CN114686795A - Induction remelting-micro arc oxidation type high-temperature-resistant anti-corrosion aluminide coating for heating surface of water-cooled wall - Google Patents

Induction remelting-micro arc oxidation type high-temperature-resistant anti-corrosion aluminide coating for heating surface of water-cooled wall Download PDF

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CN114686795A
CN114686795A CN202210315066.4A CN202210315066A CN114686795A CN 114686795 A CN114686795 A CN 114686795A CN 202210315066 A CN202210315066 A CN 202210315066A CN 114686795 A CN114686795 A CN 114686795A
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coating
water
cooled wall
heating surface
aluminide
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曲作鹏
田欣利
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
    • C23C4/12—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the method of spraying
    • C23C4/131—Wire arc spraying
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
    • C23C4/04—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the coating material
    • C23C4/06—Metallic material
    • C23C4/08—Metallic material containing only metal elements
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
    • C23C4/18—After-treatment
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/026—Anodisation with spark discharge
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/04—Anodisation of aluminium or alloys based thereon

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  • Engineering & Computer Science (AREA)
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  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Engineering (AREA)
  • Electrochemistry (AREA)
  • Coating By Spraying Or Casting (AREA)

Abstract

The invention relates to an induction remelting-micro-arc oxidation type high-temperature-resistant anti-corrosion aluminide coating on a heating surface of a water-cooled wall, which is prepared by adopting aluminide high-frequency induction remelting and micro-arc oxidation coating technology and sequentially comprises an induction remelting aluminide coating covering the outer surface of a substrate of the heating surface of the water-cooled wall and an Al coating covering the outer surface of the induction remelting aluminide coating2O3And the induction remelting aluminide coating is metallurgically bonded with the matrix of the heating surface of the water-cooled wall. The coating has the comprehensive performance comparable to that of surfacing and induction fusion welding nickel-based self-melting alloy, but the high-temperature protective coating with much lower cost can adapt to the high temperature of various garbage boilers developed at high speed in ChinaThe need for protection against warm corrosion.

Description

Induction remelting-micro arc oxidation type high-temperature-resistant anti-corrosion aluminide coating for heating surface of water-cooled wall
Technical Field
The invention belongs to the field of metal surface treatment, and particularly relates to a method for preparing a high-temperature-resistant anticorrosive aluminide coating on a heating surface of a water-cooled wall by using a water-cooled wall heating surface aluminide induction remelting and micro-arc oxidation high-temperature corrosion prevention technology, and the high-temperature-resistant anticorrosive aluminide coating obtained by the method.
Background
With the accelerated implementation of the national strategy for developing new energy, the domestic waste incineration power generation industry develops rapidly in recent years. For a long time, the bottleneck problem restricting the technical development of waste incineration power generation is that the high-temperature corrosion of four pipes of a boiler is serious, and the phenomenon of pipe explosion is frequent. The corrosion resistance of the inconel625 alloy is generally improved by adopting a method for surfacing the inconel625 alloy on a heated surface of a pipe in China, and the biggest problem of surfacing the inconel625 alloy is that the dilution rate is high, the thickness of a surfacing layer is not less than 2.5mm for reducing the dilution rate, but the problems of low efficiency, high cost and the like are brought.
In 2018, Jiangsu Kehuan company adopts a composite method of flame spraying nickel-based self-fluxing alloy and high-frequency induction remelting (also called fusion welding) to prepare coatings on heating surfaces such as water-cooled walls, superheaters and the like, and has a good application effect in a high-temperature corrosion environment of boilers for years. Not only the performance and service life of the coating are not lower than those of surfacing, but also the preparation efficiency and cost are better than those of surfacing, so the development potential is very good. The structure of the water wall tube bank is shown in figure 1, the remelting process of the water wall tube bank is shown in figure 2, the external structure of the remelting coil is formed by fixedly connecting a plurality of copper tubes with closed rectangular sections, wherein the four sides connected side by side are all planes. When remelting, the coil is fixed, and the tube row is pulled by the lower transmission chain to feed forward.
