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Sorin Savu

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Yuriy L Raikher

Perm National Research Polytechnic University

Joint Institute for Nuclear Research

Олександр Томчук

Мазахир Н А С Р Е Д Д И Н Байрамов

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Papers by Sorin Savu

Microstructure of magnetite doped elastomers investigated by SAXS and SANS

We present some recent results on the SAXS and SANS investigations of the magnetic elastomers. Sa... more We present some recent results on the SAXS and SANS investigations of the magnetic elastomers. Samples were obtained by polymerizing dimethylsiloxane with Fe 3 O 4 ferrofluid in a magnetic field and without magnetic field and characterized by XRD, SANS and SAXS. The SAXS maximum at large angles, obtained from magnetic elastomers, was fitted by using a Pseudo-Voigt function. It was found that the Fe 3 O 4 particles lead to a significant change of the local structure of elastomer, meaning the decrease of the quasi-crystalline phase and the micro-strains into the matrix. The average particle size obtained from SANS measurements agrees well with the average particle size determined by XRD and SAXS analysis. The splitting of the SANS intensity owing to an additional scattering in zero field reflects the existence of magnetic correlations inside the Q region of 0.005 Å -1 < Q < 0.02 Å -1 .

Hybrid heating in Fused Filament Fabrication process

Research Square (Research Square), Apr 4, 2024

Changing the heating regime of the polymer during printing by the Fused Filament Fabrication (FFF... more Changing the heating regime of the polymer during printing by the Fused Filament Fabrication (FFF) process can produce changes in the behavior of the polymer, but also changes in the characteristics of the printed product. The work proposes to replace the traditional resistive heating system with two hybrid heating systems that bring an additional temperature of 120-160 o C: resistive and hot air jet, resistive and infrared radiation. The samples printed by using the two hybrid heating systems were DSC analyzed and visual tested. The filaments used for the experimental program were commercial filaments of ABS and PLA. A model to evaluate the melting of the polymer during the printing process was proposed, and it was experimentally confirmed. The visual testing revealed that the printed lattice's structure is characterized by lower dimension voids of the structure, being built by depositions that are not circular in section, but flattened, due to the longer time in viscous / partially molten state. The elongation viscosity and the storage modulus decreased with about 10%, being slightly lower in the case of the infrared radiation heat source. The glassy temperature remained unchanged; the mobility of the molecules being not affected by the supplementary heat. The energy consumed to form the crystals is not changed by the supplementary heat. Mechanical behavior of the printed piece, during compression tests, was also influenced by the addition of the second heat source. For both materials a decrease in deformability is recorded as the temperature of the hot air jet increases. Highlights 1. Hybrid source for heating in FFF printing 2. Influence of hybrid heating on the characteristics of the deposited material 3. Thermal field in the deposited material 4. Modelling of thermal field 5. Changing in DSC thermograms for PLA and for ABS due to hybrid heating Keywords hybrid heating; DSC analysis; lattices structure; thermal field; thermal and mechanical characteristics

Creation of New Generation Titanium Diboride Composite Armour Material

NATO science for peace and security series, 2020

The next generation Armour Piercing Bullet with Tungsten Carbide core has been introduced into th... more The next generation Armour Piercing Bullet with Tungsten Carbide core has been introduced into the world's leading military forces by the beginning of the twenty-first century, and later, into the Russian army, which has resulted in a sharp increase in penetrability of the existing standard composite armour plates. The only armour system that effectively stops these bullets is a combined structure obtained through a hot-pressing technology and composed of multilayer fabric made of highmolecular organic fibres. Despite the high armour properties of the above-mentioned structure, its components (separately and together) have some negative sides as well: high cost, low production capacity and low firmness of armour ceramics, which hinders its widespread use in personal protective equipment and in armoured combat vehicles as well. Therefore, there was a need to find new approaches in processing technologies of protective structure and its new components in order to create a new generation armour material for ceramic armour characterized by high hardness and strength (not less than boron carbide), low cost and high capacity and with the following physical-mechanical properties: micro hardness-3600-3800 kg/mm 2 ; bending strength 70-80 kg/mm 2 ; density-4.0-4.5 g/cm 3. The obtained results will allow us to replace the boron carbide ceramics with a relatively inexpensive and perspective armour material. With regard to the second element of armour structure, a new approach has also been found to composition of multilayer fabric and manufacturing technology, which involves the production of a high performance industrial thermo-hydro forming unit, which in liquid, under high pressure and temperature, would thermoform composite armour products (ballistic ceramic plate) of complex configurations. This method gives us the opportunity to

