CN115491247A

CN115491247A - High-temperature-resistant solid lubricating coating and preparation and application thereof

Info

Publication number: CN115491247A
Application number: CN202211195310.4A
Authority: CN
Inventors: 徐海燕; 陈磊; 吴彦平; 周惠娣; 李红轩
Original assignee: Lanzhou Institute of Chemical Physics LICP of CAS
Current assignee: Lanzhou Institute of Chemical Physics LICP of CAS
Priority date: 2022-09-29
Filing date: 2022-09-29
Publication date: 2022-12-20
Anticipated expiration: 2042-09-29
Also published as: NL2034183B1; NL2034183A; CN115491247B

Abstract

The invention provides a high-temperature solid lubricating coating, which is prepared by taking phosphate resin as a binder, sulfide, silver powder and rare earth fluoride as lubricants and N, N-dimethylformamide as a diluent according to a certain process, coating the coating on the surface of metal and heating and curing; the phosphate binder is prepared by reacting phosphoric acid, chromium trioxide and aluminum hydroxide in deionized water. The coating disclosed by the invention is good in adhesion to a metal substrate, has excellent tribological performance at high temperature, can solve the problems of lubrication and adhesion of friction parts at ultrahigh temperature of above 800 ℃, is particularly suitable for engine high-temperature alloy self-locking nut fasteners, is good in spraying manufacturability, is easy to control and uniform in coating thickness, passes a normal-temperature locking test and a heat exposure locking test, and effectively solves the problems of lubrication, occlusion and adhesion between contact surfaces of the self-locking nut at high temperature.

Description

High-temperature-resistant solid lubricating coating and preparation and application thereof

Technical Field

The invention belongs to the technical field of surface protection of fasteners, and relates to a solid lubricating coating and a preparation method thereof, which are mainly used for high-temperature alloy lock nut fasteners.

Background

The fastener is the basic spare part of high technical equipment, is common mechanical connection mode, plays key role in the mechanism is connected, and the reliability of fastener determines the life of organism structure. With the application of a large number of new materials and new technologies in the aerospace field and the updating of models, higher requirements are put forward on the fastening and connecting technology of the machine body structure, and the requirements of high-strength fastener products with corrosion resistance, heat resistance, high toughness and fatigue resistance are increased, so that higher requirements are put forward on the surface protection technology of the fastener. The fastener protective coating is required to have excellent corrosion resistance, and must also meet thread screwing performance, high bearing performance, good lubricating wear resistance and high temperature resistance. The fastener of the space rocket engine relates to the problem of lubrication and adhesion at ultrahigh temperature (above 900 ℃), the problems of adhesion, abrasion, occlusion and the like are more easily caused on the threaded surface of the fastener and the contact surface between the fastener and an assembly structure due to the assembly pretightening force of the fastener at the high temperature section, the strength of the fastener is reduced due to abrasion, and the occlusion brings a lot of difficulties for the disassembly and maintenance of the fastener, so that the fastener is not detachable, the maintenance cost is increased, and accidents can be caused in serious cases. In the temperature range, the grease lubricant is ineffective only by adopting solid lubrication, so that the invention of the solid lubricating material with good tribological performance at the temperature of more than 900 ℃ is urgently needed. Surface coating lubrication is one of the major considerations due to its technical features-it can be used on almost all friction components without changing the design and dimensions of the components. For the bonded solid lubricating coating, an organic lubricating coating can be selected at the temperature below 400 ℃ and an inorganic lubricating coating is selected at the temperature of about 500 ℃, while a high-temperature resistant coating which can effectively lubricate the temperature above the temperature is few due to the failure of a common lubricant and the limited selection of a bonding agent at the temperature of about 900 ℃, so that some advanced high-temperature mechanical designs cannot be implemented due to the lack of a high-performance lubricating material as a guarantee.

