A method for preparing plasma spray-coupled laser-strengthened coating

Abstract

The invention belongs to the technical field of surface treatment, and specifically relates to a preparation method of a plasma spraying coupled laser strengthening coating, which specifically comprises the following steps: step S1: substrate pretreatment: performing decontamination treatment and sandblasting treatment on the substrate; step S2: plasma spraying: selecting metal alloy powder as spraying raw material, preheating the pretreated substrate for the first time, setting parameters of plasma spraying equipment, starting the plasma spraying equipment to melt the metal alloy powder and accelerate it to impact the substrate surface to form a coating, and the coating thickness is controlled at 100-800μm; step S3: laser strengthening: preheating the substrate after plasma spraying for the second time, setting laser equipment parameters, laser scanning the surface of the substrate after plasma spraying, and cooling the substrate after laser scanning; step S4: post-treatment: performing surface treatment on the substrate after laser strengthening.

Description

Technical Field

[0001] The invention belongs to the technical field of surface treatment, and in particular relates to a method for preparing a plasma spraying coupled laser strengthening coating. Background Art

[0002] Plasma spraying is an important application in thermal spraying technology. Commonly used plasma spraying processes include atmospheric plasma spraying, controlled atmosphere plasma spraying, vacuum plasma spraying and solution plasma spraying. The main process principle is to melt the spraying particles into a molten or semi-molten state through the heat source of the plasma arc, and atomize them into numerous fine particles with the help of inert gas pressure. When these particles impact the surface of the substrate at high speed, they quickly cool and solidify by relying on the heat and kinetic energy contained in them, and form interlaced and overlapping coatings through wetting and spreading. The coating formed by plasma spraying has stable quality and will not change the thermophysical properties of the surface of the parts. It is suitable for spraying materials with high melting points.

[0003] However, the plasma spraying process also has defects. During the plasma spraying process, the spraying particles continuously impact the surface of the substrate, and are stacked and interlaced to form a coating. Therefore, the coating has a distinct layered structure. In addition, when the coating is formed, gas will remain between the layers of the coating, causing the coating to produce pores of varying sizes. Therefore, the coating structure is loose and the density is low.

[0004] Therefore, it is necessary to perform further surface treatment on the coating formed by plasma spraying to improve the quality of the coating. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a method for preparing a plasma spray-coupled laser-strengthened coating.

[0006] The present invention provides a method for preparing a plasma spray-coupled laser strengthening coating, which comprises the following steps:

[0007] Step S1: substrate pretreatment: performing decontamination and sandblasting treatment on the substrate;

[0008] Step S2: plasma spraying: select metal alloy powder as the spraying raw material, preheat the pretreated substrate for the first time, set the parameters of the plasma spraying equipment, start the plasma spraying equipment to melt the metal alloy powder and accelerate it to impact the substrate surface to form a coating, and the coating thickness is controlled at 100-800 μm;

[0009] Step S3: laser strengthening: preheating the substrate after plasma spraying for the second time, setting laser equipment parameters, laser scanning the surface of the substrate after plasma spraying, and cooling the substrate after laser scanning;

[0010] Step S4: Post-processing: performing surface treatment on the laser-strengthened substrate.

[0011] Furthermore, the metal alloy powder is a nickel-based alloy powder. In terms of weight percentage, the nickel-based alloy powder is Ni-30Co-20Cr-10Al-0.5Y, and the particle size range of the nickel-based powder is 25-120 μm.

[0012] Furthermore, the metal alloy powder is a cobalt-based alloy powder. In terms of weight percentage, the cobalt-based alloy powder is Co-32Co-15Cr-12Al-0.6Y, and the particle size range of the cobalt-based powder is 25-120 μm.

[0013] Further, in step S1, the substrate pretreatment includes the following steps:

[0014] Step S11: ultrasonically cleaning the substrate surface with acetone for 10-20 minutes;

[0015] Step S12: sand blasting the substrate surface with sand particles of 80-120 meshes at a pressure of 0.4-0.6 MPa.

[0016] Further, in step S2, the temperature of the first preheating is 100-150°C, and in step S3, the temperature of the second preheating is 150-200°C.

