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Evaluation of cutting forces and temperature of iron-rich binder carbide tool in turning of titanium

Mahadevaiah C., Prasad S.

Engineering Transactions

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2018

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Vol. 66, iss. 3

325--338

EN

The machining of titanium has been understood to be challenging and costly due to its material properties such as low thermal conductivity, low modulus of elasticity, high strength at elevated temperatures and chemical reactivity. This work aims to study the effect of iron as a partial substitution along with cobalt binder as the tool material for machining of titanium alloy. In this work, iron-rich binder tool (WC-Co-Fe) and cobalt binder tool (WC-Co) samples were produced by powder metallurgy route using powders with a mean particle size of less than 0.5 µm. Next, the evaluation of mechanical properties and phase analysis were performed. Turning experiments were conducted at various cutting speeds, feed and depth of cut (DOC), to evaluate the effects of iron-rich binder on flank wear, cutting forces and cutting temperature. The obtained results of turning experiments reveal that iron-rich binder tends to increase cutting performance in comparison to conventional WC-Co composite cutting tools.

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Performance study of a liquid-core Bragg fiber sensor in presence of a defect layer

Chourasia R. K., Prasad S., Singh V.

Opto-Electronics Review

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2017

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Vol. 25, No. 3

215--221

EN

Performance parameter of a Bragg fiber waveguide based resonant sensor in presence of a defect layer in cladding regions is theoretically studied. The Bragg fiber waveguide consists of a liquid-core surrounded by alternate high and low refractive indices materials in cladding regions. Reflectivity of the proposed waveguide based resonant sensor is formulated using transfer matrix method for a non-homogeneous multilayer cylindrical system. The waveguide shows a band gap region with a narrow defect mode in the band gap region under the considered wavelength range. Instead of taking a whole band gap as a sensing signal, here the defect peak is taken as the sensing signal. It is observed that the intensity of defect mode is more sensitive for core refractive index than the intensity of traditional band gap region (lobe). This study shows that the higher sensitivity can be achieved by creating the defect at a position in cladding region where the intensity of transmitted light lies between 40% and 90%. Presence of a defect layer is able to increase the detection accuracy of the sensor and, hence increase the overall performance of this sensor.

3

Electrical properties of 0.90Pb[(Mg,Zn)1/3Ta2/3]O3-0.10PbTiO3 relaxor

Prasad S., Prasad K., Choudhary S.N., Sinha T.P.

Materials Science Poland

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2008

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Vol. 26, No. 3

475--485

EN

Polycrystalline 0.90Pb[(Mg2/3Zn1/3)1/3Ta2/3] O3-0.10PbTiO3 having a tetragonal perovskite type structure was prepared by the high temperature solid-state reaction method. Dielectric studies showed the relaxor behaviour with diffuse phase transition. High value of ∈max > 10000 was realized with the temperature of the permittivity maximum (Tm) around room temperature at 1 kHz. The frequency dependence of Tm has been modeled using Vogel-Fulcher relation. The dielectric relaxation in the present system was found analogous to the magnetic relaxation in spin-glass system. The shape of the complex impedance curve indicated that the system exhibited almost Debye type dielectric relaxation at 350 °C, where as non-Debye character was observed at temperatures ≥ 325 °C. Further the relaxation frequency was found to shift towards higher frequencies with an increase in temperature.