Preparation process of compact zirconium boride coating and plasma spraying device

Abstract

The invention provides a preparation process of a compact zirconium boride coating and a plasma spraying device, and relates to the technical field of coating preparation. The preparation process comprises the following steps: preparation of a suspension: uniformly mixing a dispersion medium, ZrB2 powder, 10B-rich B powder, a binder and a dispersant to obtain the suspension; wherein the content of the ZrB2 powder is 2-10 wt.% of the total weight of the ZrB2 powder and the dispersion medium, the content of the B powder is 1-3 wt.% of the ZrB2 powder, the content of the binder is not higher than 0.5 wt.% of the ZrB2 powder, and the content of the dispersant is not higher than 0.5 wt.% of the ZrB2 powder; and plasma spraying: spraying the suspension on the surface of a to-be-sprayed workpiece in an inert atmosphere by adopting a plasma spraying technology to obtain the ZrB2 coating. The preparation cost of the ZrB2 coating is relatively low, the content of N and O in the coating is relatively low, the abundance of 10B is relatively high, and the effect is relatively good when the ZrB2 coating is used as an absorber.

Description

Technical Field

[0001] The invention relates to the technical field of coating preparation, and in particular to a preparation process of a zirconium boride dense coating and a plasma spraying device. Background Art

[0002] Extending the nuclear fuel cycle and improving the efficiency of nuclear fuel use are the main directions for improving the operating performance of commercial nuclear power reactors. Extending the cycle requires increasing the initial nuclear fuel enrichment, so more absorbent materials are needed to compensate for the excess initial reactivity. 2 It has the characteristics of high melting point, high strength, good conductivity and neutron capture. In the reactor, 10 B can adjust the reactivity of the reactor by absorbing thermal neutrons, so it is rich in 10 B's ZrB 2 The coating as an absorber can significantly improve the economic efficiency of the reactor; at the same time, the use of rich 10 B's ZrB 2 When the coating is used as an absorber, it is also required to strictly control the N and O content in the coating to ensure its effectiveness.

[0003] However, in the prior art, the preparation of ZrB 2 The cost of the coating is high, and the N and O content in the coating is high. 10 B is less abundant and less effective as an absorber. Summary of the invention

[0004] The purpose of the present invention is to provide a preparation process and plasma spraying device for a dense zirconium boride coating, so as to solve the existing problems in the preparation of ZrB 2 The cost of the coating is high, and the N and O content in the coating is high. 10 The abundance of B is low, so its effect as an absorber is poor.

[0005] In order to solve the above problems, the present invention provides a preparation process of a dense zirconium boride coating, comprising the following steps:

[0006] Preparation of suspension: Dispersing medium, ZrB 2 Powder, rich 10 B powder, a binder and a dispersant are uniformly mixed to obtain a suspension;

[0007] Among them, ZrB 2 The content of the powder is ZrB 2 2-10wt.% of the total weight of the powder and the dispersion medium, the content of B powder is ZrB 2 1~3wt.% of powder, the binder content is not higher than ZrB 2 0.5wt.% of powder, dispersant content is not higher than ZrB2 0.5wt.% of powder;

[0008] Plasma spraying: In an inert atmosphere, plasma spraying technology is used to spray the suspension onto the surface of the workpiece to obtain ZrB 2 coating.

[0009] Optionally, in the step of preparing the suspension, ZrB 2 Median particle size D of the powder 50 ≤3μm, median particle size D of B powder 50 ≤3μm.

[0010] Optionally, in the step of preparing the suspension, the dispersion medium, ZrB 2 Powder, rich 10 The B powder, binder and dispersant of B are weighed and mixed according to their respective contents to form a mixed liquid, and the mixed liquid is ball-milled until the particle dispersion effect in the mixed liquid reaches D 90 ≤5μm and D 50 ≤3 μm to obtain the suspension.

[0011] Optionally, ZrB 2 The thickness of the coating is 8 to 20 μm.

[0012] Optionally, the preparation process further comprises a step of treating the workpiece to be sprayed: using an organic solvent to clean the workpiece to be sprayed, sandblasting the cleaned workpiece to be sprayed using 150-220 mesh white corundum, and blowing the surface of the workpiece to be sprayed after sandblasting for the plasma spraying step;

[0013] The process conditions for sandblasting are a pressure of 0.1-0.3 MPa and a sandblasting distance of 60-80 mm; the pressure for air blowing is 0.3-0.5 MPa.

[0014] Optionally, in the step of preparing the suspension, deionized water, anhydrous ethanol or a mixture of the two is selected as the dispersion medium;

[0015] And / or, PVA is selected as the binder;

[0016] And / or, ammonium polyacrylate is selected as the dispersant.

