Satyam K Bhuyan | Arba Minch University (original) (raw)

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Papers by Satyam K Bhuyan

Energy Harvesting and Systems, 2019

Microelectromechanical systems (MEMS) are micrometre-size systems that are capable of transformin... more Microelectromechanical systems (MEMS) are micrometre-size systems that are capable of transforming electrical signals to mechanical signals. In this paper, the use of MEMS devices as a method for harvesting waste heat is explored. A background for the technology and methods is discussed and a method proposed for a working device based upon a thermally heated bimorph actu-ated by waste radiation alone is investigated. A chopper interrupts the radiant energy inducing an oscillation in the bimorph temperature and thus creates a mechanical motion which can be taken advantage of using piezo-electric materials. Difficulties in harvesting radiant energy with this method are highlighted and suggestions for non-passive energy generation are made based on the outlined principles.

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Biobased polymers produced from renewable and inexpensive natural resources, such as natural oils... more Biobased polymers produced from renewable and inexpensive natural resources, such as natural oils, have drawn considerable attention over the past decades, due to their low cost, ready availability, environmental compatibility, and their inherent biodegradability. In this study, the micro/nanotribo-logical wear behavior of biopolymers with different crosslinking densities prepared from low saturated soybean oil (LSS) by cationic copolymerization with divinyl benzene and polystyrene are evaluated and compared. Microtribological measurements were performed using a ball-on-flat reciprocating microtribometer using two different probes À 1.2 mm radius Si 3 N 4 spherical probe and a 100 mm radius conical diamond probe with 901 cone angle. Nanoscale wear tests were performed using a DLC coated antimony (n) doped silicon probe of radius $ 200 nm in an atomic force microscope (AFM). Wear volumes were estimated from AFM topography maps of groove geometry and wear coefficients were evaluated for the materials. Elastic modulus and hardness information were evaluated using nanoindentation tests. Correlations between crosslinking density and observed wear behavior across scales are discussed. These results provide some insight into the wear behavior of soybean oil-based polymers.

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In this study, the friction and the wear behavior of norbornene-based polymers prepared by ring-o... more In this study, the friction and the wear behavior of norbornene-based polymers prepared by ring-opening metathesis polymerization (ROMP) reaction are evaluated as a function of the crosslinking density. Tri-bological measurements were performed using a ball-on-flat reciprocating microtribometer. Friction and wear experiments under dry sliding were evaluated using a 1.2 mm radius Si 3 N 4 spherical probe as well as a 100 m radius conical diamond probe with a 90 • cone angle. Wear experiments were conducted at constant normal loads for 100–500 reciprocating cycles. Wear depths were estimated from wear grooves using a contact profilometer, and scanning electron microscopy was used to elucidate deformation mechanisms in the various samples. Correlation between the crosslinking density and the wear behavior were observed. Crown

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Novel biobased nanocomposites have been prepared by the cationic copolymerization of conjugated l... more Novel biobased nanocomposites have been prepared by the cationic copolymerization of conjugated low saturated soybean oil with styrene and divinylbenzene, and a reactive organomodified montmo-rillonite (VMMT) clay as reinforcing phase. Microscale tribological measurements were performed on samples with different concentration of VMMT (0%, 1% and 5%, w/w) using a ball-on-flat reciprocating microtribometer. Friction and wear behavior during dry sliding were evaluated using spherical (1.2 mm radius) steel probe as well as a conical (100 m radius, 90 • cone angle) diamond probe. Friction behavior was evaluated from single strokes at ramped normal loads, whereas wear experiments were evaluated from 10 to 1000 reciprocating cycles at fixed normal loads. Contact profilometry and scanning electron microscopy of wear tracks were used to elucidate deformation mechanisms in the various samples.

