120 research outputs found

    Parametric optimization for hardness of tig welded duplex stainless steel

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    Achieving optimal mechanical properties in welding joints hinges on employing precise parametric conditions. This is particularly crucial for Tungsten Inert Gas (TIG) welding of ASTM/UNS 2205 Duplex Stainless Steel (DSS), where attributes like hardness, ultimate tensile strength, and yield strength are paramount. Maintaining high Hardness Value (HV) demands proper welding parameters such as welding current, gas flow rate, and welding speed. To enhance DSS welding quality, especially hardness, this study utilizes the Taguchi method to optimize welding process parameters. The importance of each factor is assessed through Annova statistical analysis. The outcomes highlight the positive impact of parametric optimization on HV, as evidenced by the analysed data. Parametric optimization proves to be a potent approach for refining industrial processes like welding, with particular relevance in TIG welding of duplex stainless steel due to its mechanical robustness and corrosion resistance. Nevertheless, challenges arise due to the material's elevated hardness and low thermal conductivity, resulting in potential defects like cracks and porosity. The identification of optimal welding parameters, encompassing current, voltage, speed, and gas flow rate, helps address these challenges and advances high-quality welds. Through systematic variations and analysis of these parameters, researchers and engineers can pinpoint the optimal combination that mitigates defects while maximizing desired joint attributes. Within the realm of TIG welding of duplex stainless steel, metric optimization holds the potential to elevate welding quality, curtail costs and waste, and heighten productivity and safety. Consequently, organizations can attain enhanced performance, efficiency, and profitability within their welding processe

    Optimization of process parameters of TIG welding of duplex stainless steel without filler rod by grey-Taguchi method

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    385-392Input parameters of welding have played an important role in producing the quality of welding joint. Welding quality has been improved using proper process parameters with sound knowledge base. Current, welding speed and the shielding gas flow rate have been used as the most important influencing parameters of Tungsten Inert Gas (TIG) welding on Duplex Stainless Steel (DSS). In the present work, multi-objective optimization of TIG welding process parameters of Duplex Stainless Steel - ASTM/UNS 2205 has been determined. These welding process parameters have been optimized to achieve the required quality of DSS welding joints. The quality of the TIG welding on DSS has been evaluated in term of tensile test. The grey-based Taguchi technique has been used to solve this multi- optimization problem. Analysis of Variance (ANOVA) has been applied to evaluate the significance of the individual factors on desired results which are ultimate tensile strength, yield strength and percentage of elongation. Additional confirmatory experiment has been done to verify the optimal results. The application possibilities of the grey-based Taguchi method for incessant development of welding quality of DSS in many fields, like chemical industries, oil refineries, gas manufacturing industries etc. have been shown by this work

    Optimization of process parameters of TIG welding of duplex stainless steel without filler rod by grey-Taguchi method

    Get PDF
    Input parameters of welding have played an important role in producing the quality of welding joint. Welding quality has been improved using proper process parameters with sound knowledge base. Current, welding speed and the shielding gas flow rate have been used as the most important influencing parameters of Tungsten Inert Gas (TIG) welding on Duplex Stainless Steel (DSS). In the present work, multi-objective optimization of TIG welding process parameters of Duplex Stainless Steel - ASTM/UNS 2205 has been determined. These welding process parameters have been optimized to achieve the required quality of DSS welding joints. The quality of the TIG welding on DSS has been evaluated in term of tensile test. The grey-based Taguchi technique has been used to solve this multi- optimization problem. Analysis of Variance (ANOVA) has been applied to evaluate the significanc e of the individual factors on desired results which are ultimate tensile strength, yield strength and percentage of elongation. Additional confirmatory experiment has been done to verify the optimal results. The application possibilities of the grey-based Taguchi method for incessant development of welding quality of DSS in many fields, like chemical industries, oil refineries, gas manufacturing industries etc. have been shown by this work

    On the non-innocence and reactive: Versus non-reactive nature of α-diketones in a set of diruthenium frameworks

