Corrosion-resistant metal composite coating, composite coating as well as preparation method and application of corrosion-resistant metal composite coating

Abstract

The invention discloses a corrosion-resistant metal composite coating, a composite coating as well as a preparation method and application of the corrosion-resistant metal composite coating. The coating is prepared from La2O3 powder and Ni-based alloy containing Mo and Cr, wherein the weight ratio of the Mo element to the La element is 15: (0.5-3). The coating provided by the invention has good machinability and corrosion resistance, and especially has excellent performance in a high-temperature chlorine-containing atmosphere corrosion environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of coatings, and particularly relates to a corrosion-resistant metal composite coating, a composite coating, and a preparation method and application thereof. Background Art

[0002] With the increasing urban population, a large amount of urban garbage and industrial waste need to be properly disposed of. Waste incineration power generation technology is currently the best way to deal with solid waste. As one of the key equipment in the waste incineration system, most incinerators currently use steel materials such as 316 stainless steel as the furnace body material. However, in the harsh working conditions of erosion by chlorine-containing corrosive gases at high temperatures in waste incineration, the corrosion rate is severely accelerated. Therefore, surface coating technology is used to increase corrosion resistance.

[0003] The patent with application number 202010879933.8 discloses an oxide dispersion strengthened nickel-based alloy. This alloy is obtained by laser cladding forming of nickel-based alloy powder coated with nano-oxides. Although this invention improves the work hardening and powder morphology during ball milling and mixing of powders, its overly fine powder affects the powder fluidity and is not suitable for the coaxial powder feeding laser cladding process method.

[0004] The patent with application number CN202310140292.8 discloses a nickel-based alloy powder for protecting waste incineration boilers and a coating preparation method. By weight percentage, the nickel-based alloy powder includes: Cr 21 - 23%; Fe 0.5 - 1.0%; Mo 8.5 - 9.5%; Nb 3.5 - 3.8%; Al 0.2 - 0.3%; Ti 0.2 - 0.3%; Mn 0.1 - 0.2%; Si 0.1 - 0.3%; C 0.01 - 0.04%; B 0.008 - 0.015%; Zr 0.01 - 0.02%; P ≤ 0.006%; S ≤ 0.002%; O ≤ 0.08%; N ≤ 0.06%; the balance is Ni. The nickel-based alloy powder has good hardness and impact resistance, and also has good corrosion resistance at high temperatures.

[0005] The patent with the application number 201611225047.3 discloses a corrosion-resistant, oxidation-resistant, low-wear and abrasion-resistant ball and its preparation method. The wear-resistant ball includes a cladding layer and a wear-resistant ball matrix, and the wear-resistant ball matrix includes the following components: C, Si, Mn, Cr, Ni, Cu, Al, Ca, B, Ti, Zr, Nb, Mo, V, La, P, Fe and inevitable impurities. During the preparation process, plasma cladding technology and laser cladding technology are used to coat two cladding layers on the surface of the wear-resistant ball matrix, and the corrosion-resistant, oxidation-resistant, low-wear and abrasion-resistant ball is obtained by combining cold treatment and low-temperature tempering technology. A corrosion-resistant, oxidation-resistant, low-wear and abrasion-resistant ball proposed by the present invention has the advantages of high strength, high hardness, good oxidation resistance and corrosion resistance, low wear and long service life.

[0006] However, during the laser cladding process of the above alloy powder and traditional Ni-Cr-Mo series alloys, elements in the matrix will diffuse into the coating, resulting in coating dilution, and impurity elements such as S, Si, and P will increase the inclusion content in the coating, leading to a decrease in the corrosion resistance of the coating. Therefore, it is necessary to improve the existing nickel-based alloy coating materials to improve the processability, high-temperature resistance and high-temperature corrosion resistance (especially high-temperature chlorine-containing atmosphere corrosion resistance) of the coating. Summary of the Invention

[0007] Aiming at the problems existing in the prior art, such as poor processability and corrosion resistance in nickel-based alloy coatings, especially poor chlorine corrosion resistance. The present invention designs and provides a corrosion-resistant metal composite coating, a composite coating, and their preparation methods and applications. The coating of the present invention has good processability and corrosion resistance, and especially performs excellently in a high-temperature chlorine-containing atmosphere corrosion environment.

[0008] On the one hand, the present invention provides a corrosion-resistant metal composite coating, which includes La2O3 powder and a Ni-based alloy containing Mo and Cr; among them, the weight ratio of Mo element to La element is 15:0.5 - 3.

[0009] Preferably, the composite coating forms a Cr2O3-La4MoO9 protective layer at 600 - 1000 °C.

[0010] Preferably, by weight percentage, the corrosion-resistant metal composite coating contains 0.1 - 1.5% by weight of La2O3 and 98.5 - 99.9% by weight of a Ni-based alloy containing Mo and Cr.

[0011] Preferably, by weight percentage, the corrosion-resistant metal composite coating contains 0.5 - 1.5% by weight of La2O3 and 98.5 - 99.5% by weight of a Ni-based alloy containing Mo and Cr.

[0012] Preferably, the Ni-based alloy containing Mo and Cr is selected from one or more of Hastelloy C22, Hastelloy C276, Hastelloy C2000 alloy, Inconel 625, Inconel 718 alloy, Alloy 31, and Alloy 59 alloy.

