Instytut Podstawowych Problemów Techniki
Polskiej Akademii Nauk

Pracownicy

Stefania Woźniacka

Zakład Mechaniki Materiałów (ZMM)
Pracownia Warstwy Wierzchniej (PWW)
stanowisko: starszy technik dokumentalista
telefon: (+48) 22 826 12 81 wewn.: 141
pokój: 231
e-mail:
ORCID: 0000-0003-1055-4392

Ostatnie publikacje
1.  Kucharski S., Mackiewicz S., Katz T., Starzyński G., Ranachowski Z., Woźniacka S., Evaluation of fatigue damage of a railhead using an indentation test, acoustic methods and microstructural observations, INTERNATIONAL JOURNAL OF FATIGUE, ISSN: 0142-1123, DOI: 10.1016/j.ijfatigue.2022.107346, pp.107346-1-107346-13, 2022

Streszczenie:
The paper presents an investigation of the railhead steel R260. Brinell hardness was measured, spherical microindentation tests were performed and the microstructure was analysed using optical microscopy and SEM images. Fatigue damage in various near-surface regions of the railhead was estimated on the basis of local deterioration of elastic modulus and the development of plastic work in cyclic microindentation tests. There is a clear difference in hardness and fatigue damage between the used and the virgin regions of the railhead. The Brinell hardness and ultrasonic measurements show a change in material properties due to rail manufacturing process.

Słowa kluczowe:
Fatigue damage, Microindentation, Brinell hardness, Ultrasonic measurements, Railhead

Afiliacje autorów:
Kucharski S. - IPPT PAN
Mackiewicz S. - IPPT PAN
Katz T. - IPPT PAN
Starzyński G. - IPPT PAN
Ranachowski Z. - IPPT PAN
Woźniacka S. - IPPT PAN
140p.
2.  Maj J., Węglewski W., Bochenek K., Rogal Ł., Woźniacka S., Basista M., A comparative study of mechanical properties, thermal conductivity, residual stresses, and wear resistance of aluminum-alumina composites obtained by squeeze casting and powder metallurgy, METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE, ISSN: 1073-5623, DOI: 10.1007/s11661-021-06401-7, pp.1-10, 2021

Streszczenie:
Squeeze casting and powder metallurgy techniques were employed to fabricate AlSi12/Al2O3 composites, which are lightweight structural materials with potential applications in the automotive industry. The impact of the processing route on the material properties was studied. Comparative analyses were conducted for the Vickers hardness, flexural strength, fracture toughness, thermal conductivity, thermal residual stresses, and frictional wear. Our results show that the squeeze cast composite exhibits superior properties to those obtained using powder metallurgy.

Afiliacje autorów:
Maj J. - IPPT PAN
Węglewski W. - IPPT PAN
Bochenek K. - IPPT PAN
Rogal Ł. - Institute of Metallurgy and Materials Science, Polish Academy of Sciences (PL)
Woźniacka S. - IPPT PAN
Basista M. - IPPT PAN
200p.
3.  Kucharski S., Woźniacka S., Size effect in single crystal copper examined with spherical indenters, METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE, ISSN: 1073-5623, DOI: 10.1007/s11661-019-05160-w, Vol.50A, pp.2139-2154, 2019

Streszczenie:
The increasing hardness with decreasing penetration depth, referred to as indentation size effect (ISE) was previously investigated experimentally and theoretically by many researchers, however the mechanisms responsible for ISE are still being discussed. Generally, ISE is related to the density of geometrically necessary dislocation stored within a small volume beneath the indenter tip. In this study ISE is investigated experimentally in a single crystal copper using spherical indenter tips of different radii. Some new aspects of ISE are shown: a qualitative change of shape of residual impression (pile-up/sink-in pattern) when tip radius or load is modified, an increase of maximum pop-in load with decrease of tip radius as well as the well-known increase of hardness when tip radius decreases are analyzed. As we observe a difference of the residual imprint morphology which depends on tip radius and load, we apply two methods of hardness estimation: true hardness and nominal hardness. The former is determined on the basis of direct measurement of the contact area while accounting for a specific pile-up pattern, while the latter is determined by measuring the contact area using residual penetration depth. We show that hardness–tip radius relationship has a linear form for the nominal hardness and bilinear form for the true hardness.

