CN113969387A

CN113969387A - A strong, wear-resistant coating

Info

Publication number: CN113969387A
Application number: CN202011142222.9A
Authority: CN
Inventors: 戴雷
Original assignee: Shenzhen Youyi Material Technology Co ltd
Current assignee: Shenzhen Youyi Material Technology Co ltd
Priority date: 2020-10-23
Filing date: 2020-10-23
Publication date: 2022-01-25
Anticipated expiration: 2040-10-23
Also published as: CN113969387B

Abstract

The invention provides a wear-resistant coating with strong binding force, which is provided with a metal material bottom coating and a ceramic material top coating, and the binding force between the metal material bottom coating and the ceramic material top coating is improved by means of occlusion formed by a special interface structure generated between the bottom coating and the top coating. In order to achieve the above object, the present invention adopts the following technical solution, a wear-resistant coating with strong bonding force, comprising a base coat formed on a substrate, and a top coat formed on the base coat; the bottom coating is made of a metal material, and the top coating is made of a ceramic material; wherein the surface of the base coat facing the top coat has a microstructure into which the top coat can be embedded, by which microstructure a bite is formed with the top coat.

Description

Wear-resistant coating with strong binding force

Technical Field

The invention belongs to the technical field of protection of garbage incinerator equipment, and particularly relates to a wear-resistant coating with strong bonding force.

Background

In recent years, the garbage incineration industry in China is rapidly developed. By 2017, 286 seats of a domestic garbage incineration harmless treatment plant are built in China, and although the quantity of the 286 seats of the domestic garbage incineration harmless treatment plant is far from being compared with that of a domestic garbage sanitary landfill harmless treatment plant, the 286 seats of the domestic garbage incineration harmless treatment plant are replaced by the 286 seats of the domestic garbage incineration harmless treatment plant. However, the variety of the household garbage is various, the components are complex, so that a lot of problems occur in the actual operation process of the garbage incineration system, and one of the important points of the problems is how to accurately measure the temperature in the garbage incinerator so as to ensure that the garbage incineration is more sufficient and more environment-friendly. The annual discharge of solid wastes all over the world is about 80-100 hundred million t, and with the industrial development and population growth, the number is increased year by year, and as the wastes have bad influence on the environment, how to dispose the wastes becomes an important content of current environmental protection. The garbage incineration method has been rapidly developed due to the characteristics of large treatment capacity, large volume reduction and recyclability of heat energy.

In the waste incineration heat energy resource recovery, the salt content and the plastic content of the waste are high, compared with other fuels, the combustion gas product contains a large amount of corrosive gases such as hydrogen chloride and ash content, when the steam temperature of a waste incineration boiler exceeds 300 ℃, a superheater pipe made of carbon steel materials can be quickly corroded by high-temperature chlorine and chloride, so that the steam temperature of the waste incineration boiler does not exceed 300 ℃, the power generation is carried out under the low steam parameter, and the maximum power generation efficiency is about 12%. If the steam temperature can be raised to 400 ℃, the generating efficiency can reach 21 percent, which is more beneficial to the popularization and application of the generating technology of the garbage incinerator.

The domestic garbage as fuel has the characteristics of high water content, low calorific value, low components, large component change and the like, and the specific combustion working condition of the domestic garbage corrodes the metal heating surface of a boiler in the operation process, and the domestic garbage mainly has the following reasons: in the combustion process of the household garbage in the furnace, the high-concentration nitride, alkali metal, pyrosulfate, corrosion-related heavy metals and a mixture with a lower melting point are decomposed, and the comprehensive effect of the mixture mainly generates high-temperature corrosion on a metal heating surface at the position of a superheater under the condition that the temperature of high-temperature flue gas and the temperature of a metal pipe wall are higher. Wherein, the inner wall of the waste incinerator is subjected to scouring abrasion and corrosive abrasion caused by the solid particles carried in the flue gas and frequent soot blowing, and the furnace shutdown is needed for maintenance if the inner wall is slightly abraded and safety accidents are possibly caused if the inner wall is heavily abraded.

Metallic coatings are wear resistant coatings of earlier interest and applications, commonly used are coatings of the metal (Mo, Ni), carbon and low alloy steels, stainless steels and Ni-Cr alloy series. The flame spraying, electric arc spraying, plasma spraying, HVOF and explosion spraying processes are generally adopted, and the coating has the advantages of high bonding strength with a matrix, good wear resistance, corrosion resistance, good toughness and the like. But the metal coating has a short service life in a high-temperature corrosive environment.

