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Influence of Surface Laser Treatment on Mechanical Properties and Residual Stresses of Titanium and its Alloys

Jażdżewska Magdalena, Majkowska-Marzec Beata, Ostrowski Roman, Olive Jean-Marc

Advances in Science and Technology. Research Journal

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2023

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Vol. 17, no 6

27--38

EN

Surface modification of the titanium and its alloys used in implantology with a long-pulse laser can change the surface topography, but it also leads to changes in the stress sign and magnitude in the resulting subsurface layer. The presented research was aimed at evaluating the state of stress after laser remelting with the Nd:YAG laser of pre-etched titanium alloys Ti6Al4V and Ti13Nb13Zr and pure titanium. The obtained surface layers were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), optical profilography, and nanoindentation studies. Based on the results obtained after the nanoindentation tests, the character of the stresses generated in the melted layers was calculated and determined. Laser processing resulted in surface layer thicknesses between 191-320 µm and surface roughness Ra between 2.89-5.40 µm. Laser processing caused increasing hardness, and its highest value was observed for the titanium alloy Ti13Nb13Zr - 5.18 GPa. The tensile stresses appeared following laser treatment and increased with elevating laser power up to the highest value for titanium.

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Effect of pulse laser treatment at different process variables on mechanical behavior of carbon nanotubes electrophoretically deposited on titanium alloy

Majkowska-Marzec Beata, Staszewski Kacper, Sypniewska Joanna

Acta of Bioengineering and Biomechanics

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2023

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Vol. 25, no. 2

157--168

EN

Titanium and its alloys are widely used as biomaterials for long-term implants, but they are usually surface-modified due to their weak bioactivity and wear resistance. Laser processing was used to modify the surface layer, and elemental carbon was a component of the deposited coatings. This research aims to use a combination of both methods based on preliminary electrophoretic deposition of multi-wall carbon nanotubes (MWNCTs) followed by pulse laser treatment. Carbon nanotubes were chosen due to their mechanical and chemical stability as well as their tubular shape, resulting in enhanced mechanical properties of laser-modified layers. Methods: The pulse laser power and laser scanning speed were defined as variable process parameters. The microstructure, roughness Ra, nanohardness H, Young’s modulus E, and indent depth values were measured, and the H/E, H 3 /E2 , and relative changes of all these values in comparison to MWCNTs-coated and non-coated surfaces, were calculated. Results: The obtained results show that the best mechanical properties of MWCNTs-coated and laser-treated specimens are obtained at a laser power of 900 W and laser feed of 6 mm/s. The observed relations can be explained considering processes occurring on the surface such as deposition of carbon nanotubes, melting and re-crystallization of the surface layer, formation and possible partial decomposition of titanium carbides, and associated changes in local chemical composition, phase composition, and a level of residual stresses beneath the surface. Conclusions: The developed process can substitute the time and money-consuming carbonization of titanium and its alloys.

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Microstructure and mechanical properties of laser surface-treated Ti13Nb13Zr alloy with MWCNTs coatings

Majkowska-Marzec Beata, Sypniewska Joanna

Advances in Materials Science

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2021

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Vol. 21, nr 4(70)

5--18

EN

Laser surface modification of titanium alloys is one of the main methods of improving the properties of titanium alloys used in implantology. This study investigates the microstructural morphology of a laser-modified surface layer on a Ti13Nb13Zr alloy with and without a carbon nanotube coating deposited by electrophoretic deposition. Laser modification was performed for samples with and without carbon nanotube coating for two different laser powers of 800 W and 900 W and for different scan rates: 3 mm/s or 6 mm/s at 25 Hz, and the pulse duration was 2.25 ms or 3.25 ms. A scanning electron microscope SEM was used to evaluate the surface structure of the modified samples. To observe the heat-affected zones of the individual samples, metallographic samples were taken and observed under an optical microscope. Surface wettability tests were performed using a goniometer. A surface roughness test using a profilograph and a nanoindentation test by NanoTest™ Vantage was also performed. Observations of the microstructure allowed to state that for higher laser powers the surfaces of the samples are more homogeneous without defects, while for lower laser powers the path of the laser beam is clearer and more regular. Examination of the microstructure of the cross-sections indicated that the samples on which the carbon nanotube coating was deposited are characterized by a wider heat affected zone, and for the samples modified at 800 W and a feed rate of 3 mm/s the widest heat affected zone is observed. The wettability tests revealed that all the samples exhibit hydrophilic surfaces and the samples with deposited carbon nanotube coating increase it further. Surface roughness testing showed a significant increase in Ra for the laser-modified samples, and the presence of carbon nanotubes further increased this value. Nanoindentation studies showed that the laser modification and the presence of carbon coating improved the mechanical properties of the samples due to their strength.

