Magnesium alloy surface thermal control wear-resistant lubricating film layer and preparation method thereof

Abstract

According to the magnesium alloy surface thermal control wear-resistant lubricating film layer and the preparation method thereof, a quadrangular frustum pyramid structure is machined on the magnesium alloy surface through a laser texturing technology, then a compact ceramic film layer grows on the surface of the quadrangular frustum pyramid structure in situ through a micro-arc oxidation technology, and finally a molybdenum disulfide film is formed on the ceramic film layer through magnetron sputtering. The thermal-control wear-resistant lubricating film layer is obtained. The method can be used for protection treatment of various magnesium alloy parts with thermal control wear-resisting and lubricating performance requirements in a space environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal material surface treatment, and in particular relates to a thermally controlled, wear-resistant lubricating film layer on the surface of a magnesium alloy and a preparation method thereof. Background Art

[0002] Magnesium alloys are a leading choice for new structural materials. Due to their significant advantages, such as high specific strength, high specific stiffness, strong damping and vibration reduction properties, and excellent liquid formability, they are widely used in spacecraft and offer significant lightweighting benefits. However, the relatively soft magnesium alloy matrix and its poor wear resistance limit its application in tribology. Surface treatment is required to strengthen the interface surface and increase its hardness and wear resistance.

[0003] During the manned lunar landing period in the Earth-Moon transfer orbit and the lunar shadow orbit, the heat flux outside the cabin wall of the lunar module, propulsion module and other spacecraft is significantly reduced due to the obstruction of the moon, and the external heat flux is close to zero. The low temperature operating conditions will cause the temperature of the internal structure, equipment and cabin air of the cabin to drop significantly, and there is also a risk of condensation in some areas and equipment surfaces. In addition, when the spacecraft is in an inertial flight attitude towards the sun, the external heat flux will reach a maximum in the local quadrant. This high temperature condition will cause the local surface temperature of the spacecraft to be high, with the temperature difference reaching hundreds of degrees Celsius. The precision instruments inside the spacecraft cannot withstand such a huge temperature difference. To ensure the normal operation of the spacecraft in the orbital flight environment, the thermal control film layer maintains the balance between energy absorption and radiation on the external surface by adjusting the thermal radiation properties of the object surface. Patent CN106757278A discloses an electrolyte for micro-arc oxidation of magnesium alloys for spacecraft and a method for preparing a thermal control film layer on the surface of a magnesium alloy using the electrolyte. The micro-arc oxidation electrolyte contains a main film-forming agent, a colorant, an organic complexing agent and a pH regulator, and has a specific addition order. The hemispherical emissivity of the prepared thermal control film layer is 0.85-0.90, which meets the application requirements of aerospace.

[0004] Lightweighting is a primary requirement for spacecraft. Given limited rocket carrying capacity, lower-density magnesium alloys can be used to increase spacecraft payloads, but their hardness and tribological properties severely restrict their application. Patent CN106119846A discloses a method for preparing a corrosion-resistant and wear-resistant film on the surface of a magnesium alloy. By micro-arc oxidation of the magnesium alloy to produce a 20-50μm ceramic layer, microwave plasma vapor deposition is then used to deposit a dense diamond film. This method effectively prevents corrosion, provides a strong bond, and significantly improves wear resistance. Summary of the Invention

[0005] The purpose of the present invention is to provide a thermal control, wear-resistant and lubricating film layer on the surface of a magnesium alloy and a preparation method thereof. The film layer is an integrated film layer of thermal control, wear resistance and lubrication. The film layer has a strong bonding force with the metal substrate and can enhance the thermal control and wear resistance of the surface of magnesium alloy parts in the lunar environment.

[0006] In order to achieve the above-mentioned purpose, the present invention provides a thermally controlled, wear-resistant lubricating film layer on the surface of a magnesium alloy, comprising: a magnesium alloy substrate, the substrate surface presenting a quadrangular pyramid structure; a ceramic film layer in-situ grown on the quadrangular pyramid structure; and a molybdenum disulfide film grown on the ceramic film layer.

