CN112647074A - High-hardness wear-resistant self-lubricating coating and preparation method thereof - Google Patents
High-hardness wear-resistant self-lubricating coating and preparation method thereof Download PDFInfo
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- 238000000576 coating method Methods 0.000 title claims abstract description 82
- 239000011248 coating agent Substances 0.000 title claims abstract description 79
- 238000002360 preparation method Methods 0.000 title claims abstract description 13
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 105
- 239000000956 alloy Substances 0.000 claims abstract description 105
- 238000004372 laser cladding Methods 0.000 claims abstract description 80
- 239000000843 powder Substances 0.000 claims abstract description 76
- 229910001105 martensitic stainless steel Inorganic materials 0.000 claims abstract description 63
- 238000000034 method Methods 0.000 claims abstract description 41
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims abstract description 29
- 229910052709 silver Inorganic materials 0.000 claims abstract description 28
- 239000004332 silver Substances 0.000 claims abstract description 28
- 229910000623 nickel–chromium alloy Inorganic materials 0.000 claims abstract description 22
- UFGZSIPAQKLCGR-UHFFFAOYSA-N chromium carbide Chemical compound [Cr]#C[Cr]C#[Cr] UFGZSIPAQKLCGR-UHFFFAOYSA-N 0.000 claims abstract description 19
- 229910003470 tongbaite Inorganic materials 0.000 claims abstract description 19
- 238000010438 heat treatment Methods 0.000 claims abstract description 18
- ITRNXVSDJBHYNJ-UHFFFAOYSA-N tungsten disulfide Chemical compound S=[W]=S ITRNXVSDJBHYNJ-UHFFFAOYSA-N 0.000 claims abstract description 18
- 230000032683 aging Effects 0.000 claims abstract description 14
- 238000001816 cooling Methods 0.000 claims abstract description 11
- 238000001035 drying Methods 0.000 claims abstract description 10
- 238000002156 mixing Methods 0.000 claims abstract description 8
- 230000001681 protective effect Effects 0.000 claims abstract description 7
- 239000012535 impurity Substances 0.000 claims abstract description 6
- 230000008569 process Effects 0.000 claims description 19
- 239000002994 raw material Substances 0.000 claims description 15
- 239000002245 particle Substances 0.000 claims description 14
- 238000005253 cladding Methods 0.000 claims description 12
- 230000005855 radiation Effects 0.000 claims description 7
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 238000004140 cleaning Methods 0.000 claims description 3
- 230000003746 surface roughness Effects 0.000 claims description 2
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- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 239000000758 substrate Substances 0.000 description 7
- 238000010790 dilution Methods 0.000 description 5
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- 238000012360 testing method Methods 0.000 description 5
- 238000005336 cracking Methods 0.000 description 4
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- 238000012986 modification Methods 0.000 description 4
- 230000007547 defect Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
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- CWQXQMHSOZUFJS-UHFFFAOYSA-N molybdenum disulfide Chemical compound S=[Mo]=S CWQXQMHSOZUFJS-UHFFFAOYSA-N 0.000 description 3
- 229910052982 molybdenum disulfide Inorganic materials 0.000 description 3
- 229910052759 nickel Inorganic materials 0.000 description 3
- 238000004321 preservation Methods 0.000 description 3
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- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 229910018487 Ni—Cr Inorganic materials 0.000 description 1
- 244000137852 Petrea volubilis Species 0.000 description 1
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- VNNRSPGTAMTISX-UHFFFAOYSA-N chromium nickel Chemical compound [Cr].[Ni] VNNRSPGTAMTISX-UHFFFAOYSA-N 0.000 description 1
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- 230000008018 melting Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
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Classifications
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C24/00—Coating starting from inorganic powder
- C23C24/08—Coating starting from inorganic powder by application of heat or pressure and heat
- C23C24/10—Coating starting from inorganic powder by application of heat or pressure and heat with intermediate formation of a liquid phase in the layer
- C23C24/103—Coating with metallic material, i.e. metals or metal alloys, optionally comprising hard particles, e.g. oxides, carbides or nitrides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
- B22F1/105—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material containing inorganic lubricating or binding agents, e.g. metal salts
