Papers by Petrica Vizureanu
The paper presents a comparative study about the modifications of microstructure and mechanical p... more The paper presents a comparative study about the modifications of microstructure and mechanical properties, for 2 alloys for Co-Cr-Mo system alloys. The structural modification are evidenced by complex microscopic analysis made on a metallographic microscope and an electronic microscope coupled with EDX detector, but also by X-ray diffraction analysis, determining the inter-metallic compounds and phases specific to cast state of analyzed alloys. In terms of mechanical properties, the standard samples from analyzed alloys was subject to tensile test and hardness measurements. The obtained values both for CoCrMoSi1Mn1 alloy, and for allied alloys with 5%Si (CoCrMoSi5Mn1), are subject to standard limits of metallic alloys, with medical applications.
Revista de Chimie -Bucharest- Original Edition-
The paper presents a comparative study about the modifications of microstructure and mechanical p... more The paper presents a comparative study about the modifications of microstructure and mechanical properties, for 2 alloys for Co-Cr-Mo system alloys. The structural modification are evidenced by complex microscopic analysis made on a metallographic microscope and an electronic microscope coupled with EDX detector, but also by X-ray diffraction analysis, determining the inter-metallic compounds and phases specific to cast state of analyzed alloys. In terms of mechanical properties, the standard samples from analyzed alloys was subject to tensile test and hardness measurements. The obtained values both for CoCrMoSi1Mn1 alloy, and for allied alloys with 5%Si (CoCrMoSi5Mn1), are subject to standard limits of metallic alloys, with medical applications.
The paper presents the study of corrosion phenomena for CoCrMo and CoCrMoSi5 alloys, in biologica... more The paper presents the study of corrosion phenomena for CoCrMo and CoCrMoSi5 alloys, in biological fluids, like citric acid (unpasteurized fresh orange juice). The study was made by electrochemical methods, using potentio-dynamic method and electrochemical impedance spectroscopy. It was found that CoCrMoSi5 alloy present high properties and may be used to medical applications.
Materials Science Forum, 2014
ABSTRACT Aluminum alloys have special advantages on the structural changes induced by thermal tre... more ABSTRACT Aluminum alloys have special advantages on the structural changes induced by thermal treatments. Thus, for proper machining a solution quenching is applied, when the hardness and the tensile strength of the alloy decreases. In order to restore the properties natural or artificial ageing is necessary.
2013 E-Health and Bioengineering Conference (EHB), 2013
ABSTRACT
Journal of Biomedical Materials Research, 2003
A novel approach to electrochemical processing of hydroxyapatite (HA) coating was explored. Vinyl... more A novel approach to electrochemical processing of hydroxyapatite (HA) coating was explored. Vinyl acetate was added in the electrolytes of calcium and phosphorous in order to improve the adhesion between HA coating and titanium substrate. X-ray powder diffractometer (XRD) spectra indicated that the vinyl acetate did not interfere with the deposition of HA on the surface of titanium cathodes. X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) results revealed that both vinyl acetate and HA were deposited on the titanium cathodes. The vinyl acetate changed the HA crystalline morphology in the deposition layer. The shape and growth direction of the HA crystals in the coating with vinyl acetate differed from those of HA deposition along. The addition of vinyl acetate increased the coating strength considerably, even though further improvement is needed for clinical applications. Moreover, a preliminary study of the bioactivity showed that osteoblastic cells exhibited higher cell proliferation potential on the HA/vinyl acetate coating than on that of pure HA.
The paper presents a study on alloy CuAlMnFe, analyzed in terms of phases and structural aspects ... more The paper presents a study on alloy CuAlMnFe, analyzed in terms of phases and structural aspects and physical and mechanical properties, after some heat treatments like annealing, quenching and tempering.
This paper presents experimental tests made on samples of type RUL2 steel sample subjected to hea... more This paper presents experimental tests made on samples of type RUL2 steel sample subjected to heat treatments annealing, hardening martensitic and low recovery. Improving the physical and mechanical characteristics of bearing steels used in construction machinery is a prerequisite to ensure the best reliability bearing.
