Iron-based amorphous alloy coating and preparation and surface layer densification treatment method thereof

Abstract

The invention belongs to the technical field of surface engineering, and particularly relates to an iron-based amorphous alloy coating and a preparation and surface layer densification treatment method thereof.The iron-based amorphous alloy coating is prepared from Fe-ETM-M, Fe-LTM-M or Fe-ETM-LTM-M, alloying elements and rare earth, the preparation method of the iron-based amorphous alloy coating comprises a hypersonic flame spraying method and a plasma spraying, flame spraying or cold spraying method, and the densification treatment method of the surface layer of the iron-based amorphous alloy coating comprises three steps of pre-burying, preheating and laser remelting. Iron-based amorphous alloy powder is pre-buried on an iron-based amorphous alloy coating prepared in a spraying mode for rapid remelting, crack propagation of the coating is inhibited by controlling stress release of the coating, the depth of laser surface layer rapid remelting reaches 20-50 microns, the amorphous retention rate is 75% or above, the surface layer porosity is smaller than or equal to 0.1%, the coating hardness reaches 1000 HV or above, and the surface layer thickness is 20-50 microns. A corrosion medium can be effectively prevented from permeating into a substrate from pores, the problems of expansion cracking and the like caused by interface corrosion of a coating substrate are solved, and the problem that tribological characteristics of the coating surface are changed by adding a hole sealing agent is solved.

Description

Technical Field:

[0001] The present invention belongs to the technical field of surface engineering, and particularly relates to an iron-based amorphous alloy coating and a preparation method and a surface densification treatment method thereof, which can regulate the microstructure of the iron-based amorphous alloy coating and broaden the application occasions of the iron-based amorphous alloy coating. Background Art:

[0002] The structural characteristics of amorphous alloys with short-range order and long-range disorder endow them with many excellent properties such as high strength, high hardness, high wear resistance, and high corrosion resistance. Among them, high corrosion resistance is one of the most concerned properties by researchers, mainly for the following two reasons: one is that it greatly reduces or even eliminates sensitive positions such as dislocations and grain boundaries that are prone to preferential corrosion; the other is that a large number of corrosion-resistant components are dissolved, which is easy to form a stable passivation film. At the same time, in the late stage of the initiation of corrosion pits, the metastable structural characteristics make the corrosion pits easy to repassivate and will not further develop deeper. Diamond-like materials exhibit excellent friction and wear properties due to their ultra-high hardness and self-lubricating ability. High wear resistance is also one of the most concerned properties by researchers. Amorphous alloys retain the disordered atomic structure of liquid melts, and there is more sufficient deformation space between atoms, endowing amorphous alloys with a high elastic modulus, making them have the characteristics of high strength and high hardness. Different from traditional metals, the surface of amorphous alloys exhibits liquid-like properties and has a self-lubricating effect, making many amorphous alloys exhibit a friction coefficient close to that of diamond-like materials (COFs < 0.2). However, due to the limitations of the formation size and intrinsic brittleness of bulk amorphous alloys, it is difficult to be used as a structural material. If it is used as a coating on the surface of components, the wear and corrosion resistance of amorphous alloys can be fully utilized.

[0003] Special service environments have relatively comprehensive and stringent requirements for the performance of the surface coatings of steel components. For example, for the protective coatings of underwater stressed parts of ships, in addition to requiring the coatings to have good anti-corrosion and wear resistance, it is also required that the coatings have a suitable match with the substrate. For example, when designing a composite layered structure of an amorphous alloy coating and a nickel-based alloy coating, although the introduction of a ductile nickel base layer can effectively improve the impact resistance of the coating, its large electrochemical property difference from the amorphous alloy makes the galvanic corrosion tendency of the composite coating serious. The corrosive medium penetrates through the pores to the matrix interface, corrosion occurs to form corrosion products, and the coating is cracked, overall reducing the corrosion performance of the coating. Another example is the composite coating prepared by adding ceramic particles with high melting points and brittleness. During the impact process, the fragmentation of the ceramic particles can absorb part of the impact energy, reduce crack propagation, and significantly improve the impact resistance of the coating. However, the addition of ceramic particles greatly increases the heterogeneous interfaces, and in a long-term corrosion environment, the heterogeneous interfaces promote the penetration of the corrosive medium into the coating.

