阅读说明：本技术 一种镁合金表面等离子喷涂Al/Al2O3涂层的制备方法 (Plasma spraying Al/Al on magnesium alloy surface2O3Method for producing a coating ) 是由 王文权 任东亭 张新戈 王铎 樊慧璋 任晓雪 徐临超 于 2021-07-12 设计创作，主要内容包括：本发明提供了一种镁合金表面等离子喷涂Al/Al-(2)O-(3)涂层的制备方法,它包括如下步骤：(1)对镁合金基体表面进行喷砂处理；(2)在喷砂处理的镁合金基体表面加工滑槽型织构：采用精密机床在喷砂后的镁合金基体表面均匀加工出多条相互平行且上窄下宽的梯形滑槽；(3)制备Al涂层；(4)制备Al/Al-(2)O-(3)涂层。该制备方法通过精密加工制得的梯形滑槽型织构,减小了激光加工带来的热变形,且易于控制梯形滑槽的结构参数,相比其他结构有效增大了涂层与镁合金基体的互锁效应,解决了现有技术中涂层与基体结合力弱的技术问题。(The invention provides a magnesium alloy surface plasma spraying Al/Al 2 O 3 The preparation method of the coating comprises the following steps: (1) carrying out sand blasting treatment on the surface of the magnesium alloy substrate; (2) processing a chute type texture on the surface of the magnesium alloy substrate subjected to sand blasting: uniformly processing a plurality of parallel trapezoidal sliding grooves with narrow tops and wide bottoms on the surface of the magnesium alloy substrate subjected to sand blasting by using a precision machine tool; (3) preparing an Al coating; (4) preparation of Al/Al 2 O 3 And (4) coating. The trapezoidal sliding groove type texture prepared by precision machining in the preparation method reduces the stressThermal deformation brought by photo-processing is easy to control the structural parameters of the trapezoidal sliding groove, compared with other structures, the interlocking effect of the coating and the magnesium alloy substrate is effectively increased, and the technical problem that the bonding force of the coating and the substrate is weak in the prior art is solved.)

1. Plasma spraying Al/Al on magnesium alloy surface₂O₃The preparation method of the coating is characterized by comprising the following steps: it comprises the following steps:

(1) carrying out sand blasting treatment on the surface of the magnesium alloy substrate: removing oxide skin and impurities on the surface of the magnesium alloy substrate, and then removing scraps on the surface of the magnesium alloy substrate by using a blower or ultrasonic cleaning;

(2) processing a chute type texture on the surface of the magnesium alloy substrate subjected to sand blasting: uniformly processing a plurality of trapezoidal sliding grooves which are parallel to each other and narrow at the top and wide at the bottom on the surface of the magnesium alloy substrate subjected to sand blasting by using a precision machine tool, and cleaning the surface of the magnesium alloy substrate and residual scraps in the trapezoidal sliding grooves to increase the bonding area between the surface of the magnesium alloy substrate and a coating;

(3) preparing an Al coating: placing the magnesium alloy substrate treated in the step (2) in a heat-preserving table for preheating, wherein the temperature of the heat-preserving table is far lower than the melting temperature of the magnesium alloy substrate, and then plasma-spraying an Al coating on the surface of the magnesium alloy substrate, wherein the Al coating is a bonding layer;

(4) preparation of Al/Al₂O₃Coating: the magnesium alloy substrate which finishes the Al coating spraying in the step (3) is still placed in a heat preservation table for heat preservation, and the Al coating is subjected to heat preservationSurface plasma spraying of Al/Al₂O₃Coating of said Al/Al₂O₃The coating is a working layer and Al/Al₂O₃The coating finishes spraying within three hours after the trapezoidal chute is processed.

2. The magnesium alloy surface plasma sprayed Al/Al according to claim 1₂O₃The preparation method of the coating is characterized by comprising the following steps: in the step (2), the distance between the lower bottoms of any two adjacent trapezoidal sliding grooves is 150 μm, the length of the upper bottom of each trapezoidal sliding groove is 38-42 μm, the height of each trapezoidal sliding groove is h, h is more than 0 and less than 30 μm, the lower bottom angle of each trapezoidal sliding groove is alpha, and alpha is more than 75 degrees and less than 90 degrees.

