RU2484179C1 - Method of making antifriction composition - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: proposed method consists in placing antifriction composition between rubbing surfaces that modifies said surfaces and contains natural dispersed serpentine-bearing material mixed in hydrodynamic cavitation disperser with hydrocarbon binder. Note here that mineral-organic layer of organic derivatives of carbon, silicon, manganese and iron is formed on said surfaces. For this, serpentinite is used modified by natural high-molecular polysaccharide, preferably, chitosan, at particle size smaller than 1 mcm at the following ratio of components in wt %: serpentinite - 96.5-97.5, chitosan - 2.5-3.5.

EFFECT: higher efficiency, durability, longer life of antifriction coat.

4 cl, 4 tbl, 3 dwg

Description

The invention relates to lubricating compositions, in particular to compositions for processing friction pairs, and can be used in mechanical engineering for processing friction pairs, as well as in the operation of mechanisms and machines to extend the overhaul life or during repair and restoration work.

A known method of obtaining a composition for modifying metals and restoring metal surfaces, which is a mixture of serpentine, kaolinite, metasilicate as a catalyst and pyrolusite as a crystallizer, taken in the following ratio, wt.%: Sickle 40-70; kaolinite 10-40; pyrolusite 5-10; metasilicate 5-10. The dispersion of the mixture is 0.1-10.0 μm (see RU 2169208, IPC С23С 26/00, В23Р 6/00, 2001).

The disadvantage of this solution is the significant abrasiveness of the components of the material, the separation of which from serpentine is practically impossible or very laborious, which limits the use of this composition for metal modification and metal surface restoration to the cases of surface treatment with scoring, welding on viscous, refractory metals (within the tolerance) .

There is also known a method of forming an antifriction coating of contacting rubbing surfaces, which consists in placing an antifriction composition between them, which modifies the contacting rubbing surfaces, containing a natural dispersed serpentine-containing material mixed in a hydrodynamic cavitation dispersant with a hydrocarbon binder (see RU 2361015, IPC С23С 26/00, В23Р 6 / 00, 2008).

The disadvantage of this solution is the insufficiently high tribological characteristics of the antifriction composition, the need to use a sufficiently deficient component in the mixture — a pure serpentine-containing mineral (which is not common in all regions of the country). In addition, the inventors do not provide any data on the determination of the tribological properties of the composition according to the accepted methods, which does not allow to compare the characteristics of the known material with similar characteristics of other compositions of similar purpose.

The task of the invention is to increase the tribological characteristics of the antifriction composition.

The technical result manifested in solving the problem of the invention is expressed in a decrease in the frictional qualities of the mixture by increasing their relative mobility of the constituent parts of the solid particles of the composition. In addition, it is possible to use serpentinite - a rock (containing serpentine) - a less expensive and more common raw material. In addition, it is possible to use an inexpensive, commercially available polysaccharide to modify natural serpentinite. This creates the basis on which the cermet coating is formed. Due to this, the stability, strength and durability of the anti-friction coating are increased.

The solution to this problem is provided by the fact that the method of forming an antifriction coating of contacting friction surfaces, which consists in placing an antifriction composition between them, which modifies contact friction surfaces, containing a natural dispersed serpentine-containing material mixed in a hydrodynamic cavitation dispersant with a hydrocarbon binder, characterized in that during the formation of antifriction coatings of contacting rubbing surfaces on them form mi an organic-organic layer of organic derivatives of carbon, silicon, magnesium, iron and manganese, for which serpentinite, modified with a natural high-molecular polysaccharide, preferably chitosan, is used as a serpentine-containing material, with a particle size of solid particles less than 1 micron, with the following ratio of components in the mixture dispersed solid particles, wt.%:

serpentinite 96.5-97.5 chitosan 2.5-3.5

In addition, to modify serpentinite, a 1% solution of chitosan is prepared by dissolving it in 2% acetic acid, after which serpentinite with a particle size of 1-20 μm is introduced into a solution of chitosan at the rate of 100 g per 270-330 ml, after which this mixture is mixed for 3 hours, adding at the end a 5% ammonia solution until the suspension is neutralized, then the serpentinite is filtered off and dried to constant weight.

