High-temperature-resistant SiC coating material and coating preparation method

Abstract

The application provides a high-temperature-resistant SiC coating material and a coating preparation method, and belongs to the technical field of thermal spraying surface engineering. The high-temperature-resistant SiC coating material has SiC as a core, Si as a cladding layer shell, Si as a bonding phase, and SiC as a base phase. The SiC matches the thermal expansion coefficient of a high-strength alloy steel base body, and the heat resistance can reach 1500-1600 DEG C, so that the coating has excellent thermal cycle life on the high-strength alloy steel base body. Meanwhile, Si atoms are deposited on the surface of SiC particles to form a cladding layer, which can play a role as a bonding phase in the thermal spraying process and generate SiO2 to prevent the sintering densification of the SiC base phase under a high-temperature service environment, so that the coating always maintains excellent performance and meets the long-life use requirement.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thermal spraying surface engineering, in particular to a high-temperature-resistant SiC coating material and a coating preparation method. BACKGROUND

[0002] SiC has excellent physical and chemical properties such as high melting point, high hardness, corrosion resistance, oxidation resistance, etc., especially in the range of 1800-2000℃, it has good ablation resistance. In the field of high-end equipment manufacturing, SiC ceramic wear-resistant coating is widely used in microelectronics, aviation, aerospace and other fields. For example, in the semiconductor industry, SiC is the core material for the development of the third generation of semiconductor devices, mainly used in the production of semiconductor silicon boats and other core components.

[0003] It should be noted that in the process of preparing the coating by thermal spraying, SiC as a ceramic hard phase must be added with a binder, and the commonly used binder is Co or Ni material, which has fatal problems for the semiconductor industry, such as easy introduction of pollutants, poor high-temperature thermal stability of the coating, etc. At present, the actual service temperature of SiC ceramic reinforced coating is 1200℃, which cannot meet the requirements of the semiconductor and electronic industry, and it is extremely necessary to improve the high-temperature oxidation resistance of the coating. It is reported that the commonly used method to improve the high-temperature oxidation resistance of such coating is to use laser to prepare Ni625+SiC+Ni(WC) multi-element ceramic modified high-temperature oxidation resistant layer (patent No. CN202310038375.6), and to use thermal spraying SiC+Si+BN composite powder to prepare high-temperature sealing coating, with a maximum service temperature of 1350℃, which can be used in aero-engines and gas turbines (authorized patent No. CN201810200025.4), but there are still disadvantages such as high cost, complex process, easy introduction of impurities, and low service temperature, which cannot be applied to ultra-high temperature working conditions of 1500-1600℃. Long-term use under such service conditions may cause local damage to the coating surface. The traditional SiC coating material and its preparation method cannot meet the requirements of such high service temperature, and how to improve the purity and high-temperature stability of SiC coating, and determine the appropriate powder preparation technology and coating preparation process, is the key to the research in this field.

[0004] Therefore, it is of great practical significance to provide a raw material and a preparation method for improving the high-temperature stability of SiC coating. SUMMARY

[0005] The application aims to provide a high-temperature-resistant SiC coating material and a coating preparation method, wherein the high-temperature-resistant SiC coating material takes SiC as a core, takes Si as a bonding phase, and wraps the SiC outside with the Si as the bonding phase, thereby ensuring the oxidation resistance of the coating in a high-temperature environment of 1500-1600 DEG C; meanwhile, the Si atoms are deposited on the surface of the SiC particles to form a coating layer, which can play a role as a bonding phase in the thermal spraying process and can generate SiO2 to prevent the sintering and densification of the SiC base phase in a high-temperature service environment, so that the coating always maintains excellent performance and meets the long-life use requirement.

[0006] In order to achieve the above-mentioned application purposes, the application provides the following technical solutions.

[0007] The application provides a high-temperature-resistant SiC coating material, which comprises the following components in mass percentage: Si 8.0-15.0%, and the balance is SiC.

[0008] The high-temperature-resistant SiC coating material is a composite particle of SiC and Si.

[0009] The composite particle comprises a SiC core and a Si coating layer shell.

[0010] Preferably, the particle size of the composite particle is 30-50 mu m, and the sphericity is 99%-100%; the thickness of the Si coating layer shell is 5-8 mu m.

