monica Lohan - Academia.edu (original) (raw)
Papers by monica Lohan
367-375Specimens with truncated cone shell shapes (modules) are processed by high-speed high pres... more 367-375Specimens with truncated cone shell shapes (modules) are processed by high-speed high pressure torsion (HS-HPT), from circular crowns cut from shape memory alloy (SMA) ingots with nominal chemical composition Fe-28Mn-6Si-5Cr (mass%). Mechanical tests are performed comprising hardness measurements and loading-unloading compression cycles applied between dry or lubricated flat surfaces. A hardness gradient of 22 HV/mm is obtained along truncated cone generator, increasing from inner to outer areas, due to different deformation degrees, in these zones. Each loading and unloading stage was accompanied by steady and reproducible force plateaus, attributed to gradual elastic flattening of the modules, due to hardness gradient, suggesting a “superelastic-like” behaviour which is never reported in Fe-Mn-Si based SMAs. During cycling, the modules experienced a training effect consisting in the increase of relative shape recovery degree, up to 97%, with the number of cycles. Trained modules displayed multifunctional character, being able to develop constrained recovery forces when heated in compressed state, above a certain critical temperature. Constrained recovery forces are higher than those reached during isothermal compression. The modules are characterized, in different training stages, by optical and scanning electron microscopy, as well as by X-ray diffraction (XRD). As an effect of HS-HPT processing the formation of highly distorted martensite plate variants is revealed on the XRD patterns, which also emphasized the stress-induced formation of crystalline reoriented ε hexagonal close-packed martensite after compression cycles
SSRN Electronic Journal, 2015
Organizational Citizenship behavior (OCB) is a type of behavior which is also known as the Extra ... more Organizational Citizenship behavior (OCB) is a type of behavior which is also known as the Extra Role Behavior, Motivate the employees to go beyond what is expected from them by organization and job descriptions, this type of behavior have its benefits for both production parts employees and organizations.In Egypt and especially in Cement industry the term (OCB) still new concept and till now the companies didn’t realize the importance of having this type of behavior among its employees.Several researcher have found that there is a significant positive relationship between employee job satisfaction and Organizational Citizenship Behavior, which affect the employee and the organization performance.This research aim to investigate the relationship between job satisfaction(Intrinsic and Extrinsic) as independent variable and Organizational Citizenship Behavior as dependent variable among Beni Suef Cement Company employees, this study will provide guidelines to help the senior management of the company to measure and understand how Job satisfaction affect organizational citizenship behavior of their team members.
Materials Today: Proceedings
Materials Today: Proceedings
Frontiers in Materials Processing, Applications, Research and Technology, 2017
Journal of Testing and Evaluation, 2016
By means of atomic force microscopy (AFM) measurements, the evolution of surface relief character... more By means of atomic force microscopy (AFM) measurements, the evolution of surface relief characteristics of stress induced martensite plates was investigated on the surface of polished Fe-14Mn-6Si-9Cr-5Ni and Fe–28Mn–6Si–5Cr (mass. %) shape memory alloys (SMAs), subjected to various pre-straining degrees. Pre-straining degree was chosen as an independent variable, considering its influence on the reverse transformation of martensite. The specimens were cast by means of a levitation induction furnace and hot rolled to 1 mm-thickness in order to better reveal the shape memory phenomena. The specimens, cut by spark erosion to “dog-bone” shapes, were pre-strained by means of a tensile testing machine at room temperature (RT). The gauges of elongated specimens were analyzed by AFM. Qualitative 2D analyses were performed on AFM micrographs. Quantitative evaluations were based on systematic dimensional measurements of martensite profiles, allowing the determination of the average values of plate widths and heights for four pre-straining degrees of the two SMA systems under study. The variation tendencies of average values of martensite plate widths and heights with increasing the pre-straining were examined under the form of increasing rates of the plate widths and heights. The results show that, for the two SMA systems studied, the average widths and heights of stress-induced martensite plates varied between 80 and 188 nm for Fe-14Mn-6Si-9Cr-5Ni and between 101 and 192 nm for Fe-28Mn-6Si-5Cr. These dimensions experienced an increasing tendency with pre-straining degree, with a rate of about 30 nm/ % pre-strain.
