Browsing by Author "Surendranathan, A.O."

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Assessment of corrosion behavior of ductile irons by factorial experiments
(2009) Surendranathan, A.O.; Prabhu, K.N.; Sudhaker Nayak, H.V.
The corrosion behavior of unalloyed and alloyed ductile irons (as cast, annealed, and cold worked) in sea water, dilute sulfuric acid, and dilute sodium hydroxide solutions was assessed. Specimen history had a significant effect on the corrosion potential except in ductile iron alloyed with Ni. When the specimens were subjected to different levels of cold working, the corrosion rate was influenced by both the history and the medium. Temperature had a significant effect on the corrosion rate except in the case of unalloyed ductile iron. Factorial experiments indicated that the cold-worked samples were more sensitive to the effect of temperature and composition on the corrosion rate as compared to annealed and as-cast samples. The medium had a significant effect on the corrosion rate in all the cases. © 2009 ASM International.
Carbon-carbon composites by preformed yarn method
(2011) Naik, P.; Neelakantha, N.V.; Surendranathan, A.O.; Jayaraju, T.
The conventional techniques of manufacturing carbon-carbon(C/C) composites have reportedly encountered problems because the resulting C/C composites exhibit non-uniform properties such as bending strength and density. A novel method of manufacturing C/C composites by preformed yarns (PY) is used. The matrix powder consists of coke powders and the binder. The preformed yarn contains the matrix powders inside the carbon fiber bundle and coated on circumference with nylon-6 polymer. This preformed yarn is then chopped and hot pressed at about 600°C to get bars and pellets. These are again heat treated at 1500°C and further impregnated by one more pitch cycle, again heat treated at 2200°C. The tests for hardness, compression strength, Creep strength, resistance to oxidation, and fracture toughness are conducted on these pellets and bars. The micostructural analysis in SEM is done. These tests reveal that the properties obtained from PY method are superior to the properties obtained from any other conventional method.
Composites with graphene as reinforcement
(2019) Surendranathan, A.O.
In this paper, the developments in the area of graphene-reinforced composite have been reviewed. It also depicts the work guided by the author. In the work, WC powder with 6% cobalt (Co) and graphene (0.2%) in the form of graphene nanoplatelets (GPLs) was prepared by high energy rate ball milling and ultrasonification. The mixture was sintered using spark plasma sintering at 1250�C for 10 min. To study the effects of graphene reinforcement, the sample was analyzed for the physical (density), magnetic (coercivity, and magnetic saturation), microstructural (porosity) and mechanical properties (hardness, fracture toughness). Under Visual Inspection of the Spark Plasma Sintered (SPS) sample, the top surface showed more homogeneous distribution of the constituents than the bottom surface. The results of the surface measurements showed that the top and bottom surfaces have almost the same roughness. It was found that the SPS sample exceeded liquid phase sintered (LPS) specimens with respect to hardness and fracture toughness values. The coercive force was found to be higher for the LPS sample whereas the saturation magnetization value was found to be higher for the SPS sintered specimen. The density value is higher for the LPS sintered specimen. The presence of pores is seen in the back scattered electron (BSE) image. There was certain amount carbon pick up from the graphite die used in SPS. There was uniform distribution of the cobalt binder. The x-ray diffraction pattern for the SPS sintered sample indicates the presence of WC, Co and GNP. � 2019 IOP Publishing Ltd. All rights reserved.
Composites with graphene as reinforcement
(Institute of Physics Publishing helen.craven@iop.org, 2019) Surendranathan, A.O.
In this paper, the developments in the area of graphene-reinforced composite have been reviewed. It also depicts the work guided by the author. In the work, WC powder with 6% cobalt (Co) and graphene (0.2%) in the form of graphene nanoplatelets (GPLs) was prepared by high energy rate ball milling and ultrasonification. The mixture was sintered using spark plasma sintering at 1250Â°C for 10 min. To study the effects of graphene reinforcement, the sample was analyzed for the physical (density), magnetic (coercivity, and magnetic saturation), microstructural (porosity) and mechanical properties (hardness, fracture toughness). Under Visual Inspection of the Spark Plasma Sintered (SPS) sample, the top surface showed more homogeneous distribution of the constituents than the bottom surface. The results of the surface measurements showed that the top and bottom surfaces have almost the same roughness. It was found that the SPS sample exceeded liquid phase sintered (LPS) specimens with respect to hardness and fracture toughness values. The coercive force was found to be higher for the LPS sample whereas the saturation magnetization value was found to be higher for the SPS sintered specimen. The density value is higher for the LPS sintered specimen. The presence of pores is seen in the back scattered electron (BSE) image. There was certain amount carbon pick up from the graphite die used in SPS. There was uniform distribution of the cobalt binder. The x-ray diffraction pattern for the SPS sintered sample indicates the presence of WC, Co and GNP. Â© 2019 IOP Publishing Ltd. All rights reserved.
