Study on the Ferrofluid Lubrication with an External Magnetic Field

Abstract

Ferrofluids (FFs) are stable colloidal systems consisting of single-domain magnetic particles with a diameter of approximately 10 nm coated with surfactants and dispersed in a carrier liquid. By applying an external magnetic field, these fluids can be confined, positioned, shaped and, controlled at desired places. The load capacity of a lubricant film of FF can also be increased with an appropriate magnetic field. In this paper, Fe 3 O 4 -based FFs with different saturation magnetizations (M s ) were prepared by the co-precipitation technique. The tribological experiments of FFs under different magnets distributions were conducted on a ring-on-cylinder tribometer. The results show that the magnetic field intensity distributions on the rubbing surface have a significant influence on the tribological properties of FFs. The experimental results also indicate that FFs have a good friction-reduction performance in the presence of an external magnetic field compared with the carrier liquid and that its lifetime of friction can be greatly improved.

On the global well-posedness of a class of 2D solutions for the Rosensweig system of ferrofluids

“…The versatility of such material and its peculiar property of being controlled via a magnetic field made it suitable to be later used in a whole variety of applications: ferrofluids are for instance used in loudspeakers in order to cool the coil and damp the cone [25], as seals in magnetic hard-drives [29], in order to reduce friction [19] or enhance heat transfer [20], [34]. We refer the interested reader to [39], the introduction of [27] and references therein for a survey of potential applications of ferrofluids.…”

Ferrofluids lubrication: a status report

“…Figure shows the optical microscope images of worn scar lubricated with carrier liquid and FFs. After that, the tribological properties of FFs under different magnet distributions were examined experimentally . The four samples covered with FFs are shown in Figure .…”

“…Cylinders covered with ferrofluids: (a) five magnets ( φ 5.0 mm × 4.0 mm), (b) eight magnets ( φ 4.0 mm × 4.0 mm), (c) 14 magnets ( φ 3.0 mm × 4.0 mm) and (d) 32 magnets ( φ 2.0 mm × 4.0 mm) …”

“…After that, the tribological properties of FFs under different magnet distributions were examined experimentally. 89 The four samples covered with FFs are shown in Figure 14. Columniform NdFeB magnets with different sizes (magnetic property: 35MGOe) were used, while the area ratio of the permanent magnets on each cylinder surface, as well as the total volume in each cylinder, was the same.…”

“…Optical microscope images of worn scar lubricated with carrier liquid and ferrofluids: (a) before test, (b) lubricated with carrier liquid and (c) lubricated with ferrofluids. Cylinders covered with ferrofluids: (a) five magnets (φ5.0 mm × 4.0 mm), (b) eight magnets (φ4.0 mm × 4.0 mm), (c) 14 magnets (φ3.0 mm × 4.0 mm) and (d) 32 magnets (φ2.0 mm × 4.0 mm) 89.…”