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In this study, the friction and wear behavior of soybean oil-based polymers prepared by cationic ... more In this study, the friction and wear behavior of soybean oil-based polymers prepared by cationic polymerization of low saturated soybean oil (LSS) with divinyl benzene and polystyrene are evaluated as a function of crosslink density. Tribological measurements were performed on samples of three crosslink densities (10%, 15% and 20% of crosslinking agent concentration by weight) using a ball-on-flat reciprocating microtribometer with normal loads ranging from 0 to 800 mN. Friction and wear behavior during dry sliding was evaluated using a spherical (1.2 mm radius) silicon nitride probe as well as a conical (100 m radius, 90 • cone angle) diamond probe. Friction behavior was evaluated from single strokes at ramped normal loads, whereas wear experiments were evaluated from 10 to 500 reciprocating cycles at fixed normal loads. All samples showed comparable coefficients of friction. In general a higher crosslinking density resulted in lower adhesive wear. Increased abrasive wear was observed for the lowest and highest crosslinking densities. Atomic force microscopy and scanning electron microscopy of wear tracks were used to elucidate deformation mechanisms in the various samples. These results provide some insight into the friction and wear behavior of soybean oil-based polymers.

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Microscale friction tests were utilized to evaluate the boundary lubrication behavior of three se... more Microscale friction tests were utilized to evaluate the boundary lubrication behavior of three sets of branched compounds and their corresponding linear compounds. The performances of the compounds were compared to that of lipid-based saturated and unsaturated acids, esters and alcohols as well as to that of commercial synthetic lubricant formulations. At low concentrations ($0.5%) in paraffin oil and for the load conditions used, the branched compounds showed minor differences in friction behavior as compared to their linear counterparts. The ester compounds by comparison showed higher friction behavior than alcohols and acids.

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In this study, the tribological properties of tung oil-based polymers synthesized by the cationic... more In this study, the tribological properties of tung oil-based polymers synthesized by the cationic copolymerization of tung oil with divinylbenzene and styrene are evaluated as a function of crosslinking density. Tribological measurements were performed using a ball-on-flat reciprocating microtribometer on samples with three crosslinking densities of 20%, 30% and 40% by weight of the crosslinking agent. Friction and wear characteristics during dry sliding were evaluated using a spherical (1.2 mm radius) silicon nitride probe as well as a conical (100 mm radius, 901 cone angle) diamond probe. Microscale friction behavior was evaluated from single strokes at ramped normal loads, whereas wear experiments were evaluated from 100 to 500 reciprocating cycles at fixed normal loads. Elastic modulus and hardness information were evaluated using nanoindentation tests. Scanning electron microscopy of wear tracks was used to elucidate deformation mechanisms in the various samples. All samples showed friction coefficients ranging from 0.06 to 0.49. It was found that a higher crosslinking density resulted in lower abrasive wear due to increased hardness. These results provide some insight into the friction and wear behavior of tung oil-based polymers.

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Thermosetting composites have been prepared by the use of a biobased resin and spent germ filler,... more Thermosetting composites have been prepared by the use of a biobased resin and spent germ filler, which is a byproduct from a wet ethanol production plant. Microscale tribological measurements were performed on samples with different concentrations of the filler as well as the crosslinker using a ball-on-flat reciprocating microtribometer. Microscale friction and wear behavior during dry sliding were evaluated using a spherical silicon nitride probe (radius 1.2 mm) and a conical diamond (radius 100 mm, cone angle 901) probe to impose different contact conditions. Finally, a pin-on-disc tribometer was used to study the macroscale wear properties at high loads against an alumina pin. Scanning electron microscopy (SEM) images of wear tracks on the samples were obtained to elucidate deformation mechanisms. All samples showed evidence of abrasive wear in both micro-and macro-scales. It was found that an increase in the concentration of the filler resulted in higher friction coefficients against Si 3 N 4 , while an increase in the concentration of the crosslinker lowered the abrasive wear depth. These results provide some insight into the effectiveness of using biobased spent germ–tung oil polymer composites as potential tribomaterials.

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Nanoindentation-induced phase transformations in both crystalline silicon (c-Si) (100) and ion-im... more Nanoindentation-induced phase transformations in both crystalline silicon (c-Si) (100) and ion-implanted amorphous silicon have been studied at temperatures up to 200 °C. The region under the indenter undergoes rapid volume expansion at temperatures above 125 °C during unloading, which is indicated by " bowing " behavior in the load–displacement curve. Polycrystalline Si-I is the predominant end phase for indentation in crystalline silicon whereas high-pressure Si-III/Si-XII phases are the result of indentation in amorphous silicon. We suggest that the Si-II phase is unstable in a c-Si matrix at elevated temperatures and can directly transform to Si-I during the early stages of unloading.