Corrosion behavior of high and low temperature austempered ductile iron (ADI) in iron ore slurry
(ASTM International, 2017) Aithal, P.M.; Vijayan, V.; Surendranathan, A.O.; Udupa, K.R.; Samuel, K.G.
Corrosion behavior of austempered ductile iron (ADI) and forged EN31 steel balls in a ground iron ore slurry was studied as a function of time in the slurry, while the microstructure of ADI developed due to different tempering temperature and tempering time. The corrosion rates of the grinding balls immersed in the iron ore slurry were determined using electrochemical analysis and weight loss methods. It was found that the pH of the iron ore slurry increased with time and the corrosion behavior was influenced by the pH of the slurry. The corrosion rate of forged EN31 steel balls increased with the increase in time and pH of the slurry, whereas the corrosion rate of ADI balls depended on the austempering treatment. In general, the forged EN31 steel ball offered better corrosion resistance than ADIs during the early stages of exposure in the slurry (low pH values of the slurry), but at higher pH values of the slurry, the ADIs yielded better corrosion resistance than forged EN31 steel balls. The ADI austempered at higher temperatures showed better corrosion resistance than the ones austempered at lower temperatures. © © 2017 by ASTM International.
Corrosion mitigation of the oil well steels using organic inhibitors-A review
(2012) Puthalath, P.; Surendranathan, A.O.; Murthy, C.S.N.
Oil well stimulation, usually done with hot solutions of hydrochloric acid, may induce severe corrosion attack on production tubing, downhole tools and casing. Inorganic, organic and combinations of acids along with surfactants are used in a variety of well stimulation treatments. To reduce the aggressive attack of the acid on tubing and casing materials (N80 steel), inhibitors are added to the acid solution during the acidifying process. The inhibition in oil and gas field is more complicated and requires special eco-friendly inhibitors depending on the area of application such as in refineries, wells, recovery units, pipelines etc. Aggressive gases such as H2S, CO2, and organic acids complicate the problem of inhibition in wells. Various factors have to be considered while dealing with corrosion problems of oil and gas industry. The type of reservoir rocks, the acids used for stimulation, the oil well equipments such as tubings and casings and the operating conditions are some of the important factors that affect the corrosivity. Each and every case has to be considered in its totality before a decision is made on the proper materials. No particular material is the cure for all the evils of corrosion. It is imperative to the field operators, pipeline engineers, designers to have corrosion awareness concerning the oil and gas industries in their day to day activities to compact and mitigate corrosion. This work is an attempt in this direction.
Defence applications of polymer nanocomposites
(2010) Kurahatti R.V.; Surendranathan, A.O.; Kori S.A.; Singh N.; Kumar A.V.R.; Srivastava S.
The potential opportunities promised by nanotechnology for enabling advances in defence technologies are staggering. Although these opportunities are likely to be realised over a few decades, many advantages are currently being explored, particularly for defence applications. This review provides an insight into the capabilities offered by nanocomposites which include smart materials, harder/lighter platforms, new fuel sources and storage as well as novel medical applications. It discusses polymer-based nanocomposite materials, nanoscale fillers and provides examples of the actual and potential uses of nanocomposite materials in defence with practical examples. © 2010, DESIDOC.
Defence applications of polymer nanocomposites
(Defense Scientific Information and Documentation Centre, 2010) Kurahatti, R.V.; Surendranathan, A.O.; Kori, S.A.; Singh, N.; Kumar, A.V.R.; Srivastava, S.
The potential opportunities promised by nanotechnology for enabling advances in defence technologies are staggering. Although these opportunities are likely to be realised over a few decades, many advantages are currently being explored, particularly for defence applications. This review provides an insight into the capabilities offered by nanocomposites which include smart materials, harder/lighter platforms, new fuel sources and storage as well as novel medical applications. It discusses polymer-based nanocomposite materials, nanoscale fillers and provides examples of the actual and potential uses of nanocomposite materials in defence with practical examples. © 2010, DESIDOC.
Effect of milling time on production of aluminium nanoparticle by high energy ball milling
(IAEME Publication, 2018) Rijesh, M.; Sreekanth, M.S.; Deepak, A.; Dev, K.; Surendranathan, A.O.
