Comparative study of machinability characteristics during machining nimonic c-263 with uncoated and cvd multicoated carbide inserts

Nickel base super alloy has the combined property of “high mechanical strength” and “High heat and corrosion resistance” at elevated temperature. This is the reason for which Nickel based super alloy are extremely used in 1. Aircraft gas turbine engine due to their superior mechanical property at an elevated temperature, 2. Aerospace component which continuously suffer from Extreme temperature, pressure and velocity for long period, 3. Submarine and chemical industries due to Superior Chemical properties like resistance to corrosion and oxidation, 4. Heat exchanger as subjected to high temperature. Super alloy are difficult to machine due to their high mechanical strength and low thermal conductivity resulting tool wear during machining. Work hardening occur rapidly during machining resulting notching. Chemical reaction occur at high cutting temperature produce diffusion wear during machine. Low thermal conductivity of super alloy results tool wear, which accelerate premature tool failure, short tool life, increase of cutting forces and poor quality of surface finish. NIMONIC is high temperature low-creep super alloy .Major constituents of NIMONIC is nickel , Chromium and cobalt which enhance the resistance to corrosion and oxidation for which NIMONIC got higher chemical property compared to Inconel in which (5-10)% iron concentration present. NIMONIC C-263 alloy has immense uses recent times as mentioned above hence it is necessary to study the machinability aspect of super alloy in order to enhance and productivity of the super alloy. Tool performance were studied ,when C-263 super alloy is machined under coated and uncoated carbide tool insert at dry condition .The operation were performed keeping feed (0.2mm/rev)and depth of cut (1mm) and varying cutting velocity (51-84)m/mi

General relativistic treatment of LISA optical links

LISA is a joint space mission of the NASA and the ESA for detecting low frequency gravitational waves in the band $10^{-5} - 1$ Hz. In order to attain the requisite sensitivity for LISA, the laser frequency noise must be suppressed below the other secondary noises such as the optical path noise, acceleration noise etc. This is achieved by combining time-delayed data for which precise knowledge of time-delays is required. The gravitational field, mainly that of the Sun and the motion of LISA affect the time-delays and the optical links. Further, the effect of the gravitational field of the Earth on the orbits of spacecraft is included. This leads to additional flexing over and above that of the Sun. We have written a numerical code which computes the optical links, that is, the time-delays with great accuracy $\sim 10^{-2}$ metres - more than what is required for time delay interferometry (TDI) - for most of the orbit and with sufficient accuracy within $\sim 10$ metres for an integrated time window of about six days, when one of the arms tends to be tangent to the orbit. Our analysis of the optical links is fully general relativistic and the numerical code takes into account effects such as the Sagnac, Shapiro delay, etc.. We show that with the deemed parameters in the design of LISA, there are symmetries inherent in the configuration of LISA and in the physics, which may be used effectively to suppress the residual laser noise in the modified first generation TDI. We demonstrate our results for some important TDI variables

Pressure induced magnetic and magnetocaloric properties in NiCoMnSb Heusler alloy

The effect of pressure on the magnetic and the magnetocaloric properties around the martensitic transformation temperature in NiCoMnSb Heusler alloy has been studied. The martensitic transition temperature has significantly shifted to higher temperatures with pressure, whereas the trend is opposite with the application of applied magnetic field. The maximum magnetic entropy change around the martensitic transition temperature for Ni45Co5Mn38Sb12 is 41.4 J/kg K at the ambient pressure, whereas it is 33 J/kg K at 8.5 kbar. We find that by adjusting the Co concentration and applying suitable pressure, NiCoMnSb system can be tuned to achieve giant magnetocaloric effect spread over a large temperature span around the room temperature, thereby making it a potential magnetic refrigerant material for applications.Comment: 16 pages, 5 figure

Investigation of Complex Impedance and Modulus Properties of Nd Doped 0.5BiFeO3-0.5PbTiO3 Multiferroic Composites

0.5BiNdxFe1-xO3-0.5PbTiO3 (x=0.05, 0.10, 0.15, 0.20) composites were successfully synthesized by a solid state reaction technique. At room temperature X-ray diffraction shows tetragonal structure for all concentrations of Nd doped 0.5BiFeO3-0.5PbTiO3 composites. The nature of Nyquist plot confirms the presence of bulk effects only for all compositions of Nd-doped 0.5BiFeO3-0.5PbTiO3 composites. The bulk resistance is found to decreases with the increasing in temperature as well as Nd concentration and exhibits a typical negative temperature coefficient of resistance (NTCR) behavior. Both the complex impedance and modulus studies have suggested the presence of non-Debye type of relaxation in the materials. Conductivity spectra reveal the presence of hopping mechanism in the electrical transport process of the materials. The activation energy of the composite increases with increasing Nd concentration and were found to be 0.28, 0.27, 0.31 and 0.32eV for x=0.05, 0.10, 0.15, 0.20 respectively at 200-275 oC for conduction process.Comment: 22 pages, 12 figures, 2 tables, 34 Referenc