[0017] Further, in step S2, the parameters of the plasma spraying equipment are: spraying power is 30-40 kW, spraying distance is 90-130 mm, argon flow rate is 30-50 L / min, and hydrogen flow rate is 5-20 L / min.

[0018] Further, in step S3, the laser equipment parameters are: laser power is 400-600W, laser spot is 2-5mm, and the relationship between the laser scanning rate per second and the coating thickness satisfies the following formula:

[0019] Laser scanning rate per second = 0.8 / coating thickness.

[0020] Furthermore, in step S4, the surface of the laser-strengthened substrate is subjected to a vulcanization treatment, which specifically includes the following steps:

[0021] Step S41: decontaminating the surface of the laser-strengthened substrate;

[0022] Step S42: placing the sulfur source and the decontaminated substrate into a reaction furnace and introducing an inert gas;

[0023] Step S43: Keep introducing inert gas, heat the reaction furnace to 200-300° C. and maintain for 2 hours;

[0024] Step S44: wait for the reaction furnace to cool naturally to room temperature and take out the substrate.

[0025] Furthermore, the sulfur source is one of thiol or thioether.

[0026] Further, the sulfur source is hydrogen sulfide, and steps S42 and S43 are:

[0027] Step S42: placing the decontaminated substrate into a reaction furnace and introducing an inert gas;

[0028] Step S43: Keep introducing inert gas and hydrogen sulfide gas at the same time, heat the reaction furnace to 300-400° C. and maintain for 2 hours.

[0029] The method for preparing a plasma spray-coupled laser-strengthened coating provided by the present invention has at least the following beneficial effects:

[0030] 1. Use laser strengthening to treat the surface of plasma sprayed coating, so that there are fewer voids and internal oxides in the coating, the structure inside the coating is finer and more uniform, and the mechanical properties of the coating are improved;

[0031] 2. Plasma spraying and laser strengthening are coupled step by step. The surface treatment can be completed using plasma spraying equipment and laser heating equipment respectively, which makes the preparation process more flexible.

[0032] 3. By controlling the laser scanning rate, the coating heating depth and fine control can be flexibly achieved, which is conducive to the controllable processing of coatings of different thicknesses. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0034] The embodiment of the present invention provides a method for preparing a plasma spray-coupled laser strengthening coating, which comprises the following steps:

[0035] Step S1: substrate pretreatment: performing decontamination and sandblasting treatment on the substrate;

[0036] Step S2: plasma spraying: select metal alloy powder as the spraying raw material, preheat the pretreated substrate for the first time, set the parameters of the plasma spraying equipment, start the plasma spraying equipment to melt the metal alloy powder and accelerate it to impact the substrate surface to form a coating, and the coating thickness is controlled at 100-800 μm;

[0037] Step S3: laser strengthening: preheating the substrate after plasma spraying for the second time, setting laser equipment parameters, laser scanning the surface of the substrate after plasma spraying, and cooling the substrate after laser scanning;

[0038] Step S4: Post-processing: performing surface treatment on the laser-strengthened substrate.

[0039] In a preferred embodiment, the metal alloy powder is a nickel-based alloy powder. In terms of weight percentage, the nickel-based alloy powder is Ni-30Co-20Cr-10Al-0.5Y, and the particle size range of the nickel-based powder is 25-120 μm.

[0040] In a preferred embodiment, the metal alloy powder is a cobalt-based alloy powder. In terms of weight percentage, the cobalt-based alloy powder is Co-32Co-15Cr-12Al-0.6Y, and the particle size range of the cobalt-based powder is 25-120 μm.

[0041] In a further embodiment, in step S1, the substrate pretreatment comprises the following steps:

[0042] Step S11: ultrasonically cleaning the substrate surface with acetone for 10-20 minutes;

[0043] Step S12: sand blasting the substrate surface with sand particles of 80-120 meshes at a pressure of 0.4-0.6 MPa.