[0007] The above-mentioned thermal control wear-resistant lubricating film layer on the surface of the magnesium alloy, wherein the quadrangular pyramid structure is formed on the surface of the magnesium alloy substrate by laser texturing technology; the ceramic film layer is generated by micro-arc oxidation technology; and the molybdenum disulfide film is generated by magnetron sputtering.

[0008] The above-mentioned thermal control wear-resistant lubricating film layer on the surface of the magnesium alloy has an infrared emissivity of 0.86-0.90, an absorptivity of 0.35-0.40, a hardness of 140HV-150HV, and a friction coefficient of 0.08-0.12.

[0009] Another technical solution provided by the present invention is a method for preparing a thermally controlled, wear-resistant, and lubricating film layer on the surface of a magnesium alloy. Laser texturing technology is used to process a quadrangular pyramid structure on the surface of the magnesium alloy. Micro-arc oxidation technology is then used to in-situ grow a dense ceramic film layer on the surface of the quadrangular pyramid structure. Finally, a layer of molybdenum disulfide film is magnetron sputtered on the ceramic film layer to obtain a thermally controlled, wear-resistant, and lubricating film layer.

[0010] The above-mentioned method for preparing a thermally controlled wear-resistant lubricating film layer on the surface of the magnesium alloy, wherein the laser texturing technology process parameters are: groove spacing of 20μm to 30μm, groove width of 40μm to 50μm, repetition frequency of 950kHz to 1050kHz, laser injection of 2.8J / cm 2 ~3J / cm 2 , the number of repetitions is 25 to 30, the spot size is 25 μm to 35 μm, and the scanning speed is 280 to 300 mm / s.

[0011] The above-mentioned method for preparing a thermally controlled wear-resistant lubricating film layer on the surface of a magnesium alloy, wherein a magnesium alloy part with a surface structure of a quadrangular pyramid is placed in an electrolyte, and a pulsed micro-arc oxidation power supply device is used to perform micro-arc oxidation on the magnesium alloy part. The power supply is set to a forward voltage limit of 530V, a duty cycle of 30% to 35%, a pulse frequency of 450Hz to 500Hz, and a forward current density of 1A / dm 2 ~1.2A / dm 2 , the oxidation temperature is 15℃~25℃, and the oxidation time is 10min~15min.

[0012] The above-mentioned method for preparing a thermally controlled, wear-resistant, lubricating film layer on the surface of a magnesium alloy comprises the following electrolyte formula: Na2SiO3 10g / L to 12g / L, Na3PO4 10g / L to 12g / L, KOH 3g / L to 5g / L, and NaF 1g / L to 1.5g / L.

[0013] The above-mentioned method for preparing a thermally controlled, wear-resistant, lubricating film layer on the surface of a magnesium alloy comprises the following steps: before laser texturing is used to process the tetrahedral structure, the surface of the magnesium alloy is degreased; the degreasing treatment comprises: processing the surface of the magnesium alloy to a roughness of less than 0.5 μm, and wiping and soaking the magnesium alloy with an organic solvent.

[0014] The above-mentioned method for preparing a thermally controlled, wear-resistant, lubricating film layer on the surface of a magnesium alloy further includes water washing and drying steps after growing a dense ceramic film layer and before growing a molybdenum disulfide film. The water washing temperature is room temperature and the water washing time is 10s to 15s. Water-free and oil-free compressed air is used for drying, and the magnesium alloy must not be damaged during drying.

[0015] Compared with the prior art, the beneficial technical effects of the present invention are:

[0016] 1) The thermally controlled, wear-resistant lubricating film prepared by the present invention has low absorptivity, high emissivity, high hardness, and a low friction coefficient, and has strong bonding with the metal substrate, which can meet the thermal control and wear resistance requirements of lunar lander components;

[0017] 2) The thermal control, wear resistance and lubrication integrated film layer grows in situ on the surface of the tetrahedral structure of the substrate. The film layer is uniform and dense, and the thermal control performance of the film layer is anisotropic. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The thermally controlled wear-resistant lubricating film layer on the surface of the magnesium alloy and the preparation method thereof are described in the following examples and drawings.

[0019] Figure 1 Schematic diagram of the surface morphology of the tetrahedral structure after laser texturing.

[0020] Figure 2 Schematic diagram of the cross section of the tetrahedral structure after laser texturing.