Foreign SPS company developed an inorganic dry film lubricant coating for a high temperature alloy dodecagonal head bolt, to prevent wear and seizure of a threaded fastener, the use temperature could reach 870 ℃, to replace a silver plating on the fastener (maximum use temperature 650 ℃), and it is likely to be used for a short period of time from the use condition judgment. The domestic product adopts graphite or molybdenum disulfide as lubricant, so the use temperature of the product is not more than 700 ℃; at present, the existing inorganic lubricating coating still cannot meet the requirements on adhesive force, impact resistance and lubricating property at high temperature, so that a high-temperature-resistant solid lubricating coating is designed from two aspects of a high-temperature lubricant and a high-temperature binder, and the coating is an effective means for solving the problems of surface lubrication and adhesion of a fastener at ultrahigh temperature. Meanwhile, the invention of the high-temperature lubricating coating can also be popularized and used on the surfaces of other high-technology equipment parts, such as a rudder bearing and a control device of a space plane, the surface friction seal of a rocket gas turbine blade and a shell, many parts of various engines of space flight and aviation ships and the like, and the lubricating and adhering problem of ultrahigh temperature (above 800 ℃) in the process of launching missile artillery.

Disclosure of Invention

The invention aims to provide a solid lubricating coating and a preparation method thereof, which are mainly used for high-temperature alloy locknut fasteners.

1. High-temperature-resistant solid lubricating coating and preparation

The high-temperature-resistant solid lubricating coating is prepared by taking phosphate resin with high temperature resistance, good stability, toughness and adhesive force as a binder, sulfide, silver powder and rare earth fluoride as lubricants, N, N-dimethylformamide as a diluent according to a certain process, and then coating the coating on the surface of metal by using a spray gun and heating and curing; the phosphate binder is prepared by reacting phosphoric acid, chromium trioxide and aluminum hydroxide in deionized water.

The coating for preparing the coating is prepared from the following components in percentage by weight: 10-13% of phosphate binder (with the solid content of 58-59.5%), 8-11% of sulfide, 16-19% of silver powder, 3-5% of rare earth fluoride and the balance of N, N-dimethylformamide.

The metal sulfide in the lubricant is molybdenum disulfide or tungsten disulfide, is in a powder shape, has the content of more than 98 percent, and has the particle size of less than or equal to 10 mu m. The purity of the silver powder is 99.99%, and the particle size is smaller than 0.5-0.7 mu m. The rare earth fluoride is lanthanum trifluoride or cerium trifluoride, white powder with the content of more than 98 percent and the particle size of less than or equal to 10 mu m. The lubricant system is prepared by compounding sulfide, silver powder and rare earth fluoride in a synergistic manner according to a certain proportion, so that the lubricating problem of the coating at different temperature sections is solved.

The preparation method of the phosphate binder comprises the following steps: mixing chromium trioxide (CrO) ₃ ) Dissolved in deionized water and mixed with phosphoric acid (H) ₃ PO ₄ ) Mixing, heating, adding aluminum hydroxide Al (OH) ₃ Controlling the oil bath reaction temperature to be 100-120 ℃, reacting for 1.5-2.5 h, naturally cooling to obtain phosphate resin, and adjusting the solid content of the phosphate resin to be 58-59.5% by using deionized water for later use; the mass ratio of chromium trioxide to aluminum hydroxide is (1): 0.45 of the total weight of the mixture; the mass ratio of the chromium trioxide to the phosphoric acid is (1): 0.08. the prepared phosphate binder has excellent temperature resistance, and can not be decomposed even at the high temperature of 1800 ℃.

Wherein phosphoric acid (H) ₃ PO ₄ ) And chemical reagent content is greater than or equal to 85%. Al (OH) ₃ White powder, providing Al during the synthesis of phosphate binders ³⁺ The metal ions have better cohesiveness, strength and certain waterproof performance. CrO ₃ White powder, which promotes the formation of an amorphous structure in the adhesive, which, on the one hand, has a three-dimensional continuity and reduces the stresses and strains generated during the phase transition, and, on the other hand, cr ³⁺ Substitution of ions for Al ³⁺ After entering the system, due to the reaction with Al ³⁺ The number of charges of the ions is the same, but the radius is larger than that of Al ³⁺ Ions, therefore Cr ³⁺ The electrostatic field intensity of the ions is small, and the metal ion pair connected with the non-bridge oxygen in the system is adjacent to O ^2- The electrostatic force effect of the system is relatively weakened, the disorder of the system is increased, and the energy of the system is reduced. Both aspects act together to improveStability of the system.

