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1

Optimization of Process Parameters of Ultrasonic Welding on Dissimilar Metal Joints

Mohan Kumar Anand, Rajasekar R., Karthik Vaduganathan, Kheawhom Soorathep

Archives of Metallurgy and Materials

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2021

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Vol. 66, iss. 3

887--892

EN

Nowadays the automotive industry mostly prefers innovative solid-state welding technologies that would enable to welding of lightweight and high-performance materials. In this work, 3105-H18 Aluminium alloy (Al) and pure Copper (Cu) specimens with 0.5 mm thickness have been ultrasonically welded in a dissimilar (Al-Cu) manner. Optimization of process parameters of ultra-sonic welding has been carried out through full factorial method, three levels of variables considered for this experimental studies namely, weld pressure, amplitude, and time, also each variable interaction with welding strength has been studied. Additionally, micro-hardness and microstructure investigation in welded joints has been studied. The result shows that the weld strength greatly influenced weld amplitude at a medium and higher level of weld pressure. The interface micro-hardness of the welded joint has lower compared to the base metal.

2

Development of calcium titanium oxide coated silicon solar cells for enhanced voltage generation capacity

Kathirvel K., Rajasekar R., Shanmuharajan T., Pal S. K., Kumar P. S., Kumar J. S.

Materials Science Poland

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2017

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Vol. 35, No. 1

181--187

EN

Depletion of fossil fuel based energy sources drive the present scenario towards development of solar based alternative energy. Polycrystalline silicon solar cells are preferred due to low cost and abundant availability. However, the power conversion efficiency of polycrystalline silicon is lesser compared to monocrystalline one. The present study aims at analyzing the effect of calcium titanium oxide (CaTiO3) antireflection (AR) coating on the power conversion of polycrystalline solar cells. CaTiO3 offers unique characteristics, such as non-radioactive and non-magnetic orthorhombic biaxial structure with bulk density of 3.91 g/cm3. CaTiO3 film deposition on the solar cell substrate has been carried out using Radio Frequency (RF) magnetron sputter coating technique under varying time durations (10 min to 45 min). Morphological studies proved the formation of CaTiO3 layer and respective elemental percentages on the coated substrate. Open circuit voltage studies were conducted on bare and coated silicon solar substrates under open and controlled atmospheric conditions. CaTiO3 coated on a solar cell substrate in a deposition time of 30 min showed 8.76 % improvement in the cell voltage compared to the bare solar cell.

3

Review on Parameters Influencing the Rice Breakage and Rubber Roll Wear in Sheller

Prabhakaran P., Ranganathan R., Muthu Kumar V., Rajasekar R., Devakumar L., Pal S. K.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 3

1875--1880

EN

The present review deals with parameters influencing the rice breakage during rice milling operations and the effect of rubber roll Sheller in rice husk removal process. The main objective of rice milling system is to remove the husk and bran layer to produce the white rice. In this process, rubber roll sheller is used to remove husk from the grains by friction process. If the rubber material is too soft, there may not be sufficient shear force to husk the paddy. Wear will be minimum for rubber material with high hardness but indeed it pronounce the breakage of rice. Hence, for efficient husking the rubber roll material should possess the balance of physico-mechanical properties. Rice breakage depends on several other parameters like the type of harvest, drying temperature, drying methods, physical characteristics of paddy, husking characteristics, paddy moisture content, rubber roller speed, rubber roll pressure, paddy feed rate and fissures. Rubber roll wear depends on the type of rubber material attached to the roller, feed rate, roller speed, pressure etc.

4

Influence of Rock Properties on Wear of M and SR Grade Rubber with Varying Normal Load and Sliding Speed

Pal S. K., Rao K. U. M., Kumar P. S., Rajasekar R.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 3

