RU2304764C1 - Method of evaluation of corrosion resistance of motor oils - Google Patents

Abstract

FIELD: chemical industry; petrochemical industry.

SUBSTANCE: method can be used for measuring level of corrosion resistance of motor oils and their differentiation at their leave for work and application. Content of copper and lead in oil to be analyzed is determined before oil makes contact with plate. Oil is poured into container. Plate is made of bearing alloy in form of segment of cylinder. Weight of plate is measured and plate is fixed above generator line of rotated shaft mounted in container. Plate is subject to effect of preset force; vector of force is perpendicular to axis of shaft. Material of internal surface of plate is brought into contact with analyzed oil during 2-6 hours while bubbling oil, plate and in between by air at preset temperatures. Changes in weight of plate and changes in content of copper and lead in oil are used as corrosion activity coefficients during testing.

EFFECT: improved truth of results; reduced labor input.

2 dwg, 1 tbl

Description

The invention relates to the field of analysis of materials, mainly motor oils (MM), in particular to the assessment of their corrosion activity (KA), and can be used in the chemical and petrochemical industry to determine the level of anticorrosion properties (PCS) of MM and their differentiation when admitted to production and application in technology.

One of the quality indicators of MM is a spacecraft characterizing their ability to interact with materials of the construction of machines and mechanisms, storage, transportation and refueling equipment.

Toughening environmental standards for the content of toxic components in exhaust gases, along with improving the technical and economic indicators of ICE, reducing oil consumption for waste and increasing the frequency of replacement of MM, requires a higher level of operational properties (ES) of MM.

For diesel engines, the use of turbocharging, the introduction of exhaust gas recirculation, increasing the fuel injection energy while reducing the angle of advance of the injection have a significant effect on the level of ES MM; for gasoline engines - distributed fuel injection over cylinders and operation on lean mixtures, changing geometry and valve timing. Low oil consumption during the operation of modern engines is due to the peculiarities of the flow of work processes and the optimization of the geometric parameters of the piston cylinder parts.

Changes in the design of modern engines and their operating conditions have led to an increase in the operating temperatures of parts and loads on them, an increase in the amount of soot in the oil (for diesel engines), an increase in the amount of gas escaping into the crankcase, a change in the chemical composition of the fuel combustion products, and, as a result, a premature decrease in the level a number of functional properties of the oil. Taking into account the factors listed above, qualitatively new requirements are also imposed on the level of PKS MM.

In contact with engine oil, metals can be destroyed (corroded) as a result of chemical or electrochemical processes on their surface [B.V. Belyanin, V.N. Erich, V.G. Korsakov. Technical analysis of oil products and gas. 5th edition, revised. L .: Chemistry, 1986, p.121-122].

The corrosive activity of oils is due to both their individual properties, depending on the chemical composition, and the conditions of their operation, under which the processes of chemical and electrochemical interaction of oils with the material of engine parts can occur. When assessing the corrosivity of oils, one of the characterizing indicators is the loss of mass of parts as a result of corrosion.

Since the interaction of oils with structural elements of engine systems is one of the most important issues in ensuring the operational reliability of equipment, special attention when assessing the level of ES oils is given to the study of corrosion properties. In practice, various test methods have been developed and are used, which are based on the determination of the weight loss of structural materials that have been in contact with oils under various operating conditions, from corrosion.

To determine the corrosion activity, bench testing methods on small-sized and full-sized engines are most often used, in which the conditions of the processes on the metal surface of engine parts during their interaction with MM under operating conditions are reproduced.

So, the method for determining the corrosion activity of MM on a single-cylinder ICM-40 installation is known and widely used, which includes the following operations: preparing the engine for testing (assembling the engine, installing new connecting rod bearings, adjusting units, running in the analyzed oil, draining the oil after running in) , pouring fresh oil in the amount of 0.5 kg, testing for 40 hours at a crankshaft rotation speed of 1500 rpm, crankcase oil temperature 120 ± 2 ° C, fuel consumption 0.67 ± 0.01 kg / h ( total fuel consumption is 45 kg) , and the subsequent assessment of corrosion activity by the weight loss of the set of connecting rod bearing shells (norm no more than 25 mg) and the condition of the working surfaces (visual assessment) [TU 38.401405-82 - Motor oils. The PCM-40 K method for evaluating the antioxidant properties and corrosion activity of oils].

