RU2401287C2 - Method of preparing polymer antifriction coating - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: polymer antifriction coatings are deposited on solid surfaces made from metal, ceramics and polymer materials in order to reduce coefficient of friction and wearing of contact surfaces in mechanical engineering, aircraft construction, shipbuilding and in petrochemical and gas industry. Preparation of the coating involves treatment of the surface of an article with a cleaning agent, drying, heating the surface to temperature higher that boiling point of epilam, application of a solution of an organofluorine surfactant (fluoro surfactant), perfluropolyoxyalkylene or perfluorinated polyalkylene oxide compound onto the surface of epilam. The fluoro surfactant solution is applied using a gas stream which is directed and curled around a longitudinal axis, where the said gas stream is fed at 30-300 g/s while epilam flows at 5-15 g/s. The gas is selected from a group which includes air, nitrogen and inert gas. The coating then undergoes thermofixation. Epilam is fed into the gas stream using an ejector. The gas stream curled around the longitudinal axis is created using a screw and the directed gas stream is obtained using a supersonic nozzle.

EFFECT: antifriction polymer coatings with good tribotechnical properties on the surface of large articles.

4 cl, 4 tbl, 3 dwg, 6 ex

Description

The invention relates to methods for producing polymer antifriction coatings that are applied to solid surfaces from metals, ceramics and polymeric materials, and can be used in mechanical engineering, aircraft manufacturing, shipbuilding, as well as in the petrochemical and gas industries.

In mechanical engineering, a cardinal solution is required to the problem of reducing wear in friction units in order to increase product life. Very relevant is the task of reducing traffic resistance in shipbuilding and aircraft manufacturing. During operation of pipelines for transporting gases or liquid products, friction losses occur on the pipe walls, as a result of which considerable energy is required for pumping these products. A far from complete list of these problems can be solved by creating a polymer antifriction coating on the surface of ship hulls, aircraft fuselages, or internal surfaces of pipelines. However, existing technologies for producing anti-friction coatings have a number of disadvantages that do not allow obtaining high-quality coatings while minimizing the cost of work.

A known method of producing a polymer antifriction coating, including cleaning the surface of the product using ultrasound, drying under the influence of infrared rays, applying the antifriction composition of epilam — a solution of an organofluorine surfactant (Fluorosurfactant) —perfluoropolyoxyalkylene or perfluorinated polyalkylene oxide compound by immersing the product in this solution at a temperature of 50-60 ° C with simultaneous exposure to ultrasound, heat treatment of the coating using an infrared emitter. While cleaning and drying the surface of the product is carried out in the first container, and the application of antifriction composition and heat treatment of the coating in the second container (Patent RU 2280051 C1, C09D 127/12, 07.20.2006).

The disadvantage of this method is that its use requires the use of special containers, ultrasonic and infrared emitters, and for products with large dimensions, the implementation of this method is almost impossible.

The closest analogue of the proposed technical solution is a method for producing a polymer antifriction coating, including cleaning the surface with a cleaning agent, drying the cleaned surface at 20-200 ° C, applying the antifriction composition of epilam - 0.1-10.0% solution of organofluorine surfactant (Fluorine-surfactant) - perfluoropolyoxyalkylene or perfluorinated polyalkylene oxide compounds by immersion of the product in this solution or by aerosol spraying, heat treatment of the coating (Patent RU 2139902 C1, . C09D 127/12, 20.10.99).

The disadvantage of this method is that when applying the composition by aerosol spraying, it is impossible to obtain a coating that is uniform in thickness and uniform in operational properties. In addition, with aerosol spraying, freon, which is prohibited for use in an open atmosphere, is used as an epilam carrier. The method is also not applicable to create anti-friction coatings on products with large dimensions.

The technical result of the invention is to increase environmental safety and expand the technological capabilities of the method, as well as improving the tribological properties of the polymer antifriction coating.

