CRTI Library

Contrôle du joint de soudure d’un pipeline par ultrasons

In this study, we have been adapted to the various techniques of non-destructive testing and especially non-destructive ultrasonic testing by contact of a piezoelectric transducer with welded parts (welded pipe). This method can detect, locate, dimension and identify defects in the weld seam after going through several steps such as calibration and tracing of the distance amplitude curve. The ultimate goal of this control is to accept or reject controlled parts according to international standards Voir les détails

Mots clés : Non-Destructive testing, - ultrasonic testing, welded pipe

Prediction of the Friction Coefficient of 13Cr5Ni2Mo Steel Using Experiments Plans-Study of Wear Behavior

Metal materials used in industrial applications deteriorate under the effect mechanical and chemical phenomena occurring under operating conditions, such as pipes carrying gas or fluid that are subject to internal wall wear. From where an experimental study was conducted through friction tests on supermartensitic stainless steel Cr13Ni5Mo2, in order to estimate the effect of test parameters on friction coefficient and wear behavior of this steel by adopting the factorial plans 22 methodology at two factors (Load "P" and linear sliding "V"), each at two levels (-1, +1). The results have been demonstrated using a mathematical model predicting the coefficient of friction "f" in every point of the study field. The factorial plans make it possible to establish a modeling of the studied phenomenon with a maximum of efficiency and a minimum of experiences. The experimental results showed that the friction coefficient "f" reaches a max value for an applied load P=10N combined with a linear speed V=5cm/s. In addition, the wear morphology of surfaces after the friction test indicates that for 2N and at all speeds, friction is dominated by an abrasive wear mechanism. However, for 10N, it is observed the predominance of adhesive wear with a higher wear rate. Voir les détails

Mots clés : friction, factorial design, Mathematical model, wear mechanism

Synthesis and characterization of hydroxyapatite powder derived of eggshell by precipitation method

Hydroxyapatite is the inorganic material with formula Ca10(PO4)6(OH)2. It is one of bioceramic was used for one repairs, fixing defects of filing voids in biomedical fields. The use of chicken eggshell is one of the natural sources to obtain the calcium phosphate compounds. The main objective of this study is to synthesize the hydroxyapatite by precipitation method from eggshell. The raw eggshell was calcined at 850°C for 2 hours following by grinding for 16 hours. The HA powder was synthesized by wet chemical method, using eggshells and phosphoric acid (H3PO4). X-ray diffraction spectroscopy (XRD, Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR) were used to characterize the morphology, composition and distribution of the particles. The Thermos gravimetric analysis (TGA-DTA) was also carried out to evaluate the stability of the synthesized HA powder. The particle-size distribution (PSD) of the powder was determined by the laser scattering particle size distribution analyzer. The results showed that the sintered at 1000°C of HA powder resembles the feature of pure and single apatite phase having favorable Ca/P ratio. Voir les détails

Mots clés : hydroxyapatite, Bioceramics, synthesis, Eggshell, Precipitation

Preparation and characteristics of synthesized hydroxyapatite from bovine bones and by co-precipitation method

Hydroxyapatite (HA, (Ca10(PO4)6(OH)2) is a widely studied bioceramic due to its biocompatibility, bioactivity, and chemical similarity to the mineral component of bone. Generally, hydroxyapatite can be made from several natural and synthetic sources.The objective of this study is to prepare hydroxyapatite powders from different precursors (natural or chemical). Hydroxyapatite was synthetized by Co-precipitation method, the chemical precursors of which are [Ca(NO3)2.4H2O, (NH4)2HPO4] and the natural source was bovine bone. Bovine hydroxyapatite (BHA) was extracted from the bovine bone bio-waste via thermal method and milling process. Synthesized HA (SHA) was prepared by co-precipitation method with the pH 10.0 of mother liquor. The prepared powders were characterized using various analytical techniques such as XRD, FTIR spectroscopy, thermogravimetry (ATG), and scanning electron microscope (SEM). These techniques provide information about the structural, chemical, morphological and physicochemical of each of the prepared powders. The use of co-precipitation method produced a low crystallinity of HA while the thermal method increased crystallinity. On the other hand, the results showed that the Ca / P ratio of synthetic hydroxyapatite (SHA) as well as that of bovine bone source (BHA) was also stoichiometric. Voir les détails

Mots clés : hydroxyapatite, Bovine bone, synthesis, Co-precipitation.