3. The magnesium alloy surface plasma sprayed Al/Al according to claim 2₂O₃The preparation method of the coating is characterized by comprising the following steps: and (3) spraying Al powder with the particle size of 78-82 microns when spraying the Al coating, placing the magnesium alloy substrate in a heat-insulating table for preheating when spraying, wherein the temperature of the heat-insulating table is 350 ℃, the spraying angle is an included angle of 135 degrees formed by the axis of a nozzle and the extension direction of the trapezoidal sliding chute, and discharging gas in the trapezoidal sliding chute by using airflow sprayed by the nozzle.

4. The magnesium alloy surface plasma sprayed Al/Al according to claim 3₂O₃The preparation method of the coating is characterized by comprising the following steps: spraying Al/Al in the step (4)₂O₃Al/Al is adopted for coating₂O₃And spraying the mixed powder, wherein the temperature of a heat preservation table is 350 ℃, the spraying voltage is 50V, the spraying current is 700A, the spraying distance is 90mm, argon is used as protective gas and powder feeding gas, the airflow pressure of the argon is 0.48MPa, the powder feeding amount is 30g/min, and the spraying angle is that a nozzle is vertical to the surface of the magnesium alloy matrix.

5. The magnesium alloy surface plasma sprayed Al/Al according to claim 4₂O₃The preparation method of the coating is characterized by comprising the following steps: the Al/Al₂O₃Mass of mixed powderThe amount ratio is: 40 mass percent of Al powder and 60 mass percent of Al₂O₃Powder, the grain diameter of the Al powder is 80 mu m, and the Al powder₂O₃The particle size of the powder was 50 μm.

6. The magnesium alloy surface plasma sprayed Al/Al according to claim 5₂O₃The preparation method of the coating is characterized by comprising the following steps: the thickness of the Al coating in the step (3) is 95-105 μm, and the Al/Al coating in the step (4)₂O₃The thickness of the coating was 195-205 μm.

7. The magnesium alloy surface plasma sprayed Al/Al according to claim 6₂O₃The preparation method of the coating is characterized by comprising the following steps: the thickness of the Al coating in the step (3) is 100 mu m, and the Al/Al coating in the step (4)₂O₃The thickness of the coating was 200. mu.m.

8. The magnesium alloy surface plasma sprayed Al/Al according to claim 7₂O₃The preparation method of the coating is characterized by comprising the following steps: and (3) spraying Al powder with the particle size of 80 microns when spraying the Al coating in the step (3).

9. The magnesium alloy surface plasma sprayed Al/Al according to claim 8₂O₃The preparation method of the coating is characterized by comprising the following steps: the magnesium alloy substrate is an AZ61 magnesium alloy plate with the thickness of 50mm multiplied by 6mm, and the thickness of the magnesium alloy substrate is 6 mm.

10. The magnesium alloy surface plasma sprayed Al/Al according to claim 9₂O₃The preparation method of the coating is characterized by comprising the following steps: and (2) adopting 16# brown corundum sand when carrying out sand blasting treatment in the step (1), wherein the sand blasting distance is 50-70mm, the sand blasting angle is 60-80 degrees, the sand feeding is kept uniform, the sand blasting nozzle swings twice at a constant speed, and the moving speed is reduced when the sand is blasted to the edge of the magnesium alloy matrix.

Technical Field

The invention relates to a magnesium alloy surface plasma spraying Al/Al₂O₃A preparation method of a coating belongs to the technical field of processing of thermal spraying coatings.

Background

Magnesium is one of the most abundant light metal elements on the earth, has low density, high specific strength and specific stiffness, good biocompatibility, mechanical compatibility and degradability, is known as the green engineering material in the 21 st century as the lightest engineering metal material. Although the magnesium alloy has outstanding advantages, it has low wear resistance and poor corrosion resistance. These factors limit the wider application of magnesium alloys. The improvement of the corrosion resistance and the abrasion resistance of the magnesium alloy under different working conditions is a problem which needs to be solved by expanding the application of the magnesium alloy.

The plasma spraying technology is a novel multipurpose precise spraying method which is vigorously developed after flame spraying, has the characteristics of ultrahigh temperature, is convenient for spraying high-melting-point materials, has high particle spraying speed, compact coating, high bonding strength and low content of coating oxides and impurities, and has the advantages of thicker and harder plasma spraying layer, better corrosion prevention effect and the like compared with electroplating, electric brushes, carburizing and nitriding. Therefore, the plasma spraying technology has wide application in the modification of the surface of the metal matrix.

