CN113355149B - Preparation method of anti-wear hydraulic oil - Google Patents

Abstract

The invention discloses a preparation method of anti-wear hydraulic oil, which comprises the following steps: (1) evaluating the comprehensive performance of various base oils, and selecting base oils with high comprehensive performance and reasonable price; (2) measuring the oil-water separation, the foam characteristic, the condensation point and the antirust performance of the base oil in the presence of water; (3) modification of base oil; (4) and (3) testing the friction performance: on a four-ball machine, testing the influence of the nano particles and the extreme pressure antiwear agent on the friction performance of the hydrogenated base oil, analyzing the microcosmic surface appearance of the wear-resistant spots and the types, valence states and contents of elements on the surfaces of the wear-resistant spots by adopting an optical profiler and a photoelectron spectrometer, researching the friction mechanism of the lubricating additive, and finding out a proper proportioning scheme; (5) and multi-stage wear-resistant hydraulic oil is developed. According to the invention, through an optimal proportioning scheme of the single-factor additive, various functional additives and a small amount of auxiliary additives are compounded, and the comprehensive performance of the hydraulic oil is improved.

Description

Preparation method of anti-wear hydraulic oil

Technical Field

The invention relates to the field of treatment of electric power systems and transformer oil, in particular to a preparation method of anti-wear hydraulic oil.

Background

With the development and the large-scale use of hydraulic machinery and the development of human beings to regions with severe environment, a hydraulic system faces more tests from a working environment, and therefore the requirement of the hydraulic system on hydraulic oil is higher and higher. The existing hydraulic oil can not completely meet the requirements of hydraulic machinery, so that the multi-stage wear-resistant hydraulic oil with higher comprehensive performance and reasonable price needs to be developed, so that the hydraulic oil has good lubricating performance and oxidation stability, and the service lives of the hydraulic oil and hydraulic elements are prolonged; meanwhile, the oil change frequency is reduced, the working efficiency of the hydraulic machine is improved, and the purposes of energy conservation and environmental protection are achieved. The hydraulic oil consumption in China is large, and the use cost of hydraulic machinery can be increased by importing more advanced multi-stage hydraulic oil in foreign countries; the domestic market is not common in multi-stage hydraulic oil, and the price is high, so that the multi-stage hydraulic oil cannot be widely used. The II-class and m-class hydroisomerized base oil which meets API standards is abundant in China, can produce multi-stage wear-resistant hydraulic oil which not only meets the high-pressure wear-resistant requirement, but also has good high-temperature and low-temperature performance and reasonable price, and has important significance for meeting the use requirements of various hydraulic machines such as agricultural machines, engineering machines, transportation machines and the like in China, saving energy and reducing environmental pollution.

Disclosure of Invention

Aiming at the technical problems in the prior art, the invention provides a preparation method of anti-wear hydraulic oil, which is realized by the following steps:

a preparation method of anti-wear hydraulic oil comprises the following steps: (1) the comprehensive performance of various base oils is evaluated, and the base oil with high comprehensive performance and reasonable price is selected, so that a foundation is laid for the development of the multistage hydraulic oil;

(2) measuring the oil-water separation property, the foam characteristic, the condensation point and the antirust performance of the base oil in the presence of water;

(3) modification of base oil: the antioxidant, the nano particles and the auxiliary additive are respectively added into the base oil in different proportions in a compounding manner, the influence of the viscosity modifier, the antioxidant, the nano particles and the auxiliary additive on the stability performance of the base oil is analyzed by testing the change of viscosity and acid value before and after oil product oxidation, the oil product is analyzed by infrared spectroscopy, and the proper compounding proportion of the viscosity modifier, the antioxidant, the nano particles and the auxiliary additive is determined, wherein the auxiliary additive is preferably di-n-butyl phosphite;

(4) and (3) testing the friction performance: on a four-ball machine, testing the influence of the nano particles and the extreme pressure antiwear agent on the friction performance of the hydrogenated base oil, analyzing the microcosmic surface appearance of the wear spots and the types, valence states and content of elements on the surface of the wear spots by using an optical profiler and a photoelectron spectrometer, researching the friction mechanism of the lubricating additive and finding out a proper proportioning scheme;

(5) developing multistage antiwear hydraulic oil: according to the optimal proportioning scheme of the single-factor additive, a plurality of functional additives and a small amount of auxiliary additives are compounded, and the comprehensive performance of the hydraulic oil is improved.

