A spraying material and spraying process for the heated surface of a waste incineration boiler tube

Abstract

The present invention belongs to the technical field of surface treatment of incineration boiler tubes, and specifically relates to a spraying material for the heated surface of a waste incineration boiler tube and a spraying process thereof. The spraying material is an iron-nickel-based alloy coating material, the elemental composition of which is mainly Ni, Fe, Co, and Al. It belongs to an irregular fine lamellar eutectic structure (eutectic medium entropy alloy) composed of an AlNi-B2-rich phase and a Fe-FCC-rich phase. At the same time, the alloy coating has excellent mechanical properties, high strength and corrosion resistance. The present invention further improves its wear resistance while maintaining corrosion resistance by replacing the more expensive Ni in the existing nickel-based alloy with inexpensive Fe, and significantly reduces the cost of raw materials. In addition, the present invention adopts a laser cladding process to make the material adhere to the heated surface of the waste incineration boiler tube, does not contain pores and cracks, has no component segregation phenomenon, and has a low processing cost.

Description

Technical Field

[0001] The invention belongs to the technical field of surface treatment of incineration boiler tubes, and in particular relates to a spraying material for the heated surface of a garbage incineration boiler tube and a spraying process thereof. Background Art

[0002] By burning garbage in a waste incineration boiler and transferring heat energy through the boiler tubes to heat water, generating steam that drives a generator to generate electricity, the waste can be quickly and harmlessly treated and fully reused. In addition to the high-temperature and high-pressure resistance required of ordinary boilers, the incineration process produces large amounts of corrosive gases due to the unstable calorific value of garbage and incomplete combustion, which in turn causes high-temperature corrosion in the pipes. Furthermore, small solid particles that are incompletely or unable to be incinerated during the waste incineration process will move within the boiler with the high-temperature airflow, continuously impacting the boiler tube walls, causing the coating to fall off and fail, which to a certain extent reduces the pipe's service life.

[0003] To extend the service life of waste incineration boiler pipes, a protective coating needs to be sprayed onto the heated surfaces. Currently, nickel-based alloys (such as NiCr and NiCrAl) are commonly used as surface coatings for metal substrates both domestically and internationally. However, while these coatings offer strong corrosion resistance, they are relatively expensive and are generally used in industries such as aerospace and petroleum for precision components requiring fatigue resistance, corrosion resistance, wear resistance, and high temperature resistance. Iron-based alloy powders also offer considerable wear resistance and are relatively inexpensive. Their application in protective coatings for waste incineration boiler pipes would be highly cost-effective.

[0004] Therefore, it is necessary to develop a low-cost, high-corrosion-resistant and wear-resistant coating for the heating surface of waste incineration boiler pipes using iron-based alloy powder to solve the above problems. Summary of the Invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the present invention proposes an iron-nickel-based alloy spraying material for the heated surface of a waste incineration boiler tube. The alloy coating is composed of an irregular, fine lamellar eutectic structure rich in AlNi-B2 phase and Fe-FCC phase, has high strength and corrosion resistance, and solves the problem of high cost of existing nickel-based coating alloys.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A first aspect of the present invention provides a spraying process for spraying a material on a heated surface of a waste incineration boiler tube, comprising the following steps:

[0008] S1. Weigh a single-element iron-nickel alloy raw material composed of Ni, Fe, Co, and Al, where, by mass percentage, Ni: 38.0-42.0%, Fe: 28.0-32.0%, Co: 19.0-23.0%, and Al: 7.0%-11.0%;

[0009] S2, Si powder and B powder are mixed with the iron-nickel alloy single substance raw material, and Ni is obtained after ball milling. 38-42 -Fe 28-32 -Co 19-23 -Al 7-11 Iron-nickel alloy mixed powder, wherein the amount of Si powder and B powder is 0.4-0.6% of the total mass of the iron-nickel alloy single substance raw material;

[0010] S3, for you 38-42 -Fe 28-32 -Co 19-23 -Al 7-11 After the iron-nickel alloy mixed powder is dried, it is mixed with a binder and pre-placed on the heated surface substrate of the waste incineration boiler tube. The pre-coating is dried and preheated before cladding treatment;

[0011] S4. Performing aging treatment on the cladding-completed waste incineration boiler tube to obtain the surface spraying material.

