CN111962008A

CN111962008A - Preparation method of boiler four-pipe anticorrosive coating based on laser remelting technology

Info

Publication number: CN111962008A
Application number: CN202010770069.8A
Authority: CN
Inventors: 胡为峰; 汪玉玲; 高冬宇; 肖葵; 杨庆新
Original assignee: Beijing Fengying Annular Eclipse Technology Co ltd; Beijing Saiyi Technology Co ltd
Current assignee: Beijing Fengying Annular Eclipse Technology Co ltd; Beijing Saiyi Technology Co ltd
Priority date: 2020-08-04
Filing date: 2020-08-04
Publication date: 2020-11-20

Abstract

The invention discloses a preparation method of a boiler four-pipe anticorrosive coating based on a laser remelting technology, which comprises the following steps of: (1) cleaning and roughening the surfaces of four pipes of a boiler; (2) spraying corrosion-resistant, erosion-resistant and high-temperature-resistant alloy wire materials by adopting a thermal spraying technology to manufacture a coating; (3) utilizing an X, Y double-shaft laser walking structure to perform step-by-step scanning type laser remelting on the protective coating on the surface of the four tubes of the boiler to form latticed remelted lines; (4) and sealing the remelted coating surface with an enamel sealant. The coating manufactured by the process has a compact and pore-free surface, and the remelted coating and a substrate form a metallurgical bonding remelted line, so that the problems of corrosion diffusion, coating peeling and the like of four pipes of a boiler can be solved, and the service cycle of the four pipes of the boiler is prolonged.

Description

Preparation method of boiler four-pipe anticorrosive coating based on laser remelting technology

Technical Field

The invention relates to the field of boiler corrosion prevention, in particular to a method for manufacturing a boiler four-pipe anticorrosive coating based on a laser remelting technology.

Background

The four pipes of the boiler are generally protected by preparing a coating by adopting a method of spraying alloy wires by adopting a thermal spraying technology, and different alloy wires are selected according to requirements, so that the performances of wear resistance, corrosion resistance, oxidation resistance, high temperature resistance and the like can be obtained. However, the coating prepared by the method is mainly mechanically combined with the substrate, the bonding strength is low, and the coating has certain pores. In the environment of the four tubes of the boiler, the coating needs to be subjected to erosion and abrasion in addition to chemical corrosion at high temperatures. The coating prepared by the thermal spraying method is easy to generate chemical corrosion and erosion, and the corrosion has quite strong infectivity due to pores of the coating and a substrate, namely once the coating has a fragile part to be corroded, the corrosion can be rapidly diffused along the interface of the coating and the substrate, large-area corrosion is formed in a short time, even the coating is peeled off, and the service life of the boiler is greatly reduced.

The invention provides a preparation method of a boiler four-tube anticorrosive coating based on a laser remelting technology, which is characterized in that on the basis of the traditional thermal spraying technology, a X, Y double-axis laser walking structure is utilized to carry out a layered scanning type laser remelting process on a protective coating on the surface of a boiler four-tube to form a latticed remelting line which is metallurgically combined with a matrix, and finally, an enamel hole sealing agent is adopted to seal holes to form a compact surface to prevent corrosive gas from entering the coating and the matrix. Thereby solving the problems of corrosion diffusion, large-area peeling of the coating and the like, reducing the maintenance cost and prolonging the service period.

Disclosure of Invention

The invention provides a preparation method of a boiler four-pipe anticorrosive coating based on a laser remelting technology, which comprises the following steps.

Firstly, cleaning and roughening the surfaces of four pipes of a boiler.

And secondly, spraying alloy wires by using a thermal spraying process to prepare a coating.

And secondly, remelting the surface of the thermal spraying coating by using a laser to form a reticular remelting line.

And fourthly, sealing the remelted coating by using an enamel sealant.

Specifically, the surfaces of the four boiler tubes are cleaned and roughened, and the treated surfaces of the four boiler tubes meet the treatment grade in the standard of steel surface treatment before coating (GB/T8923.1-2011).

Specifically, the spraying material selected for thermal spraying is a high-temperature-resistant, corrosion-resistant and erosion-resistant alloy wire material so as to adapt to the complex environment in the boiler, the thickness of the coating is in the range of 0.3-0.8 mm according to the requirement, the coating is uniform, and the bonding strength with the matrix and the self hardness meet the national standard.