At present, more than 70 percent of the methods adopted for protecting the waste incineration boiler in China are surfacing welding, about 20 percent of induction fusion welding, and the rest of thermal spraying, high-temperature coating and the like only account for less than 10 percent, namely surfacing welding and induction fusion welding occupy the domination of the market. Although the two technologies have better application effect, the situation is monotonous compared with the situation of 'making a great deal of people and deer by deer' in various technologies in developed countries. Particularly, the garbage power station in China is facing to the urgent need of transformation and high-speed development period, and the scale, quality, demand benefit and the like of the garbage power station of enterprises are caused by various factors such as the scale of cities, the developed degree of regions and the like, so that diversified characteristics are presented. Therefore, the development of a new coating technology with excellent protective performance, long service life and competitive production efficiency and preparation cost has become a new challenge for science and technology personnel in the industry.
In the industry, aluminum coating is sprayed on the surface of a metal component which is easy to corrode, which is a well-known corrosion prevention method with high quality and low price, the corrosion prevention principle is that the negative potential of aluminum and steel form a sacrificial anode protection effect so as to protect a steel substrate, and therefore the method can be distinguished as a main method with remarkable effect and low cost in a plurality of corrosion prevention methods. However, aluminum coatings are hardly used in high temperature environments above 300 ℃, mainly for three reasons: firstly, the combination of the aluminum coating and the steel substrate is mechanical combination, the porosity is high, and the aluminum coating and the steel substrate are easy to corrode and fall off in a high-temperature environment; secondly, the melting point (660 ℃) of aluminum is low, so that the aluminum is difficult to resist high-temperature oxidation and corrosion of the garbage incinerator; thirdly, because the hardness of the aluminum coating is low, the aluminum coating is difficult to bear the high-temperature erosion of the high-temperature fly ash to the surface of the aluminum coating.
Disclosure of Invention
Aiming at the three problems that the aluminum coating is difficult to use in a high-temperature environment, the invention aims to adopt the aluminide induction remelting and micro-arc oxidation coating technology to realize the application of the aluminum coating to the high-temperature corrosion protection of the heating surface of the waste boiler.
To this end, the invention provides in a first aspect an induction remelting-micro arc oxidation type water-cooled wall heating surface high temperature resistant anti-corrosion aluminide coating, which comprises an induction remelting aluminide coating covering the surface of a water-cooled wall heating surface substrate and Al covering the surface of the induction remelting aluminide coating in sequence2O3And the induction remelting aluminide coating is metallurgically bonded with the substrate of the heating surface of the water-cooled wall.
In some embodiments of the invention, the induction remelted aluminide coating has a thickness of 1 ± 0.02 mm.
In other embodiments of the present invention, the aluminum coating has a thickness of (0.3-0.5) ± 0.05 mm.
In still other embodiments of the present invention, the Al2O3The thickness of the ceramic membrane is less than or equal to 0.1 mm.
In a second aspect, the present invention provides a method for preparing a high temperature resistant anti-corrosive aluminide coating, as defined in the first aspect of the present invention, comprising:
step A, carrying out sand blasting treatment on a heating surface of a water-cooled wall to obtain the water-cooled wall with a roughened heating surface;
b, spraying an aluminide coating on the roughened heating surface of the water-cooled wall by adopting electric arc spraying to obtain the water-cooled wall with the heating surface provided with an aluminide bottom layer;
step C, carrying out high-frequency induction remelting treatment on the water-cooled wall with the aluminide bottom layer on the heating surface to obtain the water-cooled wall with the induction remelting aluminide coating on the heating surface;
d, spraying an aluminum coating on the surface of the induction remelting aluminide coating of the water-cooled wall with the induction remelting aluminide coating by using an electric arc to obtain the water-cooled wall with the heating surface provided with the aluminum coating and the induction remelting aluminide coating;
and E, longitudinally placing the water-cooled wall with the heating surface provided with the aluminum coating-induction remelting aluminide coating, and carrying out micro-arc oxidation on the aluminum coating of the heating surface of the water-cooled wall by adopting small-sized jet micro-arc oxidation equipment to obtain the high-temperature-resistant anticorrosive aluminide coating on the heating surface of the water-cooled wall.
In some embodiments of the invention, in step B, the aluminide coating has a thickness of 1 + -0.02 mm.
According to the method of the invention, in the step B, the spraying current is 80-200A, the spraying voltage is 35-80A, the air pressure is 0.6-0.9MPa, the spraying distance is 150-.
