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.

PVDF-PZT Composite Films for Transducer Applications.

Abstract: Piezoelectric polymer-ceramic composites are promising materials for transducer applications. PVDF-PZT composite films have been developed with different weight fraction and particle size of PZT using a solvent cast method. Films are investigated using X-ray diffraction technique, scanning electron microscopy, Fourier transformed infrared spectroscopy, and differential scanning calorimetry to study crystal structural changes, distribution of particles within the polymer matrix, the influence of these particles at the molecular level, and the changes induced in the melting transition and in the degree of crystallinity of the composites, respectively. The variation in these properties as a function of weight fraction (10–50%) and particle size (1 μm and ∼25 μm) of PZT has also been investigated. The composite films are tested for their application as acoustic emission (AE) sensor.

Characterization of Mechanical Behavior of Metallic and Non-metallic Particulate Filled Epoxy Matrix Composites

Abstract: Studies were carried out on RT cure epoxy (LY556 þ HY951) composite system comprised of metallic and non-metallic fillers. The results of the studies carried out on composites with three distinctly different particulate fillers, representing ductile (Cu and Al), brittle (SiC), and soft (Gr) type of materials regarding the mechanical properties, showed that the tensile and flexural strength of the particulate composites degraded with filler loading, whereas the modulus (both tensile and flexural) of the composites increased with the filler loading for the range of filler contents considered (10-40 wt%). The compression strength of all the composites increased to a maximum up to a filler loading of 30% and then decreased beyond this value, with the SiC-Ep composites exhibiting the highest improvement in the compression strength.

Studies on Mechanical Behavior of Microwave and Thermally Cured Glass Fiber Reinforced Polymer Composites

Abstract: An investigation into the mechanical behavior of microwave-cured glass-epoxy composites is carried out and the results are compared with those of thermally cured composites. Microwave curing of a glass fiber reinforced bifunctional epoxy resin system (LY556/HY951) is carried out in custom-built, multi-mode, industrial microwave cure equipment operating at a frequency of 2450 MHz. Through tensile, compression, and flexural strength tests, it is demonstrated that while the mechanical properties of microwave-cured composites compare well with those of the thermally cured ones, the microwave curing process, per se, results in a significant reduction in the process cycle time and power consumption.

Influence of codeposition of copper on the structure and morphology of electroless Ni–W–P alloys from sulphate- and chloride-based baths

Abstract: Quaternary Ni–W–Cu–P coatings were deposited by using alkaline-citrate-based nickel sulphate and nickel chloride baths. The structure and morphology of these deposits are reported for the first time and compared with ternary Ni–W–P deposits from the same baths without copper addition. Incorporation of copper has marginal influence on the nickel, phosphorus and tungsten contents of the coatings. Increase in grain size with the incorporation of copper was found in B1-based coatings, but in the case of B2 coatings, no change is observed. In case of ternary deposits, morphology of B1-based coatings was coarse, and nodular, whereas that of B2-based coatings were smoother. Addition of copper in both B1 and B2 coatings had resulted in very smooth nodular-free deposits. XPS studies showed that addition of copper increases the elemental form of W in the chloride-based deposits towards that of sulphate-based deposits. Copper has no detrimental effect on the hardness but improves the surface quality.