Materials Science Forum, 2017
Cu-Zn-Al shape memory alloys (SMAs) were analysed in two different processing states: (i) hot-for... more Cu-Zn-Al shape memory alloys (SMAs) were analysed in two different processing states: (i) hot-forged and (ii) hot-rolled. Both hot-forged and hot-rolled specimens were cut into lamellar configuration, before being homogenized (1073 K/ 18 ks/ water) and tempered (373, 473, 573, 673 K/ 300 s/ water). From each of the five differently treated lamellas, in hot-forged and hot-rolled states, rectangular specimens were cut for dynamic mechanical analysis (DMA). The remaining segments were sectioned into metallographic specimens. The metallographic specimens were embedded into could mounting resin, ground, polished and etched for scanning electron microscopy (SEM) -observations. DMA results revealed the influence of plastic deformation procedure and heat treatment temperature on the reversible martensitic transformation.
Materials Science Forum, 2017
The paper introduces the possibility to replace the “wet alloy”, used for sprinkler-triggering wi... more The paper introduces the possibility to replace the “wet alloy”, used for sprinkler-triggering within automatic fire protection systems, with a shape memory alloy (SMA) type. The idea of the present application is based on the thermoelastic reversible martensitic transformation, governing SMA functioning, which has completely reversible character, and enables the occurrence of two-way shape memory effect (TWSME) after the application of a thermomechanical treatment called “training”. For this purpose a commercial NiTi rod, which was martensitic at room temperature, was subjected to thermal analysis tests, performed by differential scanning calorimetry (DSC) and dilatometry. Martensite (M) reversion to parent phase (A), during heating, was emphasized by an endothermic peak on the DSC thermogram and by a length shrinkage, on the dilatogram. The capacity to develop TWSME was revealed by the change in displacement-temperature variation, with increasing the number of training cycles. Thi...
7th Forum on New Materials - Part A, 2016
Fe-14Mn-6Si-9Cr-5Ni (wt. %) shape memory alloys (SMAs) were produced by powder metallurgy (PM) co... more Fe-14Mn-6Si-9Cr-5Ni (wt. %) shape memory alloys (SMAs) were produced by powder metallurgy (PM) combined with Mechanical Alloying (MA). The specimens were pressed and sintered under Ar atmosphere from as blended powders as well as from mixtures of as blended and 10, 20, 30 and 40 vol. % MA’ed powders, respectively. The five groups of sintered specimens were hot-rolled, spark-erosion cut and solution treated at five temperatures (923, 1023, …, 1373K/ 300 s/ water). Tensile loading-unloading tests were performed in order to obtain stress-induced martensite at different pre-straining degrees. The static responses of the twenty five types of specimens were evaluated by means of the surface areas under unloading curve (E2) and between loading and unloading curves (E1) which were used for determining static internal friction, Q-1. The dynamic responses of the undeformed specimens were determined by Dynamic Mechanical Analysis (DMA) performed at room temperature with a three-point-bending s...
MATEC Web of Conferences, 2015
Materials Today: Proceedings, 2015
Journal of Testing and Evaluation, 2015
The effects of thermal cycling in an experimental hydraulic installation of trained shape memory ... more The effects of thermal cycling in an experimental hydraulic installation of trained shape memory alloy actuators are discussed. After being trained in air for up to 500 flection–deflection cycles during cooling–heating, respectively, with a load fastened at their free ends, the lamellar elements developed two way shape memory effect by reducing their curvature during heating and by recovering it during cooling. Temperature variations versus time were recorded during thermal cycling performed in oil, revealing the influences of: (i) the number of training cycles, (ii) overheating caused by oil thermal-inertia, and (iii) heating interruption during martensite reversion to parent phase. The effects of the number of training cycles, corroborated with heating interruption, were revealed by differential scanning calorimetry both before and after functioning in oil. Heating interruption, associated with temperature memory effect, caused the occurrence of two martensite populations during subsequent cooling, as substantiated by optical and atomic force microscopy.