There is also a known method for assessing washing, anticorrosion and anti-wear properties on a full-sized D-245 diesel engine, which includes preparing the engine for testing (engine assembly, installing new connecting rod bearings, adjusting nodes, running in the analyzed oil, draining after running in), filling in fresh oil in an amount of 25 kg, testing for 120 hours at a crankshaft rotation speed of 2200 rpm, crankcase oil temperature 115-120 ° C, fuel consumption - 15 kg / h (total fuel consumption is 2000 kg), and the subsequent assessment of corrosion Nost of weight loss kit connecting rod bearing inserts (optional component) and of the working surfaces (visual assessment) [MMC decision №540 / 1-11 from 28.01.91 g].

Common disadvantages of the known methods are:

long test times and high fuel consumption;

the test conditions do not allow reproducing the operating modes of modern ICEs, which reduces the reliability of the assessment of the spacecraft MM.

Along with motor methods, laboratory methods for determining corrosion activity are also used.

Thus, a known method for determining the corrosive activity of motor oils is that the test oils are poured into calibrated glass tubes and heated in an oil bath to a temperature of 140 ° C, metal plates are suspended above the tubes and, moving them using an electric motor and a crank mechanism up and down, periodically contact the plates with oil and air for 50 hours [GOST 5162-49 "Method for determination of corrosion (according to Pinkevich)].

This method has a long test duration and does not allow to reliably differentiate modern oils by their corrosion activity.

There is also a method for determining the corrosive activity of oils, which consists in the fact that the oil is heated to a temperature of 150 ° C when tested without additives and to 200 ° C when tested with oils, subjected to forced circulation with an air flow rate of 125 l / h through a reactor with motionlessly with metal samples, from the reactor the oil is fed through the central tube into the supply tank, where it is heated, and again fed into the circulation [USSR Author's Certificate No. 129872, cl. G01N 17/00, 1959].

The disadvantages of this method are that, due to the low degree of oil atomization, the rate of oil oxidation is low and, as a result, the amount of organic peroxides formed in this process, which are the main oxidizing agents in the corrosion of metals at high temperatures, is small. In addition, a significant part of the organic peroxides formed during the oxidation of oil is destroyed during forced circulation in the pumping system and does not interact with metal samples, and additives and other oil components inevitably adsorb on the walls of the circulation system. All this leads to distortions in the results of evaluating the corrosiveness of oils.

A known method for assessing the corrosivity of oils, the essence of which is that the metal plates are fixed on the axis and rotated in a chamber with a heated test oil in the presence of air and judged by the change in the weight of the plates of the corrosive activity of the oil, use alternating plates of lead and copper, rotation which are carried out around a horizontal axis with a frequency of 600-750 rpm, the oil temperature is selected at 155-170 ° C, and air is supplied to the chamber at a flow rate of 50-100 ml / min [USSR Author's Certificate No. 938102, cl. G01N 17/00, 33/26, 1982].

This method has low reliability due to the lack of the possibility of varying the temperature range of the test.

Closest to the invention in technical essence, the achieved positive effect and taken as a prototype is a method for assessing corrosion activity, which includes the preparation of metal plates (plates of lead 1 mm thick are marked, wiped with cotton wool moistened with benzene, dried for 1-3 minutes and polished to a shine with cloth, then washed in a porcelain bowl with benzene, transferred to filter paper, dried for 10-15 minutes in air at room temperature and weighed with an error of not more than 0.0002 g; then plates on chew on glass rods, which are inserted into the tubes of the holders), the preparation of the analyzed oil (the test oil sample is thoroughly mixed for 5-10 minutes in a bottle filled to 3/4 of its capacity, and 36.5 g of oil are taken into two reaction flasks) ), installation of a cartridge with reaction flasks fixed on an inclined axis into the oil bath of the DK-NAMI device (according to GOST 13371-67). The cassette with flasks rotates at a frequency of 16 rpm. During rotation, the test oil is heated to a temperature of 140 ° C, in the presence of air, the plates are periodically contacted with oil for 10 hours, after which the corrosion index X is determined in grams per square meter, which is calculated by the formula:

where m is the mass loss of the plate per test, g;

S is the surface of the plate, m ² .

Corrosion of the oil is calculated as the arithmetic average of the results of determining two indicators of corrosion in parallel tests, at X≤1 g / m ^{2 the} test oil is considered non-corrosive (no corrosion) [GOST 20502-75 - "Oils and additives to them. Method for determining corrosion"] .

The disadvantages of this method are the significant duration of the test (10 hours) and the low accuracy of the evaluation results of modern MM.

The technical result of the invention is to increase the accuracy and reliability of determining the spacecraft MM by ensuring that the test conditions correspond to the actual operating conditions of the engines while reducing labor costs by reducing the test time and the amount of analyzed oil.