In some embodiments of the invention, in step D, the aluminum coating has a thickness of (0.3-0.5) ± 0.05 mm.
According to the method of the invention, in the step D, the spraying current is 80-200A, the spraying voltage is 35-80A, the air pressure is 0.6-0.9MPa, the spraying distance is 150-.
In some embodiments of the invention, in step D, the micro-arc oxidation thickness is less than or equal to 0.1 mm.
According to the method of the present invention, in step C, the remelting voltage is 380V, the current is 350-450A, and the moving speed of the tube row is 0.8-3 mm/s.
The invention provides a high-temperature-resistant anti-corrosion aluminide coating of an induction remelting-micro-arc oxidation type water-cooled wall heating surface and a preparation method thereofAl2O3And the induction remelting aluminide coating is metallurgically bonded with the substrate of the heating surface of the water-cooled wall. The coating has the comprehensive performance comparable to that of surfacing and induction fusion welding nickel-based self-fluxing alloy, but the high-temperature protective coating with much lower cost can meet the requirements of high-temperature corrosion protection of various garbage boilers developed at high speed in China.
Drawings
The invention will be described below with reference to the accompanying drawings.
FIG. 1 is a schematic diagram of a water wall structure.
FIG. 2 is a schematic diagram of a high-frequency induction remelting treatment process for a water-cooled wall in the prior art.
FIG. 3 is a schematic diagram of the principle of jet micro-arc oxidation.
FIG. 4 is a schematic view of a traveling spray micro-arc oxidation of a tube row aluminide coating.
The reference numerals in figures 1, 2 and 4 have the following meanings: 1 water wall (tube bank); 10 heating surface of water wall (tube row); 12 a substrate; 13 fins; 14 outer tube wall of the base; 15 inner tube wall of matrix; 21 coating the curved surface of the pipe; 22 tube root and fin coating; 60 coil support; 70 driving chain rollers; 80 high-frequency induction remelting coil (rectangular copper tube); 90 spray heads; 91 electrolyte injection; 92 an aluminide coating; 93 an electrolyte reservoir.
Detailed Description
In order that the invention may be readily understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments that are illustrated in the appended drawings. However, before the present invention is described in detail, it is to be understood that this invention is not limited to particular embodiments described. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.
Unless otherwise defined, all terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, the preferred methods and materials are now described.
Term of
The term "waterwall" as used herein is also referred to as a "waterwall," "waterwall tubes," or "waterwall tube banks" (referred to simply as tube banks). The steel pipes are usually vertically laid on the inner wall surface of the boiler wall, and are mainly used for absorbing heat emitted by flame and high-temperature flue gas in the boiler.
The terms "tube arc segment" and "tube curved surface" are used interchangeably herein and refer to the arc segment of the tube that forms the waterwall.
The term "tube top surface" as used in the present invention refers to the local surface near the highest point (end of radius perpendicular to horizontal position) of the tubes constituting the water wall.
The term "remelting" as used herein means that the flame or arc sprayed aluminide powder has been melted once and then melted once again by heating with an induction coil.
Accordingly, the term "high-frequency induction remelting treatment" as used herein means that the flame or arc sprayed aluminide powder has been melted once and then melted again by heating with a high-frequency induction coil, and is also referred to as "high-frequency induction heating treatment" herein.
The term "aluminum coating" as used herein refers to a coating formed of metallic aluminum, and more specifically, a coating formed by thermal spraying of aluminum powder.
The term "aluminide coating" as used herein is a coating formed by mixing and adding a certain proportion (< 15%) of a high-melting-point element, such as chromium, nickel, silicon, etc., mainly aluminum, in order to improve the melting point and oxidation resistance.
The terms "about," "substantially," and "primarily," when used in conjunction with a range of elements, concentrations, temperatures, or other physical or chemical properties or characteristics, as described herein, cover variations that may exist in the upper and/or lower limits of the range for the property or characteristic, including variations due to, for example, rounding, measurement, or other statistical variations. As used herein, numerical values associated with amounts, weights, and the like, are defined as all values plus or minus a certain percentage for each particular value.