Materials Science Forum, 2013
Fe-14 Mn-6 Si-9 Cr-5 Ni (mass. %) shape memory alloys (SMAs) were produced from raw powders emplo... more Fe-14 Mn-6 Si-9 Cr-5 Ni (mass. %) shape memory alloys (SMAs) were produced from raw powders employed both in initial commercial state and in a mixture state of equal fractions of commercial and mechanically alloyed (MA’d) particles. After blending, pressing and sintering, powder compacts were hot rolled (HR’d) and solution treated (ST’d) before being machined into plane-parallel lamellas. Specimens with special geometry were pre-strained on a tensile testing machine. By means of X-ray diffraction (XRD) and scanning electron microscopy (SEM) the presence of ε hexagonal close packed and α’ body center cubic stress induced martensites was revealed and their thermally induced reversion to γ face center cubic austenite was evaluated by modulated differential scanning calorimetry (MDSC). The results enabled the study of the influence of MA, HR, ST and pre-straining on phase structure and associated on shape memory effect (SME). The lamellas were hot formed into rings, which were trained i...
International Journal of Materials Research, 2011
Different fragments of martensitic Cu-14.86 Zn-5.81 Al-0.5 Fe (mass.%) shape memory alloy were su... more Different fragments of martensitic Cu-14.86 Zn-5.81 Al-0.5 Fe (mass.%) shape memory alloy were subjected to heating, up to 453 K, with different rates ranging from 1.66 ×10−2 K s−1 to 54.6 × 1.66 × 10−2 K s−1, performed by means of a differential scanning calorimeter. In all cases, during heating, an endothermic peak was observed which was associated with the martensite reversion to parent phase. By means of the differential scanning calorimeter charts the critical transformation temperatures of martensite reversion were determined using the tangent method. The effects of heating rate were evaluated from the point of view: (i) of variation tendencies of critical transformation temperatures; (ii) of deviations of experimental values from linear fit and extrapolation to zero heating rate; and (iii) of corroborating morphological changes of martensite (sub)plates with heat flow variation particularities. The results prove that there is an obvious tendency of critical transformation tem...
IOP Conference Series: Materials Science and Engineering, 2019
Fe43.5Mn34Al15Ni7.5 shape memory alloys (SMAs), have drawn considerable attention from the part o... more Fe43.5Mn34Al15Ni7.5 shape memory alloys (SMAs), have drawn considerable attention from the part of scientific community due to its superelastic behaviour, stable over a large thermal range (from -50 to +150°C) [1]. After cyclic heat treatment, solution treatment and ageing, the specimens became oligocrystalline and were reinforced by NiAl nanoprecipitates. The typical thermomechanical processing routine, before cyclic heat treatment of FeMnAlNi alloys, involves hot rolling, annealing and cold rolling [2]. The present paper discusses the effects of ± 1.5 at. % aluminium substitution with nickel, by correlating tensile behaviour with microstructural observations. The SMA specimens with chemical composition Fe43.5Mn34Al15±1.5Ni7.5∓1.5 were subjected to tensile tests, comprising loading-unloading cycles, based on which recoverable strain and energy storage efficiency were calculated. Considering that, in each cycle, a permanent strain was obtained, it follows that not all of the amount ...
Polymers
Due to the pressing problems of today’s world, regarding both the finding of new, environmentally... more Due to the pressing problems of today’s world, regarding both the finding of new, environmentally friendly materials which have the potential to replace classic ones, and the need to limit the accelerated spread of bacteria in hospitals, offices and other types of spaces, many researchers have chosen to develop their work in this field. Thus, biopolymeric materials have evolved so much that they are gradually becoming able to remove fossil-based plastics from major industries, which are harmful to the environment and implicitly to human health. The biopolymer employed in the present study, Arboblend V2 Nature with silver nanoparticle content (AgNP) meets both aspects mentioned above. The main purpose of the paper is to replace several parts and products in operation which exhibit antibacterial action, preventing the colonization and proliferation of bacteria (Streptococcus pyogenes and Staphylococcus aureus, by using the submerged cultivation method), but also the possibility of deg...