High-energy ball milling is a promising and effective technique for the production of aluminium nanoparticles. Elemental aluminium powder of 325 mesh, 99.5% purity is taken for this investigation. A planetary ball mill, PM 100, with tungsten carbide balls of diameter 9.5 mm was used. The vial containing 62 g of powder and 620 g of tungsten carbide balls in the ratio 1:10 (wt/wt) was utilized. Toluene was used as a wet grinding media in order to reduce the heat produced during ball milling operation. Ball milling was carried out for 70 hours and the obtained nano-particles were characterized using wide angle X-Ray diffraction technique. The peaks were analyzed by using PANalytic X'pert HighScore software. Optimum milling time for producing nanoparticles of size 20-21 nm was found to be 50-60 hours. © 2018 IAEME Publication.
Effect of plastic strain and processing routes on the hardness of as-cast aluminum
(American Institute of Physics Inc. subs@aip.org, 2020) Valder, J.; Rijesh, R.; Kumar, P.; Saminathan, S.; Raju, K.; Surendranathan, A.O.
In the present study, Equal Channel Angular Pressing (ECAP) of commercially pure aluminum (Al) in the cast form was carried out at room temperature for assessing its hardness by different routes and passes. The different routes employed in the present investigation are A, BA, BC and C. The Al specimens were pressed by a die of 150Â° channel angle without back pressure with Molybdenum disulfide (MoS2) as the lubricant. ECAP has significantly improved the hardness of Al in the subsequent passes. It has been observed that the hardness has been increased after first pass at room temperature from 47 VHN in the annealed condition to 54 VHN and after the second pass the hardness value has been increased to 56, 57, 62 and 56 VHN for routes A, BA, BC and C respectively. The increase in the hardness may be attributed to the severe fragmentation of microstructure of cast Al and the change in the orientation of the specimen from one pass to the next pass. After one pass, the dendritic microstructure of cast Al has been distorted by the shear stress developed during deformation. The processing by different routeswith number of passes has further refined the microstructure leading to a better hardness in the cast Al. Â© 2020 Author(s).
Experimental investigation on corrosion control of 13CR L80 steel in hydrochloric acid solution using thiophene methanol
(2014) Puthalath, P.; Surendranathan, A.O.; Murthy, Ch.S.N.; John Berchmans, L.
The influence of different eco-friendly inhibitors on the corrosion behavior of 13Cr L80 steel in 15% HCl solution was experimentally investigated. In the preliminary study, corrosion tests were performed with various oil well steels like13Cr L80, L80, N80 and P110 steels in order to evaluate the comparative corrosion resistance of these metals when exposed to 15% aqueous hydrochloric acid solutions without inhibitors. In this paper the inhibitive action of a selected inhibitor, thiophene methanol (TML) on the corrosion behaviour of 13Cr L80 steel in 15% HCl solution at different levels of concentrations (0-100 mM) was investigated using weight-loss, electrochemical polarization and AC impedance spectroscopic methods and their results were compared. The inhibition efficiency of TML increased almost linearly with its concentration and was found to be maximum (86.79%) at 75 mM and the increase in temperature resulted in the decrease of the inhibitor efficiency (?) and degree of surface coverage (?). Surface morphology of the corroded sample was analyzed by SEM. FT-IR spectral study and TGA were carried out to characterize the surface products. The result shows that TML is a good inhibitor for 13Cr L80 steel in HCl acid medium. The adsorption of the TML on the 13Cr L80 steel surface obeyed the Langmuir adsorption isotherm. Thermodynamic and activation parameters are discussed.
Experimental investigation on Mode-I fracture toughness of Carbon-Carbon composites fabricated by preformed yarn method
(Elsevier Ltd, 2021) Sunil Kumar, B.V.S.; Neelakantha Londe, V.; Lokesha, M.; Anilas, M.; Surendranathan, A.O.
Carbon-Carbon composites are one such material that gives designers significant importance for advanced applications over conventional materials. They are applied in applications at very high temperatures (up to 3000Â°C), and under extreme conditions. They have a density which is much less than metals and ceramics and thus, make low part weight a significant factor for aerospace applications. Fracturing toughness is a measurable way to express a substance's resistance to fracture in the case of a break. This paper describes the experimental studies done to investigate the Mode-1 fracture toughness of carbon-carbon composites which was fabricated via the preformed yarn method. Fracture toughness was determined for four different (a/w) ratios i.e. 0.45, 0.47, 0.50 and 0.52 respectively. The results showed that with only two cycles of pitch impregnation, HIP and graphitizing, carbon-carbon composites were successfully produced. The specimen having an (a/w) ratio of 0.45 had a higher fracture toughness value in comparison with all values. As the (a/w) ratio was increasing, the fracture toughness value decreased and the fractured surface clearly shows a brittle fracture behavior. Â© 2021 Elsevier Ltd. All rights reserved.
