It poses great problems to our society, making it the subject of investigation for many research groups, which dedicate great efforts to find means to prevent or control this process. The Universidad Autónoma de Madrid has tested a new protection technique that consists of the electrodeposition of a conductive polymer (polypyrrole) over the surface of a material like copper that is easily oxidised.
Copper is widely used for many applications and being a metal that oxidises relatively easily, its conservation represents a great economical benefit. Conventional methods to avoid or minimise corrosion of the material are in many cases short lived, very expensive and involve the use of toxic chemicals.
A recent article by Pilar Herrasti published in the Electrochimica Acta journal describes how copper has been successfully covered with a conductive polymer that creates a barrier with the corrosive environment while leaving the conductive property of the material untouched. Conductive polymers are remarkable materials - plastics with a slightly altered composition that make them capable of conducting electricity. Synthesising these polymers is not complicated and the process can be varied to increase or decrease their conductivity.
When an oxidising potential is applied to a pyrrole solution, it oxidises the compound over the electrode, and a thin film of the material is laid over the metal. In the case of copper, the methodology involves generating a layer of copper oxide over which the polymer is deposited. This layer is conductive like the metal and since it is deposited in an oxidised state it can then be reduced, maintaining the copper in the passivity zone (non corrosion zone), while simultaneously acting as a physical barrier between the copper and the environment. For its effect to be adequate on the material there are two fundamental conditions, the oxide-reductive potential must be high and there should be minimal porosity.
To achieve this goal, a detailed study of electrodeposition has been carried out, using different techniques, and adjusting the different parameters such as environmental composition and potentials or currents applied. The polymer deposited copper was then tested by submerging it in a solution of NaCl, simulating sea water, which is one of the most corrosive environments there are, since it contains large numbers of chloride ions.
These ions are responsible for an extremely localised form of corrosion that leads to the creation of small holes in the metal, known as pitting. The study of the behaviour of these materials had led to the conclusion that by tuning the different parameters, a thin film can be created that withstands the attack of this harsh environment for at least a month.
New biomaterial could replace plastic laminates, greatly reduce pollution
21.09.2017 | Penn State
Stopping problem ice -- by cracking it
21.09.2017 | Norwegian University of Science and Technology
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
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22.09.2017 | Physics and Astronomy