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The tribological behavior of traditional oil-in-water (O/W) lubricants (1.0 wt.%) and nano-TiO2 additive lubricants (1.0–9.0 wt.%) during micro rolling of titanium foils were analyzed. In this study, the surface morphologies of titanium foils under various lubrication conditions were assessed, and the corresponding lubrication mechanisms were revealed. The tribological behavior of nano-TiO2 additive lubricants during micro rolling of titanium foils was also explored through a series of characterization methods. The utilization of nano-TiO2 additive lubricants in micro rolling reduces the surface roughness of titanium foils. Moreover, it effectively inhibits the generation of indentations and cracks during rolling processes, enhancing the surface quality of rolled specimens. Additionally, owing to the synergism of rolling, tribo-film, mending and polishing effects of the nanoparticles, both the rolling force and surface roughness were minimized by using lubricants containing 3.0 wt.% TiO2 nanoparticles. Overall, an optimal concentration (3.0 wt.%) of TiO2 nanoparticles in water-based nanolubricants was obtained with enhanced tribological properties and lubrication performance during micro rolling of titanium foils. [ABSTRACT FROM AUTHOR]

In this work, an experimental investigation on the lubrication performance of water-based nanolubricant with TiO2 as nanoadditives was performed. The nanolubricants show excellent dispersibility and stability within 5 days after preparation. Additionally, the results show that the concentration of TiO2 nanoparticles significantly affects the lubrication performance of the prepared nanolubricant during microrolling. The excessive nanoparticles lead to agglomeration at the contact area, while the limited nanoparticles can hardly work during rolling processes. Instead, for a nanolubricant with 3.0 wt% of TiO2 nanoparticles, the nanolubricant is able to feed abundant nanoparticles continuously to the rubbing zone with little agglomeration, improving the surface quality of copper foils during microrolling. [ABSTRACT FROM AUTHOR]

In this paper, oil-in-water (O/W) based nanolubricants containing TiO 2 nanoparticles were developed to reduce the rolling force and improve the surface quality of rolled 304 stainless steel product. Practical hot rolling tests with and without application of lubricant were conducted to systematically investigate the effects of the developed O/W based nanolubricants on the rolling force, surface roughness, oxide scale thickness and tribological behaviour. The obtained results indicate that the nanoparticles can enter the deform zone with oil droplets to take a lubrication effect. The optimal lubrication effect can be achieved when the O/W (1% oil mass fraction) based nanolubricant with a TiO 2 mass fraction of 1.5% was applied. The microstructure of oxide scales formed on the hot rolled sample was not significantly affected by TiO 2 nanoparticles in the O/W based lubricant, but the oxide scale growth could be induced by TiO 2 nanoparticles. A discontinuous thin SiO 2 layer at the substrate-scale interface was observed. It can effectively reduce the formation of iron-rich oxides. The novel nanolubricant has a great potential to be applied in the hot steel rolling, to realise the cost-effective and environmental-friendly manufacturing process. [ABSTRACT FROM AUTHOR]

Electron backscatter diffraction (EBSD) of the microtexture in the tertiary oxide scale after hot rolling were investigated. The surface asperity flattening and grain refinement of Fe 3 O 4 were produced at a thickness reduction of 28% and a cooling rate of 28 °C/s. Microtexture development of Fe 3 O 4 manifests as a strong θ fibre parallel to oxide growth, including the {100}<001> and {001}<110> textured components, whereas the {0001}<10 1 ̅ 0> component dominates in α -Fe 2 O 3 as the favoured basal slip. The tribological effect of α -Fe 2 O 3 at the contact surface of steel and rolls was considered at low and high thickness reductions. The propagation of cracks along the Fe 3 O 4 grain boundaries could create a dish to collect nanoparticles during lubrication and thereby changed the wear rates. [ABSTRACT FROM AUTHOR]