The preparation method of the high-temperature resistant solid lubricating coating comprises the following steps:

(1) Grinding and dispersing solid materials: putting metal sulfide, rare earth fluoride and silver powder which are weighed in proportion into a ball milling tank, adding a proper amount of N, N dimethylformamide to form paste, and carrying out ball milling for 50-60h;

(3) Mixing the material components ground in the step (1) with a phosphate adhesive, and adding a proper amount of N, N-dimethylformamide to the total amount of the required materials;

(4) Dispersing the prepared materials on a high-speed dispersion machine for 10min at a rotating speed of more than or equal to 5000r/min to obtain a solid lubricating coating;

(5) Coating the coating on the surface of the metal by a spray gun, and heating and curing to obtain the required coating; the curing conditions were: curing at 115-125 ℃ for 2h, and then curing at 305-315 ℃ for 1h.

2. Performance and application of high-temperature-resistant solid lubricating coating

The main performance indexes of the high-temperature resistant solid lubricating coating are shown in the table 1.

Note: * A Swiss CSM friction wear testing machine is used for testing 12mm GCr15 steel balls in pairs, the steel balls reciprocate on a coating, the frequency is 10Hz, the amplitude is 2.5mm, and the load is 10N.

The invention relates to a high-temperature resistant solid lubricating coating which has the performances of self-lubrication, wear resistance, adhesion resistance and high temperature resistance, is suitable for the surfaces and interfaces of sliding, rolling and micro-motion contact metal parts, has effective wear resistance and wear reduction, and prevents the metal surfaces from being scratched and adhered. The coating disclosed by the invention is good in adhesion to a metal substrate, is a high-temperature-resistant solid lubricating coating, has excellent lubricating and anti-sticking performances at high temperature, can solve the lubricating and sticking problems of high-temperature friction parts above 800 ℃, is particularly suitable for high-temperature alloy locknut fasteners of engines, is good in spraying manufacturability, is easy to control and uniform in coating thickness, passes through a normal-temperature locking test and a heat exposure locking test, and effectively solves the lubricating, meshing and sticking problems between contact surfaces of locknuts at high temperature, and the like.

Compared with the prior art, the invention has the following advantages:

1. during the preparation of phosphate binder, al is selected simultaneously ³⁺ And Cr ³⁺ Two ions, al ³⁺ The metal ions have better cohesiveness, strength and certain waterproof property, cr ³⁺ Can promote the formation of amorphous structure in the adhesive, on one hand, the amorphous structure has three-dimensional continuity and can reduce stress and strain generated in the phase change process, and on the other hand, cr ³⁺ Substitution of Al by ions ³⁺ After entering the system, due to the reaction with Al ³⁺ The charge number of the ions is the same, but the radius is larger than that of Al ³⁺ Ions, therefore Cr ³⁺ The electrostatic field intensity of the ions is small, and the metal ion pair connected with the non-bridge oxygen in the system is close to O ^2- The action of the electrostatic force is relatively weakened, the disorder of the system is increased, and the energy of the system is reduced. The two aspects work together to improve the stability of the system.

2. According to the invention, the acidic inorganic phosphate is self-prepared and synthesized by a convenient method to serve as the adhesive, and the adhesive has stable chemical properties and stronger adhesive force and toughness than the commercially available phosphate adhesive. The binder produces P upon curing ₂ O ₅ -Al ₂ O ₃ -Cr ₂ O ₃ The compound, although melting at the temperature of 1800 ℃, does not decompose and form eutectic with the combined filler, and is a highly ideal high-temperature resistant solid lubricating coating binder.

3. According to the invention, molybdenum disulfide, rare earth fluoride and silver powder are used as lubricating fillers, and the lubricating performance of the coating at high temperature is improved together by the synergistic compounding of multiple lubricating fillers. The sulfide has excellent lubricating property at low temperature (-50-300 ℃), the silver powder and the rare earth fluoride are used as lubricants at medium temperature (300-800 ℃), the Ag powder used as soft metal has good ductility, and the silver can be sheared along friction surface layers at high temperature, so that the friction coefficient of the coating is reduced, and the wear-resistant effect is achieved. The rare earth fluoride can not only improve the lubricating property of the coating at high temperature, but also inhibit the oxidation of sulfide at high temperature, thereby improving the tribological property of the coating at high temperature.