[0012] By partially replacing the more expensive Ni in existing nickel-based alloys with inexpensive Fe, this invention further improves wear resistance while maintaining corrosion resistance and significantly reduces raw material costs. Furthermore, the laser cladding process used in this invention allows the material to adhere to the heated surface of waste incineration boiler tubes. This results in a product that is free of pores, cracks, and component segregation, while also offering low processing costs, potentially addressing the high cost of existing nickel-based coating alloys.

[0013] Preferably, calculated by mass percentage, Ni: 38.0-40.0%, Fe: 30.0-32.0%, Co: 20.0%, and Al: 10.0%.

[0014] Preferably, the ball milling in step S2 is performed using a planetary ball mill, with a drum speed of 200-300 rpm, a ball-to-material ratio of 50-70 h, and a powder particle size in the range of 20-90 μm.

[0015] Preferably, the drying process in step S3 is carried out for 8 to 12 hours at a temperature of 70 to 90°C.

[0016] Preferably, the cladding treatment in step S3 is performed using laser cladding technology, the power of the laser cladding is 1400-1800 W, the spot diameter is 3-5 mm, the scanning speed is 16-22 mm / s, and the shielding gas is Ar gas.

[0017] Preferably, the aging treatment in step S4 is performed at a temperature of 400-640° C. for 96-144 hours.

[0018] Preferably, the thickness of the pre-coating layer in step S3 is 1-1.8 mm.

[0019] Preferably, the adhesive in step S3 is selected from epoxy resin adhesive.

[0020] Preferably, the purity of the Al, Co, Fe, and Ni metal element raw materials in step S1 is ≥ 99.9 wt.%.

[0021] Preferably, in step S3, the pre-coating layer is dried at 90-100° C. and preheated for 30-60 minutes before the cladding process is performed.

[0022] Preferably, the heated surface substrate of the waste incineration boiler tube in step S3 is polished to a metallic luster before pre-coating, and then cleaned with ethanol.

[0023] The second aspect of the present invention provides a spraying material for the heated surface of a waste incineration boiler tube prepared by the spraying process described in the first aspect.

[0024] The heated surface spraying material of the waste incineration boiler tube prepared by the present invention is an iron-nickel-based alloy coating material, the elemental composition of which is mainly Ni, Fe, Co, and Al, and the corresponding mass percentages of each element are Ni: 38.0-42.0%, Fe: 28.0-32.0%, Co: 19.0-23.0%, and Al: 7.0%-11.0%. The coating material mainly contains four elements. Adding aluminum to the iron-cobalt-nickel alloy promotes the formation of AlNi-rich BCC phase, which together with the FCC phase constitutes an FCC-B2 two-phase iron-nickel-based eutectic medium entropy alloy with irregular fine lamellar spacing of 100-300nm. The spraying material is oxidized at 800°C for 100 hours and has an oxidation weight gain of less than 0.9g·m -2 , weight gain rate is less than 0.009g·m -2 ·h -1 ; Soaked in 0.005mol / L H2S04+0.25mol / L Na2S04 solution for 12h, corrosion potential E corr Greater than -0.3V, corrosion current density I corr Less than 3×10 -6 A / cm 2 It can be seen that the heated surface spraying material of the waste incineration boiler tube prepared by the method of the present invention has high strength and corrosion resistance, which meets the use requirements of the waste incineration boiler pipeline.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The mass percentage of Ni in existing nickel-based coating alloys is 55%-70%, which is relatively expensive. To this end, the present invention provides a waste incineration boiler pipe heating surface spraying material, which utilizes the "cocktail effect" of medium-entropy alloys and uses 28-32% of low-cost Fe to partially replace the more expensive Ni in existing nickel-based alloys. While maintaining corrosion resistance, its wear resistance is further improved, and at the same time, the raw material cost of the coating on the heating surface of the waste incinerator pipe is significantly reduced.

[0027] (2) The heated surface spraying material of the waste incineration boiler tube of the present invention has excellent mechanical properties, a yield strength greater than 522 MPa, a compressive strength greater than 2.5 GPa, and a fracture strain greater than 46%.

[0028] (3) The spraying material for the heated surface of the waste incineration boiler tube of the present invention has excellent high-temperature oxidation resistance, and the weight gain rate after high-temperature oxidation at 800°C for 100 hours is less than 0.1 g·m -2 ·h -1 .

[0029] (4) The spraying material for the heated surface of the waste incineration boiler tube of the present invention has excellent corrosion resistance and has similar corrosion resistance to the existing Ni-based coating alloy. After being immersed in 0.005mol / L H2S04+0.25mol / L Na2S04 solution for 12h, the corrosion potential E corr is -0.3235V, the corrosion current density I corr is 2.7573×10 -6 A / cm 2 .