The Annals of "Dunarea de Jos" University of Galati. Fascicle IX, Metallurgy and Materials Science, 2014
The present work reports the evolution of micro-structure and shape memory behavior in a Cu-15 Zn... more The present work reports the evolution of micro-structure and shape memory behavior in a Cu-15 Zn-6 Al (mass. %) shape memory alloy (SMA), as a function of the applied hot working procedure and of the performed heat treatments. To this purpose a special compressed-air forging hammer was employed. The samples were heated up to 1023 K into an electric furnace and swaged on a compressed-air forging hammer, by multiple blows. After several blows, the specimens were prepared, by maintaining the main plastic deformation direction, for structural analysis, being cut, embedded, ground, polished and etched. Structural analysis comprised optical (OM) and scanning electron (SEM) microscopy observations, performed with the view of emphasizing the morphological aspects of martensite and bainite. To reveal the atomic fluctuations, enabled by hot forging, energy dispersive X-ray spectroscopy analysis (EDS) measurements were performed by means of SEM analysis. The paper reports the results of OM, S...
IOP Conference Series: Materials Science and Engineering, 2017
MATEC Web of Conferences, 2015
Materials Today: Proceedings, 2015
Abstract The evolution of surface relief characteristics of stress induced martensite plates was ... more Abstract The evolution of surface relief characteristics of stress induced martensite plates was investigated at Fe-Mn-Si-Cr, Fe-Mn-Si-Cr-Ni and Cu-Al-Ni shape memory alloys (SMAs), subjected to tensile deformation. Hot-rolled specimens underwent different successive stages of pre-straining, by means of a tensile testing machine, at room temperature (RT). The gauges of polished elongated specimens were analyzed by optical and atomic force microscopy. Quantitative evaluations were based on systematic dimensional measurements of the widths and heights of different martensite plate profiles. The results were used to statistically evaluate the variation tendencies, with pre-strain degree increasing, of the width and height of martensite plates.
367-375Specimens with truncated cone shell shapes (modules) are processed by high-speed high pres... more 367-375Specimens with truncated cone shell shapes (modules) are processed by high-speed high pressure torsion (HS-HPT), from circular crowns cut from shape memory alloy (SMA) ingots with nominal chemical composition Fe-28Mn-6Si-5Cr (mass%). Mechanical tests are performed comprising hardness measurements and loading-unloading compression cycles applied between dry or lubricated flat surfaces. A hardness gradient of 22 HV/mm is obtained along truncated cone generator, increasing from inner to outer areas, due to different deformation degrees, in these zones. Each loading and unloading stage was accompanied by steady and reproducible force plateaus, attributed to gradual elastic flattening of the modules, due to hardness gradient, suggesting a “superelastic-like” behaviour which is never reported in Fe-Mn-Si based SMAs. During cycling, the modules experienced a training effect consisting in the increase of relative shape recovery degree, up to 97%, with the number of cycles. Trained modules displayed multifunctional character, being able to develop constrained recovery forces when heated in compressed state, above a certain critical temperature. Constrained recovery forces are higher than those reached during isothermal compression. The modules are characterized, in different training stages, by optical and scanning electron microscopy, as well as by X-ray diffraction (XRD). As an effect of HS-HPT processing the formation of highly distorted martensite plate variants is revealed on the XRD patterns, which also emphasized the stress-induced formation of crystalline reoriented ε hexagonal close-packed martensite after compression cycles
SSRN Electronic Journal, 2015
Organizational Citizenship behavior (OCB) is a type of behavior which is also known as the Extra ... more Organizational Citizenship behavior (OCB) is a type of behavior which is also known as the Extra Role Behavior, Motivate the employees to go beyond what is expected from them by organization and job descriptions, this type of behavior have its benefits for both production parts employees and organizations.In Egypt and especially in Cement industry the term (OCB) still new concept and till now the companies didn’t realize the importance of having this type of behavior among its employees.Several researcher have found that there is a significant positive relationship between employee job satisfaction and Organizational Citizenship Behavior, which affect the employee and the organization performance.This research aim to investigate the relationship between job satisfaction(Intrinsic and Extrinsic) as independent variable and Organizational Citizenship Behavior as dependent variable among Beni Suef Cement Company employees, this study will provide guidelines to help the senior management of the company to measure and understand how Job satisfaction affect organizational citizenship behavior of their team members.