Abstract
The invention relates to a high-hardness wear-resistant self-lubricating coating and a preparation method thereof, oxide skin and impurities are removed from the surface of a martensitic stainless steel alloy, and the martensitic stainless steel alloy is cleaned for later use; mixing 70-85% of nickel-chromium alloy, 5-20% of chromium carbide, 2-5% of tungsten disulfide and 3-5% of silver according to a ratio to prepare alloy powder, drying the alloy powder, placing the alloy powder in laser cladding equipment, then placing the martensitic stainless steel alloy for preheating, introducing protective gas for laser cladding after the alloy powder is preheated to a set temperature, preparing a laser cladding layer on the surface of the martensitic stainless steel alloy, and cooling the laser cladding layer to room temperature; and carrying out aging heat treatment on the martensitic stainless steel alloy with the laser cladding layer on the surface, and finally preparing the high-hardness wear-resistant self-lubricating coating on the surface of the martensitic stainless steel alloy. The coating prepared by the method has extremely low friction coefficient and higher surface hardness.
Description
Technical Field
The invention relates to the technical field of material surface modification, in particular to a high-hardness wear-resistant self-lubricating coating and a preparation method thereof.
Background
15-5PH or 17-4PH belongs to martensite precipitation hardening stainless steel, and the main application fields of the martensite precipitation hardening stainless steel are corrosion environments, grooves, fasteners, equipment and equipment for manufacturing high-pressure valves and the like of aerospace, airplane parts and components. Although various properties can be obtained through heat treatment conditions, the alloy still has inherent defects of low hardness, high and unstable friction coefficient, poor wear resistance, serious adhesive wear and fretting wear sensitivity and the like, and the application of the alloy as a friction wear kinematic pair part and the exertion of the potential of excellent mechanical properties of the alloy are limited.
The development of the current laser cladding treatment technology is increasingly paid attention to, for example, the surface modification of the laser cladding material can improve the surface hardness, wear resistance or corrosion resistance of a component, improve the surface machining performance, repair parts which fail due to abrasion and prolong the service life of the components; therefore, the method for preparing the coating by the laser cladding surface modification technology to improve the tribological behavior of the material is an extremely effective means, and the laser cladding technology has good development prospect in the field of surface treatment.
In the prior art, although the wear rate of the coating is greatly reduced by mainly adding molybdenum disulfide as a lubricant, the wear rate of the coating is still high, so that the wear rate of friction matching parts which are in contact wear with the coating is improved by 2-4 times, the wear rate of the whole structure is poor, and the coating needs to bear high-load impact and scouring in the working process, so that the requirements on the bonding strength and the impact toughness of the coating and a substrate are higher. In addition, the surface treatment technology by laser cladding has been widely applied to base materials such as titanium alloy, nickel-based alloy and the like, and the laser cladding of the nickel-based coating on the martensite precipitation hardening stainless steel is still difficult. This is due to the high crack sensitivity of nickel based coatings, the source of thermal cracks in the coating cracking along coarse hard phase grain boundaries and possibly even cracking of the structure near the heat affected zone of the substrate. Therefore, the laser cladding coating is adopted to improve the abrasion performance of the martensite precipitation hardening stainless steel, and relevant reports and applications are few.
Disclosure of Invention
In order to solve the technical problems of poor self-lubricating property and high friction coefficient of the coating in the prior art, the high-hardness wear-resistant self-lubricating coating and the preparation method thereof are provided. The coating of the method is prepared by adding a chromium carbide cermet wear-resistant phase, first lubricating phase tungsten disulfide and second lubricating phase silver powder into a nickel-chromium alloy master phase and preparing the coating with extremely low friction coefficient through a laser cladding process.