[0017] Optionally, in the plasma spraying step, the process parameters of the plasma spraying technology are: spraying power is 80-120 kW, feeding rate is 20-50 ml / min, and spraying distance is 70-90 mm.

[0018] Optionally, in the plasma spraying step, the process chamber is evacuated until the pressure of the process chamber is less than 10 Pa, and an inert gas is filled into the process chamber until the pressure of the process chamber reaches 100-110 kPa to form the inert atmosphere.

[0019] The present invention also provides a plasma spraying device capable of performing the above-mentioned preparation process. The plasma spraying device comprises a process chamber and a vacuum pumping component. The process chamber is provided with an air supply port and an air exhaust port. The air supply port is used to connect to an inert gas source, and the air exhaust port is connected to a suction end of the vacuum pumping component. A carrier and a plasma spray gun are provided in the process chamber.

[0020] Optionally, the plasma spraying device also includes a gas circulation system, which includes a circulating air inlet and a circulating air outlet arranged in the process chamber, the circulating air inlet and the circulating air outlet are connected by a circulating pipeline, the circulating pipeline is located outside the process chamber, and the circulating pipeline is provided with a circulating pump and a dust filter.

[0021] In the preparation process provided by the present invention:

[0022] (1) ZrB sprayed by suspension plasma spraying technology 2 The coating has a higher density and there is no loss of raw materials compared to magnetron sputtering technology, thereby reducing the preparation cost.

[0023] (2) Rich in 10 The compensation of B powder can effectively improve the ZrB 2 In coating 10 B abundance to ensure that ZrB 2 The effect of a coating when applied to a nuclear fuel rod as an absorber.

[0024] (3) The setting of inert atmosphere can effectively reduce the ZrB caused by the plasma jet entrainment of air during plasma spraying. 2 High temperature oxidation and B ablation degree, thereby reducing ZrB 2 The N and O content in the coating increases 10 B abundance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 A schematic diagram of the process flow of the plasma spraying device provided by the present invention;

[0027] Figure 2 ZrB prepared according to the preparation process of Example 2 of the present invention 2 Cross-sectional scanning electron micrograph of the coating;

[0028] Figure 3 ZrB prepared according to the preparation process of Example 2 of the present invention 2 XRD pattern of coating;

[0029] Figure 4 ZrB prepared according to the preparation process of the comparative example 2 XRD patterns of coatings.

[0030] Description of reference numerals:

[0031] 100-process chamber; 110-carrier; 120-plasma spray gun; 130-air supply port; 140-exhaust port; 200-vacuum assembly; 210-vacuum valve; 300-gas circulation system; 310-circulating air inlet; 320-circulating air outlet; 330-circulating pipeline; 340-circulating pump; 350-dust filter; 410-air supply pipeline; 420-feeding pipeline; 500-cooling system; 510-water inlet; 520-water outlet; 600-control cabinet. DETAILED DESCRIPTION

[0032] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0034] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] This embodiment provides a preparation process of a dense zirconium boride coating, including a suspension preparation step and a plasma spraying step, as follows:

[0036] Preparation of suspension: Dispersing medium, ZrB 2 Powder, rich 10 B powder, a binder and a dispersant are mixed uniformly to obtain a suspension; wherein ZrB 2 The content of the powder is ZrB 2 2-10wt.% of the total weight of the powder and the dispersion medium, the content of B powder is ZrB 2 1~3wt.% of powder, the binder content is not higher than ZrB 2 0.5wt.% of powder, dispersant content is not higher than ZrB 2 0.5wt.% of the powder. ZrB 2 Powder as liquid raw material, rich in 10 B powder of B is added to the dispersion medium as a compensating raw material to form 10 In the mixed liquid with a high abundance of ZrB, a binder and a dispersant are added to the mixed liquid and mixed thoroughly to form a suspension with uniform and stable distribution of solid particles. 2 Powder, rich 10 There is no limitation on the order in which the B powder, the binder and the dispersant are added to the dispersion medium.

[0037] Plasma spraying: In an inert atmosphere, plasma spraying technology is used to spray the suspension onto the surface of the workpiece to obtain ZrB 2 The workpiece to be sprayed and the plasma spray gun are both in an inert atmosphere with a preset vacuum degree. The suspension plasma spraying technology (SPS) is used to evenly spray the suspension on the surface of the workpiece to be sprayed to form ZrB 2 coating.

[0038] Among them, in the preparation process of this application:

[0039] (1) ZrB sprayed by suspension plasma spraying technology 2The coating has a higher density and there is no loss of raw materials compared to magnetron sputtering technology, thereby reducing the preparation cost.

[0040] (2) Rich in 10 The compensation of B powder can effectively improve the ZrB 2 In coating 10 B abundance to ensure that ZrB 2 The effect of a coating when applied to a nuclear fuel rod as an absorber.

