High-temperature-resistant composite lubricating grease as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of lubricating grease, and particularly relates to high-temperature-resistant composite lubricating grease as well as a preparation method and application thereof. The high-temperature-resistant composite lubricating grease provided by the invention is prepared from the following components in percentage by mass: 85 to 98.5 percent of calcium sulfonate-based lubricating grease, 1 to 10 percent of nano calcium carbonate particles and 0.5 to 5 percent of layered graphite, the calcium sulfonate-based lubricating grease is prepared from the following raw materials in parts by mass: 21 to 22 parts of base oil, 21 to 22 parts of high-base-number calcium sulfonate, 0.4 to 0.5 part of short-chain alcohol, 0.4 to 0.5 part of acid transforming agent, 1.4 to 1.5 parts of 12-hydroxystearic acid and 2.4 to 2.5 parts of water, the average particle size of the nano calcium carbonate particles is 30 to 80 nm, and the mesh number of the layered graphite is 1200 to 10000. The composite lubricating grease provided by the invention has an excellent lubricating effect under high temperature and high load (80 DEG C, 500N).

Description

Technical Field

[0001] The present invention belongs to the technical field of greases, and particularly relates to a high-temperature resistant composite grease and its preparation method and application. Background Art

[0002] The friction pairs of rolling bearings specialized in the steel industry inevitably work under conditions of high load, high temperature, low rotational speed and instantaneous impact load, thus generating boundary lubrication. Continuous and good lubrication is the key to ensuring the normal operation of bearings under these complex working conditions. Calcium sulfonate-based grease has become an important solution for boundary lubrication on the bearing surface due to its excellent wear resistance, and has gradually replaced traditional soap-based greases and is widely used. However, in some special applications, under the condition of continuous high temperature, the calcium sulfonate-based grease will inevitably have the phenomena of thinning of the oil film and leakage loss, resulting in the boundary film being unable to continuously protect the bearing surface. Summary of the Invention

[0003] In view of this, the present invention provides a high-temperature resistant composite grease and its preparation method and application. The composite grease provided by the present invention has good high-temperature resistance and excellent lubrication effect under the working conditions of high temperature and high load.

[0004] In order to solve the above technical problems, the present invention provides a high-temperature resistant composite grease, which comprises the following components in mass percentage:

[0005] Calcium sulfonate-based grease 85 - 98.5%;

[0006] Nano calcium carbonate particles 1 - 10%;

[0007] Lamellar graphite 0.5 - 5%;

[0008] The calcium sulfonate-based grease comprises the following preparation raw materials in parts by mass:

[0009]

[0010] The average particle size of the nano calcium carbonate particles is 30 - 80 nm, and the mesh number of the lamellar graphite is 1200 - 10000 mesh.

[0011] Preferably, it comprises the following components in mass percentage:

[0012] Calcium sulfonate-based grease 92 - 97%;

[0013] Nano calcium carbonate particles 2 - 6%;

[0014] Lamellar graphite 1 - 2%.

[0015] Preferably, the base oil comprises one or more of mineral oil, polyalpha-olefin oil and ester oil;

[0016] The total base number of the overbased calcium sulfonate is 400-450 mgKOH / g;

[0017] The short-chain alcohol includes methanol, isopropanol, n-butanol or pentanol;

[0018] The acid conversion agent includes low-molecular-weight acid or dodecylbenzenesulfonic acid, and the low-molecular-weight acid includes acetic acid, propionic acid, boric acid or phosphoric acid.

[0019] The present invention also provides a preparation method of the high-temperature resistant composite grease described in the above technical solution, including the following steps:

[0020] Mix the overbased calcium sulfonate, nano calcium carbonate particles, 12-hydroxystearic acid and part of the base oil for the first time to obtain a first mixture;

[0021] Mix the first mixture, short-chain alcohol, acid conversion agent and water for the second time to carry out a saponification reaction to obtain a second mixture;

[0022] Mix the second mixture and the remaining base oil for the third time and then carry out dehydration and alcohol removal to obtain a third mixture;

[0023] After refining the third mixture, mix it with layered graphite for the fourth time to obtain the high-temperature resistant composite grease.

[0024] Preferably, the mass percentage of the part of the base oil in the total amount of the base oil is 40-50%;

[0025] The temperature of the first mixing is 70-80 °C, and the time is 30-60 min.

[0026] Preferably, the temperature of the saponification reaction is 80-90 °C, and the time is 30-60 min.

[0027] Preferably, the temperature of the third mixing is 80-90 °C;

[0028] The temperature of the dehydration and alcohol removal is 100-110 °C, and the time is 90-120 min.

[0029] Preferably, the temperature of the refining is 160-170 °C, and the heat preservation time of the refining is 10-15 min.

[0030] Preferably, the temperature of the fourth mixing is 80-90 °C;

[0031] After the fourth mixing, it further includes: filtering, homogenizing and degassing the system after the fourth mixing in sequence to obtain the high-temperature resistant composite grease.

[0032] The present invention also provides an application of the high-temperature resistant composite grease described in the above technical solution or the high-temperature resistant composite grease prepared by the preparation method described in the above technical solution in a rolling bearing.