4. The sulfide reacts with the silver powder at high temperature to generate silver molybdate or silver tungstate, which is a good high-temperature lubricant and can improve the lubricating property of the coating at high temperature (not less than 800 ℃).

5. The coating has the advantages of convenient preparation process, easy control and uniformity of the thickness of the coating, good adhesion of the coating to a metal substrate, excellent lubricating and anti-sticking properties at high temperature, and capability of solving the problems of surface lubrication and adhesion of high-temperature friction parts above 800 ℃.

Detailed Description

The present invention will be described in detail below with reference to specific embodiments.

Example 1

A high-temperature solid lubricating coating is prepared from the following components: 112g of phosphate binder (with the solid content of 58-59.5%), 90g of sulfide (molybdenum disulfide), 165.0g of silver powder, 30.0g of rare earth fluoride (cerium trifluoride), and 593g of N, N-dimethylformamide. Wherein the synthetic phosphate binder comprises the following raw materials in mass: phosphoric acid (H) ₃ PO ₄ ): 620g of chromium trioxide (CrO) ₃ ): 40.5g, aluminum hydroxide Al (OH) ₃ :110.0g and deionized water 229.5g.

The preparation method comprises the following steps:

(1) Synthesis of phosphate resin: dissolving chromium trioxide in water in a three-neck round-bottom flask, mixing with weighed phosphoric acid, placing the round-bottom flask in an oil bath, heating the oil bath to 100 ℃, slowly adding aluminum hydroxide, controlling the temperature of the oil bath to be between 100 and 120 ℃, reacting for 2 hours, naturally cooling to obtain phosphate resin, and adjusting the solid content of the phosphate resin to be 58.0 to 59.5 percent by using deionized water for later use;

(2) Grinding and dispersing solid materials: putting metal sulfide, rare earth fluoride and silver powder which are weighed in proportion into a ball milling tank, and adding a proper amount of N, N dimethylformamide solvent to make the mixture into paste; putting steel balls or ceramic balls with the volume accounting for about one third of the ball milling tank, and performing cumulative ball milling for more than 50 hours;

(3) Mixing the ground material components and the prepared phosphate adhesive in a container, and adding a proper amount of N, N-dimethylformamide to the total amount of the required materials;

(4) Dispersing the prepared materials on a high-speed dispersion machine for 10min at a rotating speed of more than or equal to 5000r/min, and filtering by using a filter screen to obtain a solid lubricating coating;

(5) The coating is coated on the surface of a mechanical part by adopting a process similar to paint spraying, and the required coating is obtained by heating and curing, wherein the curing conditions are as follows: (120. + -. 5). Times.2 h + (310. + -. 5). Times.1 h. The properties are shown in Table 1.

Example 2

A high-temperature solid lubricating coating is prepared from the following components: 114g of phosphate binder (with the solid content of 58-59.5%), 92g of sulfide (tungsten disulfide), 170.0g of silver powder, 32.0g of rare earth fluoride (lanthanum trifluoride) and 582g of N, N-dimethylformamide. Wherein the synthetic phosphate binder comprises the following components in parts by weight: phosphoric acid (H) ₃ PO ₄ ): 625g of chromium trioxide (CrO) ₃ ): 47.5g, aluminum hydroxide Al (OH) ₃ :113.0g and deionized water 214.5g.

The preparation method comprises the following steps:

(1) Synthesis of phosphate resin: dissolving chromium trioxide in water in a three-neck round-bottom flask, mixing with well-weighed phosphoric acid, placing the round-bottom flask in an oil bath, heating the oil bath to 100 ℃, slowly adding aluminum hydroxide, controlling the temperature of the oil bath to be between 100 and 120 ℃, reacting for 2 hours, naturally cooling to obtain phosphate resin, and adjusting the solid content of the phosphate resin to be 58.0 to 59.5 percent by using deionized water for later use;

(5) The coating is coated on the surface of a mechanical part by adopting a process similar to spray painting, and the required coating is obtained by heating and curing, wherein the curing conditions are as follows: (120. + -.5). Times.2 h + (310. + -.5). Times.1 h. The properties are shown in Table 1.