Preferably, the base oil is liquid paraffin; the nano particles are nano copper oxide particles.

Preferably, the nano copper oxide is obtained by the following process: step one, respectively taking 100ml of deionized water and absolute ethyl alcohol, mixing the deionized water and the absolute ethyl alcohol in a conical flask, stirring the mixture in a water bath at the constant temperature of 80 ℃, and simultaneously weighing 0.285g of stearic acid and adding the stearic acid into the system for full dissolution; secondly, weighing 0.62g of hydrazine hydrate, pouring the hydrazine hydrate into the mixed solution, and adjusting the pH value to 9 by using NaOH aqueous solution; thirdly, dissolving 2.0g of copper acetate into 50ml of deionized water, then dropwise adding the copper acetate solution into a conical flask, and violently stirring for 9 hours under the condition of 80 ℃ constant-temperature water bath, wherein the system gradually changes from light yellow to brown yellow and finally to rusty yellow; and fourthly, separating out solid particles by suction filtration, washing the solid particles with deionized water and absolute ethyl alcohol for three times respectively, and drying the obtained solid-phase substance under vacuum at 50 ℃ for 24 hours to prepare the stearic acid-coated copper oxide nanoparticles.

Preferably, in the step (3), the specific method for modifying the base oil by the copper oxide is as follows: adding liquid paraffin into the prepared copper oxide nanoparticles according to the mixture ratio of 0.05 percent, 0.10 percent, 0.15 percent and 0.20 percent of different mass fractions to prepare the compound lubricating oil, adopting a four-ball machine to carry out an anti-wear performance experiment on the lubricating grease, carrying out a friction performance test on the prepared oil product by the experiment, and obtaining the average value of each group of tests for three times as the final experiment result.

Preferably, the steel ball is a GCr15 steel ball with the diameter of 12.7mm, the four-ball machine comprises an upper cover, a base body, a rotating shaft, an upper steel ball and a lower steel ball, and under the loading condition, the upper steel ball rotates opposite to the lower three static steel balls of which the surfaces are coated with test grease; the structure diagram of the four-ball machine is shown in fig. 7, the friction element is composed of four steel balls, the lower three steel balls are clamped in the oil sample cup and tightly attached to each other, the upper steel ball is arranged, and sample oil in the oil sample cup needs to submerge the bottom ball during testing. The top ball above is driven by the main shaft to be fixed on the rotating shaft to rotate, and when the device runs, the three bottom balls below are jacked up under the action of upward load force to compress the top ball, so that a plurality of sliding modes of point contact between every two steel balls of 4 steel balls are formed. The test conditions in the test process can be adjusted, and under the condition that any test condition is changed, the friction force and the abrasion spot diameter between the steel balls are different.

Preferably, the additive amount of the nano copper oxide is 0.2%, and the content of the di-n-butyl phosphite is 0.6%.

Preferably, the water separability of oil and synthetic liquid is determined by charging 40mL of sample and 40mI. of distilled water in a measuring cylinder and stirring at 54 ℃ or 82 ℃ for 5min, and recording the time required for the emulsion to separate. After resting for 30min or 60min, if the emulsion did not separate completely, or the emulsion layer did not decrease to 3mL or less, then the volumes of the oil layer (or synthetic fluid), water layer, and emulsion layer at that time were recorded.

Preferably, the foam characteristics of the base oil are determined by blowing a sample at 24 ℃ for 5min with a constant flow of air and then standing for 10min, measuring the volume of foam in the sample at the end of each cycle, taking a second sample, testing at 93.5 ℃ and repeating the test at 24 ℃ when the foam has disappeared.

Preferably, the freezing point measuring method is that the sample is loaded in a specified test tube and cooled to the expected temperature, the test tube is inclined to the horizontal to be kept at 45 degrees for 1min, whether the liquid surface moves or not is observed, and the highest temperature that the liquid surface does not move is taken as the freezing point of the sample.

The rust inhibitive performance of the base oil in the presence of water is preferably tested by mixing 300ml of the sample with 30ml of water, immersing the entire cylindrical test steel bar therein, and stirring at 60 ℃ to determine suitability for periodic observation of rust.