[0033] The present invention provides a high-temperature resistant composite grease, which comprises components with the following mass percentages: 85-98.5% of calcium sulfonate-based grease, 1-10% of nano calcium carbonate particles, and 0.5-5% of lamellar graphite; the calcium sulfonate-based grease comprises the following raw materials for preparation in parts by mass: 21-22 parts of base oil, 21-22 parts of overbased calcium sulfonate, 0.4-0.5 part of short-chain alcohol, 0.4-0.5 part of acid conversion agent, 1.4-1.5 parts of 12-hydroxystearic acid, and 2.4-2.5 parts of water; the average particle size of the nano calcium carbonate particles is 30-80 nm, and the mesh number of the lamellar graphite is 1200-10000 mesh. In the present invention, a hydrogen bond aggregate is formed between 12-hydroxystearic acid and basic calcium sulfonate, and this hydrogen bond aggregate can form a network thickening structure to adsorb the base oil therein, and wrap the nano calcium carbonate particles to form a lubricating oil film with higher strength, improving its anti-wear and friction reduction effects. The high-temperature resistant composite grease provided by the present invention has excellent lubricating effects under high temperature and high load (80 °C, 500 N), solves the problem of abnormal increase in the friction coefficient in the initial running-in stage, reduces the friction coefficient in the running-in stage, and reduces the wear amount of the steel-steel friction pair. Description of the Drawings

[0034] Figure 1 SEM image of the nano calcium carbonate particles with a particle size of 50 nm used in the examples;

[0035] Figure 2 SEM image of the lamellar graphite with a mesh number of 5000 used in the examples;

[0036] Figure 3 Graph showing the relationship between the friction coefficient and time for Examples 1 and Comparative Examples 1-3;

[0037] Figure 4 Three-dimensional photographs of the test discs after the friction coefficient tests for Examples 1 and Comparative Examples 1-3;

[0038] Figure 5 Columnar comparison chart of the wear volumes of the test discs after the friction coefficient tests for Examples 1 and Comparative Examples 1-3. Detailed Embodiments

[0039] The present invention provides a high-temperature resistant composite grease, which comprises components with the following mass percentages:

[0040] Calcium sulfonate-based grease 85-98.5%;

[0041] Nano calcium carbonate particles 1-10%;

[0042] Layered graphite: 0.5 - 5%;

[0043] The calcium sulfonate - based grease includes the following raw materials in parts by mass for preparation:

[0044]

[0045]

[0046] The average particle size of the nano - calcium carbonate particles is 30 - 80 nm, and the mesh number of the layered graphite is 1200 - 10000 mesh.

[0047] In the present invention, unless otherwise specified, the raw materials used are all conventional commercially available products.

[0048] By mass percentage, the high - temperature resistant composite grease provided by the present invention includes 85 - 98.5% of calcium sulfonate - based grease, which can be 90 - 98%, or can also be 92 - 97%. By mass parts, the calcium sulfonate - based grease includes 21 - 22 parts of base oil, which can specifically be 21 parts or 22 parts. As a specific embodiment of the present invention, the base oil can include one or several of mineral oil, polyalpha - olefin oil, and ester oil, and can specifically be mineral oil, polyalpha - olefin oil, or ester oil; the mineral oil can be 150BS mineral oil, and the kinematic viscosity of the mineral oil can be 450 - 470 mm 2 / s; the polyalpha - olefin oil can be PAO40 synthetic oil, and the kinematic viscosity of the polyalpha - olefin oil can be 410 - 430 mm 2 / s; the ester oil can be trimellitic anhydride ester synthetic ester oil, and the kinematic viscosity of the ester oil can be 315 - 320 mm 2 / s.

[0049] Based on the mass parts of the base oil, the calcium sulfonate - based grease includes 21 - 22 parts of over - based calcium sulfonate, which can specifically be 21 parts or 22 parts. As a specific embodiment of the present invention, the total base number of the over - based calcium sulfonate can be 400 - 450 mgKOH / g, and can specifically be 400 mgKOH / g, 410 mgKOH / g, 420 mgKOH / g, 430 mgKOH / g, 440 mgKOH / g, or 450 mgKOH / g.

[0050] Based on the mass parts of the base oil, the calcium sulfonate - based grease includes 0.4 - 0.5 parts of short - chain alcohol, which can specifically be 0.4 parts or 0.5 parts. As a specific embodiment of the present invention, the short - chain alcohol can include methanol, isopropanol, n - butanol, or pentanol.

[0051] Based on the mass parts of the base oil, the calcium sulfonate grease includes 0.4 to 0.5 parts of an acid conversion agent, which can specifically be 0.4 parts or 0.5 parts. As a specific embodiment of the present invention, the acid conversion agent may include a low molecular weight acid or dodecylbenzenesulfonic acid, and the low molecular weight acid may include acetic acid, propionic acid, boric acid or phosphoric acid; the acetic acid may be glacial acetic acid.

[0052] Based on the mass parts of the base oil, the calcium sulfonate grease includes 1.4 to 1.5 parts of 12-hydroxystearic acid, which can specifically be 1.4 parts or 1.5 parts. As a specific embodiment of the present invention, the 12-hydroxystearic acid may be industrial grade. In the present invention, 12-hydroxystearic acid, as an organic fatty acid, contains H + , and can react with calcium carbonate in overbased calcium sulfonate to obtain calcium 12-hydroxystearate; the long carbon chain in calcium 12-hydroxystearate can improve the thickening ability of the grease and at the same time improve the high temperature resistance of the grease.

