Effect of TiB2/Gr Hybrid Reinforcements in Al 7075 Matrix on Sliding Wear Behavior Analyzed by Response Surface Methodology

S. Sivasankaran,K. R. Ramkumar,Fahad A. Al‑Mufadi,Osama M. Irfan 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.6

Al 7075 alloy matrix reinforced with different weight percentage of titanium borides (TiB2, 0, 1.5, 3, 4.5 and 6 wt%) and1 wt% graphite (Gr) hybrid composites were synthesized by in-situ liquid metallurgy route, then the sliding wear characteristicswere performed and investigated in this research work. TiB2reinforced as 0, 1.5, 3, 4.5 and 6 wt% by the in situchemical reaction of KBF4and K2TiF6salts and 1 wt% Gr with the Al 7075 matrix were added constantly in the melt. Severalexperiments were carried out to examine the wear behavior of the fabricated composite specimens through a tribometer atambient temperature. The weight percentage of reinforcement (TiB2 particles), the applied load, the sliding velocity (SV),and the sliding distance (SD) were selected as process parameters at five different levels. The response surface methodology(RSM) was used to conduct the experiments as RSM is the feasible and accurate method employed for optimizing to set theparameters. To check the significance of the developed model by RSM, ANOVA and confirmatory tests were also accomplished. FESEM surface morphology was also carried out to illustrate the uniform dispersion of the TiB2–Gr particulatesin Al 7075 matrix. The predicted wear characteristics from the developed model were well agreed with the experimentalresults. The obtained results were explained that both the increase in the percentage of RF and SV have dropped the wearloss (WL) curve whereas the load at all SVs and the SDs were uplifted the WL. The worn surface morphology explainedthat the adhesive mechanisms were dominated during the sliding wear test. Further, severe and mild wear occurred duringhigher load and lower load respectively.

Retardation of Grain Growth in Al 3003 Nanocomposite Weldment Using ARB Filler Metal

K. R. Ramkumar,S. Natarajan 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7

This research demonstrates the feasibility of fller rod fabrication to develop nanocomposite weldment to enhance the jointstrength via ARB technique. Al 3003 alloys were joined through GTAW by melting fabricated nanocomposite fller metal. TiO2 nanoparticles were chosen as reinforcement from 0 to 3 wt%. Roll bonding is desired owing to the proper distributionof TiO2 particles. SEM depicted the distribution of reinforcement particles in the grain boundaries. TEM disclosed theuniformity in particulates distribution, peening of dislocation and strain felds in 12 wt% TiO2 reinforced nanocompositeweldment. EBSD portrayed the grain refnement occurred in the weld zone due to reinforcement addition. The improvementin impact and bending strength were due to excellent bonding between the Al and reinforcement particles and excellent loadtransfer ability provided by reinforcement particles.

Combined effects of direct plasma exposure and pre-plasma functionalized metal-doped graphene oxide nanoparticles on wastewater dye degradation

K. Navaneetha Pandiyaraj,D. Vasu,A. Raji,Rouba Ghobeira,Parinaz Saadat Esbah Tabaei,Nathalie De Geyter,Rino Morent,M.C. Ramkumar,M. Pichumani,R.R. Deshmukh 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.122 No.-

The current study investigates the combinatorial effect of the photocatalytic performance of plasma pretreatedTi-Cu-Zn doped graphene oxide (TCZ-GO) nanoparticles (NPs) and advanced oxidation processesof a non-thermal atmospheric pressure plasma on the degradation of reactive orange-122 (RO-122) dyecompounds. Firstly, in order to enhance the photocatalytic performance of the synthesized compositeNPs, they were subjected to glow discharge plasma treatments operating in different gases (Ar, air, O2and N2). Their surface morphology, chemical composition and band gap were examined by means ofscanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and UV–Vis spectrophotometryrespectively. XPS results revealed that plasma-treated NPs exhibited a higher content of oxygenvacancies and a variation in their oxidation states (Ti4+?Ti3+, Cu+?Cu2+). These plasma-induced surfacechemical changes hindered the recombination of photo-generated electron-hole pairs which led to a dropin the bandgap of the NPs with N2 plasma-treated NPs acquiring the lowest bandgap. Lastly, the articleexamined the actual decomposition of RO-122 dye in wastewater by an Ar plasma treatment alone orcombined with the plasma-treated TCZ-GO NPs via spectrophotometric analyses, electrical conductivity,pH and total organic carbon (TOC) removal measurements. Moreover, the reactive species produced duringthe combined plasma/photocatalysis induced degradation were detected in situ by optical emissionspectroscopy. Results revealed that the processes carried out by combining N2 plasma-treated TCZ-GONPs and Ar plasma exhibited the highest degradation efficiency (85 %) due to the generation of moreOH and H2O2. Overall, it can be concluded that plasma-aided treatment processes used synergisticallyas indirect surface functionalization of TCZ-GO NPs and direct plasma treatment of wastewater are extremelyefficient in the degradation of toxic compounds and can be extrapolated to various environmentalapplications.