Eutectic Microbonding of Composite Materials Using Microwave Technology

Advanced Materials Research, Jun 23, 2021

The paper aims to report researches in microbonding process of composite magnetic materials using... more The paper aims to report researches in microbonding process of composite magnetic materials using as thermal source the heat produced in base materials by the conversion of the electromagnetic waves with high frequency into thermal energy. This technology can be applied by targeting the base materials with microwaves and taking into account that composite magnetic materials based on ferrites, present good absorbance and conversion properties of the microwaves into heat. For experimental research, the base materials were sintered sampled of raw products obtained from stoichiometric mixtures of 6Fe2O3 + BaCO3. The raw products were obtained by milling and alloying processes using planetary ball mills. The milling and alloying processes have been perfomed in dry environement for homogeneous mixtures and wet environment for mixtures obtained using mechanical alloying. In terms of eutectic alloys used for microbonding, there have been used lead free Sn96,5%+Ag3%+Cu0,5% with melting point around 2170 C. The microbonding process have been perfomed in two steps: first step was focused on prepairing the base materials by cleaning and deposition of eutectic alloys on their surfaces; the second step was the heating of the base materials in microwave field. A microwave generator with adjustable input power from 0 W to 6000 W with a WR340 waveguide have been used as thermal sources. The researches have shown that the base materials were bonded using less than 10 % of microwave power and the eutectic alloys reached the melting temperature în less than 3 seconds when the magnetron was set to full power. A matching load impedance automatic tuner up to 6000 W have been used for increasing the level of absorbed power from nicrowave generator to samples and decreasing the level of rejected power from composite magnetic material to microwave generator. The temperature have been measured using IR pyrometers with range measurement between 0 and 7000 C. The process can be succesfully applied to a large scale for small parts of electrical engines with permanent cermic magnets.

Preliminary Research for Development of MW-TIG Hybrid Welding System

Advanced Materials Research, Jun 23, 2021

The paper aims to report preliminary researches towards to development of new hybrid welding syst... more The paper aims to report preliminary researches towards to development of new hybrid welding system by coupling a microwave beam with a TIG torch. The main research was focused on the designing of hybrid system as well as to establish the heating/welding mechanism by coupling two different thermal sources. Therefore, a specific welding chamber was designed taking into consideration the limitations provided by microwave waveguide technical specs, geometrical shape and dimensions of the TIG torch as well as the temperature monitoring during welding process and video surveillance for data recording. A microwave generator with adjustable power from 0 to 1250 W was coupled with a TIG torch and welding power source in order to establish the main parameters for hybrid system. The preliminary researches reported that the MW-TIG hybrid welding could be applied to eutectic joining of materials using low power (up to 600 W) injected from microwave generator as well as low welding current (up to 20 A). The flow of shielding gas have been established initially to 2 l/m. The research related to stabilization of MW-WIG plasma arc have been studied by increasing the flow of shielding gas up to 10 l/m. The results have shown that the microwave generator and TIG torch can be coupled to obtain hybrid-welding process without any matching tuning devices but with risks for damaging the microwave generator. Further researches will be done in order to design auxiliary devices to optimize the hybrid-welding process and to avoid any unwanted plasma arc discharge from welded base materials to microwave generator. In terms of temperature monitoring, an infrared pyrometer has been used. The IR pyrometer was targeted to the base materials in order to be able to measure their temperature without any influences from plasma arc. The results obtained have shown a stable plasma at average microwave power around 400 W even without any TIG current.

Microwave Heating of Cordierite Ceramic Substrate for After Treatment Systems

Analele Universităţii "Dunărea de Jos" din Galaţi, Dec 28, 2020

Selective catalyst reduction is one of the most affordable and successful technologies aimed at r... more Selective catalyst reduction is one of the most affordable and successful technologies aimed at reducing NOx emissions from diesel engines. However, the reduction process can be achieved if a certain temperature is reached for the ceramic substrate of the catalytic core. The required temperatures for catalytic reaction vary from 250 0 C to 450 0 C depending on the technology applied in the catalytic processes. This paper aims at presenting preliminary research in microwave cordierite heating, which is a type of magnesium aluminium silicate used as ceramic honeycomb substrate (catalyst monolith) in the after treatment system in the automotive industry. The research focused on testing the Mg2Al4Si5O18 composite material (cordierite) for different microwave heating regimes in order to establish the level of microwave power required for fast heating. This application will be subject for the further development of new MW-SCR after treatment systems in order to reduce the NOx emissions at cold start engine or low operating regimes of non-road mobile machinery engines. The ceramic composite material was heated for 5 levels of microwave power, from 600 W to 1400 W, using a 6 kW microwave generator coupled with a matching load impedance tuner, and the temperatures were recorded using an IR pyrometer.

Laser welding of low friction nanostructured sintered composites: technical and environmental aspects

International Journal of Microstructure and Materials Properties, 2010

Low friction materials in nanostructured sintered composites are used for different pairs of movi... more Low friction materials in nanostructured sintered composites are used for different pairs of moving parts of MEMS configuration. The paper aims to present some elements regarding the behaviour of such type of materials in pulsed laser welding process. The influences that are developed during the interaction between the laser beam and the nanostructured composite have been analysed. Major instabilities have been observed and that involved a very accurate choosing of the laser power. The particles have been measured and visualised from the emitted fume by using special extractors that analysed the emitted gases as well. The particles were put in suspension and visualised by using nanosight microscope and they were measured by using a nanosizer. The analysis showed that they were in nanometric domain that meaning higher impact on the human health comparing to the welding of the classic materials, according to the OSHA.

Analysis of Industrial Areas along European Inland Waterways

Advances in Science and Technology, Sep 27, 2021

Significant industrial settlements along the main Europe inland waterways are going to be analyse... more Significant industrial settlements along the main Europe inland waterways are going to be analysed based on NACE codes per port (maritime and inland) in ports and along the waterway. The industrial areas around ports have been analysed and different KPIs were developed, like distance from industrial areas for handling infrastructure, throughput or industrial segments. Furthermore, an analysys concerning the link between the length of the waterways and the land usage areas has been performed as well as the influnce of the population density on the land usage area ratio.

