Bioinspired Stimuli‐Responsive and Antifreeze‐Secreting Anti‐Icing Coatings

The detrimental impacts of icing on transportation and power industries are well‐known. Inspired by natural systems that secrete a functional liquid in response to stimuli, this work introduces an anti‐icing coating that responds to surface icing by releasing antifreeze liquid. It consists of an outer porous superhydrophobic epidermis and a wick‐like underlying dermis that is infused with antifreeze liquid. The functionality of the new coating is validated through condensation frosting, simulated freezing fog, and freezing rain experiments. In the tested conditions, the introduced anti‐icing skin delays onset of frost, rime, and glaze accumulation at least ten times longer than anti‐icing superhydrophobic and lubricant impregnated surfaces. Furthermore, the coating delays onset of glaze formation ten times longer than surfaces flooded with a thin film of antifreeze. In each of the icing scenarios, the fundamental mechanisms responsible for antifreeze release and their relation to required antifreeze replenishment rates are described.     

Bioinspired Surfaces with Superwettability for Anti‐Icing and Ice‐Phobic Application: Concept,Mechanism, and Design

Ice accumulation poses a series of severe issues in daily life. Inspired by the nature, superwettability surfaces have attracted great interests from fundamental research to anti‐icing and ice‐phobic applications. Here, recently published literature about the mechanism of ice prevention is reviewed, with a focus on the anti‐icing and ice‐phobic mechanisms, encompassing the behavior of condensate microdrops on the surface, wetting, ice nucleation, and freezing. Then, a detailed account of the innovative fabrication and fundamental research of anti‐icing materials with special wettability is summarized with a focus on recent progresses including low‐surface energy coatings and liquid‐infused layered coatings. Finally, special attention is paid to a discussion about advantages and disadvantages of the technologies, as well as factors that affect the anti‐icing and ice‐phobic efficiency. Outlooks and the challenges for future development of the anti‐icing and ice‐phobic technology are presented and discussed.     

Easy‐to‐clean Schichten – spezielle Anwendungen

Easy to clean surfaces – special applications Easy to clean surfaces can be made by wet‐chemical coating with subsequent heat‐treatment. Organically modified metal oxide films form the base reinforced by nano composite structures. The hydro‐ and oleophobic effect is obtained by perfluorinated organic molecule chains in the nano composite sol‐gel coatings. Application specific materials can be synthesized by the proper choice of suitable starting compounds and process parameters. The resulting coatings consist of a three‐dimensional cross‐linked inorganic part (such as a silica network) combined with an organic part. The organic material acts either as a surface modifier (example: alkyl, phenyl) or as crosslinker (example: acrylic, epoxy). The properties of such coating systems can be adjusted to obtain a wide range of glass‐ceramic or polymer‐like properties. The incorporation of nanoparticles into these materials significantly enhances the abrasion and the scratch resistance. Such coatings mainly on metal parts are used in diagnostics, analytical chemistry and medical technology.     

Nanocomposite‐Beschichtungen auf CBN‐Werkzeugen

Nanocomposite coatings on CBN‐tools CBN (cubic boron nitride) cutting materials are often used to improve the properties of cutting tools. This allows new applications and processes, which are not possible with common cutting materials (e.g. hard metals). Today CBN cutting materials are mostly coated to estimate the wear by an optical evaluation. Coatings on CBN cutting materials for enhancement of the tribological properties are normally not used. For improvement of the properties of used CBN tools during the cutting process a coating technology was developed. This technology combines the advantages of CBN cutting materials with the excellent properties (e.g. hardness, temperature stability) of nanostructured materials. Investigations with different coating systems and pre‐treatment processes were done to test the CBN cutting tools. These investigations have been shown, that nanocomposite coatings can be used to enhance the tool life of CBN cutting tools. Important for an increase in the tool life is a very good coating adhesion, which can be reached by special adhesion layers and an optimized coating structure.     

Anti‐Icing Superhydrophobic Surfaces Based on Core‐Shell Fossil Particles

A novel approach for the design of functional coatings using fossil diatomaceous earth particles decorated by a thin layer of grafted polymer chains is reported. The polymer‐modified diatomaceous earth particles are able to form liquid marbles, superhydrophobic surfaces, and are highly promising for the design of anti‐icing coatings.     

