Table of contents

PREFACE

F Potecasu, G Gurau*, M Busila

¹Faculty of Engineering "Dunărea de Jos" University of Galati, Domnească Street, 47, RO-800008, Galati, Romania

gheorghe.gurau@ugal.ro

Abstract. This issue constitutes the Proceedings of the 8th International Conference on Material Science & Engineering, UGALMAT 2018. The conference, held October 11-13 2018 in Galati Romania, was organized by "Dunărea de Jos" University of Galati, Faculty of Engineering, Department of Materials Science and Engineering.

1. Preface to the UGALMAT 2018 Proceedings

UGALMAT is a traditional conference in the Romanian scientific landscape focused on advanced materials and technologies, nanomaterials and nanotechnologies. UGALMAT 2018 is in the eighth of the UGALMAT series; the first UGALMAT having been organised over sixteen years ago by the Department of Materials Science and Engineering, "Dunărea de Jos" University of Galati.

The aims of UGALMAT 2018 are to provide a platform for scientists, professors, research scholars and students, as well as industrial professionals to present their research in the filed of materials science, to exchange new ideas and to establish new relations for future collaboration.

UGALMAT 2018 was attended by over 100 delegates, including outstanding scientists, as well as young researchers from representative universities and research institutes from Romania, Europe and Asia who presented 96 scientific research works involving more than 300 authors. The scientific program consisted of 4 plenary lectures, 35 oral presentations and 57 poster presentations on the three symposia: ADVANCED MATERIALS AND TECHNOLOGIES (TMA 2018), CASTING, FROM TECHNIQUE RIGORS TO ART (ARTCAST 2018) and UGALNano8.

The present edition of the UGALMAT 2018 proceedings includes 28 papers accepted after careful peer-review processing of the submitted manuscripts. The selected papers present the newest findings related to metals and alloys, composite materials and structures, surface processes and surface characterization, mathematical modelling of material processing and material properties. Other papers address research topics in advanced materials such as thin films and submicron memory alloys.

We would like to thank the Scientific and Honorary Committee for their valuable assistance in organizing the scientific program. We would also like to thank the referees for their work which contributed to the high scientific standard of this issue of IOP Conference Series: Materials Science and Engineering.

We acknowledge financial support offered by ours sponsors: "Dunărea de Jos" University of Galati, ArcelorMittal Galaţi, Bureau Veritas România, S.C. Myosotis S.R.L. Galaţi, S.C. Company Med S.R.L. Galati, S.C. Rulmenţi S.A. Bârlad and S.C. Iprolam S.A. Bucureşti.

Finally, we would like to express our gratitude to all members of the Organizing Committee for their involvement and permanent availability to solve all the details of the conference.

Editors of UGALMAT 2018

Prof. Florentina Potecasu

Assoc. Prof. Gheorghe Gurau

Assist. Prof. Mariana Busila

"Dunărea de Jos" University of Galati, October 2018

All papers published in this volume of IOP Conference Series: Materials Science and Engineering have been peer reviewed through processes administered by the proceedings Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

Our proposal for this paper is to diversify the architecture of neural networks in order to optimize it and to obtain the best performing configurations that minimize errors of predictive mechanical properties of polymeric concrete. In this paper different architectures of artificial neural networks will be used for investigating the flexural strength of polymer concrete with fly ash and fibres. In the present study the epoxy resin was used for binding the aggregates. In the composition were introduced near the fly ash, used as filler, the cellulose fibres for improving the properties. The characteristics of these artificial neural networks architectures will be presented and analysed in order to choose the one that minimizes the prediction errors of the mechanical characteristics of polymer concrete and presents an optimal configuration that allows a high working speed that can adapt to this type of approaching the problem with a strong nonlinear character. By using this modern predictive methods, it was attempted to highlight its basic character - learning by examples specific to the human brain but much more efficient due to the mathematical models of the activation functions and the interconnection between the layers of neurons that exponentially increase their ability to adapt to strong nonlinear phenomena. Thus one can say that such a prediction helps to reduce the number of real experiences and can greatly contribute to obtaining the optimal configuration of parameters necessary to obtain a desired mechanical characteristic of the analysed concrete.