[0044] In a further embodiment, in step S2, the temperature of the first preheating is 100-150°C, and in step S3, the temperature of the second preheating is 150-200°C. Heating the substrate for pretreatment can promote "thermal activation" of the substrate surface (the reaction needs to overcome certain energy barriers (activation energy) to occur, and heating can provide enough energy for the reactant molecules to reach an activated state, so that the reaction can proceed smoothly), remove moisture, reduce temperature differences and reduce stress, so as to enhance the film-base bonding force; and preheating in stages in the two steps of plasma spraying and laser strengthening can, on the one hand, enhance the refinement of heat distribution (remove impurities with different precipitation temperatures on the surface of the substrate material in stages) and the uniformity of pretreatment performance; on the other hand, it is to accurately control the substrate temperature and prepare for further improvement of coating quality in the later stage.

[0045] In a further embodiment, in step S2, the parameters of the plasma spraying equipment are: spraying power is 30-40 kW, spraying distance is 90-130 mm, argon flow rate is 30-50 L / min, and hydrogen flow rate is 5-20 L / min.

[0046] In a further embodiment, in step S3, the laser equipment parameters are: laser power is 400-600W, laser spot is 2-5mm, and the relationship between the laser scanning rate per second and the coating thickness satisfies the following formula:

[0047] Laser scanning rate per second (unit: mm / s) = 0.8 / coating thickness (unit: mm).

[0048] In a further embodiment, in step S4, the surface of the laser-strengthened substrate is subjected to a vulcanization treatment, which specifically includes the following steps:

[0049] Step S41: decontaminating the surface of the laser-strengthened substrate;

[0050] Step S42: placing the sulfur source and the decontaminated substrate into a reaction furnace and introducing an inert gas;

[0051] Step S43: Keep introducing inert gas, heat the reaction furnace to 200-300° C. and maintain for 2 hours;

[0052] Step S44: wait for the reaction furnace to cool naturally to room temperature and take out the substrate.

[0053] In further embodiments, the sulfur source is one of a thiol or a thioether.

[0054] In other embodiments, the sulfur source is hydrogen sulfide, and steps S42 and S43 are changed to:

[0055] Step S42: placing the decontaminated substrate into a reaction furnace and introducing an inert gas;

[0056] Step S43: Keep introducing inert gas and hydrogen sulfide gas at the same time, heat the reaction furnace to 300-400° C. and maintain for 2 hours.

[0057] In a further embodiment, the laser-strengthened coating is further surface treated. By vulcanizing the coating, a vulcanized lubricating film can be further formed on the surface of the coating, so that when the coating is rubbed, the friction wear and friction coefficient of the coating are reduced, thereby increasing the life of the coating.

[0058] To better illustrate the solutions of the present invention, the following are specific embodiments.

[0059] Example 1

[0060] The preparation method of plasma spray-coupled laser-strengthened coating adopts the following steps:

[0061] Substrate pretreatment: decontamination and sandblasting of the substrate;

[0062] Plasma spraying: the pretreated substrate was preheated for the first time at a heating temperature of 150°C. The spraying raw material was a nickel-based alloy powder of Ni-30Co-20Cr-10Al-0.5Y. The parameters of the plasma spraying equipment were set to spray power of 30kW, spray distance of 90mm, argon flow rate of 30L / min, and hydrogen flow rate of 5L / min. The plasma spraying equipment was started for spraying, and the coating thickness was controlled to be 100μm.

[0063] Laser strengthening: preheat the substrate after plasma spraying for the second time, the heating temperature is 200°C, the laser equipment parameters are set, the laser power is 400W, the laser spot is 2mm, the laser scanning rate is 8mm / s, the surface of the substrate after plasma spraying is laser scanned, and the substrate after laser scanning is cooled;

[0064] Post-treatment: Use mercaptan to perform sulfurization treatment on the surface of the substrate.

[0065] Example 2

[0066] The preparation method of plasma spray-coupled laser-strengthened coating adopts the following steps:

[0067] Substrate pretreatment: decontamination and sandblasting of the substrate;

[0068] Plasma spraying: the pretreated substrate was preheated for the first time at a heating temperature of 150°C. The spraying raw material was a nickel-based alloy powder of Ni-30Co-20Cr-10Al-0.5Y. The parameters of the plasma spraying equipment were set to spray power of 30kW, spray distance of 90mm, argon flow rate of 30L / min, and hydrogen flow rate of 5L / min. The plasma spraying equipment was started for spraying, and the coating thickness was controlled to be 100μm.

