Influence of zinc substitution on structural, elastic, magnetic and optical properties of cobalt chromium ferrites

The polycrystalline Co1−xZnxCr0.5Fe1.5O4 series with (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) has been synthesized by conventional ceramic rout method. The structural and elastic properties have been investigated by X-ray diffractometer and Fourier transform spectroscopy. Both XRD and FTIR confirm the formation of single phase cubic spinel ferrites. The cationic distribution for all samples has been proposed. The lattice parameter, X-ray density, hoping length, bond length, and packing factors–in accompaniment with variations in the zinc concentration–have been studied. The IR band position has been explained by the cations involved in the structure. The elastic moduli such as Young's modulus, bulk modulus, rigidity modulus and Poison's ratio have bee calculated using force constants. Scanning electron microscope (SEM) observation conveys information about the agglomeration of particles. The hysteresis curve obtained from vibrating sample magneto meter (VSM) conveys information about the soft nature of prepared compositions. The saturation magnetization decreases with addition of zinc ions and coercivity is almost zero. An increase in band gap energy has been observed with addition of zinc by Ultraviolet Visible Spectroscopy (UV-VIS), which is due to small crystallite size.

RELATIVE PORE VOLUME UNDER INDENTATION OF POROUS MATERIALS

Investigation of the function of the relative volume of pores under the load action is carried out on the base of the solution of the static contact problem of the indentation of a layer made of a material with voids or unfilled pores. A rigid strip indenter with a flat base is pressed into a porous layer that is adhered to a non-deformable base along the lower boundary. The formulated 3D problem of the indentation of a porous layer is reduced to solving the plane contact problem of the indentation of a porous strip. The plane contact problem is reduced to solving an integral equation for unknown contact stresses, the solution of which is constructed by the method of successive approximations in the form of an asymptotic expansion in the dimensionless parameter of the problem. The obtained contact stresses and the force acting on the indenter made it possible to study the influence of the nonclassical moduli of the layer porous material (the connectivity modulus and pore rigidity modulus) on the main contact characteristics and on the distribution of the function of the relative pore volume. The connectivity modulus increase leads to an increase in the compliance of the layer porous material, the pore rigidity modulus increase leads to an increase in the rigidity of the layer porous material. The maximum value of the distribution function of the relative pore volume in the porous material of the layer is achieved under the indenter base centre, regardless of the change in the porous material non-classical moduli.

Evaluation of the measurement uncertainty of the stiffness modulus: test case of indirect tensile on cylindrical specimens

This study treats the measurement uncertainties that we can find in the stiffness modulus of the bituminous test. We present all the sensors installed on rigidity modulus measurement chains and also their uncertainty ranges. Several parameters influence the rigidity module's value, such as the parameters related to experimental conditions, and others are rather connected to the equipment's specification, which are the speed, the loading level, the temperature, the tested sample dimension, and the data acquisition, etc. All these factors have a great influence on the value of the modulus of rigidity. To qualify the uncertainty factors, we used two approaches: the first one is made by following the method described by the GUM (Guide to the expression of uncertainty in measurement), the second approach based on the numerical simulation of the Monte Carlo. The two results are then compared for an interval of confidence of 95%. The paper also shows the employment of the basic methods of statistical analysis, such as the Comparing of two variances. Essential concepts in measurement uncertainty have been compiled and the determination of the stiffness module parameters are discussed. It has been demonstrated that the biggest source of error in the stiffness modulus measuring process is the repeatability has a contribution of around 45.23%.

Recurrence Time Analysis of the 1883 (Mw 8.6 ~ 9.1) Paleo Megathrust Earthquake in West Bengkulu, Sumatra, Indonesia, Using Plate Kinematic Model for Supporting Mitigation Program

The great paleo-megathrust earthquake occurred in west Bengkulu-Sumatra on November 25, 1833 and it was estimated to have the magnitude of about Mw 8.6–9.1. This earthquake triggered a tsunami that has 3-4 m height in the Bengkulu coastal and its vicinity. The fundamental earthquake parameter was not known exactly, thus it was difficult to conduct the analysis. We tried to analyze it using scaling law relations of earthquake parameter and magnitude scenarios to estimate the recurrence time based on the plate kinematic model to support the long-term mitigation program. The recurrence time was estimated at 179 years, 250 years, and 314 years if the earthquake is assumed to have a dip-slip mechanism, plate slip rate about 7 cm/year, and magnitude scenarios of 8.6, 8.8, and 9.1 respectively. Then, the recurrence time was estimated at 314 years, 438 years, and 550 years respectively if the earthquake is assumed to have a plate slip rate about 4 cm/year. The other estimation was used the strain rate value of about 1.19 x 10-14/s for Sumatra region and the rigidity modulus of 3.1011 dyne/cm2. We found the recurrence estimation of about 161 years (Mw 8.6), 222 years (Mw 8.8), and 220 years (Mw 9.1) for the dip-slip model. Meanwhile, if this study used all rupture models, the recurrence time of the Bengkulu paleo megathrust earthquake would be about 370 years (Mw 8.6), 558 years (Mw 8.8), and 553 years (Mw 9.1).