[0041] (3) The setting of inert atmosphere can effectively reduce the ZrB caused by the plasma jet entrainment of air during plasma spraying. 2 High temperature oxidation and B ablation degree, thereby reducing ZrB 2 The N and O content in the coating increases 10 B abundance.

[0042] Therefore, without changing the basic process principle of SPS, high density, low N and O content, high 10 B-abundance ZrB 2 coating, specifically, ZrB 2 In the coating, the porosity is ≤5%, the N element content is ≤0.16wt.%, the O element content is ≤1.1wt.%, and the B element content is 15-20wt.%. The coating is particularly suitable for use as an absorber on the surface of nuclear fuel rods.

[0043] Specifically, in the step of preparing the suspension, deionized water, anhydrous ethanol or a mixture of the two can be selected as the dispersion medium; PVA (Polyvinyl alcohol) can be selected as the binder; and ammonium polyacrylate can be selected as the dispersant.

[0044] Specifically, in this example, in the step of preparing the suspension, ZrB 2 Median particle size D of the powder 50 ≤3μm, median particle size D of B powder 50 ≤3μm. Select ZrB with this particle size 2 Powder and B powder are used as raw materials to prepare suspension, which can ensure the high temperature plasma jet process ZrB 2 The full melting of the powder and B powder effectively reduces the microscopic defects such as "splash" microcracks and unmelted particles formed when using large-size powder to prepare the coating, thereby further improving the ZrB 2 Density of coating.

[0045] In this embodiment, in the step of preparing the suspension, the following method can be used to mix the materials uniformly: 2 Powder, rich 10The B powder, binder and dispersant of B are weighed and mixed according to their respective contents to form a mixed liquid, and the mixed liquid is added to a ball mill for ball milling until the particle dispersion effect in the mixed liquid reaches D 90 ≤5μm and D 50 ≤3μm, thus obtaining the required suspension. Ball milling the mixed liquid can fully disturb the materials in the mixed liquid to make them fully and evenly mixed, and can also grind and crush the solid materials, so that ZrB 2 The particle size of the powder and B powder is smaller and the distribution is more uniform, which effectively reduces the presence of large-size particles, thereby further ensuring that ZrB 2 The density and uniformity of the coating.

[0046] Specifically, the solid phase particle size in the mixed liquid can be tested by a laser particle size analyzer.

[0047] Specifically, in this embodiment, ZrB 2 The thickness of the coating is 8 to 20 μm. 10 B enrichment and changes in ZrB 2 The effect of coating thickness is comparable. 10 Under the condition of constant B line density, compared with ZrB with a thickness of 4 to 6 μm 2 Coating, when ZrB 2 When the coating thickness increases to about 10μm, 10 B abundance can be increased by 40-50%; the present application prepares ZrB with a thickness of 8-20 μm 2 coating, while ensuring ZrB 2 In coating 10 B abundance, can significantly reduce ZrB 2 The preparation cost of the coating has significant economic benefits.

[0048] Optionally, in this embodiment, the preparation process also includes a step of treating the workpiece to be sprayed: using an organic solvent to clean the workpiece to be sprayed, using 150-220 mesh white corundum to sandblast the cleaned workpiece to be sprayed, and blowing the surface of the workpiece to be sprayed after sandblasting for the plasma spraying step; wherein the process conditions for sandblasting are a pressure of 0.1-0.3MPa, a sandblasting distance of 60-80mm; and a pressure of blowing for 0.3-0.5MPa. Specifically, an organic solvent such as anhydrous ethanol and acetone can be used to clean the workpiece to be sprayed to remove oil and other pollution on the surface of the workpiece to be sprayed; then the surface of the workpiece to be sprayed is sandblasted, and an air gun is used to remove the residual sand particles adhering to the surface of the workpiece to be sprayed after sandblasting, so as to improve the surface roughness of the workpiece to be sprayed, and correspondingly improve the firmness of the sprayed coating attached to the workpiece surface.

[0049] Specifically, in the plasma spraying step in this embodiment, the process parameters of the plasma spraying technology are: spraying power is 80-120 kW, feeding rate is 20-50 ml / min, and spraying distance is 70-90 mm.

[0050] In this embodiment, in the plasma spraying step, the required inert atmosphere can be obtained by the following operations: vacuuming the process chamber until the pressure of the process chamber is less than 10Pa, filling the process chamber with an inert gas until the pressure of the process chamber reaches 100-110kPa, thereby forming the required inert atmosphere.

