Instytut Podstawowych Problemów Techniki
Polskiej Akademii Nauk

Partnerzy

Tomasz Wojciechowski

Institute of Physics, Polish Academy of Sciences (PL)

Ostatnie publikacje
1.  Jarząbek D.M., Harvey C., Levintant-Zayonts N., Wojciechowski T., Gniadek M., Krajewski M., Pathak S., Enhancement of mechanical properties of vertically aligned carbon nanotube arrays due to N+ ion irradiation, NANOTECHNOLOGY, ISSN: 0957-4484, DOI: 10.1088/1361-6528/ab8665, Vol.31, No.28, pp.285703-1-9, 2020

Streszczenie:
In this work we apply N+ ion irradiation on vertically aligned carbon nanotube (VACNT) arrays in order to increase the number of connections and joints in the CNT network. The ions energy was 50 keV and fluence 5 × 10^17 ions cm^−2. The film was 160 μm thick. SEM images revealed the ion irradiation altered the carbon bonding and created a sponge-like, brittle structure at the surface of the film, with the ion irradiation damage region extending ~4 μm in depth. TEM images showed the brittle structure consists of amorphous carbon forming between nanotubes. The significant enhancement of mechanical properties of the irradiated sample studied by the cyclic nanoindentation with a flat punch indenter was observed. Irradiation on the VACNT film made the structure stiffer, resulted in a higher percentage recovery, and reduced the energy dissipation under compression. The results are encouraging for further studies which will lead to create a class of materials - ion-irradiated VACNT films - which after further research may find application in storage or harvesting energy at the micro/nanoscale.

Słowa kluczowe:
vertically aligned carbon nanotubes, ion irradiation, nanoindentation

Afiliacje autorów:
Jarząbek D.M. - IPPT PAN
Harvey C. - University of Nevada (US)
Levintant-Zayonts N. - IPPT PAN
Wojciechowski T. - Institute of Physics, Polish Academy of Sciences (PL)
Gniadek M. - Uniwersytet Warszawski (PL)
Krajewski M. - IPPT PAN
Pathak S. - University of Nevada (US)
100p.
2.  Roszkiewicz A., Wojciechowski T., Nasalski W., Kossut J., Raport z formowania struktury soczewki Fresnela i pomiarów jej własności ogniskujących, IPPT Reports on Fundamental Technological Research, ISSN: 2299-3657, Vol.1, pp.1-15, 2020

Streszczenie:
Raport zawiera graficzny zestaw wyników prac prowadzonych w okresie październik 2019 - marzec 2020 w ramach współpracy pomiędzy IPPT PAN i IF PAN. Prace prowadzone w IF PAN dotyczyły nałożenia warstwy złota na płytkę kwarcu i grawerowania w tej warstwie struktury jednowymiarowej soczewki Fresnela. Prace prowadzone w IPPT PAN dotyczyły wyznaczania parametrów geometrycznych wygrawerowanej struktury i charakterystyk jej oddziaływania z padającym polem optycznym. Prace eksperymentalne obu zespołów badawczych pozwoliły na precyzyjne sformowanie jednowymiarowej struktury ogniskującej typu płytki strefowej Fresnela (Fresnel Zone Plate - FZP) o właściwościach zgodnych z wynikami symulacji numerycznych.

Afiliacje autorów:
Roszkiewicz A. - IPPT PAN
Wojciechowski T. - Institute of Physics, Polish Academy of Sciences (PL)
Nasalski W. - IPPT PAN
Kossut J. - Institute of Physics, Polish Academy of Sciences (PL)
3.  Jarząbek D.M., Dziekoński C., Dera W., Chrzanowska J., Wojciechowski T., Influence of Cu coating of SiC particles on mechanical properties of Ni/SiC co-electrodeposited composites, CERAMICS INTERNATIONAL, ISSN: 0272-8842, DOI: 10.1016/j.ceramint.2018.08.271, Vol.44, pp.21750-21758, 2018

Streszczenie:
In this paper, the study of the mechanical properties of composites consisting of electrodeposited Ni and co-electrodeposited SiC particles coated with a thin Cu layer was presented. It was demonstrated that the coating allowed to increase the concentration of ceramic particles in the composite. Although the plating parameters were the same for both types of composites, the concentration of SiC was 15% for the composite containing coated particles (Ni/SiC-Cu) and 10% for the composite containing uncoated particles (Ni/SiC). Furthermore, tensile tests showed that the Ni/SiC-Cu samples exhibited higher Young's modulus than the pure electrodeposited Ni samples or Ni/SiC samples. The measured Young's modulus of the Ni/SiC-Cu composite was 250 ± 10 GPa. However, the ultimate tensile strength of the Ni/SiC-Cu composite was lower than that of pure Ni. To explain the mechanical behaviour of the Ni/SiC-Cu composite, the microstructure of the interface of this composite and its bonding strength were studied. Microstructure studies conducted using a scanning electron microscope (SEM) revealed that the SiC/Cu interface was smooth and of good quality whereas the Cu/Ni interface was rough but also of good quality. The measured bonding, normal, and shear strength values demonstrated that the SiC/Cu interface was weak, and that was the main reason for the low ultimate tensile strength of the composite. The shear strength of the SiC/Cu interface was measured using a novel method: micropillars shearing including atomic force microscopy (AFM). Finally, a simple finite element model of the Ni/SiC-Cu composite, based on cohesive elements, was developed.