Influence of the Shape of Composites Materials on the Stability of Microwave Heating Processes

Advanced engineering forum, Sep 7, 2021

This paper aims to present preliminary researches on the influence of the shape and dimensions of... more This paper aims to present preliminary researches on the influence of the shape and dimensions of composites materials on the stability of microwave heating. The research was focused on cordierite composite material, which is used as ceramic substrate in selective catalytic reaction for reduction of nitrogen oxide emissions from combustion engines. For experimental program were used different shapes for cordierite material, such as cubic, cylindrical, sphere and rectangular. Based on previous researches where it was demonstrated that an injected microwave power between 600 W and 1200 W, the samples were heated in order to establish which shape is more suitable for fast heating, thermal stability in terms of thermal runaway as well as for avoiding the unwanted microwave plasma initiation.

Analysis of CO2 Emissions for a Supercharged Engine and a Series–Parallel Hybrid System

Atlantis highlights in engineering, 2023

The emissions of CO 2 represent an important factor for the automotive industry in the climate ch... more The emissions of CO 2 represent an important factor for the automotive industry in the climate change at the global level. The paper aims to study the influence of driving conditions on the CO 2 emissions and fuel consumption for two different types of propulsion systems: one conventional propulsion system consisting of a supercharged engine with a low displacement of 998 cm 3 and 88 kW output power and one series-parallel hybrid propulsion system consisting of a naturally aspirated engine of 2487 cm 3 displacement, and 131 kW coupled with an electrical engine of 88 kW.

Differential Thermal Analysis in Microwave Hybrid Field of Some Composite Ceramic Materials

Atlantis highlights in engineering, 2023

Microwave heating is a green technology that provides many advantages over conventional heating. ... more Microwave heating is a green technology that provides many advantages over conventional heating. In this paper, we analyse some composite ceramic materials, formed by barium carbonate and hematite powders. There were used three mixtures with micron, submicron and nanometric particles size. All the mixtures were sintered in microwave hybrid field using a new differential thermal analysis technique. For this type of materials it was necessary to optimize the heating process and has been found that the microwave sintering time is very short, in the order of minutes, compared to resistive heating, which is a great advantage in terms of process productivity. Using differential thermal analysis in microwave hybrid field, the sintering temperatures of the magnetic ceramic materials could be identified. The sintering temperature of the sample from nanometric powder mixture decreased by about 20% compared to the sintering temperature of the sample from micron powder mixture. The use of the nanometric mixtures in experiments is advantageous as it ensures high productivity, low sintering temperatures and very good magnetic parameters.

Competencies for Inland Navigation Crew of LNG-Fueled Ships

Advanced engineering forum, Apr 1, 2018

This paper intends to submit the necessary skills they must possess personnel on ships powered by... more This paper intends to submit the necessary skills they must possess personnel on ships powered by LNG at both operational level (OL) and management level (ML). The study is intended as a complement to the relevant tables developed in previous projects such as STCIN and Platina Tables of Competencies.

Microwave Differential Thermal Analysis Technique of the Fe<sub>2</sub>O<sub>3</sub>+BaCO<sub>3</sub> Homogeneous Mixture

Advanced Materials Research, Oct 1, 2014

The microwave differential thermal analysis (MW-DTA) is a new procedure to evaluate the materials... more The microwave differential thermal analysis (MW-DTA) is a new procedure to evaluate the materials, barium ferrite type M in this paper, according to the phenomena appeared during the material heating. The paper presents a new evaluation technique which is faster and with low energy consumption. The microwaves are used to heat the material, two infrared pyrometers for monitoring the temperatures on the material surface and a temperature regulator where the data are recorded for evaluation. The material, a homogeneous mixture of Fe2O3+BaCO3, is a ceramic material with good absorbance properties, so the heating will be pure microwave heating. The results and the DTA graphic is automatically generated by the temperature recording device based on the data sensed by the infrared pyrometers. The paper presents technical aspect regarding to the microwave heating and temperature measurement in microwave field and how to make differential thermal analysis in microwave field.

Researches Regarding Elaboration of Barium Hexaferrite from Microwave Heating

Solid State Phenomena, May 1, 2012

The paper presents the results of experimental researches on the formation of barium hexaferrite ... more The paper presents the results of experimental researches on the formation of barium hexaferrite type M (BHFM) by microwave heating. The microwave heating process takes only a few minutes to obtain calcined barium ferrite powders. Micronic and nanometric powders of BaCO3 and α-Fe2O3 were used as raw materials. In order to obtain BHFM, the microwave heating process was used with following mixtures: stoichiometric homogeneous mixture of BaCO3 and α-Fe2O3 powders, mechanically alloyed mixtures of BaCO3 and α-Fe2O3 powders for 5 and 20 hours in wet medium using a high energy ball mill Pulverisette 4. Using high energy ball milling, the powder size was turned into nanoscale. After using the microwave heating process it was observed a significant reduction of temperature-time parameters to BHFM formation for mechanically alloyed mixtures compared to homogeneous mixture.