[0051] This embodiment also provides a plasma spraying device capable of performing the above-mentioned preparation process, such as Figure 1 As shown, the plasma spraying device includes a process chamber 100 and a vacuum assembly 200. The process chamber 100 is provided with an air supply port 130 and an air exhaust port 140. The air supply port 130 is used to connect to an inert gas source, and the air exhaust port 140 is connected to a suction end of the vacuum assembly 200. A carrier 110 and a plasma spray gun 120 are provided in the process chamber 100.

[0052] When in use, the workpiece to be sprayed after sandblasting is mounted on the carrier 110, the air supply port 130 is connected to the inert gas source through the air supply line 410, and the plasma spray gun 120 is connected to the configured suspension through the feed line 420; then the process chamber 100 is closed, the vacuum pumping component 200 is turned on to pump the process chamber 100 until the pressure is less than 10Pa, the inert gas source is turned on to fill the process chamber 100 with inert gas as protective gas through the air supply port 130, and at the same time, the opening of the vacuum valve 210 at the front end of the vacuum pumping component 200 is adjusted to dynamically adjust the pressure in the process chamber 100 so that the internal pressure is maintained at 100-110kPa, thereby forming the required inert atmosphere.

[0053] Then, the plasma spray gun 120 is turned on, and the process parameters of plasma spraying are set as needed, specifically, the spraying power is 80-120 kW, the feeding rate is 20-50 ml / min, and the spraying distance is 70-90 mm; thus, a high density, low N, O content, and high 10 B-abundance ZrB 2 coating, specifically, ZrB 2 In the coating, the porosity is ≤5%, the N element content is ≤0.16wt.%, the O element content is ≤1.1wt.%, and the B element content is 15-20wt.%.

[0054] Specifically, the carrier 110 can be a rotatable turntable, and the bearing surface of the carrier 110 is provided with a plurality of stations for clamping the workpiece to be sprayed along its circumference; when in use, the plasma spray gun 120 is arranged toward the carrier 110, and the carrier 110 is rotated to spray different workpieces to be sprayed, thereby improving production efficiency.

[0055] In this embodiment, Figure 1 As shown, the plasma spraying device can also be provided with a gas circulation system 300, the gas circulation system 300 includes a circulation air inlet 310 and a circulation air outlet 320 arranged in the process chamber 100, the circulation air inlet 310 and the circulation air outlet 320 are connected through a circulation pipeline 330, the circulation pipeline 330 is located outside the process chamber 100, and the circulation pipeline 330 is provided with a circulation pump 340 and a dust filter 350. When setting up the gas circulation system 300, after the inert gas is filled into the process chamber 100 through the inert gas source to obtain the required inert atmosphere, the inert gas source can be turned off to stop the gas supply; during the spraying process, the circulation pump 340 can be turned on, and the circulation pump 340 drives the dust-carrying gas flow in the process chamber 100 to enter the circulation pipeline 330 through the circulation outlet 320, and then flows back to the process chamber 100 through the circulation pipeline 330 and the circulation inlet 310 after being filtered by the dust filter 350. In this way, on the basis of ensuring a clean inert atmosphere in the process chamber 100, the protective gas in the process chamber 100 is recycled, reducing the gas consumption caused by the need for the inert gas source to continuously deliver the protective gas during the spraying process, and correspondingly further reducing the production cost.

[0056] In this embodiment, the plasma spraying device may further include a cooling system 500 for cooling the process chamber 100. During the process, the cooling system 500 is used to cool the process chamber 100 to provide a suitable operating temperature for the plasma spray gun 120, the workpiece to be sprayed, and the carrier 110, thereby extending the service life of each component of the plasma spraying device and further reducing the production cost accordingly.

[0057] Specifically, Figure 1As shown, the cooling system 500 can be water-cooled, specifically including a water-cooling channel arranged inside the wall of the process chamber 100 or attached to the inner wall or outer wall of the wall, the water inlet end 510 of the water-cooling channel is connected to the water-cooling source through a water-cooling pipeline, and the water-cooling source continuously delivers cooling water to the water-cooling channel to achieve continuous cooling of the process chamber 100; or the water inlet end 510 and the water outlet end 520 of the water-cooling channel are connected through a water-cooling pipeline, and the water-cooling pipeline is equipped with a driving pump and a cooling component, and the driving pump can drive the water-cooling pipeline and the water-cooling channel to form a circulating channel in which the cooling water circulates, wherein the cooling water will be cooled in the process of flowing through the cooling component, and the process of flowing through the water-cooling channel can absorb heat and cool the process chamber 100, thereby realizing the recycling of cooling water.

[0058] In addition to cooling the process chamber 100, the cooling system 500 can also cool the circulating gas in the circulation pipeline 330 of the gas circulation system 300 to improve the cooling effect of the gas environment in the process chamber 100; of course, in addition to using the cooling system 500 to cool the circulating gas, a cooling component can also be directly integrated into the circulation pump 340, and the process of the circulating gas flowing through the circulation pump 340 can be cooled by the cooling component.