Ceramic coatings are another widely used type of wear resistant coating, including oxides, carbides, borides, nitrides, silicides, and the like, which are crystalline or amorphous compounds of metallic and non-metallic elements. The ceramic coating has the characteristics of high melting point, high hardness, good wear resistance, corrosion resistance, high-temperature stability and the like. But the spraying ceramic coating has complex process and higher cost, the surface of the coating is easy to have cracks, and the thermal fatigue resistance is inferior to that of a metal coating; and the toughness of the coating is poor, so that the coating cannot be used for bearing larger impact load. The commonly used ceramic coatings at present comprise Al2O3, TiO2, Cr2O3, ZrO2, WC, TiC, Cr3C2, TiB2 and the like, and are generally prepared by adopting plasma spraying, flame spraying, HVOF and explosion spraying technologies.

The metal and ceramic coatings have unique excellent performance and obvious performance weakness, how to combine the respective advantageous performance of the metal and the ceramic material to realize the advantageous combination of the metal and the ceramic to prepare the composite material which has the advantages of metal strength and toughness, high temperature resistance, wear resistance, corrosion resistance and the like of the ceramic, widen the respective application range of the metal material and the ceramic material, are always popular research directions, and have wide application prospects in the industrial protection fields of aviation, aerospace, chemical industry, machinery, electric power and the like.

However, due to the difference in physical and chemical properties between metal and ceramic, such as different chemical bonding methods (metal bond/covalent bond), thermal expansion coefficient, thermal conductivity, etc., the direct combination of the two often results in the problems of weak interface bonding force and easy peeling.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides the wear-resistant coating with strong bonding force, which is provided with the metal material bottom coating and the ceramic material top coating, and the special interface structure generated between the bottom coating and the top coating forms occlusion, so that the bonding force between the metal material bottom coating and the ceramic material top coating is improved.

In order to achieve the above object, the present invention adopts the following technical solution, a wear-resistant coating with strong bonding force, comprising a base coat formed on a substrate, and a top coat formed on the base coat; the bottom coating is made of a metal material, and the top coating is made of a ceramic material; wherein the surface of the base coat facing the top coat has a microstructure into which the top coat can be embedded, by which microstructure a bite is formed with the top coat.

Further, the metal material is an alloy formed by at least two elements selected from Fe, Ti, Ni, Cr and Al, such as Ni-Cr, Ni-Cr-Ti, Ni-Cr-Al, Fe-Ti, Fe-Cr, Fe-Al alloy, etc., and other elements except Fe, Ti, Ni, Cr and Al can be contained in the alloy to enhance the performance.

Further, the ceramic material comprises hard ceramic particles and a high-temperature binder, wherein the hard ceramic particles are one or more of aluminum oxide, zirconium oxide, chromium oxide, cerium oxide, silicon carbide, silicon nitride, boron nitride and chromium carbide, and the average particle size of the hard ceramic particles is 10nm-20 μm; the high-temperature binder comprises one or more of water glass, aluminum dihydrogen phosphate, silica sol, aluminum sol and zirconium sol. In addition, the ceramic material may also contain other fillers, solvents and auxiliaries to improve the overall properties of the coating formed.

Further, the microstructure is a groove formed by laser etching or chemical mask etching, the cross section of the groove is in one or more of a square shape, a V shape, a semicircular shape and an inverted trapezoid shape, and the length of the cross section opening of the groove is more than 1.5 times of the average grain diameter of the ceramic material forming the top coating.

The formation of micro-patterns by laser etching or chemical mask etching is well known in the art and allows for the precise formation of the desired groove profile and shape, and will not be described in detail herein. However, laser etching or chemical mask etching is limited by the process, and has high requirements for equipment or environment, and a small construction space is not suitable for laser etching, and is difficult to assemble and disassemble or parts with large sizes are not suitable for chemical mask etching. To broaden the applicability of the present invention, the inventors have creatively proposed another method for forming the microstructure required by the present invention:

the pore-forming agent is mixed with the metal material, and gas generated by the pore-forming agent escapes when the bottom coating is formed, so that a microstructure is generated on the surface of the bottom coating. The method is simple to operate and can be implemented in most protection occasions theoretically.