In addition, the antifriction composition is obtained in the form of a fine suspension, with a particle size of solid particles, preferably from 0.05 μm to less than 1 μm. In addition, preferably diesel fuel is used as a binder, while modified serpentinite is introduced into diesel fuel at the rate of 220-300 g of mixture per liter and subjected to hydrodynamic cavitation dispersion with a frequency of about 200 Hz, preferably at least 30 minutes.

A comparative analysis of the features of the claimed solution with the features of the prototype and analogues indicates the compliance of the claimed solution with the criterion of "novelty."

The features of the characterizing part of the claims provide the solution to the following functional tasks:

The sign "... in the process of forming the antifriction coating of the contacting rubbing surfaces, they form a mineral-organic layer of organic derivatives of carbon, silicon, iron, magnesium and manganese ..." provides the possibility of forming a high-strength layer of a protective film on the surface of the protected part, since this film is cermet, containing oxides of iron, silicon, magnesium and other elements.

The sign "... use serpentinite as a serpentine-containing material ..." makes it possible to use serpentinite - a rock (containing serpentine) - a less expensive and more common raw material.

A sign indicating that serpentinite is used "modified by natural high molecular weight polysaccharide" ensures the formation of additional slip planes in the interlayer space of serpentinite, which enhances its antifriction properties.

A sign indicating that chitosan is used as a natural high molecular weight polysaccharide makes it possible to use an inexpensive, commercially available substance for modifying natural serpentinite.

A sign indicating that the particle size of the solid in the suspension is less than 1 μm, minimizes the manifestations of the abrasiveness of the antifriction composition, which modifies the contacting friction surfaces.

A sign indicating that “for the modification of serpentinite, a 1% solution of chitosan is prepared by dissolving it in 2% acetic acid, after which serpentinite with a particle size of 1-20 μm is introduced into the chitosan solution at the rate of 100 g per 270-330 ml. then mix this mixture for 3 hours, adding at the end a 5% ammonia solution to neutralize the suspension, then the serpentinite is filtered off and dried to constant weight ”, provides a given degree of modification of serpentinite, which ensures an increase in its antifriction qualities due to framing in the interlayer space of serpentinite of additional slip planes.

Signs indicating that "the antifriction composition is obtained in the form of a fine suspension with a particle size of solid particles, preferably from 0.05 μm to less than 1 μm," ensure the efficiency of the composition and its hydrodynamic cavitation activation. Moreover, the specified range of dispersion of solid particles is determined empirically, and the lower limit of 0.05 microns is actually an indicator of the absence in the mixture of particles with a particle size of 1 or more microns. The main purpose of the range is the exclusion from the composition of the suspension of solid particles working as an abrasive that cause scratches (comparable in depth to the particle size), since according to our data, particle sizes from 1 μm and above are essentially solid materials that can destroy any metal coating and metal .

Signs indicating that “preferably diesel fuel is used as a binder” make it possible to use a common liquid hydrocarbon binder.

Signs indicating that “modified serpentinite is introduced into diesel fuel at the rate of 220-300 g of mixture per liter and subjected to hydrodynamic cavitation dispersion with a frequency of about 200 Hz, preferably at least 30 minutes,” determine the process parameters that provide an antifriction composition.

The claimed method is illustrated by drawings, where figure 1 schematically shows the structure of the modified serpentinite; figure 2-3 shows the data obtained using an atomic force microscope - shows the surface morphology of the sample (figure 2 - galvanic chromium; figure 3 - chromium hardened by serpentinite modified with chitosan).

To implement the inventive method using known equipment that provides the disintegration of the components of the composition and their subsequent hydrodynamic cavitation activation.

Serpentinite, chitosan and diesel fuel are used as composition ingredients.