[0011] Preferably, the purity of the composite particle is 99.9999%.

[0012] The application further provides a preparation method of the high-temperature-resistant SiC coating material.

[0013] SiC seed crystals are added into a rotating fluidized bed, SiH4 is introduced, and the SiH4 is cracked into H2 and Si atoms under a first temperature condition;

[0014] Under a second temperature condition, the SiC seed crystals are blown up and boiled by H2 with a pressure of 0.1 MPa, and the Si atoms are deposited on the surface of the SiC particles to form a Si coating layer shell within 1-2 hours, so as to obtain a composite particle taking SiC as a core and taking Si as a coating layer shell;

[0015] The composite particle taking SiC as a core and taking Si as a coating layer shell is settled to the low end under the action of the rotating fluidized bed, is cooled and collected, and the high-temperature-resistant SiC coating material is obtained.

[0016] Preferably, the first temperature is 550-650 DEG C, and the second temperature is 500-600 DEG C.

[0017] The application further provides a high-temperature-resistant SiC coating layer comprising the high-temperature-resistant SiC coating material or the high-temperature-resistant SiC coating material prepared by the preparation method of the high-temperature-resistant SiC coating material.

[0018] Preferably, the high-temperature-resistant SiC coating layer is prepared by using ordinary plasma spraying or supersonic plasma thermal spraying technology.

[0019] The application further provides a preparation method of the high-temperature-resistant SiC coating layer, comprising the following steps:

[0020] (1) drying the high-temperature-resistant SiC coating material;

[0021] (2) pretreating the substrate workpiece;

[0022] (3) spraying the high-temperature-resistant SiC coating material on the surface of the pretreated substrate by using ordinary plasma spraying or supersonic plasma thermal spraying method, to obtain a substrate workpiece with a coating layer;

[0023] (4) nitriding the substrate workpiece with the coating layer in an N2 furnace, so that a mixed phase of SiC, Si and SiN is formed in the coating layer, to obtain the high-temperature-resistant SiC coating layer.

[0024] The pretreatment comprises roughening, cleaning and drying;

[0025] The roughening is roughening by using high-purity SiC;

[0026] The spraying conditions are as follows: power 28-35 kW, cooling gas flow rate 80-100 lpm, spraying distance 80-110 mm, powder feeding rate 30-40 g / min, and coating layer thickness 250-300 µm;

[0027] The nitriding temperature is 1100-1200 ℃, and the time is 200-300 mins.

[0028] Preferably, the proportion of each phase of SiC, Si and SiN in the high-temperature-resistant SiC coating layer is 85%:5%:10% to 85%:4%:11%.

[0029] Preferably, the porosity of the high-temperature-resistant SiC coating layer is 3%-7%, the thickness of the high-temperature-resistant SiC coating layer is 250-350 µm, and the adhesion of the high-temperature-resistant SiC coating layer to the substrate is 23-38 MPa.

[0030] Compared with the prior art, the technical scheme of the application has the following beneficial effects:

[0031] (1) The high-temperature-resistant SiC coating material described in the application adds elemental Si, and Si is wrapped on the surface of SiC as a coating shell, so as to ensure the oxidation resistance of the coating in a high-temperature environment of 1500-1600℃; at the same time, Si atoms are deposited on the surface of SiC particles to form a coating layer, which can play a role as a binder phase in the thermal spraying process and can generate SiO2 to prevent the sintering and densification of the SiC matrix phase in a high-temperature service environment, so that the coating always maintains excellent performance and meets the long service life requirement.

[0032] (2) The preparation process of the high-temperature-resistant SiC coating material described in the application is simple and efficient, and the formed SiC ceramic wear-resistant coating is defect-free and has good adhesion to the substrate.

[0033] (3) In the high-temperature-resistant SiC coating material described in the application, Si replaces the traditional Co and Ni materials as a binder, and is prepared into a high-temperature-resistant high-purity coating by a common plasma spraying or supersonic plasma thermal spraying process, and the highest use temperature can reach 1600℃, which is 400℃ higher than the use temperature of the existing SiC high-temperature coating. In a 1600℃ thermal shock experiment, the thermal shock resistance is greater than 200 times, the coating has good matching with the substrate material, can fully exert the high-temperature resistance advantage of ceramic materials, and has a wide application in the new generation of semiconductor industry, aeroengines and gas turbines. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is a preparation flowchart of the high-temperature-resistant SiC coating material described in the application;

[0035] In the figure, 1 is a SiC seed crystal, 2 is SiH4, 3 is H2 obtained by the decomposition of SiH4, 4 is Si atoms obtained by the decomposition of SiH4, 5 is H2, and 6 is Si-SiC particles.

