The 10 most-cited articles in Advanced materials research, 2017

Perturbation method is used to resolve one-dimensional wave equation under the assumption of small strain conditions. The relationship of the second order relative nonlinear coefficients (SORNC) β', the third order relative nonlinear coefficient (TORNC) δ' as the functions of fundamental and harmonic amplitudes is determined. The specimens are loaded from-200 MPa to 320 MPa at increments of 40 MPa by the electron universal testing machines. The SORNC β' and TORNC δ' are detected by the nonlinear ultrasonic testing system when ultrasonic waves propagate in the specimens. Results show that the relative nonlinear coefficients increase with the stress. The SORNT β' is approximately linear with the stress when stress is lower than 84.6% of the yield strength. The TORNC δ' is approximately linear with the stress when stress is lower than 76.9% of the yield strength.

In previous work focused on using recycled concrete powder as cement replacement the basic dependency of the mechanical properties on the amount of recycled concrete powder was defined. Influence of the amount of recycled concrete powder on the flexural and compressive strength was shown on 0, 33, 67 and 100 wt. % cement replacement. Based on the previous data the strength properties of the cement paste with recycled concrete powder below 33 wt. % was almost constant and strength properties were comparable with reference sample made of cement only. After the recycled concrete powder in cement paste exceeded amount of 33 wt. % the flexural and compressive strength decrease rapidly. In case of 67 wt. % amount of recycled concrete powder the compressive strength decrease about 65 %. The aim of this article is define critical amount of recycled concrete powder in cement paste when strength properties start decrease rapidly and cement replacement is no longer beneficial. This critical amount will be located somewhere between 30 and 50 wt. % of recycled concrete powder. Replacement below…

The paper addresses the development of advanced welding technologies with two and three solid wires for joining of HSLA API-5l X70 (High-strength low-alloy) steel plates with thickness of 19.1 mm. The experiments were performed using a multi-wire Submerged Arc Welding (SAW) system that was developed for welding of steels with solid, tubular and cold wires, in different combinations. The main goal of the research was to assess the mechanical performances of the welded joints achieved by multi-wire SAW technology and then to compare them with the single wire variant, as reference system. The welded samples were firstly subjected to NDT control by examinations with liquid penetrant, magnetic particle, ultrasonic and gamma radiation, with the aim of detecting the specimens with flaws and afterwards to reconsider and redesign the corresponding Welding Procedure Specifications (WPS). The defect-free welded samples were subjected to tensile, Charpy V-notch impact and bending testing in order to analyse and report the mechanical behaviour of API-5l X70 steel during multi-wire SAW process.…

Oxide semiconductors have attracted increasing interest due to their potential in solving environmental problems. ZnO-based nanoparticles (NPs) are among the most investigated for efficient disinfection and microbial control.Iron-doped zinc oxide nanoparticles (Fe:ZnO NPs) were successfully fabricated through precipitation method at low temperature followed by thermal treatment. The obtained Fe:ZnO NPs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and ultraviolet-visible (UV–Vis) spectroscopy. The effect of iron content on structural, morphological, antimicrobial and photocatalytic properties was investigated and discussed.The photocatalytic activity of the nanoparticles was tested by degradation of methylene blue (MB) solution under UV light for 60 min irradiation. The antibacterial activity was determined by paper disc method on Mueller-Hinton agar against the Gram-negative bacteria Escherichia coli (E. coli) and the Gram-positive bacteria Staphylococcus aureus (S. aureus) and compared to that of the undoped ZnO NPs. Consistent improvement on…

The BaFe12O19 nanoparticles was prepared by sol-gel method in different temperature (750°C,850°Cand 950°C), and then BaFe12O19/polyaniline nanocomposites was synthesized by in situ polymerization. The XRD, FTIR spectra, SEM and vector network analyzer were used to analyze the "" chemical component, morphology and microwave absorption property of the nanocomposites. The result show that BaFe12O19 can be generated at 750°C without any impurity ,and its size increased with increase of calcination temperature.BaFe12O19 nanoparticle was coated with polyaniline partially, and we can get it have interaction with polyaniline through FTIR spectra. While the ferrite calcined at 850°C,the thickness of the absorbing material is 4.5mm,the nanocomposites have the largest reflection loss of-17.6 dB at 6 GHz,and its reflection loss values less than−10 dB in the range of 5-7.4GHz.