Structural, Magnetic, Dielectric and Piezoelectric Properties of Multiferroic PbTi_1−xFe_xO_3−δ Ceramics

PbTi_1−xFexO_3−δ (x = 0, 0.3, 0.5, and 0.7) ceramics were prepared using the classical solid-state reaction method. The investigated system presented properties that were derived from composition, microstructure, and oxygen deficiency. The phase investigations indicated that all of the samples were well crystallized, and the formation of a cubic structure with small traces of impurities was promoted, in addition to a tetragonal structure, as Fe³⁺ concentration increased. The scanning electron microscopy (SEM) images for PbTi1−xFe_xO_3−δ ceramics revealed microstructures that were inhomogeneous with an intergranular porosity. The dielectric permittivity increased systematically with Fe³⁺ concentration, increasing up to x = 0.7. A complex impedance analysis revealed the presence of multiple semicircles in the spectra, demonstrating a local electrical inhomogeneity due the different microstructures and amounts of oxygen vacancies distributed within the sample. The increase of the substitution with Fe³⁺ ions onto Ti⁴⁺ sites led to the improvement of the magnetic properties due to the gradual increase in the interactions between Fe³⁺ ions, which were mediated by the presence of oxygen vacancies. The PbTi_1−xFe_xO_3−δ became a multifunctional system with reasonable dielectric, piezoelectric, and magnetic characteristics, making it suitable for application in magnetoelectric devices. Voir les détails

Mots clés : dielectric response, Fe-doped PbTiO3, Magnetic Properties, multiferroic ceramics, piezo- electric properties

Étude et réalisation de structure pérovskite non stœchiométrique PbTiO_3-δ pour des applications ferroélectrique. 

Dans ce travail de recherche, nous avons élaboré le matériau PbTiO_3-δ à partir les oxydes PbO et Ti₃O₅ en utilisant  la technique réaction à l’état solide dans un four sous vide. Dans ce travail nous avons étudié trois paramètres, le premier c’est l’effet de la température de calcination sur les propriétés structural (DRX, FTIR, RAMAN, EDX), microstructural (MEB) et magnétique (VSM) de PbTiO_3-δ et étudié les propriétés diélectrique (pont d’impédance) de matériau élaboré. Dans l’objectif d’amélioration des propriétés magnétique de PbTiO_3-δ, dans la deuxième partie nous avons dopé le PT avec un matériau ferromagnétique Fe d’où nous avons varié la quantité de dopant Fe et étudié l’effet de dopage sur les diffèrent propriété structural, microstructural, diélectriques et magnétiques. Dans la troisième partie nous avons étudié l’effet de la pression de vide de calcination sur les différentes propriétés structurales, microstructural, diélectriques et magnétiques de PbTiO_3-δ élaboré par la technique réaction à l’état solide. Voir les détails

Mots clés : PbTiO3-δ, Pérovskite, Lacune d’oxygène, Aditifs, DRX, MEB, Raman, Echographies ultrasonore, Relaxeur

Magnetic and structural Behavior of Fe-CoO NanocompositesMechanically Milled

The Fe60(CoO)40 nanostructured alloys have been prepared from pure iron and cobaltoxide powders by mechanical alloying technique within a high energy planetary ball-mill.Morphology, microstructural and magnetic properties of this powder were investigated by a Scanning Electron Microscope (SEM), X-ray diffraction (XRD) and Vibrating sample magnetometer (VSM). The effect of time of milling on magnetic behaviour of Fe(CoO) nanostructured composite has been investigated. Apparition of new phase polycrystallinesample having a size in the range of 12 and 26 nm, it is confirmed by X-ray diffraction testing.The enhanced magnetic properties and structural behaviour of the nanoparticle are due by the diminution of size of crystallite. After 40 hours of milling, the appearance of spinel structureof CoFe2O4. The reduction in particle size leads to a significant increase in magnetic hardening, the coercive field at room temperature increases from 6 Oe to 208 Oe Voir les détails

