National Aerospace Laboratories

About: National Aerospace Laboratories is a facility organization based out in Bengaluru, India. It is known for research contribution in the topics: Coating & Corrosion. The organization has 1838 authors who have published 2349 publications receiving 36888 citations.

An experimental investigation on the machining characteristics of Nimonic 75 using uncoated and TiAlN coated tungsten carbide micro-end mills

Abstract: We report the machining characteristics and machinability of a nickel based superalloy in this study. A micro-milling operation is loaded on Nimonic 75 using uncoated and TiAlN coated tungsten carbide micro-end mills. A full factorial design of experiments was devised to optimize the machining conditions to reduce the flank wear on the tool surface. The optimized machining conditions for uncoated micro-tools were found to be a cutting speed ( v c ) of 13 m/min and a feed rate ( f z ) of 6 mm/min. Following this, the tools were coated with TiAlN using a semi-industrial four-cathode reactive pulsed direct current unbalanced magnetron sputtering system. Further experiments were then performed using these optimized machining conditions using both uncoated and TiAlN coated micro-tools in order to ascertain the tool wear and surface integrity. The change in geometry of the machined slot was estimated based on the variation in tool radius of the micro-end mill with progression of the operation. A direct comparison was made between the results observed using both uncoated and TiAlN coated tungsten carbide to illustrate the effect of the nanocomposite TiAlN coating. It was seen that TiAlN coated micro-tools exhibited a superior performance as compared to the uncoated ones with respect to tool life and micro-burr formation.

Anchored palladium nanoparticles onto single walled carbon nanotubes: Efficient recyclable catalyst for N-containing heterocycles

Abstract: A convenient process has been developed to decorate palladium nanoparticles onto carboxylic acid functionalized single walled carbon nanotubes (SWNTs) via the thermolysis of palladium acetate. This single walled carbon nanotube–palladium nanoparticles (SWNT–PdNPs) composite has been investigated through a number of instrumental techniques such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM), UV-vis-NIR spectroscopy, resonance Raman spectroscopy and X-ray photoelectron spectroscopy (XPS), which disclose that the palladium nanoparticles are attached by carboxylic acid groups onto the surface of SWNTs. The SWNT–PdNPs composite has been tested as an efficient heterogeneous nanocatalytic system for copper free acyl Sonogashira reaction. A library of ynones was synthesized in high yields under mild reaction condition. The catalyst was recovered and recycled successfully up to seven times. This simple protocol was further broadened in the synthesis of trimethylsilyl-ynones (TMS-ynones) and explored in the one-pot multicomponent synthesis of 2,4-disubstituted pyrimidines.

Optical oxygen sensor coating based on the fluorescence quenching of a new pyrene derivative

Abstract: A new pyrene derivative 1-decyl-4-(1-pyrenyl) butanoate (DPB) was synthesized by the esterification reaction of 1-pyrene butyric acid with n-decanol. The photophysical properties of this pyrene ester were studied in toluene and in silicone polymers. The emission spectra of DPB exhibited excimer emission in solution and in silicone polymer coatings and the emission was effectively quenched by oxygen. A comparison of the oxygen sensor performance of DPB was made with that of pyrene and 1-pyrene butyric acid in silicone polymer coatings. The effect of different silicone resins on the properties of the DPB-based oxygen sensor coating was studied and the most suitable binder was selected. The new pyrene derivative was found to have potential as a substitute for pyrene in pressure-sensitive paints used for the measurement of surface pressure distribution on wind tunnel models.