[0013] Preferably, the average particle size of the powder of the Ni-based alloy containing Mo and Cr is 80 - 100 μm.

[0014] Preferably, the average particle size of the La2O3 powder is 5 - 10 μm.

[0015] On the other hand, the present invention provides a corrosion-resistant metal composite coating, which is obtained by laser cladding the above-mentioned corrosion-resistant metal composite coating on a substrate.

[0016] Preferably, the thickness of the composite coating is 0.3 mm - 1 mm.

[0017] Preferably, the temperature that the corrosion-resistant metal composite coating can withstand is 600 - 1000 °C.

[0018] Preferably, the concentration of HCl that the corrosion-resistant metal composite coating can withstand is 1 - 10 vol%.

[0019] On yet another aspect, the present invention provides a preparation method of the above-mentioned corrosion-resistant metal composite coating, including the following steps:

[0020] Step 1: Mix the Ni-based alloy containing Mo and Cr with the La2O3 powder to obtain a mixed powder;

[0021] Step 2: Laser clad the mixed powder obtained in Step 1 on a substrate.

[0022] Preferably, the conditions of the laser cladding include: the laser power is 1600 - 2000 W, the cladding speed is 2 - 4 mm / s, and the overlapping rate is 30 - 60%.

[0023] Preferably, the laser cladding adopts a coaxial powder feeding method or a powder spreading method.

[0024] More preferably, the powder feeding speed is 20 - 30 g / min

[0025] Preferably, an inert gas is continuously introduced during the laser cladding.

[0026] More preferably, the flow rate of the inert gas is 9 - 15 L / min.

[0027] Preferably, the conditions of the mixing include: mixing in a vacuum or inert atmosphere ball mill for 2 - 5 h.

[0028] In another aspect of the present invention, there is provided the use of the above-mentioned corrosion-resistant metal composite coating and / or the above-mentioned corrosion-resistant metal composite coating in the field of waste incineration, especially in waste incinerators.

[0029] Advantages of the present invention

[0030] (1) The high-temperature chlorine corrosion-resistant La2O3 / nickel-based composite coating of the present invention uses a nickel-based alloy mainly composed of Ni, Cr, and Mo as the matrix. Compared with the Mo element, a specific content of the oxide La2O3 is compounded. The La2O3 particles are dispersed at the grain boundaries of the coating. In a high-temperature corrosion environment, La2O3 reacts with MoO2 to form the La4MoO9 phase, which is distributed in the oxide layer and has excellent thermal stability. A Cr2O3-La4MoO9 protective layer is formed in the oxide layer on the coating surface, thereby significantly improving the high-temperature corrosion resistance (especially the corrosion resistance to high-temperature chlorine-containing atmospheres) of the La2O3 / nickel-based composite coating of the present invention.

[0031] (2) In the composite coating of the present invention, Ni itself has good corrosion resistance, the vapor pressure of nickel chloride is low, the lattice disorder of the nickel-based is low, Cr helps to form a passivation film, and Mo is beneficial to improving the pitting corrosion and crevice corrosion resistance of the material. However, by adding an appropriate amount of La2O3, the solidification range and solidification time of the coating are shortened, which is beneficial to reducing the dilution of the substrate to the cladding material and refining the grain structure of the coating. And during the cladding process, La2O3 forms high-melting-point compounds with impurity elements such as S, Si, and P. These compounds will float on the upper layer in the liquid phase before solidification and finally stay on the surface, thereby reducing the inclusion content. Therefore, the coating prepared from the composite coating obtained by compounding La2O3 with a Ni-based alloy containing Mo and Cr has better corrosion resistance and can be widely used in extreme working conditions.

[0032] (3) There is a problem that the existing coaxial powder feeding laser cladding process method is not applicable to the composite coating, while the corrosion-resistant metal composite coating of the present invention is applicable to the laser cladding process method and has excellent processability.

[0033] (4) In the present invention, the composite coating prepared by the laser cladding method using the composite coating of the present invention purifies the impurity elements inside the coating and reduces inclusions. Description of the drawings

[0034] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. The following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0035] Figure 1 Schematic diagram of the preparation process of the corrosion-resistant metal composite coating in an embodiment of the present invention.

[0036] Figure 2 Cross-sectional SEM morphology and EDS spectrum of Example 1 of the present invention after 60 h of high-temperature chlorine corrosion test at 900°C.

[0037] Figure 3 Cross-sectional SEM morphology and EDS spectrum of Comparative Example 1 of the present invention after 60 h of high-temperature chlorine corrosion test at 900°C.

[0038] Figure 4 XRD of Example 2 and Comparative Example 1 of the present invention after 60 h of high-temperature chlorine corrosion test at 900°C.

[0039] Figure 5 Impedance diagram of electrochemical tests of Example 3 and Comparative Example 1 of the present invention.

[0040] Figure 6 Polarization curve of electrochemical tests of Example 3 and Comparative Example 1 of the present invention.

[0041] Figure 7 EDS diagram of Example 3 and Comparative Example 1 of the present invention.

[0042] Figure 8 Corrosion kinetics curve of Example 5 and Comparative Example 1 of the present invention after 60 h of high-temperature chlorine corrosion test at 900°C.

[0043] Figure 9 Corrosion kinetics curve of Example 13 and Comparative Example 1 of the present invention after 60 h of high-temperature chlorine corrosion test at 900°C.