This paper presents a modern electric heat treatment which has implemented an electric furnace control system through thermoregulatory with PID control laws. An important aspect is the development of a mathematical model for controlling electrical heating systems for heat treatments based on mathematical modelling to predict the mechanical properties and structure of the play resulting from heat treatment. Validation of the experimental research of heat treatment designed by the mathematical model for predicting mechanical properties and structure of the finished part and model for controlling electrical heating system based on PID adjustment algorithms consists in structural analysis to determine the chemical composition, structural analysis by light microscopy, electron microscopy SEM and EDX quantitative analysis, determination of hardness alloys and physical and mechanical of the turbine blades component of a plasma torch on hydrogen made of heat-treated steel.

The paper presents the preparation of ZnO - SiO₂ nanocomposite coatings by successive layers deposition using sol-gel method, dip-coating technique. The influence of the drawing speed and number of layers on the film morphology, optical properties and corrosion resistance were monitored. It has been found that the increase in drawing speed and the number of layers results in an increased film thickness and a modified film morphology by spherical restructuring. The films deposited on a glass substrate have a transparency ranging from 45-90% in the VIS-NIR range depending on the film thickness. In the case of non-transparent substrates, it has been found that these films diminish the reflectivity due to the surface morphology and the presence of ZnO nanoparticles that absorb some of the light radiation. The corrosion test has showed that all of the deposited films provide superior protection to the substrates.

The paper analyses the effects of heat treatment (HT) and mechanical alloying (MA) on the evolution of phase structure of an Fe-Mn-Si-Cr-Ni Shape Memory Alloy (SMA) obtained by powder metallurgy (PM). Using various amounts of mechanically alloyed (MA'ed) powders, namely 0 and 40 vol. %, two groups of specimens with chemical composition Fe-14Mn-6Si-9Cr-5Ni (mass.%) were produced by PM. After blending, pressing, sintering and hot-rolling, each set of samples was subjected to five different heat treatment temperatures 973, 1073, and 1373 K, respectively. Tensile pre-straining tests were performed on all samples, with increasing pre-straining degrees up to 4.5 %, in order to stress-induce ε (hcp) martensitic phase in the material. Structural analysis was implemented by means of X-ray diffraction and SEM observations. XRD and SEM investigations revealed the formation of thermally induced α'-bcc martensite, besides ε-hcp, as a particularity of this powder metallurgy, mechanically alloyed, shape memory alloy.

Circulating tumor cells (CTCs) are cells present in the blood stream during the metastasis process. They can originate from primary or secondary tumors. Circulating tumor cells can be used for early diagnosis or they can be used for prognosis evaluation and even treatment efficiency evaluation. Circulating tumor cells can be captured based on specific antigens found on their surface that differ from those of normal blood cells, they can be captured using specific electrical signatures using dielectrophoresis and they can also be captured using induced magnetic properties and magnetophoresis. In this paper we describe a method for synthesizing and functionalizing superparamagnetic nanoparticles. The nanoparticles will be covered with polyethylenglicol (PEG) molecules to reduce agglomeration and non-specific cell adhesion or blood proteins fouling. The PEG covered magnetic nanoparticles will be functionalized with anti-EpCAM antibodies that are going to make the nanoparticles specifically bind to CTCs present in the blood sample. The samples will be further processed in a microfluidic device that will separate the targeted cells through magnetophoresis.