[0021] Figure 3 Schematic diagram of the cross section after laser texturing and micro-arc oxidation.

[0022] Figure 4 Schematic diagram of the cross section of the thermally controlled wear-resistant lubricating film layer (laser texturing + micro-arc oxidation + molybdenum disulfide). DETAILED DESCRIPTION

[0023] The following will be combined Figures 1 to 4 The thermally controlled wear-resistant lubricating film layer on the surface of the magnesium alloy and the preparation method thereof are further described in detail.

[0024] The present invention's method for preparing a thermally controlled, wear-resistant, lubricating film on a magnesium alloy surface involves using laser texturing to create a pyramidal structure on the magnesium alloy surface. Micro-arc oxidation is then used to in-situ grow a dense ceramic film on the pyramidal structure. Finally, a molybdenum disulfide film is magnetron sputtered onto the ceramic film to create the thermally controlled, wear-resistant, lubricating film. The thermally controlled, wear-resistant, lubricating film exhibits a high infrared emissivity of 0.86 to 0.90, a low absorptivity of 0.35 to 0.40, a maximum hardness of 140 to 150 HV, and a low friction coefficient of 0.08 to 0.12.

[0025] The method for preparing a thermally controlled, wear-resistant lubricating film layer on the surface of a magnesium alloy specifically comprises:

[0026] Step 1: Degreasing the surface of magnesium alloy parts:

[0027] The magnesium alloy parts are processed to a surface roughness of less than 0.5 μm, and the parts are wiped and soaked with common organic solvents such as acetone and anhydrous ethanol;

[0028] Step 2: Using laser texturing technology to process a quadrangular pyramid structure on the surface of the magnesium alloy part;

[0029] Laser is used to texture the surface of magnesium alloy parts after degreasing to form a quadrangular pyramid structure, such as Figure 1 and Figure 2 ;

[0030] Laser texturing process parameters: groove spacing of 20μm to 30μm, groove width of 40μm to 50μm, repetition frequency of 950kHz to 1050kHz, laser injection of 2.8J / cm 2 ~3J / cm 2 , the number of repetitions is 25-30, the spot size is 25μm-35μm, and the scanning speed is 280-300mm / s;

[0031] Step 3: Use micro-arc oxidation technology to in-situ grow a dense ceramic film layer on the surface of the tetrahedral structure. Figure 3 ;

[0032] A magnesium alloy part with a tetrahedral structure on the surface was placed in an electrolyte and subjected to micro-arc oxidation treatment using a pulsed micro-arc oxidation power supply. The magnesium alloy part served as the anode end and the stainless steel served as the cathode end. The power supply was set with a forward voltage limit of 530 V, a duty cycle of 30% to 35%, a pulse frequency of 450 Hz to 500 Hz, and a forward current density of 1 A / dm 2 ~1.2A / dm 2 , the oxidation temperature is 15℃~25℃, and the oxidation time is 10min~15min;

[0033] Electrolyte formula: Na2SiO3 10g / L~12g / L, Na3PO4 10g / L~12g / L, KOH 3g / L~5g / L, NaF1g / L~1.5g / L;

[0034] Step 4: Water washing: the temperature is room temperature, and the time is 10s to 15s;

[0035] Step 5. Blow dry: Use water-free and oil-free compressed air to blow dry. Be careful not to damage the parts when blowing dry.

[0036] Step 6: magnetron sputter a layer of molybdenum disulfide film on the ceramic film layer to obtain a thermal control wear-resistant lubricating film layer, such as Figure 4 ;

[0037] Magnetron sputtering process parameters: bias voltage is 30V~150V, molybdenum disulfide target current is 1A~10A, titanium target current is 1A~15A, gold target current is 1A~5A, and coating time is 30min~90min.

[0038] The performance of the obtained thermal control wear-resistant lubricating film layer was evaluated using surface morphology test, thermal control performance test, friction performance test and hardness performance test.