[0053] Based on the mass parts of the base oil, the calcium sulfonate grease includes 2.4 to 2.5 parts of water, which can specifically be 2.4 parts or 2.5 parts.

[0054] By mass percentage, the high temperature resistant composite grease provided by the present invention includes 1 to 10% nano calcium carbonate particles, which can be 2 to 8%, and can also be 2 to 6%. As a specific embodiment of the present invention, the average particle size of the nano calcium carbonate particles is 30 to 80 nm, which can specifically be 30 nm, 40 nm, 50 nm, 60 nm, 70 nm or 80 nm. In the present invention, the proportion of surface atoms in the nano calcium carbonate particles to the total number of atoms increases sharply, and the surface energy of the particles is relatively high, which can quickly form an adsorption film on the metal surface and can quickly play a lubricating effect when the friction pair comes into contact. The present invention limits the average particle size of the nano calcium carbonate to 30 to 80 nm, which is beneficial to the formation of a thin film lubricating layer, and the film thickness range of the thin film lubricating layer is 10 to 100 nm; the thin film lubricating layer forms a fluid lubricating film by the dynamic pressure effect generated by the relative movement of the friction surface, and at the same time, under the action of the surface effect, it is applicable to high-precision friction pairs under heavy load conditions.

[0055] By mass percentage, the high-temperature resistant composite grease provided by the present invention comprises 0.5 to 5% of lamellar graphite, which can be 0.8 to 4%, or can also be 1 to 2%. As a specific embodiment of the present invention, the mesh number of the lamellar graphite is 1,200 to 10,000 mesh, and can specifically be 1,200 mesh, 1,300 mesh, 1,500 mesh, 2,000 mesh, 3,000 mesh, 4,000 mesh, 5,000 mesh, 6,000 mesh, 7,000 mesh, 8,000 mesh, 9,000 mesh or 10,000 mesh. The present invention limits the mesh number range of the flaky graphite within 1,200 to 10,000 mesh, which is beneficial to the formation of a hydrodynamic lubrication layer, can be applicable to surface contact friction pairs at various speeds, and reduces the sliding friction coefficient. Lamellar graphite is a non-oil-soluble inorganic solid additive, which has excellent thermal stability and extreme pressure anti-wear properties, can improve the load-bearing performance of the grease, especially in the case of sliding and impact loads, can form a lamellar lubricating film under high loads; when the load increases, the lamellar graphite spreads to the surface of the friction pair, which can improve the load-bearing capacity of the oil film. The present invention uses calcium sulfonate-based grease as the base grease, introduces nano-calcium carbonate particles and lamellar graphite, solves the problems of large wear and easy jamming of rolling bearings under high temperature and high load, improves the extreme pressure anti-wear performance and friction reduction and lubrication performance, and at the same time improves the grease stability and sealing performance at high temperature.

[0056] The present invention also provides a preparation method of the high-temperature resistant composite grease described in the above technical solution, comprising the following steps:

[0057] Mix high-base calcium sulfonate, nano-calcium carbonate particles, 12-hydroxystearic acid and part of the base oil for the first time to obtain a first mixture;

[0058] Mix the first mixture, short-chain alcohol, acid conversion agent and water for the second time to carry out a saponification reaction to obtain a second mixture;

[0059] Mix the second mixture and the remaining base oil for the third time and then carry out dehydration and alcohol removal to obtain a third mixture;

[0060] Refine the third mixture and then mix it with lamellar graphite for the fourth time to obtain the high-temperature resistant composite grease.

[0061] The present invention first mixes overbased calcium sulfonate, nano calcium carbonate particles, dodecahydroxy stearic acid and a part of base oil to obtain a first mixture. As a specific embodiment of the present invention, the mass percentage of the part of base oil in the total amount of base oil can be 40-50%, specifically 40%, 42%, 44%, 45%, 48% or 50%. As a specific embodiment of the present invention, the temperature of the first mixing can be 70-80°C, specifically 70°C, 73°C, 75°C, 78°C or 80°C; the time of the first mixing can be 30-60 min, specifically 30 min, 40 min, 50 min or 60 min.

[0062] In the present invention, first mixing nano calcium carbonate particles with overbased calcium sulfonate, dodecahydroxy stearic acid and a part of base oil is conducive to the uniform dispersion of nano calcium carbonate particles in the complex grease, avoiding the uneven dispersion of nano calcium carbonate particles due to aggregation in the viscous calcium sulfonate-based grease.

[0063] After obtaining the first mixture, the present invention second mixes the first mixture, short-chain alcohol, acid conversion agent and water to carry out a saponification reaction to obtain a second mixture. The present invention has no special requirements for the second mixing, as long as they can be mixed evenly. As a specific embodiment of the present invention, the temperature of the saponification reaction can be 80-90°C, specifically 80°C, 83°C, 85°C, 88°C or 90°C; the time of the saponification reaction can be 30-60 min, specifically 30 min, 35 min, 40 min, 45 min, 50 min, 55 min or 60 min.

[0064] In the present invention, water serves as a medium to provide a reaction site for the saponification reaction, and short-chain alcohol acts as a catalyst. The acid conversion agent reacts with dodecahydroxy stearic acid and overbased calcium carbonate to convert the calcium carbonate crystal, and the reaction system becomes viscous after the reaction.