Failure Analysis of Cast Tubular Specimens of Al–5Zn–1Mg While Processing at Room Temperature by Equal Channel Angular Pressing (ECAP)
(Springer Science and Business Media, LLC, 2014) Valder, J.; Rijesh, M.; Surendranathan, A.O.
The ECAP process is a promising technique for imparting large plastic deformation and breaking down the ingot cast structure without a resultant decrease in cross-sectional area. In the present study, the suitability of this technique for processing cast Al–5Zn–1Mg tubular specimens at room temperature has been investigated. Tubular specimens were extruded through an ECAP die with an angle of 150° between the two intersecting channels without a back pressure. Sand was used as a mandrel during pressing. The tubular specimens failed miserably in the first pass itself. A failure analysis was carried out using SEM, and cause for failure was determined. © 2014, ASM International.
Forming of tubular commercial purity aluminum by ECAP
(2012) Valder, J.; Rijesh, M.; Surendranathan, A.O.
The equal channel angular pressing (ECAP) process is a promising technique for imparting a large plastic deformation to materials without a resultant decrease in cross-sectional area. In the present study, the suitability of this technique for the processing of tubular specimens has been investigated. Commercially pure aluminum was selected for the study. Tubular specimens were extruded to three passes using four processing routes through an ECAP die with an angle of 150 between the two intersecting channels. Sand was used as a mandrel during the pressing. Analysis of force-stroke diagram was carried out. The mechanical properties were also investigated. Improvement in mechanical properties was observed in all the routes. These investigations demonstrate that ECAP is a promising technique for improving properties of tubular materials while ensuring retention of shape (with the possibility of imparting further deformation to the specimen using the same die) and with low pressing pressures. © Taylor and Francis Group, LLC.
Friction and dry sliding wear of bismaleimide filled with carbon nanotubes
(Taylor and Francis Ltd. maney@maney.co.uk, 2016) Kurahatti, R.V.; Surendranathan, A.O.; Mordina, B.; Naik, P.; Auradi, V.
Three types of bismaleimide–carbon nanotubes (CNTs) nanocomposites were fabricated using two types of original multiwalled CNTs with different diameters and one amide functionalized CNTs. The influence of diameter, content and functionalization of CNTs on the flexural and dry sliding wear behaviour were measured with universal testing machine and pin-on-disc wear apparatus. The experimental results indicated that at 1.5 wt-%, the bismaleimide-functionalized MWCNTs exhibited highest flexural strength of 156 MPa which is increased by 164% as compared to the neat matrix, and lowest specific wear rate of 1.8 × 10?4 mm3 N?1 m?1 which is decreased by 90% as compared to the neat matrix. This was attributed to the dispersion of CNTs in the matrix and the filler-matrix adhesion and internal strength of the composite. © 2016 Informa UK Limited, trading as Taylor & Francis Group.
Influence of oxidation on fracture toughness of carbon-carbon composites for high-temperature applications
(Gruppo Italiano Frattura, 2021) Sunil Kumar, B.V.S.; Londe, V.N.; Lokesha, M.; Vasantha Kumar, S.N.; Surendranathan, A.O.
Carbon-Carbon Composites (C-CC), used as composites for their remarkable qualities in the space industry and in many other industry sectors. C-CC has proven to be the most efficient material in extreme temperature situations. They are one among the best high-temperature materials with good thermal quality, such as high-temperature stability, outstanding thermal conductivity and low-temperature expansion coefficients. In aircraft, railways, trucks and even race vehicles, C-CC brake disks are in high demand. Compared to the favorable thermal and mechanical qualities of C-CC, their great sensitivity to oxidation in an oxidizing environment at temperatures even around 400°C is a major restriction with these composites. In particular, a study of the C-CC oxidation mechanism helps to create protective measures for these composites. The present experimental study explores the influence of oxidation in static air on the fracture toughness of C-CC. At a temperature of around 400°C to 700°C in an increment of 100°C, an oxidation evaluation of the material is carried out. Results show that there was a significant decrease in the fracture toughness when there was an increase in temperature from 400°C to 700°C. We can observe that C-CC fracture toughness is severely affected by oxidation. The decrease in the fracture toughness value in comparison with room temperature was 6% for 400°C and 45% for 700°C. © 2021.
