Defect and Diffusion Forum Vol. 406

Abstract: Through this research we have prepared samples of glass, which includes 60 mol%B₂O₃ – x mol %barite – (40-x) mol %Li₂O, where x= 5, 7.5, 10, and 15 mol%. The samples fabricated by the melt quenching technique. The samples are melted in alumina crucible at 1473 K for 1.5 h in an electric muffle furnace (LENTON). The glasses were casted into stainless molds, and then immediately transferred to an annealing furnance at about 400°C. The aim of this work is to determine the extent of the effect of raw barite on the physical and optical properties of this glass. The optical transmittance and reflectance spectrum of the glasses in this work were determined in the wavelength range 300–2500 nm at room temperature. The physical and optical properties of the following prepared glass samples have been determined and calculated (density, volume molar, refraction index, Optical dielectric constant, molar refractivity and electronic polarizability) for glasses prepared.

Abstract: This work is a contribution in analyzing structure, tribological behavior and corrosion of AISI L6 hardened tool steel. Structural characterization and tribological behavior of steel were investigated using Optical Microscopy (OM), Scanning electron microscopy (SEM), wear testing by friction on a pin-on-disc Tribometer and corrosion by potentiodynamic polarization. Comparing to the as-received steel, hardening has generated a fine martensitic microstructure causing a 1.5 times hardness increase. Hardening has contributed to improvement of wear resistance as the coefficient of friction has decreased from 0.86 to 0.67μ. An increase in corrosion resistance was observed after hardening treatment.

Abstract: In this study, the adsorption of copper Cu (II) from aqueous solution, on Tamanrasset’s clay which is low cost adsorbent, was studied using batch experiments. The adsorption study includes both equilibrium adsorption isotherms and kinetics. The characterization of the adsorbent necessitated several methods such as X-Ray Diffraction, Scanning Electron Microscopy coupled with Energy Dispersive X-ray, BET for specific surface area determination, Fourier transform infrared spectroscopy and thermogravimetric analysis. Indeed, various parameters were investigated such as contact time, initial metal ion concentration, mass of solid, pH of the solution and temperature. The adsorption process as batch study was investigated under the previews experimental parameters. The results revealed that the adsorption capacity of Cu²⁺ is maximized at naturel pH of metal 5.5. Removal of copper by the clay of Tamanrasset (kaolinite) achieved equilibrium within 50 minutes; the results obtained were found to be fitted by the pseudo-second order kinetics model. The equilibrium process was well described by the Langmuir model and the maximum adsorption capacity was found to be 26.59 mg/g.

Abstract: In the last decade, several phenomenological yield criteria for anisotropic material has been proposed to improve the modeling predictions about sheet metal-forming processes. In regard to this engineering application, two proprieties of models have been used. If the yield function and the plastic potential are not same (not equal), the normality rule is non associative flow rule (NAFR), otherwise, when the stresses yield has been completely coupled to the anisotropic strain rate ratio (plastic potential), is called the associated flow rule (AFR). The non-associated flow rule is largely adopted to predict a plastic behavior for metal forming, accurately about à strong mechanical anisotropy presents in sheet metal forming processes. However, various studies described the limits of the AFR concept in dealing with highly anisotropic materials. In this study, the quadratic Hill1948 yield criteria is considered to predict mechanical behavior under AFR and NAFR approach. Experiment and modeling predictions behaviour of normalized anisotropic coefficient r (θ) and σ (θ) evolved with θ in sheet plane. and the equibiaxial yield stress σ_b was assumed σ_b=1 but the r_b-values was computed from Yld96 [15].

Abstract: Dolomite is one of the commonest minerals that abound in the formation of a number of geological conditions. And it is found in abundance in eastern Algeria, especially Ain Mlila-Wilaya of Oum El Bouaghi-Algeria. The analyzed sample of raw dolomite has been by various physical-chemical techniques. The constituents of these carbonates are Ca, Mg, C, O, Al, Si, Fe, Ba, F, and Sr, analysis by XRD, and Raman, show that in addition to CaMg(CO₃)₂, we may have calcium carbonate. The Photoluminescence analysis characterizes the intrinsic and extrinsic defects of this carbonate. Differential thermal analysis reveals the different transformations of this mineral during heating. Indeed several stages including the elimination of water, the departure of CO₂, the formation of MgO, and finally the formation of CaO.

Abstract: In the field of economic and ecological material research which can replace the composite material currently used in several fields such as glass wool, research leads to a comparison of the mechanical properties and the quality of plates made from recycled materials with those of glass wool, in particular in terms of surface condition and geometric precision thus. In this study, we recycled and used damaged wool fibers in a composite material; the results showed that the new product has mechanical characteristics similar to those of fiberglass composite materials. The recycling of wool fiber reduces the cost of a product made of composite materials, with the possibility of a later study of the machinability of the plates made from this material and its use in various sectors.

Abstract: This study was mainly oriented on the evolution of the crystallographic texture as a function of the deformation resulting from the industrial wire drawing process. This, in fact, will make it possible to establish a relationship between the microstructure and the crystallographic texture in the medium carbon steel wires obtained by industrial wire drawing process and used in the manufacture of spring mattresses in order to minimize the loss of material and to satisfy the users of this product.During this study, a medium-carbon steel wires was characterized by two analytical techniques. The scanning electron microscopy (SEM) to monitor the microstructure evolution and the electron backscatter diffraction (EBSD) for the crystallographic texture analysis. The EBSD results are processed with OIM (Orientation Imaging Microscopy) analysis software.

Abstract: The main objective of this work is to highlight the influence of jute woven layer orientation on fracture parameters (energy release rate and stress intensity factor) of a polymer concrete laminate. The use of plant fibers, jute in this study, as reinforcements outside the polymer concrete, acquires mechanical properties, traction, and flexion, more than appreciable, however, other characteristics must be studied to ensure better integration on the market. The addition of plant fibers with different orientations is not without consequences on the mechanical behavior, in this case, on the resistance to cracking and its propagation. Fibered concretes have a very different behavior compared to non-fiber concretes, especially after the first cracking, where the fibers make their contribution by trying to stop the evolution and the propagation of micro-cracks within the matrix by making the concrete more ductile.

Abstract: Cement and alluvial sand are very essential materials in concrete preparation. The first material production contributes to the emissions of greenhouse gases, in particular carbon dioxide (CO₂), and the extensive exploitation of second material constitutes a danger on the extinction of its deposits. The use of waste glass powder (WGP) to partially replace cement and dune sand as a replacement for a small amount of alluvial sand appears as a potential solution that solves several problems at once (disposal of glass waste, reduction of emissions gas and preservation of construction sand deposits). The objective of this study is to verify the effects of these partial replacements on concrete properties, their cost, and the CO₂ emission reduction in the atmosphere. For this, three types of concrete are prepared: a control (0% of WGP); mixture 1 (10% WGP); and mixture 2 (20% WGP). In all three types, 5% of alluvial sand is replaced by dune sand. Obtained results show that these partial replacements do not affect the porosity (less than 20%), they give good indices as to the speed of sound propagation in the concrete (up to 3500 m/s), especially for the case of the second mixture after 56 days but this does not increase the concrete performance concerning compressive strength and performance of concrete with glass is less than that of control concrete. Economically, the reduction of 10% in cement saves 5 € per ton and environmentally, it reduces the emission of CO₂ from cement industry by 0.5 to 0.7% of total anthropogenic CO₂ emissions.