However, the coating prepared by plasma spraying is mainly mechanically combined with the substrate, so that the weak bonding strength is a defect that the plasma spraying is difficult to ignore. The coating has low bonding strength, is easy to fall off in the using process and is difficult to play a role in protecting the substrate, so the problem of weak bonding strength between the coating and the substrate needs to be solved to keep the coating to work stably for a long time.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a magnesium alloy surface plasma spraying Al/Al₂O₃The preparation method of the coating reduces thermal deformation caused by laser processing through the trapezoid sliding groove type texture prepared by precision processing, is easy to control the structural parameters of the trapezoid sliding groove, effectively increases the interlocking effect of the coating and the magnesium alloy substrate compared with other structures, and solves the technical problem of weak bonding force of the coating and the substrate in the prior art.

The scheme is realized by the following technical measures: plasma spraying Al/Al on magnesium alloy surface₂O₃The preparation method of the coating comprises the following steps:

(1) carrying out sand blasting treatment on the surface of the magnesium alloy substrate: removing oxide skin and impurities on the surface of the magnesium alloy substrate, and then removing scraps on the surface of the magnesium alloy substrate by using a blower or ultrasonic cleaning;

(2) processing a chute type texture on the surface of the magnesium alloy substrate subjected to sand blasting: uniformly processing a plurality of trapezoidal sliding grooves which are parallel to each other and narrow at the top and wide at the bottom on the surface of the magnesium alloy substrate subjected to sand blasting by using a precision machine tool, and cleaning the surface of the magnesium alloy substrate and residual scraps in the trapezoidal sliding grooves to increase the bonding area between the surface of the magnesium alloy substrate and a coating;

(3) preparing an Al coating: placing the magnesium alloy substrate treated in the step (2) in a heat-preserving table for preheating, wherein the temperature of the heat-preserving table is far lower than the melting temperature of the magnesium alloy substrate, and then plasma-spraying an Al coating on the surface of the magnesium alloy substrate, wherein the Al coating is a bonding layer;

(4) preparation of Al/Al₂O₃Coating: the magnesium alloy substrate which finishes the Al coating spraying in the step (3) is still placed in a heat preservation table for heat preservation, and Al/Al is plasma sprayed on the surface of the Al coating₂O₃Coating of said Al/Al₂O₃The coating is a working layer and Al/Al₂O₃The coating finishes spraying within three hours after the trapezoidal chute is processed.

Preferably, in the step (2), the distance between the lower bottoms of any two adjacent trapezoidal sliding chutes is 150 μm, the length of the upper bottom of each trapezoidal sliding chute is 38-42 μm, the height of each trapezoidal sliding chute is h, h is greater than 0 and less than 30 μm, and the lower bottom angle of each trapezoidal sliding chute is α, and α is greater than 75 degrees and less than 90 degrees.

Preferably, when the Al coating is sprayed in the step (3), Al powder with the particle size of 78-82 μm is adopted for spraying, when the spraying is carried out, the magnesium alloy substrate is placed in a heat preservation table for preheating, the temperature of the heat preservation table is 350 ℃, the spraying angle is an included angle of 135 degrees formed by the axis of the nozzle and the extension direction of the trapezoidal sliding chute, and gas in the trapezoidal sliding chute is discharged by utilizing gas flow sprayed by the nozzle;

preferably, Al/Al is sprayed in the step (4)₂O₃Al/Al is adopted for coating₂O₃And spraying the mixed powder, wherein the temperature of a heat preservation table is 350 ℃, the spraying voltage is 50V, the spraying current is 700A, the spraying distance is 90mm, argon is used as protective gas and powder feeding gas, the airflow pressure of the argon is 0.48MPa, the powder feeding amount is 30g/min, and the spraying angle is that a nozzle is vertical to the surface of the magnesium alloy matrix.

Preferably, the Al/Al₂O₃The mass ratio of the mixed powder is as follows: 40 mass percent of Al powder and 60 mass percent of Al₂O₃Powder, the grain diameter of the Al powder is 80 mu m, and the Al powder₂O₃The particle size of the powder was 50 μm.

Preferably, the thickness of the Al coating in the step (3) is 95-105 μm, and the Al/Al coating in the step (4)₂O₃The thickness of the coating was 195-205 μm.

Preferably, the thickness of the Al coating in the step (3) is 100 μm, and the Al/Al coating in the step (4)₂O₃The thickness of the coating was 200. mu.m.

Preferably, the spraying of the Al coating in step (3) is performed by using Al powder with a particle size of 80 μm.

Preferably, the magnesium alloy substrate is an AZ61 magnesium alloy sheet material with the thickness of 50mm multiplied by 6mm, and the thickness of the magnesium alloy substrate is 6 mm.