[0065] After obtaining the second mixture, the present invention third mixes the second mixture and the remaining base oil and then carries out dehydration and alcohol removal to obtain a third mixture. As a specific embodiment of the present invention, the temperature of the third mixing can be 80-90°C, specifically 80°C, 83°C, 85°C, 88°C or 90°C. As a specific embodiment of the present invention, the temperature of the dehydration and alcohol removal can be 100-110°C, specifically 100°C, 105°C or 110°C; the time of the dehydration and alcohol removal can be 90-120 min, specifically 90 min, 95 min, 100 min, 105 min, 110 min, 115 min or 120 min.

[0066] The present invention adds the remaining base oil to the viscous second mixture to dilute it for facilitating subsequent reactions.

[0067] After obtaining the third mixture, the present invention refines the third mixture and then mixes it with layered graphite for the fourth time to obtain the high-temperature resistant composite grease. As a specific embodiment of the present invention, the temperature of the refining can be 160-170 °C, specifically 160 °C, 165 °C or 170 °C; the heat preservation time of the refining can be 10-15 min, specifically 10 min, 12 min or 15 min.

[0068] Through refining, the present invention can further dehydrate and remove the moisture adsorbed in the network structure, ensuring the structural stability of the thickening network in the grease.

[0069] As a specific embodiment of the present invention, the temperature of the fourth mixing can be 80-90 °C, specifically 80 °C, 85 °C or 90 °C; the time of the fourth mixing can be 20-40 min, specifically 20 min, 25 min, 30 min, 35 min or 40 min.

[0070] As a specific embodiment of the present invention, after the fourth mixing, it may further include: filtering, homogenizing and degassing the system after the fourth mixing to obtain the high-temperature resistant composite grease. The present invention has no special limitation on the filtering, homogenizing and degassing, and the conventional methods in the art can be adopted.

[0071] In the early stage of the preparation process of the calcium sulfonate-based grease, the present invention adds nano-calcium carbonate particles, which is beneficial to the dispersion of nano-calcium carbonate in the calcium sulfonate micelles. At the same time, the reaction of 12-hydroxystearic acid is faster, and the corresponding carboxylate fibers and basic calcium sulfonate can form a hydrogen bond aggregate. This hydrogen bond aggregate can form a certain network thickening structure, adsorb the base oil therein, and form a lubricating oil film with higher strength. The nano-calcium carbonate encapsulated therein plays an anti-wear and friction-reducing role. The preparation method provided by the present invention is simple and efficient, can effectively reduce the production energy consumption and shorten the production time.

[0072] The present invention also provides the application of the high-temperature resistant composite grease described in the above technical solution or the high-temperature resistant composite grease prepared by the preparation method described in the above technical solution in rolling bearings.

[0073] In order to further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they cannot be understood as limiting the protection scope of the present invention.

[0074] Example 1

[0075] Raw material components: Newtonian high-base calcium sulfonate (total base number 400 mgKOH / g, 1.1 kg), 150BS mineral oil (460 mm 2 / s, 1.1 kg), n-butanol (industrial grade, 0.02 kg), dodecylbenzenesulfonic acid (industrial grade, 0.025 kg), water (0.12 kg), 12-hydroxystearic acid (industrial grade, 0.07 kg), nano calcium carbonate particles (50 nm, 0.12 kg) and layered graphite (5000 mesh, 0.025 kg);

[0076] Preparation method: Add 1.1 kg of Newtonian overbased calcium sulfonate, 0.12 kg of nano calcium carbonate particles, 0.07 kg of 12-hydroxystearic acid and 0.44 kg of 150BS mineral oil into the grease reactor in sequence. Start the heat transfer oil circulation to raise the temperature in the reactor to 75 °C and homogenize and mix for 30 min; add 0.02 kg of n-butanol, 0.025 kg of dodecylbenzenesulfonic acid and 0.12 kg of water. After the feeding is completed, raise the temperature of the heat transfer oil to 85 °C in the reactor and carry out saponification reaction for 40 min. The materials in the reactor become significantly thicker; add 0.66 kg of 150BS mineral oil, stir for 30 min, and after mixing evenly, raise the temperature to 100 °C and keep it warm for 120 min for dehydration and de-alcoholization; heat the heat transfer oil to 170 °C in the reactor. When the temperature in the reactor reaches 170 °C, start timing and keep it warm for 10 min for refining; turn on the water cooling system. When the temperature in the reactor drops to 90 °C, add 0.025 kg of layered graphite, keep stirring for 30 min, filter, homogenize and degas to obtain the high-temperature resistant composite grease.

[0077] Example 2

[0078] Raw material components: Newtonian overbased calcium sulfonate (total base number 450 mgKOH / g, 1.2 kg), PAO40 synthetic oil (420 mm 2 / s, 1.0 kg), isopropyl alcohol (industrial grade, 0.025 kg), glacial acetic acid (industrial grade, 0.02 kg), water (0.13 kg), 12-hydroxystearic acid (industrial grade, 0.07 kg), nano calcium carbonate particles (50 nm, 0.075 kg) and layered graphite (3000 mesh, 0.049 kg);