In order to achieve the purpose, the invention is realized by the following technical scheme:
the high-hardness wear-resistant self-lubricating coating comprises the following raw materials in percentage by mass: 70-85% of nickel-chromium alloy, 5-20% of chromium carbide, 2-5% of tungsten disulfide and 3-5% of silver.
Furthermore, the powder particle sizes of the raw materials are all 30-200 mu m. Particle sizes too fine to 30 μm are easily ablated by laser, and too coarse to be more than 200 μm are more difficult to melt and will further form coarse particle defects, so this particle size range is the optimum powder particle size for laser cladding.
The invention provides a preparation method of the high-hardness wear-resistant self-lubricating coating, which comprises the following steps:
(1) removing oxide skins and impurities from the surface of the martensitic stainless steel alloy, and cleaning for later use;
(2) mixing nickel-chromium alloy, chromium carbide, tungsten disulfide and silver according to a ratio to prepare alloy powder, drying the alloy powder, placing the dried alloy powder in laser cladding equipment, then placing the martensitic stainless steel alloy for preheating, introducing protective gas for laser cladding after the alloy powder is preheated to a set temperature, preparing a laser cladding layer on the surface of the martensitic stainless steel alloy, and cooling the laser cladding layer to room temperature;
(3) and carrying out aging heat treatment on the martensitic stainless steel alloy with the laser cladding layer on the surface, and finally preparing the high-hardness wear-resistant self-lubricating coating on the surface of the martensitic stainless steel alloy.
Further, the method of removing the oxide scale and impurities is to polish the surface with a sand paper or a polishing machine until the surface roughness is less than 0.8.
Further, the drying time of the alloy powder is 8-10 h.
Further, the powder feeding amount of the laser cladding equipment for the alloy powder is set to be 10 g/min-60 g/min.
Further, the preheating speed is 10-100 ℃/min, and the preheating temperature is 200-480 ℃.
Further, the protective gas is Ar or N2，N2The flow rate is 8L/h-20L/h, and the Ar flow rate is 10L/h-25L/h.
Further, the laser cladding process parameters are as follows: and performing radiation scanning cladding on the area to be coated on the surface of the martensitic stainless steel alloy by using a circular light spot laser beam, and simultaneously directly feeding the alloy powder into the laser beam, wherein the laser power is set to be 0.6 KW-2 KW, the diameter of a light spot is set to be 3 mm-5 mm, the powder feeding diameter is set to be 1.5 mm-6 mm, and the scanning speed is set to be 2 mm/s-15 mm/s. The laser cladding layer with compact and uniform structure and excellent performance is formed by strictly controlling the energy and the powder feeding amount of the laser beam and adjusting the dilution effect of the laser cladding layer on the martensitic stainless steel alloy base material, and then the residual stress is eliminated by low-temperature aging heat treatment to obtain a stable and uniform coating structure, so that the obtained coating has the characteristics of high hardness, wear resistance and self lubrication.
Further, the temperature of the aging heat treatment is 150-550 ℃, and the heat preservation time is 1-5 h.
The beneficial technical effects are as follows: the method is to carry out surface modification on the surface of the martensitic stainless steel alloy, obtain a laser cladding layer by carrying out laser cladding on the surface of the martensitic stainless steel alloy, and then carry out aging heat treatment to obtain the high-hardness wear-resistant self-lubricating coating. The coating of the invention is that chromium carbide is added in a nickel-chromium alloy mother phase as a metal ceramic wear-resistant phase, tungsten disulfide and silver are added as lubricating phases, meanwhile, silver is used as a reinforcing phase and is uniformly dissolved and distributed in an adhesive phase taking nickel-chromium alloy as a mother phase through a laser cladding process, the silver as the reinforcing phase and the lubricating phase can effectively improve the surface hardness of the coating taking the nickel-chromium alloy as the mother phase and the wear resistance with the matrix material, reduce the generation of microcracks, the cracking tendency of the coating can be effectively reduced, because the Ag improves the capability of supporting a hard phase of the nickel-chromium alloy through strengthening a gamma-Ni matrix phase by solid solution, and the Ag reduces the height-width ratio of carbide, reduces the brittleness of the carbide and increases the toughness of the coating, and in addition, fine molybdenum disulfide particles generated in situ are not easy to fall off in the friction process, so that the grinding effect of abrasive particles on a matrix material is better resisted; through the coating components and the process improvement, a synergistic effect is formed, the friction coefficient of the coating is greatly reduced, the wear resistance and the service life of the coating are improved, and meanwhile, the application range of the coating on precipitation hardening stainless steel and other base materials is expanded, so that the coating prepared by the method has lower friction coefficient and good and stable self-lubricating property compared with the traditional solid lubricant particles, and meanwhile, the surface hardness is higher, and the energy consumption and the production cost are effectively reduced.
