CN110747461A

CN110747461A - Wear-resistant coating with molybdenum disulfide, polytetrafluoroethylene and solid lubricant injected into friction surface and micropore array

Info

Publication number: CN110747461A
Application number: CN201911035614.2A
Authority: CN
Inventors: 魏仕勇; 张友亮; 付青峰; 金莹; 谌昀; 万珍珍
Original assignee: Institute of Applied Physics of Jiangxi Academy of Sciences
Current assignee: Institute of Applied Physics of Jiangxi Academy of Sciences
Priority date: 2019-10-29
Filing date: 2019-10-29
Publication date: 2020-02-04

Abstract

The invention discloses a method for preparing a special blind hole array template on a laser coating wear-resistant iron-based alloy coating by adopting an optical fiber laser drilling technology, and a solid lubricant is carried and stored in a micropore reservoir. Specifically, molybdenum disulfide and polytetrafluoroethylene powder with different concentrations are mixed to prepare micropore array templates with different densities. The deposited molybdenum disulfide and polytetrafluoroethylene powder are densified by adopting a microwave sintering method, the lowest friction coefficient of a 20% micropore density template assembled by MoS2-10wt% of polytetrafluoroethylene powder is preferably selected, and a u-shaped micropore array template most suitable for wear-resistant Electrophoretic Deposition (EDP) is prepared.

Description

Wear-resistant coating with molybdenum disulfide, polytetrafluoroethylene and solid lubricant injected into friction surface and micropore array

Technical Field

The invention relates to a method for embedding a self-lubricating agent into a wear-resistant coating on the surface of a metal material, and also relates to a packaging mode of a self-lubricating agent in the wear-resistant coating.

Background

Molybdenum disulfide (MoS2) has strong covalent intralayer and weak van der waals interlayer interactions and is widely recognized as an effective solid lubricant. Many studies based on the function of MoS2 were mainly to prepare MoS2 thin films or coatings by RF PVD, thermal spraying, and laser cladding. However, MoS2 lubricant films prepared by PVD or thermal spray methods are prone to failure under high surface loads due to low adhesion to the substrate. In order to reduce the friction coefficient and prolong the service life of the alloy, the invention provides an application duplex technology of a solid lubricant on a deformed surface based on a laser co-deformation technology. The pattern of grooves or dimples created on the surface of the alloy can act as a reservoir for lubricant, as the lubricant can be stored in organized cavities and then released during the friction process, effectively reducing the coefficient of friction of the alloy. However, loose lubricant is dispersed in the texture region and is difficult to retain in the grooves, resulting in uneven surfaces and deteriorated wear performance. Therefore, maintenance of the lubricant in the deformation zone is particularly important to extend the useful life of the lubricant.

Polytetrafluoroethylene (PTFE) is a thermoplastic polymer with a melting point of 600k, maintains high strength, toughness and self-flowability at low temperatures as low as 5k, and maintains good flexibility at temperatures above 194 k. The coefficient of friction of PTFE against polished steel is typically 0.05-0.10, the third lowest of the known solid materials. However, PTFE exhibits poor wear and abrasion resistance, leading to early failure and seal leakage problems. The invention adopts proper filling materials to obviously improve the wear resistance of PTFE. Therefore, the complementation of MoS2 and PTFE in the present invention shows good frictional wear properties.

Drawings

FIG. 1 microstructure of laser deposited Fe-Cr-Ni-C coating.

FIG. 2 laser different focusing distances produce micro-hole shapes (a) -2mm (b) 0mm (c) 1mm (d) 2 mm.

Figure 3 topography of EPD coating (a) top view (b) cross sectional view.

Fig. 4 morphology of the sintered sample (1) no sintering (2) 300 ℃ (3) 350 ℃ (4) 400 ℃ (5) 500 ℃.

Figure 5 sintered morphology of EPD coating on cladding coating (1) no sintering (2) 300 ℃ (3) 350 ℃ (4) 400 ℃ (5) 500 ℃.

Figure 6 XRD samples of EPD coatings at different sintering temperatures.

FIG. 7 the effect of sintering temperature on the coefficient of friction.

FIG. 8 MoS2-10wt% PTFE micropore area scanning electron microscopy topography (a) unsintered (b) sintered at 300 ℃ for 2 hours.

FIG. 9 the effect of PTFE content on the coefficient of friction.

FIG. 10 Effect of PTFE content on wear surface morphology (a) 0% (b) 5% (c) 10% (d) 15% (e) 20%.

FIG. 11 Effect of micropore density on coefficient of friction.

FIG. 12 impact of micropore density on wear surface (a) 10% (b) 20% (c) 30% (d) 40%.

Detailed Description

By laser cladding on medium carbon steel (0.45C), a wear-resistant coating with Fe-0.1C-15.0Cr-0.5Ni (wt%) composition and microhardness HV 0.1650 was obtained. The laser power is 1.8 kW, the scanning speed is 15 mm.s 1, the beam diameter is 5mm, the coating thickness is 1.5 mm, and the overlapping rate is 50%. The cross-section of the coating structure is shown in fig. 1. The surface roughness of the laser clad samples was ground to 1500 mesh, ultrasonically cleaned, and then dried in an oven prior to laser drilling.