1787--1793

EN

Rubbers are interesting materials and are extensively used in many mining industries for material transportation. Wear of rubber is a very complex phenomenon to understand. The present study aims to explain the influence of rock properties on wear of M and SR grade rubber used in top cover of conveyor belts. Extensive laboratory experiments were conducted under four combinations of normal load and sliding speed. The wear of both the rubber types were analyzed based on the rock properties like shear strength, abrasivity index and fractal dimension. A fully instrumented testing set up was used to study the wear of rubber samples under different operating conditions. In general, wear was higher for M grade rubber compared to SR grade rubber. Increase in shear strength of rocks depicts decreasing trend for the wear of M and SR grade rubber at lower load conditions. Moreover, a higher load combination displays no definite trend in both the rubbers. The strong correlation between the wear of rubber and frictional power for all rubber-rock combinations has given rise to the parameter A, which reflects the relative compatibility between the rubber and rock. Increase of Cerchar’s Abrasivity Index of rocks shows gradual enhancement in wear for M grade rubber in all the load and speed combinations whereas, it fails in SR grade rubber due to its higher strength. The wear of rubber tends to decrease marginally with the surface roughness of rocks at highest normal load and sliding speed in M grade rubber. However, the wear of M and SR grade rubber is influenced by the surface roughness of rocks.

5

Influence of Cutting Fluid Flow Rate and Cutting Parameters on the Surface Roughness and Flank Wear of TiAlN Coated Tool in Turning AISI 1015 Steel Using Taguchi Method

Moganapriya C., Rajasekar R., Ponappa K., Venkatesh R., Karthick R.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 3

1827--1832

EN

This paper presents the influence of cutting parameters (Depth of cut, feed rate, spindle speed and cutting fluid flow rate) on the surface roughness and flank wear of physical vapor deposition (PVD) Cathodic arc evaporation coated TiAlN tungsten carbide cutting tool insert during CNC turning of AISI 1015 mild steel. Analysis of Variance has been applied to determine the critical influence of cutting parameters. Taguchi orthogonal test design has been employed to optimize the process parameters affecting surface roughness and tool wear. Depth of cut was found to be the most dominant factor contributing to high surface roughness (67.5%) of the inserts. However, cutting speed, feed rate and flow rate of cutting fluid showed minimal contribution to surface roughness. On the other hand, cutting speed (45.6%) and flow rate of cutting fluid (23%) were the dominant factors influencing tool wear. The optimum cutting conditions for desired surface roughness constitutes the following parameters such as medium cutting speed, low feed rate, low depth of cut and high cutting fluid flow rate. Minimal tool wear was achieved for the following process parameters such as low cutting speed, low feed rate, medium depth of cut and high cutting fluid flow rate.

6

Experimental Analysis of Nitrogen as an Alloying Element in WC9 Grade Steel

Vishnuh V., Sudhakar S., Tamilarasu K., Prabhakaran P., Rajasekar R.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 3

1889--1894

EN

In the present work the effect of nitrogen on WC9 alloy at various weight percentages was analyzed and tested for their microstructural and mechanical properties. The nitrogen was added at 0.05, 0.10, 0.15, 0.20 and 0.25 wt. % in the solid form as nitrided ferrochrome to WC9 alloy. The samples were heat treated by solution annealing process at a temperature of 1100°C for 5 hours to improve the austenitic formation. Microstructures and mechanical properties such as tensile strength, yield strength, hardness, % elongation and % reduction of WC9-N alloy were examined. It was observed that increasing nitrogen wt. % increases the mechanical properties. The obtained mechanical properties were compared with base WC9 and C12A grade steel, where it was found to be replacement for C12A grade steel at its composition at lower end. The material cost analysis for WC9-N and C12A grade steel was done and both were compared.

7

Effect of Ovality in Inlet Pigtail Pipe Bends Under Combined Internal Pressure and in-Plane Bending for Ni-Fe-Cr B407 Material

Ramaswami P., Senthil Velmurugan P., Rajasekar R.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 3

1881--1887

EN

The present paper makes an attempt to depict the effect of ovality in the inlet pigtail pipe bend of a reformer under combined internal pressure and in-plane bending. Finite element analysis (FEA) and experiments have been used. An incoloy Ni-Fe-Cr B407 alloy material was considered for study and assumed to be elastic-perfectly plastic in behavior. The design of pipe bend is based on ASME B31.3 standard and during manufacturing process, it is challenging to avoid thickening on the inner radius and thinning on the outer radius of pipe bend. This geometrical shape imperfection is known as ovality and its effect needs investigation which is considered for the study. The finite element analysis (ANSYS-workbench) results showed that ovality affects the load carrying capacity of the pipe bend and it was varying with bend factor (h). By data fitting of finite element results, an empirical formula for the limit load of inlet pigtail pipe bend with ovality has been proposed, which is validated by experiments.