A real necessity in the field of materials engineering and beyond is the development of new smart materials that effectively combine state-of-the-art technology with competitive costs to meet current technical requirements and challenges. In our days, fluids used in engineering occupy a significant place, and for their application in the industry, special thermophysical, thermal and chemical properties are required. Nanofluids are new fluids that contains nanometric particles, called nanoparticles. Traditional fluids used for nanofluids are water, oil and ethylene glycol, and nanoparticles are typically made of metal oxides, carbides or carbon nanotubes. Ionanofluids, on the other hand, are new heat transfer fluids based on ionic liquids, with superior thermal properties compared to the conventional fluid. Ionanofluids are recently developed by adding nanomaterial particles to an already novel fluid, as the ionic liquid. From the available literature, it is easy to understand that a new heat transfer fluid should have good thermal and flow properties and the iononofluids thermophysical properties can be improved by juggling with the amount and type of nanoparticles added in the ionic liquid. The goal of ionanofluids development is to obtain the highest possible thermal properties at the lowest possible concentrations, thus this paper aims to experimentally study the specific heat of these new nanoparticle enhanced fluids.

The purpose of this study was to assess the changes induced by pressure-assisted thermal processing (PATP) treatment in two multilayer polymer films used as packaging material by the meat industry. The changes induced by the treatment at 600 MPa, 70 ºC for 10 minutes on the structural, mechanical and thermal properties of two multilayer polymer films (Pev-70 coextruded high barrier multilayer film with the structure PA / EVOH / PA / PE and Pob-60 combination of biaxially oriented polyamide with a co-extruded barrier film of the polyethylene / EVOH / m-polyethylene structure) were studied. Numerous changes induced by the PATP treatment on the structural, mechanical and thermal properties of the two multi-layered polymer films used as packaging materials in the meat industry have been identified. The choice of a packaging material according to the PATP treatment requires a better understanding of all the changes induced by this treatment. So, this study has preliminarily identified a part of those changes that occurs and could irreversible affect the quality of foods.

The connecting rod along with the crankshaft turn the translation movement of the piston into rotation. The alternating forces acting on the connecting rod caused micro-fissures, resulting in materials breaking at much lower forces than the maximum allowable stress. This work presents the finite element analysis to determine the fatigue strength of the connecting rod. The results of the study show the dependence of fatigue resistance on the configuration of the connecting rod processing surface for the two types of the steel being analysed.

Latterly, it is of interest to enhance combination of strength and toughness of steel for advanced products, therefor the objective of this research is to improve the mechanical properties of high strength low - or ultra - low alloy (HSLA) steels through grain refinement. The ultra-fine grained S420NL steel were produced by high speed high pressure torsion (HSHPT) at room temperature. This severe plastic deformation method was chosen because it is one of the most feasible and rapid ways for nanostructuring various metallic materials down to ultrafine grain range. The procedure key parameters of deformation are described in detail in the paper. The influence of severe plastic deformation applied in cast state steel on microstructure changes and deformation behaviour was investigated. Optical microscopy, SEM and energy dispersive x-ray spectroscopy (EDX) analysis carried out on the samples revealed that severe plastic deformation led to the subsequent formation of an ultrafine-grained microstructure. Sample hardness increased rapidly with progress of torsion deformation degree.

Magnesium alloy, as biodegradable material, are attracted increasing interest in the field of bone graft substitution due to their excellent biocompatibility and good corrosion resistance. The main clinical challenges of ZK60 Mg alloy remain requirements such as: straight, fracture resistance, work hardening mechanical shock and so on, concomitant with plasticity. According to the Hall-Petch theory, an effectively enhance strength of Mg alloys may be realized by grain refinement. This paper proposes a reliable approach to fabricate Mg cast alloys down to ultrafine-grain range within just a few seconds. Ultrafine grained (UFG) Mg alloy was produced by severe plastic deformation (SPD), using high speed high pressure torsion (HSHPT) procedures. The microstructure evolution of the as-cast and as-severely deformed Mg-Zn-Zr was characterized using electron microscopy and energy dispersive spectroscopy (EDX). X-ray diffraction analyses (XRD) was performed to study the impact of severe plastic deformation on internal structure changes. Micro hardness tests indicated significant increase with the progression of true strain. Results so far have been very encouraging in developing new solution for biodegradable applications.