Because the melting point of the metal material for forming the bottom coating is higher, the processes of flame spraying, electric arc spraying, plasma spraying, HVOF, explosion spraying and the like are generally adopted, and usually, the organic or inorganic pore-forming agent is decomposed early in the spraying process and cannot play a role in forming pores after the metal coating is formed. In order to meet the process requirements of the present invention, the pore-forming agent may be a metal-coated thermal decomposition material selected from carbonates, carbon materials, and the like. During the thermal spraying process, the metal used for coating plays a temporary protection role on the thermal decomposition material, and ensures that the pore-forming agent cannot be decomposed in advance and lose the function before reaching the surface of the base material. The metal used for the cladding is preferably selected to be similar to that of the primer, for example, when the primer is a Ni-Cr alloy, the cladding metal may be Ni, Cr or Ni-Cr so that when the thermally decomposable material is released, the remaining cladding metal becomes integral with the metal of the primer at elevated temperatures without substantially affecting the properties of the primer. Carbon is an ideal thermal decomposition material for the purpose of not additionally introducing impurities, and when the coated metal is melted or broken, carbon can be directly generated into carbon dioxide without any residue in the high-temperature oxidizing atmosphere of thermal spraying. The process for preparing the metal-coated carbon material is not particularly limited, and a metal shell layer can be directly deposited on the outer surface of the carbon by adopting a chemical plating mode, and other modes also comprise a hydrothermal reduction method and the like.

The metal-coated carbon material may be in the form of particles, rods or other shapes, and in order to form a microstructure having sufficiently large openings after decomposition of the carbon, the average particle size of the metal-coated carbon material should be set to 2 times or more, preferably 5 times or more, or even 10 times or more the average particle size of the ceramic particles, so that the openings of the microstructure formed when the gas generated by the carbon material is released can accommodate more ceramic particles to form occlusion. The average particle diameter of the metal-coated carbon material is, for example, 50 to 200. mu.m.

The invention also relates to a preparation method of the wear-resistant coating with strong binding force, which comprises the following steps:

(1) polishing or sandblasting the substrate to form a pretreated substrate with a rough surface;

(2) spraying a metal material containing a pore-forming agent on the surface of the pretreated base material to form a bottom coating with a microstructure;

(3) and spraying ceramic material on the base coating with the microstructure to form the top coating.

Further, the pore-forming agent in step (2) is metal-coated carbon in which the metal for coating is selected from one or more metal elements in the metal material component forming the undercoat layer.

Further, the amount of feed or carrier gas for spraying in step (2) is controlled so that the metal-coated carbon material does not prematurely decompose before reaching the surface of the substrate. The accuracy of temperature control by various thermal spray processes is not high at present, and it is only necessary to ensure that the metal-coated carbon does not prematurely decompose before reaching the surface of the substrate. Although the actual operating temperature of the thermal spray process may be above 2000 c, and the melting point of the metal material is usually only 1000 c or more, the melting of the metal material can be slowed down by increasing the amount of feed or carrier gas, etc., as long as the metal material receives a low amount of heat in a very short time of spraying. In this case, the preliminarily formed undercoat layer is not actually completely melted, and therefore, further, the preliminarily formed undercoat layer is subjected to flame or laser surface treatment to cause remelting of the surface and, more importantly, complete gas release of the metal-coated carbon, thereby producing a desired microstructure. The surface treatment also has the additional advantage that due to secondary melting, the originally formed microstructure opening can be closed to a certain degree, which is more conducive to forming an occlusion structure with higher bonding force, and in addition, when the ceramic material is subsequently sprayed, the closure of the microstructure opening can also reduce the chance of the solid particles bouncing out to a certain degree.

Further, the spraying in step (3) is cold spraying to avoid the ceramic forming melt from damaging the formed microstructure.

Compared with the prior art, the invention has the following beneficial effects:

(1) in order to overcome the problem of low binding force of the metal-ceramic composite coating in the prior art, the invention forms occlusion by means of a special interface structure generated between the bottom coating and the top coating, and improves the binding force between the metal material bottom coating and the ceramic material top coating.

(2) The pore-forming agent is mixed with the metal material, and gas generated by the pore-forming agent escapes when the bottom coating is formed, so that a microstructure is generated on the surface of the bottom coating.

(3) The carbon coated with the metal is taken as the pore-forming agent, so that the carbon can be prevented from being decomposed prematurely during spraying, a microstructure can be formed conveniently, no impurities are left, and the performance of the original metal bottom coating is not influenced.

(4) Further flame or laser remelting of the primary primer after its initial formation can completely degas the metal-coated carbon to produce the desired microstructure. The surface treatment also has the additional advantage that due to the secondary melting, the originally formed microstructure openings will be closed to a certain extent, which is more conducive to the formation of a more cohesive bite structure.

Drawings

FIG. 1 is a schematic diagram of the structure and form of the wear-resistant coating of the present invention. The reference numerals indicate the following meanings:

1: a substrate; 2: a primer layer; 3: a top coat; 4: metal coated carbon; 5: and (4) microstructure.

Detailed Description

For a further understanding of the invention, reference will now be made to the preferred embodiments of the present invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the present invention and is not intended to limit the scope of the claims which follow. All of the starting materials of the present invention, without particular limitation as to their source, may be purchased commercially or prepared according to conventional methods well known to those skilled in the art.