[0004] High hardness, which is an advantage of iron-based amorphous alloys in terms of wear resistance, poses a great disadvantage in coating preparation. Iron-based amorphous materials have the hardness and brittleness of glassy substances and have extremely high requirements for the processes of preparing high-quality coatings. During spraying processes such as supersonic flame spraying, plasma spraying, explosion spraying, and cold spraying, it is extremely difficult for amorphous powder particles to deform: the deformed particles cannot fully occupy the macroscopic pores in the space, and the bonding between particle interfaces is not tight enough, resulting in a high porosity of the coating. Corrosion media can easily penetrate through the defects to reach the substrate interface, leading to substrate corrosion, etc. For titanium alloy and stainless steel substrates, the self-corrosion potential of iron-based amorphous alloys is comparable to theirs. Even if the corrosion media penetrate into the substrate, it will not cause serious negative impacts, and the covering of the coating greatly reduces the probability of defects in stainless steel, etc. coming into contact with the corrosion media, enabling metal materials with corrosion resistance characteristics such as titanium alloy and stainless steel to also have good wear resistance, thereby achieving the purpose of comprehensively improving the anti-corrosion and wear resistance performance. However, limited by cost, most current structures use steel. The self-corrosion potential of steel is between about -600 and -700 mV, which has a large difference from the self-corrosion potential (-0.2 - 0.2 V) of the iron-based amorphous alloy coating. When there are penetrating pores in the coating, the corrosion media penetrate to the substrate interface, and the potential difference between the two accelerates the corrosion behavior of the substrate. At the same time, the interior of the pores is continuously acidified, making the corrosion more serious. However, steel not only needs to be wear-resistant but also corrosion-resistant in the corrosion media. The existence of pores shortens the service life of the substrate and brings great potential safety hazards. Currently, it is almost impossible to prepare a completely dense amorphous coating. Only organic or inorganic sealing materials can be used to seal the pores, allowing the sealing substances to penetrate into the pores and block the penetration channels of the corrosion media, delaying the time for the corrosion media to penetrate through the pores to the substrate and extending the anti-corrosion life of the coating.

[0005] An anti-wear and corrosion-resistant iron-based amorphous coating sealing agent disclosed in Chinese Patent 202011072118.7 is composed of the following components in parts by weight: 100 parts of epoxy resin AB glue; 1 - 5 parts of γ-aminopropyltriethoxysilane; 0.1 - 1 part of cetylamine; 5 - 20 parts of iron-based amorphous alloy powder. The sealing method includes: Step 1: Pretreat the surface of the iron-based amorphous coating; Step 2: Coat the anti-wear and corrosion-resistant iron-based amorphous coating sealing agent on the surface of the iron-based amorphous coating; Step 3: Under the cyclic air pressure of "vacuum pumping - pressure release - vacuum pumping", perform ultrasonic oscillation on the iron-based amorphous coating coated with the anti-wear and corrosion-resistant iron-based amorphous coating sealing agent for 90 - 150 minutes;

[0006] Step 4: Cure the anti-wear and corrosion-resistant iron-based amorphous coating sealing agent by drying at a constant temperature of 60°C for 3 hours. It can achieve the sealing effect of wear resistance and corrosion resistance.