[0030] (5) The heated surface spraying material of the waste incineration boiler tube of the present invention is composed of an irregular fine lamellar eutectic structure composed of an AlNi-B2-rich phase and an Fe-FCC-rich phase, with an interlamellar spacing of 100-300nm, no pores and cracks, no component segregation, and good surface quality.

[0031] (6) The present invention provides a spraying process for the heated surface of a waste incineration boiler tube. Compared with traditional coating processes, laser cladding can achieve precise local heating, reduce energy loss, increase material utilization, and significantly reduce costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 For You 40 -Fe 30 -Co 20 -Al 10 XRD diffraction pattern of Fe-Ni based alloy coating;

[0033] Figure 2 For You40 -Fe 30 -Co 20 -Al 10 Microstructure of the iron-nickel based alloy coating;

[0034] Figure 3 For You 40 -Fe 30 -Co 20 -Al 10 SEM images and EDS scanning images of the iron-nickel based alloy coating;

[0035] Figure 4 For You 40 -Fe 30 -Co 20 -Al 10 Room temperature compressive stress-strain curves of Fe-Ni based alloy coatings;

[0036] Figure 5 For You 40 -Fe 30 -Co 20 -Al 10 Oxidation weight gain curve of Fe-Ni based alloy coating;

[0037] Figure 6 For You 40 -Fe 30 -Co 20 -Al 10 Polarization curves of Fe-Ni based alloy coatings. DETAILED DESCRIPTION

[0038] The following is a further description of specific embodiments of the present invention. It should be noted that the description of these embodiments is intended to facilitate understanding of the present invention and does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0039] The experimental methods in the following examples are conventional methods unless otherwise specified, and the experimental materials used in the following examples are commercially available unless otherwise specified.

[0040] Example 1: A spraying process for spraying material on the heated surface of a waste incineration boiler tube

[0041] The specific steps of the spraying process are as follows:

[0042] (1) According to the mass percentage of Ni: 40%, Fe: 30%, Co: 20%, and Al: 10%, weigh out the metal element raw materials Ni, Fe, Co, and Al with a purity of ≥ 99.9 wt.%;

[0043] (2) Si powder and B powder were mixed evenly with the iron-nickel alloy single-element raw material, wherein the amount of Si powder and B powder was 0.5% of the total mass of the iron-nickel alloy single-element raw material (Ni, Fe, Co, Al), and the purity of Si powder and B powder was ≥ 99.9wt.%, and then a planetary ball mill was used to mill the raw material at a drum speed of 250 rpm for 60 hours according to a ball-to-material ratio of 10:1 to obtain Ni with a particle size of 20 μm. 40 -Fe 30 -Co 20 -Al 10 Mixed powder of iron-nickel alloy and Si, B (referred to as Ni 40 -Fe 30 -Co 20 -Al 10 Iron-nickel alloy mixed powder);

[0044] (3) Ni was dried in a vacuum oven at 80°C. 40 -Fe 30 -Co 20 -Al 10 The iron-nickel alloy mixed powder was dried for 10 h;

[0045] (4) First, the heated surface of the waste incineration boiler tube was polished to a metallic luster, and then cleaned with anhydrous ethanol. Then, 60% of the total mass of Ni 40 -Fe 30 -Co 20 -Al 10 Iron-nickel alloy mixed powder was mixed with 40% epoxy resin binder and pre-deposited on the heated surface substrate of the waste incineration boiler tube. The pre-deposited layer had a thickness of 1.4 mm. After drying at 95°C and preheating at this temperature for 50 minutes, the cladding process was carried out under the conditions of a laser power of 1600 W, a spot diameter of 4.5 mm, and a scanning speed of 19 mm / s (protective gas was Ar gas).

[0046] (5) The cladding-finished waste incineration boiler tube was placed in a heat treatment furnace and subjected to aging treatment at 520 °C for 120 h. Ni 40 -Fe 30 -Co 20 -Al 10 Iron-nickel based alloy coating.