[0059] Specifically, Figure 1 As shown, a control cabinet 600 can be provided, in which a control module is communicatively connected to the plasma spray gun 120, the vacuum pumping component 200, the gas circulation system 300, the cooling system 500 and the inert gas source. By operating the control panel of the control cabinet 600, process control of the above components and systems can be achieved, including sequence control of the vacuum pumping component 200 and the inert gas source, pressure control in the process chamber 100, liquid supply control of the suspension, flow control of the protective gas, setting of process parameters of plasma spraying, etc.

[0060] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0061] Example 1

[0062] Step 1: Suspension preparation:

[0063] ① Using deionized water as the dispersion medium, the median particle size D 50 2.5μm ZrB 2 Powder is used as the raw material of liquid feed. According to the single preparation requirements, weigh ZrB 2 Powder and add a certain amount of deionized water to prepare the liquid solid content of 2.0wt.%; relative to ZrB 2 The powder mass was added with 0.1wt.% PVA as a binder, 0.1wt.% ammonium polyacrylate as a dispersant, and 1wt.% rich 10B powder is used as a compensating raw material to obtain a mixed liquid, wherein the mixture is rich in 10 The median particle size D of B powder 50 2.8μm;

[0064] ② Add the prepared mixed liquid into the ball mill for ball milling and dispersion, and use a laser particle size analyzer to test the particle size of the solid particles in the mixed liquid. 90 4.2μm, D 50 2.5μm, forming ZrB with good dispersion effect 2 Suspension.

[0065] Step 2: Processing of workpiece to be sprayed and controlled atmosphere adjustment:

[0066] ① Use anhydrous ethanol to clean the workpiece to be sprayed; then use 150-220 mesh white corundum to sandblast the cleaned workpiece to be sprayed, wherein the sandblasting process conditions are pressure 0.1MPa and sandblasting distance 80mm; then use an air gun to blow air on the surface of the workpiece to be sprayed to remove the residual sand particles adhering to the surface of the workpiece during the sandblasting process, wherein the blowing pressure is 0.3MPa;

[0067] ② Clamp the workpiece to be sprayed after sandblasting on the carrier inside the process chamber;

[0068] ③ Turn on the vacuum pumping assembly to evacuate the process chamber. When the pressure in the process chamber is less than 8.8 Pa, fill the process chamber with argon as a protective gas, turn on the circulation pump and adjust the opening of the vacuum valve on the front side of the vacuum pumping assembly to make the pressure in the process chamber reach and maintain at 100-110 kPa;

[0069] Step 3: Plasma spraying:

[0070] ① Turn on the plasma spray gun to spray the suspension onto the surface of the workpiece to be sprayed, thereby obtaining ZrB 2 The coating was sprayed with a spraying power of 120 kW, a feed rate of 50 ml / min, and a spraying distance of 70 mm.

[0071] The ZrB prepared in Example 1 2 The coating was tested, ZrB 2 The porosity of the coating is 5.0%, the thickness of the coating is 15 μm, the N element content in the coating is 0.16 wt.%, the O element content is 1.1 wt.%, and the B element content is 15 wt.%.

[0072] Example 2

[0073] Step 1: Suspension preparation:

[0074] ① Using deionized water as the dispersion medium, the median particle size D 50 2.2μm ZrB 2 Powder is used as the raw material of liquid feed. According to the single preparation requirements, weigh ZrB 2 Powder and add a certain amount of deionized water to prepare the liquid solid content of 10.0wt.%; relative to ZrB 2 The powder mass was added with 0.48wt.% PVA as a binder, 0.48wt.% ammonium polyacrylate as a dispersant, and 2wt.% rich 10 B powder is used as a compensating raw material to obtain a mixed liquid, wherein the mixture is rich in 10 The median particle size D of B powder 50 2.3μm;

[0075] ② Add the prepared mixed liquid into the ball mill for ball milling and dispersion, and use a laser particle size analyzer to test the particle size of the solid particles in the mixed liquid. 90 4.8μm, D 50 2.2μm, forming ZrB with good dispersion effect 2 Suspension.