This result is achieved by the fact that in the method of producing a polymer antifriction coating on the surface of the product, including surface treatment with a cleaning agent, drying, applying to the surface of the epilam — a solution of an organofluorine surfactant (Fluorosurfactant) —perfluoropolyoxyalkylene or perfluorinated polyalkylene oxide compound with a directed gas flow and thermofixation of the coating; after drying, the surface is additionally heated to a temperature exceeding the boiling point of epilam, nan fluorine-surfactant solution is carried out by directing and swirling around its longitudinal axis a gas stream supplied with a flow rate of 30-300 g / s at an epilame flow rate of 5-15 g / s, and gas selected from the group consisting of air and nitrogen is used as gas and inert gas. In this case, the epilame is introduced into the gas stream by an ejector device, a gas stream swirling around its longitudinal axis is created by means of a screw, and a directed gas stream is obtained using a supersonic nozzle.

Epilams are compositions containing organofluorine surfactants (Fluorosurfactants) - perfluoropolyoxyalkylene or perfluorinated polyalkylene oxide compounds and an organic solvent.

The solvent used is perfluoromethylcyclohexane (PFMCG), alcohols, trichlorethylene, tetrachlorethylene, freons, freons, etc.

As epilam can be used: Autocon - 0.5, Autocon - 20, which are solutions of perfluoric acid grade 6 MFK-180 in perfluoromethylcyclohexane (PFMCG) or chladone 350; Amidofen (see Industrial organofluorine products: Ref. Ed. / B.N. Maksimov, V.G. Barabanov, I.L. Serushkin and others - 2nd edition, trans. And additional - St. Petersburg: Chemistry, 1996 .-- S.456-458); 6SFK-180-05, 6SFK-180-20, 6SFK-180-50 (see Patent RU 2278875 06/27/2006); Polizam 05, Polizam 20, Efren-1, Efren-2 (see Patent RU 2280051 07/20/2006.), Etc.

A distinctive feature of the proposed method is that the anti-friction composition is applied to the treated surface using a supersonic two-phase flow of gas and epilame, swirling around its longitudinal axis and creating kinetic energy proportional to the square of the flow velocity. The introduction of epilam into the gas stream using an ejector and the subsequent swirling of the stream by means of a screw makes it possible to achieve uniform distribution of the drops of epilam in the gas stream. The presence of the rotational component of the flow rate allows the processing of hard-to-reach closed product cavities due to centrifugal forces moving epilame droplets to the periphery of the flow. The axial component of the flow moves epilame droplets along the surface to be treated. Thus, a two-phase flow having a complex translational-rotational motion allows the surface to be uniformly treated and, at the same time, to improve the quality of processing due to the presence of high speed epilame droplets, which allows fluorine-surfactant to be introduced into the pores and microcracks of the material when it hits a heated surface.

At the moment of dropping of epilam drops on a surface heated above its boiling point, there is a local increase in pressure and concentration of Fluorine-surfactant in the contact zone, due to evaporation of the solvent, which also contributes to the penetration of Fluorine-surfactant into the deep layers of the product material. In turn, the use of air, nitrogen or an inert gas as a carrier epilame significantly increases the environmental safety of the method.

Fluorine-surfactant is adsorbed by the surface and forms a thin (about 30-50 Å) film on it through chemisorption and chemical bonds. In addition, as a result of epilation, the electric potential of the surface of the material decreases. As a result of this phenomenon, when a gas or liquid flows around the epilated surface, a boundary layer does not form in accordance with the known physical model due to the absence of electromagnetic bonds between the molecules of the solid surface and the molecules of gas or liquid. The practical result of this phenomenon is realized in reducing friction losses during flow around solid surfaces and, accordingly, in increasing the channel cross sections by the thickness of the displacement boundary layer.

The proposed method allows to obtain an anti-friction coating on the open and closed surfaces of products having large dimensions.

According to the results of the experiments, the optimal ratio of the mass flow rate of epilam to gas flow rate is in the range of 0.05-0.2. When the ratio of costs less than 0.05, the process of epilating requires an increase in technological time to obtain an antifriction coating with high tribological properties. If the expense ratio is exceeded by 0.2, there is an increase in epilam consumption without further improving the quality of the coating.