8

Development of compatibilized butyl rubber nanocompo-sites containing dual filler system

Rajasekar R., Malas A., Das C.K.

Elastomery

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2012

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T. 16, nr 4

22-28

EN

This study aims in analyzing the effect of compatibilizer for the dispersion of organically modified nanoclay in butyl rubber (IIR) matrix. Chlorobutyl rubber (CIIR) - organically modified nanoclay com-posites (CI-C) were prepared by solution mixing. The nanoclay used in this study is Cloisite 20A. The ob-tained nanocomposites were incorporated in butyl rubber (IIR) along with carbon black with sulphur as a curing agent. Morphology, curing characteristics, mechanical and gaś barrier properties ofthe nanocomposites were analysed and compared to control. The morphological studies proved the partial exfo-liation along with agglomeration of nanoclay platelets in CIIR, andfurther incorporation ofCI-C in IIR matrix enhances the exfoliation ofthe nanoclay platelets. Curing study demonstrated faster scorch time, cure time and increase in maximum torąuefor the compatibilized IIR nanocomposites containing dual filler system compared to control. Tremendous improvement in mechanical and gaś barrier properties were achieved for the same system. The tensile fractured surface of the rubber compounds observed through scanning electron microscopy shows highly rough and tortuous path for the filler containing IIR compounds.

PL

Przedstawiona praca jest ukierunkowana na przeanalizowanie wpływu środka kompatybilizującego na dyspergowanie organicznie modyfikowanego nanoglinokrzemianu w środowisku kauczuku butylowego (IIR). Kompozyty użytego jako kompatybilizatora kauczuku chlorobutylowego (CIIR) i organicznie modyfikowanego nanoglinokrzemianu (Cl-C) przygotowywano przez zmieszanie skladników w roztworze. Jako nanoglinokrzemianu użyto w badaniach Cloisite 20A. Uzyskane nanokompozyty wprowadzano do kauczuku butylowego (IIR) razem z sadzą i siarką jako środkiem sieciującym. Właściwości nanokompozytów - morfologiczne, wulkanizacyjne, mechaniczne i barierowe wobec gazu - analizowano i porównywano z próbką kontrolną. Badania morfologii wykazały częściową eksfoliację z jednoczesną aglomeracją płytek nanoglinokrzemianu w CIIR, a następnie wprowadzanie Cl-C do matrycy IIR zwiększało eksfoliację płytek nanoglinokrzemianu. Badania wulkanizacji wykazały krótszy czas podwulkanizacji i wulkanizacji oraz wzrost maksymalnego momentu obrotowego kompatybilizowanych nanokompozytów IIR zawierających dwuskładnikowy zespół napełniaczy w porównaniu z próbką kontrolną. Stosując opisany system uzyskano ogromną poprawę właściwości mechanicznych i barierowych produktu. Powierzchnia przełomu po rozciąganiu obserwowana pod mikroskopem elektronowym okazała się bardziej szorstka i nierówna w przypadku napełnionych mieszanek IIR.

9

Effect of dual fillers on the properties of acrylonitrile butadiene rubber nanocomposites in presence of compatibilizer

Rajasekar R., Nayak G.C., Malas A., Sahoo S., Das C.K.

Elastomery

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2011

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T. 15, nr 3

3-13

EN

Acrylonitrile butadiene rubber (NBR) nanocomposites containing nanoclay and carbon black were prepared in presence of compatibilizer. The nanoclay used in this study is Cloisite 20A and the compatibilizer used for dispersing nanoclay in NBR is epoxidized natural rubber (ENR). The preparation of NBR nanocomposites involves two step processes. Initially nanoclay was incorporated in ENR by solution mixing. The minimum loading of the obtained ENR-nanoclay composites (EC) were incorporated in NBR followed by the addition of carbon black. The changes obtained in the morphological, mechanical, swelling and compression set properties upon minimum loading of nanoclay in the carbon black filled NBR compounds were analysed and compared with gum and carbon black filled NBR systems. The morphological studies proved the intercalation of nanoclay in ENR. Incorporation of EC in NBR in presence of carbon black leads to partial exfoliation of nanoclay platelets in the NBR matrix. Curing studies depicted faster scorch time, cure time and increase in torque for the dual filler containing NBR compounds. Dynamic mechanical thermal analysis (DMTA) showed increase in storage modulus and lesser damping characteristics for the dual filler containing NBR compounds accompanied with significant improvement in mechanical, resistance to swelling and low compression set properties.