II, embodiments
As mentioned above, aiming at the three problems that the aluminum coating is difficult to be used in a high-temperature environment, the invention adopts the aluminide induction remelting and micro-arc oxidation coating technology to realize the high-temperature corrosion protection of the heating surface of the waste boiler by applying the aluminum coating.
The specific implementation scheme of the invention is as follows:
(1) the inventor researches and finds that the problem of poor high-temperature oxidation resistance of the pure aluminum coating can be well solved by adopting aluminide instead of pure aluminum. The aluminide is one of three elements of Ni/Cr/Si (the content is generally lower than 15%) added into pure aluminum, so that the oxidation resistance and the hot corrosion resistance of the aluminide can be obviously improved, the stability of a coating can be improved, and the melting point (750-. These three schemes are compared: the Al-Ni coating can obviously improve the high-temperature corrosion resistance of the coating, and the combination of nickel and aluminum can generate exothermic reaction in the thermal spraying process, so that the performance of the coating is further improved; the Al-Si coating scheme has better comprehensive performance and the relative cost is the lowest; the Al-Cr coating scheme has the advantages that the high-temperature oxidation resistance is obviously improved due to the addition of Cr, and the cost performance is moderate. In short, the three schemes are respectively long and can be selected according to requirements. For example, the Al-Cr coating of the present invention preferably contains 10% chromium, which allows the melting point of the aluminide to reach 900 ℃.
(2) The inventor researches and finds that the method for remelting the aluminide coating by adopting the high-frequency induction coil can well solve the problems of low bonding strength and high porosity. The main factors influencing the induction remelting effect of the coating in the induction remelting process are the high and low of high-frequency induction heat and heat distribution, which are closely related to parameters of the material such as relative permeability, resistivity, electric field frequency, induction current, induction time and the like. The relative permeability, the resistivity and the electric field frequency belong to parameters which are inconvenient to adjust, so the influence of the change of induced current and remelting time on the induction remelting effect of the coating is mainly tested. The authors, after preliminary remelting tests, observed that no pores are visible in the surface morphology after remelting within a certain depth range, indicating that the porosity is significantly reduced and that the strength of the coating is increased due to the small recrystallized grains. By adopting a bending method test, the interface bonding strength of the coating after induction remelting is found to be remarkably improved, which indicates that the bonding mode of the coating and the substrate is changed from mechanical bonding to metallurgical bonding.
(3) The inventor researches and discovers that in addition to obviously improving the hardness of the coating by replacing pure aluminum with aluminide, the inventor designs to further adopt a rapid jet type micro-arc oxidation technology to generate a ceramic membrane on the surface of the coating so as to solve the problems of low hardness and no wear resistance of the aluminum coating; however, the inventor researches and discovers that the aluminide contains other metals, so that an alumina film is not easy to form, and pure aluminum is relatively easy to form an ideal alumina ceramic film; based on the method, the pure aluminum coating is sprayed on the surface of the aluminide induction remelting coating, on one hand, the sprayed pure aluminum coating is easy to form metallurgical bonding with the aluminide induction remelting coating; on the other hand, a rapid jet type micro-arc oxidation technology is further adopted, so that a ceramic film can be generated on the surface of the aluminum coating, and the problem that the aluminum coating is low in hardness and not wear-resistant can be well solved. As the garbage furnace is filled with a large amount of fly ash carried by high-temperature flue gas, the fly ash has an erosion effect on the heating surface of the water-cooled wall. In order to avoid the rapid thinning of the coating, the invention aims to rapidly prepare a layer of compact Al on the surface of the aluminide coating by micro-arc oxidation2O3Film, the melting point of which reaches 2000 ℃. The principle of micro-arc oxidation is that a special micro-arc oxidation power supply applies voltage on a water-cooled wall, so that metal on the surface of the water-cooled wall interacts with an electrolyte solution to form micro-arc discharge, and a ceramic membrane is formed on the surface of the metal under the action of a high-temperature electric field. Al (aluminum)2O3The thickness of the ceramic film is less than or equal to 0.1mm, and the microhardness of the film is 1000-2000 HV; the high-temperature-resistant and corrosion-resistant aluminide coating for the heating surface of the induction remelting-micro arc oxidation type water-cooled wall has the advantages of firm combination of all layers (such as between a film layer and an aluminum coating, between the aluminum coating and the induction remelting aluminide coating, and between the induction remelting aluminide coating and a substrate), compact structure, high toughness, good wear resistance, corrosion resistance, high-temperature impact resistance, electric insulation and the like. The technology has the characteristics of simple operation, easy realization of film layer function adjustment, simple process, no environmental pollution and environmental protectionAnd (3) material surface treatment technology. However, the traditional micro-arc oxidation needs to be carried out by placing the tube row in an oxidation tank, and the immersion type oxidation technology is difficult to realize for large-tube-row and special-shaped workpieces. The invention is to be realized by adopting a small scanning jet type rapid micro-arc oxidation system newly developed in recent years in China (Lupengxiang, etc. '2024 aluminum alloy surface scanning type micro-arc oxidation process research', inorganic material science report, 28 (4): 2013: 381-plus 386), and FIG. 3 is a schematic diagram of a jet type micro-arc oxidation device. When the device works, the electrolyte circulating system, the cathode spray head, the surface of the tube bank aluminide coating and the like form a micro-arc discharge loop under the action of an external voltage, the spray head can be replaced according to the shape of a workpiece, and the device is particularly suitable for micro-arc oxidation of the surface of a large and special-shaped piece such as a water wall tube bank.