Evaluation of Residual Stress In Specific Welded Nodes of River Ships

Atlantis highlights in engineering, 2023

Rivers ships are complex welded structures, built of specific volume sections. Each volume sectio... more Rivers ships are complex welded structures, built of specific volume sections. Each volume section contains tens or hundreds of nodes, characterized by high restraint conditions. Due to the welding process, each node experiences local concentration of stresses. The paper aims to present a double, analytical and practical, evaluation of the residual stresses in a part of the double bottom deck. It has been built a physical model of such part of the double bottom deck and welding process was applied. The displacement was measured and the residual stress was obtained. It has been concluded that each new welding pass produced lower shrinkage than the previous one. A similar geometrical model was defined and simulated in FEM software. The results confirmed the results of the practical tests. It was, also, found that the cooling between the welding passes produced sudden variations of the displacements, all being in the sense of reducing the opening of the groove.

Microwave Heating of Exhaust Systems from Combustion Engines for Improvement of After treatment Systems

Atlantis highlights in engineering, 2023

The cold start effect of combustion engines leads to high rate of NOx emissions because the gases... more The cold start effect of combustion engines leads to high rate of NOx emissions because the gases temperature of the exhauster is lower than the functioning temperature of selective catalyst reduction systems. This paper aim to present preliminary research, in terms of modelling the thermal field and experimental procedure, for heating the exhaust gases using microwave heating. The experimental procedure was focused on different levels of microwave injected power from 600 W to 3000 W. Two sources of gas were considered in experimental procedure: Corgon with flow rate from 5 l/min to 30 l/min and compressed air at 4 bar pressure. The results of thermal field simulation revealed levels of temperature up to 113°C. The simulation has been validated by experimental procedure where the levels of temperature were 140°C for Corgon at 1800 W microwave injected power and 120°C for compressed air.

Joining Photovoltaic Cell Connection Strips Using Ultra-Acoustic Wave - Resistive Hybrid Heating System

Advanced Materials Research

The manufacture of photovoltaic panels for the production of sustainable energy also involves the... more The manufacture of photovoltaic panels for the production of sustainable energy also involves the stage of electrical connection of the cells in the panel structure. This electrical connection is made by soldering of copper strips on the negative electrode of the cell. During the bonding process, due to the temperature of approximately 220-240°C at which the connecting strip is continuously heated, cracking processes of the upper layer of glass from the cell surface were identified. For this reason, it is necessary either to heat to lower temperatures, a solution that is not viable due to the melting temperature of the solder alloy which usually exceeds 210°C, or a different dosing of the heat flux. The solution proposed in the paper is to create a variable heat flux that allows the melting of the solder alloy, but at the same time to reduce the thermal load of the glass support layer. Through the proposed variant, the energy dosing is done with the help of a heating system consisti...

Study of functional characteristics of the hybrid US-laser bonds

Optoelectronics and Advanced Materials-rapid Communications, 2017

SPECIFIC BEHAVIOUR OF Sn-9Zn LOW FUSION ALLOY USED AS MATERIAL FOR FILAMENT DEDICATED TO FDM PRINTING PROCESS

FDM printing process uses filaments made of polymers. The paper aims to analyze the behaviors of ... more FDM printing process uses filaments made of polymers. The paper aims to analyze the behaviors of Sn-9Zn low fusion alloy as potential material for elaboration of metallic filaments for FDM process. Sn9Zn has low melting point, which is below the maximum temperature reached by all common FDM printers. No alterations of the heater component of a printer are required when replace the polymeric filaments with Sn-9Zn filament. Different from ABS and PLA, Sn-9Zn is softer and has lower stiffness. Lower stiffness proved to involve difficulties in the transfer of the filament from the spool to the hot-end. Inside the hot-end the material is very fluid and, due to its transfer speed, the filament fills the heating chamber and the nozzle. That creates a resistance to the transfer process and the filament suffers deformation and even blockages. Specific correlation of the nozzle diameter with the heating temperature and the transfer speed was considered. Increasing of the nozzle diameter from ...

Simulation of Thermal Field in Eutectic Microwave Bonding for Electrical Connection of Photovoltaic Cells

Advanced Materials Research, Jun 6, 2022

Sustainable development requires green energy and low carbon footprint in manufacturing sector of... more Sustainable development requires green energy and low carbon footprint in manufacturing sector of photovoltaic systems. The electrical connections of photovoltaic cells need to have low electrical resistance in order to reduce the electrical losses and therefore to improve the performance of the photovoltaic panels. This paper aims to present researches related to bonding of wires that connect solar cells by using microwave technology. The microwave bonding has the main advantage that offers fast bonding but, in the same time, this technology does not offer stability of the thermal heating. Two different unwanted phenomena like thermal runaway and plasma arc discharge often lead to the damaging of copper and aluminum wires used in electrical connection. The study presented in this paper is focused on simulation of the thermal field developed in copper wires in order to optimize the bonding process and increase the quality of products. The simulation of the thermal field has been done using Fourier equations for conducting heating in copper materials and eutectic alloys. The simulation model has been validated through experimental heating using a 6 kW water-cooled microwave generator controlled by a matching load auto-tuner for best transfer of the power from generator to copper wires. The temperature has been measured in real time using an infrared pyrometer for metals with 2.3 μm spectral range and measurement range between 0o C and 7000 C. The study is finalized with elaboration of mathematical model for microwave-injected power as function for temperature developed in copper wires that can be applied with success in further microwave bonding applications of copper wires. In addition, the electrical resistance of bonded wires was measured in order to collect feedback for improving the microwave bonding process.

