METHOD FOR PROTECTION AGAINST FRETTING FATIGUE BY COMPOUND MODIFICATION VIA LASER SHOCK PEENING AND COATING LUBRICATION

Abstract

The present disclosure provides a method for protection against fretting fatigue by compound modification via laser shock peening and coating lubrication, where a group of micro-pits distributed into a regular array is firstly formed in a surface of a metal material by using laser shock peening, with a single micro-pit having a diameter of 1 to 10 mm and a depth of 1 to 20 μm; and the micro-pits are then coated with a lubricant by coating preparation. Based on the micro-pit styling feature and surface residual compressive stress introducing feature of the laser shock peening, with compound modification by surface texturing via the laser shock peening and coating lubrication, the surface of the material can be reinforced by residual compressive stress, coating lubrication and surface micro-pit texturing with a synergistic effect, thus allowing for improved fretting fatigue behavior of the material.

Claims

1. A method for protection against fretting fatigue by compound modification via laser shock peening and coating lubrication, comprising forming a group of micro-pits distributed into a regular array on a surface of a metal material by using laser shock peening, with a single micro-pit having a diameter of 1 to 10 mm and a depth of 1 to 20 μm; and coating the micro-pits with a lubricant by coating preparation.

2. The method for protection against fretting fatigue by compound modification via laser shock peening and coating lubrication according to claim 1, wherein the laser shock peening is carried out by partial overlapping of individual spots along a laser shock path, wherein the spot is circular or square and an overlapping rate of the spots is 10% to 50%.

3. The method for protection against fretting fatigue by compound modification via laser shock peening and coating lubrication according to claim 2, specifically comprising the following steps: S1: surface pretreatment of a specimen to be treated by laser shock peening; covering a surface of the specimen to be treated by laser shock peening with an aluminum foil and spraying deionized water over a position for laser shock peening to form a 1 mm thick deionized water film; S2: formation of a group of micro-pits in the surface of the specimen to be treated by laser shock peening by using the laser shock peening; S3: surface cleaning of the laser shock peened specimen; removing the aluminum foil from the surface of the specimen after the completion of the laser shock peening and cleaning the surface of the laser shock peened specimen with an organic solvent; S4: surface coating of the specimen with the lubricant; coating the surface of micro-pits (micro-pit texture) with the lubricant by coating technology, wherein during the coating preparation, temperatures of the specimen and the lubricant and an ambient temperature do not exceed 600° C.

4. The method for protection against fretting fatigue by compound modification via laser shock peening and coating lubrication according to claim 3, wherein the laser shock peening is carried out by using a pulsed solid-state neodymium glass laser with a laser light wavelength of 1064 nm, a pulse width of 10 to 30 ns, a pulse energy density of 1 to 30 J, and a circular or square spot having a diameter of 1 to 10 mm.

5. The method for protection against fretting fatigue by compound modification via laser shock peening and coating lubrication according to claim 1, wherein the coating preparation is carried out by plasma spraying, physical deposition, chemical deposition or electroplating.

6. The method for protection against fretting fatigue by compound modification via laser shock peening and coating lubrication according to claim 1, wherein the lubricant is a solid coating material.

7. The method for protection against fretting fatigue by compound modification via laser shock peening and coating lubrication according to claim 6, wherein the lubricant is a CuNiIn material, molybdenum disulfide, a soft metal or nylon.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] To describe the technical solutions in examples of the present disclosure or in the prior art more clearly, the accompanying drawings required for describing the examples or the prior art will be described below briefly. Apparently, the accompanying drawings in the following description show some examples of the present disclosure, and other drawings can be derived from these accompanying drawings by a person of ordinary skill in the art without creative efforts.

[0024] FIG. 1 is a schematic diagram of a laser shock peening textured surface with micro-pits according to an example of the present disclosure.

[0025] FIG. 2 is a schematic diagram of a cross section after compound modification via laser shock peening and coating lubrication according to an example of the present disclosure.

[0026] In the figures, 1 denotes a specimen for laser shock peening, while 2 a spot and laser shock path representation during the laser shock peening, 3 a cross sectional view of the laser shock peened specimen in the thickness direction, and 4 a contour line of micro-pits formed in the surface of the laser shock peened specimen, and 5 a coating material.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] In order to make the objectives, technical solutions and advantages of the examples of the present disclosure clearer, the technical solutions in the examples of the present disclosure will be described below clearly and completely with reference to the accompanying drawings in the examples of the present disclosure. Apparently, the described examples are some rather than all of the examples of the present disclosure. The following description of at least one exemplary example is merely illustrative, and not intended to limit the present disclosure and application or use thereof in any way. All other examples derived from the examples of the present disclosure by a person of ordinary skill in the art without creative efforts shall fall within the protection scope of the present disclosure.