The main process method mainly comprises the following steps:
(1) and spraying aluminide powder on the heating surface of the water wall tube bank by adopting a flame/electric arc spraying system, wherein the thickness of the coating is about 1 +/-0.02 mm.
(2) And starting the high-frequency induction power supply, feeding the tube bank, and penetrating through the fixed induction coil to complete quick remelting.
(3) Starting the small-sized micro-arc oxidation power supply, longitudinally arranging and fixing the tube bank, and feeding the spray head to complete the rapid micro-arc oxidation of the tube bank, as shown in fig. 4.
As can be seen from fig. 4; the nozzles of the spray head 90 spray 91 electrolyte onto the bank heat surface and form an aluminide coating 92, with excess electrolyte entering an electrolyte reservoir 93.
Specifically, the invention relates to a preparation method of a high-temperature-resistant anti-corrosion aluminide coating, which comprises the following steps:
step A, carrying out sand blasting treatment on a heating surface of a water-cooled wall to obtain the water-cooled wall with a roughened heating surface;
b, spraying an aluminide coating on the roughened heating surface of the water-cooled wall by adopting electric arc spraying to obtain the water-cooled wall with the heating surface provided with an aluminide bottom layer;
step C, carrying out high-frequency induction remelting treatment on the water-cooled wall of the water-cooled wall with the aluminide bottom layer on the heating surface to obtain the water-cooled wall with the induction remelting aluminide coating on the heating surface;
d, spraying an aluminum coating on the surface of the induction remelting aluminide coating of the water-cooled wall with the induction remelting aluminide coating by using an electric arc to obtain the water-cooled wall with the heating surface provided with the aluminum coating and the induction remelting aluminide coating;
and E, longitudinally placing the water-cooled wall with the heating surface provided with the aluminum coating-induction remelting aluminide coating, and carrying out micro-arc oxidation on the aluminum coating on the outermost layer of the heating surface of the water-cooled wall by adopting small-sized jet micro-arc oxidation equipment to obtain the induction remelting-micro-arc oxidation type high-temperature-resistant anticorrosive aluminide coating on the heating surface of the water-cooled wall.
In some embodiments of the invention, in step B, the aluminide coating has a thickness of 1 ± 0.02 mm.
According to the method of the invention, in the step B, the spraying current is 80-200A, the spraying voltage is 35-80A, the air pressure is 0.6-0.9MPa, the spraying distance is 150-.
In some embodiments of the invention, in step D, the aluminum coating has a thickness of (0.3-0.5) ± 0.05 mm.
According to the method of the invention, in the step D, the spraying current is 80-200A, the spraying voltage is 35-80A, the air pressure is 0.6-0.9MPa, the spraying distance is 150-.
In some embodiments of the present invention, in step D, the micro-arc oxidation thickness is less than or equal to 0.1mm, preferably 0.05-0.1 mm; the thickness of the ceramic film thus obtained is 0.1mm or less, preferably 0.05 to 0.1 mm.