[0047] Figure 1 For You 40 -Fe 30 -Co 20 -Al 10 The XRD diffraction pattern of the iron-nickel based alloy coating shows that the alloy coating is composed of FCC and B2 phases and has a dual-phase structure. Figure 2For You 40 -Fe 30 -Co 20 -Al 10 The microstructure of the iron-nickel based alloy coating shows that the interlamellar spacing is 100-300nm. Figure 3 For You 40 -Fe 30 -Co 20 -Al 10 SEM images and EDS scanning images of the iron-nickel based alloy coating, in which the dark phase is rich in Al and Ni elements, and the light phase is rich in Fe elements. Figure 1 Can judge Ni 40 -Fe 30 -Co 20 -Al 10 The iron-nickel based alloy coating is a dual-phase structure composed of an AlNi-B2-rich phase and a Fe-FCC-rich phase, and has an irregular fine lamellar structure with an interlamellar spacing of 100-300 nm. Figure 4 For You 40 -Fe 30 -Co 20 -Al 10 The room temperature compressive stress-strain curve of the iron-nickel based alloy coating shows that the alloy coating has excellent mechanical properties, with a yield strength greater than 522 MPa, a compressive strength greater than 2.5 GPa, and a fracture strain exceeding 46%. Figure 5 For You 40 -Fe 30 -Co 20 -Al 10 The weight gain curve of the iron-nickel based alloy coating after oxidation at 800℃ for 100h, in which the weight gain was 0.641g·m after high temperature oxidation at 800℃ for 50h. -2 , weight gain 0.885 g·m after 100 h -2 , the weight gain rate is less than 0.1g·m -2 ·h -1 , indicating that the iron-nickel based alloy coating has excellent high temperature oxidation resistance. Figure 6 For You 40 -Fe 30 -Co 20 -Al 10 Polarization curve of the iron-nickel based alloy coating shows that after the alloy coating is immersed in 0.005mol / L H2SO4+0.25mol / L Na2SO4 solution for 12h, the corrosion potential E corr is -0.3235V, the corrosion current density I corr is 2.7573×10 -6 A / cm 2 , and in the acidic corrosion environment, the corrosion current density I of the existing Ni-based alloy coating iscorr 1.074×10 -6 A / cm 2 [The data comes from the literature: Wu Xiangqing, Hu Huiling, Xie Faqin, et al. Microstructure and corrosion resistance of plasma sprayed nickel-based alloy coating [J]. China Surface Engineering, 2011, 024(005): 13-17.], it can be seen that the corrosion current density of both is 10 -6 Order of magnitude, with similar corrosion resistance.

[0048] Example 2: Spraying process for spraying material on the heated surface of a waste incineration boiler tube

[0049] (1) According to the mass percentage of Ni: 38%, Fe: 32%, Co: 20%, and Al: 10%, weigh out the metal element raw materials Ni, Fe, Co, and Al with a purity of ≥ 99.9 wt.%;

[0050] (2) Si powder and B powder were mixed evenly with the iron-nickel alloy single-element raw material, wherein the amount of Si powder and B powder was 0.5% of the total mass of the iron-nickel alloy single-element raw material (Ni, Fe, Co, Al), and the purity of Si powder and B powder was ≥ 99.9wt.%, and then a planetary ball mill was used to mill for 65 hours at a drum speed of 240 rpm according to a ball-to-material ratio of 10:1 to obtain Ni with a particle size of 25 μm. 38 -Fe 32 -Co 20 -Al 10 Mixed powder of iron-nickel alloy, Si and B (referred to as Ni 40 -Fe 30 -Co 20 -Al 10 Iron-nickel alloy mixed powder);

[0051] (3) Ni was dried in a vacuum oven at 75°C. 38 -Fe 32 -Co 20 -Al 10 The iron-nickel alloy mixed powder was dried for 11 h;

[0052] (4) First, the heated surface of the waste incineration boiler tube was polished to a metallic luster, and then cleaned with anhydrous ethanol. Then, 60% of the total mass of Ni 38 -Fe 32 -Co 20 -Al 10Iron-nickel alloy mixed powder was mixed with 40% epoxy resin binder and pre-deposited on the heated surface substrate of the waste incineration boiler tube. The pre-deposited layer had a thickness of 1.2 mm. After drying at 95°C and preheating at this temperature for 50 minutes, the cladding process was performed at a laser power of 1500 W, a spot diameter of 5 mm, and a scanning speed of 17 mm / s (with Ar as the shielding gas).

[0053] (5) The cladding-finished waste incineration boiler tube was placed in a heat treatment furnace and subjected to aging treatment at 500 °C for 118 h. Ni 40 -Fe 30 -Co 20 -Al 10 Iron-nickel based alloy coating.