[0079] Preparation method: Add 1.2 kg of Newtonian overbased calcium sulfonate, 0.075 kg of nano calcium carbonate particles, 0.07 kg of 12-hydroxystearic acid, and 0.42 kg of PAO40 synthetic oil into the grease reactor in sequence. Start the heat transfer oil circulation to raise the temperature in the reactor to 78 °C and homogenize and mix for 40 min; add 0.02 kg of isopropanol, 0.025 kg of glacial acetic acid, and 0.12 kg of water. After the feeding is completed, raise the temperature of the heat transfer oil to 83 °C in the reactor and carry out saponification reaction for 50 min. The materials in the reactor become significantly thicker; add 0.58 kg of PAO40 synthetic oil, stir for 40 min. After mixing evenly, raise the temperature to 105 °C and keep warm for 100 min for dehydration and de-alcoholization; heat the heat transfer oil to 165 °C in the reactor. When the temperature in the reactor reaches 165 °C, start timing and keep warm for 12 min for refining; turn on the water cooling system. When the temperature in the reactor drops to 90 °C, add 0.049 kg of layered graphite, keep stirring for 30 min, filter, homogenize, and degas to obtain the high-temperature resistant composite grease.

[0080] Example 3

[0081] Raw material components: Newtonian overbased calcium sulfonate (total base number 430 mgKOH / g, 1.2 kg), PAO40 synthetic oil (420 mm 2 / s, 0.5 kg), trimellitic anhydride ester synthetic ester oil (318 mm 2 / s, 0.5 kg), isopropanol (industrial grade, 0.025 kg), glacial acetic acid (industrial grade, 0.02 kg), water (0.13 kg), 12-hydroxystearic acid (industrial grade, 0.07 kg), nano calcium carbonate particles (50 nm, 0.075 kg), and layered graphite (10,000 mesh, 0.049 kg);

[0082] Preparation method: Add 1.2 kg of Newtonian overbased calcium sulfonate, 0.075 kg of nano calcium carbonate particles, 0.07 kg of 12-hydroxystearic acid, and 0.5 kg of PAO40 synthetic oil into the grease reactor in sequence. Start the heat transfer oil circulation to raise the temperature in the reactor to 78 °C and homogenize and mix for 40 min; add 0.02 kg of isopropanol, 0.025 kg of glacial acetic acid, and 0.12 kg of water. After the feeding is completed, raise the temperature of the heat transfer oil to 83 °C in the reactor and carry out saponification reaction for 50 min. The materials in the reactor become significantly thicker; add 0.5 kg of trimellitic anhydride ester synthetic ester oil, stir for 20 min; after mixing evenly, raise the temperature to 105 °C and keep warm for 90 min for dehydration and de-alcoholization. Heat the heat transfer oil to 165 °C in the reactor. When the temperature in the reactor reaches 165 °C, start timing and keep warm for 15 min for refining; turn on the water cooling system. When the temperature in the reactor drops to 90 °C, add 0.049 kg of layered graphite, keep stirring for 30 min, filter, homogenize, and degas to obtain the high-temperature resistant composite grease.

[0083] Comparative Example 1

[0084] This comparative example is a calcium sulfonate-based grease without nano-calcium carbonate particles and laminated graphite;

[0085] Raw material components: Newtonian overbased calcium sulfonate (total base number 400 mgKOH / g, 1.1 kg), 150BS mineral oil (460 mm 2 / s, 1.1 kg), isopropyl alcohol (industrial grade, 0.02 kg), dodecylbenzenesulfonic acid (industrial grade, 0.025 kg), water (0.12 kg) and 12-hydroxystearic acid (industrial grade, 0.07 kg).

[0086] Preparation method: Add 1.1 kg of Newtonian overbased calcium sulfonate, 0.07 kg of 12-hydroxystearic acid and 0.44 kg of 150BS mineral oil to the grease reactor in sequence, turn on the heat transfer oil circulation, heat the reactor to 75 °C, and homogenize and mix for 30 min; add 0.02 kg of isopropyl alcohol, 0.12 kg of water and 0.025 kg of dodecylbenzenesulfonic acid. After the feeding is completed, heat the heat transfer oil to 85 °C in the reactor and carry out saponification reaction for 40 min. The material in the reactor becomes significantly thicker (by measuring the infrared spectrum of the material, the characteristic absorption peak of calcium carbonate changes from 863 cm -1 to 882 cm -1 , indicating the formation of non-Newtonian overbased calcium sulfonate); add 0.66 kg of 150BS mineral oil, stir for 30 min, after mixing evenly, heat to 100 °C and keep warm for 120 min; heat the heat transfer oil to 170 °C in the reactor. When the temperature in the reactor reaches 170 °C, start timing and keep warm for 10 min; turn on the water cooling system. When the temperature in the reactor drops to 90 °C, filter, homogenize and degas to obtain the calcium sulfonate-based grease.

[0087] Comparative Example 2

[0088] This comparative example is a calcium sulfonate-based grease without laminated graphite;

[0089] Raw material components: Newtonian overbased calcium sulfonate (total base number 400 mgKOH / g, 1.1 kg), 150BS mineral oil (460 mm 2 / s, 1.1 kg), isopropyl alcohol (industrial grade, 0.02 kg), dodecylbenzenesulfonic acid (industrial grade, 0.025 kg), water (0.12 kg), 12-hydroxystearic acid (industrial grade, 0.07 kg) and nano-calcium carbonate particles (0.12 kg);