Abstract SiC-graphene nanosheets (GNSs) core-shell nanoparticles were incorporated into alumina matrix composites. The composites showed refined grain sizes, increased toughness and hardness. Ball-on-disk wear tests were conducted and the results demonstrated that the coefficient of friction was reduced by 29.4%, and the wear rate was reduced by 90.1% for the composite containing 5 vol % SiC and 1 vol % GNSs at 90 N in comparison to monolithic alumina. These results are superior to Al 2 O 3 -graphene composites documented in the literature. The microstructure and topography of the wear scars were examined to understand the wear behaviour. GNSs-rich tribofilms were observed on the wear scar. The contributing mechanism of the self-lubricating and wear-resistance performance was explored. Highlights • The composites showed excellent wear-resistant and self-lubricating performance. • The reduction effect of the nanofiller on friction tends to be more significant under higher loads. • The enhancement is attributed to the improved microstructure, mechanical properties and GNSs-rich tribofilms. [ABSTRACT FROM AUTHOR]

A wet ball milling route was used to synthesise SiC-graphene core-shell nanoparticles in situ from graphite and SiC nanoparticles. Graphite flakes were gradually exfoliated into fresh graphene nanosheets (GNSs) without significant defects, which is attributed to mechanical shearing and moderate impaction forces between graphite flakes, milling balls and SiC nanoparticles during the wet milling. The non-destructive exfoliation is characterised by Raman, Fourier transform infrared and X-Ray photoelectron spectroscopies. The freshly produced GNSs are energetically unstable and thin enough to be flexible and this drives the in situ attaching and scrolling of GNSs on the SiC nanoparticles. The SiC nanoparticles and GNSs are well dispersed in the wet medium and the SiC nanoparticles are individually wrapped. It has been estimated that > 50% of the produced GNSs are wrapped around the SiC nanoparticles and these GNSs are generally ≤ 6 layers. [ABSTRACT FROM AUTHOR]

Abstract: DBSA-doped polyaniline powder (DBSA-PANI) was mixed with Fe nanoparticles to obtain the DBSA-PANI-Fe composite. Powder of the composite was compacted to the pellets to study the electrical property and magnetization characteristic by measuring the conductivity in 100–300K and the magnetization curve at room temperature. The conductivity of the composite pellet is linearly decreased from 0.25±0.02 to 0.07±0.01S/cm with increasing the Fe nanoparticle content from 0 to 70wt.%. For the pellets containing the Fe nanoparticles less than 70wt.%, the variation of conductivity with temperature reveals that the charge transport mechanism can be considered to be one-dimensional variable-range-hopping (1D-VRH). For the pellet with 70wt.%-Fe nanoparticles, however, the charge transport mechanism cannot be well understood in terms of the VRH model. All the DBSA-PANI-Fe composite pellets show a magnetic hysteresis loop and a hard magnetization characteristic. The saturation magnetization monotonously increases from 32 to 78emu/g with increasing the Fe nanoparticle content from 30 to 70wt.%. The saturation field and the coercivity are estimated to be about 5500 and 385Oe, respectively, independent of the Fe nanoparticle content. [Copyright &y& Elsevier]

To comprehend the role of water-based nanolubricant in micro flexible rolling, corresponding characterisation with respect to different concentrations of nanolubricants, surface roughness variation subjected to each micro flexible rolling phase and dispersion of nanoparticles (NPs) were studied systematically. The results reveal that increasing NPs get trapped into the surfaces from the thicker zone to the thinner zone. Downward transition zone with favourable deformation features leads to the smoother surface roughness. Nanolubricants can effectively decrease rolling traces due to the beneficial nanolubrication mechanisms. Notably, the maximum reduction for rolling force is around 18% for the case under 2.0 wt% nanolubricant rolling condition. The current study provides great potential insights in how nanolubrication takes effect in microforming areas. • Water-based nanolubricants distinctly reduce the rolling forces during micro flexible rolling. • Increasing NPs get trapped into the surfaces from the thicker zone to the thinner zone. • Downward transition zone with favourable deformation features leads to the smoother surface roughness. • More remained NPs are detected near the middle area along the transverse direction of the specimen. • Water-based nanolubricants can effectively decrease rolling traces due to the beneficial nanolubrication mechanisms. [ABSTRACT FROM AUTHOR]