Drawings
FIG. 1 is a metallographic structure diagram of a laser cladding layer obtained by the step (2) in example 5 at a magnification of 500.
Fig. 2 is a surface topography of the high-hardness wear-resistant self-lubricating coating prepared in example 5 after grinding, and fig. 2 is a macro-scale diagram enlarged by 10 times.
FIG. 3 shows the results of the friction coefficient test of the high-hardness self-lubricating wear-resistant coating prepared in example 5 on the right, and the results of the friction coefficient test of the 15-5PH martensitic stainless steel alloy as the base material on the left.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention and the accompanying drawings, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Unless specifically stated otherwise, the numerical values set forth in these examples do not limit the scope of the invention. Techniques, methods known to those of ordinary skill in the relevant art may not be discussed in detail, but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.
The experimental methods of the following examples, which are not specified under specific conditions, are generally determined according to national standards; if no corresponding national standard exists, the method is carried out according to the universal international standard or the standard requirement proposed by related enterprises. Unless otherwise indicated, all parts are parts by weight and all percentages are percentages by weight.
Example 1
The high-hardness wear-resistant self-lubricating coating comprises the following raw materials in percentage by mass: 70% of nickel-chromium alloy, 20% of chromium carbide, 5% of tungsten disulfide and 5% of silver; wherein the powder particle sizes of the raw materials are all less than or equal to 150 μm.
The preparation method of the high-hardness wear-resistant self-lubricating coating comprises the following steps:
(1) polishing the surface of the martensitic stainless steel alloy with the pH of 15-5 by using abrasive paper until Ra is less than 0.8 so as to remove oxide scale and surface impurities, blowing by using compressed air, and cleaning the surface of the polished martensitic stainless steel alloy base material by using absolute ethyl alcohol for later use;
(2) mixing the nickel-chromium alloy, the chromium carbide, the tungsten disulfide and the silver according to the proportion to prepare alloy powder, drying for 8-10 h, placing the alloy powder in a powder feeder of laser cladding equipment, setting the powder feeding amount to be 20g/min, then placing the martensitic stainless steel alloy on a heating platform of the laser cladding equipment for preheating, setting the preheating speed to be 95 ℃/min, preheating to 480 ℃, and then performing laser cladding: the method comprises the following steps of carrying out radiation scanning cladding on a region to be coated on the surface of a martensitic stainless steel alloy substrate by adopting a circular light spot laser beam, enabling a powder feeding channel to move synchronously with a laser head, directly feeding alloy powder into the laser beam, introducing Ar as protective gas during the process, controlling the environment atmosphere at the Ar flow rate of 20L/h, and carrying out laser cladding by adopting a laser cladding process as follows: the laser power is 0.6KW, the diameter of a light spot is 3mm, the powder feeding diameter is 5mm, the scanning speed is 6mm/s, the dilution effect of laser cladding alloy powder on a martensitic stainless steel alloy base material is adjusted by strictly controlling the energy and the powder feeding amount of a laser beam, a laser cladding layer is prepared on the surface of the martensitic stainless steel alloy, and the martensitic stainless steel alloy is transferred to a cooling platform of laser cladding equipment to be cooled to room temperature by air;
(3) and (3) carrying out aging heat treatment on the martensitic stainless steel alloy with the laser cladding layer on the surface at 200 ℃, preserving heat for 5 hours, and finally preparing the high-hardness wear-resistant self-lubricating coating on the surface of the martensitic stainless steel alloy.