[0007] A sealing agent for preparing Fe-based amorphous coatings by HVOF, disclosed in Chinese Patent No. 201710649533.6, is prepared from tetrafluoroethylene, absolute ethanol, nano-Al2O3, mica filler, dispersant and film-forming aid; the preparation method steps are as follows: (1) Mix 50 parts of polytetrafluoroethylene with absolute ethanol at a volume ratio of 1:2, then add 25 parts of nano-Al2O3 and disperse evenly by ultrasonic; (2) Add 10 parts of mica filler, 5 parts of dispersant and 5 parts of film-forming aid to the ultrasonically dispersed mixture, and then add an appropriate amount of absolute ethanol solvent to adjust the viscosity; (3) Place the materials from the previous step together in a high-speed disperser, disperse evenly, filter, and seal and let stand to prepare the required sealing agent. It can effectively solve the problems of porosity and crystallization.

[0008] A pore sealing treatment method for improving the corrosion resistance of amorphous alloy coatings, disclosed in Chinese Patent No. 202211628583.3, cures a silicate conversion film on the surface of the sprayed coating to seal the pores on the coating surface; before the sealing treatment, the amorphous coating is first degreased with acetone, then washed with deionized water, then ultrasonically cleaned in ethanol, and finally the sealing treatment of the amorphous alloy coating is carried out to reduce or eliminate the pore defects on the coating surface, thereby significantly improving the corrosion resistance of the amorphous alloy coating.

[0009] A preparation method of a fully amorphous crack-free Fe-based amorphous coating by ultra-high-speed laser cladding, disclosed in Chinese Patent No. 202410003544.7, includes the following steps: S1. Perform surface treatment on the disk-shaped workpiece to be clad; S2. Perform preheating treatment on the workpiece to be clad, clamp the preheated workpiece to be clad with a chuck and place it flat on a rotating carrier; S3. Add alloy powder into the cladding device and adjust the powder feeding speed, carrier gas flow rate and protective gas flow rate of the cladding device; S4. Adjust the distance between the cladding head and the workpiece to be clad, the laser focus and the powder flow focus to ensure that the laser focus coincides with the powder focus, and the defocus amount range during the ultra-high-speed laser cladding process is always 0-10 mm above the surface of the workpiece to be clad; S5. Set the moving speed of the cladding head; S6. The rotating carrier drives the workpiece to be clad to rotate, and start laser cladding from the outside to the inside to form a fully amorphous crack-free Fe-based amorphous coating by ultra-high-speed laser cladding on the surface of the workpiece to be clad. The prepared Fe-based amorphous alloy coating has no cracks.

[0010] The scientific and technological literature "Sealing and Reprocessing of Iron-based Amorphous Coatings and Evaluation of Their Environmental Adaptability" reported the effects of sealing treatment on the anti-corrosion and wear-resistant properties of coatings. During the spraying preparation process of iron-based amorphous coatings, due to limitations of many factors such as technology, different types of pore defects will occur, which greatly reduces their service life and causes huge losses in engineering. Aiming at the inherent pore defects of iron-based amorphous coatings serving in the marine atmospheric environment, a sealing reprocessing technology was developed to effectively seal the coating pores without changing its surface state. Based on the research of sealing corrosion inhibitors, the corrosion behavior and sealing mechanism of the coatings before and after sealing treatment were studied. Finally, the differences in corrosion resistance before and after sealing reprocessing were actually verified through four artificial accelerated corrosion tests, and their environmental adaptability was evaluated. The research shows that for the corrosion inhibitor of the iron-based amorphous coating substrate L921A steel, the anodic action coefficient is 0.11, the cathodic action coefficient is 0.13, and the ratio of the anodic and cathodic action coefficients is 0.85, which proves that the corrosion inhibitor is an anodic type corrosion inhibitor, and the corrosion inhibition rate can reach more than 96%; in an environment of 25°C, the concentration of the corrosion inhibitor is increased by 4 times, and 20% ethanol is added and the coating is statically soaked for 6 h and then naturally dried to effectively seal the coating pores. After sealing, the polarization resistance value of the coating increased by 4.7 times. The sealing corrosion inhibitor for iron-based amorphous coatings can effectively inhibit the anodic corrosion process of the coating. From the corrosion law of the coating system before and after sealing reprocessing, it is found that the corrosion reaction mainly comes from the substrate. Sealing reprocessing can effectively reduce the corrosion weight loss of the coating system and macroscopically improve the corrosion resistance of the coating system. At the same time, it shows that the sealing reprocessing will not affect the mechanical properties of the coating through the supersonic flame erosion test. However, through the sealing treatment, although the corrosion phenomenon is greatly inhibited, the friction coefficient on the coating surface is reduced to about 0.13, completely changing its tribological behavior.