[0044] Figure 10 Corrosion kinetics curve of Example 14 and Comparative Example 1 of the present invention after 60 h of high-temperature chlorine corrosion test at 900°C.

[0045] Figure 11 Cross-sectional SEM morphology and EDS of Comparative Example 3 of the present invention after 60 h of high-temperature chlorine corrosion test at 900°C.

[0046] Figure 12 Corrosion kinetics curve of Comparative Example 4 and Example 2 of the present invention after 60 h of high-temperature chlorine corrosion test at 900°C. Specific embodiments

[0047] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work belong to the protection scope of the present invention.

[0048] In the first aspect of the present invention, a corrosion-resistant metal composite coating is provided. The coating includes La2O3 powder and a Ni-based alloy containing Mo and Cr. Among them, the weight ratio of Mo element to La element is 15:0.5 - 3. In the present invention, when the weight ratio of Mo element to La element is 15:0.5 - 3, in a high-temperature chlorine corrosion environment, La2O3 reacts with MoO2 to form the La4MoO9 phase. This phase is distributed in the oxide layer and has excellent thermal stability. A Cr2O3-La4MoO9 protective layer is formed in the oxide layer on the coating surface. Therefore, the corrosion resistance of the composite coating of the present invention, especially the chlorine corrosion resistance, is excellent and can be used in working conditions such as high-temperature chlorine-containing atmospheres in waste incinerators to improve the corrosion resistance of waste incinerators and extend their service life.

[0049] According to some embodiments of the present invention, the Cr2O3-La4MoO9 protective layer is formed in the composite coating at 600 - 1000 °C. From the appearance presented in the SEM image (such as Figure 2 ) and the presence of Cr2O3 and La4MoO9 in the high-temperature XRD products, it can be seen that the composite coating of the present invention can form a Cr2O3-La4MoO9 protective layer at high temperatures, and the corrosion kinetics curve and other data can illustrate that this protective layer can improve the high-temperature chlorine corrosion resistance of the coating.

[0050] According to some embodiments of the present invention, by weight percentage, the corrosion-resistant metal composite coating contains 0.1 - 1.5 wt% of La2O3 and 98.5 - 99.9 wt% of a Ni-based alloy containing Mo and Cr. Preferably, by weight percentage, the corrosion-resistant metal composite coating contains 0.5 - 1.5 wt% of La2O3 and 98.5 - 99.5 wt% of a Ni-based alloy containing Mo and Cr. When the La2O3 content defined in the present invention is adopted, it can shorten the solidification range and solidification time of the composite coating, which is beneficial to reducing the dilution of the matrix to the clad material and refining the grain structure of the coating.

[0051] According to some embodiments of the present invention, the Ni-based alloy containing Mo and Cr can be Ni-Cr-Mo series alloys of various standard grades, or non-standard grade alloys designed according to actual working conditions, preferably one or more of Hastelloy C22, C276, C2000 alloys, Inconel625, Inconel718 alloys, Nicrofer 3127hMo (Alloy 31), and Nicrofer5923hMo (Alloy 59) alloys.

[0052] According to some embodiments of the present invention, the average particle size of the powder of the Ni-based alloy containing Mo and Cr is 80 - 100 μm.

[0053] According to some embodiments of the present invention, the average particle size of the La2O3 powder is 5 - 10 μm. The appearance of the La2O3 powder is white.

[0054] The second aspect of the present invention provides a corrosion-resistant metal composite coating, which is obtained by laser cladding a corrosion-resistant metal composite coating on a substrate.

[0055] According to some embodiments of the present invention, the thickness of the composite coating is 0.3 mm - 1 mm.

[0056] According to some embodiments of the present invention, the temperature that the corrosion-resistant metal composite coating can withstand is 600 - 1000 °C.

[0057] According to some embodiments of the present invention, the concentration of HCl that the corrosion-resistant metal composite coating can withstand is 1 - 10 vol%.

[0058] According to some embodiments of the present invention, the substrate can be any type in the art and can be made of any material for an incinerator, such as but not limited to stainless steel, heat-resistant steel, carbon steel, etc. Specifically, for example, it is 45# steel, 316 stainless steel, 12CrlMoV, 15CrMo. In one embodiment, the thickness of the substrate is, for example, 5 - 15 mm, and specifically can be 9 mm, 12 mm. The substrate of the present invention can also be a steel plate, and the specification of the steel plate is, for example, 100 mm × 100 mm × 10 mm.

[0059] The third aspect of the present invention provides a method for preparing the above corrosion-resistant metal composite coating, comprising the following steps:

[0060] Step 1, mixing a Ni-based alloy containing Mo and Cr with La2O3 powder to obtain a mixed powder;

[0061] Step 2, laser cladding the mixed powder obtained in Step 1 on a substrate.

[0062] The schematic diagram of the preparation process of the corrosion-resistant metal composite coating of the present invention is as Figure 1 shown.

[0063] According to some embodiments of the present invention, the conditions of the laser cladding include: the laser power is 1600 - 2000W, the cladding speed is 2 - 4mm / s, and the overlapping rate is 30 - 60%.

[0064] According to some embodiments of the present invention, the laser cladding adopts a coaxial powder feeding method or a powder laying method. The powder feeding speed is 20 - 30g / min.