[0054] The test results of the coating of this embodiment in terms of XRD diffraction, micrometallography, SEM and EDS scanning, room temperature compressive stress-strain, oxidation weight gain, and polarization are the same or similar to those of Example 1. It is also composed of an irregular fine lamellar eutectic structure rich in AlNi-B2 phase and Fe-FCC phase, and has high strength and corrosion resistance.

[0055] In summary, the alloy coating prepared on the heated surface of waste incineration boiler tubes using the present method exhibits an irregular, fine lamellar eutectic structure composed of an AlNi-B2-rich phase and an Fe-FCC-rich phase, with an interlamellar spacing of 100-200 nm, representing a eutectic medium-entropy alloy. Furthermore, this alloy coating exhibits excellent mechanical properties, with a yield strength exceeding 522 MPa, a compressive strength exceeding 2.5 GPa, and a fracture strain exceeding 46%, meeting the requirements for use in waste incineration boiler pipes and potentially addressing the high cost of existing nickel-based coating alloys.

[0056] The embodiments of the present invention are described in detail above, but the present invention is not limited to the described embodiments. It is apparent to those skilled in the art that various changes, modifications, substitutions, and variations of these embodiments may be made without departing from the principles and spirit of the present invention, and the changes still fall within the scope of protection of the present invention.

Claims

1. A spraying process for spraying material on the heated surface of a waste incineration boiler tube, characterized in that: The following steps are involved: S1. Weigh a single-element iron-nickel alloy raw material composed of Ni, Fe, Co, and Al, where, by mass percentage, Ni: 38.0-42.0%, Fe: 28.0-32.0%, Co: 19.0-23.0%, and Al: 7.0%-11.0%; S2, Si powder and B powder are mixed with the iron-nickel alloy single substance raw material, and Ni is obtained after ball milling. 38-42 -Fe 28-32 -Co 19-23 -Al 7-11 Iron-nickel alloy mixed powder, wherein the amount of Si powder and B powder is 0.4-0.6% of the total mass of the iron-nickel alloy single substance raw material; S3, for you 38-42 -Fe 28-32 -Co 19-23 -Al 7-11 After the iron-nickel alloy mixed powder is dried, it is mixed with a binder and pre-placed on the heated surface substrate of the waste incineration boiler tube. The pre-coating is dried and preheated before cladding treatment; S4. Performing aging treatment on the cladding-completed waste incineration boiler tube to obtain the surface spraying material.

2. The spraying process of the heated surface spraying material of the waste incineration boiler tube according to claim 1 is characterized in that: In terms of mass percentage, Ni: 38.0-40.0%, Fe: 30.0-32.0%, Co: 20.0%, Al: 10.0%.

3. The spraying process of the spraying material on the heated surface of the waste incineration boiler tube according to claim 1 is characterized in that: The ball milling in step S2 is performed using a planetary ball mill with a drum speed of 200-300 rpm, a ball milling time of 50-70 h, a ball-to-material ratio of 10:1, and a powder particle size in the range of 20-90 μm.

4. The spraying process of the heated surface spraying material of the waste incineration boiler tube according to claim 1 is characterized in that: The drying time in step S3 is 8 to 12 hours and the temperature is 70 to 90°C.

5. The spraying process of the spraying material on the heated surface of the waste incineration boiler tube according to claim 1 is characterized in that: The cladding treatment in step S3 is performed using laser cladding technology. The power of the laser cladding is 1400-1800 W, the spot diameter is 3-5 mm, the scanning speed is 16-22 mm / s, and the protective gas is Ar gas.

6. The spraying process of the spraying material on the heated surface of the waste incineration boiler tube according to claim 1 is characterized in that: The aging treatment in step S4 is performed at a temperature of 400-640° C. for 96-144 hours.

7. The spraying process of the spraying material on the heated surface of the waste incineration boiler tube according to claim 1 is characterized in that: The thickness of the pre-coating layer in step S3 is 1-1.8 mm.

8. The spraying process of the spraying material on the heated surface of the waste incineration boiler tube according to claim 1 is characterized in that: The adhesive in step S3 is selected from epoxy resin adhesive.

9. The spraying process of the spraying material on the heated surface of the waste incineration boiler tube according to claim 1, characterized in that: The purity of the Al, Co, Fe, and Ni metal element raw materials in step S1 is ≥99.9wt.%.

10. A spraying material for the heated surface of a waste incineration boiler tube prepared by the spraying process according to any one of claims 1 to 9.

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