Example 2
The high-hardness wear-resistant self-lubricating coating comprises the following raw materials in percentage by mass: 85% of nickel-chromium alloy, 10% of chromium carbide, 2% of tungsten disulfide and 3% of silver; wherein the powder particle sizes of the raw materials are all less than or equal to 150 μm.
The preparation method of the high-hardness wear-resistant self-lubricating coating comprises the following steps:
(1) polishing the surface of the 17-4PH martensitic stainless steel alloy by a polishing machine (120-;
(2) mixing the nickel-chromium alloy, the chromium carbide, the tungsten disulfide and the silver according to the proportion to prepare alloy powder, drying for 8-10 h, placing the alloy powder in a powder feeder of laser cladding equipment, setting the powder feeding amount to be 25g/min, then placing the martensitic stainless steel alloy on a heating platform of the laser cladding equipment for preheating, setting the preheating speed to be 75 ℃/min, preheating to 300 ℃, and then performing laser cladding: performing radiation scanning cladding on the region to be coated on the surface of the martensitic stainless steel alloy substrate by adopting a circular light spot laser beam, synchronously moving a powder feeding channel along with a laser head, directly feeding alloy powder into the laser beam, and introducing N during the process2As a shielding gas, N2Controlling the environment atmosphere at the flow rate of 15L/h, wherein the laser cladding process comprises the following steps: laser power of 0.8KW, spot diameter of 5mm, powder feeding straightThe diameter is 2mm, the scanning speed is 8mm/s, the dilution effect of laser cladding alloy powder on a martensitic stainless steel alloy base material is adjusted by strictly controlling the energy and the powder feeding amount of a laser beam, a laser cladding layer is prepared on the surface of the martensitic stainless steel alloy, and the martensitic stainless steel alloy base material is transferred to a cooling platform of laser cladding equipment to be cooled to room temperature by air;
(3) and (3) carrying out aging heat treatment on the martensitic stainless steel alloy with the laser cladding layer on the surface at 550 ℃, preserving heat for 1h, and finally preparing the high-hardness wear-resistant self-lubricating coating on the surface of the martensitic stainless steel alloy.
Example 3
The high-hardness wear-resistant self-lubricating coating comprises the following raw materials in percentage by mass: 80% of nickel-chromium alloy, 13% of chromium carbide, 3% of tungsten disulfide and 4% of silver; wherein the powder particle sizes of the raw materials are all less than or equal to 150 μm.
The preparation method of the high-hardness wear-resistant self-lubricating coating comprises the following steps:
(1) polishing the surface of the 15-5PH martensitic stainless steel alloy by a polishing machine (120-;
(2) mixing the nickel-chromium alloy, the chromium carbide, the tungsten disulfide and the silver according to the proportion to prepare alloy powder, drying for 8-10 h, placing the alloy powder in a powder feeder of laser cladding equipment, setting the powder feeding amount to be 35g/min, then placing the martensitic stainless steel alloy on a heating platform of the laser cladding equipment for preheating, setting the preheating speed to be 50 ℃/min, preheating to 400 ℃, and then performing laser cladding: performing radiation scanning cladding on the region to be coated on the surface of the martensitic stainless steel alloy substrate by adopting a circular light spot laser beam, synchronously moving a powder feeding channel along with a laser head, directly feeding alloy powder into the laser beam, and introducing N during the process2As a shielding gas, N2Controlling the environment atmosphere at the flow rate of 10L/h, wherein the laser cladding process comprises the following steps: the laser power is 1.2KW, the spot diameter is 4mm, the powder feeding diameter is 4mm, the scanning speed is 6mm/s, and the laser power and the powder feeding amount are strictly controlled to adjust the laserDiluting the martensitic stainless steel alloy base material by the clad alloy powder, preparing a laser cladding layer on the surface of the martensitic stainless steel alloy, transferring the laser cladding layer to a cooling platform of laser cladding equipment, and air-cooling to room temperature;
(3) and (3) carrying out aging heat treatment on the martensitic stainless steel alloy with the laser cladding layer on the surface at 350 ℃, preserving heat for 3 hours, and finally preparing the high-hardness wear-resistant self-lubricating coating on the surface of the martensitic stainless steel alloy.