[0065] According to some embodiments of the present invention, an inert gas is continuously introduced during laser cladding. The flow rate of the inert gas is 9 - 15L / min. The present invention does not particularly limit the inert gas, such as argon, nitrogen, etc.

[0066] According to some embodiments of the present invention, the conditions of the mixing include but are not limited to: mixing in a vacuum or inert atmosphere ball mill for 2 - 5h. The Ni-based alloy containing Mo and Cr and the La2O3 powder are mixed in a vacuum or inert atmosphere ball mill. Preferably, the mixing time is 2 - 5h. For example but not limited to, mixing the Hastelloy C22 alloy powder and the La2O3 powder in a vacuum or inert atmosphere ball mill, and the mixing time is, for example, 2 - 5h, preferably 2h.

[0067] According to some embodiments of the present invention, the substrate can be any type in the art and can be made of any material for an incinerator, such as but not limited to stainless steel, heat-resistant steel, carbon steel, etc. Specifically, for example, it is 45# steel, 316 stainless steel, 12CrlMoV, 15CrMo. In one embodiment, the thickness of the substrate is, for example, 5 - 15mm, and specifically, it can be 9mm, 12mm. The substrate of the present invention can also be a steel plate, and the specification of the steel plate is, for example, 100mm×100mm×10mm.

[0068] According to some embodiments of the present invention, preferably, the substrate is pretreated before laser cladding. More preferably, the pretreatment is: first, the surface of the substrate is polished with a angle grinder and sandpaper, then ultrasonically cleaned with anhydrous ethanol, and dried.

[0069] According to some specific embodiments of the present invention, first, the target nickel-based alloy powder and La2O3 powder with a specific content are mechanically mixed, and then a laser melting method is used with process parameters within a specific range to clad the mixed powder on the substrate to obtain a nickel-based alloy coating. This coating not only has excellent corrosion resistance but also has a high coating hardness. At the same time, the laser cladding method adopted by the present invention has the characteristics of high energy, fast cooling rate, small dilution rate, good metallurgical bonding between the coating and the substrate, a wide range of clad materials, and convenient automation control.

[0070] The fourth aspect of the present invention provides the application of the above-mentioned corrosion-resistant metal composite coating and / or the above-mentioned corrosion-resistant metal composite coating in the field of waste incineration, especially in waste incinerators.

[0071] The present invention will be further described below through examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or directly purchased from the market.

[0072] Example 1

[0073] (1) Prepare the corrosion-resistant metal composite coating:

[0074] By weight percentage, it contains Hastelloy C22: 99 wt%, La2O3: 1 wt%. Among them, the weight ratio of Mo element to La element is 15:1. The average particle size of the Hastelloy C22 powder is 80 μm, and the average particle size of the La2O3 powder is 5 μm.

[0075] (2) Prepare the corrosion-resistant metal composite coating:

[0076] S1: Substrate pretreatment: Use 12Cr1MoV with a specification of 100 mm × 100 mm × 10 mm as the substrate. First, use a angle grinder and sandpaper to polish the substrate surface, and then perform ultrasonic cleaning with anhydrous ethanol and dry it.

[0077] S2: Weigh the corrosion-resistant metal composite coating: Weigh the above-mentioned Hastelloy C22 powder and La2O3 as the cladding powder according to the above ratio.

[0078] S3: Powder mixing: Place the powder in S2 into a vacuum ball mill for mechanical mixing, and the mixing time is 2 h.

[0079] S4: Laser cladding: Introduce the uniformly mixed powder in S3 into a coaxial powder feeder, with a coaxial powder feeding speed of 20 g / min. Make the laser perpendicular to the surface of the substrate to be cladded to prepare a corrosion-resistant metal composite coating. The specific laser cladding process parameters are: laser power 1600 W, cladding speed 2 mm / s, overlap rate 50%, and argon gas flow rate 15 L / min. A corrosion-resistant metal composite coating with a thickness of 0.8 mm is prepared.

[0080] Grind and polish the surface and cross-section of the prepared corrosion-resistant metal composite coating, and subject the specimen to a 60-hour high-temperature chlorine corrosion test at 900 °C in a dry atmosphere of 5 vol.% HCl - 5 vol.% O2 - 90 vol.% N2. Through SEM scanning electron microscopy and EDS energy spectrum analysis, the following is obtained Figure 2 The cross-sectional morphology diagram of the high-temperature chlorine corrosion layer and the EDS element distribution diagram as shown. Through Figure 2 It can be seen that a relatively dense and thin Cr2O3 layer is formed in the corrosion layer, and there is enrichment of La, Mo, and O elements in some surface areas of the corrosion layer, which means that La4MoO9 is formed in the corrosion layer, indicating that the corrosion layer of the coating is relatively dense and thin at this time, and the corrosion rate is low. The weight gain of this example is 0.3597 mg / mm 2 .

[0081] Comparative Example 1

[0082] (1) Prepare a corrosion-resistant metal composite coating:

[0083] By weight percentage, it contains Hastelloy C22: 100% by weight. Among them, the average particle size of the Hastelloy C22 powder is 80 μm.

[0084] (2) Prepare a corrosion-resistant metal composite coating:

[0085] S1: Substrate pretreatment: Use 316 stainless steel with a specification of 100 mm × 100 mm × 10 mm as the substrate, and successively polish the substrate surface with an angle grinder and sandpaper, then ultrasonically clean it with absolute ethanol and dry it.