Tracing the footprints of the ABCDE model of flowering in Phalaenopsis equestris (Schauer) Rchb.f. (Orchidaceae)

Jaspreet K. Sembi,Himani,Thakku R. Ramkumar,Shivi Tyagi,Himanshu Sharma,Santosh K. Upadhyay 한국식물생명공학회 2019 JOURNAL OF PLANT BIOTECHNOLOGY Vol.46 No.4

Orchids are indispensable to the floriculture industry due to their unique floral organization. The flowers have two outer whorls of tepals including a lip (labellum), and two inner whorls, pollinia and gynostemiun (column). The floral organization and development is controlled at the molecular level, mainly by the MADS-box gene family, comprising homeotic genes divided into type I and type II groups. The type I group has four sub-groups, Mα, Mβ, Mγ, and Mδ, playing roles in seed, embryo, and female repro-ductive organ development; the type II group genes form classes A, B, C, D, and E, which are a part of the MIKCC subgroup with specific roles in florigenesis and organization. The coordinated functioning of these classes regulates the development of various floral whorls. The availability of genome and transcriptome sequence data for Phalaenopsis equestris offers an opportunity to validate the ABCDE model of flower development. Hence, this study sought to characterize the MADS-box gene family and elucidate of the ABCDE model. A total of 48 identified MADS-box proteins, including 20 type I [Mα (12), Mγ (8)] and 28 type II [MIKCC (27), MIKC* (1)] members, were characterized for physico-chemical features and domains and motifs organization. The exon-intron distribution and the upstream cis-regulatory elements in the promoter regions of MADS-box genes were also analysed. The discrete pace of duplication events in type I and type II genes suggested differential evolutionary constraints between groups. The correlation of spatio-temporal expression pattern with the presence of specific cis-regulatory elements and putative protein–protein interaction within the different classes of MADS-box gene family endorse the ABCDE model of floral development.

Tracing the footprints of the ABCDE model of flowering in Phalaenopsis equestris (Schauer) Rchb.f. (Orchidaceae)

Himani, Himani,Ramkumar, Thakku R.,Tyagi, Shivi,Sharma, Himanshu,Upadhyay, Santosh K.,Sembi, Jaspreet K. The Korean Society of Plant Biotechnology 2019 식물생명공학회지 Vol.46 No.4

Orchids are indispensable to the floriculture industry due to their unique floral organization. The flowers have two outer whorls of tepals including a lip (labellum), and two inner whorls, pollinia and gynostemiun (column). The floral organization and development is controlled at the molecular level, mainly by the MADS-box gene family, comprising homeotic genes divided into type I and type II groups. The type I group has four sub-groups, Mα, Mβ, Mγ, and Mδ, playing roles in seed, embryo, and female reproductive organ development; the type II group genes form classes A, B, C, D, and E, which are a part of the MIKC^C subgroup with specific roles in florigenesis and organization. The coordinated functioning of these classes regulates the development of various floral whorls. The availability of genome and transcriptome sequence data for Phalaenopsis equestris offers an opportunity to validate the ABCDE model of flower development. Hence, this study sought to characterize the MADS-box gene family and elucidate of the ABCDE model. A total of 48 identified MADS-box proteins, including 20 type I [Mα (12), Mγ (8)] and 28 type II [MIKC^C (27), MIKC*(1)] members, were characterized for physico-chemical features and domains and motifs organization. The exon-intron distribution and the upstream cis-regulatory elements in the promoter regions of MADS-box genes were also analysed. The discrete pace of duplication events in type I and type II genes suggested differential evolutionary constraints between groups. The correlation of spatio-temporal expression pattern with the presence of specific cis-regulatory elements and putative protein-protein interaction within the different classes of MADS-box gene family endorse the ABCDE model of floral development.