[0036] Figure 2 is a preparation method schematic diagram of the high-temperature-resistant SiC coating described in the application;

[0037] Figure 3 is a structure schematic diagram of the high-temperature-resistant SiC coating described in the application;

[0038] Figure 4 is a powder micro-morphology diagram and energy spectrum point scanning diagram obtained by the preparation method of Example 1 of the application;

[0039] Figure 5 is a micro-morphology diagram and energy spectrum line scanning diagram of the high-temperature-resistant SiC coating material prepared in Example 1 of the application;

[0040] Figure 6 is a trace impurity result of the high-temperature-resistant SiC coating material prepared in Example 1 of the application measured by GDMS (glow discharge mass spectrometry).

[0041] Figure 7 Figure 1 is a micrograph of a high-temperature-resistant SiC coating material prepared according to Embodiment 4 of the present application, and Figure 2 is a point scanning result of the micrograph. DETAILED DESCRIPTION

[0042] The present application provides a high-temperature-resistant SiC coating material, comprising the following components in mass percentage: Si 8.0-15.0%, and the balance being SiC.

[0043] The high-temperature-resistant SiC coating material is a composite particle of SiC and Si.

[0044] The composite particle comprises a SiC inner core and a Si cladding layer shell.

[0045] In the present application, the particle size of the composite particle is preferably 30-50 μm, further preferably 40-50 μm, and more preferably 40-45 μm.

[0046] In the present application, the sphericity of the composite particle is preferably 99%-100%, and the thickness of the Si cladding layer shell is preferably 5-8 μm, and further preferably 6-8 μm.

[0047] In the present application, the purity of the composite particle is preferably 99.9999%.

[0048] The high-temperature-resistant SiC coating material according to the present application has a Si cladding layer shell as a binder phase, and a SiC base phase, wherein the SiC has a thermal expansion coefficient matching that of a high-strength alloy steel substrate, and the heat resistance can reach 1500-1600°C, thereby ensuring that the coating has excellent thermal cycle life on the high-strength alloy steel substrate.

[0049] The present application also provides a preparation method of the high-temperature-resistant SiC coating material according to the above technical solution, comprising the following steps:

[0050] SiH4 is introduced into a rotating fluidized bed, and SiH4 is cracked into H2 and Si atoms under a first temperature condition, and then SiC seed crystals are added;

[0051] Under a second temperature condition, the SiC seed crystals are blown up and gasified by H2 at a pressure of 0.1 MPa, Si atoms are deposited on the surface of the SiC particles to form a Si cladding layer shell, thereby obtaining a composite particle with a SiC inner core and a Si cladding layer shell.

[0052] The composite particle with a SiC inner core and a Si cladding layer shell is settled to the low end under the action of the rotating fluidized bed, and is collected after cooling, thereby obtaining the high-temperature-resistant SiC coating material.

[0053] In the present application, the first temperature is preferably 550-650 DEG C, and further preferably 550-600 DEG C; the second temperature is preferably 500-600 DEG C, and further preferably 550-600 DEG C.

[0054] In the present application, the rotation speed of the fluidized bed is preferably 500 rpm, the particle size of the SiC seed crystal is preferably 10-15 mu m, and the purity is preferably 99.9999%.

[0055] In the present application, the cracking time of SiH4 into H2 and Si atoms is preferably 30 mins.

[0056] In the present application, the deposition time of Si atoms on the surface of SiC particles is 1-2 hours.

[0057] Different deposition times of Si atoms on the surface of SiC particles in the present application will directly affect the thickness of the coating layer, and then affect the high-temperature stability of the subsequent SiC material, and the deposition time of 1-2 hours defined in the present application is more beneficial to the high-temperature reliability of the obtained SiC material.

