Modelling and experimental investigation of process parameters in EDM of Si3N4 -TiN composites using GRA-RSM

Selvarajan L,M. Manohar,A. Udhaya kumar,P. Dhinakaran 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.1

Electric discharge machining (EDM) is a highly promising machining process of ceramics. This research is an out of the paradigm investigation of EDM on Si 3 N 4 -TiN with Copper electrode. Ceramics are used for extrusion dies and bearing balls and they are more efficient, effective and even have longer life than conventional metal alloys. Owing to high hardness of ceramic composites, they are almost impossible to be machined by conventional machining as it entirely depends on relative hardness of tool with work piece. Whereas EDM offers easy machinability combined with exceptional surface finish. Input parameters of paramount significance such as current (I), pulse on (P on ) and off time (P off ), Dielectric pressure (DP) and gap voltage (SV) are studied using L 25 orthogonal array. With help of mean effective plots the relationship of output parameters like Material removal rate (MRR), Tool wear rate (TWR), Surface roughness (Ra), Radial overcut (ROC), Taper angle (α), Circularity (CIR), Cylindricity (CYL) and Perpendicularity (PER) with the considered input parameters and their individual influence were investigated. The significant machining parameters were obtained by Analysis of variance (ANOVA) based on Grey relational analysis (GRA) and value of regression coefficient was determined for each model. The results were further evaluated by using confirmatory experiment which illustrated that spark eroding process could effectively be improved.

Preparation of bovine hydroxyapatite by transferred arc plasma

C.P. Yoganand,V. Selvarajan,O.M. Goudouri,K.M. Paraskevopoulos,Junshu Wu,Dongfeng Xue 한국물리학회 2011 Current Applied Physics Vol.11 No.3

Hydroxyapatite (Ca_10(PO_4)_6(OH)_2, abbreviated as HA) is a kind of bioactive material that has received considerable attention over the past decades as an implant material due to its excellent biocompatability for clinical applications. In this work, Hydroxyapatite was obtained by plasma processing of the natural bovine bones by Transferred arc plasma (TAP) processing at 5 kW in argon plasma for different processing times (i.e. 30, 45, 60, 90 and 120 s). The TAP synthesized HA bioceramic was characterized by XRD, FTIR,SEM-EDX and TG-DTA analysis. The effect of TAP processing time on the preparation of organic free HA from bovine bone was studied. The study indicated that TAP processing for 30, 45 and 60 s were insuf-ficient for removal of organics from the natural bovine bone. Organic free bovine HA was obtained for 90 s TAP processing with a Ca/P ratio of 1.93 comparable with commercially available natural HA-Endobon powder. Whereas 120 s of processing resulted in trivial thermal decomposition of HA in to its constituent phases. Thus our present investigation suggested that HA production from bovine bone using TAP processing is a time effective advantageous method in comparison to the annealing method.

Fabrication of mesoporous BaTiO3/SnO2 nanorods with highly enhanced photocatalytic degradation of organic pollutants

S. Selvarajan,P. Malathy,A. Suganthi,M. Rajarajan 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.53 No.-

Novel UV–vis-light-driven BaTiO3/SnO2 nanocomposites with three different molar ratios (1%, 3%, 5%) were synthesized by hydrothermal and precipitation deposition methods. The successfully characterized by UV-visible diffuse reflectance spectroscopy (DRS), FT-IR spectroscopy, X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM), photoluminescence spectroscopy (PL), and Brunauer–Emmett–Teller surface area analysis (BET) techniques. The lmax of the prepared nanocomposite was highly red shifted from 220 nm to 410 nm compared to the bare metal oxides. The degradation of organic pollutants such as o-Chloroaniline (o-CLA) and methylene blue (MB) were studied using the prepared nanocomposite. The nanocomposite with molar ratio of 3% BaTiO3/SnO2 photocatalyst possesses excellent photocatalytic activity than the nanocomposite with molar ratio 1% BaTiO3/SnO2, 5% BaTiO3/SnO2, and the individual components BaTiO3, SnO2. The band edges of materials have been theoretically calculated on the basis of Mullikan electronegativity of atoms. The effect of operational parameters such as; pollutant concentration, pH, catalyst loading, OH radical trapping and COD (carbon oxygen demand) have been investigated in details. The kinetics of the photodegradation reactions were correlated with the pseudofirst- order model. The stability of nanocomposite was examined by recycling experiments.