[0039] Surface morphology test: Scanning electron microscope (SEM) was used to observe the surface morphology of the micro-arc oxidation film;

[0040] Thermal control performance test: The emissivity was measured using an infrared emissivity meter with a measurement wavelength range of 3μm-35μm, and the result was 0.86-0.90; the absorbance was measured using an ultraviolet-visible-near-infrared spectrophotometer with a measurement wavelength range of 0.25μm-2.5μm, and the result was 0.35-0.40;

[0041] Friction performance test: The test was conducted using a UMT-3 friction and wear tester, with a rotational method, a sliding speed of 100 r / min, a load of 2 N, and a friction pair of Φ8 mm 9Cr18 steel balls.

[0042] Hardness performance test: Use microhardness tester HSV-1000Z to conduct the test in accordance with GB / T 4340.1-2009. Measure three points evenly distributed on the test surface of the sample, record the test results three times, and calculate the average value.

[0043] Example 1:

[0044] The method for preparing the thermally controlled wear-resistant lubricating film layer of this embodiment adopts the following steps:

[0045] Step 1: Processing and degreasing: Process the magnesium alloy parts until the surface roughness is less than 0.5 μm, and use common organic solvents such as acetone and anhydrous ethanol to wipe and soak the parts;

[0046] Step 2: Laser texturing: groove spacing of 20 μm, groove width of 40 μm, repetition frequency of 950 kHz, laser flux of 2.8 J / cm 2 , the number of repetitions is 25, the spot size is 25 μm, and the scanning speed is 280 mm / s;

[0047] Step 3: Thermally controlled micro-arc oxidation of magnesium alloy: Place the magnesium alloy parts after laser texturing in the electrolyte and use pulsed micro-arc oxidation power supply equipment to micro-arc oxidize the magnesium alloy parts. The forward voltage limit is 530V, the duty cycle is 30%, the pulse frequency is 450Hz, and the forward current density is 1.2A / dm 2 , temperature is 15℃~25℃, time is 10min;

[0048] Electrolyte formula: Na2SiO3 12g / L, Na3PO4 12g / L, KOH 5g / L, NaF 1.5g / L;

[0049] Step 4: water washing: room temperature, 10 seconds;

[0050] Step 5. Blow dry: Use water-free and oil-free compressed air to blow dry. Be careful not to damage the parts when blowing dry.

[0051] Step 6: magnetron sputtering of molybdenum disulfide film: bias voltage is 40 V, molybdenum disulfide target current is 5 A, titanium target current is 5 A, gold target current is 2 A, and coating time is 40 min.

[0052] The thermally controlled, wear-resistant lubricating film layer of this embodiment has an off-white appearance, is firmly bonded to the base metal, and does not blister or peel. It has an absorptivity of 0.36, an emissivity of 0.87, a hardness of 145 HV, and a friction coefficient of 0.11.

[0053] Example 2

[0054] The method for preparing the thermally controlled wear-resistant lubricating film layer of this embodiment adopts the following steps:

[0055] Step 1: Processing and degreasing: Process the magnesium alloy parts until the surface roughness is less than 0.5 μm, and use common organic solvents such as acetone and anhydrous ethanol to wipe and soak the parts;

[0056] Step 2: Laser texturing: groove spacing is 30 μm, groove width is 50 μm, repetition frequency is 1050 kHz, laser flux is 3 J / cm 2 , the number of repetitions is 30, the spot size is 35 μm, and the scanning speed is 300 mm / s;

[0057] Step 3: Thermally controlled micro-arc oxidation of magnesium alloy: Place the magnesium alloy parts after laser texturing in the electrolyte and use pulsed micro-arc oxidation power supply equipment to micro-arc oxidize the magnesium alloy parts. The forward voltage limit is 530V, the duty cycle is 35%, the pulse frequency is 500Hz, and the forward current density is 1A / dm 2 , temperature is 15℃~25℃, time is 15min;

[0058] Electrolyte formula: Na2SiO3 10g / L, Na3PO4 10g / L, KOH 3g / L, NaF 1g / L;

[0059] Step 4: Water washing: room temperature, 15 seconds;

[0060] Step 5. Blow dry: Use water-free and oil-free compressed air to blow dry. Be careful not to damage the parts when blowing dry.

[0061] Step 6: magnetron sputtering of molybdenum disulfide film: bias voltage is 120 V, molybdenum disulfide target current is 8 A, titanium target current is 10 A, gold target current is 4 A, and coating time is 80 min.