[0058] The preparation process of the high-temperature-resistant SiC coating material is simple and efficient, the formed SiC ceramic wear-resistant coating is defect-free and has good adhesion with the substrate; at the same time, the Si atoms deposited on the surface of SiC particles form a coating layer, which can play a role as a binder phase in the thermal spraying process, and can generate SiO2 to prevent the sintering and densification of the SiC base phase in the high-temperature service environment, so that the coating always maintains excellent performance and meets the long-life use requirements.

[0059] The present application also provides a high-temperature-resistant SiC coating containing the high-temperature-resistant SiC coating material or the high-temperature-resistant SiC coating material prepared by the preparation method of the high-temperature-resistant SiC coating material.

[0060] In the present application, the high-temperature-resistant SiC coating is preferably prepared by ordinary plasma spraying or supersonic plasma thermal spraying technology.

[0061] The present application also provides a preparation method of the high-temperature-resistant SiC coating, comprising the following steps:

[0062] (1) drying the high-temperature-resistant SiC coating material;

[0063] (2) pretreating the substrate workpiece;

[0064] (3) using ordinary plasma spraying or supersonic plasma thermal spraying method to spray the high-temperature-resistant SiC coating material on the surface of the pretreated substrate, to obtain a substrate workpiece with a coating.

[0065] (4) the substrate workpiece with coating is nitrided in N2 furnace, so that mixed phases of SiC, Si and SiN are formed in the coating, and the high-temperature-resistant SiC coating is obtained;

[0066] The pretreatment comprises roughening, cleaning and drying;

[0067] The roughening is roughening by high-purity SiC;

[0068] The spraying condition is that the power is 28-35 kW, the cooling gas flow is 80-100 lpm, the spraying distance is 80-110 mm, the powder feeding rate is 30-40 g / min, and the coating thickness is 250-300 μm;

[0069] The nitriding temperature is 1100-1200 ℃, and the time is 200-300 mins.

[0070] In the application, the drying is preferably drying the high-temperature-resistant SiC coating material at 80 ℃ for 1 h; the roughening is preferably roughening by high-purity SiC, and further, the roughening is performed by a sand blasting machine.

[0071] In the application, the cleaning is preferably cleaning by alcohol or acetone.

[0072] In the application, the spraying is preferably vacuumizing the spraying cabin to 30 mbar, back-filling with argon to 50 mbar, and then spraying after reaching the spraying state.

[0073] In the application, the spraying condition is preferably that the power is 28-35 kW, the cooling gas flow is 80-100 lpm, the spraying distance is 80-110 mm, the powder feeding rate is 30-40 g / min, and the coating thickness is 250-300 μm; the cooling gas is preferably argon; further preferably, the power is 20-35 kW, the cooling gas flow is 80-90 lpm, the spraying distance is 90-110 mm, the powder feeding rate is 35-40 g / min, and the coating thickness is 250-270 μm, and the cooling gas is preferably argon.

[0074] In the application, the nitriding temperature is preferably 1100-1200 ℃, and the time is preferably 200-300 mins, and further preferably, the temperature is 1150-1200 ℃, and the time is 250-300 mins.

[0075] In the application, the proportion of each phase of SiC, Si and SiN in the high-temperature-resistant SiC coating is preferably 85%:5%:10% to 85%:4%:11%, wherein the SiC, Si and SiN exist in the form of mutual doping.

[0076] In the application, the coating porosity of the high-temperature-resistant SiC coating is 3% to 7%; the thickness of the high-temperature-resistant SiC coating is 250 to 350 microns; and the bonding property of the high-temperature-resistant SiC coating to the substrate is 23 to 38 MPa.

[0077] The Si in the high-temperature-resistant SiC coating material in the application replaces the conventional Co and Ni materials as a binder, and is prepared into a high-temperature-resistant high-purity coating through a common plasma spraying or supersonic plasma thermal spraying process. The highest use temperature can reach 1600 DEG C, which is 400 DEG C higher than the use temperature of the existing SiC high-temperature coating. The coating has good matching property to the substrate material, can fully exert the high-temperature-resistant advantage of ceramic materials, and has wide application in the new generation of semiconductor industry, aeroengines and gas turbines.

[0078] In the application, the required raw materials are all commercially available goods known to those skilled in the art, unless otherwise specified.

[0079] The technical solutions provided by the application will be described in detail below in combination with the embodiments, but they should not be understood as limiting the protection scope of the application.