[0069] Laser strengthening: preheat the substrate after plasma spraying for the second time, the heating temperature is 200°C, the laser equipment parameters are set, the laser power is 600W, the laser spot is 2mm, the laser scanning rate is 8mm / s, the surface of the substrate after plasma spraying is laser scanned, and the substrate after laser scanning is cooled;

[0070] Post-treatment: Use mercaptan to perform sulfurization treatment on the surface of the substrate.

[0071] Example 3

[0072] The preparation method of plasma spray-coupled laser-strengthened coating adopts the following steps:

[0073] Substrate pretreatment: decontamination and sandblasting of the substrate;

[0074] Plasma spraying: the pretreated substrate was preheated for the first time at a heating temperature of 150°C. The spraying raw material was a nickel-based alloy powder of Ni-30Co-20Cr-10Al-0.5Y. The parameters of the plasma spraying equipment were set to spray power of 30kW, spray distance of 90mm, argon flow rate of 30L / min, and hydrogen flow rate of 5L / min. The plasma spraying equipment was started for spraying, and the coating thickness was controlled to be 100μm.

[0075] Laser strengthening: preheat the substrate after plasma spraying for the second time, the heating temperature is 200°C, the laser equipment parameters are set, the laser power is 400W, the laser spot is 5mm, the laser scanning rate is 8mm / s, the surface of the substrate after plasma spraying is laser scanned, and the substrate after laser scanning is cooled;

[0076] Post-treatment: Use mercaptan to perform sulfurization treatment on the surface of the substrate.

[0077] Example 4

[0078] The preparation method of plasma spray-coupled laser-strengthened coating adopts the following steps:

[0079] Substrate pretreatment: decontamination and sandblasting of the substrate;

[0080] Plasma spraying: the pretreated substrate was preheated for the first time at a heating temperature of 150°C. The spraying raw material was Co-32Co-15Cr-12Al-0.6Y cobalt-based alloy powder. The parameters of the plasma spraying equipment were set to spray power of 30kW, spray distance of 90mm, argon flow rate of 30L / min, and hydrogen flow rate of 5L / min. The plasma spraying equipment was started for spraying, and the coating thickness was controlled to be 100μm.

[0081] Laser strengthening: preheat the substrate after plasma spraying for the second time, the heating temperature is 200°C, the laser equipment parameters are set, the laser power is 400W, the laser spot is 2mm, the laser scanning rate is 8mm / s, the surface of the substrate after plasma spraying is laser scanned, and the substrate after laser scanning is cooled;

[0082] Post-treatment: Use mercaptan to perform sulfurization treatment on the surface of the substrate.

[0083] Example 5

[0084] The preparation method of plasma spray-coupled laser-strengthened coating adopts the following steps:

[0085] Substrate pretreatment: decontamination and sandblasting of the substrate;

[0086] Plasma spraying: the pretreated substrate was preheated for the first time at a heating temperature of 150°C. The spraying raw material was a nickel-based alloy powder of Ni-30Co-20Cr-10Al-0.5Y. The parameters of the plasma spraying equipment were set to spray power of 30kW, spray distance of 90mm, argon flow rate of 30L / min, and hydrogen flow rate of 5L / min. The plasma spraying equipment was started for spraying, and the coating thickness was controlled to be 400μm.

[0087] Laser strengthening: preheat the substrate after plasma spraying for the second time, the heating temperature is 200°C, the laser equipment parameters are set, the laser power is 400W, the laser spot is 2mm, the laser scanning rate is 2mm / s, the surface of the substrate after plasma spraying is laser scanned, and the substrate after laser scanning is cooled;

[0088] Post-treatment: Use mercaptan to perform sulfurization treatment on the surface of the substrate.

[0089] Example 6

[0090] The preparation method of plasma spray-coupled laser-strengthened coating adopts the following steps:

[0091] Substrate pretreatment: decontamination and sandblasting of the substrate;

[0092] Plasma spraying: the pretreated substrate was preheated for the first time at a heating temperature of 150°C. The spraying raw material was a nickel-based alloy powder of Ni-30Co-20Cr-10Al-0.5Y. The parameters of the plasma spraying equipment were set to spray power of 30kW, spray distance of 90mm, argon flow rate of 30L / min, and hydrogen flow rate of 5L / min. The plasma spraying equipment was started for spraying, and the coating thickness was controlled to be 800μm.