Słowa kluczowe:
Interfacial bonding strength, Metal matrix composites, Tensile strength, Silicon carbide, Electrodeposited nickel

Afiliacje autorów:
Jarząbek D.M. - IPPT PAN
Dziekoński C. - IPPT PAN
Dera W. - IPPT PAN
Chrzanowska J. - IPPT PAN
Wojciechowski T. - Institute of Physics, Polish Academy of Sciences (PL)
40p.
4.  Jarząbek D.M., Milczarek M., Wojciechowski T., Dziekoński C., Chmielewski M., The effect of metal coatings on the interfacial bonding strength of ceramics to copper in sintered Cu-SiC composites, CERAMICS INTERNATIONAL, ISSN: 0272-8842, DOI: 10.1016/j.ceramint.2017.01.056, Vol.43, No.6, pp.5283-5291, 2017

Streszczenie:
Cu-SiC composites are very promising materials which have high thermal and electrical conductivity and may find many applications. Unfortunately, the main disadvantage of these materials is the dissolution of silicon in copper at elevated temperature, which significantly reduces their properties. In order to overcome this problem particles can be coated with a protective material before sintering. In this paper– the influence of three different metallic coatings on bonding strength were investigated. SiC particles were coated with tungsten, chromium or titanium. As reference a material with uncoated particles was prepared. The experiments were carried out with the use of microtensile tester. The highest increase in strength was observed in the case of chromium coating. On the other hand, the titanium coating, which was of very poor quality, decrease the bonding strength in comparison with uncoated particles. Furthermore, scanning electron and optical microscopes were used to determine the mechanism of debonding.

Słowa kluczowe:
interfacial bonding strength, metal matrix composites, tensile strength, silicon carbide particles

Afiliacje autorów:
Jarząbek D.M. - IPPT PAN
Milczarek M. - inna afiliacja
Wojciechowski T. - Institute of Physics, Polish Academy of Sciences (PL)
Dziekoński C. - IPPT PAN
Chmielewski M. - Institute of Electronic Materials Technology (PL)
40p.
5.  Jarząbek D.M., Chmielewski M., Wojciechowski T., The measurement of the adhesion force between ceramic particles and metal matrix in ceramic reinforced-metal matrix composites, COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING, ISSN: 1359-835X, DOI: 10.1016/j.compositesa.2015.05.025, Vol.76, pp.124-130, 2015

Streszczenie:
This paper presents the method for measurement of the adhesion force and fracture strength of the interface between ceramic particles and metal matrix in ceramic reinforced-metal matrix composites. Three samples with the following Cu to Al2O3 ratio (in vol.%) were prepared: 98.0Cu/2.0Al2O3, 95.0Cu/5.0Al2O3 and 90Cu/10Al2O3. Furthermore, microwires which contain a few ceramic particles were produced by means of electro etching. The microwires with clearly exposed interface were tested with use of the microtensile tester. The microwires usually break exactly at the interface between the metal matrix and ceramic particle. The force and the interface area were carefully measured and then the fracture strength of the interface was determined. The strength of the interface between ceramic particle and metal matrix was equal to 59 ± 8 MPa and 59 ± 11 MPa in the case of 2% and 5% Al2O3 to Cu ratio, respectively. On the other hand, it was significantly lower (38 ± 5 MPa) for the wires made of composite with 10% Al2O3.

Słowa kluczowe:
Nanocomposites, Metal matrix composites, Adhesion, Interface

Afiliacje autorów:
Jarząbek D.M. - IPPT PAN
Chmielewski M. - Institute of Electronic Materials Technology (PL)
Wojciechowski T. - Institute of Physics, Polish Academy of Sciences (PL)
50p.
6.  Wojnar P., Zieliński M., Janik E., Zaleszczyk W., Wojciechowski T., Wojnar R., Szymura M., Kłopotowski Ł., Baczewski L.T., Pietruchik A., Wiater M., Kret S., Karczewski G., Wojtowicz T., Kossut J., Strain-induced energy gap variation in ZnTe/ZnMgTe core/shell nanowires, APPLIED PHYSICS LETTERS, ISSN: 0003-6951, DOI: 10.1063/1.4873355, Vol.104, pp.163111-1-5, 2014