[0062] The thermally controlled, wear-resistant lubricating film layer of this embodiment has an off-white appearance, is firmly bonded to the base metal, and does not blister or peel. It has an absorptivity of 0.37, an emissivity of 0.88, a hardness of 147 HV, and a friction coefficient of 0.09.

[0063] The above embodiments are merely illustrative of the present invention. Any equivalent variations and improvements based on the technical solutions of the present invention shall not be excluded from the scope of protection of the present invention. The present invention can be used for the protective treatment of various magnesium alloy parts that require thermal control, wear resistance, and lubrication performance in space environments.

Claims

1. A thermally controlled, wear-resistant lubricating film layer on the surface of a magnesium alloy, characterized in that: include: A magnesium alloy substrate, the substrate surface presents a quadrangular pyramid structure; The ceramic film layer is in-situ grown on the tetrahedral structure; Molybdenum disulfide film, grown on the ceramic film layer.

2. The magnesium alloy surface thermal control wear-resistant lubricating film layer according to claim 1, characterized in that: The quadrangular pyramid structure is formed on the surface of a magnesium alloy substrate by laser texturing technology; the ceramic film layer is generated by micro-arc oxidation technology; and the molybdenum disulfide film is generated by magnetron sputtering.

3. The thermal control wear-resistant lubricating film layer on the surface of the magnesium alloy according to claim 1, characterized in that: The thermal control wear-resistant lubricating film layer has an infrared emissivity of 0.86-0.90, an absorptivity of 0.35-0.40, a hardness of 140HV-150HV, and a friction coefficient of 0.08-0.

12.

4. A method for preparing a thermally controlled, wear-resistant lubricating film layer on a magnesium alloy surface, characterized in that: Laser texturing technology is used to process a tetrahedral structure on the surface of the magnesium alloy, and then micro-arc oxidation technology is used to in-situ grow a dense ceramic film layer on the surface of the tetrahedral structure. Finally, a layer of molybdenum disulfide film is magnetron sputtered on the ceramic film layer to obtain a thermally controlled, wear-resistant and lubricating film layer.

5. The method for preparing a thermally controlled, wear-resistant lubricating film layer on a magnesium alloy surface according to claim 4, wherein: The process parameters of laser texturing technology are: groove spacing of 20μm to 30μm, groove width of 40μm to 50μm, repetition frequency of 950kHz to 1050kHz, and laser injection of 2.8J / cm 2 ~3J / cm 2 , the number of repetitions is 25 to 30, the spot size is 25 μm to 35 μm, and the scanning speed is 280 to 300 mm / s.

6. The method for preparing a thermally controlled, wear-resistant lubricating film layer on a magnesium alloy surface according to claim 4, wherein: A magnesium alloy part with a tetrahedral structure on the surface was placed in an electrolyte and subjected to micro-arc oxidation treatment using a pulsed micro-arc oxidation power supply. The power supply was set with a forward voltage limit of 530 V, a duty cycle of 30% to 35%, a pulse frequency of 450 Hz to 500 Hz, and a forward current density of 1 A / dm 2 ~1.2A / dm 2 , the oxidation temperature is 15℃~25℃, and the oxidation time is 10min~15min.

7. The method for preparing a thermally controlled, wear-resistant lubricating film layer on a magnesium alloy surface according to claim 6, wherein: Electrolyte formula: Na2SiO3 10g / L~12g / L, Na3PO4 10g / L~12g / L, KOH 3g / L~5g / L, NaF 1g / L~1.5g / L.

8. The method for preparing a thermally controlled, wear-resistant lubricating film layer on a magnesium alloy surface according to claim 4, wherein: Before laser texturing the tetrahedral structure, the magnesium alloy surface is degreased. The degreasing process includes machining the magnesium alloy surface to a roughness of less than 0.5 μm, and wiping and soaking the magnesium alloy with an organic solvent.

9. The method for preparing a thermally controlled, wear-resistant lubricating film layer on a magnesium alloy surface according to claim 4, wherein: After growing the dense ceramic film layer and before growing the molybdenum disulfide film, the process also includes water washing and drying steps. The water washing temperature is room temperature and the water washing time is 10s to 15s. Water-free and oil-free compressed air is used for drying, and the magnesium alloy must not be damaged during drying.

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