Example 3

A high-temperature solid lubricating coating is prepared from the following components: 115.0g of phosphate binder (with the solid content of 58-59.5%), 95.0g of sulfide (molybdenum disulfide), 175.0g of silver powder, 30.0g of rare earth fluoride (lanthanum trifluoride) and 585g of N, N-dimethylformamide. Wherein the synthetic phosphate binder comprises the following components in parts by weight: phosphoric acid (H) ₃ PO ₄ ): 625.0g of chromium trioxide (CrO) ₃ ): 47.5g, aluminum hydroxide Al (OH) ₃ :113.0g and deionized water 214.5g.

The preparation method is the same as example 1, and the properties are shown in Table 1.

Example 4

A high-temperature solid lubricating coating is prepared from the following components: 120.0g of phosphate binder (with a solid content of 58-59.5%), 100.0g of sulfide, 180.0g of silver powder, 30.0g of rare earth fluoride and 570g of N, N-dimethylformamide. Wherein the synthetic phosphate binder comprises the following components in parts by weight: phosphoric acid (H) ₃ PO ₄ ): 625g of chromium trioxide (CrO) ₃ ): 47.5g, aluminum hydroxide Al (OH) ₃ :113.0g and deionized water 214.5g.

Example 5

High temperature boxThe high-temperature solid lubricating coating for the gold self-locking nut is prepared from the following components in parts by weight: 128.0g of phosphate binder (with the solid content of 58-59.5 percent), 100.0g of sulfide, 180.0g of silver powder, 40.0g of rare earth fluoride and 585g of N, N-dimethylformamide. Wherein the synthetic phosphate binder comprises the following components in parts by weight: phosphoric acid (H) ₃ PO ₄ ): 594.0g, chromium trioxide (CrO) ₃ ): 47.5g, aluminum hydroxide Al (OH) ₃ :113.0g and deionized water 214.5g.

Claims

1. A high temperature resistant solid lubricant coating characterized by: the coating is prepared by taking phosphate resin as a binder, sulfide, silver powder and rare earth fluoride as lubricants and N, N-dimethylformamide as a diluent according to a certain process, and then heating and curing the coating after coating the coating on the surface of metal; the phosphate binder is prepared by reacting phosphoric acid, chromium trioxide and aluminum hydroxide in deionized water.

2. The high temperature resistant solid lubricant coating of claim 1, wherein: the coating for preparing the coating comprises the following components in percentage by weight: 10 to 13 percent of phosphate binder, 8 to 11 percent of sulfide, 16 to 19 percent of silver powder, 3 to 5 percent of rare earth fluoride and the balance of N, N-dimethylformamide.

3. The high temperature-resistant solid lubricating coating of claim 1 or 2, characterized in that: the sulfide is molybdenum disulfide or tungsten disulfide.

4. The high temperature resistant solid lubricant coating of claim 1, wherein: the preparation method of the phosphate binder comprises the following steps: dissolving chromium trioxide in deionized water, mixing with phosphoric acid, heating, adding aluminum hydroxide, controlling the oil bath reaction temperature at 100-120 ℃, reacting for 1.5-2.5 h, naturally cooling to obtain phosphate resin, and adjusting the solid content of the phosphate resin to 58-59.5% by using deionized water for later use; the mass ratio of chromium trioxide to aluminum hydroxide is (1): 0.45 of; the mass ratio of the chromium trioxide to the phosphoric acid is 1:0.08.

5. the preparation method of the high-temperature-resistant solid lubricating coating as claimed in any one of claims 1 to 4, which comprises the following steps:

(3) Mixing the ground material components in the step (1) with a phosphate adhesive, and adding a proper amount of N, N-dimethylformamide to the total amount of the required materials;

(4) Dispersing the prepared materials on a high-speed dispersion machine to obtain a solid lubricating coating;

6. The high temperature resistant solid lubricant coating of claim 5, wherein: the dispersion on the high-speed dispersion machine is carried out for 10min at the rotating speed of more than or equal to 5000 r/min.

7. Use of the high temperature resistant solid lubricant coating of claim 1 in a superalloy self-locking nut.