PL

Nanokompozyty kauczuku butadienowo-akrylonitrylowgo (NBR) zawierające nanoglinokrzemian (Cloisite 20A) i sadzę przygotowano w obecności kompatybilizatora. Jako kompatybilizatora ułatwiającego dyspergowanie nanokrzemianu w NBR użyto epoksydowanego kauczuku naturalnego (ENR). Proces przygotowania nanokompozytów NBR przebiegał dwuetapowo. Najpierw wprowadzano nanokrzemian do ENR przez mieszanie w roztworze. Niewielką ilość uzyskanych kompozytów ENR-nanokrzemian (EC) wprowadzono do NBR, a następnie dodawano sadzę. Przeanalizowano właściwości morfologiczne i mechaniczne oraz pęcznienie i odkształcenie trwałe tak zmodyfikowanych mieszanek. Uzyskane wyniki porównano z właściwościami mieszanek NBR napełnionych tylko sadzą oraz niezawierających napełniaczy. Badania morfologiczne potwierdziły interkalację nanokrzemianu w ENR Stwierdzono, że dodanie EC do NBR w obecności sadzy prowadzi do częściowej eksfoliacji płytek nanoglinokrzemianu w matrycy NBR. Mieszanki NBR zawierające obydwa napełniacze odznaczały się krótszym czasem podwulkanizacji, wulkanizacji i wzrostem momentu obrotowego. Analiza termiczna dynamiczno-mechaniczna (DMTA) wykazała wzrost składowej rzeczywistej modułu zespolonego i gorsze właściwości tłumiące mieszanek NBR zawierających dwuskładnikowy zespół napełniaczy, czemu towarzyszyła znacząca poprawa właściwości mechanicznych, odporności na pęcznienie oraz małe odkształcenie trwałe.

10

Development of compatibilized butyl rubber nanocomposites containing dual filler system

Rajasekar R., Malas A., Das C.K.

Elastomery

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2010

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T. 14, nr 6

15-22

EN

This study aims in analyzing the effect of compatibilizer for the dispersion of organically modified nanoclay in butyl rubber (IIR) matrix. Chlorobutyl rubber (CIIR) - organically modified nanoclay composites (CI-C) were prepared by solution mixing. The nanoclay used in this study is Cloisite 20A. The obtained nanocomposites were incorporated in butyl rubber (IIR) along with carbon black and sulphur as a curing agent. Morphology, curing characteristics, mechanical and gas barrier properties of the nanocomposites were analysed and compared to control. The morphological studies proved the partial exfoliation along with agglomeration of nanoclay platelets in CIIR, and further incorporation of CI-C in IIR matrix enhances the exfoliation of the nanoclay platelets. Curing study demonstrated faster scorch time, cure time and increase in maximum torque for the compatibilized IIR nanocomposites containing dual filler system compared to control. Considerables improvement in mechanical and gas barrier properties were achieved for the same system. The tensile fractured surface of the rubber compounds observed through scanning electron microscopy shows highly rough and tortuous path for the filler containing IIR compounds.

