No abstract

Bioinert metals are used for medical implants and in some industrial applications. This study was performed to detect and analyze peculiarities that appear in the temperature distributions during quasi-static tensile testing of bioinert alloys. These alloys include VT1-0 titanium, Zr-1%Nb and Ti-45%Nb in both coarse-grain (CG) and ultrafine-grain (UFG) states. The crystal structure, as well as the crystal domain and grain sizes of these alloys in the UFG state, may be different from the CG versions and identifying the thermal signatures that occur during their deformation and fracture is of interest, as it may lead to an understanding of physical processes that occur during loading. By comparing the surface temperature distributions of specimens undergoing deformation under tensile loading to the distributions at maximum temperatures it was found that the observed differences depend on the alloy type, the alloy structural state and the thermal properties of structural defects in the specimen. Macro-defects were found in some specimens of VT1-0 titanium, Zr-1Nb and Ti-45Nb alloys in both the CG and UFG states. The average tensile strength of specimens containing defects was lower than that of specimens with no defects. Infrared thermography documents change in the thermal patterns of specimens as they are deformed under tensile loading and when the load stops changing or the specimen breaks.

No abstract

No abstract

No abstract

Marquetry method is important in the culture of the Italian community as can be witnessed from the large quantity of artworks that have been realized in this way. The monitoring of the integrity of such pieces poses a great challenge given the need of a reliable and nondestructive technique able to detect surface and subsurface defects. In this work, two ancient marquetry samples containing natural defects were inspected thanks to active thermography by using time-tested, safe and resilient advanced signal processing algorithms (i.e., principal component thermography, correlation contrast, pulsed phase Fourier transform amplitude and phase, cold image subtraction contrast, and polynomial fitting). The latter have been applied to provide a 2D map of the defects.Anyway, in the cultural heritage field, one of the main interest of restorers is the volume of the subsurface defects for structural analyses. The emphasis in this study is placed on the use of dynamic thermal tomography (DTT) as an advanced technique of active thermal non-destructive testing. The main concepts of DTT are illustrated in the manuscript, while a special technique for defect thermal characterization has been used during the second analysis to validate tomographic results. Finally, the position of the main defects retrieved by means of the established techniques applied during the first analysis have been confirmed by DTT.

Summary The catalyst for decomposition of methane to carbon nanofibers and hydrogen was prepared using the solution combustion technique. Dynamics of change of temperature of solution (gel) during the passing of redox reaction of synthesis of catalyst was found experimentally. Testing of catalyst was carried out in a flow through installation. Catalyst with high content of active component 90Ni‐10Al2O3 (wt%) was tested in a reaction of methane decomposition in a temperature range 535°С to 675°С and pressures 1 to 5 atm. The samples of carbon nanofibers were investigated by scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, and X‐ray diffraction. The optimal parameters of catalytic reaction (550°С, 3 atm) providing the high specific yield of hydrogen (287.7 mol/g) were established. The increase of pressure above 1 atm led to prolonged operation of the catalyst. The negative role of temperature rise on the yield of CNFs was found.

No abstract