[0011] To sum up, the high wear-resistant and corrosion-resistant comprehensive performance of amorphous alloy coatings requires the coating to have a dense organizational structure and to be electrochemically matched with the substrate. However, at present, only reliable high corrosion resistance can be achieved by sealing treatment. The sealing treatment will cause changes in the friction coefficient of the coating and affect the stable operation of the mechanical structure. At the same time, the self-corrosion potential of the iron-based amorphous coating is more positive than that of the steel substrate, and there is a greater risk of galvanic corrosion. When using an iron-based amorphous coating to protect the substrate, the substrate needs to be completely coated, which limits the application scenarios. Therefore, it is of great significance to develop and design an iron-based amorphous coating with electrochemically matched performance and to completely densify it for broadening its application environment. Summary of the Invention:

[0012] The object of the present invention is to overcome the drawbacks of the prior art, and develop and design an iron-based amorphous alloy coating and its preparation and surface densification treatment method, by eliminating the penetrating pores of the coating, so that it can carry out effective corrosion protection under non-closed conditions, and solve the problem of the coating accelerating the corrosion of the substrate caused by the pores.

[0013] To achieve the above object, the raw materials of the iron-based amorphous alloy coating involved in the present invention include Fe-ETM-M, Fe-LTM-M or Fe-ETM-LTM-M, as well as alloying elements, rare earths and ceramics;

[0014] Among them, the alloying elements include early transition metal elements ETM (such as Y, Nb, Cr, Mo, W, etc.), late transition metal elements LTM (such as Mn, Co, Ni, etc.), and metalloid elements M (such as B, P, Si, C, etc.);

[0015] The mass fraction of rare earth is 0.2-2.0%, including Re x O y (such as La 2 O 3 , Y 3 O 2 and CeO 2 ), added in the form of powder, and subjected to vibrating sieve mixing during addition, which can improve the anti-crack development performance of the coating during the cladding process;

[0016] The addition amount of ceramics is 5-20wt%, including WC, Al 2 O 3 , ZrO 2 , Cr 2 C 3 , added in the form of particles, with a particle size of 5-75μm, which can improve the hardness of the coating after addition.

[0017] The preparation method of the iron-based amorphous alloy coating involved in the present invention includes the supersonic flame spraying method and other spraying methods such as plasma spraying, flame spraying, and cold spraying; before spraying, the surface of the substrate is cleaned, sandblasted, and shot peened, etc., so that the cleanliness level reaches above Sa2.5.

[0018] The process of preparing an iron-based amorphous alloy coating by supersonic flame spraying is to heat and melt the amorphous alloy powder with a particle size of 18 - 45 μm and then spray it onto the surface of the substrate or component; the process parameters are as follows: the fuel gas is propane, the combustion-supporting agent is compressed air, hydrogen and nitrogen are used to improve the process flexibility, the compressed air pressure is 80 - 85 psi, the gas pressure is 76 - 81 psi, the propane flow rate is 120 - 130 SLPM, the hydrogen flow rate is 25 - 28 SLPM, the nitrogen flow rate is 25 - 28 SLPM, the powder feeding rate is 20 - 40 g / min, and the spraying distance is 200 - 350 mm.