The goal of the present paper is to analyze the porosity in some powder metallurgy (P/M) alloys by two different methods, using the conventional method and by image processing analysis method. Quantitative image processing is a new and useful tool which is able to determine the pore size, pore size distribution and porosity of parts obtained by P/M route. One important and significant disadvantage of P/M processing is the presence of porosity due to their activity as crack initiators and due to their presence as the stress distribution in compacts is nonhomogeneous in the cross-section. Two atomized iron powders obtained by powder metallurgy with particles of different sizes (< 45, 45-63, 63-100, 100-150, >150 µm) are the based materials studied in this paper. The analyzed powders were subjected to uniaxial pressing with 500 MPa as the applied pressure. The compacts disc dimensions obtained are ϕ 8 × 6 mm in dimensions. The compacts were sintered in a laboratory furnace at a temperature of 1.120 °C. The sintering time was 60 and 90 minutes. The sintered specimens obtained were analyzed regarding their density, microstructure and porosity. Porosity of iron-based P/M materials was measured using the conventional and image processing technique. A correlation between the experimental and software data analysis could be established.

Bearings are machine elements used in a wide variety of applications including transportation. The accurate prediction of a bearing failure is important to sensitive applications to secure its safety during the service life. Bearing failure prediction is useful both in bearing testing phase as well as in case of lifetime use. Real-time Audio signal analysis and advanced algorithms are able to identify the incipient failure, caused by defects, fatigue, overload or poor maintenance. Audio signal analysis and processing remains a domain where technique and algorithm needs to be developed. In this paper is presented a proof-of-concept technique and equipment developed to predict failure of bearings in case of testing phase. For this study, acoustic emission signals were measured and analyzed during life testing of bearing while other sound source are also recorded. Correlation between the acoustic emission patterns were identified in order to identify noise signal and identify the signal associated with bearing degradation. The developed solution to isolate other sounds signals means that the technique could be used while lifetime of the bearings. The results of this study provide evidence that accurate estimation of the failure of various bearings is possible by processing the vibration signal acquired from a single point, even in case of multiple sound sources are present and introduce noise in signal processing. The SVM classifier provides at least 92% mean accuracy. The influence of model on prediction accuracy has also been discussed in the work.

This paper presents the research undertaken by the authors to determine the parameters of electric power produced by a photovoltaic panel using flexible semiconductor polymer cells, aiming a comparative study between this panel and other types of conventional photovoltaic panels, with monocrystalline, polycrystalline and amorphous silicon, based on technical and economic indicators, established under uncertainty conditions. We will also present the variation of these dimensions according to the incidence angle of solar radiation. Thus, researches will show that for its value between 36-38 degrees, you get very good conversion yields. The economic study presented also reveals that under uncertainty there is a correspondence between the panel type and its physical and economic characteristics.

In the topographical surveying works devices have got among the required accessories also tools called tripod. They have the role of correctly installing and settling the equipment above the station point in order to perform the measurements. Various types of tripods are known: the classic tripod (made from aluminum or wood), the adjustable laser tripod, the elevator tripod, the tripod for supporting and adjusting the picket. The aim of this scientific paper is to present my invention that is concerned on a new type of tripod device with photovoltaic cells called mobile solar tripod which has the purpose of providing the energy needed for the equipment used and thus extending the duration of survey measurements by using renewable energies. The tripod being an almost universal accessory along with other topographic instruments, it can be used for some topo-geodetic activities such as monitoring behavior in service stage of buildings, marking the points on the ground, determining ground elevations and other works that require a long time for the objects studied. This present work will describe the advantages and disadvantages of using the existing tripods compared to the new proposed device.

