RU2525404C2 - Antiwear additive - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: present invention relates to an antiwear additive containing micelles based on iron oxide Fe₃O₄ grease molecules surrounded by oleic acid molecules, wherein the Fe₃O₄ micelle nucleus is doped with Co (II), with the following ratio of components, wt %: Co (II) - 6%, Fe₃O₄ - 94%.

EFFECT: improved tribotechnical and operational characteristics of the additive while minimising concentration of the additive in lubricant materials.

2 tbl, 1 dwg

Description

The invention relates to mechanical engineering, in particular to antiwear additives to lubricating oils to improve their tribological properties (plain bearings and piston pairs of compresses, pumps, internal combustion engines).

Magnetic fluids are known that change their properties depending on the magnetic field strength. They can also serve to reduce the coefficient of friction and the wear rate of rubbing nodes (see Berkovsky B.M., Medvedev V.F., Krakov M.S. Magnetic fluids. - M .: Chemistry, 1989. - p.159-166 ) Magnetic fluid differs from traditional lubricants in the presence of solid particles, therefore, they are mainly used in friction units of rolling and sliding bearings, in gearing of gears.

The closest, in fact, is an antiwear additive to diesel fuel (see RF patent No. 2276681, 2006). This additive contains molecules of solid plastic lubricant Fe ₃ O ₄ (iron oxide) having low shear resistance, which are surrounded by molecules of a surfactant - oleic acid C ₁₈ H ₃₄ O ₂ . The additive has the disadvantage that the magnetization of micelles decreases over time.

The technical task is to obtain antiwear micellar nanoparticles for use in tribological conjugations using lubricants with a more stable magnetization of additive particles in time.

The technical result is an increase in tribological and operational characteristics of the additive while minimizing the concentration of the additive in lubricants.

It is achieved by the fact that the Fe ₃ O ₄ micelle core is doped with Co (II) in the following ratio of components, wt.%: Co (II) - 6%, Fe ₃ O ₄ - 94%.

The proposed additive is a liquid from the main product with the introduction of phase-phase magnetite doped with cobalt.

Magnetite is a micelle core with low shear resistance, and of the surrounding surfactant molecules - oleic acid C ₁₈ H ₃₄ O ₂ . Oleic acid molecules are absorbed on the surface of magnetite particles as a result of the chemisorption process.

The core of nanoparticle particles, consisting of cobalt magnetite CoFe ₃ O ₄ , has a fairly high magnetic characteristics and chemical stability. Compared to the Fe ₃ O ₄ magnetite core, such a core has higher magnetic characteristics — the coercive force H _s , saturation magnetization σ _s and the squareness coefficient of the hysteresis loop λ _p . The properties of these ferromagnetic materials are shown in Table 1 (see Subbotin K.A., Mikhailenko A.I., Nedidova N.V. Influence of synthesis conditions on the magnetic properties of magnetite // Journal of Applied Chemistry. - 2000. - T. 73. - Issue 10. - S.1591-1595).

In order to confirm the improvement of the properties of the antiwear additive and to achieve the technical result, comparative tribological tests of the prototype additive and the proposed additive on a friction machine were carried out (see RF patent No. 115917, 2012). The tests were carried out according to the “shaft-bushing” scheme, using MS-20 base oil (GOST 21743-76) for 10 hours, the magnetic field strength was 20 kA / m, and the pressure in the friction zone was 1.5 MPa. The sliding speed was 0.1 s ⁻¹ , which corresponds to an unsteady (boundary) lubrication regime in a friction pair. The materials of the friction pair are B83 grade babbitt (sleeve) and steel 35 (shaft). The results of experimental studies showed the high efficiency of the proposed additives and confirmed its increased tribological and operational characteristics (table 2).

The additive was prepared as follows. The production scheme is shown in the drawing. The synthesis of cobalt magnetite was carried out by the method of single-stage co-precipitation of iron and cobalt with hydroxides with vigorous stirring. The obtained composition of cobalt magnetite CoFe ₃ O ₄ consisted of a base of Fe ₃ O ₄ (mass. 94%) and Co (mass. 6%). This substance was placed in a bath of a dispersant with oleic acid, where the dispersion process took place at a temperature of 28-30 ° C, at a frequency of 43 kHz for 20 hours. Then, a solution with cobalt-doped magnetite Fe ₃ O ₄ micelles was sent to a sedimentation chamber, where it precipitated for 8 hours.

The resulting solution was merged and sent for examination to determine the size of the obtained micelles. The optimal range of particle sizes of the additive is 10 ^-7 -10 ^-9 m. The sediment from the sedimentation chamber was sent for re-dispersion, the solution was also sent there after the process of measuring the particle size of the additive, if they were more than optimal.

The solution with micelles of the right size was sent to the drive. From the drive, the solution entered the mixing chamber, where at a temperature of 25-30 ° С and a speed of 300 rpm it was mixed with oil to obtain the final product — a lubricating composition with a CoFe ₃ O ₄ concentration of 0.01% by mass. This temperature and speed regime was selected with the aim of intensive mixing of the components of the lubricating composition while preventing the additive from evaporating during the mixing process.

The advantage of the proposed additive is its efficiency and effectiveness: reducing the concentration of the additive in lubricants does not impair its quality and performance. From table 2 it is seen that at the same concentration of additives (0.005-0.02 mass%), the proposed additive exhibits the best tribological properties: the friction coefficient decreases by 1.5-2 times, the wear rate decreases by 1.5-5 times. This proves the possibility and necessity of reducing the concentration of the proposed additives in lubricants by 25-40%.

The positive effect is that the proposed additive allows at a relatively low concentration to significantly reduce the coefficient of friction and the wear rate of friction pairs and, thus, increase the life of tribological conjugation of machines and mechanisms.

Table 1 Properties of ferromagnetic materials Structure N _c , E σ _s λ _p Fe ₃ O ₄ one hundred 60-78 0.31 CoFe ₃ O ₄ 560 60-78 0.38-0.44

table 2 Results of tribological tests of antiwear additives The composition of the additive Additive concentration in
base oil MS-20,% Coefficient of friction Wear rate Fe ₃ O ₄ + C ₁₈ H ₃₄ O ₂ 0.005 0.0042 3.2 * 10 ^-10 0.01 0.0035 2.7 * 10 ^-10 0.02 0.002 2.1 * 10 ^-10 CoFe ₃ O ₄ + C ₁₈ H ₃₄ O ₂ 0.005 0.0031 2.3 * 10 ^-10 0.01 0.002 1,2 * 10 ^-10 0.02 0,0009 0.35 * 10 ^-10

Information sources

1. Berkovsky B.M., Medvedev V.F., Krakow M.S. Magnetic fluids. - M .: Chemistry, 1989 .-- p.159-166.

2. RF patent No. 2276681, 2006

3. Subbotin K.A., Mikhailenko A.I., Nedidova N.V. The influence of synthesis conditions on the magnetic properties of magnetite // Journal of Applied Chemistry. - 2000. - T.73. - Issue 10. - S.1591-1595.

4. RF patent №115917, 2012

Claims (1)

Anti-wear additive with micelles in it based on molecules of solid plastic lubricant iron oxide Fe ₃ O ₄ with the surrounding molecules of oleic acid C ₁₈ H ₃₄ O ₂ , characterized in that the core of the Fe ₃ O ₄ micelle is doped with Co (II) in the following ratio components, wt.%:
Co (II) - 6%,
Fe ₃ O ₄ - 94%.

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