Surface preparation for applying the antifriction composition of epilam is carried out according to known technology.

The following can be used as cleaning agents during surface preparation: acetone, white spirit, gasoline, nefras, alcohols, PMFCH, freons, etc. Drying of the cleaned surface is carried out at a temperature of 20-120 ° C.

Helium, neon, argon, krypton, xenon or radon can be used as an inert gas.

Figure 1 schematically shows the installation for implementing the proposed method when applying an antifriction composition to the channels of the turbine blades and the inner surfaces of the pipes.

The installation consists of a receiver 1 with a capacity of 100 liters, connected by an inlet pipe to a compressor 2. An electromagnetic valve 3 is installed on the outlet pipe, an ejector device 4 for injecting and spraying epilame from a supply tank 5, a device 6 for twisting a two-phase gas and epilame stream, including a screw enclosed in a housing. A supersonic Laval nozzle 7 is designed to form a directed two-phase flow. A test item 9 is mounted on the platform 8. The unit includes a heating device consisting of an industrial hairdryer 10 and compressor 11. Switching the unit's operation modes (heating the product or applying an antifriction coating) is carried out by electromagnetic valves 12 and 13.

A computer is used to control the operation of the installation and the processing of the received data.

The proposed method is implemented as follows.

The receiver 1 is filled with gas (nitrogen, inert gas, or air) to a pressure of 8 atmospheres. The installation is in the "heating" state, for which the valve 12 closes, and the valve 13 opens.

Treated with a cleaning agent and dried product 9, it is fixed on the platform 8 and blown with heated air supplied through an industrial dryer 10 from the compressor 11. The heating time is set experimentally and is 100 seconds for this installation. The product is heated to a temperature above the boiling point of epilam, on average, to 60-90 ° C. Temperature control is carried out by a thermal imager.

After heating, the purge is turned off and held for 60-100 seconds in order to equalize the temperature field of the product.

Upon reaching the average surface temperature of the product within 50-60 ° C, the valve 13 closes and the valves 3 and 12 open, and gas is released from the receiver at a speed of 30-300 g / s, depending on the product being processed.

During the outflow of gas from the receiver, epilam is injected into the gas stream by an ejector 4 from the supply tank 5 at a speed of 5-15 g / s.

The two-phase gas and epilame stream created in the ejector passes through the device for twisting the stream 6, consisting of a screw installed in the housing and connecting fittings, and then enters the Laval supersonic nozzle 7, directing the swirling flow into the product’s internal channel. Processing time is 10-20 s.

Under the influence of centrifugal forces, epilame droplets fall on the wall, and a gas stream moves unevaporated epilame droplets to the outlet section of the article.

When drops of epilam get on a heated wall, the solvent partially passes into a gaseous state. In this case, the penetration of Fluorine-surfactant into the layers of the material of the product is intensified due to the presence of local hydroblows that occur when the epilame drops touch the heated wall. The magnitude of hydroshocks is due to the high kinetic energy of the droplets, proportional to the droplet mass and their squared velocity, exceeding the speed of sound in the presence of a supercritical pressure drop between the gas pressure at the inlet of the Laval nozzle and the ambient pressure.

After coating and its heat setting at a temperature of 40-70 ° C for 30-90 minutes, the product is purged with air in order to calculate the parameter that determines the hydraulic loss in the internal channels of the product. As the specified parameter, the equivalent area of internal holes (channels) is selected and calculated, which is an estimate of their throughput.

The methodology for assessing the throughput capacity of through passage channels of products when they are purged with gas is one of the difficult problems in gas dynamics. One solution to this problem is to purge the product with gas from the receiver and calculate its flow rate at a supercritical differential between the pressure in the receiver and in the environment. For the proposed method, as an estimate of the throughput of the passage channels (in the general case of channels of complex shape) is the "equivalent area", conditionally corresponding to the passage area of the throttle washer having a hydraulic resistance equal to the hydraulic resistance of the tested product. The specified technique is patented (patent RU 2303778 07/27/2007) by one of the co-authors of the invention.