Preferably, the laser selected by the invention is a semiconductor laser or a fiber laser, the power of the laser is 2-10 kW, the wavelength is 900-1100 nm, the collimation distance is 100-300 mm, the focusing distance is 50-300 mm, the shape of a light spot is circular or long-strip-shaped, the circular light spot size is phi 0.5-5 mm, the strip-shaped light spot size is 5-15 mm 2mm, the stroke of a slide rail where the laser is located is 1-10 m, the scanning speed is 0-3 m/s, the width of a remelted line is 0.5-30 mm after remelting, and the thickness of the remelted line is 0.6-0.9 mm.

Specifically, the laser remelting mode of the invention is that an X, Y double-shaft laser walking structure is utilized to perform line-by-line scanning remelting on the anticorrosive coatings of the four boiler pipes, so that grid-shaped remelting lines are formed on the surfaces of the anticorrosive coatings, and the grid-shaped remelting lines are metallurgically bonded with the four boiler pipes.

Preferably, the reticular structure remelted by the laser is a regular polygon generally, and the area of a single grid of the reticular structure is 0.01-1 m²Within.

Preferably, the X, Y axle of this laser running gear moves the guide rail, and it is the orbit that supplies to remelt the laser motion on it, both ends have the running gear that can move up and down at the support in addition, this running gear linear velocity 0~100mm/s, according to presetting the grid size to make the remelting laser carry on the remelting work of next row automatically after accomplishing the coating remelting of single file.

Specifically, the enamel sealing agent is used for sealing holes of the coating, the enamel sealing agent is subjected to water-based treatment and then is uniformly sprayed on the surface of the coating, the structure of the coating after hole sealing is compact, the porosity is small, and corrosive atmosphere can be prevented from entering the coating and the matrix.

Compared with the prior art, the invention has the following advantages:

on the basis of the thermal spraying technology, the invention utilizes an X, Y double-shaft laser walking structure to carry out a layered scanning type laser remelting process on the protective coating on the surface of the four tubes of the boiler. The coating layer after the laser remelting process forms a reticular remelting line on the surface. The reticular remelting wire is metallurgically combined with the four boiler pipes, so that the problems of corrosion diffusion, coating peeling and the like are solved in the anticorrosion process of the four boiler pipe coating, the maintenance cost is reduced, and the service period is prolonged.

Drawings

Fig. 1 is a schematic diagram of a thermal spray process.

FIG. 2 is a schematic illustration of laser remelting.

Fig. 3 is a schematic diagram of sealing with a sealant.

Detailed Description

Example 1

This example uses thermal spraying powder core wire SOR of Beijing Saiyi technology limited company, remelting with semiconductor laser, and anti-corrosion coating of square grid remelted wire.

1. Surface cleaning and roughening treatment of four pipes of boiler

The surface cleaning treatment of the embodiment adopts sand blasting treatment, the sand blasting material is quartz sand with solid edges and corners and 8-16 meshes, the air pressure is greater than 0.5MPa, the angle between a spray gun and the surface of the pipe wall is 75-90 degrees, and the gun head performs sand blasting in a left-right or up-down swinging mode.

According to the standard of steel surface treatment before coating (GB/T8923.1-2011), the surface after sand blasting treatment reaches the grade Sa3 specified in the standard, namely, the attachments such as oxide skin, rust, oil stain and the like are completely removed, and the surface of the workpiece completely shows metallic luster.

2. Calculating the size and reliability of the remelted wire mesh

The power of the remelting laser, the laser walking speed and the laser spot size are calculated according to the working condition of four tubes of the boiler, the area of a single grid of the remelting line is calculated according to the requirement, and the calculated data considers the cost on the basis of considering the reliability of the coating after remelting. The laser used in the example is a semiconductor laser, the laser power is 6kW, the wavelength is 1100nm, the shape of the spot is a circular spot with the size of phi 3mm, and the size of the remelted single grid is 50mm x 50 mm. The width of the remelting line is 5mm, and the thickness of the remelting line is 0.6mm as the thickness of the coating.

3. Manufacture of thermal spraying base coating

In the embodiment, a SOR arc spraying wire of Beijing Saiyi technology Limited is adopted for manufacturing the thermal spraying coating, the diameter of the wire is 2.0mm, the supersonic speed arc spraying technology is adopted, the spraying is divided into two times, a transition layer (0.1-0.2 mm) is sprayed for the first time, and then an anti-abrasion layer (0.5-0.6 mm) is sprayed.