Materials Today: Proceedings
Materials Today: Proceedings
Frontiers in Materials Processing, Applications, Research and Technology, 2017
Journal of Testing and Evaluation, 2016
By means of atomic force microscopy (AFM) measurements, the evolution of surface relief character... more By means of atomic force microscopy (AFM) measurements, the evolution of surface relief characteristics of stress induced martensite plates was investigated on the surface of polished Fe-14Mn-6Si-9Cr-5Ni and Fe–28Mn–6Si–5Cr (mass. %) shape memory alloys (SMAs), subjected to various pre-straining degrees. Pre-straining degree was chosen as an independent variable, considering its influence on the reverse transformation of martensite. The specimens were cast by means of a levitation induction furnace and hot rolled to 1 mm-thickness in order to better reveal the shape memory phenomena. The specimens, cut by spark erosion to “dog-bone” shapes, were pre-strained by means of a tensile testing machine at room temperature (RT). The gauges of elongated specimens were analyzed by AFM. Qualitative 2D analyses were performed on AFM micrographs. Quantitative evaluations were based on systematic dimensional measurements of martensite profiles, allowing the determination of the average values of plate widths and heights for four pre-straining degrees of the two SMA systems under study. The variation tendencies of average values of martensite plate widths and heights with increasing the pre-straining were examined under the form of increasing rates of the plate widths and heights. The results show that, for the two SMA systems studied, the average widths and heights of stress-induced martensite plates varied between 80 and 188 nm for Fe-14Mn-6Si-9Cr-5Ni and between 101 and 192 nm for Fe-28Mn-6Si-5Cr. These dimensions experienced an increasing tendency with pre-straining degree, with a rate of about 30 nm/ % pre-strain.
Materials Science Forum, 2017
Cu-Zn-Al shape memory alloys (SMAs) were analysed in two different processing states: (i) hot-for... more Cu-Zn-Al shape memory alloys (SMAs) were analysed in two different processing states: (i) hot-forged and (ii) hot-rolled. Both hot-forged and hot-rolled specimens were cut into lamellar configuration, before being homogenized (1073 K/ 18 ks/ water) and tempered (373, 473, 573, 673 K/ 300 s/ water). From each of the five differently treated lamellas, in hot-forged and hot-rolled states, rectangular specimens were cut for dynamic mechanical analysis (DMA). The remaining segments were sectioned into metallographic specimens. The metallographic specimens were embedded into could mounting resin, ground, polished and etched for scanning electron microscopy (SEM) -observations. DMA results revealed the influence of plastic deformation procedure and heat treatment temperature on the reversible martensitic transformation.
Materials Science Forum, 2017
The paper introduces the possibility to replace the “wet alloy”, used for sprinkler-triggering wi... more The paper introduces the possibility to replace the “wet alloy”, used for sprinkler-triggering within automatic fire protection systems, with a shape memory alloy (SMA) type. The idea of the present application is based on the thermoelastic reversible martensitic transformation, governing SMA functioning, which has completely reversible character, and enables the occurrence of two-way shape memory effect (TWSME) after the application of a thermomechanical treatment called “training”. For this purpose a commercial NiTi rod, which was martensitic at room temperature, was subjected to thermal analysis tests, performed by differential scanning calorimetry (DSC) and dilatometry. Martensite (M) reversion to parent phase (A), during heating, was emphasized by an endothermic peak on the DSC thermogram and by a length shrinkage, on the dilatogram. The capacity to develop TWSME was revealed by the change in displacement-temperature variation, with increasing the number of training cycles. Thi...