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Wpływ metody trawienia i spiekania na właściwości mechaniczne powłok z nanorurek węglowych osadzonych elektroforetycznie na podłożu Ti13Nb13Zr

Rogala-Wielgus Dorota, Majkowska-Marzec Beata

Inżynier i Fizyk Medyczny

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2019

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Vol. 8, nr 5

417--420

PL

Do eksperymentu użyto stopu tytanu Ti13Zr13Nb, który ze względu na swój skład chemiczny i właściwości mechaniczne stanowi doskonały materiał do zastosowań w inżynierii medycznej. Celem pracy była ocena wpływu przygotowania podłoża (rodzaj zastosowanego odczynnika trawiącego) oraz obróbki końcowej (proces spiekania) powłok z wielościennych nanorurek węglowych na ich właściwości mechaniczne (nanotwardość, moduł Younga). Do wytworzenia powłoki węglowej wykorzystano metodę osadzania elektroforetycznego (EDP). Porównano działanie dwóch odczynników trawiących: 5% roztworu kwasu fluorowodorowego i 25% roztworu kwasu azotowego (V). Właściwości mechaniczne zmierzono za pomocą nanoindentera, a mikrostrukturę powierzchni badano z użyciem skaningowego mikroskopu elektronowego (SEM). Zarówno rodzaj odczynnika trawiącego, jak i zastosowanie obróbki spiekaniem wpływa na mikrostrukturę powierzchni oraz właściwości otrzymanych powłok z nanorurek węglowych.

EN

The titanium alloy Ti13Zr13Nb was used as a substrate, because of its chemical composition and good mechanical properties in application of tissue engineering. The aim of the work was the assessment of the influence of a substrate preparation (a kind of etching agent) and a final treatment (a sintering process) of multi-walled carbon nanotube’s coating for mechanical properties (nanohardness, Young modulus). Electrophoretic deposition (EDP) method was used to prepare carbon coating. The effect of two etching agents: 5% hydrofluoric acid solution, 25% nitric acid solution was compared. Mechanical properties were checked with nanoindenter and surface microstructure with scanning electron microscope (SEM). Both, the kind of etching agent and sintering process carried out affects surface microstructure, and properties of achieved carbon nanotubes coatings.

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The influence of laser alloying of Ti13Nb13Zr on surface topography and properties

Tęczar P., Majkowska-Marzec Beata, Bartmański Michał

Advances in Materials Science

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2019

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Vol. 19, nr 1(59)

44--56

EN

The laser alloying is a continually developing surface treatment because of its significant and specific structuration of a surface. In particular, it is applied for Ti alloys, being now the most essential biomaterials` group for load-bearing implants. The present research was performed on the Ti13Nb13Zr alloy subject to laser modification in order to determine the treatment effects on surface topography and its some mechanical properties like nanohardness, Young's modulus, roughness. A pulse laser Nd:YAG was applied at three different laser pulse regimes: either 700 W, 1000 W or 1000 W treatment followed by 700 W modification at a pulse duration of 1 ms. The surface topography and morphology were examined using light microscopy and scanning electron microscopy with spectroscope of X-ray energy dispersion. The mechanical properties were determined by nanoindentation tests and surface roughness with a use of profilograph. The wettability was tested with a goniometer. The obtained results demonstrate complex behavior of the material surface: decrease in penetration distance and increase in hardness after first laser treatment, maintenance of this trend when machining using a higher laser pulse power, followed by an increase in penetration and decrease in hardness after additional laser treatment at lower power input, due to which a surface with fewer defects is obtained. The change in Young`s modulus follows the change in other mechanical properties, but not a change in roughness. Therefore, the observed hardening with the increase of the laser pulse power and then a small softening with the use of additional treatment with lower power can be attributed to some processes of remelting, diffusion and crystallization, sensitive to the previous surface state and heat energy flux. Despite that, the laser treatment always caused a significant hardening of the surface layer.