Microstructure of magnetite doped elastomers investigated by SAXS and SANS

We present some recent results on the SAXS and SANS investigations of the magnetic elastomers. Sa... more We present some recent results on the SAXS and SANS investigations of the magnetic elastomers. Samples were obtained by polymerizing dimethylsiloxane with Fe 3 O 4 ferrofluid in a magnetic field and without magnetic field and characterized by XRD, SANS and SAXS. The SAXS maximum at large angles, obtained from magnetic elastomers, was fitted by using a Pseudo-Voigt function. It was found that the Fe 3 O 4 particles lead to a significant change of the local structure of elastomer, meaning the decrease of the quasi-crystalline phase and the micro-strains into the matrix. The average particle size obtained from SANS measurements agrees well with the average particle size determined by XRD and SAXS analysis. The splitting of the SANS intensity owing to an additional scattering in zero field reflects the existence of magnetic correlations inside the Q region of 0.005 Å -1 < Q < 0.02 Å -1 .

Hybrid heating in Fused Filament Fabrication process

Research Square (Research Square), Apr 4, 2024

Changing the heating regime of the polymer during printing by the Fused Filament Fabrication (FFF... more Changing the heating regime of the polymer during printing by the Fused Filament Fabrication (FFF) process can produce changes in the behavior of the polymer, but also changes in the characteristics of the printed product. The work proposes to replace the traditional resistive heating system with two hybrid heating systems that bring an additional temperature of 120-160 o C: resistive and hot air jet, resistive and infrared radiation. The samples printed by using the two hybrid heating systems were DSC analyzed and visual tested. The filaments used for the experimental program were commercial filaments of ABS and PLA. A model to evaluate the melting of the polymer during the printing process was proposed, and it was experimentally confirmed. The visual testing revealed that the printed lattice's structure is characterized by lower dimension voids of the structure, being built by depositions that are not circular in section, but flattened, due to the longer time in viscous / partially molten state. The elongation viscosity and the storage modulus decreased with about 10%, being slightly lower in the case of the infrared radiation heat source. The glassy temperature remained unchanged; the mobility of the molecules being not affected by the supplementary heat. The energy consumed to form the crystals is not changed by the supplementary heat. Mechanical behavior of the printed piece, during compression tests, was also influenced by the addition of the second heat source. For both materials a decrease in deformability is recorded as the temperature of the hot air jet increases. Highlights 1. Hybrid source for heating in FFF printing 2. Influence of hybrid heating on the characteristics of the deposited material 3. Thermal field in the deposited material 4. Modelling of thermal field 5. Changing in DSC thermograms for PLA and for ABS due to hybrid heating Keywords hybrid heating; DSC analysis; lattices structure; thermal field; thermal and mechanical characteristics

Creation of New Generation Titanium Diboride Composite Armour Material

NATO science for peace and security series, 2020

The next generation Armour Piercing Bullet with Tungsten Carbide core has been introduced into th... more The next generation Armour Piercing Bullet with Tungsten Carbide core has been introduced into the world's leading military forces by the beginning of the twenty-first century, and later, into the Russian army, which has resulted in a sharp increase in penetrability of the existing standard composite armour plates. The only armour system that effectively stops these bullets is a combined structure obtained through a hot-pressing technology and composed of multilayer fabric made of highmolecular organic fibres. Despite the high armour properties of the above-mentioned structure, its components (separately and together) have some negative sides as well: high cost, low production capacity and low firmness of armour ceramics, which hinders its widespread use in personal protective equipment and in armoured combat vehicles as well. Therefore, there was a need to find new approaches in processing technologies of protective structure and its new components in order to create a new generation armour material for ceramic armour characterized by high hardness and strength (not less than boron carbide), low cost and high capacity and with the following physical-mechanical properties: micro hardness-3600-3800 kg/mm 2 ; bending strength 70-80 kg/mm 2 ; density-4.0-4.5 g/cm 3. The obtained results will allow us to replace the boron carbide ceramics with a relatively inexpensive and perspective armour material. With regard to the second element of armour structure, a new approach has also been found to composition of multilayer fabric and manufacturing technology, which involves the production of a high performance industrial thermo-hydro forming unit, which in liquid, under high pressure and temperature, would thermoform composite armour products (ballistic ceramic plate) of complex configurations. This method gives us the opportunity to