Equivalent area F is calculated by the formula:

- является постоянной величиной для конкретной испытательной системы,Where

- is a constant for a particular test system,

P ₁ - pressure in the receiver at the initial time t ₁ purge,

P ₂ - pressure in the receiver at the final moment t ₂ purge,

t ₁ is the initial moment of purge time,

t ₂ is the final moment of the purge time,

V is the volume of the receiver,

T is the current gas temperature in the receiver,

R is the gas constant

m is the constant for the gas used in the experiment, which is a function of the adiabatic exponent for a given gas.

Example 1

As a test object, 5 cooled turbine blades were used.

Each of the 5 blades, treated with various cleaning agents and dried at temperatures in the range of 20-120 ° C, was fixed on the platform 8 (Fig. 1), heated to a temperature of 60 ° C and processed according to the above procedure. The Avtokon-20 epilame was injected at a flow rate of 5 g / s with an ejector device 4 into a helium stream supplied with a flow rate of 30 g / s from receiver 1. The obtained two-phase flow, consisting of helium and epilame, was twisted around the longitudinal axis by screw 6 and sent by supersonic nozzle 7 into the inner channels of the scapula. After applying epilamum for 10 s, the resulting coating was subjected to heat setting for 30-90 min. After blowing the blades with air, the equivalent channel area of each blade was calculated by the formula (1).

In order to carry out mathematical processing of the experimental results, the purge was carried out 30 times before applying the epilam and 30 times after epilating.

The calculation results are presented in table 1.

Example 2

Steel pipes with a diameter of 20 mm and a length of 200 mm were used as the test object. Preliminarily, the pipes were spilled with water on a hydrostand and purged with air in order to evaluate hydraulic losses during the flow of liquid and gas.

Each of the 5 steel pipes was treated as in example 1, but the Avtokon-0.5 epilame was injected at a flow rate of 10 g / s into a nitrogen stream supplied with a flow rate of 165 g / s from receiver 1. After blowing the pipes with air, the equivalent the area of the internal holes of the pipes according to the formula (1).

In order to carry out mathematical processing of the experimental results, the purge was carried out 30 times before applying the epilam and 30 times after epilating.

The calculation results are presented in table 2.

In order to assess the hydraulic losses in the pipes at the outflow of liquid (water) before and after epilation, the pipes were poured with water on a hydro stand, according to the obtained data, the water flow rate was calculated at a fixed pressure drop. The test results are shown in table 3.

Example 3

5 steel pipes with a diameter of 20 mm and a length of 200 mm, previously spilled with water and blown with air, were treated as in example 2, but the Polizam-20 epilam was injected at a flow rate of 15 g / s into a stream of air supplied at a speed of 300 g / s from the receiver 1. After blowing the pipes with air, the equivalent area of the through holes was calculated.

The calculation results are presented in table 2. The results of water consumption before applying the antifriction coating and after are presented in table 3.

Example 4

5 cooled turbine blades were processed as in example 1, but the Avtokon-0.5 epilame was injected at a flow rate of 4 g / s into an argon stream supplied with a flow rate of 28 g / s from receiver 1. After blowing the blades with air, an equivalent area was calculated channels according to the formula (1).

The calculation results are presented in table 1.

Example 5

5 steel pipes with a diameter of 20 mm and a length of 200 mm were processed as in Example 2, but the Efren-1 epilam was injected at a flow rate of 16 g / s into the air stream supplied with a flow rate of 305 g / s from receiver 1. After blowing the pipes air calculated the equivalent area of the through holes according to the formula (1).

The calculation results are presented in table 2.

According to the results of mathematical processing, the difference in the data obtained before and after applying the epilame is significant (exceeds the measurement and calculation error), which can be explained by a decrease in friction losses. A relatively small increase in the throughput capacity of the internal channels of the blades and pipes as a result of surface epilation is due to the fact that in the total amount of hydraulic losses during gas flow in the internal channels of the blade and pipelines, the friction losses are also relatively small compared to other losses.