According to the method of the present invention, in step C, the remelting voltage is 380V, the current is 350-450A, and the moving speed of the tube row is 0.8-3 mm/s.
It should be understood by those skilled in the art that the preparation method of the high temperature resistant anti-corrosion aluminide coating according to the present invention can also be understood as a preparation method of a water wall with a high temperature resistant anti-corrosion aluminide coating on a heating surface, which comprises the following steps:
(1) carrying out sand blasting treatment on the heating surface of the water-cooled wall to obtain the water-cooled wall with a roughened heating surface;
(2) spraying an aluminide coating on the roughened heating surface of the water-cooled wall by adopting electric arc spraying to obtain the water-cooled wall with the heating surface provided with an aluminide bottom layer;
(3) carrying out high-frequency induction remelting treatment on the water-cooled wall with the heating surface provided with the aluminide bottom layer to obtain the water-cooled wall with the heating surface provided with an induction remelting aluminide coating;
(4) spraying an aluminum coating on the surface of the induction remelting aluminide coating of the water-cooled wall with the induction remelting aluminide coating by using an electric arc to obtain the water-cooled wall with the heating surface provided with the aluminum coating-the induction remelting aluminide coating;
(5) longitudinally placing the water-cooled wall with the heating surface provided with the aluminum coating-induction remelting aluminide coating, and carrying out micro-arc oxidation on the aluminum coating of the heating surface of the water-cooled wall by adopting small-sized jet micro-arc oxidation equipment to obtain the induction remelting-micro-arc oxidation type high-temperature-resistant anticorrosive aluminide coating of the heating surface of the water-cooled wall.
(6) Quality control: and detecting the quality of the surface coating of the tube bank, and repairing local defects to obtain the water-cooled wall with the heating surface provided with the high-temperature-resistant anticorrosive aluminide coating.
It is easy to understand that the high-temperature resistant anti-corrosion aluminide coating prepared on the heating surface of the water-cooled wall by the method sequentially comprises an induction remelting aluminide coating covering the surface of a substrate of the heating surface of the water-cooled wall and Al covering the surface of the induction remelting aluminide coating2O3The induction remelting aluminide coating is metallurgically bonded with a matrix of the heating surface of the water-cooled wall; the high-temperature-resistant anticorrosive aluminide coating is obtained by high-frequency induction remelting and micro-arc oxidation of an aluminide bottom layer, so the high-temperature-resistant anticorrosive aluminide coating is called as an induction remelting-micro-arc oxidation type water-cooled wall heating surface high-temperature-resistant anticorrosive aluminide coating.
In some embodiments of the invention, the induction remelted aluminide coating has a thickness of 1 ± 0.02 mm.
In other embodiments of the present invention, the Al2O3The thickness of the ceramic membrane is less than or equal to 0.1mm, and preferably 0.05-0.1 mm.
It should be understood by those skilled in the art that the phrase "the induction remelting aluminide coating is metallurgically bonded to the substrate of the heating surface of the water wall" in the present invention means that the layers constituting the induction remelting-micro arc oxidation type high temperature resistant anticorrosive aluminide coating of the heating surface of the water wall are metallurgically bonded, such as between a film layer and an aluminum coating, between an aluminum coating and an induction remelting aluminide coating, and between an induction remelting aluminide coating and a substrate.
The main advantages of the invention are as follows:
(1) in terms of the protection life, compared with the coating with the thickness of about 0.5mm prepared by induction fusion welding, the coating thickness is 1 +/-0.02 mm, so the protection life can not be reduced at least; compared with the traditional surfacing, the cost of the coating is reduced by more than 70% compared with the traditional surfacing and is reduced by more than 20% compared with a fusion welding coating.
(2) The heat conductivity coefficient of the aluminide coating is very close to that of a water-cooled wall matrix, although the average heat conductivity coefficient of the coating is slightly influenced by a layer of ceramic membrane on the surface, the thickness of the ceramic membrane is less than 0.1mm, and preferably 0.05-0.1mm, so that the heat exchange of the wall of the tube is not basically influenced.
(3) The speed of remelting the aluminide coating by high-frequency induction is high, so that the crystal grains of the coating are not grown in time to be refined, and the comprehensive performance of the coating is obviously improved; and the induction heating has the aluminizing effect at the same time, so that the thickness of the diffusion layer is increased, and the bonding strength is obviously improved.