7th Forum on New Materials - Part A, 2016
Fe-14Mn-6Si-9Cr-5Ni (wt. %) shape memory alloys (SMAs) were produced by powder metallurgy (PM) co... more Fe-14Mn-6Si-9Cr-5Ni (wt. %) shape memory alloys (SMAs) were produced by powder metallurgy (PM) combined with Mechanical Alloying (MA). The specimens were pressed and sintered under Ar atmosphere from as blended powders as well as from mixtures of as blended and 10, 20, 30 and 40 vol. % MA’ed powders, respectively. The five groups of sintered specimens were hot-rolled, spark-erosion cut and solution treated at five temperatures (923, 1023, …, 1373K/ 300 s/ water). Tensile loading-unloading tests were performed in order to obtain stress-induced martensite at different pre-straining degrees. The static responses of the twenty five types of specimens were evaluated by means of the surface areas under unloading curve (E2) and between loading and unloading curves (E1) which were used for determining static internal friction, Q-1. The dynamic responses of the undeformed specimens were determined by Dynamic Mechanical Analysis (DMA) performed at room temperature with a three-point-bending s...
MATEC Web of Conferences, 2015
Materials Today: Proceedings, 2015
Journal of Testing and Evaluation, 2015
The effects of thermal cycling in an experimental hydraulic installation of trained shape memory ... more The effects of thermal cycling in an experimental hydraulic installation of trained shape memory alloy actuators are discussed. After being trained in air for up to 500 flection–deflection cycles during cooling–heating, respectively, with a load fastened at their free ends, the lamellar elements developed two way shape memory effect by reducing their curvature during heating and by recovering it during cooling. Temperature variations versus time were recorded during thermal cycling performed in oil, revealing the influences of: (i) the number of training cycles, (ii) overheating caused by oil thermal-inertia, and (iii) heating interruption during martensite reversion to parent phase. The effects of the number of training cycles, corroborated with heating interruption, were revealed by differential scanning calorimetry both before and after functioning in oil. Heating interruption, associated with temperature memory effect, caused the occurrence of two martensite populations during subsequent cooling, as substantiated by optical and atomic force microscopy.
Materials Science Forum, 2013
Fe-14 Mn-6 Si-9 Cr-5 Ni (mass. %) shape memory alloys (SMAs) were produced from raw powders emplo... more Fe-14 Mn-6 Si-9 Cr-5 Ni (mass. %) shape memory alloys (SMAs) were produced from raw powders employed both in initial commercial state and in a mixture state of equal fractions of commercial and mechanically alloyed (MA’d) particles. After blending, pressing and sintering, powder compacts were hot rolled (HR’d) and solution treated (ST’d) before being machined into plane-parallel lamellas. Specimens with special geometry were pre-strained on a tensile testing machine. By means of X-ray diffraction (XRD) and scanning electron microscopy (SEM) the presence of ε hexagonal close packed and α’ body center cubic stress induced martensites was revealed and their thermally induced reversion to γ face center cubic austenite was evaluated by modulated differential scanning calorimetry (MDSC). The results enabled the study of the influence of MA, HR, ST and pre-straining on phase structure and associated on shape memory effect (SME). The lamellas were hot formed into rings, which were trained i...
International Journal of Materials Research, 2011
Different fragments of martensitic Cu-14.86 Zn-5.81 Al-0.5 Fe (mass.%) shape memory alloy were su... more Different fragments of martensitic Cu-14.86 Zn-5.81 Al-0.5 Fe (mass.%) shape memory alloy were subjected to heating, up to 453 K, with different rates ranging from 1.66 ×10−2 K s−1 to 54.6 × 1.66 × 10−2 K s−1, performed by means of a differential scanning calorimeter. In all cases, during heating, an endothermic peak was observed which was associated with the martensite reversion to parent phase. By means of the differential scanning calorimeter charts the critical transformation temperatures of martensite reversion were determined using the tangent method. The effects of heating rate were evaluated from the point of view: (i) of variation tendencies of critical transformation temperatures; (ii) of deviations of experimental values from linear fit and extrapolation to zero heating rate; and (iii) of corroborating morphological changes of martensite (sub)plates with heat flow variation particularities. The results prove that there is an obvious tendency of critical transformation tem...
