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.

EIS and XPS studies on the self-healing properties of Ce-modified silica-alumina hybrid coatings: Evidence for Ce(III) migration

Abstract: Cerium nitrate added silica-alumina hybrid sol-gel coatings have been explored for the corrosion protection of AA2024-T3. The self-healing property of the coating is investigated experimentally by electrochemical impedance spectroscopy and exfoliation test. The results confirm that coatings containing 0.005 M cerium nitrate inhibitor offers superior protection to the surface. Increase in the surface concentration of Ce species in the corrosion tested coating, as evaluated from X-ray photoelectron spectroscopy (XPS) studies, provides a strong evidence for the outward migration of cerium ions from the coating. Improved corrosion protection observed is attributed to the combined effect of the stable barrier nature of the coating and the corrosion inhibiting nature of Ce3 + ions.

Effect of strain on the thermomechanical behavior of epoxy based shape memory polymers

Abstract: The effect of deformation strain on the thermomechanical (TM) behavior of a commercially available bifunctional epoxy resin modified with 5 % carboxyl-terminated butadiene acrylonitrile (CTBN) was studied. The results were compared with those for the unmodified epoxy SMP. The glass transition temperatures (T g) as well as the moduli of these SMPs were determined. Static tensile tests were carried out at both 25 °C and 115 °C to study the effect of CTBN addition on the failure strain. TM cycling tests were conducted for two prescribed strain values: 15 % and 25 %. Further, the effect of the prescribed strain values and TM cycling on the shape-frozen and recovery responses of these SMPs were studied. In addition, microstructure studies were carried out in order to examine the dispersion of the CTBN and the fracture behavior of the CTBN-epoxy SMP. The results show that adding CTBN to the epoxy matrix leads to a slight reduction in storage modulus and T g. Static tensile tests revealed that there was a noticeable improvement in the failure strain of the CTBN-epoxy SMP when it was tested at 115 °C rather than at 25 °C. The cyclic thermomechanical tests performed here prove that the CTBN-epoxy SMP has a better endurance than the unmodified epoxy SMP, as well as enhanced shape-recovery characteristics.