Processing the Working Parts of Tools Used in Construction Industry Using High Energy Methods

This paper considers the effect of hardening of throwaway cutting inserts made of hard alloy T15K6 using continuous laser impact at various modes. Tests were carried outon inserts made of hard alloy T15K6. The cutting properties of the inserts were determined by cutting on a T612 vertical milling machine. A face mill with a diameter of 100 mm with mechanical mounting of tested inserts was used as a tool.Dry milling was performed using two inserts. At that, cutting mode was of impact natureas the mill diameter was larger than the width of machined workpiece. Number of passes – 5. Cutting modes:v = 197 m/min, h = 1 mm, S = 160 mm/min, b = 90 mm. Machiningwasperformedonworkpieces made of 40X grade steel (GOST 4543-71). Workpiecedimensions– 160x60x90 mm. During the machining, hard alloy inserts moved beyond the workpiece edge and cut into it from the other side. One of the main performance characteristics of hard alloys is material rigidity (modulus of elasticity, Е). Tests were carried out after various types of laser impact at bending and material rigidity was determined by strain gauging. Decreasein the slopeofstraight-lineportionofrelativestrain-versus-stress curve at bending indicates the decrease in hard alloys’ modulus of elasticity after laser processing. Small defect structure is being formed.

Composition Dependence of Elastic Moduli of Mixed Cobalt-Zinc Ferrites Prepared by Citrate Precursor Method

CoxZn1-xFe2O4 nanoparticles were prepared by chemical citrate precursor synthesis method. The Young’s modulus ‘E’ and the rigidity modulus ‘n’ of mixed cobalt-zinc ferrites have been determined by the ultrasonic pulse transmission technique at 1 MHz. The elastic modules of the ferrites were corrected to zero porosity using the formulae of Harselman and Fulrath. The observed variation of the elastic module with composition has been interpreted on the basis of binding forces between the atoms of the spinal lattice. A linear relationship between Debye temperature ØD and average sound velocity Vm has also been observed.

Mechanical and Dynamical Properties of High Performance Concrete Using Arecaceae Fiber

The purpose of this endeavor is to acquire learning for arranging the working with negligible exertion material (arecaceae fiber) using normal fibre.Because trademark fiber can be one possible material which are trashy and locally available.Among all regular fiber coir fiber are picked because of its most important malleability quality. The static direct of arecaceae fiber stronghold concrete essential part is in every practical sense cloud .In this work the effect of fiber content on properties of AFRC is considered. To survey the capability of coir fiber in improving the properties of the strong the first class of plain cement is used as reference. The mechanical properties, for instance, compressive quality , part rigidity, modulus of break and quick chloride entrance test were resolved for all ARFC and Plain Cement models. Likewise the fiber in appropriate sum should be selected.(i.e.,) fiber substance of 2% and 3% by weight of bond and having a length of 6.5cm are used to design AFRC

A Research on Kevlar and Hybrid Kevlar Composites; A Report

This study focused on the Kevlar fiber composite, the demand of Kevlar composites increasing day-byday because it’s light weight and good mechanical properties. There are different types of fiber composites are available like Carbon, Basalt, Glass, Jute, Kenaf, Flax, Hemp and Kevlar etc. Out of these available material Kevlar is one of the most favorable composite material. Properties of Kevlar include high rigidity modulus, toughness, thermal stability and most importantly strength. Moreover, the properties of Kevlar composite can be increased by applying the different hybridization and treatment process. The aim of this study, to explore the different types of hybridization and treatments that can be applied for improving the mechanical properties of Kevlar composite

STUDY ON ELASTIC DEFORMATION OF INTERSTITIAL ALLOY FeCWITH BCC STRUCTURE UNDER PRESSURE

The analytic expressions of the free energy, the mean nearest neighbor distance between two atoms, the elastic moduli such as the Young modulus E, the bulk modulus K, the rigidity modulus G and the elastic constants C11, C12, C44 for interstitial alloy AB with BCC structure under pressure are derived from the statistical moment method. The elastic deformations of main metal A is special case of elastic deformation for interstitial alloy AB. The theoretical results are applied to alloy FeC under pressure. The numerical results for this alloy are compared with the numerical results for main metal Fe and experiments.