[0076] Step 2: Processing of workpiece to be sprayed and controlled atmosphere adjustment:

[0077] ① Use anhydrous ethanol to clean the workpiece to be sprayed; then use 150-220 mesh white corundum to sandblast the cleaned workpiece to be sprayed, wherein the sandblasting process conditions are pressure 0.3MPa and sandblasting distance 60mm; then use an air gun to blow air on the surface of the workpiece to be sprayed to remove the residual sand particles adhering to the surface of the workpiece during the sandblasting process, wherein the blowing pressure is 0.3MPa;

[0078] ② Clamp the workpiece to be sprayed after sandblasting on the carrier inside the process chamber;

[0079] ③ Turn on the vacuum pumping assembly to evacuate the process chamber. When the pressure in the process chamber is less than 9.2 Pa, fill the process chamber with argon as a protective gas, turn on the circulation pump and adjust the opening of the vacuum valve on the front side of the vacuum pumping assembly to make the pressure in the process chamber reach and maintain at 100-110 kPa;

[0080] Step 3: Plasma spraying:

[0081] ① Turn on the plasma spray gun to spray the suspension onto the surface of the workpiece to be sprayed, thereby obtaining ZrB 2 The coating was sprayed with a spraying power of 80 kW, a feed rate of 20 ml / min, and a spraying distance of 90 mm.

[0082] The ZrB prepared in Example 2 2 The coating was tested, ZrB 2 The porosity of the coating is 4.5%, the thickness of the coating is 20 μm, the N element content in the coating is 0.09 wt.%, the O element content is 0.93 wt.%, and the B element content is 20 wt.%.

[0083] Figure 2 ZrB prepared according to the preparation process of Example 2 of the present invention 2 Cross-sectional scanning electron micrograph of the coating, showing an accuracy of 50 μm; Figure 2 It can be seen that the ZrB 2 The coating has higher density. Figure 3 ZrB prepared according to the preparation process of Example 2 of the present invention 2 XRD pattern of the coating; the XRD pattern only has weak ZrO 2 The diffraction peaks indicate that the degree of B ablation is low, which effectively reduces the ZrB 2 N content and O content in the coating.

[0084] Example 3

[0085] Step 1: Suspension preparation:

[0086] ① Using deionized water as the dispersion medium, the median particle size D 50 3.0μm ZrB 2 Powder is used as the raw material of liquid feed. According to the single preparation requirements, weigh ZrB 2 Powder and add a certain amount of deionized water to prepare the liquid solid content of 5.0wt.%; relative to ZrB 2 The powder mass was added with 0.28wt.% PVA as a binder, 0.28wt.% ammonium polyacrylate as a dispersant, and 2.5wt.% rich 10 B powder is used as a compensating raw material to obtain a mixed liquid, wherein the mixture is rich in 10 The median particle size D of B powder 50 2.5μm;

[0087] ② Add the prepared mixed liquid into the ball mill for ball milling and dispersion, and use a laser particle size analyzer to test the particle size of the solid particles in the mixed liquid. 90 4.6μm, D 50 2.8μm, forming ZrB with good dispersion effect 2 Suspension.

[0088] Step 2: Processing of workpiece to be sprayed and controlled atmosphere adjustment:

[0089] ① Use anhydrous ethanol to clean the workpiece to be sprayed; then use 150-220 mesh white corundum to sandblast the cleaned workpiece to be sprayed, wherein the sandblasting process conditions are pressure 0.2MPa and sandblasting distance 70mm; then use an air gun to blow air on the surface of the workpiece to be sprayed to remove the residual sand particles adhering to the surface of the workpiece during the sandblasting process, wherein the blowing pressure is 0.4MPa;

[0090] ② Clamp the workpiece to be sprayed after sandblasting on the carrier inside the process chamber;

[0091] ③ Turn on the vacuum pumping assembly to evacuate the process chamber. When the pressure in the process chamber is less than 8.8 Pa, fill the process chamber with argon as a protective gas, turn on the circulation pump and adjust the opening of the vacuum valve on the front side of the vacuum pumping assembly to make the pressure in the process chamber reach and maintain at 100-110 kPa;

[0092] Step 3: Plasma spraying:

[0093] ① Turn on the plasma spray gun to spray the suspension onto the surface of the workpiece to be sprayed, thereby obtaining ZrB 2 The coating was sprayed with a spraying power of 100 kW, a feed rate of 30 ml / min, and a spraying distance of 80 mm.

[0094] The ZrB prepared in Example 3 2 The coating was tested, ZrB 2 The porosity of the coating is 4.3%, the thickness of the coating is 10 μm, the N element content in the coating is 0.12 wt.%, the O element content is 0.9 wt.%, and the B element content is 17 wt.%.