[0086] S2: Powder weighing: Weigh Hastelloy C22 powder.

[0087] S3: Powder ball milling: Place the powder in S2 into a vacuum ball mill for mechanical ball milling, and the ball milling time is 2 h.

[0088] S4: Laser cladding: Introduce the ball-milled powder in S3 into a coaxial powder feeder, with a coaxial powder feeding speed of 20 g / min. Make the laser perpendicular to the surface of the substrate to be clad and prepare multi-pass coatings. The specific process parameters for laser cladding are: laser power 1600 W, cladding speed 2 mm / s, overlapping rate 50%, and argon gas flow rate 15 L / min. A coating with a thickness of 0.8 mm is prepared.

[0089] Polish the surface and cross-section of the coating prepared in Comparative Example 1, and perform chlorine corrosion test for 60 h in an atmosphere of 5% vol.% HCl - 5% vol.% O2 - 90% vol.% N2 at 900 °C to obtain Figure 3 the morphology diagram of the corrosion layer and the EDS element distribution diagram of the cross-section of the coating, Figure 3 the thickness of the corrosion layer in it increases to 14.8 μm, and the thickness of the Cr2O3 layer also increases significantly, indicating that the corrosion layer of the coating in this comparative example has a relatively large thickness value and there are holes and it is not dense. The weight gain of this comparative example is 0.7497 mg / mm 2 .

[0090] Example 2

[0091] (1) Prepare the corrosion-resistant metal composite coating:

[0092] By weight percentage, it contains Hastelloy C22: 99 wt%, La2O3: 1 wt%, where the weight ratio of Mo element to La element is 15:1, the average particle size of the Hastelloy C22 powder is 80 μm, and the average particle size of the La2O3 powder is 5 μm.

[0093] (2) Prepare the corrosion-resistant metal composite coating:

[0094] S1: Substrate pretreatment: Use 316 stainless steel with a specification of 100 mm × 100 mm × 10 mm as the substrate, polish the substrate surface with a angle grinder and sandpaper successively, then perform ultrasonic cleaning with anhydrous ethanol and dry it.

[0095] S2: Powder weighing: Weigh the above-mentioned Hastelloy C22 powder and La2O3 as the cladding powder according to the above ratio.

[0096] S3: Powder mixing: Place the powder in S2 into an argon atmosphere ball mill for mechanical mixing, and the mixing time is 2 h.

[0097] S4: Laser cladding: Introduce the uniformly mixed powder in S3 into a coaxial powder feeder, with a coaxial powder feeding speed of 20 g / min. Make the laser perpendicular to the surface of the substrate to be clad, and prepare a multi-pass corrosion-resistant metal composite coating. The specific process parameters of laser cladding are: laser power 1600 W, cladding speed 2 mm / s, overlapping rate 50%, and argon gas flow rate 15 L / min. A corrosion-resistant metal composite coating with a thickness of 0.8 mm is prepared.

[0098] The surface of the prepared multi-pass coating is polished, and under the temperature condition of 900 °C, in a dry 5% vol.% HCl - 5% vol.% O2 - 90% vol.% N2 atmosphere environment, a 60-hour high-temperature chlorine corrosion test is carried out, and the Figure 4 coating high-temperature chlorine corrosion XRD shown is obtained, and the peak of La4MoO9 is clearly observed. Its weight gain is 0.172 mg / mm 2 . Compared with the surface average hardness value of 329.4 HV in Comparative Example 1, the surface average hardness value of this example is increased to 387.8 HV.

[0099] Example 3

[0100] (1) Prepare the corrosion-resistant metal composite coating:

[0101] By weight percentage, it contains Hastelloy C22: 99 wt%, La2O3: 1 wt%. Among them, the weight ratio of Mo element to La element is 15:1. The average particle size of Hastelloy C22 powder is 95 μm, and the average particle size of La2O3 powder is 8 μm.

[0102] (2) Prepare the corrosion-resistant metal composite coating:

[0103] S1: Substrate pretreatment: Use 316 stainless steel with a specification of 100 mm × 100 mm × 10 mm as the substrate. First, use a angle grinder and sandpaper to polish the surface of the substrate, then ultrasonically clean it with absolute ethanol, and dry it.

[0104] S2: Powder weighing: Weigh the above-mentioned Hastelloy C22 powder and La2O3 as the cladding powder according to the above ratio.

[0105] S3: Powder mixing: Place the powder in S2 into a vacuum ball mill for mechanical mixing, and the mixing time is 2 h.

[0106] S4: Laser cladding: Introduce the uniformly mixed powder in S3 into a coaxial powder feeder, with a coaxial powder feeding speed of 20 g / min. Make the laser perpendicular to the surface of the substrate to be clad, and prepare a multi-pass corrosion-resistant metal composite coating. The specific process parameters are: laser power 1600 W, cladding speed 2 mm / s, overlapping rate 50%, and argon gas flow rate 15 L / min. A corrosion-resistant metal composite coating with a thickness of 1 mm is prepared.