[0080] Example 1

[0081] Preparation of the high-temperature-resistant SiC coating material

[0082] (1) SiC seed crystals with a particle size of 10 to 15 microns and a purity of 99.9999% are added into a fluidized bed with a rotation speed of 500 rpm;

[0083] (2) SiH4 gas is introduced, and SiH4 is cracked into H2 and Si atoms at a temperature of 550 DEG C for 30 mins;

[0084] (3) H2 with a pressure of 0.1 MPa is introduced at a temperature of 500 DEG C to make the SiC seed crystals boil and gasify, and Si atoms are deposited on the surface of the SiC seed crystal particles to form a coating shell. After 1 h of deposition, composite particles with SiC as the core and Si as the coating shell with a particle size of 30 to 45 microns are formed. The composite particles with SiC as the core and Si as the coating shell are settled to the low end under the action of the rotating fluidized bed, and are collected after cooling to obtain the high-temperature-resistant SiC coating material.

[0085] Example 2

[0086] Preparation of the high-temperature-resistant SiC coating material

[0087] (1) In a fluidized bed with a rotation speed of 500 rpm, SiC seed crystal with a particle size of 10-15 μm and a purity of 99.9999% is added;

[0088] (2) SiH4 gas is introduced, and SiH4 is cracked into H2 and Si atoms at a temperature of 650°C for 30 mins;

[0089] (3) H2 with a pressure of 0.1 MPa is introduced to boil and gasify the SiC seed crystal at a temperature of 600°C, and Si atoms are deposited on the surface of the SiC seed crystal particles to form a coating layer shell; after 2 h of deposition, SiC core-Si coating layer shell composite particles with a particle size of 40-50 μm are formed, and the SiC core-Si coating layer shell composite particles are settled to the low end under the action of the rotating fluidized bed, and are collected after cooling to obtain high-temperature-resistant SiC coating material.

[0090] Example 3

[0091] Preparation of high-temperature-resistant SiC coating

[0092] (1) The high-temperature-resistant SiC coating material prepared in Example 1 is dried at 80°C for 1 h;

[0093] (2) A sandblasting machine is used to polish and roughen the substrate workpiece using high-purity SiC particles, and alcohol is used for cleaning; after drying, the substrate workpiece is installed on the spraying workpiece and placed in a general plasma spraying cabin;

[0094] (3) The spraying cabin is vacuumed to 30 mbar, backfilled with argon to 50 mbar to reach the spraying state; at the same time, the spraying parameters are set as follows: power 30 kw, cooling argon gas, argon gas flow 100 lpm, spraying distance 90 mm, powder feeding rate 30 g / min, coating thickness 250 μm, backfilling argon gas when the temperature of the substrate workpiece is reduced to below 300°C, and cooling to below 100°C to take out the substrate workpiece coated with the coating;

[0095] (4) The substrate workpiece with the coating is placed in a N2 furnace for nitriding, and the temperature in the furnace is set to 1100°C, and the nitriding time is 3.5 h, so that a mixed phase of SiC, Si and SiN is formed in the coating, and the proportion of each phase in the high-temperature-resistant SiC coating is 85%:5%:10%, thereby obtaining a high-temperature-resistant SiC coating, the thickness of the high-temperature-resistant SiC coating is 250 μm, the porosity is 3.2%, the thermal shock resistance is 210 times in the 1600°C thermal shock experiment, and the adhesion to the substrate is 38 MPa.

[0096] Example 4

[0097] Preparation of high-temperature-resistant SiC coating

[0098] (1) the high-temperature-resistant SiC coating material prepared in Example 1 is dried at 80℃ for 1h;

[0099] (2) the substrate workpiece is polished and roughened by using a sand blasting machine and high-purity SiC particles, and is cleaned by using acetone, and is installed on the spraying workpiece after drying and is placed in a supersonic plasma spraying cabin;

[0100] (3) the spraying cabin is vacuumed to 30mbar, and is backfilled with argon to 50mbar to reach the spraying state; at the same time, the spraying parameters are set as follows: power 28kw, argon gas is selected for cooling, argon gas flow 80lpm, spraying distance 110mm, powder feeding rate 40g / min, coating thickness 300μm, argon gas is backfilled to cool to below 100℃ after the temperature of the substrate workpiece is reduced to below 300℃, and the substrate workpiece coated with the coating is taken out;