Through experiments, the elements such as Fe, C, O, Cu and the like are distributed on the abrasion surface and are distributed in the abrasion area. Wherein the enrichment region of the Cu element is caused by a filling and repairing mechanism of the nano lubricating oil. Meanwhile, the 'complementary' effect of Cu and Fe elements is combined with a friction boundary lubricating film formed by the base oil under the high-speed heavy-load condition, so that the oil film strength between friction pairs is improved. Copper oxide nanoparticles, as lubricant additives, play an important role in the frictional contact area. Firstly, the copper oxide particles are filled and repaired in the surface furrows, so that the roughness of the grinding spots is improved to a certain extent, and the lubricating property is improved. More importantly, the copper oxide and the Fe are subjected to complementary film formation on the wear surface, so that the oil film strength is improved. The mechanism of the antifriction and antiwear performance of the nano copper oxide as the lubricating oil additive is shown.

Has the beneficial effects that:

(1) the hydraulic oil used as the additive has low toxicity, and the lubricating property and the wear resistance are obviously improved.

(2) Through the wear resistance test of a four-ball machine, the wear resistance of the basic hydraulic oil can be improved by the di-n-butyl phosphite, and an optimal numerical value exists.

(3) The stearic acid coated copper oxide nano-particles are used as a lubricating oil additive to obviously improve the tribological performance of the lubricating oil. Especially, the copper oxide nano-particles with the additive amount of 0.2 percent show the best friction-reducing and wear-resisting lubricating effect. When the content of the additive is 0.2%, the reduction range of the friction coefficient reaches 30.0%, and the reduction range of the abrasion spot diameter reaches 47.6%.

(4) The mechanism of adding the copper oxide nano-particles for friction reduction and wear resistance is that under the condition of high speed and heavy load, copper oxide is complemented with Fe on the surface of a friction pair to form a layer of chemical reaction film which is easy to shear, so that the direct contact wear of the friction pair is avoided, and the surface of the friction pair is filled and repaired to achieve the effects of friction reduction and wear resistance.

Drawings

FIG. 1 is a flow chart of a process for preparing an antiwear additive for hydraulic oil;

FIG. 2 is a graph of the effect of copper oxide content on coefficient of friction (COF) and Wear Scar Diameter (WSD);

FIG. 3 is a graph of wear surface topography for different lubricating media;

FIG. 4 is a graph of the analysis of elements of a wear surface using an energy dispersive X-ray spectrometer;

FIG. 5 is a graph of wear surface element content;

FIG. 6 is a graph of data from T304 experiments at various levels;

fig. 7 is a schematic structural diagram of a four-ball machine.

Reference numerals: the steel ball bearing comprises an upper cover 1, a seat body 2, a rotating shaft 3, an upper steel ball 4 and a lower steel ball 5.

Detailed Description

In the following, the technical solutions in the embodiments of the present invention will be described in an entering and exiting manner and in a complete description, it is obvious that the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments, and based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts belong to the protection scope of the present invention.

The preparation method of the anti-wear hydraulic oil is realized by the following steps:

as shown in fig. 1-7, a preparation method of anti-wear hydraulic oil selects liquid paraffin as base oil; modifying the base oil by using the copper oxide nanoparticles; the nano particles are nano copper oxide particles, and the prepared copper oxide nano particles are added with liquid paraffin according to the mixture ratio of 0.05 percent, 0.10 percent, 0.15 percent and 0.20 percent of different mass fractions to prepare the composite lubricating oil. The formulated oil was tested for friction properties using a western ball mill (as shown in fig. 7). The steel ball used is a GCr15 steel ball with the diameter of 12.7mm, and the average value of each group of the steel balls is obtained by three tests and is used as the final experiment result.

The wear-leveling diameter size and the friction coefficient of copper oxide nanoparticles formed by different additive amounts shown in fig. 2 have similar variation trends. It can be seen that the addition of a small amount of copper oxide nanoparticles improves the anti-wear and anti-friction properties of the lubricating oil. When the mass fraction is 0.2%, the minimum friction coefficient of 0.098 and the minimum wear-scar diameter of 540 mu m are generated, the friction coefficient is reduced by 30.0%, and good antifriction and lubrication performances are displayed. Meanwhile, the reduction of the diameter of the abrasion wear spot reaches 47.6%, and the abrasion wear resistance is good. However, when the concentration of the nano copper oxide is further increased to 0.25-0.30%, the friction coefficient and the steel ball wear scar diameter are increased. This indicates that an excessive amount of nanoparticles is not advantageous to improve the lubricating properties of the base oil. The reason for this is mainly that the agglomeration of nanoparticles is aggravated, which has a certain side effect on lubrication.