[0019] The process parameters of preparing an iron-based amorphous alloy coating by cold spraying are as follows: the nozzle expansion ratio is 6 - 12, the nozzle throat diameter is 2 - 3 mm, the downstream of the nozzle is 350 - 500 mm, the distance from the nozzle outlet to the substrate or component is 10 - 50 mm, the spraying pressure is 3.5 - 7 MPa, the spraying temperature is 600 - 1100 °C, the powder feeding rate is 1 - 5.0 g / s, the spraying angle is 90 ± 15 °, the nozzle transverse speed is 10 - 50 mm / s, and the powder particle size is 10 - 45 μm.

[0020] The surface densification treatment method of the iron-based amorphous alloy coating involved in the present invention controls stress by the co-deposition of the coating and the embedded powder, and is applicable to various metal substrates with a thickness ≥ 0.5 mm, including but not limited to carbon steel, stainless steel, copper alloy, titanium alloy, etc.; the specific process includes three steps: embedding, preheating, and laser remelting:

[0021] First, embed iron-based amorphous alloy powder with a loose packing thickness of 15 - 35 μm on the coating surface, and use epoxy putty with a volume ratio of 5 - 10% as the binder.

[0022] Then, preheat the embedded iron-based amorphous alloy powder, and the preheating temperature is 80 - 150 °C.

[0023] Finally, use rapid laser remelting to process the embedded iron-based amorphous alloy powder. The maximum power of the laser is 30 - 200 w, the repetition frequency of the laser ≤ 25 kHz, the scanning speed of the laser is 20 - 50 mm / s, the frequency is 5 KHz, the cladding power ratio is 20 - 60%, the laser spot is 2 - 5 mm, and the laser overlapping rate is 20 - 45%.

[0024] Compared with the prior art, in the iron-based amorphous alloy coating prepared by spraying, iron-based amorphous alloy powder is pre-embedded and rapidly remelted. By controlling the stress release of the coating, the crack propagation of the coating is inhibited, ensuring that the surface of the coating is dense and crack-free after melting, cooling and solidification, completely eliminating the penetrating pores in the coating. The depth of rapid surface remelting by laser reaches 20-50μm, the amorphous retention rate is above 75%, the surface porosity is ≤0.1%, and the hardness of the coating reaches above 1000HV, which can effectively prevent corrosive media from penetrating into the substrate through the pores, solve problems such as swelling and cracking caused by corrosion at the coating-substrate interface, and improve the problem of changing the tribological characteristics of the coating surface by adding a sealing agent. Description of the Drawings:

[0025] Figure 1 It is a schematic diagram of the process of laser remelting related to the present invention.

[0026] Figure 2 It is a cross-sectional micrograph of an iron-based amorphous alloy coating prepared by the supersonic flame spraying method related to the present invention.

[0027] Figure 3 It is a cross-sectional micrograph of an iron-based amorphous alloy coating prepared by the supersonic flame spraying method after laser remelting related to the present invention.

[0028] Figure 4 It is an XRD spectrum of an iron-based amorphous alloy coating prepared by the supersonic flame spraying method after laser remelting related to the present invention.

[0029] Figure 5 It is a hardness distribution diagram of an iron-based amorphous alloy coating prepared by the supersonic flame spraying method after laser remelting related to the present invention.

[0030] Figure 6 It is a potentiodynamic polarization curve diagram of an iron-based amorphous alloy coating prepared by the supersonic flame spraying method after laser remelting related to the present invention. Detailed Embodiments:

[0031] The present invention will be further described below through embodiments in combination with the drawings.

[0032] Embodiment 1:

[0033] The iron-based amorphous alloy coating in this embodiment uses ordinary Q235 carbon steel with a thickness greater than 5mm as the substrate, and uses iron-based amorphous alloy Fe 42 Co 25 Cr 15 Mo 12 C 3 B 2 Y 1 +1.2wt% CeO 2 as the raw material;

[0034] The iron-based amorphous alloy coating is prepared by the cold spraying method. The raw materials are added in the form of powder, and vibration sieving and mixing are carried out during the addition. The process parameters are as follows: the nozzle expansion ratio is 9, the nozzle throat diameter is 2 mm, the downstream of the nozzle is 350 mm, the distance from the nozzle outlet to the substrate is 25 mm, the spraying pressure is 5.5 MPa, the spraying temperature is 750 °C, the powder feeding rate is 1 g / s, the spraying angle is 90°, the nozzle transverse speed is 50 mm / s, and the powder particle size is 10 - 45 μm.