[0101] (4) the substrate workpiece with the coating is placed in a N2 furnace for nitriding, the temperature in the furnace is set to 1200℃, and the nitriding time is 5h, so that a mixed phase of SiC, Si and SiN is formed in the coating, the proportion of each phase in the high-temperature-resistant SiC coating is 85%:4%:11%, and the high-temperature-resistant SiC coating is obtained, the thickness of the high-temperature-resistant SiC coating is 300μm, the porosity is 6%, the thermal shock resistance number in the 1600℃ thermal shock experiment is 230 times, and the bonding strength with the substrate is 23MPa.

[0102] Based on the above, the high-temperature-resistant SiC obtained by the application has a thermal shock resistance number greater than 200 times in the 1600℃ thermal shock experiment, the bonding strength of the high-temperature-resistant SiC coating with the substrate is 23-38MPa, has excellent thermal stability at high temperature, and has excellent bonding strength with the substrate.

[0103] The above only describes the preferred embodiments of the application, and it should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the application, and these improvements and refinements should also be considered as the protection scope of the application.

Claims

1. A high temperature resistant SiC coating, characterized in that, The high-temperature-resistant SiC coating material comprises the following components in mass percentage: Si 8.0-15.0%, and the balance of SiC. The high-temperature-resistant SiC coating material comprises the following components in mass percentage: Si 8.0-15.0%, and the balance of SiC. The high-temperature-resistant SiC coating material is a composite particle of SiC and Si. The composite particle comprises a SiC inner core and a Si cladding layer shell. The composite particle has a particle size of 30-50 μm and a sphericity of 99-100%; the Si cladding layer shell has a thickness of 5-8 μm. The composite particle has a purity of 99.9999%. The preparation method of the high-temperature-resistant SiC coating material comprises the following steps: adding SiC seed crystals into a rotating fluidized bed, introducing SiH4, and making the SiH4 crack into H2 and Si atoms under a first temperature condition; under a second temperature condition, using H2 at a pressure of 0.1 MPa to make the SiC seed crystals boil and vaporize, and using 1-2 hours to make the Si atoms deposit on the surface of the SiC particles to form a Si cladding layer shell, thereby obtaining a composite particle with a SiC inner core and a Si cladding layer shell; under the action of the rotating fluidized bed, the composite particle with the SiC inner core and the Si cladding layer shell is settled to the low end and is collected after cooling, thereby obtaining the high-temperature-resistant SiC coating material; the first temperature is 550-650 ℃, and the second temperature is 500-600 ℃; the high-temperature-resistant SiC coating is prepared by using ordinary plasma spraying or supersonic plasma thermal spraying technology.

2. A method of producing the high-temperature-resistant SiC coating according to claim 1, characterized in that The method comprises the following steps: (1) drying the high-temperature-resistant SiC coating material; (2) pretreating a base workpiece; (3) using ordinary plasma spraying or supersonic plasma thermal spraying to spray the high-temperature-resistant SiC coating material on the surface of the pretreated base, thereby obtaining a base workpiece with a coating; (4) nitriding the base workpiece with the coating in an N2 furnace, so that a mixed phase of SiC, Si and SiN is formed in the coating, thereby obtaining the high-temperature-resistant SiC coating; the pretreatment comprises roughening, cleaning and drying; the roughening is performed by using high-purity SiC; the spraying conditions are as follows: power 28-35 kW, cooling gas flow rate 80-100 lpm, spraying distance 80-110 mm, powder feeding rate 30-40 g / min, and coating thickness 250-300 μm; the nitriding temperature is 1100-1200 ℃, and the time is 200-300 mins.

3. The method of claim 2, wherein the SiC coating is prepared by a method comprising: In the high-temperature-resistant SiC coating, the proportions of SiC, Si and SiN are 85%:5%:10% to 85%:4%:11%.

4. The method of claim 2, wherein the SiC coating is prepared by a method comprising: The porosity of the high-temperature-resistant SiC coating is 3%-7%, the thickness of the high-temperature-resistant SiC coating is 250-350 μm, and the bonding strength between the high-temperature-resistant SiC coating and the base is 23-38 MPa.

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