Recent research efforts to combat marine biofouling have focused on foul-release coatings that are not harmful for the marine environment. Inspired by nature, Slippery Lubricant Infused Porous Surfaces (SLIPS) is a surface modification technology platform with excellent anti-adhesive and antifouling capacities. Pre-commercial coatings based on the SLIPS concept have demonstrated promising results as an environmentally friendly strategy to combat marine biofouling. Here, we investigated the resistance against marine biofouling of a range of recently developed, biocide-free SLIPS commercial coatings. The fouling resistance performance was evaluated both in the lab and in the field by conducting multi-month immersion tests in high-fouling pressure environments. In the lab, we show that the coatings are able to largely deter settlement of marine mussels -one of the most invasive marine biofouling organisms-and to weaken their interfacial adhesion strength. The key design parameter of slippery coatings to minimize fouling is the thickness of the entrapped lubricant overlayer, which can be assessed through depth-sensing nanoindentation measurements. We find that the surface energy (i.e. hydrophobic vs. hydrophilic), on the other hand, does not significantly influence the antifouling performance of these coatings in lab-scale studies. After immersion in the field in stagnant waters, all coatings exhibited efficient foul-release capacity against macrofoulers, whereas under stronger hydrodynamic flow conditions, only weakly attached biofilms were detected with a bacterial community composition that is independent on the surface energy. These results suggest that these large-scale paintable coatings exhibit a strong marine biofouling resistance with low maintenance costs, which represents an important advantage from a commercial application perspective.
Marine structures often suffer from biofouling, which may lead to macrofouling by marine animals like marine worms and barnacles, weighing down the structures and increasing the drag. This paper analyses the effect of the newly fabricated biological anti-adhesion Titania-Polyurea spray
coating, which can effectively reduce biofouling from enriching on the surface. Through the surface characterization, bioassays and micro-channel drag-reduction test, the antibacterial effect caused by the nano-titanium dioxide is systematically studied. Compared to the different weight percentages
of nano-TiO2 in the coating system, the photocatalytic activity, riblet surface structure and hydrophobic wettability are supposed to be the key factors to reduce the flow resistance at a drag reduction rate of 3.0% and further enhance the anti-biofouling performance under dark
conditions.
Most of the industrial components are machined using the turning operation. In order to sustain in the global market, the industries strive to produce precision components. One such step towards attaining precision components is the introduction of inserts. Inserts are detachable components, brazed to the working tool. The most commonly used inserts are cemented carbide inserts. However, after a few machining operations, these inserts are subjected to wear. The life of the inserts is thus reduced by the wear. In order to reduce the wear and improve the life of a tool, the inserts are coated. Coated inserts are proven to improve the mechanical properties of machined workpieces. Nevertheless, the problem still persists while machining hard-to-machine materials. Therefore, there is a need for an alternate approach. In that case, nanomaterials can be applied to improve the properties and tool life. In nanomaterials, particles with a size of 10-9 m are used, exhibiting strong bonding along the boundaries. Due to this property, the material may resist the wear, improve the tool life and mechanical properties of machined materials. In the present work, cemented carbide inserts were coated with a nickel nanomaterial using the physical vapour deposition (PVD) technique, as nickel exhibits a high wear resistance and it is a hard material. The results showed that nickel-nanocoated inserts improve the tool life by reducing the wear of the inserts and the surface roughness of a machined workpiece as compared with uncoated inserts.
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