Serpentinite is a rock containing serpentine that has the following elemental composition:

SiO ₂ MgO Fe ₂ O ₃ Cao MnO H ₂ O 37.6 28.5 17.5 2.6 2.3 11.2

Its gross formula is: 4.5MgO · 0.7Fe ₂ O ₃ · 0.3 CaO · 0.2MnO · 4SiO ₂ · 4H ₂ O. The size of the grinding of serpentinite (before it is processed in the dispersant) is up to 1-10 microns.

Chitosan has the following characteristics:

Molecular η 1% solution, Power Content% mass, D mmg / s deacetylation H ₂ O FROM N <200000 88.0 84.0 8.8 41.8 7.5

Uses ordinary diesel fuel.

Serpentinite, prepared for modification, is ground to a particle size of 2-10 microns (at the same time, a 1% solution of chitosan is prepared by modifying serpentinite by dissolving it in 2% acetic acid). The ground serpentinite is then introduced into the chitosan solution at the rate of 100 g of serpentinite per 270-330 ml of chitosan solution. Next, the mixture is placed in a container equipped with a mechanical stirrer with a drive (not shown in the drawings), and the mixture is stirred for 3 hours. At the end of the mixing process, add 5% ammonia solution until the mixture reaches pH 8. Next, the serpentinite is filtered off in a known manner and dried to constant weight. The structure of the modified serpentinite (see Fig. 1) differs from the initial one, since the polysaccharide is introduced into the interlayer space of the silicate, changing it.

X-ray phase analysis was performed on an Advance-D8 diffractometer (Bruker). The data of x-ray phase analysis (XRD) confirm the assumption of a modification of the interlayer space. The absence of reflection at d = 14Å, which is present in the initial one, indicates the filling of the interlayer space in serpentinite. It is known (see Wheatley T. Determination of molecular structure. Because of World: Moscow. 1970. 293 s) that the intensity of Bragg reflection corresponds to the density of filling the layer with atoms. The intensity of the XRD of modified serpentinite decreases sharply due to the amorphous polysaccharide. Moreover, there is an unchanged number of reflections due to atomic planes directly in the silicate layer, and their intensity is close to the intensity in the initial serpentinite.

To prepare the composition, a mixture of dispersed solid particles is prepared, including modified serpentine in the stated proportions (serpentinite (96.5-97.5, wt.%), Modifying polysaccharide (2.5-3.5 wt.%), Preferably chitosan, with initial particle size up to 2-10 microns.

Further, this mixture of dispersed solid particles is introduced into diesel fuel at the rate of 220-300 g of the mixture per liter of diesel fuel and processed in a hydrodynamic cavitation dispersant with a frequency of about 200 Hz, preferably at least 30 minutes, providing a final particle size of the solid particles in suspension, preferably in the range from 0 , 05 μm to 1 μm.

For comparative tribotechnical tests, the samples were made of CVG steel in the form of rollers with a diameter of 45 mm, a width of 10 mm, some of the samples were coated with a 12-15 μm thick chrome coating. Before testing, the samples were polished with diamond paste to Ra = 0.063 μm.

The surface modification of a rotating sample was carried out by rubbing at a load of 300 N for 5 min. The thickness of the modified layer reaches 2-3 microns.

Tests on a universal machine model UMTVK were carried out according to the "roller - roller" scheme in the conditions of boundary friction at a constant sliding speed of 0.628 m / s. A roller made of HVG steel with a hardness of 60-61 HRC was used as a stationary sample. Lubrication of a friction pair was carried out by the drop method (40-50 drops per minute). For lubrication, diesel fuel of the L-0.5 brand was used in accordance with GOST 305-82. As an artificial pollutant, quartz dust with a particle size of 1-5 microns was used. The concentration of pollutant in the fuel was - 1%. The test time for each friction pair was 4 hours. The load varied from 100 to 500 N.