The spraying mode is as follows:

the operation of layering and partitioning is adopted, and each zone is 5-6 m²And after the local area spraying reaches the process design thickness, the local area spraying is shifted to other areas, so that the uniformity and the bonding force of the thickness of a spraying layer are ensured, and the phenomenon of spray leakage is prevented.

The spraying process comprises the following steps:

a. the head of the spray gun is vertical to the working surface during spraying, and the two sides of the water-spraying cold wall pipe are horizontally kept at 45 degrees and vertically reciprocate at a constant speed;

b. in order to prevent the generation of concave-convex steps, the formation of eddy current and the local abrasion, and in order to make the upper coating and the lower coating well combined when the upper zone and the lower zone work, the steps are prevented from occurring, and the top of the coating is in a smooth transition zone during spraying.

And (4) checking and accepting the coating:

the surface of the constructed spraying layer is uniform and smooth, and phenomena of pitted surface, peeling, cracking, falling and the like do not exist.

4. X, Y-shaft laser walking bracket

After the base coat is sprayed on the substrate, the step of erecting X, Y-axis laser walking support is performed, X, Y two-axis laser walking structure, generally a step-by-step moving guide rail type structure with controllable speed. The movable part is divided into two types, one is a movable laser which can move on the guide rail through setting parameters, namely scanning speed, in the example, the scanning speed of the laser is 50mm/s, and the stroke of the slide rail is 5 m. The other is an X, Y-axis moving guide rail, which is provided with a track for the movement of the remelting laser, and two ends of the guide rail are also provided with traveling devices capable of moving up and down on the bracket, so that the remelting laser finishes the movement between rows and columns, namely the linear velocity of the slide rail, in this case, the linear velocity of the slide rail is 30 mm/s.

5. Zone remelting, layer-by-layer scanning

In the embodiment, a laser partition remelting method is adopted, the coating to be remelted is uniformly partitioned according to the actual situation on site, in the embodiment, 100 remelted wires are respectively arranged on X, Y shafts according to the grid size of a remelting wire, namely 50mm x 50mm, of the coating, the remelted wires are uniformly distributed in the remelting process, and the remelted wires are connected among all the regions without broken wires.

6. Hole sealing

The coating is sealed by using the enamel sealing agent, the enamel sealing agent is subjected to water-based treatment and then is uniformly sprayed on the surface of the coating and is cured, and the coating after sealing is compact in structure and low in porosity.

Claims

1. A preparation method of a boiler four-pipe anticorrosive coating based on a laser remelting technology is characterized by comprising the following four steps: (1) cleaning and roughening the surfaces of four pipes of a boiler; (2) spraying corrosion-resistant, erosion-resistant and high-temperature-resistant alloy wire materials by adopting a thermal spraying technology to manufacture a coating; (3) utilizing an X, Y double-shaft laser walking structure to perform step-by-step scanning type laser remelting on the protective coating on the surface of the four tubes of the boiler to form latticed remelted lines; (4) and sealing the remelted coating surface with an enamel sealant.

2. The surface of the four tubes of the boiler according to claim 1 is cleaned and roughened, and the treated surface of the four tubes of the boiler is in accordance with the treatment grade in the standard of Steel surface treatment before coating (GB/T8923.1-2011).

3. The thermal spraying technique according to claim 1, wherein the thermal spraying material in a molten state is atomized by a high-velocity gas and sprayed onto the surface of the four tubes of the boiler to form a coating.

4. The laser remelting process of claim 1, wherein the anticorrosive coating of the four boiler tubes is subjected to scanning remelting step by using an X, Y biaxial laser walking structure, so that a reticular remelting line is formed on the surface of the anticorrosive coating, and the reticular remelting line is metallurgically bonded with the four boiler tubes.

5. The method for sealing the surface of the coating after remelting according to claim 1, which comprises spraying enamel powder on the surface of four tubes of a boiler uniformly after water treatment and curing.

6. The coating-remelted semiconductor laser according to claim 4, wherein the coating-remelted semiconductor laser is mounted on a moving device capable of moving on the guide rail by setting parameters, and the four-tube coating of the boiler is remelted with the surface of the substrate by using the high-energy laser beam during the movement along the guide rail to form a remelted line with the same movement track.

7. The X, Y axle moving guide of claim 2, wherein the two ends of the guide have a track for the remelting laser to move along, and the two ends of the guide have a moving device capable of moving up and down on the support, so that the remelting laser can automatically perform the remelting operation on the next row after completing the remelting of the coating on the single row.

8. The stand of claim 2, having an auxiliary rail of X, Y axle moving guide rails to provide ground support.