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    α-Diketones are an important class of building blocks employed in many organic synthetic reactions. However, their coordination chemistry has rarely been explored. In light of this, our earlier report on [(acac)2RuII(μ-2,2′-pyridil)RuII(acac)2] (acac = acetylacetonate) showcased the sensitivity of a diketone fragment towards oxidative C-C cleavage. Following the lead, the synthesis of similar but stable diketo fragments containing diruthenium compounds was attempted. Three diruthenium compounds with the bridge 1,2-bis(2-hydroxyphenyl)ethane-1,2-dione (L) were prepared: diastereomeric [(acac)2RuIII(μ-L2-)RuIII(acac)2], 1a(rac)/1b(meso), [(bpy)2RuII(μ-L2-)RuII(bpy)2](ClO4)2, [2](ClO4)2 and [(pap)2RuII(μ-L2-)RuII(pap)2](ClO4)2, [3](ClO4)2 with ancillary ligands of different donating/accepting characteristics. The metal is stabilised in different oxidation states in these complexes: Ru(iii) is preferred in 1a/1b when σ-donating acac is used as the co-ligand whereas electron rich Ru(ii) is preferred in [2](ClO4)2 and [3](ClO4)2 when co-ligands of moderate to strong π-Accepting properties are employed. The oxidative chemistry of these systems is of particular interest with respect to the participation of varying bridging-ligands which contain phenoxide groups. On the other hand, the reduction processes primarily resulting from the metal or the ancillary ligands are noteworthy as the normally reducible 1,2-diketo-group remains unreduced. These results have been rationalised and outlined from thorough experimental and theoretical investigations. The results presented here shed light on the stability of metal coordinated α-diketones as a function of their substituents.Fil: Khan, Farheen Fatima. Indian Institute Of Technology, Bombay; IndiaFil: Mondal, Saikat. Indian Institute Of Technology, Bombay; IndiaFil: Chandra, Shubhadeep. Universität Stuttgart; AlemaniaFil: Neuman, Nicolás Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Sarkar, Biprajit. Universität Stuttgart; AlemaniaFil: Lahiri, Goutam Kumar. Indian Institute Of Technology, Bombay; Indi

    Mosquito larvicidal and antimicrobial activities of synthesized silver nanoparticles (AgNP) using mature fruit extract of Cestrum diurnum L.

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    592-599Silver nanoparticles (AgNP) were prepared using mature fruit extract of Cestrum diurnum L. (family: Solanaceae) as a reducing agent. The stabilized AgNPs were characterized by time-dependent UV–Vis Spectrophotometric analysis. The spherical/oval shape of the nanoparticle was confirmed by Transmission Electron Microscopy analysis with an average particle size of about 50 nm. The crystalline nature of the AgNPs was confirmed in the XRD spectrum by the characteristic Bragg peaks. Fourier Transform Infrared Spectroscopic analysis of AgNPs confirms the presence of several functional groups. AgNPs showed effective larvicidal activities against larval instars of Anopheles stephensi and Culex quinquefasciatus mosquitoes in the laboratory bioassay. Synthesized AgNPs also showed good antibacterial activity against some fish pathogenic and human pathogenic bacteria which is evident from the inhibition zone diameter in the antibacterial bioassay experiment

    Synthesis, structure, spectral and electron-transfer properties of octahedral-[Co<SUP>III</SUP>(L)<SUB>2</SUB>]<SUP>+</SUP>/[Zn<SUP>II</SUP>(L)<SUB>2</SUB>] and square planar-[Cu<SUP>II</SUP>(L){OC(=O)CH<SUB>3</SUB>}] complexes incorporating anionic form of tridentate bis(8-quinolinyl)amine [N<SUP>1</SUP>C<SUB>9</SUB>H<SUB>6</SUB>-N<SUP>2</SUP>-C<SUB>9</SUB>H<SUB>6</SUB>N<SUP>3</SUP>, L<SUP>-</SUP>] ligand