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Macromolecular Materials and Engineering, 2011

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Journal of the American Oil Chemists' Society, 2010

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The motion of the triple line during the debonding of a soft viscoelastic adhesive from a rigid p... more The motion of the triple line during the debonding of a soft viscoelastic adhesive from a rigid polymer surface has been investigated quantitatively. In order to make the debonding geometry simpler than the probe tack test, a new technique, called the sticky wedge test, has been developed where the probe is constituted by a horizontal cylinder instead of a flat punch. The crack propagates in the elongated contact area between the cylinder and the flat surface, thereby, allowing us to measure optically in situ the crack-tip velocity and the receding contact angle of the debonding adhesive. Two model pressure sensitive adhesives (PSA) based on poly(n-butyl acrylate-co-acrylic acid) with different molecular weights and branching levels and four polymer substrates (rubbery or glassy at room temperature) were used. Due to the soft and incompressible nature of the adhesive, the strain energy release rate for this test geometry has been estimated by the equations for the pure shear test geometry. The results show three main new insights: first, despite significant approximations, this novel approach holds promise to characterize more quantitatively the interfacial crack propagation between soft viscoelastic solids and hard surfaces and the relationship between the applied energy release rate G and the crack-tip velocity v has been reliably established for eight combinations of the model viscoelastic adhesives and surfaces. Second, at equivalent values of the thermodynamic work of adhesion, the adhesion energy of both the adhesives against the rubbery surface was much lower than that against the glassy polymers. Third, surprisingly, the measured receding contact angle of debonding was close to 90 for all adhesive/ surface combinations used.

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Energy Harvesting and Systems, 2019

Microelectromechanical systems (MEMS) are micrometre-size systems that are capable of transformin... more Microelectromechanical systems (MEMS) are micrometre-size systems that are capable of transforming electrical signals to mechanical signals. In this paper, the use of MEMS devices as a method for harvesting waste heat is explored. A background for the technology and methods is discussed and a method proposed for a working device based upon a thermally heated bimorph actu-ated by waste radiation alone is investigated. A chopper interrupts the radiant energy inducing an oscillation in the bimorph temperature and thus creates a mechanical motion which can be taken advantage of using piezo-electric materials. Difficulties in harvesting radiant energy with this method are highlighted and suggestions for non-passive energy generation are made based on the outlined principles.

Bookmarks Related papers MentionsView impact

Biobased polymers produced from renewable and inexpensive natural resources, such as natural oils... more Biobased polymers produced from renewable and inexpensive natural resources, such as natural oils, have drawn considerable attention over the past decades, due to their low cost, ready availability, environmental compatibility, and their inherent biodegradability. In this study, the micro/nanotribo-logical wear behavior of biopolymers with different crosslinking densities prepared from low saturated soybean oil (LSS) by cationic copolymerization with divinyl benzene and polystyrene are evaluated and compared. Microtribological measurements were performed using a ball-on-flat reciprocating microtribometer using two different probes À 1.2 mm radius Si 3 N 4 spherical probe and a 100 mm radius conical diamond probe with 901 cone angle. Nanoscale wear tests were performed using a DLC coated antimony (n) doped silicon probe of radius $ 200 nm in an atomic force microscope (AFM). Wear volumes were estimated from AFM topography maps of groove geometry and wear coefficients were evaluated for the materials. Elastic modulus and hardness information were evaluated using nanoindentation tests. Correlations between crosslinking density and observed wear behavior across scales are discussed. These results provide some insight into the wear behavior of soybean oil-based polymers.