Eutectic Microbonding of Composite Materials Using Microwave Technology

Advanced Materials Research, Jun 23, 2021

The paper aims to report researches in microbonding process of composite magnetic materials using... more The paper aims to report researches in microbonding process of composite magnetic materials using as thermal source the heat produced in base materials by the conversion of the electromagnetic waves with high frequency into thermal energy. This technology can be applied by targeting the base materials with microwaves and taking into account that composite magnetic materials based on ferrites, present good absorbance and conversion properties of the microwaves into heat. For experimental research, the base materials were sintered sampled of raw products obtained from stoichiometric mixtures of 6Fe2O3 + BaCO3. The raw products were obtained by milling and alloying processes using planetary ball mills. The milling and alloying processes have been perfomed in dry environement for homogeneous mixtures and wet environment for mixtures obtained using mechanical alloying. In terms of eutectic alloys used for microbonding, there have been used lead free Sn96,5%+Ag3%+Cu0,5% with melting point around 2170 C. The microbonding process have been perfomed in two steps: first step was focused on prepairing the base materials by cleaning and deposition of eutectic alloys on their surfaces; the second step was the heating of the base materials in microwave field. A microwave generator with adjustable input power from 0 W to 6000 W with a WR340 waveguide have been used as thermal sources. The researches have shown that the base materials were bonded using less than 10 % of microwave power and the eutectic alloys reached the melting temperature în less than 3 seconds when the magnetron was set to full power. A matching load impedance automatic tuner up to 6000 W have been used for increasing the level of absorbed power from nicrowave generator to samples and decreasing the level of rejected power from composite magnetic material to microwave generator. The temperature have been measured using IR pyrometers with range measurement between 0 and 7000 C. The process can be succesfully applied to a large scale for small parts of electrical engines with permanent cermic magnets.

Preliminary Research for Development of MW-TIG Hybrid Welding System

Advanced Materials Research, Jun 23, 2021

The paper aims to report preliminary researches towards to development of new hybrid welding syst... more The paper aims to report preliminary researches towards to development of new hybrid welding system by coupling a microwave beam with a TIG torch. The main research was focused on the designing of hybrid system as well as to establish the heating/welding mechanism by coupling two different thermal sources. Therefore, a specific welding chamber was designed taking into consideration the limitations provided by microwave waveguide technical specs, geometrical shape and dimensions of the TIG torch as well as the temperature monitoring during welding process and video surveillance for data recording. A microwave generator with adjustable power from 0 to 1250 W was coupled with a TIG torch and welding power source in order to establish the main parameters for hybrid system. The preliminary researches reported that the MW-TIG hybrid welding could be applied to eutectic joining of materials using low power (up to 600 W) injected from microwave generator as well as low welding current (up to 20 A). The flow of shielding gas have been established initially to 2 l/m. The research related to stabilization of MW-WIG plasma arc have been studied by increasing the flow of shielding gas up to 10 l/m. The results have shown that the microwave generator and TIG torch can be coupled to obtain hybrid-welding process without any matching tuning devices but with risks for damaging the microwave generator. Further researches will be done in order to design auxiliary devices to optimize the hybrid-welding process and to avoid any unwanted plasma arc discharge from welded base materials to microwave generator. In terms of temperature monitoring, an infrared pyrometer has been used. The IR pyrometer was targeted to the base materials in order to be able to measure their temperature without any influences from plasma arc. The results obtained have shown a stable plasma at average microwave power around 400 W even without any TIG current.

Microwave Heating of Cordierite Ceramic Substrate for After Treatment Systems

Analele Universităţii "Dunărea de Jos" din Galaţi, Dec 28, 2020

Selective catalyst reduction is one of the most affordable and successful technologies aimed at r... more Selective catalyst reduction is one of the most affordable and successful technologies aimed at reducing NOx emissions from diesel engines. However, the reduction process can be achieved if a certain temperature is reached for the ceramic substrate of the catalytic core. The required temperatures for catalytic reaction vary from 250 0 C to 450 0 C depending on the technology applied in the catalytic processes. This paper aims at presenting preliminary research in microwave cordierite heating, which is a type of magnesium aluminium silicate used as ceramic honeycomb substrate (catalyst monolith) in the after treatment system in the automotive industry. The research focused on testing the Mg2Al4Si5O18 composite material (cordierite) for different microwave heating regimes in order to establish the level of microwave power required for fast heating. This application will be subject for the further development of new MW-SCR after treatment systems in order to reduce the NOx emissions at cold start engine or low operating regimes of non-road mobile machinery engines. The ceramic composite material was heated for 5 levels of microwave power, from 600 W to 1400 W, using a 6 kW microwave generator coupled with a matching load impedance tuner, and the temperatures were recorded using an IR pyrometer.

Laser welding of low friction nanostructured sintered composites: technical and environmental aspects

International Journal of Microstructure and Materials Properties, 2010

Low friction materials in nanostructured sintered composites are used for different pairs of movi... more Low friction materials in nanostructured sintered composites are used for different pairs of moving parts of MEMS configuration. The paper aims to present some elements regarding the behaviour of such type of materials in pulsed laser welding process. The influences that are developed during the interaction between the laser beam and the nanostructured composite have been analysed. Major instabilities have been observed and that involved a very accurate choosing of the laser power. The particles have been measured and visualised from the emitted fume by using special extractors that analysed the emitted gases as well. The particles were put in suspension and visualised by using nanosight microscope and they were measured by using a nanosizer. The analysis showed that they were in nanometric domain that meaning higher impact on the human health comparing to the welding of the classic materials, according to the OSHA.

Analysis of Industrial Areas along European Inland Waterways

Advances in Science and Technology, Sep 27, 2021

Significant industrial settlements along the main Europe inland waterways are going to be analyse... more Significant industrial settlements along the main Europe inland waterways are going to be analysed based on NACE codes per port (maritime and inland) in ports and along the waterway. The industrial areas around ports have been analysed and different KPIs were developed, like distance from industrial areas for handling infrastructure, throughput or industrial segments. Furthermore, an analysys concerning the link between the length of the waterways and the land usage areas has been performed as well as the influnce of the population density on the land usage area ratio.