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    The reaction of bis(8-quinolinyl)amine [N1C9H6-N2H-C9H6N3, LH] with CoII(ClO4)2 . 6H2O in methanol under aerobic conditions results in a new class of [CoIIIN6]+ (1+) chromophore incorporating an sp2-amido nitrogen center (N2) in the ligand frame. During the course of the reaction, the cobalt ion has been oxidized from its starting +2 oxidation state to +3 state in 1. The reaction of LH with the Cu-acetate yields monomeric square planar complex, [CuII(L){OC(=O)CH3}] (2). The same copper complex 2 is also obtained from Cu(ClO4) . 6H2O in presence of CH3COONa as base. On the other hand, the reaction of Zn(ClO4) . 6H2O with LH results in octahedral complex ZnII(L)2 (3). The Cu(II) complex 2 displays a four-line EPR spectrum at room temperature. Crystal structure of the free ligand (LH) shows that the amine proton [N(2)H] is hydrogen-bonded with the terminal quinoline nitrogen centers [N(1) and N(3)]. The crystal structure of 1 confirms the meridional geometry of the complex cation. The square planar geometry of copper complex 2 is confirmed by its crystal structure where the acetate function behaves as a monodentate ligand. The free ligand, LH, is found to be highly acidic in acetonitrile-water (1:1) medium and correspondingly the amine proton (NH) readily dissociates leading to its L- form even in absence of any external base. The pKb value of L- is determined to be 2.6. Both cobalt and copper complexes do not show any expected spin-allowed d-d transitions, possibly have masked by the intense charge-transfer transitions. However, in case of cobalt complex 1, one very weak unusual spin-forbidden 1A1g &#8594; 3T1g transition has been observed at 935 nm. The quasi-reversible cobalt (III)&#8596; cobalt(II) reduction of 1 is observed at E0, -1.0 V versus SCE. The reactions of bis(8-quinolinyl)amine [N1C9H6-N2H-C9H6N3, LH] with CoII(ClO4)2 . 6H2O, ZnII(ClO4)2 . 6H2O and CuII-acetate result in octahedral-[CoIII(L-)2]+ and [ZnII(L-)2] and square planar-[CuII(L-){-OC(=O)CH3}] complexes, respectively, incorporating an sp2-amido nitrogen center (N2) in the coordinated ligand frame of L. The structural, spectral and electrochemical aspects of the complexes have been described

    Role of offending out-door aero-allergen and CD14 C(-159)T polymorphism in development and severity of asthma in a Kolkata patient population

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    Objective: Present study involved identification of offending out-door aero-allergens and associated genetic pathway in nasso-bronchial asthma among Kolkata population.Methods: Skin-prick test was done among 950 asthmatic patients against 11 common aero-allergens and total serum IgE concentration was measured. PCR-RFLP was done in patients and non-asthmatic control (n=220 in each) to characterize functional polymorphism, C(-159)T, of CD14, a positional candidate gene for allergy. Association of genetic polymorphisms was made with clinico-pathological conditions.Results: We identified Cocos nucifera as the most common aero-allergen sensitizer among atopic patients in Kolkata. Patients with childhood-onset asthma were significantly more sensitive towards aero-allergens and had significantly higher serum IgE level than those of adult-onset (p&lt; 0.0001). No significant difference was found in distribution of SNP genotypes of CD14 among case and control (p=0.178). However among patients, frequency of C allele is significantly higher in childhood-onset group thanthat of adult-onset and concordantly in former CC genotype was associated with significant higher level of serum IgE than CT and TT.Conclusion: In Kolkata, pollen is a common out-door aero-allergen and Cocos nucifera is predominant among pollens. Childhood- onset and adult-onset of asthma showed significant difference in allergen sensitivity as well as genetic background with respect to CD14 polymorphism.Keywords: Asthma, aero-allergen, skin prick test, total IgE, CD14 gene polymorphis
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