[0095] Example 4

[0096] Step 1: Suspension preparation:

[0097] ① Deionized water and anhydrous ethanol were mixed in a mass ratio of 1:1 as the dispersion medium, and the median particle size D 50 2.8μm ZrB 2 Powder is used as the raw material of liquid feed. According to the single preparation requirements, weigh ZrB 2 Powder and add a certain amount of deionized water to prepare the liquid solid content of 3.0wt.%; relative to ZrB 2 The powder mass was added with 0.15wt.% PVA as a binder, 0.15wt.% ammonium polyacrylate as a dispersant, and 1.5wt.% rich 10 B powder is used as a compensating raw material to obtain a mixed liquid, wherein the mixture is rich in 10 The median particle size D of B powder50 2.6μm;

[0098] ② Add the prepared mixed liquid into the ball mill for ball milling and dispersion, and use a laser particle size analyzer to test the particle size of the solid particles in the mixed liquid. 90 3.8μm, D 50 2.6μm, forming ZrB with good dispersion effect 2 Suspension.

[0099] Step 2: Processing of workpiece to be sprayed and controlled atmosphere adjustment:

[0100] ① Use anhydrous ethanol to clean the workpiece to be sprayed; then use 150-220 mesh white corundum to sandblast the cleaned workpiece to be sprayed, wherein the sandblasting process conditions are pressure 0.3MPa and sandblasting distance 60mm; then use an air gun to blow air on the surface of the workpiece to be sprayed to remove the residual sand particles adhering to the surface of the workpiece during the sandblasting process, wherein the blowing pressure is 0.3MPa;

[0101] ② Clamp the workpiece to be sprayed after sandblasting on the carrier inside the process chamber;

[0102] ③ Turn on the vacuum pumping assembly to evacuate the process chamber. When the pressure in the process chamber is less than 8.8 Pa, fill the process chamber with argon as a protective gas, turn on the circulation pump and adjust the opening of the vacuum valve on the front side of the vacuum pumping assembly to make the pressure in the process chamber reach and maintain at 100-110 kPa;

[0103] Step 3: Plasma spraying:

[0104] ① Turn on the plasma spray gun to spray the suspension onto the surface of the workpiece to be sprayed, thereby obtaining ZrB 2 The coating was sprayed with a spraying power of 110 kW, a feed rate of 25 ml / min, and a spraying distance of 75 mm.

[0105] The ZrB prepared in Example 4 2 The coating was tested, ZrB 2 The porosity of the coating is 4.2%, the thickness of the coating is 8 μm, the N element content in the coating is 0.13 wt.%, the O element content is 0.92 wt.%, and the B element content is 16 wt.%.

[0106] Example 5

[0107] Step 1: Suspension preparation:

[0108] ① Using anhydrous ethanol as the dispersion medium and using the median particle size D 502.7μm ZrB 2 Powder is used as the raw material of liquid feed. According to the single preparation requirements, weigh ZrB 2 The powder was added with a certain amount of deionized water to prepare a liquid with a solid content of 8.0wt.%; relative to ZrB 2 The powder mass was added with 0.32wt.% PVA as a binder, 0.32wt.% ammonium polyacrylate as a dispersant, and 3wt.% rich 10 B powder is used as a compensating raw material to obtain a mixed liquid, wherein the mixture is rich in 10 The median particle size D of B powder 50 2.4μm;

[0109] ② Add the prepared mixed liquid into the ball mill for ball milling and dispersion, and use a laser particle size analyzer to test the particle size of the solid particles in the mixed liquid. 90 3.9μm, D 50 2.0μm, forming ZrB with good dispersion effect 2 Suspension.

[0110] Step 2: Processing of workpiece to be sprayed and controlled atmosphere adjustment:

[0111] ① Use anhydrous ethanol to clean the workpiece to be sprayed; then use 150-220 mesh white corundum to sandblast the cleaned workpiece to be sprayed, wherein the sandblasting process conditions are pressure 0.2MPa and sandblasting distance 80mm; then use an air gun to blow air on the surface of the workpiece to be sprayed to remove the residual sand particles adhering to the surface of the workpiece during the sandblasting process, wherein the blowing pressure is 0.3MPa;

[0112] ② Clamp the workpiece to be sprayed after sandblasting on the carrier inside the process chamber;

[0113] ③ Turn on the vacuum pumping assembly to evacuate the process chamber. When the pressure in the process chamber is less than 8.8 Pa, fill the process chamber with argon as a protective gas, turn on the circulation pump and adjust the opening of the vacuum valve on the front side of the vacuum pumping assembly to make the pressure in the process chamber reach and maintain at 100-110 kPa;

[0114] Step 3: Plasma spraying:

[0115] ① Turn on the plasma spray gun to spray the suspension onto the surface of the workpiece to be sprayed, thereby obtaining ZrB 2 The coating was sprayed with a spraying power of 90 kW, a feed rate of 40 ml / min, and a spraying distance of 85 mm.

[0116] The ZrB prepared in Example 5 2The coating was tested, ZrB 2 The porosity of the coating is 3.8%, the thickness of the coating is 12 μm, the N element content in the coating is 0.15 wt.%, the O element content is 0.97 wt.%, and the B element content is 18 wt.%.