[0035] The process of densifying the surface of the iron-based amorphous alloy coating is as follows:

[0036] First, stress control is carried out by the co-fusion deposition of the coating and the pre-buried powder. Iron-based amorphous alloy powder with a loose packing thickness of 35 μm is pre-buried on the coating surface, and epoxy putty with a volume ratio of 5% is used as the binder to increase the deformation freedom during the solidification of the coating;

[0037] Then, the pre-buried iron-based amorphous alloy powder and the substrate are pre-heated to 120 °C;

[0038] Finally, the iron-based amorphous alloy coating is treated by rapid laser remelting, as Figure 1 shown. The maximum power of the laser is 50 w, the laser repetition frequency ≤ 25 kHz, the laser scanning speed is 50 mm / s, the frequency is 5 KHz, the cladding power ratio is 50%, the laser spot is 3 mm, and the laser overlapping rate is 30%;

[0039] After the laser remelting treatment, according to the apparent cladding effect, if necessary, local re-burial of iron-based amorphous alloy powder is carried out, and the pre-heating and laser remelting processes are repeated with the process parameters unchanged.

[0040] Cutting characterization is carried out on the iron-based amorphous alloy coating with surface densification treatment:

[0041] The cross-sectional microstructure of the iron-based amorphous alloy coating prepared by the cold spraying method is as Figure 2 shown. There are very many particle interfaces and pores on the cross-section, and the corrosive medium can penetrate from the penetrative pores or interfaces to the substrate, thus causing accelerated corrosion of the substrate;

[0042] The cross-sectional microstructure of the iron-based amorphous alloy coating prepared by the cold spraying method after laser remelting is as Figure 3 shown. There is a very dense remelting layer about 30 - 50 μm thick on the surface layer, with almost no visible defects under the microscope and the porosity is less than 0.1%;

[0043] The XRD spectrum of the iron-based amorphous alloy coating prepared by the cold spraying method after laser remelting is as Figure 4As shown, as the laser power increases, the phase peaks on the XRD spectrum become more obvious, indicating that a higher power forms a molten pool with a higher temperature. The crystallization rate at 50% of the laser power is below 22.6%, and the amorphous content in the coating is still above 77.4%, which can maintain good corrosion resistance and wear resistance.

[0044] The hardness distribution of the iron-based amorphous alloy coating prepared by the cold spraying method after laser remelting is as Figure 5 shown, and the potentiodynamic polarization curve is as Figure 6 shown. The hardness has increased, and the corrosion resistance is below 1×10 -6 A / cm 2 , indicating that it has good anti-wear and corrosion resistance.

[0045] Abstract of the specification:

[0046] The present invention belongs to the field of surface engineering technology, and specifically relates to an iron-based amorphous alloy coating and its preparation and surface densification treatment method. After preparing the iron-based amorphous alloy coating by spraying, the iron-based amorphous alloy coating is rapidly remelted to ensure that the surface is melted and solidified without cracks, and the penetrating pores in the coating are completely eliminated. The depth of laser rapid remelting can reach 20 - 50 μm, the surface porosity ≤ 0.1%, and the coating hardness can reach above 1000 HV, which can effectively prevent corrosive media from penetrating into the substrate through the pores and prevent problems such as swelling and cracking caused by interfacial corrosion, and improve the problem of changing the surface friction characteristics of the coating by adding a sealing agent. Compared with most current laser cladding processes, the heat input to the substrate is extremely low, only 1 / 10 of the power of ordinary laser cladding, and the thermal impact on the substrate is extremely small, and the substrate hardly deforms, which can solve the comprehensive corrosion-wear damage problem of heavy-duty friction components in the marine environment and has good application prospects.