Example 4
The high-hardness wear-resistant self-lubricating coating comprises the following raw materials in percentage by mass: 75% of nichrome, 17.5% of chromium carbide, 4% of tungsten disulfide and 4.5% of silver; wherein the powder particle sizes of the raw materials are all less than or equal to 150 μm.
The preparation method of the high-hardness wear-resistant self-lubricating coating comprises the following steps:
(1) polishing the surface of the 15-5PH martensitic stainless steel alloy by a polishing machine (120-;
(2) mixing the nickel-chromium alloy, the chromium carbide, the tungsten disulfide and the silver according to the proportion to prepare alloy powder, drying for 8-10 h, placing the alloy powder in a powder feeder of laser cladding equipment, setting the powder feeding amount to be 35g/min, then placing the martensitic stainless steel alloy on a heating platform of the laser cladding equipment for preheating, setting the preheating speed to be 35 ℃/min, preheating to 350 ℃, and then performing laser cladding: the method comprises the following steps of carrying out radiation scanning cladding on a region to be coated on the surface of a martensitic stainless steel alloy substrate by adopting a circular light spot laser beam, enabling a powder feeding channel to move synchronously with a laser head, directly feeding alloy powder into the laser beam, introducing Ar as protective gas during the process, controlling the environment atmosphere at the Ar flow rate of 15L/h, and carrying out laser cladding by adopting a laser cladding process as follows: the laser power is 1.0KW, the diameter of a light spot is 4mm, the powder feeding diameter is 3mm, the scanning speed is 4.5mm/s, the dilution effect of laser cladding alloy powder on a martensitic stainless steel alloy base material is adjusted by strictly controlling the energy and the powder feeding amount of a laser beam, a laser cladding layer is prepared on the surface of the martensitic stainless steel alloy, and the martensitic stainless steel alloy is transferred to a cooling platform of laser cladding equipment to be cooled in air to room temperature;
(3) and (3) carrying out aging heat treatment on the martensitic stainless steel alloy with the laser cladding layer on the surface at 200 ℃, preserving heat for 4 hours, and finally preparing the high-hardness wear-resistant self-lubricating coating on the surface of the martensitic stainless steel alloy.
Example 5
The high-hardness wear-resistant self-lubricating coating comprises the following raw materials in percentage by mass: 78% of nickel-chromium alloy, 14% of chromium carbide, 3.7% of tungsten disulfide and 4.3% of silver; wherein the powder particle sizes of the raw materials are all less than or equal to 150 μm.