And (3) adopting an LMC2011 type IPG fiber laser with the wavelength of 1064 nm to research the blind hole array on the surface of the laser coating. And (3) carrying out a laser drilling experiment in the atmosphere by changing the defocusing distance of the laser beam, and optimizing the section of the micropore. And the optimized laser parameters are used for preparing the blind hole array template for subsequent electrophoretic deposition.

Molybdenum disulfide powder (about 1 μm) and polytetrafluoroethylene powder (about 0.5 μm, molecular weight 10) in various ratios⁴-10⁵) C is shown in Table 1 as a solid content of 10 g/L₁₆H₂₆O₂The surface of the solution was activated and then dispersed by distilled water to a solid content of 5 g/L. The suspension was stirred in a magnetic stirring apparatus for 1 hour and then dispersed in an ultrasonic apparatus for 1 hour. The anode adopts two parallel stainless steel plates with a distance of 15mm, and the cathode adopts a laser cladding coating. Electrophoretic deposition (EPD) the microporous template was deposited at 60v for 20 minutes.

The deposited template was microwave sintered using a microwave sintering apparatus (Changshafei Thermom) with a frequency of 2.45 GHz and a power of 1.4 kW to densify the deposited lubricant. The deposited microporous template is embedded by adopting a mixture of silicon carbide and alumina powder and is quickly and uniformly heated. In high-purity argon (99.99 percent), microwave sintering is carried out at four different temperatures of 300 ℃, 350 ℃, 400 ℃ and 500 ℃, and the heating rate is 3 ℃/min. And measuring the accurate temperature of the sample by using an infrared thermometer, and controlling by changing the microwave power. And heating the deposited microporous template to the sintering temperatures, preserving the heat for 120min, and finally cooling the sintered sample to room temperature in the air.

Abrasion resistance test the frictional behavior of the sintered specimens at room temperature was investigated using an MM-U10G ring block abrasion tester. The deposited and sintered composite template ring was slid over a laser covered block of Fe-0.1C-15.0Cr-0.5Ni coating (size 30 mm. times.30 mm. times.12 mm). The sliding test was carried out in air, applying a load of 100N, at a speed of 50rpm, for a test time of 180 min. The coefficient of friction is continuously recorded by a computer connected to the tester sensor. All ring surfaces were ground and polished to remove the lubricating oil deposited outside the micropores, and then cleaned with acetone before the sliding test.

Claims

A novel wear-resistant coating of a micro-pore array on a friction surface injected by MoS 2-polytetrafluoroethylene solid lubricant and an assembly method thereof, the process is that the coating composed of Fe-0.1C-15.0Cr-0.5Ni (wt%) is obtained by laser cladding on the metal surface, the surface of the laser cladding matrix sample is polished to more than 1500 meshes and is cleaned by ultrasonic, then drying in an oven, drilling the blind hole array on the surface of the laser coating by using an IPG fiber laser, defocusing the distance by preferably using a laser beam, performing laser drilling in the atmosphere, preparing a blind hole array template for subsequent electrophoretic deposition (EPD) filling lubricant based on the optimized laser parameters, electrophoretically depositing MoS 2-polytetrafluoroethylene solid lubricant into micropores, finally, microwave sintering is carried out, so that the deposited lubricant is more densified, and the wear-resistant and self-lubricating effect of the coating is achieved.
2. The MoS 2-PTFE solid lubricant according to claim 1, wherein both MoS2 and PTFE are powders, the molybdenum disulfide powder has an average particle size of 1 μm, the dispersion rate in the suspension during electrophoretic deposition is 10-12.5g/L, the polytetrafluoroethylene powder has an average particle size of 0.5 μm, the dispersion rate in the suspension is 0-2.5g/L, the surface activation is performed by using a C16H26O2 solution with a solid content of 10 g/L, the solution is dispersed by distilled water to a total solid content of 5g/L, the suspension is stirred in a magnetic stirring device for 1 hour, and then dispersed in an ultrasonic device for 1 hour.
3. Fe-0.1C-15.0Cr-0.5Ni (wt%) composition coating according to claim 1, characterized in that the processing method is laser cladding with microhardness HV_0.1650, laser power 1.8 kW, scanning speed 15mm s < -1 >, beam diameter 5mm, plating thickness 1.5 mm, and overlapping rate 50%.
4. The laser drilling according to claim 1, characterized in that the laser coating surface is drilled with an array of blind holes using an IPG fiber laser with a wavelength of 1064 nm on the coating described in claim 3, and the template is immersed in an acidic solution (HF/HNO 3=1:3) for about 25 seconds after drilling to remove spatter around the laser drilling.
5. The electrophoretic deposition (EPD) process according to claim 1, wherein two parallel stainless steel plates with a distance of 15mm are used as anode, laser clad coating is used as cathode, electrophoretic deposition voltage is 60V, and deposition time is 20 MIN.
6. The microwave sintering process according to claim 1, characterized in that the microwave sintering environment is rapidly and uniformly heated in high-purity argon (99.99%), the heating rate is controlled to be about 3 ℃/min, the heating temperature is 500 ℃, the temperature is kept for 120min, and finally, the sintered sample is cooled to the room temperature in the air.