Mots clés : FeCoO nanostructured, Magnetic Properties

The influence of vacuum pressure on the electrical properties of PbTiO_3-δ ceramics

PbTiO_3-δ ceramics were successfully prepared by the traditional solid state reaction method using different vacuum pressures during calcinations step and then sintered at 1150 °C/2h. The present study was focused on the influence of vacuum pressure variation on the electrical properties of PbTiO^3-δ ceramics. The room temperature XRD patterns indicate the crystallization of the perovskite structure for all the ceramics. The dielectric permittivity is increasing with decreasing of vacuum pressure due to the increasing of oxygen vacancies with reaching the high vacuum. Resistivity decreased with temperature increasing which proves the semiconductor character of present PbTiO_3-δ ceramics. The electrical characterization indicates that PbTiO_3-δ ceramics prepared using three different vacuum pressures during calcinations step are suitable for room temperature applications in microelectronics. Voir les détails

Mots clés : PbTiO3-δ ceramics, vacuum pressure, oxygen vacancies, Electrical properties, resistivity

Étude et réalisation de structure pérovskite non stœchiométrique PbTiO_3-δ pour des applications ferroélectriques

Dans ce travail de recherche, nous avons élaboré le matériau PbTiO_3-δ à partir les oxydes PbO et Ti₃O₅ en utilisant  la technique réaction à l’état solide dans un four sous vide. Dans ce travail nous avons étudié trois paramètres, le premier c’est l’effet de la température de calcination sur les propriétés structural (DRX, FTIR, RAMAN, EDX), microstructural (MEB) et magnétique (VSM) de PbTiO_3-δ et étudié les propriétés diélectrique (pont d’impédance) de matériau élaboré. Dans l’objectif d’amélioration des propriétés magnétique de PbTiO_3-δ, dans la deuxième partie nous avons dopé le PT avec un matériau ferromagnétique Fe d’où nous avons varié la quantité de dopant Fe et étudié l’effet de dopage sur les diffèrent propriété structural, microstructural, diélectriques et magnétiques. Dans la troisième partie nous avons étudié l’effet de la pression de vide de calcination sur les différentes propriétés structurales, microstructural, diélectriques et magnétiques de PbTiO_3-δ élaboré par la technique réaction à l’état solide Voir les détails

Mots clés : PbTiO3-δ, Pérovskite, Lacune d’oxygène, Aditifs, DRX, MEB, Raman, Echographies ultrasonore, Relaxeur.

Mechanical and structural behaviour of TiAlV nanocrystalline elaborated bymechanical milling technique

The aim of this study is to fabricate the Ti50Al40X1 0 nanostructured alloy (X: V) from pure titanium,aluminium, and vanadium powders by using a high-energy planetary ball mill with increasingmilling time from 10 to 80 h. Morphology, structural, and mechanical properties of this alloy wereinvestigated by a SEM, XRD, and nano-indentation testing. The effect of milling time on structural,morphological, and mechanical properties has been investigated. Microstructural characterisationshowed a decrease of average particle size during milling time. Crystallite size decreased from 49to 6.02 nm and lattice strain increased from 0.15% to about 0.89% during mechanical alloying. Inaddition, the mechanical properties of Ti50Al40V1 0 nanostructured materials were stronglydepended on the microstructure and crystallite size of new phases that appear during mechanicalmilling. Microhardness of the Ti50Al40V1 0 alloy increases with milling time from 261 to 738 Hv.These changes could be attributed to the crystallite size and the strain variations during milling. Voir les détails

Mots clés : crystal microstructure, Mechanical milling, Microstructural properties, nanostructured alloy, hardness testing