According to the results of mathematical processing of the data obtained before applying the antifriction composition to the inner surfaces of steel pipes and after application, the difference in water consumption exceeds the total measurement error, which can be explained by an increase in the cross-sectional area of the pipes due to a decrease in the thickness of the boundary layer as a result of epilation of the inner surface of the pipes.

To test the proposed method upon receipt of the antifriction coating on open surfaces, a plant was manufactured, the structural-technological scheme of which is presented in Fig.2. Plates with a limiting size of 600 × 900 mm were used as the test object.

The installation consists of a receiver 1 with a capacity of 100 liters, connected by an inlet pipe to a compressor 2. An electromagnetic valve 3 is installed on the outlet pipe, an ejector device 4 for injecting and spraying epilame from a supply tank 5, a device 6 for twisting a two-phase gas and epilame stream, including a screw enclosed in a housing. A supersonic Laval 7 nozzle is intended for the formation of a directed jet. The installation includes an industrial heat dryer 10 with a power of 2 kW.

A Laval nozzle with a device for swirling the flow and a hair dryer are structurally combined into one block, mounted on a platform 14, which has the possibility of translational-reciprocal movement (scanning). The plate 15 is fixed with the possibility of linear movement perpendicular to the direction of movement of the specified block.

A computer is used to control the operation of the installation and the processing of the received data.

A method of obtaining an antifriction polymer coating on a flat surface of the product is implemented as follows.

The receiver 1 is filled with air, nitrogen or inert gas to a pressure of 8 atmospheres. The installation is brought into the “start” state, the industrial dryer 10 is turned on in the “heating” position, the valve 3 is opened, the platform 14 is brought into a scanning state and the plate 15 moves perpendicular to the movement of the platform. Scanning speeds and plate movements can vary from 10 to 100 mm / s.

During the operation of the installation, the surface of the plate is heated to a temperature of 50-70 ° C. Temperature control is carried out by a thermal imager. After opening valve 3, gas flows out of the receiver. In the process of gas outflow, the epilam is ejected from the supply tank 5 into the gas stream.

The two-phase gas and epilame stream created in the ejector 4 passes through the device for twisting the stream 6, consisting of a screw installed in the housing and connecting fittings, enters the Laval 7 supersonic nozzle 7. The supersonic two-phase jet flowing out of the nozzle collides with the heated plate surface.

For the presented installation, the gas flow rate can vary between 30-300 g / s, and the flow rate of the epilame introduced through the ejector into the flow can vary from 2-60 g / s.

Example 6

As a test object, a plate made of stainless steel X18H9T with a size of 200 × 400 mm and a thickness of 1 mm was selected.

On the plate, the surfaces of which were pre-treated with B-70 gasoline and dried at a temperature of 100-120 ° C, the Avtokon-0.5 epilums were applied according to the above procedure (see figure 2). The epilam was injected at a flow rate of 5 g / s with an ejector device 4 into a stream of nitrogen supplied with a flow rate of 30 g / s from receiver 1. The obtained two-phase flow, consisting of nitrogen and epilame, was twisted around the longitudinal axis by screw 6 and sent by supersonic nozzle 7 to plate surface 15. During the experiment, the plate moved at a speed of 20 mm / s, and the platform with a nozzle and a hairdryer moved along a translational-return trajectory at a speed of 50 mm / s. After applying epilam, the resulting coating was thermofixed for 30-90 minutes. The plate was epilated on both sides.

In order to assess the effect of the applied antifriction coating on the flow resistance of the plate on a hydrodynamic installation (Fig. 3), we studied the dependence of the flow resistance before epilating the plate and after, depending on the flow rate.

The installation consists of an open container 16 filled with water. Inside the tank, a water flow is organized with a flow rate that ensures the flow rate of the test plate 15 in the range from 1 m / s to 5 m / s. Water supply and discharge devices provide a uniform flow rate around the plate contour and a constant water level during the experiment. The plate is suspended on flexible tapes connected through strain gauges 17 and 18 with the upper support. To measure the resistance force of the plate when it is flowing around with water in a horizontal plane, the plate is connected through a flexible tape to the strain gauge 19. Measurement data by the strain gauges and the water flow rate necessary to calculate the velocity of the flow around the plate with water are transferred to a computer where the mathematical processing of the test results is performed.