Preferably, 16# brown corundum sand is adopted during sand blasting in the step (1), the sand blasting distance is 50-70mm, the sand blasting angle is 60-80 degrees, the sand feeding is kept uniform, the sand blasting nozzle swings twice at a constant speed, and the moving speed is reduced when the sand is blasted to the edge of the magnesium alloy substrate.

The invention has the beneficial effects that: in the invention, regularly arranged trapezoid sliding grooves are manufactured on the surface of the magnesium alloy substrate after sand blasting through a precision machine tool, and an Al coating and Al/Al are sequentially sprayed on the surface of the magnesium alloy substrate through reasonably controlling the parameters of the trapezoid sliding grooves and the spraying parameters₂O₃Coating, Al coating can reduce magnesium alloy matrix and Al/Al₂O₃The difference of the physical properties of the coating and the good wettability with the magnesium alloy substrate, the molten Al powder particles are wetted and flow to enter the chute, the filling of the interior of the trapezoidal chute is realized as much as possible, the mechanical riveting effect of the coating and the magnesium alloy substrate is greatly increased, the spraying direction is an included angle formed by the axis of the nozzle and the extension direction of the trapezoidal chute of 135 degrees, the gas discharge is facilitated, the generation of a cavity at the bottom angle of the trapezoidal chute caused by the insufficient wettability of the molten Al particles can be reduced, the characteristics of the structure of the invention can be fully exerted, namely the interlocking effect of the trapezoidal chute on the bonding layer can be realized, the interlocking structure can increase the bonding area of the coating and the magnesium alloy substrate, the heating area of the molten particles on the magnesium alloy substrate can be increased, the heating effect of the molten metal entering the trapezoidal chute and the molten metal on the surface of the magnesium alloy substrate can be increased, and the metallurgical reaction of the molten metal and the magnesium alloy substrate can be increased, greatly improves the bonding strength of the coating and the magnesium alloy. The temperature of the magnesium alloy matrix is controlled to be 350 ℃, which is far lower than the melting temperature of the magnesium alloy matrix, so that the structural parameters of the trapezoidal chute are ensured not to be obviously changed in the spraying process. Plasma spraying Al/Al on the surface of the magnesium alloy₂O₃The preparation method of the coating can overcome the problem that the coating is easy to peel off from the joint surface, fully exerts the function of the cohesion of the coating, has low machining temperature, has small heat influence on the magnesium alloy matrix material, and reduces the deformation of the material. Therefore, compared with the prior art, the invention has prominent substantive features and remarkable progress, and the beneficial effects of the implementation are also obvious.

Drawings

FIG. 1 is a schematic flow chart of an embodiment of the present invention.

FIG. 2 is a schematic structural view of Al coating sprayed on the surface of a magnesium alloy substrate.

In the figure, 1-nozzle, 2-heat preservation platform, 3-magnesium alloy substrate, 4-trapezoidal chute, 5-Al coating, 6-Al/Al₂O₃And (4) coating.

Detailed Description

In order to clearly illustrate the technical features of the present solution, the following explains the present solution by way of specific embodiments and with reference to the accompanying drawings.

Plasma spraying Al/Al on magnesium alloy surface₂O₃The preparation method of the coating comprises the following steps.

(1) Carrying out sand blasting treatment on the surface of the magnesium alloy matrix 3: the method comprises the steps of putting a magnesium alloy matrix 3 into a sand blasting machine for sand blasting, wherein the magnesium alloy matrix 3 is an AZ61 magnesium alloy plate with the thickness of 50mm multiplied by 6mm, the thickness of the magnesium alloy matrix 3 is 6mm, 16# brown corundum sand is adopted during sand blasting treatment, the sand blasting distance is 50-70mm, the sand blasting angle is 60-80 degrees, sand feeding is kept uniform, a sand blasting nozzle swings twice at a constant speed, the moving speed is reduced when the sand blasting nozzle is blasted to the edge of the magnesium alloy matrix 3, oxide skin and impurities on the surface of the magnesium alloy matrix 3 are removed, then the magnesium alloy matrix 3 is cleaned by alcohol, a residual oxide film on the surface of the magnesium alloy matrix 3 after sand blasting is removed, and then a blower or ultrasonic cleaning is used for removing fragments on the surface of the magnesium alloy matrix 3.