[0093] Laser strengthening: preheat the substrate after plasma spraying for the second time, the heating temperature is 200°C, the laser equipment parameters are set, the laser power is 400W, the laser spot is 2mm, the laser scanning rate is 1mm / s, the surface of the substrate after plasma spraying is laser scanned, and the substrate after laser scanning is cooled;

[0094] Post-treatment: Use mercaptan to perform sulfurization treatment on the surface of the substrate.

[0095] Example 7

[0096] The preparation method of plasma spray-coupled laser-strengthened coating adopts the following steps:

[0097] Substrate pretreatment: decontamination and sandblasting of the substrate;

[0098] Plasma spraying: the pretreated substrate was preheated for the first time at a heating temperature of 150°C. The spraying raw material was a nickel-based alloy powder of Ni-30Co-20Cr-10Al-0.5Y. The parameters of the plasma spraying equipment were set to spray power of 30kW, spray distance of 90mm, argon flow rate of 30L / min, and hydrogen flow rate of 5L / min. The plasma spraying equipment was started for spraying, and the coating thickness was controlled to be 100μm.

[0099] Laser strengthening: preheat the substrate after plasma spraying for the second time, the heating temperature is 200°C, the laser equipment parameters are set, the laser power is 400W, the laser spot is 2mm, the laser scanning rate is 8mm / s, the surface of the substrate after plasma spraying is laser scanned, and the substrate after laser scanning is cooled;

[0100] Post-treatment: Use hydrogen sulfide to perform sulfurization treatment on the surface of the substrate.

[0101] Comparative Example 1

[0102] Except that the laser scanning rate is set to 2 mm / s, the rest is the same as Example 1.

[0103] Comparative Example 2

[0104] Except that the laser scanning rate is set to 16 mm / s, the rest is the same as Example 1.

[0105] Comparative Example 3

[0106] Except that the laser power is set to 800 W, the rest is the same as Example 1.

[0107] Comparative Example 4

[0108] Except that the laser spot is set to 1 mm, the rest is the same as Example 1.

[0109] Comparative Example 5

[0110] Compared with Example 1, Comparative Example 5 does not undergo surface vulcanization treatment, and the rest is the same as Example 1.

[0111] The coatings of the substrates treated in Examples 1-7 and Comparative Examples 1-5 were subjected to characterization tests, including determination of the porosity and internal oxide ratio of the coating (determined by microscopic imaging, three measurements were performed on each sample, and the average value was taken), coating bonding strength test (GB / T 8642-2002), and friction coefficient test (dry sliding friction and wear test, the instrument was a friction and wear tester MFT500).

[0112] Table 1 Test results of various embodiments and comparative examples

[0113]

[0114] It can be concluded from the above table: by comparing Example 1 and Example 2 with Comparative Example 3, it can be seen that the laser power of laser strengthening is appropriately increased, and the bonding strength of the strengthened coating is slightly improved. When the laser power is too high, the original structure of the coating will be seriously damaged, resulting in coating damage; by comparing Example 1 and Example 3 with Comparative Example 4, it can be seen that when the laser spot size of laser scanning is appropriately increased, the bonding strength of the coating can be slightly improved. When the spot size is too small, the laser strengthening cannot be fully achieved, the coating voids and the proportion of internal oxides in the coating increase, and the coating bonding strength becomes lower; by comparing Example 1 with Example 4, it can be seen that the preparation method of the present invention can have a good effect on the coatings formed by nickel-based alloy powders and cobalt-based alloy powders; by comparing Example 1 and Example 5 Compared with Example 6, it can be seen that when the ratio of laser scanning rate to coating thickness is met, an increase in coating thickness will cause a slight decrease in coating performance, but it will still remain within a good range; by comparing Example 1, Example 7 and Comparative Example 5, it can be seen that for coatings prepared from the same nickel-based alloy powder, after surface vulcanization treatment with thiol and hydrogen sulfide, the friction coefficient of the coating is small, while without surface vulcanization treatment, the friction coefficient of the coating is significantly increased; by comparing Example 1, Comparative Example 1 and Comparative Example 2, it can be seen that when the coating thickness is the same, a too fast laser scanning rate will cause the laser to be unable to effectively heat the coating, so that the properties of the coating are not fully enhanced, while a too slow laser scanning rate will cause the laser to over-heat the coating, thereby completely destroying the properties of the coating.