[0107] Perform a corrosion resistance test experiment on the coatings prepared in Example 3 and Comparative Example 1. Use a standard three-electrode system for testing in an electrochemical workstation. Use a pure platinum sheet as the counter electrode and a calomel electrode as the reference electrode. Select 1 M HCl solution as the electrolyte. The impedance diagram and polarization curve are measured as Figure 5 and Figure 6 shown. After adding a certain content of La2O3 to the Ni-Cr-Mo series alloy, the impedance spectrum radius of the coating increases significantly, the self-corrosion potential shifts positively, and the corrosion resistance is improved. Perform an EDS scan on the coatings prepared in Example 3 and Comparative Example 1, and obtain the results as Figure 7 shown. It can be seen from Figure (b) that the contents of impurity elements P and Si in Example 3 are reduced to 0, while the contents of impurity elements P and Si in Comparative Example 1 in Figure (a) are 2.3 wt.% and 1.8 wt.% respectively.

[0108] Example 4

[0109] According to the method of Example 2, only different is that Hastelloy C22 is replaced by Nicrofer 3127hMo (Alloy 31), and the average particle size of the powder is 84 μm. Finally, a corrosion-resistant metal composite coating with a thickness of 0.8 mm is obtained.

[0110] After subjecting the coating of this example to a high-temperature chlorine corrosion test for 60 h in a dry 5% vol.% HCl - 5% vol.% O2 - 90% vol.% N2 atmosphere environment at a temperature of 900 °C, its weight gain is 0.597 mg / mm 2 , which is a reduction of 0.1527 mg / mm in weight gain compared to Comparative Example 1 2 .

[0111] Example 5

[0112] According to the method of Example 2, only different is that Hastelloy C22 is replaced by Inconel 625, and the average particle size of the powder is 95 μm. Finally, a corrosion-resistant metal composite coating with a thickness of 0.8 mm is obtained.

[0113] The coatings prepared in Example 5 and Comparative Example 1 were subjected to a 60-hour high-temperature chlorine corrosion test in a dry 5% vol.% HCl - 5% vol.% O2 - 90% vol.% N2 atmosphere at a temperature of 900 °C, and the weight change curve shown by Figure 8 was obtained. It can be clearly seen that the weight gain of Example 5 was smaller, highlighting its better high-temperature chlorine corrosion resistance.

[0114] Example 6

[0115] According to the method of Example 2, only the laser power was 2000 W, the cladding speed was 4 mm / s, and the overlap rate was 60%. Finally, a corrosion-resistant metal composite coating with a thickness of 0.8 mm was obtained.

[0116] After the coating of this example was subjected to a 60-hour high-temperature chlorine corrosion test in a dry 10% vol.% HCl - 5% vol.% O2 - 90% vol.% N2 atmosphere at a temperature of 900 °C, its weight gain was 0.3639 mg / mm 2 , which was a reduction of 0.3858 mg / mm in weight gain compared to Comparative Example 1 2 .

[0117] Example 7

[0118] According to the method of Example 2, only the powder feeding speed was 30 g / min. Finally, a corrosion-resistant metal composite coating with a thickness of 1 mm was obtained. Finally, a corrosion-resistant metal composite coating with a thickness of 0.8 mm was obtained.

[0119] After the coating of this example was subjected to a 60-hour high-temperature chlorine corrosion test in a dry 10% vol.% HCl - 5% vol.% O2 - 90% vol.% N2 atmosphere at a temperature of 900 °C, its weight gain was 0.3924 mg / mm 2 , which was a reduction of 0.3573 mg / mm in weight gain compared to Comparative Example 1 2 .

[0120] Example 8

[0121] According to the method of Example 2, only the corrosion-resistant metal composite coating:

[0122] By weight percentage, it contained Hastelloy C22: 99.4% by weight, La2O3: 0.6% by weight. Finally, a corrosion-resistant metal composite coating with a thickness of 0.8 mm was obtained.

[0123] The coating of this example was dried in an atmosphere of 10 vol.% HCl - 5 vol.% O2 - 90 vol.% N2 at a temperature of 900 °C. After 60 h of high-temperature chlorine corrosion test, its weight gain was 0.3093 mg / mm 2 , and the weight gain was reduced by 0.4404 mg / mm compared with that of Comparative Example 1 2 .

[0124] Example 9

[0125] According to the method of Example 2, the only difference is the corrosion-resistant metal composite coating:

[0126] By weight percentage, it contains Hastelloy C22: 98.5 wt%, La2O3: 1.5 wt%. Finally, a corrosion-resistant metal composite coating with a thickness of 0.8 mm was obtained.

[0127] The coating of this example was dried in an atmosphere of 10 vol.% HCl - 5 vol.% O2 - 90 vol.% N2 at a temperature of 900 °C. After 60 h of high-temperature chlorine corrosion test, its weight gain was 0.4393 mg / mm 2 , and the weight gain was reduced by 0.3104 mg / mm compared with that of Comparative Example 1 2 .

[0128] Example 10

[0129] According to the method of Example 2, the only difference is the corrosion-resistant metal composite coating:

[0130] By weight percentage, it contains Hastelloy C22: 98.8 wt%, La2O3: 1.2 wt%. Finally, a corrosion-resistant metal composite coating with a thickness of 0.8 mm was obtained.

[0131] The coating of this example was dried in an atmosphere of 10 vol.% HCl - 5 vol.% O2 - 90 vol.% N2 at a temperature of 900 °C. After 60 h of high-temperature chlorine corrosion test, its weight gain was 0.4952 mg / mm 2 , and the weight gain was reduced by 0.2545 mg / mm compared with that of Comparative Example 1 2 .