(2) Processing a sliding groove type texture on the surface of the magnesium alloy matrix 3 subjected to sand blasting: a plurality of trapezoidal sliding chutes 4 which are parallel to each other and have narrow upper parts and wide lower parts are evenly processed on the surface of the magnesium alloy matrix 3 after sand blasting by adopting a precision machine tool, the distance between the lower bottoms of any two adjacent trapezoidal sliding chutes 4 is 150 mu m, the length of the upper bottom of the trapezoidal sliding chute 4 is 38-42 μm, the height of the trapezoidal sliding chute 4 is h, h is more than 0 and less than 30 μm, the lower bottom angle of the trapezoidal sliding chute is alpha, alpha is more than 75 degrees and less than 90 degrees, the junction of the trapezoidal sliding chute 4 is in smooth transition, the trapezoidal sliding chute 4 in the structural form has no sharp corner, can prevent the stress concentration between the coating and the magnesium alloy matrix 3, can also reduce the difficulty of filling fused particles, and after the processing is finished, the residual scraps on the surface of the magnesium alloy matrix 3 and in the trapezoidal sliding chute 4 are cleaned, so as to increase the bonding area between the surface of the magnesium alloy matrix 3 and the coating, and the spraying of the coating should be completed within 3 hours after the completion of the processing of the chute-shaped texture.

(3) Preparing an Al coating 5: placing the magnesium alloy matrix 3 treated in the step (2) in a heat preservation table 2 for preheating, and then plasma spraying an Al coating 5 on the surface of the magnesium alloy matrix 3. The temperature of the heat preservation table 2 is 350 ℃, the melting temperature of the magnesium alloy matrix 3 is 650 ℃, the temperature of the heat preservation table 2 is far lower than the melting temperature of the magnesium alloy matrix 3, so that the texture parameters of the surface of the magnesium alloy matrix 3 are basically unchanged in the spraying process, and the Al powder particles which are melted at high speed are sprayed on the magnesium alloy matrix 3 to have proper metallurgical reaction with the magnesium alloy matrix 3 and increase the wetting capacity of molten metal. The Al coating 5 is used as a bonding layer, so that the difference between the physical and mechanical properties of the magnesium alloy matrix 3 and the working layer can be reduced. Specifically, the magnesium alloy substrate 3 is placed in the heat preservation table 2 for preheating during spraying, the temperature of the heat preservation table 2 is 350 ℃, the spraying angle is an included angle of 135 degrees formed by the axis of the nozzle 1 and the extension direction of the trapezoidal sliding chute 4, gas in the trapezoidal sliding chute 4 is discharged by utilizing airflow sprayed by the nozzle 1, and the porosity in the sprayed coating is reduced. The thickness of the Al coating 5 is 95-105 μm, preferably the thickness of the Al coating 5 is 100 μm; the Al coating 5 is sprayed by using Al powder with the grain size of 78-82 mu m, preferably, the Al coating 5 is sprayed by using Al powder with the grain size of 80 mu m.

(4) Preparation of Al/Al₂O₃Coating 6: the magnesium alloy matrix 3 which finishes the spraying of the Al coating 5 in the step (3) is still placed in a heat preservation table 2 for heat preservation, the temperature of the heat preservation table 2 is 350 ℃, and Al/Al is plasma sprayed on the surface of the Al coating 5₂O₃Coating 6 of said Al/Al₂O₃The coating 6 being a working layer, Al/Al₂O₃The thickness of the coating 6 is 195-205 μm, preferably Al/Al₂O₃The thickness of the coating 6 is 200 μm and Al/Al₂O₃And the coating 6 is sprayed within three hours after the trapezoidal chute 4 is processed, the spraying voltage is 50V, the spraying current is 700A, the spraying distance is 90mm, the protective gas and the powder feeding gas adopt argon, the airflow pressure of the argon is 0.48MPa, the powder feeding amount is 30g/min, and the spraying angle is that the nozzle 1 is vertical to the surface of the magnesium alloy matrix 3. Spray Al/Al₂O₃Al/Al is used for the coating 6₂O₃Spraying the mixed powder, wherein the Al/Al is₂O₃The mass ratio of the mixed powder is as follows: 40 mass percent of Al powder and 60 mass percent of Al₂O₃Powder, the grain diameter of the Al powder is 80 mu m, and the Al powder₂O₃The powder has a particle size of 50 μm, and Al can be reduced by transversely swinging the mixed powder in a container with a large cross section₂O₃And the case where Al is not uniformly mixed due to the difference in density.

Technical features not described in the present invention can be implemented by the prior art, and are not described in detail herein. The present invention is not limited to the above-described embodiments, and variations, modifications, additions and substitutions which are within the spirit of the invention and the scope of the invention may be made by those of ordinary skill in the art are also within the scope of the invention.