Streszczenie:
Strain-induced changes of ZnTe energy gap in ZnTe/ZnMgTe core/shell nanowires arising from lattice mismatch between the core and the shell semiconductor are studied by means of optical methods. It is shown that the increase of the Mg content in the shell, as well as the increase of the shell thickness result in an effective redshift of the near band edge photoluminescence from ZnTe nanowire cores, which reflects directly the decrease of energy gap under tensile strain conditions. The conclusions are supported by theoretical calculations in terms of the valence force field model. The observed change of ZnTe energy gap can be as large as 120 meV with respect to the unstrained conditions and can be tuned in a continuous manner by adjusting shell parameters, which open a path towards an effective band gap engineering in these structures.

Słowa kluczowe:
Nanowires, II-VI semiconductors, Magnesium, Band gap, Quantum effects

Afiliacje autorów:
Wojnar P. - Institute of Physics, Polish Academy of Sciences (PL)
Zieliński M. - inna afiliacja
Janik E. - inna afiliacja
Zaleszczyk W. - inna afiliacja
Wojciechowski T. - Institute of Physics, Polish Academy of Sciences (PL)
Wojnar R. - IPPT PAN
Szymura M. - inna afiliacja
Kłopotowski Ł. - inna afiliacja
Baczewski L.T. - Institute of Physics, Polish Academy of Sciences (PL)
Pietruchik A. - Institute of Physics, Polish Academy of Sciences (PL)
Wiater M. - Institute of Physics, Polish Academy of Sciences (PL)
Kret S. - Institute of Physics, Polish Academy of Sciences (PL)
Karczewski G. - inna afiliacja
Wojtowicz T. - Institute of Physics, Polish Academy of Sciences (PL)
Kossut J. - Institute of Physics, Polish Academy of Sciences (PL)
40p.
7.  Majkowski P., Wojciechowski T., Wojtyński M., Kotulski Z., Rawski M., Analiza możliwości sprzętowej kryptoanalizy szyfrów opartych na krzywych eliptycznych, POMIARY AUTOMATYKA KONTROLA, ISSN: 0032-4140, Vol.54, No.8, pp.536-539, 2008

Abstrakty konferencyjne
1.  Jarząbek D.M., Harvey C., Levintant-Zayonts N., Daraio C., Dziekoński C., Wojciechowski T., Gniadek M., Pathak S., Mechanical properties of N+ion irradiated vertically aligned carbon nanotube arrays studied by nanoindentation, EUROMAT 2019, European Congress and Exhibition on Advanced Materials and Processes 2019, 2019-09-01/09-05, Stockholm (SE), No.PM6-5, pp.464, 2019
2.  Jarząbek D.M., Chmielewski M., Wojciechowski T., The measurement of the adhesion force between ceramic particles and metal matrix in ceramic reinforced-metal matrix composites, Nanomechanical Testing in Materials Research and Development V, 2015-10-04/10-09, Albufeira (PT), pp.1, 2015
3.  Jarząbek D.M., Chmielewski M., Wojciechowski T., The measurement of the adhesion force between ceramic particles and metal matrix in ceramic reinforced-metal matrix composites, EUROMAT 2015, European Congress and Exhibition on Advanced Materials and Processes, 2015-09-20/09-24, Warszawa (PL), pp.1, 2015

Streszczenie:
This paper presents the method for measurement of the adhesion force and fracture strength of the interface between ceramic particles and metal matrix in ceramic reinforced-metal matrix composites. Three samples with the following Cu to Al 2 O 3 ratio (in vol.%) were prepared: 98.0Cu/2.0Al 2 O 3, 95.0Cu/5.0Al 2 O 3 and 90Cu/10Al 2 O 3. Furthermore, microwires which contain a few ceramic particles were produced by means of electro etching. The microwires with clearly exposed interface were tested with use of the microt ensile tester (Fig. 1). The microtensile tester consists of two stages, to which two endings of the microwire are fixed. The first stage is able to measure force with the precision equal to 0.1 mN. The microwires usually break exactly at the interface between the metal matrix and ceramic particle. The force and the interface area were carefully measured and then the fracture strength of the interface was determined. The strength of the interface between ceramic particle and metal matrix was equal to 59 ±8 MPa and 59±11 MPa in the case of 2% and 5% Al 2 O 3 to Cu ratio, respectively. On the other hand, it was significantly lower (38±5 MPa) for the wires made of composite with 10% Al2O3

Afiliacje autorów:
Jarząbek D.M. - IPPT PAN
Chmielewski M. - Institute of Electronic Materials Technology (PL)
Wojciechowski T. - Institute of Physics, Polish Academy of Sciences (PL)

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