[0132] Example 11

[0133] According to the method of Example 2, the only difference is the corrosion-resistant metal composite coating:

[0134] By weight percentage, it contains Hastelloy C22: 99.99% by weight and La2O3: 0.01% by weight. Finally, a corrosion-resistant metal composite coating with a thickness of 0.8 mm is obtained.

[0135] After subjecting the coating of this example to a high-temperature chlorine corrosion test for 60 h in a dry 10% vol.% HCl - 5% vol.% O2 - 90% vol.% N2 atmosphere environment at a temperature of 900 °C, its weight gain is 0.5821 mg / mm 2 , which is a reduction of 0.1676 mg / mm in weight gain compared to Comparative Example 1. 2 .

[0136] Example 12

[0137] According to the method of Example 2, the only difference is the corrosion-resistant metal composite coating:

[0138] By weight percentage, it contains Hastelloy C22: 98% by weight and La2O3: 2% by weight. Finally, a corrosion-resistant metal composite coating with a thickness of 0.8 mm is obtained.

[0139] After subjecting the coating of this example to a high-temperature chlorine corrosion test for 60 h in a dry 10% vol.% HCl - 5% vol.% O2 - 90% vol.% N2 atmosphere environment at a temperature of 900 °C, its weight gain is 0.6353 mg / mm 2 , which is a reduction of 0.1144 mg / mm in weight gain compared to Comparative Example 1. 2 .

[0140] Example 13

[0141] According to the method of Example 2, the only difference is the corrosion-resistant metal composite coating:

[0142] By weight percentage, it contains Hastelloy C22: 99.5% by weight, La2O3: 0.5% by weight, and the weight ratio of Mo element to La element is 15:0.5. Finally, a corrosion-resistant metal composite coating with a thickness of 0.8 mm is obtained.

[0143] After subjecting the coatings prepared in Example 13 and Comparative Example 1 to a high-temperature chlorine corrosion test for 60 h in a dry 5% vol.% HCl - 5% vol.% O2 - 90% vol.% N2 atmosphere environment at a temperature of 900 °C, a weight change curve graph shown by Figure 9 is obtained. It can be clearly seen that the weight gain of Example 13 is smaller than that of Comparative Example 1, highlighting its better high-temperature chlorine corrosion resistance.

[0144] Example 14

[0145] According to the method of Example 2, only different in that the corrosion-resistant metal composite coating:

[0146] By weight percentage, it contains Hastelloy C22: 99.2% by weight, La2O3: 0.8% by weight, and the weight ratio of Mo element to La element is 15:3. Finally, a corrosion-resistant metal composite coating with a thickness of 0.8 mm is obtained.

[0147] The coatings prepared in Example 14 and Comparative Example 1 were subjected to a high-temperature chlorine corrosion test for 60 h in a dry 5% vol.% HCl - 5% vol.% O2 - 90% vol.% N2 atmosphere environment at a temperature of 900 °C, and the obtained Figure 10 The corrosion kinetic curve shown. It can be clearly seen that the weight gain of Example 14 is smaller than that of Comparative Example 1, highlighting its better high-temperature chlorine corrosion resistance.

[0148] Comparative Example 2

[0149] According to the method of Example 2, only different in that the corrosion-resistant metal composite coating:

[0150] By weight percentage, it contains Hastelloy C22: 99.7% by weight, La2O3: 0.3% by weight, and the molar ratio of Mo element to La element is 15:0.3. Finally, a corrosion-resistant metal composite coating with a thickness of 0.8 mm is obtained.

[0151] After the coating of this comparative example was subjected to a high-temperature chlorine corrosion test for 60 h in a dry 10% vol.% HCl - 5% vol.% O2 - 90% vol.% N2 atmosphere environment at a temperature of 900 °C, its weight gain was 0.9721 mg / mm 2 , which is an increase of 0.8001 mg / mm in weight gain compared to Example 2 2 .

[0152] Comparative Example 3

[0153] According to the method of Example 2, only different in that the corrosion-resistant metal composite coating:

[0154] By weight percentage, it contains Hastelloy C22: 99.8% by weight, La2O3: 0.2% by weight, and the weight ratio of Mo element to La element is 15:0.2. Finally, a corrosion-resistant metal composite coating with a thickness of 0.8 mm is obtained.

[0155] The surface and cross-section of the coating prepared in Comparative Example 3 were polished, and a chlorine corrosion test was carried out for 60 h in a dry 5% vol.% HCl - 5% vol.% O2 - 90% vol.% N2 atmosphere environment at 900 °C, and the obtainedFigure 11 Morphology diagram of the corrosion layer of the coating cross-section and EDS element distribution diagram Figure 11 In Figure 11 , the thickness of the corrosion layer increased to 23.46 μm, and the thickness of the Cr2O3 layer increased significantly, indicating that the corrosion layer of the coating in this comparative example has a large thickness value, and there are a large number of pores, and the corrosion layer is loose and not dense.

[0156] Comparative Example 4

[0157] According to the method of Example 2, the only difference is the corrosion-resistant metal composite coating:

[0158] By weight percentage, it contains Hastelloy C22: 95% by weight, La2O3: 5% by weight, and the weight ratio of Mo element to La element is 3:1. Finally, a corrosion-resistant metal composite coating with a thickness of 0.8 mm is obtained.