The specified technical result is achieved by the fact that in the method for evaluating the spacecraft oils, including the interaction of a specially prepared metal plate with the analyzed oil at a given temperature for a given period of time in the presence of atmospheric oxygen and the subsequent assessment of the mass loss of the plate during the test, according to the invention, they are measured before contact with the plate the content of copper and lead in the analyzed oil, pour oil in an amount of 30 ml into the container in which the rotating shaft is installed, the plate is made of a bearing alloy in the form of a cylinder segment with a radius of curvature equal to the radius of the rotating shaft, fix it over the generatrix of the shaft in the upper part of the tank and press the plate to the shaft with a force of 24 ± 2 kgf, the vector of which is perpendicular to the axis of the shaft when the material of the inner surface of the plate interacts with the analyzed oil, which is carried out for 2-6 hours while sparging with air at the oil, plate and friction zone temperatures of 120 ± 10 ° С, 160 ± 10 ° С, 180 ± 10 ° С, respectively, at the end of the interaction of the plate with the analyzed m scrapped and measure the copper content of lead in the oil mass and the metal plate, and, as indicators of oil corrosivity using the difference of the measured parameters:

,

Δ M _PL = M-M ¹ ,

,

where ΔM _PL - change in plate mass per test, mg;

M is the initial mass of the plate before interacting with oil, mg;

M ¹ is the mass of the plate after the test, mg;

ΔM _Cu , ΔM _Pb - change in the content of Cu and Pb in the test oil per test, wt.%;

M _cu , M _Pb — Cu and Pb content in the oil before testing, wt.%;

,

- содержание Cu и Pb в масле после испытания, мас.%;

,

- the content of Cu and Pb in the oil after the test, wt.%;

which make up for oils

groups B -

6.95 <ΔM _PL ≤7.92 mg; ΔM _Cu = 0.0078-0.0098 wt.%; ΔM _Pb = 0.0031-0.0050 wt.%,

groups G -

5.17 <ΔM _PL ≤5.97 mg; ΔM _Cu = 0.0161-0.0184 wt.%; ΔM _Pb = 0.0078-0.0097 wt.%,

groups D -

3.22 <ΔM _PL ≤3.82 mg; ΔM _Cu = 0.0223-0.0243 wt.%; ΔM _Pb = 0.0108-0.013 0 wt.%.

Figure 1 presents the installation diagram for assessing the corrosion activity of MM (in the context);

figure 2 - a shaft with a plate (at the time of contact).

The installation consists of a container 1 filled with test oil 2, in the bottom of which a drain plug 3 is installed, a heater 4, a shaft 5 installed in the holes in the container 1 on two deep groove ball bearings 6, a plate 7 installed in a special socket 8, a rod 9, a compressor 10, the lower and upper fittings 11 and 12, respectively, and thermocouples 13, 14 and 15, thermostat 16.

The shaft 5 is installed so that its working surface, which is made of high alloy steel and cemented to a hardness of 58 HRC, is immersed in the test oil 2 to a depth of at least 10 mm (oil volume V _M is 30 ml). Plate 7 is a bearing alloy used for the manufacture of crankshaft bearings for YaMZ and KamAZ engines and has a width of L = 22 mm, an arc chord length of a = 16 mm, a thickness of h = 2.7 mm and a radius of curvature R equal to the radius of the shaft 5 R = Rv = 36 mm. The shape of the plate 7 simulates the shape of the bearing of the crankshaft.

The plate 7 is fixed on the inner side of the tank 1 (in a special socket 8) with the possibility of contacting with the working surface of the shaft 5 (figure 2), which is driven by an electric motor (not shown) with a rotation speed n _bp = 1390 rpm. A force of 24 ± 2 kG is applied to the plate 7 in the process of interaction with the test oil 2, which is created using a lever mechanism (not shown) through the rod 9. The load value of 24 ± 2 kG is selected based on the analysis of the loads on the bearings of the crankshaft of various engine modifications [ Safonov A.S., Ushakov A.I., Zolotev V.A. etc. Motor oils for automotive engines. Properties Classification. Assortment groups. - St. Petersburg, NPIKTS, 2004, p.6-9]. For air circulation in the tank 1, a compressor 10 is used, which is connected to the lower fitting 11. The air flow rate G _B is 20 l / h and is selected based on the analysis of the internal combustion engine working process. To measure the temperature of oil 2 T _m in the tank 1 and plate T _PL , as well as in the friction zone T _Tr equal to 120 ° C, 160 ° C, 180 ° C, thermocouples 13, 14 and 15, respectively, are used. The temperature of the oil 2 in the tank 1 is controlled by a thermocouple 13 and is supported by the temperature controller 16 (temperature meter-controller TPM 101). The temperature parameters of the tests were selected in accordance with the actual temperature zones of the internal combustion engine (zone C - up to 150 ° C, zone B - up to 200 ° C) [Safonov A.S., Ushakov A.I., Zolotev V.A. etc. Motor oils for automotive engines. Properties Classification. Assortment groups. - St. Petersburg, NPIKTS, 2004, p.6-9].