After the frictional wear test was completed, the four balls were removed and subjected to ultrasonic cleaning for 30 minutes, followed by drying, SEM and EDS elemental analysis. FIG. 3 shows a friction pair GCr under different lubrication medium conditions₁₅The surface appearance of the grinding trace of the steel ball. a. b respectively corresponding to the wear surface appearance of the steel ball under the lubrication condition of pure liquid paraffin and liquid paraffin added with 0.2 percent of copper oxide nano particles. As shown in the graph a, the low viscosity of the liquid paraffin does not effectively prevent severe abrasion in the process of the friction pair contact, so that the abrasion spot diameter of the steel ball is causedLarger and create larger furrows, pits, and deep scratches. As can be seen from the graph b, the diameter of the abrasion spot is significantly reduced by adding 0.2% of the nano copper oxide particles, the surface of the abrasion spot is smooth, and no obvious furrows or pits are formed. In conclusion, the nano copper oxide shows good abrasion resistance as an additive.

In order to further analyze specific elements on the surface of the abrasive spot, an energy dispersion X-ray spectrometer is used for element analysis, the content of elements on the surface of the abrasive spot containing the copper oxide additive is analyzed as shown in FIG. 4, the content of each element is shown in FIG. 5, and the abrasion surface elements of the friction pair mainly comprise Fe, C, O and Cu. The experiment results in: the composite lubricating oil added with the nano copper oxide particles is subjected to a tribochemical reaction, and a boundary lubricating film containing elements such as Fe, C, Cu and the like is generated on the surface of a friction pair, which is the key point of the friction reduction and wear resistance of the nano copper oxide serving as a lubricating oil additive.

As shown in fig. 4 to 5, the elements such as Fe, C, O, and Cu are distributed over the wear region on the wear surface. Wherein, the enrichment area of the Cu element is caused by a filling and repairing mechanism of the nanometer lubricating oil. Meanwhile, the 'complementary' effect of Cu and Fe elements is combined with a friction boundary lubricating film formed by the base oil under the high-speed heavy-load condition, so that the oil film strength between friction pairs is improved. Copper oxide nanoparticles, as lubricant additives, play an important role in the frictional contact area. Firstly, the copper oxide particles are filled and repaired in the surface furrows, so that the roughness of the grinding spots is improved to a certain extent, and the lubricating property is improved. More importantly, the copper oxide and the Fe are complementarily formed into a film on the worn surface, and the oil film strength is improved. The mechanism of the wear-reducing and wear-resisting performance of the nano copper oxide as the lubricating oil additive is shown.

Selection of auxiliary addition:

the method comprises the steps of firstly, selecting HL hydraulic oil, determining the optimal addition amount of di-n-butyl phosphite (T304) through a small-scale test, and improving the wear resistance on the premise of not influencing other indexes of the hydraulic oil. The specific method comprises the following steps: when a certain amount of hydraulic oil is added into the oil according to the mass fraction of 0.30%, the diameter of the wear-resisting spot is 0.832mm, and when the mass fraction is 0.50%, the diameter of the wear-resisting spot is 0.614mm, so that the wear resistance is obviously improved. As can be seen from FIG. 7, the anti-wear performance is greatly improved with the increase of the amount of T304, and the optimum additive amount is determined by comparing the indexes of rust, foam resistance and the like through continuing tests. From FIG. 7, it can be analyzed that as the wear scar diameter decreases, the cleanliness and the demulsification are improved, and according to the change of the test data, the addition amount of T304 is 0.60% which is most suitable.

Various modifications and changes may occur to those skilled in the art. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. The above embodiments are provided only for illustrating the present invention and not for limiting the present invention, and those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and therefore all equivalent technical solutions should also fall within the scope of the present invention, and should be defined by the claims.

Claims (9)

