Water-based lubricants with different fractions of TiO2 nanoparticles ranging from 1.0 to 9.0 wt% were utilized to study the lubrication mechanisms during micro rolling tests and the tribological behaviour of nanolubricants during the micro rolling of copper foils. The results indicate that the application of TiO2 nanolubricants remarkably improves the surface quality of rolled copper foils during rolling processes. For lubricants with inadequate TiO2 nanoparticles, it is found that few TiO2 nanoparticles enter the contact regions between the rolls and foils, causing insufficient lubrication during rolling processes. Instead, for lubricants with excessive TiO2 nanoparticles, obvious agglomeration occurs at the contact regions and promotes the generation of voids on the surface of the rolled foils, thereby deteriorating the surface quality of the rolled copper foils. In addition, it is found that the surface quality of rolled foils is improved by utilizing a large reduction ratio. Overall, the fraction of 3.0 wt% TiO2 nanolubricants is optimal to improve the lubrication conditions at the contact regions, thereby improving the surface quality of the rolled copper foils.
In the present work, a comparison between traditional oil‐in‐water (O/W) based lubricant and nano‐TiO2 additive water‐based lubricants was made to explore the lubrication effects during rolling of ferritic stainless steel (FSS) strips. The results show that marked reduction in rolling force and improvement in the surface quality can be achieved by utilisation of water‐based nanolubricant, which can be attributed to the synergism of rolling effect, mending effect, polishing effect and protection film. An optimal concentration of 3.0 wt% TiO2 nanoparticles is found to exhibit excellent lubrication effects with sufficient nanoparticles at real contact regions without aggregation, leading to 10% reduction in the surface roughness during rolling of FSS strips.
TiSiCN composite coatings with different C contents were prepared on Cr buffer layer by plasma‐enhanced magnetron sputtering. The structure, composition, surface, and cross‐sectional morphology of the coatings were characterized by X‐ray photoelectron spectroscopy, X‐ray diffraction, Raman spectroscopy, scanning electron microscope, and atomic force microscope. The hardness, elastic modulus, and tribological performance of the coatings were evaluated by nanoindentation and reciprocating friction tests. The results showed that the TiSiCN composite coatings are amorphous structure composed of TiCN compound and microcrystalline graphite, and amorphous phases. The increase of C content changed the content and distribution of TiCN ceramics nanocrystal, amorphous Si3N4 and amorphous carbon (sp3‐ and sp2‐hybridized C), thus affecting the hardness and friction behavior of the coatings. The hardness of the composite coatings was related to the content of TiCN phase and sp3‐C in the coatings. The TiSiCN composite coating with C content of 68.2% had lower coefficient of friction and the lowest wear rate.
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