The test results are presented in table 4.

According to the results of mathematical processing of the data obtained before coating the plate and after it is applied, the difference in resistance to flow around the plate exceeds the total measurement error, which can be explained by a decrease in the friction stress on the surface of the plate due to a change in the structure of the boundary layer as a result of epilation of the plate surfaces.

Using the proposed method allows to obtain antifriction polymer coatings with high tribological properties on the surface of products with large dimensions.

Table 1 No. of blades for examples Equivalent area of the channels of the blade, averaged over the results of 30 tests, before applying the antifriction coating, mm ² Equivalent area of the channels of the blade, averaged over the results of 30 tests, after applying an antifriction coating, mm ² Example 1 one 22.4 23.5 2 22.1 23.1 3 22.3 23,4 four 22.2 23.1 5 22.5 23.6 Example 4 one 22.4 22.8 2 22.1 22.5 3 22.3 22.7 four 22.2 22.6 5 22.5 22.9 Prototype one 22.4 22.7 2 22.1 22.4 3 22.3 22.5 four 22.2 22.5 5 22.5 22.8

table 2 No. of steel pipe by examples Equivalent area of pipe channels, averaged over the results of 30 tests, before applying anti-friction coating, mm ² Equivalent area of pipe channels, averaged over the results of 30 tests, after applying an antifriction coating, mm ² Example 2 one 224 235 2 221 231 3 223 234 four 222 231 5 225 236 Example 3 one 224 236 2 221 233 3 223 235 four 222 234 5 225 237 Example 5 one 224 235 2 221 232 3 223 233 four 222 231 5 225 236 Prototype one 224 228 2 221 226 3 223 228 four 222 227 5 225 229

Table 3 No. of pipe by examples Water consumption at a pressure at the inlet to the pipe 5 kgf / cm ² before applying the antifriction coating, g / s Water consumption at a pressure at the inlet to the pipe 5 kgf / cm ² after applying an antifriction coating, g / s Example 2 one 9390 9570 2 9320 9490 3 9350 9530 four 9360 9550 5 9380 9560 Example 3 one 9390 9610 2 9320 9520 3 9350 9600 four 9360 9620 5 9380 9630 Example 5 one 9390 9560 2 9320 9480 3 9350 9520 four 9360 9540 5 9380 9550 Prototype one 9390 9480 2 9320 9440 3 9350 9450 four 9360 9460 5 9380 9470

Table 4 Plate flow rate, m / s Resistance force when flowing around a plate before applying an antifriction coating on the surface of the plate, g The resistance force when flowing around a plate after applying an antifriction coating on the surface of the plate, g according to the invention prototype one 350 332 344 2 890 801 850 3 3200 2976 3060 four 5600 5152 5405 5 8750 7962 8360

Claims (4)

1. The method of obtaining a polymer antifriction coating on the surface of the product, including surface treatment with a cleaning agent, drying, applying to the surface of the epilam — an organofluorine surfactant solution (Fluorosurfactant) —perfluoropolyoxyalkylene or perfluorinated polyalkylene oxide compound with a directed gas flow, coating heat setting, characterized in that that after drying, the surface is additionally heated to a temperature exceeding the boiling point of epilam, application of a solution of FT p-surfactant is carried out by directed and swirling around its longitudinal axis a gas stream supplied with a flow rate of 30-300 g / s, with an epilame flow rate of 5-15 g / s, and a gas selected from the group consisting of air, nitrogen and inert gas. 2. The method according to claim 1, characterized in that the epilame is introduced into the gas stream by an ejector device. 3. The method according to claim 1, characterized in that the gas flow swirling around its longitudinal axis is created by means of a screw. 4. The method according to claim 1, characterized in that the directed gas flow is obtained using a supersonic nozzle.

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