CaO–MgO–SiO2 glass ceramics: Transferred arc plasma (TAP) synthesis and microstructural characterization

C.P. Yoganand,V. Selvarajan,Luca Lusvarghi 한국물리학회 2009 Current Applied Physics Vol.9 No.4

In this paper, synthesis of CaO–MgO–SiO2 glass ceramic using transferred arc plasma (TAP) processing method is illustrated. Homogeneous mixture of 51.6% SiO2, 35.6% CaO and 12.8% MgO prepared by dry mixing in a ball mill was kept in the anode well (which is the melting bed) of the 10 kW transferred arc plasma torch. It was melted in plasma at an operating power of 5 kW (by varying the processing time for 3, 5 and 8 min). The melt was cooled to solidify by applying forced air on it. The resulting samples were characterized for microstructure and phase composition. The phases were identified by scanning electron microscopy (SEM), using the back-scattered electron (BSE) image mode and X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX). The microstructure was examined using optical microscopy (OM) and scanning electron microscopy. The micro-hardness, density and porosity measurements for the synthesized samples were carried out. Differential thermal analysis (DTA) was performed to study the thermal evolution. The results show the formation of diopside phase in the transferred arc plasma melted CaO–MgO–SiO2 glass ceramic system achieved with in a quite considerable short time of plasma processing. The method indicated that TAP technique could be a promising, time saving and onestep manufacturing process for the production of functional bulk glass ceramics. In this paper, synthesis of CaO–MgO–SiO2 glass ceramic using transferred arc plasma (TAP) processing method is illustrated. Homogeneous mixture of 51.6% SiO2, 35.6% CaO and 12.8% MgO prepared by dry mixing in a ball mill was kept in the anode well (which is the melting bed) of the 10 kW transferred arc plasma torch. It was melted in plasma at an operating power of 5 kW (by varying the processing time for 3, 5 and 8 min). The melt was cooled to solidify by applying forced air on it. The resulting samples were characterized for microstructure and phase composition. The phases were identified by scanning electron microscopy (SEM), using the back-scattered electron (BSE) image mode and X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX). The microstructure was examined using optical microscopy (OM) and scanning electron microscopy. The micro-hardness, density and porosity measurements for the synthesized samples were carried out. Differential thermal analysis (DTA) was performed to study the thermal evolution. The results show the formation of diopside phase in the transferred arc plasma melted CaO–MgO–SiO2 glass ceramic system achieved with in a quite considerable short time of plasma processing. The method indicated that TAP technique could be a promising, time saving and onestep manufacturing process for the production of functional bulk glass ceramics.

Synthesis, growth and studies of undoped and sodium chloride-doped Zinc Tris-thiourea Sulphate (ZTS) single crystals

