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Superconductivity at 9.5 K in the Ti2GeC compound

Bortolozo A. D., Sant'Anna O. H., Dos Santos C. A. M., Machado A. J. S.

Materials Science Poland

2012

Vol. 30, No. 2

92--97

We report on the investigation of the Ti2GeC properties by X-ray diffraction, magnetic and electrical resistivity measurements. Polycrystalline samples of Ti2GeC with nominal compositions were prepared by solid state reaction. X-ray powder patterns suggest that all peaks can be indexed with the hexagonal phase of Cr2AlC prototype. The temperature dependence of both electrical resistivity and magnetization indicate a bulk type-II superconductivity at 9.5 K. Magnetoresistive data suggest an upper critical field of Bc2 -- 8.1 T and coherence length - 61 A° . Furthermore, the results highlight the highest critical temperature reported up to now for an H-phase.

Hard and superhard nanolaminate and nanocomposite coatings for machine elements based on Ti6Al4V alloy

Wendler B., Moskalewicz T., Progalskiy I., Pawlak W., Makówka M., Włodarczyk K., Nolbrzak P., Czyrska-Filemonowicz A., Rylski A.

Journal of Achievements in Materials and Manufacturing Engineering

2010

Vol. 43, nr 1

455--462

Purpose: Verification of a series of hybrid treatments of Ti6Al4V alloy consisting of primary diffusion hardening of the substrate with subsequent deposition of wear resistant coatings. Design/methodology/approach: Different nanolaminate and nanocomposite coatings were deposited with use of four different methods including a newly developed high density gas pulsed plasma MS technique. After deposition the coatings were investigated using OM, SEM, HRTEM, XRD, XPS, nanoindentation, Daimler-Benz, ball-on-plate and scratch tests. Findings: Besides an important increase of Ti6Al4V alloy hardness much greater further increase of hardness was obtained due to coatings deposition up to 53 GPa in case of a nanolaminate coating and to 47 GPa in case of a nanocomposite nc-TiN/a-SiN coating. At the same time the volume wear coefficient decreases several orders of magnitude for all the coatings. Simultaneously the friction coefficient decreased to a great extent except for the nc-TiN/a-SiN coating. Research limitations/implications: High density gas pulsed plasma magnetron sputtering is an effective method for superhard coatings deposition, however the roughness of the deposited nc-TiN/a-SiN coating was greater than after conventional magnetron sputtering. This finding needs further experimental and theoretical investigation. Practical implications: Greater surface roughness and high resistance to wear of the coatings synthesized using the newly developed gas pulsed plasma magnetron sputtering deposition limits their application to wear protection of cutting tools rather than for friction reduction in tribological couples. Originality/value: Applicability of the broad spectrum of nanolaminate and nanocomposite coatings as well as different CVD and PVD techniques for an improvement of tribological properties of Ti6Al4V alloy was analyzed in the paper including a newly developed original high density gas pulsed plasma magnetron sputtering technique.

Synthesis and properties of hot-pressed Ti-Al-C-N materials

Chlubny L., Lis J., Bućko M. M.

Inżynieria Materiałowa

2010

Vol. 31, nr 3

495-498

Ternary and quaternary materials in Ti-Al-C-N system are specific due to the heterodesmic character of chemical bounds. Such materials can combine properties of ceramics and metal. In the paper SHS synthesis of powders with different stoichiometry, Ti2AlN, Ti3AlC2 and Ti3Al(C, N)2 with usage of intermetallic compounds as precursors is presented. The powders were hot-presses and mechanical and structural properties of dense bodies were examined.

Potrójne oraz poczwórne materiały należące do układu Ti-Al-C-N zwracają na siebie uwagę ze względu na szczególne właściwości, plasujące je pomiędzy materiałami metalicznymi i ceramicznymi. W niniejszej pracy przedstawiono proces syntezy SHS, w wyniku której otrzymywano proszki Ti2AlN, Ti3AlC2 i Ti3Al(C, N)2. Jako substraty stosowane były samodzielnie otrzymywane proszki międzymetaliczne z układu Ti-Al. Otrzymane proszki materiałów potrójnych i poczwórnych prasowano na gorąco. Następnie badano właściwości mechaniczne i strukturalne otrzymanych gęstych spieków.