Bookmarks Related papers MentionsView impact

In this study, the friction and the wear behavior of norbornene-based polymers prepared by ring-o... more In this study, the friction and the wear behavior of norbornene-based polymers prepared by ring-opening metathesis polymerization (ROMP) reaction are evaluated as a function of the crosslinking density. Tri-bological measurements were performed using a ball-on-flat reciprocating microtribometer. Friction and wear experiments under dry sliding were evaluated using a 1.2 mm radius Si 3 N 4 spherical probe as well as a 100 m radius conical diamond probe with a 90 • cone angle. Wear experiments were conducted at constant normal loads for 100–500 reciprocating cycles. Wear depths were estimated from wear grooves using a contact profilometer, and scanning electron microscopy was used to elucidate deformation mechanisms in the various samples. Correlation between the crosslinking density and the wear behavior were observed. Crown

Bookmarks Related papers MentionsView impact

Novel biobased nanocomposites have been prepared by the cationic copolymerization of conjugated l... more Novel biobased nanocomposites have been prepared by the cationic copolymerization of conjugated low saturated soybean oil with styrene and divinylbenzene, and a reactive organomodified montmo-rillonite (VMMT) clay as reinforcing phase. Microscale tribological measurements were performed on samples with different concentration of VMMT (0%, 1% and 5%, w/w) using a ball-on-flat reciprocating microtribometer. Friction and wear behavior during dry sliding were evaluated using spherical (1.2 mm radius) steel probe as well as a conical (100 m radius, 90 • cone angle) diamond probe. Friction behavior was evaluated from single strokes at ramped normal loads, whereas wear experiments were evaluated from 10 to 1000 reciprocating cycles at fixed normal loads. Contact profilometry and scanning electron microscopy of wear tracks were used to elucidate deformation mechanisms in the various samples.

Bookmarks Related papers MentionsView impact

In this study, the friction and wear behavior of soybean oil-based polymers prepared by cationic ... more In this study, the friction and wear behavior of soybean oil-based polymers prepared by cationic polymerization of low saturated soybean oil (LSS) with divinyl benzene and polystyrene are evaluated as a function of crosslink density. Tribological measurements were performed on samples of three crosslink densities (10%, 15% and 20% of crosslinking agent concentration by weight) using a ball-on-flat reciprocating microtribometer with normal loads ranging from 0 to 800 mN. Friction and wear behavior during dry sliding was evaluated using a spherical (1.2 mm radius) silicon nitride probe as well as a conical (100 m radius, 90 • cone angle) diamond probe. Friction behavior was evaluated from single strokes at ramped normal loads, whereas wear experiments were evaluated from 10 to 500 reciprocating cycles at fixed normal loads. All samples showed comparable coefficients of friction. In general a higher crosslinking density resulted in lower adhesive wear. Increased abrasive wear was observed for the lowest and highest crosslinking densities. Atomic force microscopy and scanning electron microscopy of wear tracks were used to elucidate deformation mechanisms in the various samples. These results provide some insight into the friction and wear behavior of soybean oil-based polymers.

Bookmarks Related papers MentionsView impact

Microscale friction tests were utilized to evaluate the boundary lubrication behavior of three se... more Microscale friction tests were utilized to evaluate the boundary lubrication behavior of three sets of branched compounds and their corresponding linear compounds. The performances of the compounds were compared to that of lipid-based saturated and unsaturated acids, esters and alcohols as well as to that of commercial synthetic lubricant formulations. At low concentrations ($0.5%) in paraffin oil and for the load conditions used, the branched compounds showed minor differences in friction behavior as compared to their linear counterparts. The ester compounds by comparison showed higher friction behavior than alcohols and acids.

Bookmarks Related papers MentionsView impact

In this study, the tribological properties of tung oil-based polymers synthesized by the cationic... more In this study, the tribological properties of tung oil-based polymers synthesized by the cationic copolymerization of tung oil with divinylbenzene and styrene are evaluated as a function of crosslinking density. Tribological measurements were performed using a ball-on-flat reciprocating microtribometer on samples with three crosslinking densities of 20%, 30% and 40% by weight of the crosslinking agent. Friction and wear characteristics during dry sliding were evaluated using a spherical (1.2 mm radius) silicon nitride probe as well as a conical (100 mm radius, 901 cone angle) diamond probe. Microscale friction behavior was evaluated from single strokes at ramped normal loads, whereas wear experiments were evaluated from 100 to 500 reciprocating cycles at fixed normal loads. Elastic modulus and hardness information were evaluated using nanoindentation tests. Scanning electron microscopy of wear tracks was used to elucidate deformation mechanisms in the various samples. All samples showed friction coefficients ranging from 0.06 to 0.49. It was found that a higher crosslinking density resulted in lower abrasive wear due to increased hardness. These results provide some insight into the friction and wear behavior of tung oil-based polymers.