Influence of the Shape of Composites Materials on the Stability of Microwave Heating Processes

Advanced engineering forum, Sep 7, 2021

This paper aims to present preliminary researches on the influence of the shape and dimensions of... more This paper aims to present preliminary researches on the influence of the shape and dimensions of composites materials on the stability of microwave heating. The research was focused on cordierite composite material, which is used as ceramic substrate in selective catalytic reaction for reduction of nitrogen oxide emissions from combustion engines. For experimental program were used different shapes for cordierite material, such as cubic, cylindrical, sphere and rectangular. Based on previous researches where it was demonstrated that an injected microwave power between 600 W and 1200 W, the samples were heated in order to establish which shape is more suitable for fast heating, thermal stability in terms of thermal runaway as well as for avoiding the unwanted microwave plasma initiation.

Analysis of CO2 Emissions for a Supercharged Engine and a Series–Parallel Hybrid System

Atlantis highlights in engineering, 2023

The emissions of CO 2 represent an important factor for the automotive industry in the climate ch... more The emissions of CO 2 represent an important factor for the automotive industry in the climate change at the global level. The paper aims to study the influence of driving conditions on the CO 2 emissions and fuel consumption for two different types of propulsion systems: one conventional propulsion system consisting of a supercharged engine with a low displacement of 998 cm 3 and 88 kW output power and one series-parallel hybrid propulsion system consisting of a naturally aspirated engine of 2487 cm 3 displacement, and 131 kW coupled with an electrical engine of 88 kW.

Differential Thermal Analysis in Microwave Hybrid Field of Some Composite Ceramic Materials

Atlantis highlights in engineering, 2023

Microwave heating is a green technology that provides many advantages over conventional heating. ... more Microwave heating is a green technology that provides many advantages over conventional heating. In this paper, we analyse some composite ceramic materials, formed by barium carbonate and hematite powders. There were used three mixtures with micron, submicron and nanometric particles size. All the mixtures were sintered in microwave hybrid field using a new differential thermal analysis technique. For this type of materials it was necessary to optimize the heating process and has been found that the microwave sintering time is very short, in the order of minutes, compared to resistive heating, which is a great advantage in terms of process productivity. Using differential thermal analysis in microwave hybrid field, the sintering temperatures of the magnetic ceramic materials could be identified. The sintering temperature of the sample from nanometric powder mixture decreased by about 20% compared to the sintering temperature of the sample from micron powder mixture. The use of the nanometric mixtures in experiments is advantageous as it ensures high productivity, low sintering temperatures and very good magnetic parameters.

Competencies for Inland Navigation Crew of LNG-Fueled Ships

Advanced engineering forum, Apr 1, 2018

This paper intends to submit the necessary skills they must possess personnel on ships powered by... more This paper intends to submit the necessary skills they must possess personnel on ships powered by LNG at both operational level (OL) and management level (ML). The study is intended as a complement to the relevant tables developed in previous projects such as STCIN and Platina Tables of Competencies.

Microwave Differential Thermal Analysis Technique of the Fe<sub>2</sub>O<sub>3</sub>+BaCO<sub>3</sub> Homogeneous Mixture

Advanced Materials Research, Oct 1, 2014

The microwave differential thermal analysis (MW-DTA) is a new procedure to evaluate the materials... more The microwave differential thermal analysis (MW-DTA) is a new procedure to evaluate the materials, barium ferrite type M in this paper, according to the phenomena appeared during the material heating. The paper presents a new evaluation technique which is faster and with low energy consumption. The microwaves are used to heat the material, two infrared pyrometers for monitoring the temperatures on the material surface and a temperature regulator where the data are recorded for evaluation. The material, a homogeneous mixture of Fe2O3+BaCO3, is a ceramic material with good absorbance properties, so the heating will be pure microwave heating. The results and the DTA graphic is automatically generated by the temperature recording device based on the data sensed by the infrared pyrometers. The paper presents technical aspect regarding to the microwave heating and temperature measurement in microwave field and how to make differential thermal analysis in microwave field.

Researches Regarding Elaboration of Barium Hexaferrite from Microwave Heating

Solid State Phenomena, May 1, 2012

The paper presents the results of experimental researches on the formation of barium hexaferrite ... more The paper presents the results of experimental researches on the formation of barium hexaferrite type M (BHFM) by microwave heating. The microwave heating process takes only a few minutes to obtain calcined barium ferrite powders. Micronic and nanometric powders of BaCO3 and α-Fe2O3 were used as raw materials. In order to obtain BHFM, the microwave heating process was used with following mixtures: stoichiometric homogeneous mixture of BaCO3 and α-Fe2O3 powders, mechanically alloyed mixtures of BaCO3 and α-Fe2O3 powders for 5 and 20 hours in wet medium using a high energy ball mill Pulverisette 4. Using high energy ball milling, the powder size was turned into nanoscale. After using the microwave heating process it was observed a significant reduction of temperature-time parameters to BHFM formation for mechanically alloyed mixtures compared to homogeneous mixture.

