption coefficient. The dense plasma plume can block laser radiation and limit energy transfer from the laser beam to the material. In case of bo ron the explosive ablation is observed. The calculations also show the sharp increase of the plume pressure after plasma formation and resulting significant increase of the velocity of plasma plume. The lume velocity obtained from the model is close to th at observed in the experiment carried out in similar conditions. Moreover, the effect of laser wavelength on the quality of the deposited boron and tungsten films has been discussed on the base of ablation model.

Keywords:
ablation mechanism, boron, critical temperature, plasma velocity, pulsed laser deposition, tungsten

4.Chrzanowska J., Mościcki T., Hoffman J., Garbiec D., Radiofrequency assisted pulsed laser deposition of WBN and ReBN thin films, EUROMAT 2015, European Congress and Exhibition on Advanced Materials and Processes, 2015-09-20/09-24, Warszawa (PL), pp.1-2, 2015
Chrzanowska J., Mościcki T., Hoffman J., Garbiec D., Radiofrequency assisted pulsed laser deposition of WBN and ReBN thin films, EUROMAT 2015, European Congress and Exhibition on Advanced Materials and Processes, 2015-09-20/09-24, Warszawa (PL), pp.1-2, 2015

Keywords:
pulsed laser deposition

5.Słowicka A., Walenta Z., Szymański Z., Hoffman J., Mościcki T., Structure and expansion of a plume emitted during laser ablation of multi-component materials, ISSW30, 30th International Symposium on Shock Waves, 2015-07-19/07-24, Tel-Aviv (IL), pp.562-571, 2015
Słowicka A., Walenta Z., Szymański Z., Hoffman J., Mościcki T., Structure and expansion of a plume emitted during laser ablation of multi-component materials, ISSW30, 30th International Symposium on Shock Waves, 2015-07-19/07-24, Tel-Aviv (IL), pp.562-571, 2015

Abstract:
Pulsed laser deposition is a method frequently used for creating thin films of various materials on
solid substrates. High energy laser pulse causes evaporation of the target material, forming a
plume which subsequently
expands and moves with high speed from the target. Thin film of the
evaporated material is deposited on the substrate placed at some distance in front of the target.
The behavior of the plume influences both the stoichiometry and homogeneity of the deposit
ed
layer

the final product of the process. Better understanding of the process of expansion of the
plume, variation of its structure as well as deposition of the material itself is therefore very
important and should give us opportunity for better contro
l of formation of the deposited layer.

Keywords:
laser ablation, plume expansion, DSMC

6.Hoffman J., Chrzanowska J., Mościcki T., Comparison of WB2.5 thin films deposited by pulsed laser deposition and magnetron sputtering, ITFPC'2015, 7th International Conference on Innovations in Thin Film Processing and Characterization, 2015-11-16/11-20, Nancy (FR), pp.94, 2015
Hoffman J., Chrzanowska J., Mościcki T., Comparison of WB2.5 thin films deposited by pulsed laser deposition and magnetron sputtering, ITFPC'2015, 7th International Conference on Innovations in Thin Film Processing and Characterization, 2015-11-16/11-20, Nancy (FR), pp.94, 2015

Keywords:
pulsed laser deposition, RF magnsteron sputtering, tungsten borides

7.Chrzanowska J., Hoffman J., Denis P., Mościcki T., The effect of substrate heating on the ReB2 layers deposited by PLD method, ITFPC'2015, 7th International Conference on Innovations in Thin Film Processing and Characterization, 2015-11-16/11-20, Nancy (FR), pp.93, 2015
Chrzanowska J., Hoffman J., Denis P., Mościcki T., The effect of substrate heating on the ReB2 layers deposited by PLD method, ITFPC'2015, 7th International Conference on Innovations in Thin Film Processing and Characterization, 2015-11-16/11-20, Nancy (FR), pp.93, 2015

Keywords:
pulsed laser deposition, rhenium borides

8.Mościcki T., Garbiec D., Chrzanowska J., Hoffman J., Pulsed laser deposition of superhard rhenium and tungsten borides, ITFPC'2015, 7th International Conference on Innovations in Thin Film Processing and Characterization, 2015-11-16/11-20, Nancy (FR), pp.99, 2015
Mościcki T., Garbiec D., Chrzanowska J., Hoffman J., Pulsed laser deposition of superhard rhenium and tungsten borides, ITFPC'2015, 7th International Conference on Innovations in Thin Film Processing and Characterization, 2015-11-16/11-20, Nancy (FR), pp.99, 2015