[0117] Comparative Example

[0118] In the comparative example, the controlled atmosphere adjustment in step 2 of Example 2 is replaced by the atmospheric environment, and the process parameters of the remaining step 1 suspension preparation, the treatment of the workpiece to be sprayed in step 2, and the plasma spraying in step 3 are the same as those in Example 2.

[0119] ZrB prepared according to the comparative example 2 The coating has a porosity of 4.3%, a coating thickness of 13 μm, a N content of 1.06 wt.%, an O content of 8.7 wt.%, and a B content of 12 wt.%. Compared with the ZrB prepared in Example 2, 2 Coating, ZrB prepared in comparative example 2 The contents of N and O elements in the coating increased significantly, while the content of B element decreased.

[0120] Figure 4 ZrB prepared according to the preparation process of the comparative example 2 XRD pattern of the coating; there is obvious ZrO 2 The diffraction peaks indicate that B is significantly ablated, resulting in ZrB 2 The N and O contents in the coating exceed the standard.

[0121] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A process for preparing a dense zirconium boride coating, characterized in that: The following steps are involved: Preparation of suspension: Dispersing medium, ZrB2 powder, 10 B powder, a binder and a dispersant are uniformly mixed to obtain a suspension; The content of ZrB2 powder is 2-10wt.% of the total weight of ZrB2 powder and dispersion medium, the content of B powder is 1-3wt.% of ZrB2 powder, the content of binder is not higher than 0.5wt.% of ZrB2 powder, and the content of dispersant is not higher than 0.5wt.% of ZrB2 powder; Plasma spraying: Plasma spraying technology is used in an inert atmosphere to spray the suspension onto the surface of the workpiece to be sprayed to obtain a ZrB2 coating.

2. The preparation process according to claim 1, characterized in that: In the step of preparing the suspension, the median particle size D of the ZrB2 powder 50 ≤3μm, median particle size D of B powder 50 ≤3μm.

3. The preparation process according to claim 1, characterized in that: In the step of preparing the suspension, the dispersion medium, ZrB2 powder, and the 10 The B powder, binder and dispersant of B are weighed and mixed according to their respective contents to form a mixed liquid, and the mixed liquid is ball-milled until the particle dispersion effect in the mixed liquid reaches D 90 ≤5μm and D 50 ≤3 μm to obtain the suspension.

4. The preparation process according to claim 1, characterized in that: The thickness of the ZrB2 coating is 8 to 20 μm.

5. The preparation process according to claim 1, characterized in that: The preparation process also includes a step of treating the workpiece to be sprayed: using an organic solvent to clean the workpiece to be sprayed, using 150-220 mesh white corundum to sandblast the cleaned workpiece to be sprayed, and blowing the surface of the workpiece to be sprayed after sandblasting for the plasma spraying step; The process conditions for sandblasting are a pressure of 0.1-0.3 MPa and a sandblasting distance of 60-80 mm; the pressure for air blowing is 0.3-0.5 MPa.

6. The preparation process according to claim 1, characterized in that: In the step of preparing the suspension, deionized water, anhydrous ethanol or a mixture of the two is selected as the dispersion medium; And / or, PVA is selected as the binder; And / or, ammonium polyacrylate is selected as the dispersant.

7. The preparation process according to claim 1, characterized in that: In the plasma spraying step, the process parameters of the plasma spraying technology are: spraying power is 80-120 kW, feeding rate is 20-50 ml / min, and spraying distance is 70-90 mm.

8. The preparation process according to claim 1, characterized in that: In the plasma spraying step, the process chamber is evacuated until the pressure of the process chamber is less than 10 Pa, and an inert gas is filled into the process chamber until the pressure of the process chamber reaches 100-110 kPa to form the inert atmosphere.

9. A plasma spraying device, characterized in that: The preparation process according to any one of claims 1 to 8 can be performed, the plasma spraying device comprises a process chamber (100) and a vacuum pumping component (200), the process chamber (100) is provided with an air supply port (130) and an air suction port (140), the air supply port (130) is used to connect to an inert gas source, and the air suction port (140) is connected to a suction end of the vacuum pumping component (200); a carrier (110) and a plasma spray gun (120) are provided in the process chamber (100).

10. The plasma spraying device according to claim 9, characterized in that: The plasma spraying device further comprises a gas circulation system (300), wherein the gas circulation system (300) comprises a circulation air inlet (310) and a circulation air outlet (320) arranged in the process chamber (100), wherein the circulation air inlet (310) and the circulation air outlet (320) are connected via a circulation pipeline (330), wherein the circulation pipeline (330) is located outside the process chamber (100), and wherein the circulation pipeline (330) is provided with a circulation pump (340) and a dust filter (350).

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