This paper presents the influence of component concentration of a class of polymeric blends with different concentration of PP and PA6 and a constant concentration of additives (CaCO₃, LDPE and an adhesive) Young's modulus does not have a clear tendency of depending on PA6 concentration and testing speeds, but performs in a band between 1500...1900 MPa, except for the value for PA6 at the lowest testing speed (v=10 mm/min), that is 1454.8 MPa. Under large testing speeds, there were cracks or voids towards the loading direction, forming large parallel 'empty channels'. Investigations are done on possible causes of these longitudinal voids in order to clear if they occur during molding or/and during testing and to eliminate them. Except for values at low testing speed, the average values for tensile stress at break perform in a band of less than 8 MPa. The elongation at break is less than 10% for all materials, except for PA6 at the lowest testing speed, when the highest value for this characteristic was obtained. The lowest values were obtained for material with 20% PA6. For blends with 60% and 80% PA6, the difference between values, at the same testing speed, is the smallest. Energy at break has a slightly increase with the concentration of PA6. From the mechanical point of view, among the formulated blends, material D (with 80% PA6) is the most promising as has the highest stress and energy at break (11.43 J at v=10 mm/min and 8.7 J at v=1000 mm/min), but values are still less than those for PA6.

The paper presents the results of the experimental researches as a result of applying the thermo-mechanical treatment for the AlZn4.5Mg1Cu alloy used in the aeronautical industry, in order to optimize the processing parameters. The research is based on a laborious experimental thermomechanical processing program applied to AlZn4.5Mg1Cu aluminium alloy to obtain certain imposed values of the mechanical properties with the lowest possible expense. The objective function in the optimization of the investigated thermomechanical treatment regime is the energy consumption "Q = f (t, τ, ε)" taking into account some restrictions regarding the values of the investigated mechanical properties. The best value for the objective function is obtained by determining values for the independent variables of the thermo mechanical treatment process, for which the conditions for obtaining values imposed on variables dependent on minimum energy consumption Q are met.

The analytic expressions of the mean nearest neighbor distance, the free energy and the thermodynamic quantities for interstitial alloy AB with body-centered cubic (BCC) structure under pressure are derived by the statistical moment method. The theoretical results are applied to interstitial alloy FeH. Our calculated results for Fe as main metal are in good agreement with experiments.

The analytic expressions for free energy, concentration of the equilibrium vacancies and thermodynamic quantities such as the isothermal compressibility, thermal expansion coefficient and heat capacities at constant volume and at constant pressure of FCC interstitial alloy AB with defects under pressure are derived by the statistical moment method. The theoretical results are applied to AuSi interstitial alloy. Our calculated results for main metal Au are compared with the experimental data.

This paper is a review about glass fiber fabrics used for impact protection. The authors comment on types of fabrics, tests done for pointing out the impact resistance. Many of applications refer to ballistic protection but, as one may notice, experimental studies in open literature are disperse from the point of view of parameter ranges. Many articles on the subject do not have details on materials (fabrics and adhesives) used to manufacture the protection samples and on technology for obtaining the final system of protection. Few tests are done according to national, international or military standards because of difficulties in sample manufacturing at industrial scale or the costs related to sample producing. This review could be useful for the start of a research on ballistic panels based on or including glass fiber fabrics, for making the researchers familiar to their particular failure mechanisms.

An alloyed steel grade for machine parts construction used in industry have been considered and this material was subjected to a non-conventional treatment. The samples have been tested using an Amsler stand for dry friction tests and the diffractometric analysis completed this study. The plasma treatment plant used was the INI 150 made by the Institute of Radiation Physics and Technology in collaboration with the "Electrotechnics" Enterprise and the Nuclear Apparatus (I.C.E.FIZ.) from Romania and was destined for technological research. The samples considered for tests were type rollers, with 10 mm width, with different diameters to obtain different sliding degrees {ξ), considering different values for the normal load (Q). This paper is a short review of the researches from last years and realizes a synthesis and a correlation of the results to formulate conclusions on the efficiency of the application of non-conventional treatments in magnetic field on special pieces from industry.

