Densification and Deformation Behavior of Sintered P/M Zinc-Zinc Oxide Composite during Cold Upsetting
Studies were carried out to evaluate the initially preformed density and initial aspect ratio on the densification behavior of sintered Zinc and Zinc Oxide composite. The preform possessed 0.85 is the initial density. Aspect ratio for three different oxidizing temperatures (at 150°C, 200°C and 250°C) varied from 0.4 to 0.85. Properties of Zinc-Zinc Oxide composites with respect to linear strain, lateral strain and true stress were evaluated and plotted. Studies revealed that higher stress and higher strain values are obtained in composite when compared to the Zinc dust. The composite of Zinc-Zinc Oxide obtained at 150 o C possessed the highest stress and strain when compared to the composites obtained at others two temperatures (200 o C and 250 o C).
DENSIFICATION AND DEFORMATION BEHAVIOUR OF SINTERED POWDER METALLURGY COPPER-7%TUNGSTEN COMPOSITE DURING COLD UPSETTING
Studies were conceded out to evaluate the initially preformed density and initial aspect ratio on the densification behavior of sintered Copper 7% Tungsten composite. The preform possessed 0.85 is the initial theoretical density. Aspect ratio varied from 0.4, 0.6 and 0.8. Properties of Copper Tungsten composites with respect to linear strain, lateral strain and true stress were evaluated and plotted. Studies exposed that higher stress and higher strain values are obtained in composite when compared to the Tungsten powder. The composite of Copper 7%W obtained at 750 o C. The Composite obtained at lower aspect ratio acquired the highest stress and strain when compared to the composites preforms obtained at other aspect ratio
Inhibition of Mild Steel Corrosion Using L-tryptophan and Synergistic Surfactant Additives
The corrosion inhibition characteristics of nitrogen containing amino acid L-tryptophan on mild steel in 0.1 M HCl solution, in the temperature range of 30-50 o C, was studied by weight loss and potentiodynamic polarization measurements. L-tryptophan significantly reduces the corrosion rates of mild steel; the maximum inhibition efficiency being 83% at 50 o C in presence of inhibitor concentration of 500 ppm. The effect of the addition of very small concentrations of anionic surfactant, sodium dodecyl sulfate (SDS), and of cationic surfactant, cetyl trimethyl ammonium bromide (CTAB), on the corrosion inhibition behavior of L-tryptophan was also studied. The inhibition efficiency (IE) of L-tryptophan significantly improved in presence of both surfactants. The effect of SDS and CTAB on the corrosion inhibition behavior of L-tryptophan appears to be synergistic in nature, the values of synergism parameter being greater than unity. The adsorption of inhibitors on mild steel surface obeyed Langmuir’s adsorption isotherm. The calculated thermodynamic parameters for adsorption reveal a strong interaction between the inhibitors and the mild steel surface. The results obtained by electrochemical studies are consistent with the results of the weight loss measurements. L-tryptophan acts more anodic than cathodic inhibitor.