[0115] The present invention couples plasma spraying and laser strengthening step by step. On the one hand, the thickness of the melted coating can be regulated by flexibly controlling the laser scanning rate. The coating after laser heating and cooling forms a dense coating with less voids and internal oxides, fine and uniform structure in the coating, and high coating bonding strength. On the other hand, thanks to the step-by-step coupling of plasma spraying and laser heating, conventional atmospheric plasma spraying equipment and laser heating equipment can be used to flexibly realize the efficient preparation of dense coatings, which is conducive to industrial applications. Furthermore, surface vulcanization treatment of the laser-strengthened coating can reduce the friction coefficient of the coating and effectively increase the life of the coating.

[0116] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing a plasma spray-coupled laser-strengthened coating, characterized in that: The following steps are involved: Step S1: substrate pretreatment: performing decontamination and sandblasting treatment on the substrate; Step S2: plasma spraying: select metal alloy powder as the spraying raw material, preheat the pretreated substrate for the first time, set the parameters of the plasma spraying equipment, start the plasma spraying equipment to melt the metal alloy powder and accelerate it to impact the substrate surface to form a coating, and the coating thickness is controlled at 100-800 μm; Step S3: laser strengthening: preheating the substrate after plasma spraying for the second time, setting laser equipment parameters, laser scanning the surface of the substrate after plasma spraying, and cooling the substrate after laser scanning; Step S4: post-processing: performing surface treatment on the substrate after laser strengthening; In step S2, the temperature of the first preheating is 100-150°C, and in step S3, the temperature of the second preheating is 150-200°C; In step S3, the laser equipment parameters are: laser power is 400-600W, laser spot is 2-5mm, and the relationship between the laser scanning rate per second and the coating thickness satisfies the following formula: Laser scanning rate per second = 0.8 / coating thickness Where: the unit of laser scanning rate per second is mm / s; the unit of coating thickness is mm; In step S4, the surface of the laser-strengthened substrate is subjected to a vulcanization treatment, which specifically includes the following steps: Step S41: decontaminating the surface of the laser-strengthened substrate; Step S42: placing the sulfur source and the decontaminated substrate into a reaction furnace and introducing an inert gas; Step S43: Keep introducing inert gas, heat the reaction furnace to 200-300° C. and maintain for 2 hours; Step S44: wait for the reaction furnace to cool naturally to room temperature and take out the substrate.

2. The method for preparing a plasma spray-coupled laser strengthening coating according to claim 1, characterized in that: The metal alloy powder is a nickel-based alloy powder. In terms of weight percentage, the nickel-based alloy powder is Ni-30Co-20Cr-10Al-0.5Y, and the particle size range of the nickel-based powder is 25-120 μm.

3. The method for preparing a plasma spray-coupled laser strengthening coating according to claim 1, characterized in that: The metal alloy powder is a cobalt-based alloy powder. In terms of weight percentage, the cobalt-based alloy powder is Co-32Co-15Cr-12Al-0.6Y, and the particle size range of the cobalt-based powder is 25-120 μm.

4. The method for preparing a plasma spray-coupled laser strengthening coating according to claim 1, characterized in that: In step S1, the substrate pretreatment includes the following steps: Step S11: ultrasonically cleaning the substrate surface with acetone for 10-20 minutes; Step S12: sand blasting the substrate surface with sand particles of 80-120 meshes at a pressure of 0.4-0.6 MPa.

5. The method for preparing a plasma spray-coupled laser strengthening coating according to claim 1, characterized in that: In step S2, the parameters of the plasma spraying equipment are: spraying power is 30-40 kW, spraying distance is 90-130 mm, argon flow rate is 30-50 L / min, and hydrogen flow rate is 5-20 L / min.

6. The method for preparing a plasma spray-coupled laser strengthening coating according to claim 1, characterized in that: The sulfur source is one of a thiol or a thioether.

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