Plasticity is an important property to determine the capability of the steel to support plastic deformations, to obtain important pieces for industry. It is important to know the optimal cooling regime for this material because the steel have been rolling at high temperature or, the steel have been heated at high temperature after lamination process. It was considered a steel grade with a low carbon content, which can be find often in machine industry and in metallurgical operations. Three different mediums for directing of the cooling process have been considered and the properties of the steel have been modified. This study tried to determine a way to improve the properties of this kind of steel to obtain a higher durability corresponding to the exploitation conditions.

The purpose of this paper is to find a damping material for the vibrations generated by the equipment of a ship. That will improve the working and resting conditions of seafaring personnel on a pusher boat that travels over long distances. The experiments were made upstream the Danube. The convoy was made up of a self-propelled vessel and four barges. The water flow rate was 0.76 m/s and there were good visibility conditions and light wind. The accelerations transmitted to man were measured with Seat PAD 01dB triaxial accelerometers mounted on the floor of the ship and connected to the NetdB-Complex system for analysis and measurement. The working frequencies were 0÷100 Hz. Subjects were placed directly on the ship's deck, then on neoprene and rigid foam. It was found that for longitudinal vibrations, the r.m.s. accelerations are 9 times higher than standard if there is no attenuator, 4.8 times higher than standard for neoprene and 2.4 times higher in the case of rigid foam. For transverse vibrations, r.m.s. accelerations are 10.8 times higher than standard when there is no attenuator, 6.4 times higher in the neoprene case and 2.7 times higher for rigid foam. For vertical vibrations, accelerations r.m.s is 5.9 times higher than standard if there is no attenuator, 3.4 times higher for neoprene and 1.7 times higher for rigid foam. The results are similar in the case of transmissibility determination. It was shown the importance of a vibration attenuator for the health, comfort and implicitly for labour productivity of river sailing personnel.

The present paper analyses the effects of five different heat treatment temperatures, between 973, 1073, ... and 1373 K as well as two mechanical alloying (MA) fractions, 0 and 40 vol. %, on the evolution of damping behavior of an Fe-Mn-Si-Cr-Ni Shape Memory Alloy (SMA) obtained by powder metallurgy (PM). From the 10 types of samples, rectangular specimens were cut by wire-spark erosion for dynamic mechanical analysis (DMA) tests. DMA tests were performed by temperature scans (TS) and strain sweeps (SS). TS were applied between room temperature (RT) and 673 K, at constant amplitude, and thus enabled determining the temperatures of internal friction maxima associated with antiferromagnetic-paramagnetic transition (Néel temperature), ${A}_{50}^{N}$, and ε-martensite reversion to γ-austenite, ${A}_{50}^{\varepsilon }$, as a function of MA'ed fraction and HT temperature. SS were applied during three cycles with increasing strain amplitude and performed at three temperatures: (i) T₁=RT; (ii) ${{\rm{T}}}_{2}\lt {A}_{50}^{\varepsilon }$ and (iii) ${{\rm{T}}}_{3}\gt {A}_{50}^{\varepsilon }$. The effects of HT temperature and MA'ed fraction on storage modulus (E') values were emphasized for each of the three temperatures T_1,2,3. An E'-plateau was observed and associated with the formation of ε stress induced martensite, during DMA-SS.

In this paper is presented the structural analysis carried out on samples from a compressed air cylinder subjected to explosion. The air cylinder was mounted on public transport bus. The risk that the incident would repeat with other similar cylinders carrying compressed air required a detailed study regarding the causes that led to the catastrophic degradation. The research by micro and macro structural analysis has highlighted several factors that have increased the damage. The optical micrographs are obtained using an Olympus metallographic microscope equipped with a digital camera, with the possibility to automatically assign the microstructure magnification and with automatic software for linear measurements. The research regarding the appearance of the inner surface of the compressed air cylinder container has highlighted an accentuated corrosion process, developed in the thickness of the cylinder wall with a non-uniform thickness. The break occurred near the welding, known as thermal influence zone (the analyzed cylinder being welded longitudinally). The research has shown that inter-crystalline corrosion associated with pitting (punctiform) corrosion developed between the dendrite branches leads to an intense metal degradation in the wall depth and, in limited cases, causes perforation of the metal wall, increasing the explosive fracture development. A factor that influenced the corrosion process in the ZIT area was the mounting of the compressed air cylinder with the welded area at the bottom of the component.