C. Krishnan,P. Selvarajan,S. Pari 한국물리학회 2010 Current Applied Physics Vol.10 No.2

Single crystals of undoped (pure) and sodium chloride (NaCl)-doped Zinc Tris-thiourea Sulphate (ZTS)were grown from aqueous solutions by slow evaporation technique. Morphological alterations have been observed when NaCl is doped into ZTS crystals. Density of the grown crystals was measured by floatation method. The values of unit cell parameters from single crystal X-ray diffraction (XRD) studies show that pure and sodium chloride-doped ZTS crystals are in orthorhombic structure. Impurity concentration in the doped crystals was estimated by using an atomic absorption spectrometer. Second Harmonic Generation (SHG) test for the undoped and NaCl-doped ZTS crystals was performed by the powder technique of Kurtz and Perry using a pulsed Nd:YAG laser. Microhardness studies show that hardness number (Hv)increases with load for all the grown crystals of this work. From the values of work hardening coefficients,it is concluded that pure and sodium chloride-doped ZTS crystals belong to the category of soft materials. UV–vis–NIR spectra show that the grown crystals have wide optical transparency in the entire visible region. Birefringence studies of the grown samples have been performed by channelled spectrum method. The thermal stability of the materials is found to be increasing with the doping concentration of sodium chloride (NaCl) in the lattice of ZTS crystals.

Growth, structural, mechanical, spectral and dielectric characterization of NaCl-added Triglycine sulfate single crystals

N. Theresita Shanthi,P. Selvarajan,C.K. Mahadevan 한국물리학회 2009 Current Applied Physics Vol.9 No.5

Pure and sodium chloride (NaCl)-added Triglycine sulfate (TGS) crystals were grown from aqueous solutions by slow evaporation technique. The values of concentration of dopants in the mother solution were 0.2, 0.6 and 1 mol%. The solubility of the grown samples have been found out at various temperatures. The determination of unit cell parameters was carried out by single crystal XRD method and found that the grown crystals crystallize in monoclinic structure. The dielectric characterization for the pure and NaCl-doped TGS crystals was performed by measuring the dielectric parameters like dielectric constant and dielectric loss with various frequencies in the range 102–106 Hz and with the temperatures ranging from 30 to 70 ℃ and this study reveals an increase of dielectric constant and loss with the increase of NaCl concentration. Studies on mechanical properties like microhardness and density of the grown pure and NaCl-doped TGS crystals were carried out. UV–Visible transmittance studies were carried out for the grown samples. A sharp fall in the transmittance is observed at 228 nm for pure and NaCl-doped TGS crystals. Atomic absorption spectroscopic (AAS) study was done on the NaCl-doped TGS crystals to ascertain the presence of Na+ ions in the lattice.

Effect of powder loading on the excitation temperature of a plasma jet in DC thermal plasma spray torch

G. Shanmugavelayutham,V. Selvarajan,P.V.A. Padmanabhan,K.P. Sreekumar,N.K. Joshi 한국물리학회 2007 Current Applied Physics Vol.7 No.2

A DC non-transferred mode plasma spray torch was fabricated for plasma spheroidization. The eect of powder-carrier gas and pow-der loading on the temperature of the plasma jet generated by the torch has been studied. The experiment was done at dierent inputparticles in the size range from 40 to 100l m were processed. The temperature of the jet was estimated after owing powder-carrier gasonly into the plasma jet and with powder-carrier gas feeding powder into the ame. On introduction of powder-carrier gas and powderloading the temperature of the jet was found to decrease appreciably down to 11%. The temperature of the plasma jet was estimatedusing the Atomic Boltzmann plot method.

In-flight particle behaviour and its effect on co-spraying of alumina?titania

G. Shanmugavelayutham,V. Selvarajan,T.K. Thiyagarajan,P.V.A. Padmanabhan,K.P. Sreekumar,R.U. Satpute Y. Zhai 한국물리학회 2006 Current Applied Physics Vol.6 No.1

The present paper investigate and illustrate the importance of plasmaparticle interaction in controlling the plasma spray processwhile spraying aluminatitania powder blend. Plasma sprayed coatings of aluminatitania (6040l m) have been prepared at dier-chemical composition of aluminatitania coatings, prepared at low input power, is signicantly dierent from that of the feed stockpowder. Coating composition progressively approaches that of the feedstock powder at higher power inputs. Experimental resultsare explained in terms of the in-ight behaviour of alumina and titania particles in the plasma jet using a one-dimensional model topredict the thermal state of the particles. In particular, the eect of particle size and input power are considered in this study.