[0090] Preparation method: Sequentially add 1.1 kg of Newtonian overbased calcium sulfonate, 0.12 kg of nano calcium carbonate particles, 0.07 kg of 12-hydroxystearic acid, and 0.44 kg of 150BS mineral oil into the grease reactor. Start the heat transfer oil circulation to raise the temperature in the reactor to 75 °C, and homogenize and mix for 30 min; add 0.02 kg of isopropanol, 0.12 kg of water, and 0.025 kg of dodecylbenzenesulfonic acid. After the feeding is completed, raise the temperature of the heat transfer oil to 85 °C in the reactor and carry out saponification reaction for 40 min. The material in the reactor becomes significantly thicker (by measuring the infrared spectrum of the material, the characteristic absorption peak of calcium carbonate shifts from 863 cm -1 to 882 cm -1 , indicating the formation of non-Newtonian overbased calcium sulfonate); add 0.66 kg of 150BS mineral oil, stir for 30 min, and after mixing evenly, raise the temperature to 100 °C and keep it warm for 120 min; heat the heat transfer oil to 170 °C in the reactor. When the temperature in the reactor reaches 170 °C, start timing and keep it warm for 10 min; turn on the water cooling system. When the temperature in the reactor drops to 90 °C, filter, homogenize, and degas to obtain calcium sulfonate-based grease without lamellar graphite.

[0091] Comparative Example 3

[0092] This comparative example is calcium sulfonate-based grease without nano calcium carbonate particles.

[0093] Raw material components: Newtonian overbased calcium sulfonate (total base number 400 mgKOH / g, 1.1 kg), 150BS mineral oil (460 mm 2 / s, 1.1 kg), isopropanol (industrial grade, 0.02 kg), dodecylbenzenesulfonic acid (industrial grade, 0.025 kg), water (0.12 kg), 12-hydroxystearic acid (industrial grade, 0.07 kg), and lamellar graphite (0.025 kg);

[0094] Preparation method: Sequentially add 1.1 kg of Newtonian overbased calcium sulfonate, 0.07 kg of 12-hydroxystearic acid, and 0.44 kg of 150BS mineral oil into the grease reactor. Start the heat transfer oil circulation to raise the temperature in the reactor to 75 °C, and homogenize and mix for 30 min; add 0.02 kg of isopropanol, 0.12 kg of water, and 0.025 kg of dodecylbenzenesulfonic acid. After the feeding is completed, raise the temperature of the heat transfer oil to 85 °C in the reactor and carry out saponification reaction for 40 min. The material in the reactor becomes significantly thicker (by measuring the infrared spectrum of the material, the characteristic absorption peak of calcium carbonate shifts from 863 cm -1 to 882 cm -1It is described that non-Newtonian overbased calcium sulfonate is generated); 0.66 kg of 150BS mineral oil is added, and it is stirred for 30 min. After mixing evenly, the temperature is raised to 100 °C and kept warm for 120 min; the heat-conducting oil is heated to 170 °C in the kettle. When the temperature in the kettle reaches 170 °C, timing starts and it is kept warm for 10 min to obtain calcium sulfonate-based grease; the water cooling system is turned on. When the temperature in the kettle drops to 90 °C, 0.025 kg of lamellar graphite is added, and stirring is maintained for 30 min, followed by filtration, homogenization, and degassing to obtain calcium sulfonate-based grease without nano-calcium carbonate particles.

[0095] Comparative Example 4

[0096] Raw material components: overbased calcium sulfonate T106D (1.15 kg), isopropyl alcohol (0.034 kg), water (0.057 kg), nano-calcium carbonate (0.021 kg), glacial acetic acid (0.017 kg), dodecylbenzenesulfonic acid (0.034 kg), 150BS mineral oil (3.55 kg), polyethylene-propylene synthetic oil (3.55 kg), sulfurized olefin 5340 (0.3 kg), high-calcium value calcium sulfonate 75GR (0.15 kg), ethylene-propylene rubber (0.15 kg), and graphite (1 kg);

[0097] Preparation method: Mix 3.55 kg of 150BS mineral oil and 3.55 kg of polyethylene-propylene synthetic oil to obtain base oil; mix 0.034 kg of isopropyl alcohol and part of the water to obtain an isopropyl alcohol aqueous solution, and the mass ratio of isopropyl alcohol to part of the water is 3:7; mix 0.017 kg of glacial acetic acid and the remaining water to obtain a glacial acetic acid aqueous solution, and the mass ratio of glacial acetic acid to the remaining water is 1:3; add part of the base oil and overbased petroleum calcium sulfonate T106D to the saponification kettle, stir and raise the temperature to 70 °C, then the rotation speed is 30 rpm, add the isopropyl alcohol aqueous solution and calcium carbonate, while stirring, raise the temperature to 75 °C, add the glacial acetic acid aqueous solution, after 5 min, raise the temperature to 80 °C, add dodecylbenzenesulfonic acid, raise the temperature to 100 °C, after 30 min, obtain the phase inversion reaction product; raise the temperature of the phase inversion reaction product to 105 °C, increase the stirring speed, the rotation speed is 70 rpm, keep warm for 60 min, continue to raise the temperature to 140 °C, keep warm for 30 min, continue to raise the temperature to 175 °C, and mix with the remaining base oil and 0.15 kg of ethylene-propylene rubber to obtain a mixed material, and the mass ratio of part of the base oil to the remaining base oil is 1:1; raise the temperature of the mixed material to 203 °C, then filter and cool, after cooling to 140 °C, carry out reflux shearing, after 30 min, continue to cool to below 90 °C, add 0.3 kg of sulfurized olefin, 0.15 kg of high-calcium value petroleum calcium sulfonate, and 1 kg of graphite, and stir evenly to obtain composite calcium sulfonate-based grease.