In this paper, the authors chose to study the non-alloy steel grade S235JR, developed in the LD (Lintz-Donawitz) converter from Arcelor Mittal Galati plant, considering the quality and purity improving of the produced steel as a main objective. The correlation of mechanical properties with steel purity, as a result of the liquid steel processing to the continuous casting machine (CC) using three cases was followed. In the first case, the final chemical analysis of the liquid steel was taken at the end of the blowing operation without desulphurisation and degassing. In the 2nd case, the final chemical analysis of the liquid steel for CC was taken after the desulphurisation and chemical and thermal homogenization in the Ladle Furnace (LF) installation. In the 3rd case, the final chemical analysis of the liquid steel for CC was taken after the vacuum degassing, i.e after the treatment in the Ruhrstahl Heraeus (RH) installation.

Two series of Mn substituted Fe-Pd ferromagnetic shape memory ribbons were studied by X-ray diffraction, calorimetric and thermo-induced strain measurements. Linking the structural, magnetic and thermal expansion analysis on pristine ribbons and those subjected to different subsequent thermal treatments, highlights the role of substitution and of heat treatment of the martensitic transformation (MT). The melt–spinning technique removes the precipitation of undesirable b.c.t. irreversible phase and the addition of Mn, as a third alloying element, promotes the stabilization of the f.c.t. martensite. The linear thermal expansion measurements with and without static magnetic field provide information on the easy magnetization axis in the martensitic structure. Preliminary in vitro cytotoxicity tests generally indicate no toxicity or a tendency towards cell proliferation induced by the tested materials.

Graphene is a two-dimensional wonder material, used for electronic and medical applications. To date, various synthesis method of graphene layers is proposed, such as: SiC epitaxial growth, Chemical Vapor Deposition (CVD) and mechanical exfoliation. Graphene single layer can be rapidly produced by CVD. Although the transfer process on different substrates has been researched, a post-processing step after graphene growth for understanding influence of radical of carbon unreacted in graphene properties has not been studied. Deposition of graphene on metal transition substrate involves many reactions, and is not clear what happens with the unreacted methane. The scanning electron microscopy is the best method to visualize this unreacted species as a thin film which covers the graphene layer. The post-processing of graphene after CVD is a crucial step for the performance of graphene-based devices. The graphene film is characterized morphologically and structurally before and after the post-processing step, with the scope of removing the unreacted film and investigating the influence of this step on the graphene properties. To identify the specific vibration of graphene layer before and after post-processing step, Raman spectroscopy has been used. Here, we investigate the quality of CVD graphene before and after removing unreacted hydrocarbon, to better understand the importance of post-processing process for device applications, before the graphene transfer.

Acquiring new permanent magnets without Rare-Earths is a new challenge in the field of magnetic materials and Co-rich Co-Zr alloys seem to be a solution to be pursued. The microalloying effects of different elements on the structure and stabilization of hard magnetic Zr₂Co₁₁ phase of Zr-Co alloy have been analysed in the past and it was shown that the Zr₂Co₁₁ non-cubic high anisotropy structure can be stabilized by the partial substitution of Co in the ZrCo alloy with elements with high atomic radius. In the present work, we made substitutions of up to 5% alloying elements such as Mo, C, B, Cr in order to highlight how the element with the small / large atomic radius stabilize the nano-hard magnetic phase. The structural and magnetic properties of the new Zr₁₈Co₇₇Cr₃X₂ (X = C, B, Mo) prepared bulk alloys have been analysed and related to those of the original Zr₁₃Co₈₇.