1. The preparation method of the anti-wear hydraulic oil comprises the following steps: (1) evaluating the base oil, and selecting the base oil; (2) measuring the oil-water separation property, the foam characteristic, the condensation point and the antirust performance of the base oil in the presence of water; (3) modification of base oil: respectively adding an antioxidant, nanoparticles and an auxiliary additive into base oil, analyzing the influence of a viscosity regulator, the antioxidant, the nanoparticles and the auxiliary additive on the stability of the base oil by testing the change of viscosity and acid value before and after oil oxidation, and determining the compounding ratio of the viscosity regulator, the antioxidant, the nanoparticles and the auxiliary additive by analyzing the oil through infrared spectroscopy; (4) and (3) testing the friction performance: on a four-ball machine, testing the influence of the nano particles and the extreme pressure antiwear agent on the friction performance of the hydrogenated base oil, analyzing the microcosmic surface appearance of the wear-resistant spots and the types, valence states and contents of elements on the surfaces of the wear-resistant spots by using an optical profiler and a photoelectron spectrometer, researching the friction mechanism of the lubricating additive, and finding out a proportioning scheme; (5) the preparation of the antiwear hydraulic oil: compounding an additive and an auxiliary additive according to a single-factor additive proportioning scheme; the base oil is liquid paraffin; the nano particles are nano copper oxide particles; the copper oxide nanoparticles are obtained by: step one, respectively taking 100ml of deionized water and absolute ethyl alcohol, mixing the deionized water and the absolute ethyl alcohol in a conical flask, stirring the mixture in a water bath at a constant temperature of 80 ℃, and simultaneously weighing 0.285g of stearic acid to be added into a system for full dissolution; secondly, weighing 0.62g of hydrazine hydrate, pouring into the mixed solution, and adjusting the pH value to 9 by using NaOH aqueous solution; thirdly, dissolving 2.0g of copper acetate into 50ml of deionized water, then dropwise adding the copper acetate solution into a conical flask, and violently stirring for 9 hours under the condition of 80 ℃ constant-temperature water bath, wherein the system gradually changes from light yellow to brown yellow and finally to rusty yellow; and fourthly, separating out solid particles by suction filtration, washing the solid particles with deionized water and absolute ethyl alcohol for three times respectively, and drying the obtained solid-phase substance under vacuum at 50 ℃ for 24 hours to prepare the stearic acid-coated copper oxide nanoparticles.

2. The process for preparing an antiwear hydraulic fluid according to claim 1, wherein: the auxiliary additive is di-n-butyl phosphite.

3. The process for producing an antiwear hydraulic fluid according to any one of claims 1 or 2, wherein: in the step (3): adding liquid paraffin into the prepared copper oxide nanoparticles according to the mixture ratio of 0.05 percent, 0.10 percent, 0.15 percent and 0.20 percent of different mass fractions to prepare the compound lubricating oil, adopting a four-ball machine to carry out an anti-wear performance experiment on the lubricating grease, carrying out a friction performance test on the prepared oil product by the experiment, and obtaining the average value of each group of tests for three times as the final experiment result.

4. The process for preparing an antiwear hydraulic fluid according to claim 3, wherein: the four-ball machine comprises an upper cover (1), a base body (2), a rotating shaft (3), an upper steel ball (4) and a lower steel ball (5), wherein the steel ball is GCr₁₅Steel balls, 12.7mm in diameter, with the upper one rotating against the lower three stationary balls coated with test grease on their surfaces under load.

5. The process for preparing an antiwear hydraulic fluid as claimed in claim 2, wherein: the additive amount of the nano copper oxide is 0.2%, and the content of the di-n-butyl phosphite is 0.6%.

6. The process for producing an antiwear hydraulic fluid according to any one of claims 4 or 5, wherein: the oil-water separation method of base oil comprises charging 40mL sample and 40mI distilled water into a measuring cylinder, stirring at 54 deg.C or 82 deg.C for 5min, and recording the time required for emulsion separation; after resting for 30min or 60min, if the emulsion did not separate completely, or the emulsion layer did not decrease to 3mL or less, then the volume of the oil, water and emulsion layers at this time was recorded.

7. The process for preparing an antiwear hydraulic fluid of claim 6, wherein: the foam properties of the base oil were determined by blowing the sample at 24 ℃ for 5min with air at a constant flow rate and then standing for 10min, measuring the volume of foam in each sample at the end of each cycle, taking a second sample, testing at 93.5 ℃ and repeating the test at 24 ℃ when the foam had disappeared.

8. The process for preparing an antiwear hydraulic fluid of claim 7, wherein: the freezing point determination method comprises the steps of loading a sample in a specified test tube, cooling the test tube to a desired temperature, inclining the test tube to be horizontal and standing the test tube for 1min at an angle of 45 degrees, observing whether a liquid surface moves, and taking the highest temperature at which the liquid surface does not move as the freezing point of the sample.

9. The method for preparing an antiwear hydraulic fluid according to claim 8, wherein: the rust-preventive property test method of the base oil in the presence of water is to mix a 300ml sample with 30ml water, immerse the whole cylindrical test steel bar in the mixture, stir the mixture at 60 ℃ and determine that the rust-preventive property is suitable for periodic observation.

Images