The preparation method of the high-hardness wear-resistant self-lubricating coating comprises the following steps:
(1) polishing the surface of the 15-5PH martensitic stainless steel alloy by a polishing machine (120-;
(2) mixing the nickel-chromium alloy, the chromium carbide, the tungsten disulfide and the silver according to the proportion to prepare alloy powder, drying for 8-10 h, placing the alloy powder in a powder feeder of laser cladding equipment, setting the powder feeding amount to be 15g/min, then placing the martensitic stainless steel alloy on a heating platform of the laser cladding equipment for preheating, setting the preheating speed to be 60 ℃/min, preheating to 400 ℃, and then performing laser cladding: the method comprises the following steps of carrying out radiation scanning cladding on a region to be coated on the surface of a martensitic stainless steel alloy substrate by adopting a circular light spot laser beam, enabling a powder feeding channel to move synchronously with a laser head, directly feeding alloy powder into the laser beam, introducing Ar as protective gas during the process, controlling the environment atmosphere at the Ar flow rate of 15L/h, and carrying out laser cladding by adopting a laser cladding process as follows: the laser power is 1.6KW, the diameter of a light spot is 4mm, the powder feeding diameter is 4.5mm, the scanning speed is 15mm/s, the dilution effect of laser cladding alloy powder on a martensitic stainless steel alloy base material is adjusted by strictly controlling the energy and the powder feeding amount of a laser beam, a laser cladding layer is prepared on the surface of the martensitic stainless steel alloy, and the martensitic stainless steel alloy is transferred to a cooling platform of laser cladding equipment to be cooled in air to room temperature;
(3) and (3) carrying out aging heat treatment on the martensitic stainless steel alloy with the laser cladding layer on the surface at 380 ℃, preserving heat for 3 hours, and finally preparing the high-hardness wear-resistant self-lubricating coating on the surface of the martensitic stainless steel alloy.
The metallographic structure diagram of the laser cladding layer prepared by the step (2) is shown in fig. 1, and it can be seen from fig. 1 that in the 500-fold metallographic structure picture of the coating, the light-colored part is a nickel-chromium alloy mother phase and is dissolved in the mother phase along with a low-melting point silver element (silver is dissolved in the mother phase due to the low melting point), the larger particle point is that a chromium carbide hard phase is dispersed and distributed in the nickel-chromium mother phase, and the smaller point-like structure is that the molten and dispersed molybdenum disulfide is dispersed and distributed in the coating.
The surface appearance of the high-hardness wear-resistant self-lubricating coating of the embodiment after grinding is shown in fig. 2, and as can be seen from fig. 2, the coating is clad on the martensitic stainless steel alloy base material in a metallurgical bonding manner without an obvious interface, and the surface and the cross section of the coating have no structural defects such as cracks, air holes and the like, which shows that the coating prepared by the method of the invention has uniform and compact structure, and the stress between the coating and the base material is effectively controlled in the cladding process.
Comparative example 1
The comparative example is the same as the method of example 5, except that silver is not added into the coating, and the mass percentages of the raw materials are as follows: 78% of nickel-chromium alloy, 14% of chromium carbide and 8% of tungsten disulfide.
The coatings prepared in the above examples and comparative examples were subjected to a friction coefficient test and a coating hardness test, and the data are shown in table 1.
TABLE 1 coating Properties obtained in examples and comparative examples
(Note: + indicates less microcracks and, + + indicates more microcracks.)
As can be seen from Table 1, the friction coefficient of the 15-5PH base material is 0.55-0.6, the friction coefficient of the original base material can be reduced to 0.2-0.25 from 0.55-0.6 after the coating is prepared on the surface of the base material by the method, the friction coefficient is reduced by about 3 times, the prepared coating has no tissue defects such as micro-cracks, air holes and the like, the wear rate between the coating and a friction pair is effectively slowed down by greatly reducing the friction coefficient, and the test result of the friction coefficient of the coating in example 5 is shown in FIG. 3. In addition, the hardness of the coating prepared by the method of example 5 is improved to more than HRC55 from HRC38 of the base material, and the hardness and the wear resistance of the working surface are greatly improved.
Compared with the coating added with the silver element in the comparative example 1, the hardness of the coating added with the silver element in the example 5 is not greatly different from that of the comparative example 1, but the friction coefficient of the coating added with the silver element in the example 5 is reduced by at least 16%; the coating of example 5 with the added silver element has no obvious microcracks, while the coating of comparative example 1 without the added silver element has more microcracks, which shows that the added silver element has a certain contribution to the reduction of the microcracks. The reason is that on one hand, Ag improves the capability of supporting a hard phase of the nickel-chromium alloy through solid solution strengthening of a gamma-Ni matrix phase, and on the other hand, Ag reduces the aspect ratio of carbide, reduces the brittleness of the carbide, increases the toughness of a coating, reduces microcracks and reduces the cracking tendency of the coating.
