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Ultrasonic testing of grain distortion direction in cold formed aluminium profile

Keran Z., Mihaljević M., Runje B., Markučič D.

Archives of Civil and Mechanical Engineering

2017

Vol. 17, no. 2

375--381

Cold deformation process of metals causes distortion of crystalline structure. When a material is formed, the grains are usually distorted and elongated in one or more directions which make the material anisotropic. Anisotropy can be defined as a difference in a material's physical or mechanical properties in different directions of taking of testing samples. In exploitation, it is very important to recognize the direction of grain elongation so that the best orientation of working part can be chosen. For that purpose ultrasonic testing is used. The ultrasonic velocity of the material is determined by using a digital oscilloscope under condition that thickness of the material is known. Testing shows the difference in wave velocity for different orientations of grain structure. In order to determine whether there is a significant difference in the ultrasonic velocity, the measurement results were statistically analyzed and graphically presented. The results are verified by performing the same measurement procedure on annealed homogenous testing samples. The result of this work leads to a non-destructive, simplified way of anisotropy recognition, without more expensive, destructing, testing by cutting out a large number of testing samples.

Investigation of the Acoustic Properties of Viscosity Standards

Kazys R., Voleisis A., Sliteris R.

Archives of Acoustics

2016

Vol. 41, No. 1

55--58

Longitudinal and shear ultrasonic wave velocities were measured versus temperature in the viscosity standards of Paragon S8000S, N30000S and Cannon N2700000. The measurements were performed by the through-transmission method at the frequency of 2 MHz. Ultrasonic pulses were sent via polymethyl methacrylate (PMMA) waveguides between the tips of which a small amount of the particular standard liquid was placed. The velocities of longitudinal and shear waves were determined to depend on the viscosity of the liquid and increase with the viscosity.

Electronic and magnetic dynamic properties of imidazolate complexes

Ragot F., Belin S., Ivanov V. G., Perry D. L., Ortega M., Ignatova T. V., Kolobov I. G., Masalitin E. A., Kamarchuk G. V., Yeremenko A. V., Molinié P., Wéry J., Faulques E.

Materials Science

2002

Vol. 20, No. 3

11-27

Transition-metal complexes of imidazole ImH (C3H4N2) are relevant for the study of metalloenzymes and protein folding. Moreover, these materials could lead to potential applications such as electrochromic displays, photovoltaic cells and biomaterials. A series of metal-imidazole complexes of general formula + - x Mx Im (where x = 1, 2, M = Ag, Zn, Co, Cu and Im- = C3H3N2 is the deprotonated form of ImH) was synthesized and comprehensively studied as model materials for metalloproteins and molecular magnets. Their atomic dynamic properties were investigated with X-ray diffraction, XANES, EXAFS, vibrational spectroscopy and magnetic techniques. Metal-ligand bond lengths and force constans were estimated. The relationship between these structural data and rich spin dynamics revealed for M = Cu, Co bis-imidazolate compounds is discussed.