Influence of Precracking Techniques on Fracture Toughness of Carbon-Carbon Composites
(Penerbit UTHM, 2021) Sunil Kumar, B.V.S.; Neelakantha, N.V.; Lokesha, M.; Surendranathan, A.O.
Abstract: Carbon-Carbon composites are one such material which give designers significant importance for advanced applications over conventional materials. The remarkable characteristics of carbon-carbon composites had made these products initially extremely useful in the field of aerospace and defense applications. Now, they are presently used in many applications such as biomedical implants, glass, and high temperature glass, etc. In material science, fracture toughness is a trait that depicts the ability of a material to withstand fractures and is one of the most important features in many design applications of any material. A precracked specimen is a sample that is used to accurately assess the distribution of cracks and it is a favored method. This paper describes a comparison of four precracking techniques for carbon-carbon composites using SENB specimen. The potential implications of these techniques on fracture toughness values have been evaluated. The outcome of this work indicates that precracking with a jewel saw is recommended over the other techniques. © 2021. UTHM Publisher. All rights reserved.
Investigation of microstructure and mechanical properties of microwave consolidated TiMgSr alloy prepared by high energy ball milling
(Elsevier B.V., 2022) Pradeep, N.B.; Rajath Hegde, M.M.R.; Rajendrachari, S.; Surendranathan, A.O.
The nanostructured TiMgSr (at.% 70:10:20) was synthesized by ball milling process followed by cold compaction and microwave sintering. XRD results after 30 h milling showed crystallite size of ⁓41 nm with a lattice strain of 2.5% and evolution of solid solutions like Mg5.2Sr, MgTiO3. The phases formed from 30 h mechanically alloyed powder are in good agreement with TEM SADP results. Consolidation using microwave sintering resulted in the retention of nanostructure with crystallite size of 78 nm and lattice strain of 1.2%. Densification study results in porosity of 19.8% with almost 20% density reduction compared to CP-Ti. The obtained porosity has promoted density reduction along with low elastic modulus that could be biocompatible with human bone tissue. Nanoindentation test results showed a low modulus of 36 ± 7 GPa with a hardness of 1.8 ± 0.8 GPa. These results are comparable with those Ti alloys produced by various techniques and found to be relatively superior for biomedical applications. © 2022
Investigation of Structural and Mechanical Properties of Nanostructured TiMgSr Alloy for Biomedical applications
(AMG Transcend Association, 2023) Pradeep, P.N.; Rajendrachari, S.; Surendranathan, A.O.; Rajath Hegde, M.M.R.
In this study, Nanostructured TiMgSr alloy is produced by cold Isostatic Pressing (CIP) followed by microwave sintering. The fabricated alloy results in the formation of solid binary solutions along with the elemental phases. The CIP compacted alloy was characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) to investigate the phases and the morphology. The presence of intermetallic phases SrTiO3 and Mg17 Sr2 along with elemental Ti, Mg, and Sr crystallites with a narrow peak during the sintering process is prevalent; however, the crystallite size was retained in the nanoscale regime around 58 nm. The developed titanium alloy exhibits a low Young's modulus and good strength. The young's modulus of Ti–Mg–Sr alloys was around 48.11 GPa, significantly closer to human cortical bone (10–30 GPa). Among so far developed Ti-based alloys, the CIP consolidated Ti-Mg-Sr alloy results in low young modulus and hardness. In the future, it may be used practically for biomedical applications. © 2022 by the authors.
Mechanical and tribological behaviour of epoxy reinforced with nano-Al2O3 particles
(2014) Kurahatti, R.V.; Surendranathan, A.O.; Ramesh, Kumar, A.V.; Auradi, V.; Wadageri, C.S.; Kori, S.A.
In the present work systematic study has been conducted to investigate the matrix properties by introducing nanosize Al2O3 (particle size 100 nm, 0.5-10 wt %) fillers into an epoxy resin. High shear mixing process was employed to disperse the particles into the resin. The experimental results indicated that frictional coefficient and wear rate of epoxy can be reduced at rather low concentration of nano-Al2O3. The lowest specific wear rate 0.7 � 10-4 mm3/Nm is observed for the composites with 1 wt.% which is decreased by 65% as compared to unfilled epoxy. The reinforcement of Al2O3 particles leads to improved mechanical properties of the epoxy composites. The results have been supplemented with scanning electron micrographs to help understand the possible wear mechanisms. � (2014) Trans Tech Publications, Switzerland.