Key Engineering Materials, 2013
The paper presents the obtaining of shape memory alloys, base copper and a diffractometer and mic... more The paper presents the obtaining of shape memory alloys, base copper and a diffractometer and microscopic study on some samples. The study was made on CuZnAl samples, obtained by classic casting and educated. The shape memory alloys properties recommend their use for applications in domains as follows electric contacts, robotics, and aeronautics. When choosing the type of alloy used for the manufacture of the component parts of different industrial applications, it must be taken into account fatigue resistance, resistance to shocks and resistance to corrosion. Shape memory alloys are a unique group of alloys with the ability to remember a form even after quite severe plastic deformations. At low temperatures, shape memory alloys can be deformed apparently like other metallic alloys, but this deformation can recover with a relatively modest increase in temperature. 2. The second stage involves storing tension, by the action of external forces, the martensitic state, strong macles. Macroscopic deformation occurs by migration limits macles and increases those variables that are most favorably oriented to the applied voltage.
Research in Nondestructive Evaluation, 2008
The remote field eddy current (RFEC) technique is used to investigate the possibility of detectin... more The remote field eddy current (RFEC) technique is used to investigate the possibility of detecting the discontinuities practiced on pressure tubes samples from nuclear reactors, pressurized heavy water reactors (PHWR) type. In this article, we propose to develop the RFEC using the technique of rotating magnetic field (RMF). A method for calculating the field generated by the eddy current transducer
Physica Scripta, 2008
ABSTRACT Considering that the chaotic effect of associated wave packet on the particle itself res... more ABSTRACT Considering that the chaotic effect of associated wave packet on the particle itself results in movements on the fractal (continuous and non-differentiable) curves of fractal dimension DF, wave–particle duality through an extension of the scale relativity theory is given. It results through an equation of motion for the complex speed field, that in a fractal fluid, the convection, dissipation and dispersion are reciprocally compensating at any scale (differentiable or non-differentiable). From here, for an irrotational movement, a generalized Schrödinger equation is obtained. The absence of dispersion implies a generalized Navier–Stokes type equation, whereas, for the irrotational movement and the fractal dimension, DF = 2, the usual Schrödinger equation results. The absence of dissipation implies a generalized Korteweg–de Vries type equation. In such conjecture, at the differentiable scale, the duality is achieved through the flowing regimes of the fractal fluid, i.e. the wave character by means of the non-quasi-autonomous flowing regime and the particle character by means of the quasi-autonomous flowing regime. These flowing regimes are separated by '0.7 structure'. At the non-differentiable scale, a fractal potential acts as an energy accumulator and controls through the coherence the duality. The correspondence between the differentiable and non-differentiable scales implies a Cantor space-time. Moreover, the wave–particle duality implies at any scale a fractal.
Japanese Journal of Applied Physics, 2009
The formation and dynamics of aluminum laser produced plasma are experimentally and theoretically... more The formation and dynamics of aluminum laser produced plasma are experimentally and theoretically investigated. The visible emitting regions of plasma form two structures of different expansion velocities. Such behavior is in agreement with the transient current recorded by a cylindrical Langmuir probe. Using the hydrodynamic model of scale relativity theory, the plasma dynamics at different time scales are numerically and analytically analyzed. #
Chaos, Solitons & Fractals, 2007
One obtain various interesting results if one introduces the hydrodynamic formulation of scale re... more One obtain various interesting results if one introduces the hydrodynamic formulation of scale relativity theory (SRT), for a coherent quantum fluid, into the time dependent Ginzburg-Landau (TDGL) equation, which describes superconductivity. The London gauge and the zero momentum of the Copper pairs (i.e. the London equations) arise naturally from the imaginary parts of the computed system. One obtains a particular relation between the diffusion coefficient, the (dimensionless) friction coefficient and the (dimensionless) Ginzburg-Landau parameter which yields a new natural gauge for the TDGL equation (as postulated by some authors). If the value of the real velocity of the Copper pairs tends to zero, the imaginary velocity of the pairs becomes real. The subquantum potential is proportional to the density of the Copper pairs. Moreover, under special circumstances, the superconductor acts as a subquantum medium energy accumulator. In this context, we discuss a certain special coherence of the Cooper-pairs by means of e (1) space-time (El Naschie's superconductivity).
revistadechimie.ro
Carbon nanotubes, long, thin cylinders of carbon, about 10.000 times thinner than a human hair, w... more Carbon nanotubes, long, thin cylinders of carbon, about 10.000 times thinner than a human hair, were discovered in 1991 by Sumio Iijima. These are large macromolecules that are unique for their size, shape, and remarkable physical properties. From chemical point of view, the ...
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Papers by Petrica Vizureanu