Rolling contact fatigue mechanism of a plasma‐sprayed and laser‐remelted Ni alloy coating

The rolling contact fatigue behaviour of the plasma‐sprayed and laser‐remelted Ni‐Cr‐B‐Si alloy coatings under two different tribological conditions of contact pressure was investigated. Two sets of fatigue‐life data of coatings were characterized by Weibull distributions. The failure mode of the coatings was identified on the basis of worn morphologies as observed at the surfaces of the failed coatings. The tribological mechanism leading to the formation of the fatigue spall was discussed on the basis of the subsurface morphologies observed in the failed coating. Experimental results showed that, the mean life and characteristic life of the coating decreased with increasing the contact pressure. The failure of the coatings can be termed as spalling‐type failure. A refined ‘ring‐crack model' was proposed to explain the formation of the fatigue spall. In the refined model, it was postulated that the joining of the ring‐type cracks and subsurface branched cracks was directly responsible for the spall formation.     

Korrosionsinhibierende Plasmapolymerschichten auf Stahluntergründen

Plasma polymeric coatings with inhibitory effect on steel surfaces The plasma based surface technique facilitates scientifically and technically, economically and ecologically interesting alternatives to traditional treatment procedures. From that the evolution of a new procedure for the improvement of the corrosion resistance of low‐alloy steel surfaces through ultrathin plasma polymeric coatings was a main topic at the iLF in the last years. After plasma based super cleaning process under oxidized conditions should be produced plasma polymeric coatings with a corrosion inhibiting / passivation effect. For this purpose corrosion inhibitor molecules are implanted into the normally electrochemically inactive coating during the process of the plasma based polymerization of silicon‐organic monomers. Through that it has been proved that the long‐term corrosion protection improves. Besides the surface of the produced plasma polymer shift can be modified by plasma‐technical procedures so that it shows also optimal adhesion promoter characteristics.     

Entwicklung hochverschleißbeständiger wolframschmelzkarbidbasierter Schichten auf Aluminiumbauteilen durch Plasma‐Pulver‐Auftragschweißen

Development of high wear‐resistant FTC‐based coatings on aluminium components using plasma transferred arc welding Nowadays, functional surfaces of components can be effectively protected from extreme wear with the help of fused tungsten carbide (FTC) coatings. The wear protection of steel components using FTC has been well known for many years. This paper presents the feasible study of improving the wear resistance of aluminium components with FTC particles using plasma powder arc welding. The FTC coatings are developed with two methods: one is the dispersion of carbide particles in aluminium and the other one is the combination of dispersing and alloying of FTC‐based composite powders. In this research, coatings within a thickness range of a few millimeters are developed with varying process parameters and compositions of the filler materials. The developed coating systems are tested with regard to their specific properties and their wear resistance. Finally, their application potential is presented.     

Single‐layer and multi‐layer wear‐resistant coatings

In this paper the formation of wear‐resistant coatings based on titanium and aluminum compounds using vacuum arc discharge and molecular nitrogen as a working gas is discussed. The experiments were carried out using an installation containing two independent evaporators and a system for attenuation and purification of the plasma flow. To obtain a high‐quality coating, it is necessary to ensure the equality of the ion flux densities coming to the substrate. The results of the experiments show that by changing the bias voltage on the substrate it is possible to adjust the content of elements in the coating and thus to control its parameters. Multi‐layer coatings have better performance characteristics, but require an improved degree of purification of the plasma flow from the droplet fraction.     

Mikrowellen‐PECVD für kontinuierliche Großflächenbeschichtung bei Atmosphärendruck

Microwave PECVD for continuous wide area coating at atmospheric pressure Plasma processes are applied for a variety of surface modifications. Examples are coatings to achieve an improved corrosion and scratch protection, or surface cleaning. Normally, these processes are vacuum based and therefore suitable to only a limited extend for large area industrial applications. By use of atmospheric pressure plasma technology integration in continuously working manufacturing lines is advantageously combined with lower costs and higher throughput. Microwave plasma sources present powerful modules for plasma enhanced chemical vapour deposition at atmospheric pressure. At Fraunhofer IWS processes and equipment as well as application specific materials are developed. The coatings are suitable for scratch resistant surfaces, barrier and corrosion protective layers or anti‐reflex layers on solar cells. The film properties achieved are comparable with those produced by low pressure processes.     

