11,887 research outputs found
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
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
Star Clusters in the Magellanic Clouds-1: Parameterisation and Classification of 1072 Clusters in the LMC
We have introduced a semi-automated quantitative method to estimate the age
and reddening of 1072 star clusters in the Large Magellanic Cloud (LMC) using
the Optical Gravitational Lensing Experiment (OGLE) III survey data. This study
brings out 308 newly parameterised clusters. In a first of its kind, the LMC
clusters are classified into groups based on richness/mass as very poor, poor,
moderate and rich clusters, similar to the classification scheme of open
clusters in the Galaxy. A major cluster formation episode is found to happen at
125 +- 25 Myr in the inner LMC. The bar region of the LMC appears prominently
in the age range 60 - 250 Myr and is found to have a relatively higher
concentration of poor and moderate clusters. The eastern and the western ends
of the bar are found to form clusters initially, which later propagates to the
central part. We demonstrate that there is a significant difference in the
distribution of clusters as a function of mass, using a movie based on the
propagation (in space and time) of cluster formation in various groups. The
importance of including the low mass clusters in the cluster formation history
is demonstrated. The catalog with parameters, classification, and cleaned and
isochrone fitted CMDs of 1072 clusters, which are available as online material,
can be further used to understand the hierarchical formation of clusters in
selected regions of the LMC.Comment: 19 pages, 19figures, published in MNRAS on August 16, 2016
Supplementary material is available in the MNRAS websit
Heusler 4.0: Tunable Materials
Heusler compounds are a large family of binary, ternary and quaternary
compounds that exhibit a wide range of properties of both fundamental and
potential technological interest. The extensive tunability of the Heusler
compounds through chemical substitutions and structural motifs makes the family
especially interesting. In this article we highlight recent major developments
in the field of Heusler compounds and put these in the historical context. The
evolution of the Heusler compounds can be described by four major periods of
research. In the latest period, Heusler 4.0 has led to the observation of a
variety of properties derived from topology that includes: topological metals
with Weyl and Dirac points; a variety of non-collinear spin textures including
the very recent observation of skyrmions at room temperature; and giant
anomalous Hall effects in antiferromagnetic Heuslers with triangular magnetic
structures. Here we give a comprehensive overview of these major achievements
and set research into Heusler materials within the context of recent emerging
trends in condensed matter physics
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