Graphene reinforced waterborne polyurethane composite coatings were fabricated on steel surfaces. Superior anticorrosion properties were achieved by the addition of 0.4 wt% self-aligned graphene.
Purely semiconducting single-walled carbon nanotubes (s-SWNTs) with a narrow diameter distribution have been produced for HiPco SWNTs. A facile technique combining microwave irradiation with mixed-acid-assisted dispersion has proven efficient for enrichment of s-SWNTs. Using this process, both electronic type-dependent (metallic versus semiconducting) and diameter-dependent separation of SWNTs were simultaneously realized. By mildly controlling experimental conditions, metallic single-walled carbon nanotubes (m-SWNTs) and smaller s-SWNTs were preferentially removed, yielding purely diameter distribution-narrowed semiconducting nanotubes. Furthermore, the chemical structure of carbon nanotubes was restored after thermal annealing, as indicated by Raman and UV absorption investigations. The dual effects of semiconducting enrichment and diameter distribution narrowing, along with facile procedures, make this method promising for large-scale separation of SWNTs and therefore for industrial fabrication of nanotube-based electronics.
Natural serpentine powders are applicable as additives for various lubricating oils. However, no uniform theories explain their tribological performance, lubrication, and wear mechanism, especially their self-repairing mechanism. Herein, the influence of different nano serpentine powders (NSPs) contents in liquid paraffin on the friction and wear characteristics of steel balls and the self-repairing process of NSPs on the worn surface were studied. Results show that the optimal amount of NSPs was 0.5 wt %. Relative to those of the base oil, the friction coefficients and wear spot diameters were reduced by 22.8% and 34.2%, respectively. Moreover, the long-term tribological test shows that the wear scar diameter decreased slightly after 3 h, reaching the state of dynamic balance between wear and repair. The outstanding tribological performance should be attributed to the formed bilayer tribofilm, the first layer of which contains nanoparticles surrounded by lubricants and the second layer of which contains nanoparticles compacted onto the surface of the steel ball.
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