Excellent Anti‐Icing Abilities of Optimal Micropillar Arrays with Nanohairs

Anti‐icing abilities are achieved on surfaces of micropillar arrays with nanohairs that are fabricated by methods of soft replication and crystal growth, i.e., different micropillar arrays with the similar nanohairs, different nanohairs with the same micropillar arrays. It is demonstrated that an optimal micropillar array with nanohairs contributes an excellent anti‐icing or antifogging property at low temperature below zero. As a result, the longest icing delay time is achieved effectively up to ≈9839 s at −10 °C on the optimal surface. As for the optimal surface in humidity, the condensed droplets merge into each other, and meanwhile jump off easily. Accordingly, a largest dry area is up to ≈90.5% at −5 °C in ≈1020 s after breeze action. It is attributed to the stability of less liquid–solid fraction on an optimal surface under low temperature, in addition to cooperation between micropillar arrays and nanohairs in sizes. This finding provides an insight into the design of structure size on micro–nanostructured surface for anti‐icing/antifogging ability effectively, which can be extended into the applications in some surfaces of systems, e.g., microdevices worked in cold or humid environment.     

Hybrid Copper‐Nanowire–Reduced‐Graphene‐Oxide Coatings: A “Green Solution” Toward Highly Transparent,Highly Conductive,and Flexible Electrodes for (Opto)Electronics

This study reports a novel green chemistry approach to assemble copper‐nanowires/reduced‐graphene‐oxide hybrid coatings onto inorganic and organic supports. Such films are robust and combine sheet resistances (<30 Ω sq^?1) and transparencies in the visible region (transmittance > 70%) that are rivalling those of indium–tin oxide. These electrodes are suitable for flexible electronic applications as they show a sheet resistance change of <4% after 10 000 bending cycles at a bending radius of 1.0 cm, when supported on polyethylene terephthalate foils. Significantly, the wet‐chemistry method involves the preparation of dispersions in environmentally friendly solvents and avoids the use of harmful reagents. Such inks are processed at room temperature on a wide variety of surfaces by spray coating. As a proof‐of‐concept, this study demonstrates the successful use of such coatings as electrodes in high‐performance electrochromic devices. The robustness of the electrodes is demonstrated by performing several tens of thousands of cycles of device operation. These unique conducting coatings hold potential for being exploited as transparent electrodes in numerous optoelectronic applications such as solar cells, light‐emitting diodes, and displays.     

热喷涂纳米结构涂层技术的研究进展

与传统材料的热喷涂涂层相比,纳米结构涂层在力学和摩擦学等方面的性能有了一定的提高.作者综述了国内外在应用热喷涂技术制备纳米结构涂层方面的研究进展.介绍了纳米结构喂料的制备、热喷涂纳米结构涂层的构筑方法、涂层的特殊性能以及应用情况.从目前国内外的情况来看,热喷涂纳米结构涂层技术的研究取得了较大的进展.随着技术、工艺的不断完善,其必将在很多领域取代传统的涂层.     

Neuartige dekorative Farbschichten durch Plasma‐Beschichtung

Novel decorative color coatings using plasma deposition The market does not stop to demand for novel products. Only those who offer innovative products will explore new segments of the market and will not loose against the cheap suppliers from far eastern countries. This is even more important in the field of surface technology. Many products would not be competitive without plasma technology. Companies changing surfaces with plasma technology expect a noticeable growth between 20 and 50 % within the next years [1]. The deposition of thin layers using plasma makes it possible to obtain highly brilliant color coatings, specially mixed color effects (rainbow like) as well as color changes depending of the observation angle. These optical special effects would not be feasible with common painting techniques. Thus plasma deposition opens a new field for surface coating. In these layers the colors are created via interference effects of the light being used for illumination. They are called interference colors, well known to the most of us from thin oil films on a wet street.     