[0098] The systems after the saponification reaction in Examples 1 to 4 were subjected to infrared detection. From the obtained infrared spectra, it was found that the characteristic absorption peaks of calcium carbonate had migrated (in Example 1, from 863 cm -1 to 882 cm -1 , and in Examples 2 and 3, from 863 cm -1 to 883 cm -1 ), indicating that the crystal form of calcium carbonate had changed, forming non-Newtonian overbased calcium sulfonate.

[0099] Figure 1 Figure -1 is the scanning electron microscope image of the 50-nm nano calcium carbonate particles used in the examples. Figure 2 Figure -1 is the scanning electron microscope image of the 5000-mesh layered graphite used in the examples.

[0100] The physical and chemical properties of the greases prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were detected by the following methods, and the results are listed in Table 1: dropping point: GB / T 3498; working penetration and high-temperature penetration: GB / T 269; steel wire mesh oil separation: SH / T0324; evaporation loss: GB / T 7325; oxidation stability pressure drop: SH / T 0325; four-ball tester, PB value and PD value: SH / T0202; wear scar diameter: SH / T 0204.

[0101] Table 1 Physical and chemical properties of the greases prepared in Examples 1 to 3 and Comparative Examples 1 to 3

[0102]

[0103] From the performance results of the physical and chemical indexes of the greases in Examples 1 to 3 in Table 1, it can be seen that the high-temperature resistant and anti-friction composite grease provided by the present invention introduces nano calcium carbonate particles and layered graphite into the calcium sulfonate-based grease, and there is no softening phenomenon of the traditional organic additives containing sulfur or phosphorus elements in the calcium sulfonate-based grease, and it can endow the grease with more excellent high-temperature resistance and anti-wear and anti-friction performance.

[0104] The difference between Example 1 and Comparative Examples 1 to 3 lies in the addition of nano-calcium carbonate particles and layered graphite. Comparative Example 1 does not contain nano-calcium carbonate particles and layered graphite. Comparative Example 2 contains nano-calcium carbonate particles but no layered graphite. Comparative Example 3 does not contain nano-calcium carbonate particles but contains layered graphite. Compared with Comparative Examples 1 to 3, Example 1 has a higher maximum non-seizure load and sintering load, a smaller wear scar diameter, and better tribological properties. This is mainly due to the synergistic effect of nano-calcium carbonate particles and layered graphite in the grease. When the grease enters the surface of the friction pair, at low loads or in the initial stage of friction, the nano-calcium carbonate particles with small particle size and good fluidity can quickly form a lubricating layer. When the load increases or continuous friction occurs, the layered graphite with higher structural strength can form a boundary lubricating layer on the surface of the friction pair, achieving the effect of anti-wear and friction reduction. At the same time, calcium carbonate and layered graphite as solid additives take into account the thermal stability at high temperatures. The change in the high-temperature penetration of Example 1 is smaller, and the indicators of dropping point, steel wire mesh oil separation, and oxidation pressure drop are stable, indicating that Example 1 has excellent high-temperature resistance performance.

[0105] The tribological characteristics of the grease were tested according to the following method:

[0106] The friction coefficient was tested using an Optimol SRV-V type friction and wear testing machine. The specific testing conditions were: testing time of 30 min, testing temperature of 80 °C, testing load of 500 N, testing frequency of 25 Hz, and testing amplitude of 1 mm; the material of the fixed disk ( with a roughness of 25 nm) and the upper ball ( with a roughness of 10 nm) was AISI 52100 steel, and the hardness was 61 - 65 HRC. A MicroXAM three-dimensional non-contact surface mapping instrument was used to obtain the wear volume and three-dimensional photos of the test disk.

[0107] The friction coefficient curves of the greases of Example 1 and Comparative Examples 1 to 3 obtained from the test are as Figure 3 shown; the three-dimensional photos of the test disks after the friction tests of the greases of Example 1 and Comparative Examples 1 to 3 obtained from the test are as Figure 4 shown; the wear volume results obtained from the test are listed in Table 2, and a columnar comparison chart of the wear volumes of Example 1 and Comparative Examples 1 to 3 was drawn according to Table 2, as Figure 5 shown.

[0108] From Figure 3It can be seen that the grease produced in Comparative Example 1 fails to achieve the lubrication effect under high load and high temperature (500 N, 80 °C), and the friction coefficient increases sharply during the running-in stage, resulting in jamming. The grease produced in Comparative Example 2 with only nano-calcium carbonate particles added also shows such a situation, indicating that a single nano-calcium carbonate particle cannot provide sufficient extreme pressure and anti-wear performance under high load. The grease produced in Comparative Example 3 with only laminated graphite added can operate under high load and high temperature (500 N, 80 °C), but there is an obvious problem of increasing friction coefficient during the running-in stage. Combining Figure 4 With the three-dimensional photographs of the test disc after the friction coefficient test completed, it can be seen that the wear marks of Comparative Examples 1 to 3 all exceed the preset amplitude range, indicating that obvious sliding friction has occurred on the friction pair surface. This is because the lubricating oil film fails to be replenished in time, and short-term dry friction occurs on the friction surface.