A method for assessing the corrosion activity of motor oils is implemented as follows.

Example: a prefabricated plate 7 is placed in a mechanical press to obtain a radius of curvature equal to the radius of the shaft 5. Plate 7 is ground with a GOI paste and using a magnifying glass, the presence of corrosion, stains, and other damage on its surface is evaluated. Then it is washed in a solvent, for example benzene, dried on filter paper and weighed to the nearest 0.0002 g. A certain mass of plate 7 is taken as the initial M = 7.6646 g.

In the oil sample M-10 D (m), the presence of copper and lead is determined by atomic absorption before testing M _Cu = 0, M _Pb = 0. In a measuring cylinder with a volume of 100 ml, 3/4 oil M-10 D (m) is poured into 3/4 and mixed thoroughly for 5-10 minutes, after which 30 ml is poured into a container 1. Install plate 7 in a special socket 8 on the working surface of the shaft 5 They turn on the unit’s power supply, compressor 15 for sparging oil with air and set the oil temperature 2 in the working tank 1 equal to 120 ° С, which is further controlled by thermocouple 13 and supported by temperature regulator 16, load plate 7 with a force of 24 ± 2 kgf.

After 4 hours, turn off the compressor 15, turn off the power to the unit, remove the plate 7 from the unit, wash it in benzene, dry it on filter paper and weigh it with an accuracy of 0.0002 g, the obtained mass value is taken for the mass of the plate 7 after the test M ¹ = 7 , 6289 g and calculate the indicator of corrosion activity according to the formula:

ΔM _PL = M-M ₁ = 7.6646-7.6289 = 0.0357 g (3.57 mg).

а затем рассчитывают изменение содержания металлов в масла после испытания:An oil sample M-10 D (m) is taken from the sump of the installation and the copper and lead contents are determined

and then calculate the change in the metal content in the oil after the test:

сравнивают полученные значения с экспериментально полученными величинами и делают вывод: анализируемое масло М-10 Д (м) по уровню коррозионной активности относится к группе Д.

compare the obtained values with the experimentally obtained values and conclude that the analyzed oil M-10 D (m) in terms of corrosion activity belongs to group D.

The claimed method was used to test samples of motor oils M-6 _Z / 10V, M-8V ₂ , M-8V, M-14V ₂ , M-10V, M-10G ₂ , M-8G ₂ , M-10G ₂ (k), M-5 _Z / 12G, M-6 _Z / 14G ₁ , M-10D (m), SAE 15W-30SF / CC, SAE 10W-40SF / CD, M-8D (m), M-8 D ₂ , ASR -Premium, SAE 10W-40SG / CF-4, SAE 15W-30SG, Shell Helix Plus, Mobil Delvac 1330. The main test results are shown in the table.

Test results for engine oil samples No. p / p Brand of oil Test conditions Main settings findings Measured Estimated M, g M ¹ , g ΔM _Cu , wt.% ΔM _Pb , wt.% ΔM ¹ _Cu , wt.% ΔM ¹ _Pb , wt.% ΔM _pl , mg ΔM _Cu , wt.% ΔM _Pb , wt.% one M-6 _Z / 10B