Multi‐Modal,Surface‐Focused Anticoagulation Using Poly‐2‐methoxyethylacrylate Polymer Grafts and Surface Nitric Oxide Release

This study examines platelet adhesion on surfaces that combine coatings to limit protein adsorption along with “anti‐platelet” nitric oxide (NO) release. Uncoated and poly‐2‐methoxyethylacrylate (PMEA) coated, gas permeable polypropylene (PP) membranes were placed in a bioreactor to separate plasma and gas flows. Nitrogen with 100/500/1000 ppm of NO was supplied to the gas side as a proof of concept. On the plasma side, platelet rich plasma (PRP, 1 × 108 cell/mL) was recirculated at low (60)/high (300) flows (mL/min). After 8 hours, adsorbed platelets on PP was quantified via a lactate dehydrogenase assay. Compared to plain PP, the PMEA coating alone reduced adsorption by 17.4 ± 9.2% and 29.6 ± 16.6% at low and high flow (p < 0.05), respectively. NO was more effective at low plasma flow. At 100 and 500 ppm of NO, adsorption fell by 37.9 ± 6.1% and 100 ± 4.7%, (p < 0.001), on plain PP. At high flow with 100, 500, and 1000 ppm of NO, adsorption reduced by 17.9 ± 17.8%, 46.4 ± 23.2%, and 100 ± 4.8%, (p < 0.001), respectively. On PMEA‐coated PP with only 100 ppm, adsorption fell by 69.7 ± 6.8 and 65.6% ± 16.9%, (p < 0.001), at low and high flows respectively. Therefore, the combination of an anti‐adsorptive coating with NO has great potential to reduce platelet adhesion and coagulation at biomaterial surfaces.     

Superhydrophobic Coatings on Cellulose‐Based Materials: Fabrication,Properties, and Applications

Wettability of a solid surface by a liquid plays an important role in several phenomena and applications, for example in adhesion, printing, and self‐cleaning. In particular, wetting of rough surfaces has attracted great scientific interest in recent decades. Superhydrophobic surfaces, which possess extraordinary water repelling properties due to their low surface energy and specific nanometer‐ and micrometer‐scale roughness, are of particular interest due to the great variety of potential applications ranging from self‐cleaning surfaces to microfluidic devices. In recent years, the potential of superhydrophobic cellulose‐based materials in the function of smart devices and functional clothing has been recognized, and in the past few years cellulose‐based materials have established themselves among the most frequently used substrates for superhydrophobic coatings. In this Review, over 40 different approaches to fabricate superhydrophobic coatings on cellulose‐based materials are discussed in detail. In addition to the anti‐wetting properties of the coatings, particular attention is paid to coating durability and other incorporated functionalities such as gas permeability, transparency, UV‐shielding, photoactivity, and self‐healing properties. Potential applications for the superhydrophobic cellulose‐based materials range from water‐ and stain‐repellent, self‐cleaning and breathable clothing to cheap and disposable lab‐on‐a‐chip devices made from renewable sources with reduced material consumption.     

Lubricant‐Infused PET Grafts with Built‐In Biofunctional Nanoprobes Attenuate Thrombin Generation and Promote Targeted Binding of Cells

New surface coatings that enhance hemocompatibility and biofunctionality of synthetic vascular grafts such as expanded poly(tetrafluoroethylene) (ePTFE) and poly(ethylene terephthalate) (PET) are urgently needed. Lubricant‐infused surfaces prevent nontargeted adhesion and enhance the biocompatibility of blood‐contacting surfaces. However, limited success has been made in incorporating biofunctionality onto these surfaces and generating biofunctional lubricant‐infused coatings that both prevent nonspecific adhesion and enhance targeted binding of biomolecules remains a challenge. Here, a new generation of fluorosilanized lubricant‐infused PET surfaces with built‐in biofunctional nanoprobes is reported. These surfaces are synthesized by starting with a self‐assembled monolayer of fluorosilane that is partially etched using plasma modification technique, thereby creating a hydroxyl‐terminated fluorosilanized PET surface. Simultaneously, silanized nanoprobes are produced by amino‐silanizing anti‐CD34 antibody in solution and directly coupling the anti‐CD34‐aminosilane nanoprobes onto the hydroxyl terminated, fluorosilanized PET surface. The PET surfaces are then lubricated, creating fluorosilanized biofunctional lubricant‐infused PET substrates. Compared with unmodified PET surfaces, the designed biofunctional lubricant‐infused PET surfaces significantly attenuate thrombin generation and blood clot formation and promote targeted binding of endothelial cells from human whole blood.     