Table 1 Comparative tribological test results Friction pair Load, N Test time, h t _max , ° C k _tr Average wear rate, g / h coverings HVG Hvg chrome one hundred 0.5 49 0.171 0.0018 0.0068 200 0.5 64 0.142 0.0012 0.0050 300 1,0 78 0.148 0.0012 0.0015 500 2.0 110 0.174 0,0008 0.0014 CVH - serpentinite hardened chromium one hundred 0.5 42 0.113 0 0,0004 200 0.5 52 0.128 0,0006 0.0010 300 1,0 64 0.128 0.0013 0.0025 500 2.0 8 0.128 0.0013 0.0011 CVH - chrome hardened by serpentinite modified with chitosan one hundred 0.5 40 0.113 0 0,0003 200 0.5 51 0.123 0,0003 0,0008 300 1,0 62 0.122 0,0005 0.0019 500 2.0 95 0.122 0,0005 0.0010

An analysis of the test results showed that the composition - chromium hardened by serpentinite modified with chitosan over the entire load range has lower values of the coefficient of friction and wear. The amount of wear of the coating is reduced by more than 2 times. In this case, the wear rate of the mating part also decreases.

To determine the tribotechnical characteristics under conditions of hard loading of the studied materials, additional tests were carried out (Tables 2 and 3) for 1 h at a load of 500 N. The running-in time at a load of 300 N was 5 minutes. As an optimization parameter were taken: the wear resistance of the coating and the associated parts, the coefficient of friction after running in.

table 2 The results of comparative tribological tests with hard loading of the interface Coating composition The amount of wear of the coating, mg The amount of wear of steel CVG, mg The total value of the wear of tribological conjugation, mg Friction coefficient after running in Chromium 1.8 7.2 9.0 0.209 Serpentinite hardened chrome 1,0 1.9 2.9 0,120 Chromium-hardened serpentinite modified with natural polysaccharide 0.5 1.8 2,3 0,120

Table 3 Changes in the friction coefficients during tribotechnical testing under hard loading of the interface Coating composition Test time, min 5 10 fifteen twenty thirty 40 fifty 60 Chromium 0.266 0.274 0.237 0.217 0.220 0.220 0.217 0.212 Serpentinite hardened chrome 0.166 0.151 0.163 0.137 0.149 0.124 0.127 0,120 Chromium-hardened serpentinite modified with natural polysaccharide 0.166 0.137 0.143 0.143 0.137 0.118 0,120 0,120

Based on the tribotechnical tests, it was found that the use of chitosan-modified serpentinite for friction under high loads reduces the coating wear by 2 times (Table 2), the values of the friction coefficient during the tests have a smaller scatter of values and values.

When using the claimed composition, several effects are manifested that provide an increase in the antifriction properties of the composition:

- reducing the sliding load relative to each other silicate layers of modified serpentinite;

- the formation of an antifriction layer due to the incorporation of silicon, magnesium and manganese ions into the crystal lattice of the test material, and a base is created on which a ceramic-metal coating is formed. The proof of this is the study of the obtained coating using x-ray electron spectroscopy and atomic force microscopy (AFM). The surface morphology of the sample was studied using an NTMDT Solver P46 atomic force microscope.

The X-ray photoelectron spectrum was obtained on an ultrahigh vacuum photoelectronic spectrometer (Omicron, Germany) with a hemispherical electrostatic analyzer (radius of curvature 125 mm). The source is an X-ray gun with a magnesium anode (MgK line _α 1253.6 eV).

Before the study using AFM and XPS, the surface of the sample was cleaned of the organic film by argon etching three times directly in the chamber of a photoelectron spectrometer at a vacuum of 10 ^-7 torr and a voltage of 1000 volts at a point.

The resulting composition of the cermet film at a depth of 100 nm is expressed in atomic percent:

- for serpentinite C = 47.60, O = 22.93, Cr = 18.35, Na = 2.31, Si = 3.47, Mn = 1.95, Fe = 1.85, Al = 1.54,

for chitosan modified serpentinite, C = 58.20, Cr = 10.85.0 = 21.83, Si = 3.72, Na = 1.78, Al = 1.37, Fe = 1.15, Mn = 1.10.

The high content of carbon, silicon, manganese and aluminum indicates the formation of an antifriction cermet coating, which is clearly visible on a surface image modified with a composition of serpentinite and chitosan made using AFM (Fig. 3).