t _isp. = 4 hours
n _cr = 1390
min ^-1
R _B = 36 mm
V _M = 30 ml
T _M = 120 ° C
T _Tr = 160 ° C
T _mp =
180 ° C 7.6469 7.5731 0 0 0.0085 0.0039 7.38 0.0085 0.0039 to gr. AT 2 M-8V ₂ 7.6340 7.5626 0 0 0.0082 0.0034 7.14 0.0082 0.0034 to gr. AT 3 M-8V 7.6170 7.5475 0 0 0.0078 0.0031 6.95 0.0078 0.0031 to gr. AT four M-14V ₂ 7.6323 7.5571 0 0 0.0096 0.0043 7.52 0.0096 0.0043 to gr. AT 5 M-10V 7.6265 7.5473 0 0 0.0098 0.0050 7.92 0.0098 0.0050 to gr. AT 6 M-10G ₂ 7,6486 7.5920 0 0 0.0179 0.0091 5.66 0.0179 0.0091 to gr. R 7 M-8G ₂ 7.6512 7.5977 0 0 0.0167 0.0083 5,3 5 0.0167 0.0083 to gr. R 8 M-10G ₂ (k) 7.6218 7.5675 0 0 0.0171 0.0087 5.43 0.0171 0.0087 to gr. R 9 M-5 _Z / 12G 7.6183 7,5666 0 0 0.0161 0.0078 5.17 0.0161 0.0078 to gr g 10 M-6 _Z / 14G ₁ 7.6581 7.5984 0 0 0.0184 0.0097 5.97 0.0184 0.0097 to gr. R eleven M-10D (m) 7,6646 7,6289 0 0 0,0223 0.0126 3.57 0,0223 0.0126 to gr. D 12 SAE 15W-30SF / CC 7.6254 7,5904 0 0 0,0219 0.0124 3,50 0,0219 0.0124 to gr. D 13 SAE 10W-40SF / CD 7.6272 7.5890 0 0 0,0243 0.0130 3.82 0,0243 0.0130 to gr. D fourteen M-8D (m) 7.6322 7.5981 0 0 0.0232 0.0112 3.41 0.0232 0.0112 to city D fifteen M-8D ₂ 7.6526 7,6204 0 0 0,0227 0.0108 3.22 0,0227 0.0108 to gr. D 16 ASR-Premium 7.5740 7.5660 0 0 0,0295 0.0167 1.80 0,0295 0.0167 to gr. E 17 SAE 10W-40SG / CF-4 7.5967 7.5822 0 0 0,0269 0.0152 1,61 0,0269 0.0152 to gr. R. eighteen SAE 15W-30SG 7.6345 7.6184 0 0 0,0261 0.0148 1.45 0,0261 0.0148 to gr. N 19 Shell helix plus 7,6236 7.6069 0 0 0,0273 0.0157 1,67 0,0273 0.0157 to gr. N twenty Mobil Delvac 1330 7.5927 7,5752 0 0 0,0279 0.0161 1.75 0,0279 0.0161 to gr. N

Thus, the application of the invention will allow:

- to increase the accuracy and reliability of the assessment of the spacecraft level of modern MMs by approximating the test conditions (oil heating, using a bearing alloy plate, the implementation of the tribochemical oxidation of MM both in volume and directly in the friction unit) to the actual operating conditions of the engines;

- differentiate MM according to the level of spacecraft;

- reduce labor costs by reducing test time;

- reduce the amount of analyzed oil.

Claims (1)

A method for evaluating the corrosivity of oils, including the interaction of a specially prepared metal plate with the analyzed oil at a given temperature for a given period of time in the presence of atmospheric oxygen and a subsequent assessment of the mass loss of the plate during the test, characterized in that the copper and lead contents are measured before contact with the plate the analyzed oil, pour oil in an amount of 30 ml into the container in which the rotating shaft is installed, the plate is made of a bearing alloy in the form A cylinder segment with a radius of curvature equal to the radius of the rotating shaft, fix it over the shaft generatrix in the upper part of the tank and press the plate against the shaft with a force of 24 ± 2 kG, whose vector is perpendicular to the axis of the shaft when the material of the inner surface of the plate interacts with the analyzed oil, which is carried out in during 2-6 hours when sparging with air at oil, plate temperatures and in the friction zone equal to 120 ± 10 ° С, 160 ± 10 ° С, 180 ± 10 ° С, respectively, at the end of the interaction of the plate with the analyzed oil, the copper content is measured and intsa oily mass and the metal plate, and as the oil corrosivity performance difference of the measured parameters are used Δ M _PL = M-M ¹ ,

,

, where ΔM _PL - change in plate mass per test, mg; M is the initial mass of the plate before interacting with oil, mg; M ¹ is the mass of the plate after the test, mg; ΔM _Cu , ΔM _Pb - change in the content of Cu and Pb in the test oil per test, wt.% M _Cu , M _Pb - content of Cu and Pb in oil before testing, wt.%;

,

- the content of Cu and Pb in the oil after the test, wt.%, which make up for oils Group B 6.95 <ΔM _PL ≤7.92 mg; ΔM _Cu = 0.0078-0.0098 wt.%; ΔM _Pb = 0.0031-0.0050 wt.%; groups G 5.17 <ΔM _PL ≤5.97 mg; ΔM _Cu = 0.0161-0.0184 wt.%; ΔM _Pb = 0.0078-0.0097 wt.%; group D 3.22 <ΔM _PL ≤3.82 mg; ΔM _Cu = 0.0223-0.0243 wt.%; ΔM _Pb = 0.0108-0.0130 wt.%.

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