In this work, crystal structure, magnetic properties and magnetocaloric effect of Nd0.7Gd0.3Mn2Si2 alloy were studied by X-ray diffraction (XRD), Physical Property Measurement System (PPMS) and Differential Scanning Calorimetry (DSC). Nd0.7Gd0.3Mn2Si2 crystallizes in ThCr2Si2-typed structure with space group I4/mmm, in which the Nd, Gd, Mn and Si atoms occupy 2a (0, 0, 0), 2a (0, 0, 0), 4d (0, 1/2, 1/4) and 4e (0, 0, 0.38261) position, respectively. The Curie temperature (Tc) of Nd0.7Gd0.3Mn2Si2 alloy is 42 K, while the spin reorientation temperature (TSR) is 26 K and the Nel temperature (TN) is 410 K. The Tc and TN were determined using PPMS and DSC, respectively. The maximum value of the magnetic entropy change (-Smax) in the field change of 0-5 T is 11.862 J/kg K, while the value of relative cooling power (RCP) in Nd0.7Gd0.3Mn2Si2 alloy is 69.666 J/kg under the field change of 5 T.

In this paper the influence cell honeycomb geometry on the mechanical behaviour of a composite sandwich plate is analyzed. Three cell geometries (circular, hexagonal and square) are static analysed so that to select the best type of honeycomb that will be used in the manufacturing the sandwich plate core. The main aim is to develop approach models of equivalent orthotropic materials to replace the real model of honeycomb core with their properties so that to quickly calculate the sandwich plate made out of composite when is used a finite element analysis code. Geometry and material properties of the honeycomb are delivered by the material provider. Comparative analysis, by using Finite element analysis is performed for all geometries, in the same boundary conditions. Since in the impact loading of the composite sandwich plate the core is mainly loaded to compression, comparative study of the three cell geometries honeycomb was performed for this type of compressive loading. Since the cell is the basic element of the honeycomb core, the calculus is performed for one unit volume of…

In this paper it is presented the microstructure and wear resistance of FeNiCrMnCu high entropy alloy. High entropy alloys are composed by at least five metallic elements in equimolar or non-equimolare proportions. High entropy alloys a brand new category of metallic materials, appeared to be a new effort in materials science and engineering, which attracted great interest. To obtain FeNiCrMnCu high entropy alloy we used an 8000 Hz induction furnace. The chemical composition was determined by EDAX. Microstructural analysis was performed using optical microscopy and SEM (scanning electron microscopy), which showed that the FeNiCrMnCu high entropy alloy has a dentritic structure and form a solid solution. Choosing copper as the main element (copper tends to segregate in interdentritic region due to its positive enthalpy of mixing with many common elements) [1], along with the iron, nickel, chromium and manganese, led to obtaining a dentritic structure specify for solid solution, which, however, did not lead to a significant hardness for FeNiCrMnCu high entropy alloy. In this work we…

The paper presents some aspects regarding the wetting conditions in aluminium – graphite composite. The wettability depends on several factors like the presence of the oxide skin at the melt surface, formation Al4C3 at the interface between Al and particles, temperature, pressure etc. In this paper, the conditions of perfect wettability of carbon by molten Al achieved under MCl–K2TiF6 molten salts (fluxes), alloying of the melt with surface active elements, heat treatment of reinforcement material and coating of the particles with a metallic thin layer.

Clay is a traditional construction material which has got to background with introduction of modern materials to building practice. There is not proper material available for clay constructions design due to a lack of proper examination of its mechanical properties. This article focuses on tensile bending strength of rammed earth. The mechanical properties depend on the amount of mixture water and on the amount and type of clay minerals. The clay minerals play role of the binder similarly like a cement in concrete. This paper is focused on the tensile bending strength and its dependence on the composition and quantity of clay mineral and its dependence on the amount of mixture water. Five earth mixtures were tested. Mechanical properties were examined on small test bodies made of these mixtures. The mechanical properties of the five mixtures are compared at the end of the paper.