Tribology of Wire Arc Spray Coatings under the Influence of Regenerative Fuels

In order to further optimize the efficiency of today’s internal combustion engines, specific coatings are used on functional surfaces to reduce internal engine friction and wear. In the current research project, oxymethylene ether (OME) is discussed because it is CO2 neutral and has a strong soot-reducing effect as a fuel or fuel additive. In some operational regimes of the internal combustion engine a dilution of engine oil by fuel must be assumed. In this paper, the frictional contact between piston ring and cylinder raceway is modelled using a pin-on-disk tribometer and the friction and wear behavior between a diamond-like carbon coating (DLC) and a thermal spray coating is characterized. The wear of the spray layer could be continuously detected by radionuclide technology (RNT). With the aid of photoelectron spectroscopic measurements (XPS), the steel thermal spray coating was chemically analyzed before and after the tribometer tests and the oxidative influence of OME was investigated. In addition, confocal microscopy was used to assess the topographies of the specimens. The measurements showed that the addition of OME to the lubricant reduced the viscosity and load-bearing capacity of the lubricating film, which led to an increase in the coefficient of friction. While almost no wear on the pin could be detected at 10% OME, the first visible material removal occurs at an OME content of 20% and the layer delaminated at 30% OME. The evaluation of the RNT wear tests showed that both the tests with engine oil and with engine oil plus 20% OME achieved very low wear rates. No corrosion of the thermal spray coating could be detected by XPS. Only the proportion of engine oil additives in the friction track increased with increasing OME concentration

Einfach zu applizierende 2K-Antihaftbeschichtung für geräuschloses Ablösen von EPDM-Luftdichtungen

Dichtungen müssen grundsätzlich zwei schwer zu vereinenden Ansprüchen gerecht werden. Damit eine maximale Dichtigkeit erreicht wird, muss das Material eine große Flexibilität aufweisen und trotzdem sollte die Dichtung nach längeren Standzeiten sowie mit zunehmender Alterung nicht haften bleiben. Dies ist besonders bei Luftdichtungen, wie sie von der Firma Air-lux bei Schiebefenster eingesetzt werden, sehr wichtig. Allein durch das Formgedächtnis des Materials sollte sich die Luftdichtung zusammenfalten und sich vom Rahmen ablösen [2]. Üblicherweise werden Trennmittel wie Talk oder Silikonöl eingesetzt, um Ablösegeräusche oder komplettes Anhaften zu verhindern. Diese sind aber kaum beständig und müssen regelmäßig frisch aufgetragen werden. In diesem Projekt wurde für EPDM-Fensterdichtungen eine gegen Reinigungsmittel beständige Antihaft-Beschichtung entwickelt. Die 2K-Beschichtung kann direkt nach der Produktion aber auch auf bereits verbauten Dichtungen appliziert werden und so deren Lebensdauer verlängern

Dual-polarized chipless humidity sensor tag

In this letter, a miniaturized, flexible and high data dense dual-polarized chipless radio frequency identification (RFID) tag is presented. The tag is designed within a minuscule footprint of 29 × 29 mm2 and has the ability to encode 38-bit data. The tag is analyzed for flexible substrates including Kapton® HN DuPont™ and HP photopaper. The humidity sensing phenomenon is demonstrated by mapping the tag design, using silver nano-particle based conductive ink on HP photopaper substrate. It is observed that with the increasing moisture, the humidity sensing behavior is exhibited in RF range of 4.1–17.76 GHz. The low-cost, bendable and directly printable humidity sensor tag can be deployed in a number of intelligent tracking applications

Electric field tunable superconductor-semiconductor coupling in Majorana nanowires

We study the effect of external electric fields on superconductor-semiconductor coupling by measuring the electron transport in InSb semiconductor nanowires coupled to an epitaxially grown Al superconductor. We find that the gate voltage induced electric fields can greatly modify the coupling strength, which has consequences for the proximity induced superconducting gap, effective g-factor, and spin-orbit coupling, which all play a key role in understanding Majorana physics. We further show that level repulsion due to spin-orbit coupling in a finite size system can lead to seemingly stable zero bias conductance peaks, which mimic the behavior of Majorana zero modes. Our results improve the understanding of realistic Majorana nanowire systems.Comment: 10 pages, 5 figures, supplemental information as ancillary fil

A Tale of Two Stories from "Below the Line": Comment Fields at the Guardian

This article analyzes the nature of debate on “below the line” comment fields at the United Kingdom’s Guardian, and how, if at all, such debates are impacting journalism practice. The article combines a content analysis of 3,792 comments across eighty-five articles that focused on the UN Climate Change Summit, with ten interviews with journalists, two with affiliated commentators, plus the community manager. The results suggest a more positive picture than has been found by many existing studies: Debates were often deliberative in nature, and journalists reported that it was positively impacting their practice in several ways, including providing new story leads and enhanced critical reflection. However, citizen–journalist debate was limited. The results are attributed to the normalization of comment fields into everyday journalism practice, extensive support and encouragement from senior management, and a realization that comment fields can actually make the journalists’ life a little easier