The optimal topography, providing a good oil-retaining surface, has a chromium surface after hardening with serpentinite modified with a polysaccharide (figure 3). Microroughness profiles obtained perpendicular to the direction of hardening after hardening with an organomineral composition based on serpentinite are close to an almost flat line (Table 4). Periodic microroughnesses, located on the surface in the direction of hardening and not having sharp protrusions, provide a surface with good lubricity-holding ability under friction at boundary lubrication, and high wear resistance. Due to the minimum specific pressure on the mating surfaces and the availability of lubricant, the wear of the surface mated to the composite coating is reduced, as well as the friction coefficient and temperature in tribocontact.

Table 4 Roughness parameters of samples from plunger couples restored by applying various wear-resistant coatings The material of the surface layer of the plunger Roughness parameters Arithmetic mean deviation of the profile R _a , microns The height of the profile irregularities at ten points R _z , microns The average step of the roughness profile S _m , microns The angle of inclination of bumps, degrees Chromium

$$\frac{\text{0}\text{, 079-0}\text{091}}{\text{0}\text{, 085}}$$

$$\frac{\text{0}\text{, 331-0}\text{420}}{\text{0}\text{, 375}}$$

$$\frac{\text{0}}{\text{0}}$$

$$\frac{\text{3}\text{, 6-14}\text{,one}}{\text{6}\text{,9}}$$

Serpentinite hardened chrome $$\frac{\text{0}\text{, 038-0}\text{, 068}}{\text{0}\text{053}}$$

$$\frac{\text{0}\text{, 159-0}\text{, 279}}{\text{0}\text{, 219}}$$

$$\frac{\text{0}\text{, 003-0}\text{, 903}}{\text{0}\text{, 453}}$$

$$\frac{\text{one}\text{, 7}-\text{17}\text{,9}}{\text{6}\text{,8}}$$

Chitosan modified serpentinite hardened chromium $$\frac{\text{0}\text{, 031-0}\text{057}}{\text{0}\text{, 044}}$$

$$\frac{\text{0}\text{, 148-0}\text{, 238}}{\text{0}\text{, 194}}$$

$$\frac{\text{0}\text{, 894-1}\text{, 390}}{\text{one}\text{, 140}}$$

$$\frac{\text{0}\text{4-8}\text{, 3}}{\text{2}\text{, 2}}$$

Note. The numerator shows the interval of parameter values (the smaller value being determined perpendicular to the direction of processing, and the larger value is determined in the direction of processing), and the denominator is the average value.

Claims (4)

1. A method of forming an antifriction coating of contacting rubbing surfaces, which consists in placing an antifriction composition between them that modifies the contacting rubbing surfaces, containing a natural dispersed serpentine-containing material mixed in a hydrodynamic cavitation dispersant with a hydrocarbon binder, characterized in that during the formation of the antifriction coating of the contacting rubbing surfaces , they form a mineral-organic layer of organic carbon, silicon, manganese and iron alone, for which, serpentine-containing material modified with a natural high-molecular polysaccharide, preferably chitosan, is used when the particle size of the solid is less than 1 μm, with the following ratio of components in the mixture of dispersed solid particles, wt.% :
serpentinite 96.5-97.5 chitosan 2.5-3.5 2. The method according to claim 1, characterized in that for the modification of serpentinite, a 1% solution of chitosan is prepared by dissolving it in 2% acetic acid, after which serpentinite with a particle size of 1-20 μm is introduced into the chitosan solution at the rate of 100 g per 270-330 ml, after which this mixture is stirred for 3 hours, at the end adding 5% ammonia solution to neutralize the suspension, then the serpentinite is filtered off and dried to constant weight. 3. The method according to claim 1, characterized in that the antifriction composition is obtained in the form of a fine suspension with a particle size of solid particles, preferably from 0.05 μm to less than 1 μm. 4. The method according to claim 1, characterized in that preferably diesel fuel is used as a binder, while the mixture of modified serpentinite is introduced into diesel fuel at the rate of 220-300 g of mixture per liter, and subjected to hydrodynamic cavitation dispersion with a frequency of about 200 Hz preferably not less than 30 minutes

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