Two Statistical Scrutinize of Impact Strength and Strength Reliability of Steel Fibre-Reinforced Concrete

G. Murali,R. Gayathri,V. R. Ramkumar,K. Karthikeyan 대한토목학회 2018 KSCE Journal of Civil Engineering Vol.22 No.1

The variations in impact strength of steel Fibre Reinforced Concrete (FRC) were statistically, commanded in this research. For this purpose, the experimental impact test results of earlier researchers were investigated using two statistical approaches. Firstly, normality test was carried out on first crack strength (N1) and failure strength (N2) using distribution plot and its accuracy was verified with Kolmogorov-Smirnov, Shapiro-Wilk and Chen-Shapiro test. Secondly, strength reliability analysis was carried out using two parameter Weibull distribution and their Weibull parameters were determined using three methods viz., Empherical Method of Justus (EMJ), Method of Moments (MOM) and Empherical Method of Lysen (EML). Results suggested that, if three samples are used to determine the N1 value for researchers’ data, at 95% levels of confidence, then the error in the measured value is about 50%. The 0.1 reliability level of the impact strength values of EMJ, EML and MOM were 153, 120 and 153 respectively in case of N1 and were 198, 156, and 198 respectively in case of N2 based on earlier researcher’s data.

Microstructural Evolutions, Hot Deformation and Work Hardening Behaviour of Novel Al–Zn Binary Alloys Processed by Squeezing and Hot Extrusion

S. Sivasankaran,K. R. Ramkumar,Hany R. Ammar,Fahad A. Al‑Mufadi,Abdulaziz S. Alaboodi,Osama Mohamed Irfan 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.4

The main goals of this work were to manufacture novel Al–Zn extruded alloys by varying the Zn content (0, 10, 20, 30 wt%),investigate the microstructural evolutions, hot deformation, and work hardening behaviour by hot compression test at differenttemperatures (25 °C, 75 °C, 150 °C, 225 °C, 300 °C). Al–20Zn alloy microstructure revealed α-Al and uniform distributionof (α + η) phases, coherent (α + η) crystals in GBs with casting defect-free surfaces, and effective interactions of pinningdislocations which led to improve mechanical performance of Al–20Zn alloy, as compared to the other alloys. The observedengineering stress–strain curve results revealed the decrease of stress with increasing of temperature due to flow softening,dynamic recovery and dynamic recrystallization. These results displayed also an increase of stress value with increasingof Zn content due to the precipitation of high density (α + η) phase in the matrix and GBs, increasing of forest and mobiledislocations density with strain fields, and the formation of fine dendrites. Work hardening rate (WHR) of extruded samplesdisplayed three stages: stage I, WHR decreased slightly with increasing of temperature up to 75 °C and decreased drasticallyfrom 75 °C to 300 °C due to softening; stage II, WHR maintained constant due to balance between dislocation generationsand dislocation annihilation; stage III, WHR slightly increased due to strain hardening of (α + η) phase. WHR was observedto increase considerably with increasing of Zn content due to the formation and dispersion of high density of (α + η) phasein the Al matrix and GBs. Deformation micro-localization in terms of different characteristics was examined and reportedon the deformed samples after hot-compression test through SEM micrographs.