(4) Because the small-sized quick jet type micro-arc oxidation system has small volume, light weight and flexible movement, one micro-arc oxidation machine has the cost of only thousands of yuan, and can be completely provided with a plurality of devices for parallel operation, thereby improving the generation speed of the ceramic membrane on the heating surface of the water-cooled wall. Moreover, after the oxide film on the surface of the water cooling wall is thinned and even ground after the coating is used for several years, the dirt on the surface of the water cooling wall in the boiler can be cleaned by sand blasting during the blowing out period, and then the ceramic film is prepared again on site by small-sized rapid micro-arc oxidation equipment, so that the service life of the coating is further prolonged.
III, detection method
According to the invention, the porosity of the pilot frequency induction cladding coating (the nickel-based self-fluxing alloy high-frequency induction cladding coating and the nickel-based self-fluxing alloy medium-frequency induction cladding coating) on the heating surface of the water wall is monitored according to GB/T l7721-1999 (metal covering layer porosity test).
The corrosion resistance of the water wall or the coating thereof in the invention is directly detected by utilizing the actual consumption rate in production.
IV, examples
In order that the present invention may be more readily understood, the following detailed description will proceed with reference being made to examples, which are intended to be illustrative only and are not intended to limit the scope of the invention. The starting materials or components used in the present invention can be obtained commercially or by conventional methods unless otherwise specified.
Example 1:
the method for manufacturing the water-cooled wall with the heating surface provided with the high-temperature-resistant anticorrosive aluminide coating comprises the following steps:
(1) sand blasting: and carrying out sand blasting roughening treatment on the surface of the water wall tube bank by using an automatic sand blasting machine.
(2) Spraying an aluminide coating: the aluminide coating was arc sprayed to a thickness of about 1 mm. The spraying current is 80-200A, the spraying voltage is 35-80A, the air pressure is 0.6-0.9MPa, the spraying distance is 150-.
(3) Remelting: and carrying out high-frequency induction remelting on the aluminide coating. The remelting voltage is 380V, the current is 350-450A, and the moving speed of the tube row is 0.8-3/mm/s. And a special tool is adopted to strictly control the deformation of the tube row in the remelting process, as shown in figure 2.
(4) Spraying an aluminum coating: spraying an aluminum coating on the surface of the induction remelting aluminide coating of the water-cooled wall with the induction remelting aluminide coating by using an electric arc to obtain the water-cooled wall with the heating surface provided with the aluminum coating-the induction remelting aluminide coating; the aluminum coating is sprayed by electric arc spraying, and the thickness is about 0.3-0.5 mm. The spraying current is 80-200A, the spraying voltage is 35-80A, the air pressure is 0.6-0.9MPa, the spraying distance is 150-.
(5) Micro-arc oxidation: the tube bank is longitudinally placed, and micro-arc oxidation (thickness about 0.1mm) is carried out on the surface of the tube bank by adopting a small-sized jet micro-arc oxidation device, as shown in figure 4; the nozzle of the spray head 90 sprays 91 electrolyte to the heating surface of the tube bank, an aluminide coating 92 is formed, and redundant electrolyte enters an electrolyte container 93; the feeding speed of the nozzle of the shower head 90 is based on Al2O3The effect produced by the ceramic membrane is determined by tests.
(6) Quality control: and detecting the quality of the surface coating of the tube bank, and repairing local defects to obtain the water-cooled wall with the heating surface provided with the high-temperature-resistant anticorrosive aluminide coating.
The porosity of the water wall with the high-temperature resistant anti-corrosion aluminide coating on the heating surface in the embodiment is monitored according to GB/T l7721-1999 (metal covering layer porosity test), and the detection shows that the internal porosity of the high-temperature resistant anti-corrosion aluminide coating is very small (< 1.5%) and can be ignored basically.
The actual consumption rate in production is directly used for detecting the corrosion resistance of the water-cooled wall with the high-temperature-resistant anticorrosive aluminide coating on the heating surface in the embodiment, and the result is compared with the corrosion resistance of the 20G water-cooled wall tube bank with the original coating, so that the water-cooled wall with the high-temperature-resistant anticorrosive aluminide coating on the heating surface in the embodiment has good corrosion resistance, and the service life of the water-cooled wall can reach more than 8 years at medium temperature and medium pressure (450 ℃, 4 MPa).