IOP Conference Series: Materials Science and Engineering, 2019
Fe43.5Mn34Al15Ni7.5 shape memory alloys (SMAs), have drawn considerable attention from the part o... more Fe43.5Mn34Al15Ni7.5 shape memory alloys (SMAs), have drawn considerable attention from the part of scientific community due to its superelastic behaviour, stable over a large thermal range (from -50 to +150°C) [1]. After cyclic heat treatment, solution treatment and ageing, the specimens became oligocrystalline and were reinforced by NiAl nanoprecipitates. The typical thermomechanical processing routine, before cyclic heat treatment of FeMnAlNi alloys, involves hot rolling, annealing and cold rolling [2]. The present paper discusses the effects of ± 1.5 at. % aluminium substitution with nickel, by correlating tensile behaviour with microstructural observations. The SMA specimens with chemical composition Fe43.5Mn34Al15±1.5Ni7.5∓1.5 were subjected to tensile tests, comprising loading-unloading cycles, based on which recoverable strain and energy storage efficiency were calculated. Considering that, in each cycle, a permanent strain was obtained, it follows that not all of the amount ...
Polymers
Due to the pressing problems of today’s world, regarding both the finding of new, environmentally... more Due to the pressing problems of today’s world, regarding both the finding of new, environmentally friendly materials which have the potential to replace classic ones, and the need to limit the accelerated spread of bacteria in hospitals, offices and other types of spaces, many researchers have chosen to develop their work in this field. Thus, biopolymeric materials have evolved so much that they are gradually becoming able to remove fossil-based plastics from major industries, which are harmful to the environment and implicitly to human health. The biopolymer employed in the present study, Arboblend V2 Nature with silver nanoparticle content (AgNP) meets both aspects mentioned above. The main purpose of the paper is to replace several parts and products in operation which exhibit antibacterial action, preventing the colonization and proliferation of bacteria (Streptococcus pyogenes and Staphylococcus aureus, by using the submerged cultivation method), but also the possibility of deg...
The Annals of "Dunarea de Jos" University of Galati. Fascicle IX, Metallurgy and Materials Science, 2014
The present work reports the evolution of micro-structure and shape memory behavior in a Cu-15 Zn... more The present work reports the evolution of micro-structure and shape memory behavior in a Cu-15 Zn-6 Al (mass. %) shape memory alloy (SMA), as a function of the applied hot working procedure and of the performed heat treatments. To this purpose a special compressed-air forging hammer was employed. The samples were heated up to 1023 K into an electric furnace and swaged on a compressed-air forging hammer, by multiple blows. After several blows, the specimens were prepared, by maintaining the main plastic deformation direction, for structural analysis, being cut, embedded, ground, polished and etched. Structural analysis comprised optical (OM) and scanning electron (SEM) microscopy observations, performed with the view of emphasizing the morphological aspects of martensite and bainite. To reveal the atomic fluctuations, enabled by hot forging, energy dispersive X-ray spectroscopy analysis (EDS) measurements were performed by means of SEM analysis. The paper reports the results of OM, S...
IOP Conference Series: Materials Science and Engineering, 2017
MATEC Web of Conferences, 2015
Materials Today: Proceedings, 2015
Abstract The evolution of surface relief characteristics of stress induced martensite plates was ... more Abstract The evolution of surface relief characteristics of stress induced martensite plates was investigated at Fe-Mn-Si-Cr, Fe-Mn-Si-Cr-Ni and Cu-Al-Ni shape memory alloys (SMAs), subjected to tensile deformation. Hot-rolled specimens underwent different successive stages of pre-straining, by means of a tensile testing machine, at room temperature (RT). The gauges of polished elongated specimens were analyzed by optical and atomic force microscopy. Quantitative evaluations were based on systematic dimensional measurements of the widths and heights of different martensite plate profiles. The results were used to statistically evaluate the variation tendencies, with pre-strain degree increasing, of the width and height of martensite plates.