Analysis of flexural fatigue failure of concrete made with 100% coarse recycled and natural aggregates

G. Murali,T. Indhumathi,K. Karthikeyan,V.R. Ramkumar 사단법인 한국계산역학회 2018 Computers and Concrete, An International Journal Vol.21 No.3

In this study, the flexural fatigue performance of concrete beams made with 100% Coarse Recycled Concrete Aggregates (RCA) and 100% Coarse Natural Aggregates (NA) were statistically commanded. For this purpose, the experimental fatigue test results of earlier researcher were investigated using two parameter Weibull distribution. The shape and scale parameters of Weibull distribution function was evaluated using seven numerical methods namely, Graphical method (GM), Least-Squares (LS) regression of Y on X, Least-Squares (LS) regression of X on Y, Empherical Method of Lysen (EML), Mean Standard DeviationMethod (MSDM), Energy Pattern FactorMethod (EPFM) andMethod of Moments (MOM). The average of Weibull parameters was used to incorporate survival probability into stress (S)-fatigue life (N) relationships. Based on the Weibull theory, as single and double logarithm fatigue equations for RCA and NA under different survival probability were provided. The results revealed that, by considering 0.9 level survival probability, the theoretical stress level corresponding to a fatigue failure number equal to one million cycle, decreases by 8.77% (calculated using single-logarithm fatigue equation) and 6.62%(calculated using double logarithm fatigue equation) in RCAwhen compared to NAconcrete.

Development of Thiourea-Formaldehyde Crosslinked Chitosan Membrane Networks for Separation of Cu (II) and Ni (II) Ions

Sudhavani, T.J.,Reddy, N. Sivagangi,Rao, K. Madhusudana,Rao, K.S.V. Krishna,Ramkumar, Jayshree,Reddy, A.V.R. Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.5

Novel chitosan (CS) based membrane networks were developed by solution casting and followed by crosslinking with different crosslinkers such as glutaraldehyde, urea-formaldehyde, and thiourea-formaldehyde. The developed membrane networks were designated as CS-GA, CS-UF and CS-TF. Crosslinking reaction of CS membranes was confirmed by Fourier transform infrared spectroscopy. Membrane rigidity and compactness were studied by the differential scanning calorimetry. The surface morphology of CS membranes was characterized by scanning electron microscopy. The sorption behaviour with respect to contact time, initial pH and initial metal ion concentration were investigated. The maximum adsorption capacity of CS-GA, CS-UF and CS-TF sorbents was found to be 1.03, 1.2 and 1.18 mM/g for $Cu^{2+}$ and 1.48, 1.55 and 2.18 mM/g for $Ni^{2+}$ respectively. Swelling experiments have been performed on the membrane networks at $30^{\circ}C$. Desorption studies were performed in acid media and EDTA and it was found that the membranes are reusable for the metal ion removal for three cycles. The developed membranes could be successfully used for the separation of $Cu^{2+}$ and $Ni^{2+}$ metal ions from aqueous solutions.

Microstructural and Wear Behaviour of Al 6063–W Nanocomposites Developed Using Friction Stir Processing

L. Feroz Ali,N. Kuppuswamy,R. Soundararajan,K. R. Ramkumar,S. Sivasankaran 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.12

The goal of the present research is to introduce the Tungsten (W) nanoparticles as reinforcement into Al 6063 alloy to produceAl–W nanocomposites by the FSP technique. The vol% of the reinforcement was varied from 3 to 12 with a step of 3,besides the unreinforced Al matrix was considered as 0 vol% for comparison. The role of W nanoparticles in the Al 6063matrix has been exhaustively investigated using advanced characterization techniques such as XRD analysis to observe thephases, FESEM to detect the distribution of reinforcements with their interparticle spacing and the average grain sizes, TEManalysis to study the strengthening factors, new phase formation at the interface between AA 6063 matrix and W particles,the morphology of the W nanoparticles. The achieved average matrix grains size was 42, 2, and 0.9 μm for 0, 6, and 12vol% W nanocomposites, respectively. The obtained results disclosed the uniform dispersion of W nanoparticles, withoutany agglomeration, and with the absence of intermetallic compounds. The hardness and wear resistance of the fabricatednanocomposites were increased incommensurate with the incorporation of heavy metallic W element as reinforcementparticle; which was due to the proper dispersion of W nanoparticles, refinement of matrix grains to ultrafine level, generationof dislocations, and clear interface between Al 6063 matrix and W nanoparticles. In a nutshell, AA 6063–12 vol% Wnanocomposite has achieved the higher hardness (120 HV), lower wear rate (0.13 mm3/m), and friction coefficient (0.33)than other nanocomposites.