Example 1

[0028] As shown in FIG. 1 and FIG. 2, the present disclosure provides a method for protection against fretting fatigue by compound modification via laser shock peening and coating lubrication. The laser shock peening and the coating lubrication were combined to provide a novel integrated surface protection technique, which specifically included the following steps.

[0029] The surface of micro-pits (micro-pit texture) distributed into a regular array was firstly formed in a surface of a metal material by using laser shock peening, with a single micro-pit having a diameter of 1 to 10 mm and a depth of 1 to 20 μm; and the micro-pits were then coated with a lubricant by coating preparation.

[0030] Further, the laser shock peening was carried out by partial overlapping of individual spots along a laser shock path, where the spot was circular or square and an overlapping rate of the spots was 10% to 50%. In the present disclosure, the coverage of the laser shock peening on the surface of the specimen could be above 100%.

[0031] Further, the coating preparation was carried out by plasma spraying, physical deposition, chemical deposition or electroplating.

[0032] Further, the lubricant was a solid coating material.

[0033] Further, the lubricant was a CuNiIn material, molybdenum disulfide, a soft metal or nylon.

[0034] FIG. 1 shows a specimen 1 for laser shock peening, a spot and laser shock path representation 2 during the laser shock peening, a cross sectional view 3 of the laser shock peened specimen in the thickness direction, a contour line 4 of micro-pits formed in the surface of the laser shock peened specimen and a coating material 5.

[0035] Further, the method for protection against fretting fatigue by compound modification via laser shock peening and coating lubrication specifically included the following steps:

[0036] S1: surface pretreatment of the specimen 1 to be treated by laser shock peening.

[0037] A surface of the specimen 1 to be treated by laser shock peening was covered with a 0.12 mm thick aluminum foil, so that the material surface was protected, and deionized water was sprayed over a position for laser shock peening to form a 1 mm thick deionized water film for inhibiting plasma over-expansion and increasing shock wave pressure.

[0038] S2: formation of a group of micro-pits (micro-pit texture) in the surface of the specimen to be treated by laser shock peening by using the laser shock peening.

[0039] The surface of the specimen 1 to be treated by laser shock peening was shocked with circular or square spots along a laser shock path as shown in FIG. 1. The surface of the specimen was reinforced by partial overlapping of individual spots, guaranteeing that the coverage of the laser shock peening on the specimen surface was above 100%. An overlapping rate of the spots was 10% to 50% and the spot had a diameter (side length) of 1 to 10 mm. A group of micro-pits (micro-pit texture) distributed into a regular array was formed in the surface along the set laser shock path, with the contour line 4 of the micro-pits formed in surface of the laser shock peened specimen being as shown in FIG. 1.

[0040] The process parameters of the laser shock peening were as follows: a pulsed solid-state neodymium glass (ND:YAG) laser with a laser light wavelength of 1064 nm, a pulse width of 10 to 30 ns, a pulse energy density of 1 to 30 J, and a circular or square spot having a diameter (side length) of 1 to 10 mm.

[0041] S3: surface cleaning of the laser shock peened specimen.

[0042] The aluminum foil was removed from the surface of the specimen after the completion of the laser shock peening and the surface of the laser shock peened specimen 1 was cleaned with an organic solvent.

[0043] S4: surface coating of the specimen with the lubricant.

[0044] The surface of micro-pits (micro-pit texture) was coated with the lubricant by coating technology, so that compound modification by micro-pit texturing via the laser shock peening and the coating lubrication was achieved. During the coating preparation, temperatures of the specimen and the lubricant and an ambient temperature did not exceed 600° C.

[0045] Based on the micro-pit styling feature and surface residual compressive stress introducing feature of the laser shock peening, with compound modification by surface texturing via the laser shock peening and coating lubrication, the surface of the material can be reinforced by residual compressive stress, coating lubrication and surface micro-pit texturing with a synergistic effect, thus allowing for improved fretting fatigue behavior of the material. The compound modification can result in enhanced fretting wear resistance of the coating, reduced surface friction, retarded residual stress relaxation, and prolonged fretting fatigue life.

[0046] Finally, it should be noted that the above example is merely intended to describe the technical solutions of the present disclosure, rather than to limit the present disclosure. Although the present disclosure is described in detail with reference to the above example, a person of ordinary skill in the art will understand that modifications can be made to the technical solutions described in the above example or equivalent replacements can be made to some or all technical features thereof. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to depart from the scope of the technical solutions of the example of the present disclosure.