Keywords:
pulsed laser deposition, rhenium borides, tungsten borides

9.Chrzanowska J., Hoffman J., Giżyński M., Mościcki T., Investigation of Wavelength Influence on Rhenium Diboride Films Prepared by PLD Method, INDLAS 2014, 4th International Conference , 2014-05-19/05-23, Bran (RO), pp.24-25, 2014
Chrzanowska J., Hoffman J., Giżyński M., Mościcki T., Investigation of Wavelength Influence on Rhenium Diboride Films Prepared by PLD Method, INDLAS 2014, 4th International Conference , 2014-05-19/05-23, Bran (RO), pp.24-25, 2014

Abstract:
In answer to research interest in production of super hard coatings prepared by pulsed laser deposition (PLD) method, Rhenium Diboride was taken under consideration. PLD is characteristic by necessity to define deposition parameters best for particular substance. ReB2 coatings were prepared with the use of 355 nm and 1064 nm wavelengths of Nd:YAG laser and the influence of laser wavelength on those films preparation was investigated. Deposition efficiency increased with shorter wavelength, however layer’s smoothness was better for longer wavelength. The XRD analysis shows crystalline ReB2 character of achieved samples.

Keywords:
pulsed laser deposition, rhenium diboride

10.Mościcki T., Hoffman J., Antoszewski B., Grabas B., Radziejewska J., Theoretical modelling of laser welding of Ni – Pt spark plug for bio-fuel engine, INDLAS 2014, 4th International Conference , 2014-05-19/05-23, Bran (RO), pp.58-59, 2014
Mościcki T., Hoffman J., Antoszewski B., Grabas B., Radziejewska J., Theoretical modelling of laser welding of Ni – Pt spark plug for bio-fuel engine, INDLAS 2014, 4th International Conference , 2014-05-19/05-23, Bran (RO), pp.58-59, 2014

Abstract:
The interaction of laser beam with dissimilar metals during welding process was studied theoretically. A finite element based three-dimensional transient heat transfer and fluid flow model was applied for prediction temperature distribution and material mixing field as well as weld dimensions. The model was used for study and optimization process parameters of welding of Ni – Pt spark plug for bio-fuel engine. The laser pulse duration and energy, and the angle of incidence of the laser beam to thesurface were analyzed. The shape of the melting pool obtained from the theoretical model was close to experimental results.

11.Mościcki T., Hoffman J., Radziejewska J., Chrzanowska J., Levintant-Zayonts N., Garbiec D., Formation of WB4 thin films using nanosecond Nd-YAG laser, KKNM, 4th National Conference on Nano- and Micromechanics, 2014-07-08/07-10, Wrocław (PL), pp.152-154, 2014
Mościcki T., Hoffman J., Radziejewska J., Chrzanowska J., Levintant-Zayonts N., Garbiec D., Formation of WB4 thin films using nanosecond Nd-YAG laser, KKNM, 4th National Conference on Nano- and Micromechanics, 2014-07-08/07-10, Wrocław (PL), pp.152-154, 2014

Abstract:
Inexpensive Tungsten Tetraboride super hard coatings prepared by pulsed laser deposition (PLD) method are investigated. WB4 coatings were prepared on Si (100), by PLD technique using nanosecond, Nd:YAG laser operating at 355 nm wavelenght. Additionally the surface of SPS sintered WBx target before and after ablation process was examined. Phase change of WB2 to WB4 at the surface of target is observed. The phase analysis, crystallography and orientations have been studied using X-ray diffractometry. The surface layer of target after ablation and deposited films are found to be mostly WB4 phase with hardness HV>28 GPa.

Keywords:
laser mikro/nano engineering, thin films, pulsed laser ablation/deposition, tungsten tetraboride WB4

12.Hoffman J., Mościcki T., Mróz W., Szymański Z., Laser-induced carbon plasma; modelling and experiment, AI30, Acoustical Imaging 30, 2009-03-01/03-04, Monterey, California (US), pp.1-2, 2012