Bookmarks Related papers MentionsView impact

Thermosetting composites have been prepared by the use of a biobased resin and spent germ filler,... more Thermosetting composites have been prepared by the use of a biobased resin and spent germ filler, which is a byproduct from a wet ethanol production plant. Microscale tribological measurements were performed on samples with different concentrations of the filler as well as the crosslinker using a ball-on-flat reciprocating microtribometer. Microscale friction and wear behavior during dry sliding were evaluated using a spherical silicon nitride probe (radius 1.2 mm) and a conical diamond (radius 100 mm, cone angle 901) probe to impose different contact conditions. Finally, a pin-on-disc tribometer was used to study the macroscale wear properties at high loads against an alumina pin. Scanning electron microscopy (SEM) images of wear tracks on the samples were obtained to elucidate deformation mechanisms. All samples showed evidence of abrasive wear in both micro-and macro-scales. It was found that an increase in the concentration of the filler resulted in higher friction coefficients against Si 3 N 4 , while an increase in the concentration of the crosslinker lowered the abrasive wear depth. These results provide some insight into the effectiveness of using biobased spent germ–tung oil polymer composites as potential tribomaterials.

Bookmarks Related papers MentionsView impact

Nanoindentation-induced phase transformations in both crystalline silicon (c-Si) (100) and ion-im... more Nanoindentation-induced phase transformations in both crystalline silicon (c-Si) (100) and ion-implanted amorphous silicon have been studied at temperatures up to 200 °C. The region under the indenter undergoes rapid volume expansion at temperatures above 125 °C during unloading, which is indicated by " bowing " behavior in the load–displacement curve. Polycrystalline Si-I is the predominant end phase for indentation in crystalline silicon whereas high-pressure Si-III/Si-XII phases are the result of indentation in amorphous silicon. We suggest that the Si-II phase is unstable in a c-Si matrix at elevated temperatures and can directly transform to Si-I during the early stages of unloading.

Bookmarks Related papers MentionsView impact

Macromolecular Materials and Engineering, 2011

Bookmarks Related papers MentionsView impact

Journal of the American Oil Chemists' Society, 2010

Bookmarks Related papers MentionsView impact

The motion of the triple line during the debonding of a soft viscoelastic adhesive from a rigid p... more The motion of the triple line during the debonding of a soft viscoelastic adhesive from a rigid polymer surface has been investigated quantitatively. In order to make the debonding geometry simpler than the probe tack test, a new technique, called the sticky wedge test, has been developed where the probe is constituted by a horizontal cylinder instead of a flat punch. The crack propagates in the elongated contact area between the cylinder and the flat surface, thereby, allowing us to measure optically in situ the crack-tip velocity and the receding contact angle of the debonding adhesive. Two model pressure sensitive adhesives (PSA) based on poly(n-butyl acrylate-co-acrylic acid) with different molecular weights and branching levels and four polymer substrates (rubbery or glassy at room temperature) were used. Due to the soft and incompressible nature of the adhesive, the strain energy release rate for this test geometry has been estimated by the equations for the pure shear test geometry. The results show three main new insights: first, despite significant approximations, this novel approach holds promise to characterize more quantitatively the interfacial crack propagation between soft viscoelastic solids and hard surfaces and the relationship between the applied energy release rate G and the crack-tip velocity v has been reliably established for eight combinations of the model viscoelastic adhesives and surfaces. Second, at equivalent values of the thermodynamic work of adhesion, the adhesion energy of both the adhesives against the rubbery surface was much lower than that against the glassy polymers. Third, surprisingly, the measured receding contact angle of debonding was close to 90 for all adhesive/ surface combinations used.

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