[0109] Table 2 Wear volume of the test disc after the grease tests of Example 1 and Comparative Examples 1 to 3

[0110] Example <![CDATA[Wear volume (10 -4 mm 3 )]]> Example 1 7.15 Comparative Example 1 17.83 Comparative Example 2 20.58 Comparative Example 3 21.96

[0111] The grease produced in Example 1 with nano-calcium carbonate particles and laminated graphite added can operate normally under high load and high temperature (500 N, 80 °C). During the operation, the friction coefficient curve is stable. Combining Figure 5 With the test disc wear volume data, compared with Comparative Examples 1 to 3, the wear volumes of Example 1 are reduced by 62.26%, 66.08% and 68.65% respectively, indicating that the calcium sulfonate-based grease with nano-calcium carbonate particles and laminated graphite added has excellent anti-friction performance.

[0112] The bearing life is tested according to the following method:

[0113] Add the grease sample into the bearing. When the axial load of the bearing is applied to 111 N, the bearing rotates at a speed of 1000 r / min, the spindle temperature is kept at 160 °C, and the operation cycle is 20 h of operation and 4 h of stop. When the driving motor torque exceeds the set motor interruption value due to grease failure, the test ends, and the results are listed in Table 3; the grease life is expressed in cumulative operating hours. This method represents the lubrication ability of the grease in the rolling bearing by the length of the bearing operation time.

[0114] Table 3 Bearing life of the grease tests of Examples 1 to 3 and Comparative Examples 1 to 4

[0115]

[0116] As can be seen from the bearing life test results in Table 3, the bearing lives of Example 1 and Comparative Example 4 are 80 h and 20 h respectively. The running time of the bearing in Example 1 is 4 times that of Comparative Example 4, indicating that Example 1 can have a better lubrication effect in high-temperature rolling bearings and can extend the normal running time of rolling bearings. This is because the high-mesh layered graphite is more conducive to forming a rigid oil film on the friction pair surface of the rolling bearing. The graphite with larger particles cannot form an attachment on the rolling elements rotating at high speed and is thrown off by the centrifugal force of the rolling elements, unable to achieve the lubrication effect.

[0117] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, not all of them. People can also obtain other embodiments based on this embodiment without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A high temperature resistant composite grease, characterized in that: Includes the following components in percentage by mass: Calcium sulfonate-based grease 85-98.5%; Nano calcium carbonate particles 1-10%; Layered graphite 0.5-5%; The calcium sulfonate-based grease comprises the following raw materials in parts by weight: 21-22 parts of base oil; 21-22 parts of overbased calcium sulfonate; 0.4-0.5 parts of short-chain alcohol; 0.4-0.5 parts of acid conversion agent; 1.4-1.5 parts of dodecyl hydroxystearic acid; 2.4-2.5 parts of water; The average particle size of the nano calcium carbonate particles is 30-80 nm, and the mesh number of the layered graphite is 1200-10000 meshes.

2. The high temperature resistant composite grease according to claim 1, characterized in that: Includes the following components in percentage by mass: Calcium sulfonate-based grease 92-97%; Nano calcium carbonate particles 2-6%; Layered graphite 1-2%.

3. The high temperature resistant composite grease according to claim 1 or 2, characterized in that: The base oil includes one or more of mineral oil, poly-α-olefin oil and ester oil; The total base value of the overbased calcium sulfonate is 400-450 mgKOH / g; The short-chain alcohol includes methanol, isopropanol, n-butanol or amyl alcohol; The acid conversion agent includes a low molecular weight acid or dodecylbenzene sulfonic acid, and the low molecular weight acid includes acetic acid, propionic acid, boric acid or phosphoric acid.

4. The method for preparing the high temperature resistant composite grease according to any one of claims 1 to 3, characterized in that: The following steps are involved: Firstly mixing high base calcium sulfonate, nano calcium carbonate particles, dodecyl hydroxystearic acid and part of base oil to obtain a first mixture; The first mixture, the short-chain alcohol, the acid conversion agent and water are mixed for a second time to undergo a saponification reaction to obtain a second mixture; The second mixture and the remaining base oil are mixed for a third time and then dehydrated and dealcoholized to obtain a third mixture; The third mixture is refined and then mixed with the layered graphite for the fourth time to obtain the high temperature resistant composite grease.

5. The preparation method according to claim 4, characterized in that: The mass percentage of the partial base oil to the total amount of base oil is 40-50%; The temperature of the first mixing is 70-80° C., and the time is 30-60 min.

6. The preparation method according to claim 4, characterized in that: The temperature of the saponification reaction is 80-90° C. and the time is 30-60 minutes.

7. The preparation method according to claim 4, characterized in that: The temperature of the third mixing is 80-90°C; The temperature of the dehydration and dealcoholization is 100-110° C. and the time is 90-120 min.

8. The preparation method according to claim 4, characterized in that: The refining temperature is 160-170° C., and the refining insulation time is 10-15 minutes.

9. The preparation method according to claim 4, characterized in that: The temperature of the fourth mixing is 80-90°C; The fourth mixing method further comprises: filtering, homogenizing and degassing the fourth mixed system in sequence to obtain the high temperature resistant composite grease.

10. Use of the high temperature resistant composite lubricating grease according to any one of claims 1 to 3 or the high temperature resistant composite lubricating grease prepared by the preparation method according to any one of claims 4 to 9 in rolling bearings.

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