PVD‐Schutzschichten für Werkzeuge des Präzisionsblankpressens

PVD protective coatings for precision molding tools Precision glass molding (PGM) is a replicative hot forming process for the production of complex optical components, such as aspherical lenses for digital and mobile phone cameras or optical elements for laser systems. The efficiency and thus also the profitability of the PGM depend on the unit price per pressed component, which correlates primarily with the service lifetime of the pressing tools. To increase tool lifetime, the tool surfaces are coated with protective coatings based on precious metals or carbon using physical vapour deposition (PVD). The PVD coating technology enables the deposition of thin coatings, which also follow more complex surface geometries and achieve a high surface quality. PVD coatings are also commonly used to protect tools from wear and corrosion. This paper presents two chromium‐based nitride hard coatings produced by an industrial PVD unit and investigated for their applicability for PGM. Two different coating architectures were implemented, on the one hand a single coating chromium aluminium nitride (Cr,Al)N coating and on the other hand a nanolaminar CrN/AlN coating with alternating layers of chromium nitride and aluminium nitride. The latter is a coating consisting of hundreds of nano‐layers, only a few nanometers thick. Both coatings, (Cr,Al)N and CrN/AlN, each have a thickness of s ～ 300 nm in order to follow the tool contour as closely as possible. The properties of the coating systems, which are of particular relevance for PGM, are considered. These include on the one hand the adhesion of glass, the roughness and topography of the surface and the adhesion between the coating and the tool material. In addition, the barrier effect of the coatings against diffusion of oxygen was investigated. In order to reproduce the thermal boundary conditions of the PGM, thermocyclic aging tests are performed and their influence on the different properties is described.     

Facile Plasma‐Enhanced Deposition of Ultrathin Crosslinked Amino Acid Films for Conformal Biometallization

A novel method for the facile fabrication of conformal, ultrathin, and uniform synthetic amino acid coatings on a variety of practical surfaces by plasma‐enhanced chemical vapor deposition is introduced. Tyrosine, which is utilized as an agent to reduce gold nanoparticles from solution, is sublimed into the plasma field and directly deposited on a variety of substrates to form a homogeneous, conformal, and robust polyamino acid coating in a one‐step, solvent‐free process. This approach is applicable to many practical surfaces and allows surface‐induced biometallization while avoiding multiple wet‐chemistry treatments that can damage many soft materials. Moreover, by placing a mask over the substrate during deposition, the tyrosine coating can be micropatterned. Upon its exposure to a solution of gold chloride, a network of gold nanoparticles forms on the surface, replicating the initial micropattern. This method of templated biometallization is adaptable to a variety of practical inorganic and organic substrates, such as silicon, glass, nitrocellulose, polystyrene, polydimethylsiloxane, polytetrafluoroethylene, polyethylene, and woven silk fibers. No special pretreatment is necessary, and the technique results in a rapid, conformal amino acid coating that can be utilized for further biometallization.     

Anorganisch‐organische Hybridschichten für die Entspiegelung optischer Oberflächen

Inorganic‐organic hybrid coatings for antireflection of optical surfaces The application of nanostructures for optical surfaces has been discussed since antireflective nanostructures have been discovered on the eyes of night‐flying insects. On injection molded plastic lenses, antireflective nanostructures can easily be produced by plasma etching. The procedure has now been adapted to vacuum evaporated organic layers. Complex coatings composed of inorganic layers and organic nanostructures are especially suitable for realizing broadband antireflection properties on glass lenses.