Claims

1. An iron-based amorphous alloy coating, characterized in that: The raw materials include Fe-ETM-M, Fe-LTM-M or Fe-ETM-LTM-M and alloying elements and rare earths.

2. The iron-based amorphous alloy coating according to claim 1, characterized in that: Raw materials also include ceramics.

3. An iron-based amorphous alloy coating according to claim 1 or 2, characterized in that: Alloying elements include early transition elements ETM, late transition elements LTM, and metalloid elements M; the mass fraction of rare earth is 0.2-2.0%, including Re x O y , added in powder form, vibrating and sieving to improve the coating's resistance to crack development during the cladding process.

4. The iron-based amorphous alloy coating according to claim 2, characterized in that: The ceramics are added in an amount of 5-20wt%, including WC, Al2O3, ZrO2, and Cr2C3, in the form of particles with a particle size of 5-75μm to improve the hardness of the coating.

5. A method for preparing an iron-based amorphous alloy coating, characterized in that: These include supersonic flame spraying methods as well as plasma spraying, flame spraying or cold spraying methods.

6. The method for preparing an iron-based amorphous alloy coating according to claim 5, characterized in that: Before spraying, the substrate surface is cleaned, sandblasted or shot blasted to ensure that the cleanliness level reaches Sa2.5 or above.

7. The method for preparing an iron-based amorphous alloy coating according to claim 5 or 6, characterized in that: When preparing by the supersonic flame spraying method, the amorphous alloy powder with a particle size of 18-45μm is heated and melted and then sprayed onto the surface of the substrate or component; the process parameters are as follows: the fuel gas is propane, the combustion aid is compressed air, hydrogen and nitrogen are used to improve the flexibility of the process, the compressed air pressure is 80-85psi, the fuel gas pressure is 76-81psi, the propane flow rate is 120-130SLPM, the hydrogen flow rate is 25-28SLPM, the nitrogen flow rate is 25-28SLPM, the powder feeding rate is 20-40g / min, and the spraying distance is 200-350mm.

8. The method for preparing an iron-based amorphous alloy coating according to claim 5 or 6, characterized in that: The process parameters of the cold spraying method are as follows: nozzle expansion rate is 6-12, nozzle throat diameter is 2-3mm, nozzle downstream is 350-500mm, the distance from the nozzle outlet to the substrate or component is 10-50mm, the spraying pressure is 3.5-7MPa, the spraying temperature is 600-1100℃, the powder feeding rate is 1-5.0g / s, the spraying angle is 90±15°, the nozzle lateral speed is 10-50mm / s, and the powder particle size is 10-45μm.

9. A method for densifying the surface of an iron-based amorphous alloy coating, characterized in that: The process includes three steps: pre-embedding, pre-heating and laser remelting: First, iron-based amorphous alloy powder is embedded in the coating surface; Then, the embedded iron-based amorphous alloy powder is preheated to 80-150°C; Finally, the embedded iron-based amorphous alloy powder is processed by laser remelting.

10. The method for surface densification of an iron-based amorphous alloy coating according to claim 9, characterized in that: Stress control is achieved by co-deposition of coating and embedded powder; Applicable to metal substrates with a thickness of ≥0.5mm, including carbon steel, stainless steel, copper alloy and titanium alloy; The pre-embedded loose thickness of the iron-based amorphous alloy powder is 15-35 μm, and the epoxy glue with a volume proportion of 5-10% is used as a binder; The maximum power of the laser is 30-200w, the repetition frequency of the laser is ≤25kHz, the scanning speed of the laser is 20-50mm / s, the frequency is 5KHz, the cladding power ratio is 20-60%, the laser spot is 2-5mm, and the laser overlap rate is 20-45%.

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