Evaluation of Residual Stress In Specific Welded Nodes of River Ships

Atlantis highlights in engineering, 2023

Rivers ships are complex welded structures, built of specific volume sections. Each volume sectio... more Rivers ships are complex welded structures, built of specific volume sections. Each volume section contains tens or hundreds of nodes, characterized by high restraint conditions. Due to the welding process, each node experiences local concentration of stresses. The paper aims to present a double, analytical and practical, evaluation of the residual stresses in a part of the double bottom deck. It has been built a physical model of such part of the double bottom deck and welding process was applied. The displacement was measured and the residual stress was obtained. It has been concluded that each new welding pass produced lower shrinkage than the previous one. A similar geometrical model was defined and simulated in FEM software. The results confirmed the results of the practical tests. It was, also, found that the cooling between the welding passes produced sudden variations of the displacements, all being in the sense of reducing the opening of the groove.

Microwave Heating of Exhaust Systems from Combustion Engines for Improvement of After treatment Systems

Atlantis highlights in engineering, 2023

The cold start effect of combustion engines leads to high rate of NOx emissions because the gases... more The cold start effect of combustion engines leads to high rate of NOx emissions because the gases temperature of the exhauster is lower than the functioning temperature of selective catalyst reduction systems. This paper aim to present preliminary research, in terms of modelling the thermal field and experimental procedure, for heating the exhaust gases using microwave heating. The experimental procedure was focused on different levels of microwave injected power from 600 W to 3000 W. Two sources of gas were considered in experimental procedure: Corgon with flow rate from 5 l/min to 30 l/min and compressed air at 4 bar pressure. The results of thermal field simulation revealed levels of temperature up to 113°C. The simulation has been validated by experimental procedure where the levels of temperature were 140°C for Corgon at 1800 W microwave injected power and 120°C for compressed air.

Joining Photovoltaic Cell Connection Strips Using Ultra-Acoustic Wave - Resistive Hybrid Heating System

Advanced Materials Research

The manufacture of photovoltaic panels for the production of sustainable energy also involves the... more The manufacture of photovoltaic panels for the production of sustainable energy also involves the stage of electrical connection of the cells in the panel structure. This electrical connection is made by soldering of copper strips on the negative electrode of the cell. During the bonding process, due to the temperature of approximately 220-240°C at which the connecting strip is continuously heated, cracking processes of the upper layer of glass from the cell surface were identified. For this reason, it is necessary either to heat to lower temperatures, a solution that is not viable due to the melting temperature of the solder alloy which usually exceeds 210°C, or a different dosing of the heat flux. The solution proposed in the paper is to create a variable heat flux that allows the melting of the solder alloy, but at the same time to reduce the thermal load of the glass support layer. Through the proposed variant, the energy dosing is done with the help of a heating system consisti...

Study of functional characteristics of the hybrid US-laser bonds

Optoelectronics and Advanced Materials-rapid Communications, 2017

SPECIFIC BEHAVIOUR OF Sn-9Zn LOW FUSION ALLOY USED AS MATERIAL FOR FILAMENT DEDICATED TO FDM PRINTING PROCESS

FDM printing process uses filaments made of polymers. The paper aims to analyze the behaviors of ... more FDM printing process uses filaments made of polymers. The paper aims to analyze the behaviors of Sn-9Zn low fusion alloy as potential material for elaboration of metallic filaments for FDM process. Sn9Zn has low melting point, which is below the maximum temperature reached by all common FDM printers. No alterations of the heater component of a printer are required when replace the polymeric filaments with Sn-9Zn filament. Different from ABS and PLA, Sn-9Zn is softer and has lower stiffness. Lower stiffness proved to involve difficulties in the transfer of the filament from the spool to the hot-end. Inside the hot-end the material is very fluid and, due to its transfer speed, the filament fills the heating chamber and the nozzle. That creates a resistance to the transfer process and the filament suffers deformation and even blockages. Specific correlation of the nozzle diameter with the heating temperature and the transfer speed was considered. Increasing of the nozzle diameter from ...

Simulation of Thermal Field in Eutectic Microwave Bonding for Electrical Connection of Photovoltaic Cells

Advanced Materials Research, Jun 6, 2022

Sustainable development requires green energy and low carbon footprint in manufacturing sector of... more Sustainable development requires green energy and low carbon footprint in manufacturing sector of photovoltaic systems. The electrical connections of photovoltaic cells need to have low electrical resistance in order to reduce the electrical losses and therefore to improve the performance of the photovoltaic panels. This paper aims to present researches related to bonding of wires that connect solar cells by using microwave technology. The microwave bonding has the main advantage that offers fast bonding but, in the same time, this technology does not offer stability of the thermal heating. Two different unwanted phenomena like thermal runaway and plasma arc discharge often lead to the damaging of copper and aluminum wires used in electrical connection. The study presented in this paper is focused on simulation of the thermal field developed in copper wires in order to optimize the bonding process and increase the quality of products. The simulation of the thermal field has been done using Fourier equations for conducting heating in copper materials and eutectic alloys. The simulation model has been validated through experimental heating using a 6 kW water-cooled microwave generator controlled by a matching load auto-tuner for best transfer of the power from generator to copper wires. The temperature has been measured in real time using an infrared pyrometer for metals with 2.3 μm spectral range and measurement range between 0o C and 7000 C. The study is finalized with elaboration of mathematical model for microwave-injected power as function for temperature developed in copper wires that can be applied with success in further microwave bonding applications of copper wires. In addition, the electrical resistance of bonded wires was measured in order to collect feedback for improving the microwave bonding process.