It should be noted that the above-mentioned embodiments are only for explaining the present invention, and do not constitute any limitation to the present invention. The present invention has been described with reference to exemplary embodiments, but the words which have been used herein are words of description and illustration, rather than words of limitation. The invention can be modified, as prescribed, within the scope of the claims and without departing from the scope and spirit of the invention. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, but rather the invention extends to all other methods and applications having the same functionality.

Claims (10)

1. The induction remelting-micro arc oxidation type high-temperature-resistant anticorrosive aluminide coating for the heating surface of the water-cooled wall sequentially comprises an induction remelting aluminide coating covering the surface of a matrix of the heating surface of the water-cooled wall, an aluminum coating covering the surface of the induction remelting aluminide coating, and Al covering the surface of the aluminum coating2O3A ceramic membrane having a first major surface and a second major surface,the induction remelting aluminide coating is metallurgically bonded with a water-cooled wall heating surface substrate.
2. The high temperature resistant anti-corrosive aluminide coating of claim 1, wherein said induction remelted aluminide coating has a thickness of 1 ± 0.02mm, and said aluminum coating has a thickness of (0.3-0.5) ± 0.05 mm.
3. The high temperature resistant corrosion resistant aluminide coating of claim 1 or 2, wherein the Al is2O3The thickness of the ceramic membrane is less than or equal to 0.1 mm.
4. A method of preparing a high temperature resistant corrosion protective aluminide coating as claimed in any one of claims 1 to 3, comprising:
step A, carrying out sand blasting treatment on a heating surface of a water-cooled wall to obtain the water-cooled wall with a roughened heating surface;
b, spraying an aluminide coating on the roughened heating surface of the water-cooled wall by adopting electric arc spraying to obtain the water-cooled wall with the heating surface provided with an aluminide bottom layer;
step C, carrying out high-frequency induction remelting treatment on the water-cooled wall with the aluminide bottom layer on the heating surface to obtain the water-cooled wall with the induction remelting aluminide coating on the heating surface;
d, spraying an aluminum coating on the surface of the induction remelting aluminide coating of the water-cooled wall with the induction remelting aluminide coating by using an electric arc to obtain the water-cooled wall with the heating surface provided with the aluminum coating and the induction remelting aluminide coating;
and E, longitudinally placing the water-cooled wall with the heating surface provided with the aluminum coating-induction remelting aluminide coating, and carrying out micro-arc oxidation on the aluminum coating of the heating surface of the water-cooled wall by adopting small-sized jet micro-arc oxidation equipment to obtain the high-temperature-resistant anticorrosive aluminide coating of the heating surface of the induction remelting-micro-arc oxidation type water-cooled wall on the heating surface of the water-cooled wall.
5. The method according to claim 4, wherein in step B, the thickness of the aluminide coating is 1 ± 0.02 mm.
6. The preparation method as claimed in claim 5, wherein in step B, the spraying current is 80-200A, the spraying voltage is 35-80A, the air pressure is 0.6-0.9MPa, the spraying distance is 150-200mm, and the wire feeding speed is 1.5-3 m/min.
7. The method according to claim 4, wherein in step D, the thickness of the aluminum coating layer is (0.3-0.5) ± 0.05 mm.
8. The preparation method as claimed in claim 5, wherein in step D, the spraying current is 80-200A, the spraying voltage is 35-80A, the air pressure is 0.6-0.9MPa, the spraying distance is 150-200mm, and the wire feeding speed is 1.5-3 m/min.
9. The method according to any one of claims 4 to 8, wherein in step E, the micro-arc oxidation thickness is less than or equal to 0.1 mm.
10. The method as set forth in any one of claims 4 to 8, wherein in step C, the remelting voltage is 380V, the current is 350-450A, and the moving speed of the tube row is 0.8-3 mm/s.
CN202210315066.4A 2022-03-28 2022-03-28 Induction remelting-micro arc oxidation type high-temperature-resistant anti-corrosion aluminide coating for heating surface of water-cooled wall Pending CN114686795A (en)

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