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Kupka T.,University of Opole | Stachow M.,University of Opole | Stachow M.,Institute of Ceramics and Construction Materials | Stobinski L.,Polish Academy of Sciences | Kaminsky J.,Czech Institute of Organic Chemistry And Biochemistry
Magnetic Resonance in Chemistry | Year: 2013

The 3He nuclear magnetic shieldings were calculated for single helium atom, its dimer, simple models of fullerene cages (He@Cn), and single wall carbon nanotubes. The performances of several levels of theory (HF, MP2, DFT-VSXC, CCSD, CCSD(T), and CCSDT) were tested. Two sets of polarization-consistent basis sets were used (pcS-n and aug-pcS-n), and an estimate of 3He nuclear magnetic shieldings in the complete basis set limit using a two-parameter fit was established. Theoretical 3He results reproduced accurately previously reported theoretical values for helium gas, dimer, and helium probe inside several fullerene cages. Excellent agreement with experimental values was achieved. 3He nuclear magnetic shieldings of single helium atom approaching various points of benzene ring were tested, and an impact of 3He confinement within fullerene cages of different size on the 3He chemical shift was determined. Copyright © 2013 John Wiley & Sons, Ltd.


Kupka T.,University of Opole | Stachow M.,Institute of Ceramics and Construction Materials | Kaminsky J.,Czech Institute of Organic Chemistry And Biochemistry | Sauer S.P.A.,Copenhagen University
Magnetic Resonance in Chemistry | Year: 2013

A linear correlation between isotropic nuclear magnetic shielding constants for seven model molecules (CH2O, H2O, HF, F2, HCN, SiH4 and H2S) calculated with 37 methods (34 density functionals, RHF, MP2 and CCSD(T)), with affordable pcS-2 basis set and corresponding complete basis set results, estimated from calculations with the family of polarization-consistent pcS-n basis sets is reported. This dependence was also supported by inspection of profiles of deviation between CBS estimated nuclear shieldings and shieldings obtained with the significantly smaller basis sets pcS-2 and aug-cc-pVTZ-J for the selected set of 37 calculation methods. It was possible to formulate a practical approach of estimating the values of isotropic nuclear magnetic shielding constants at the CCSD(T)/CBS and MP2/CBS levels from affordable CCSD(T)/pcS-2, MP2/pcS-2 and DFT/CBS calculations with pcS-n basis sets. The proposed method leads to a fairly accurate estimation of nuclear magnetic shieldings and considerable saving of computational efforts. Copyright © 2013 John Wiley & Sons, Ltd.


Boczkowska A.,Warsaw University of Technology | Chabera P.,Warsaw University of Technology | Dolata A.J.,Silesian University of Technology | Dyzia M.,Silesian University of Technology | Ozieblo A.,Institute of Ceramics and Construction Materials
Metalurgija | Year: 2013

A pressure-vacuum infiltration (T = 720 °C, p = 15 MPa, t = 15 min) and gas-pressure infiltration (GPI) in an autoclave (T = 700°C, p=4 MPa, t=5 min) were applied for infiltration of porous Al2O3 ceramics by cast aluminum alloy. Eff ect of the method of the infiltration on the microstructure and mechanical properties of ceramic-metal composites, was studied. Ceramic preforms were formed by method of copying the cellular structure of the polymer matrix. The results of the X-ray tomography proved very good infiltration of the pores by the metal for each method.


Boczkowska A.,Warsaw University of Technology | Chabera P.,Warsaw University of Technology | Dolata A.J.,Silesian University of Technology | Dyzia M.,Silesian University of Technology | And 2 more authors.
Solid State Phenomena | Year: 2012

Al2O3/AlSi12CuMgNi composites were fabricated using gas-pressure infiltration (T=700°C, p=4 MPa) of an aluminium alloy into alumina performs. Volume fraction of the ceramic phase was up to 30%, while the pore sizes of the ceramic preforms varied from 300 to 1000 μm. Ceramic preforms were formed by method of copying the cellular structure of the polymer matrix. The results of the X-ray tomography proved very good infiltration of the pores by the aluminium alloy. Residual porosity is approximately 1 vol%. Image analysis has been used to evaluate the specific surface fraction of the interphase boundaries (Sv). The presented results of the studies show the effect of the surface fraction of the interphase boundaries of ceramic-metal on the composite compressive strength, hardness and Young's modulus. The composites microstructure was studied using scanning electron microscopy (SEM). SEM investigations proved that the pores are almost fully filled by the aluminium alloy. The obtained microstructure with percolation of ceramic and metal phases gives the composites high mechanical properties together with the ability to absorb the strain energy. Compression tests for the obtained composites were carried out and Young's modulus was measured by the application of the DIC (Digital Image Correlation) method. Moreover, Brinell hardness tests were performed. Gaspressure infiltration (GPI) allowed to fabricate composites with high compressive strength and stiffness. © (2012) Trans Tech Publications, Switzerland.


Chabera P.,Warsaw University of Technology | Boczkowska A.,Warsaw University of Technology | Ozieblo A.,Institute of Ceramics and Construction Materials | Witek A.,Institute of Ceramics and Construction Materials
ECCM 2012 - Composites at Venice, Proceedings of the 15th European Conference on Composite Materials | Year: 2012

In this paper ceramic-elastomer composites with percolation of ceramics and elastomer phases were reported. They were obtained using segmented urea-urethane elastomer, which was infiltrated as a reactive mixture of the substrates in the liquid form into pores of Al2O3 ceramic preform. The effect of the N-2-(aminoethyl)-3-aminopropyltrimethoxysilane coupling agent on the adhesion of both phases in ceramic- elastomer composites was shown. The degree of wetting was estimated by the value of contact angle as a function of coupling agent amount. The adhesion between phases was estimated from the shear strength.

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