The generation of microcracks is dependent on the coating composition on the one hand and on the process parameters on the other hand. The reason why less microcracks were generated in examples 2 and 3 is mainly due to: on one hand, the addition of the silver element can enable the coating structure to be more uniform, and the generation of microcracks is reduced to a certain extent, but on the other hand, a large number of microcracks can be generated due to the fact that the preheating temperature is too low, the cladding speed is high, the cladding amount is large, the final cooling speed is high, and the heat preservation temperature is low in the heat preservation stage of low-temperature aging. Therefore, the generation of microcracks needs to be controlled by reasonably controlling technological parameters such as preheating temperature, cladding speed, cladding amount, cooling speed, low-temperature aging temperature and the like in the laser cladding process.
Compared with similar coatings prepared by other processes, the high-hardness wear-resistant self-lubricating coating prepared by the method has more stable repeatability and lower cost, can completely meet the service working condition of actual parts through the requirement of dye penetrant inspection, and greatly improves the performance and service life of workpieces which are not subjected to laser cladding treatment.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.
Claims (10)
1. The high-hardness wear-resistant self-lubricating coating is characterized by comprising the following raw materials in percentage by mass: 70-85% of nickel-chromium alloy, 5-20% of chromium carbide, 2-5% of tungsten disulfide and 3-5% of silver.
2. The high-hardness, wear-resistant, self-lubricating coating according to claim 1, wherein the raw materials each have a powder particle size of 30 to 200 μm.
3. The process for preparing a high-hardness, wear-resistant, self-lubricating coating according to claim 1 or 2, characterized in that it comprises the following steps:
(1) removing oxide skins and impurities from the surface of the martensitic stainless steel alloy, and cleaning for later use;
(2) mixing nickel-chromium alloy, chromium carbide, tungsten disulfide and silver according to a ratio to prepare alloy powder, drying the alloy powder, placing the dried alloy powder in laser cladding equipment, then placing the martensitic stainless steel alloy for preheating, introducing protective gas for laser cladding after the alloy powder is preheated to a set temperature, preparing a laser cladding layer on the surface of the martensitic stainless steel alloy, and cooling the laser cladding layer to room temperature;
(3) and carrying out aging heat treatment on the martensitic stainless steel alloy with the laser cladding layer on the surface, and finally preparing the high-hardness wear-resistant self-lubricating coating on the surface of the martensitic stainless steel alloy.
4. The method of claim 3, wherein the oxide scale and impurities are removed by sanding with a sandpaper or a grinder until the surface roughness is less than 0.8.
5. The production method according to claim 3, wherein the drying time of the alloy powder is 8 to 10 hours.
6. The production method according to claim 3, wherein a powder feeding amount of the laser cladding apparatus for the alloy powder is set to 10g/min to 60 g/min.
7. The method according to claim 3, wherein the preheating speed is 10 ℃/min to 100 ℃/min, and the preheating temperature is 200 ℃ to 480 ℃.
8. The method according to claim 3, wherein the shielding gas is Ar or N2，N2The flow rate is 8L/h-20L/h, and the Ar flow rate is 10L/h-25L/h.
9. The preparation method according to claim 3, wherein the laser cladding process parameters are as follows: and performing radiation scanning cladding on the area to be coated on the surface of the martensitic stainless steel alloy by using a circular light spot laser beam, and simultaneously directly feeding the alloy powder into the laser beam, wherein the laser power is set to be 0.6 KW-2 KW, the diameter of a light spot is set to be 3 mm-5 mm, the powder feeding diameter is set to be 1.5 mm-6 mm, and the scanning speed is set to be 2 mm/s-15 mm/s.
10. The preparation method according to claim 3, wherein the temperature of the aging heat treatment is 150-550 ℃ and the holding time is 1-5 h.
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Application publication date: 20210413 |