[0159] The coating prepared in Comparative Example 4 was dried at 900 °C in an atmosphere of 5% vol.% HCl - 5% vol.% O2 - 90% vol.% N2, and a chlorine corrosion test was carried out for 60 h to obtain Figure 12 The coating corrosion kinetics curve diagram Figure 12 In Figure 12 , the weight gain of Comparative Example 4 is greater than that of Example 2, indicating that the corrosion resistance of the coating in this comparative example is worse than that of the coating in Example 2.

[0160] Comparative Example 5

[0161] According to the method of Example 2, the only difference is that in the corrosion-resistant metal composite coating, La2O3 is replaced by MnO2. Finally, a corrosion-resistant metal composite coating with a thickness of 0.8 mm is obtained.

[0162] After the coating of this comparative example was subjected to a 60 h high-temperature chlorine corrosion test in a dry atmosphere of 10% vol.% HCl - 5% vol.% O2 - 90% vol.% N2 at a temperature of 900 °C, its weight gain was 0.9223 mg / mm 2 , compared with the weight gain of Example 2, it increased by 0.7503 mg / mm 2 .

[0163] Comparative Example 6

[0164] According to the method of Example 2, the only difference is that in the corrosion-resistant metal composite coating, La2O3 is replaced by CeO2. Finally, a corrosion-resistant metal composite coating with a thickness of 0.8 mm is obtained.

[0165] The coating of this comparative example was subjected to a high-temperature chlorine corrosion test for 60 h in a dry 10% vol.% HCl - 5% vol.% O2 - 90% vol.% N2 atmosphere at a temperature of 900 °C, and its weight gain was 0.8520 mg / mm 2 , and the weight gain increased by 0.68 mg / mm compared to that of Example 2 2 .

[0166] Comparative Example 7

[0167] According to the method of Example 2, the only difference is that in the corrosion-resistant metal composite coating, La2O3 was replaced with ZrO2. Finally, a corrosion-resistant metal composite coating with a thickness of 0.8 mm was obtained.

[0168] The coating of this comparative example was subjected to a high-temperature chlorine corrosion test for 60 h in a dry 10% vol.% HCl - 5% vol.% O2 - 90% vol.% N2 atmosphere at a temperature of 900 °C, and its weight gain was 0.8973 mg / mm 2 , and the weight gain increased by 0.7253 mg / mm compared to that of Example 2 2 .

[0169] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and 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 corrosion-resistant metal composite coating, characterized in that, The coating includes La2O3 powder and a Ni-based alloy containing Mo and Cr; wherein, the weight ratio of the Mo element to the La element is 15:0.5 - 3.

2. The composite coating according to claim 1, characterized in that, The composite coating forms a Cr2O3-La4MoO9 protective layer at 600 - 1000 °C.

3. The composite coating according to claim 1 or 2, characterized in that, By weight percentage, the corrosion-resistant metal composite coating contains 0.1 - 1.5 wt% of La2O3 and 98.5 - 99.9 wt% of a Ni-based alloy containing Mo and Cr; preferably, by weight percentage, the corrosion-resistant metal composite coating contains 0.5 - 1.5 wt% of La2O3 and 98.5 - 99.5 wt% of a Ni-based alloy containing Mo and Cr.

4. The composite coating according to any one of claims 1-3, characterized in that, The Ni-based alloy containing Mo and Cr is selected from one or more of Hastelloy C22, Hastelloy C276, Hastelloy C2000 alloys, Inconel 625, Inconel718 alloys, Alloy 31, and Alloy 59 alloys.

5. The composite coating according to any one of claims 1 to 4, characterized in that, The average particle size of the powder of the Ni-based alloy containing Mo and Cr is 80 - 100 μm, and / or the average particle size of the La2O3 powder is 5 - 10 μm.

6. A corrosion-resistant metal composite coating, characterized in that, The coating is obtained by laser cladding the corrosion-resistant metal composite coating according to any one of claims 1 - 5 on a substrate; Preferably, the thickness of the composite coating is 0.3 mm - 1 mm; Preferably, the temperature that the corrosion-resistant metal composite coating can withstand is 600 - 1000 °C; Preferably, the concentration of HCl that the corrosion-resistant metal composite coating can withstand is 1 - 10 vol%.

7. The method for preparing the corrosion-resistant metal composite coating according to claim 6, characterized in that, It includes the following steps: Step 1, mix the Ni-based alloy containing Mo and Cr with La2O3 powder to obtain a mixed powder; Step 2, laser clad the mixed powder obtained in Step 1 on a substrate.

8. The preparation method according to claim 7, characterized in that, The conditions of the laser cladding include: the laser power is 1600 - 2000 W, the cladding speed is 2 - 4 mm / s, and the overlapping rate is 30 - 60%; and / or, the laser cladding adopts a coaxial powder feeding method or a powder spreading method, preferably, the powder feeding speed is 20 - 30 g / min and / or, an inert gas is continuously introduced during laser cladding, preferably, the flow rate of the inert gas is 9 - 15 L / min.

9. The preparation method according to claim 7 or 8, characterized in that, The conditions of the mixing include: mixing in a vacuum or inert atmosphere ball mill for 2 - 5 h.

10. Application of the corrosion-resistant metal composite coating according to any one of claims 1 - 5 and / or the corrosion-resistant metal composite coating according to claim 6 in the field of waste incineration, especially in waste incinerators.

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