Afiliacje autorów:
Kucharski S. - IPPT PAN
Woźniacka S. - IPPT PAN
200p.
4.  Chrzanowska-Giżyńska J., Denis P., Woźniacka S., Kurpaska Ł., Mechanical properties and thermal stability of tungsten boride films deposited by radio frequency magnetron sputtering, CERAMICS INTERNATIONAL, ISSN: 0272-8842, DOI: 10.1016/j.ceramint.2018.07.208, Vol.44, No.16, pp.19603-19611, 2018

Streszczenie:
Tungsten and boron compounds belong to the group of superhard materials since their hardness could exceed 40 GPa. In this study, the properties of the tungsten boride WBx coatings deposited by radio frequency magnetron sputtering were investigated. The sputtering was performed from specially prepared targets that were composed of boron and tungsten mixed in a molar ratio of 2.5 and sintered in Spark Plasma Sintering (SPS) process. WB films were deposited on silicon (100) and stainless steel 304 substrates at temperatures of 23 ÷ 770 °C. Microstructure, chemical and phase composition were investigated by using Scanning Electron Microscope (SEM), X-Ray Photoelectron Spectroscopy (XPS) and X-Ray Diffraction (XRD), respectively. The mechanical properties like Vickers hardness and Young's modulus were obtained by using nanoindentation test at a load of 5 ÷ 100 mN. The friction coefficient and wear resistance of αWB coatings were investigated in scratch test and reciprocal sliding wear instrumentation. Moreover, in order to investigate thermal properties, the αWB films were annealed at 1000 °C in argon/air for 1 h and at 250 °C for 2 h in air atmosphere. Results of our research confirm that αWB coatings can be considered as an alternative to superhard materials in the production of wear resistant, long-lasting tools.

Słowa kluczowe:
Hard coatings, Hard materials, Magnetron sputtering, Mechanical properties, Thermal properties, Tungsten boride

Afiliacje autorów:
Chrzanowska-Giżyńska J. - IPPT PAN
Denis P. - IPPT PAN
Woźniacka S. - IPPT PAN
Kurpaska Ł. - National Centre for Nuclear Research (PL)
40p.
5.  Kucharski S., Jarząbek D.M., Piątkowska A., Woźniacka S., Decrease of Nano-hardness at Ultra-low Indentation Depths in Copper Single Crystal, EXPERIMENTAL MECHANICS, ISSN: 0014-4851, DOI: 10.1007/s11340-015-0105-2, Vol.56, No.3, pp.381-393, 2016

Streszczenie:
In the present study, we report a detailed investigation of the unusual size effect in single crystals. For the experiments we specified the hardness in single crystalline copper specimens with different orientations ((001), (011) and (111)) using Oliver-Pharr method. Our results indicates that with decreasing load, after the value of the hardness reached its maximum, it starts to decrease for very small indentation depths (<150 nm). For the sake of accuracy of hardness determination we have developed two AFM-based methods to evaluate contact area between tip and indented material. The proposed exact measurement of the contact area, which includes the effect of pile-up and sink-in patterns, can partially explain the strange behaviour, however, the decrease of hardness at low loads is still observed. At higher loads range the specified hardness is practically constant.

Słowa kluczowe:
Copper, Single crystal, Nanoindentation, AFM, Size effect

Afiliacje autorów:
Kucharski S. - IPPT PAN
Jarząbek D.M. - IPPT PAN
Piątkowska A. - Institute of Electronic Materials Technology (PL)
Woźniacka S. - IPPT PAN
35p.

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