PL

Praca ma na celu analizę wpływu kompatybilizatora na dyspersję organicznie modyfikowanego nanoglinokrzemianu w matrycy kauczuku butylowego. Kompozyty kauczuku chlorobutylowego i modyfikowanego nanoglinokrzemianu wykonywano metodą mieszania w roztworze. Do badań użyto nanoglinokrzemianu Cloisite 20A. Uzyskane nanokompozyty wprowadzano do kauczuku butylowego (IIR) razem z sadzą i siarką jako środkiem wulkanizującym. Badano morfologię, charakterystykę wulkanizacji, właściwości mechaniczne i przepuszczalność gazu nanokompozytów, porównując uzyskane wyniki z właściwościami próbki kontrolnej. Badania morfologiczne dowiodły częściowej eksfoliacji oraz aglomeracji płytek nanoglinokrzemianu w CIIR, a następnie, że dodanie CI-C do matrycy IIR poprawia eksfoliację płytek nanoglinokrzemianu. Badanie wulkanizacji wykazało krótszy czas podwulkanizacji i wulkanizacji oraz wzrost maksymalnego momentu obrotowego kompozytów kompatybilizowanego IIR zawierającego zespół dwóch napełniaczy w porównaniu z próbką kontrolną. Osiągnięto znaczną poprawę właściwości mechanicznych i barierowych. Obserwacja za pomocą skaningowego mikroskopu elektronowego powierzchni mieszanki gumowej ze spękaniami powstałymi na skutek naprężenia pokazuje bardzo ostrą i zmiennokierunkową drogę spękań w przypadku napełnionych mieszanek IIR.

11

Elastomeric nanocomposites based on EPR and oil extended EPDM

Rajasekar R., Das C.K.

Elastomery

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2009

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T. 13, nr 5

3-11

EN

The crucial factor that decides the improvement of properties in rubber by the incorporation nanofiller, is its distribution in the rubber matrix. The normal mixing of non polar rubber and organically modified nanoclay may not lead for the exfoliation of the filler in the rubbery matrix. Hence, some sort of polar rubber like epoxidized natural rubber (ENR) can be used as a compatibilizer, inorder to obtain a better dispersion of the nanoclay in the matrix polymer. Epoxidized natural rubber and organically modified nanoclay composites (EC) were prepared by solution mixing. The nanoclay used in this study is Cloisite 20A. The obtained nanocomposites were incorporated in the oil-extended ethylene propylene diene monomer (OE-EPDM) with sulphur as a curing agent and also in ethylene propylene rubber (EPR) containing dicumyl peroxide curing system. The morphological studies proved the intercalation of nanoclay in ENR and further incorporation of EC in OE-EPDM and EPR matrix leads to exfoliation of the nanoclay. Curing study demonstrated faster scorch time, cure time and increase in maximum torque for the nanoclay incorporated OE-EPDM and EPR compounds compared to their controls. Dynamic mechanical thermal analysis showed increase in storage modulus and lesser damping characteristics for the compounds containing nanoclay loading in OE-EPDM and EPR matrices, accompanied by improvements in other technical properties.

PL

Czynnikiem decydującym o poprawie właściwości gumy przez dodatek nanonapełniacza jest jego zdyspergowanie w ośrodku kauczukowym. Zwykłe mieszanie niepolarnego kauczuku i nanoglinokrzemianu modyfikowanego substancją organiczną może nie doprowadzić do eksfoliacji napełniacza w matrycy kauczukowej. Dlatego, w celu uzyskania jego lepszej dyspersji w kauczuku, można zastosować jako kompatybilizator polarny, epoksydowany kauczuk naturalny (ENR). Kompozyty (EC) epoksydowanego kauczuku naturalnego i organicznie modyfikowanego nanoglinokrzmianu (Cloisite 20A) przygotowywano przez mieszanie w roztworze. Uzyskane nanokompozyty wprowadzano do EPDM modyfikowanego olejem (OE-EPDM), z siarką jako środkiem wulkanizującym oraz do kauczuku elylenowo-propylenowego (EPR) zawierającego zespół wulkanizujący z nadtlenkiem dikumylu. Badania morfologiczne potwierdziły interkalację nanoglinokrzemianu w ENR, a nastepnie jego eksfoliację po wprowadzeniu EC do OE-EPDM lub EPR. W badaniu procesu wulkanizacji stwierdzono szybszą podwulkanizację i krótszy czas wulkanizacji oraz wzrost maksymalnego momentu reometrycznego mieszanek OE-EPDM i EPR zawierających dodatek nanoglinokrzemianu w stosunku do mieszanek kontrolnych. Badania DMTA wykazaly wzrost składowej rzeczywistej modułu zespolonego oraz słabsze właściwości tłumiące mieszanek OE-EPDM i EPR zawierających EC, towarzyszyła temu poprawa innych wlaściwości technicznych.