The design of new materials with two or more functional groups must be strongly considered to achieve multifunctional coatings with outstanding properties such as active−passive protection against corrosion, low-friction, antifouling, and sensing, among others. In this sense, nanocomposites based on solvent-free epoxy resin/bifunctionalized reduced graphene oxide layers with NH 2 and NH 3 + groups (ER/BFRGO) with super-anticorrosive properties are for the first time reported here. The amine groups (−NH 2 ) act as cross-linker agents, which react with epoxy terminal groups from resin, thus closing the gap between the BFRGO layers and the polymeric matrix. Meanwhile, the ammonium ions (−NH 3 + ) are effective trapping agents of negatively charged atoms or molecules (e.g., Cl − ). This novel combination enables us to obtain nanocomposite coatings with passive−active protection against corrosion. ER/BFRGO deposited onto A36 mild steel exhibited a remarkably enhanced barrier against corrosion into a saline medium (1 M NaCl; 58.4 g/L), wherein the corrosion current density (i corr ) was diminished 6 orders of magnitude (i corr = 5.12 × 10 −12 A/ cm 2 ), with respect to A36 mild steel coated only with ER (i corr = 2.34 × 10 −6 A/cm 2 ). Also, the highest polarization resistance R p = 6.04 × 10 7 Ω/cm 2 was obtained, which represents the lowest corrosion rate and corresponds to 3 orders of magnitude higher than A36 mild steel coated with ER (R p = 1.43 × 10 4 Ω/cm 2 ). The strategy of bifunctionalization proposed herein to obtain bifunctionalized reduced GO with NH 2 and NH 3 + groups has not been disclosed in the literature before; in consequence, this work opens a new pathway toward the design of smart materials based on multifunctional nanomaterials.
The use of Ground Source Heat Pumps (GSHPs) has grown exponentially around the world over recent decades. The GSHP represents an alternative device to electric heating systems and oil boilers. Additionally, it requires a lower power consumption and less maintenance than combustion-based heating systems. Moreover, the CO2 emissions produced by a GSHP are lower than other systems based on burning oil, gas, or biomass. However, the main obstacle for the widespread use of GSHPs is the high cost of Ground Heat Exchanger (GHE) installation, a technology that exhibits low thermodynamic efficiencies. Over the past decade, some studies have been conducted to improve heat transfer in GHE pipes using traditional working fluids, creating new pipe materials or designing new heat exchanger configurations. The main contribution of this paper is a summarization of the outcomes of theoretical, numerical and experimental studies to improve heat transfer in GHEs using nanotechnology. Additionally, the development of new fluids (nanofluids) and new materials (nanoparticles and nanocomposites) applied to heat exchanger pipes and the designs and configurations of GHEs are highlighted. As a result, the present review provides a perspective for future research regarding the use of nanotechnology to reduce the costs involved in GHE for GSHP improvement.
A computational study was carried out in order to verify the assumption of reducing the magnitudes of electrical stresses generated in standard suspension-type disc insulators energized with high voltage alternating current (JIVAC), by including a semiconducting insert within their geometry. As a consequence, an improved performance of these insulators was expected during flashover tests in polluted conditions. Grading of stresses in the region adjacent to the pin of insulators is the factor responsible for such improved performance. These computational and experimental results were compared to those obtained from similar calculations and tests, but considering conventional non-modified insulators. Two different conductivity characteristics of the semiconducting insert were considered during the simullations. Then, an electrical evaluation of the above referred alternatives, as well as an additional set of alternatives was also develolped in a clean fog chamber. Results from computational studies showed decreases in the maximum stress found in the test arrangement ranging from 29% up to 45%, with respect to those corresponding to the base case (conventional insulators). These values are in a reasonably good agreement with increases achieved in the flashover voltage of the corresponding alternatives, when evaluated in the clean fog chamber. Increases in the flashover voltage resulted 33% and 44 % for each simulated case, respectively. For every alternative evaluated, an increase in the corresponding flashover voltage was always achieved. In the worst case, a 12% increase was obtained; for the best case, an increaase even higher than 97% was found.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.