Referring to fig. 1a-1d, the wear resistant coating of the present invention comprises a base coat layer 2 formed over a substrate 1, and a top coat layer 3 formed over the base coat layer 2; the bottom coating 2 is made of a metal material, and the top coating 3 is made of a ceramic material; wherein the surface of the primer layer 2 facing the topcoat 3 has a microstructure 5 enabling the embedding of the topcoat 3, by means of which microstructure 5 a snap-fit is formed with the topcoat 3. The preparation process of the coating comprises the following steps:

(1) polishing or sandblasting the substrate 1 to form a pre-treated substrate 1 having a rough surface, as shown in fig. 1 a;

(2) spraying a metal material containing metal-coated carbon 4 on the surface of the pretreated substrate 1 to form a primer layer 2 having a microstructure 5, as shown in fig. 1 b;

in order to sufficiently release carbon in the metal-coated carbon 4, the melting of the metal material can be slowed down by increasing the feeding amount or the gas carrying amount, and the like, as long as the heat received by the metal material in the very short time of the injection is low. In this case, the preliminarily formed undercoat layer 2 and the metal-coated carbon 4 are not completely melted in practice, and therefore, further, the preliminarily formed undercoat layer 2 is subjected to flame or laser surface treatment to cause surface remelting, and more importantly, the metal-coated carbon is more sufficiently gassed to be released, thereby producing more desired microstructures 5. The surface treatment also has the additional advantage that due to the secondary melting, the originally formed microstructure 5 openings will be closed or adducted to some extent after being impacted by flame or laser cladding, which is more conducive to forming a more cohesive occluding structure, as shown in fig. 1 c.

(3) Ceramic material is sprayed onto the base coat 2 with the microstructure 5 to form a top coat 3, as shown in fig. 1 d. Due to the high melting point of the ceramic material, which is much higher than the melting point of the metallic material of the primer layer, the already formed microstructure 5 may be destroyed if thermal spraying is used. Therefore, the film is preferably formed by cold spraying in step (3). In order to sufficiently occupy the microstructure with the ceramic material, it is necessary to control the average grain size of the ceramic material and the average diameter of the openings of the microstructure 5 so that the average diameter of the openings of the microstructure 5 is 1.5 times or more, preferably 2 times or more the average grain size of the ceramic material.

Example 1

The method comprises the steps of taking common carbon steel as a base material, spraying metal materials Ni-Cr-Al and Ni-coated carbon powder onto the base material through HVOF to form a bottom coating, wherein the mass of the Ni-coated carbon powder accounts for 3% of that of the Ni-Cr-Al powder, the average particle size of the Ni-Cr-Al powder is 90nm, and the average particle size of the Ni-coated carbon powder is 80 microns. And spraying a ceramic material on the bottom coating by cold spraying to form a top coating, wherein the ceramic material comprises 45wt% of high-temperature binder aluminum dihydrogen phosphate, 40wt% of hard ceramic particle alumina and 15wt% of water, and the average particle size of the hard ceramic particle alumina is 80 nm. And (4) curing the surface coating at normal temperature, and then applying flame treatment to the surface for further sintering and curing. The final primer layer thickness was 200 μm and the topcoat thickness was 180 μm.

Example 2

Referring to example 1, the primer layer was also subjected to a surface flame treatment for a second reflow before the ceramic material was sprayed onto the primer layer by cold spraying to form a top coat, and the rest was the same as in example 1.

Example 3

The method comprises the steps of taking common carbon steel as a base material, spraying metal materials Ni-Cr and Ni-coated carbon powder onto the base material through HVOF to form a bottom coating, wherein the mass of the Ni-coated carbon powder accounts for 5% of that of the Ni-Cr powder, the average particle size of the Ni-Cr powder is 75nm, and the average particle size of the Ni-coated carbon powder is 50 microns. And spraying a ceramic material onto the base coat by cold spraying to form a top coat, wherein the ceramic material comprises 50wt% of high-temperature binder silica sol, 40wt% of hard ceramic particle zirconia and 10wt% of water, and the average particle size of the hard ceramic particle zirconia is 55 nm. And (4) curing the surface coating at normal temperature, and then applying flame treatment to the surface for further sintering and curing. The final primer layer thickness was 200 μm and the topcoat thickness was 180 μm.

Comparative example 1

Referring to example 1, using plain carbon steel as a substrate, a metallic material Ni-Cr-Al was sprayed on the substrate by HVOF to form a primer layer, Ni-Cr-Al powder having an average particle size of 90nm, and a ceramic material comprising 45wt% of high temperature binder aluminum dihydrogen phosphate, 40wt% of hard ceramic particle alumina having an average particle size of 80 nm, and 15wt% of water was sprayed on the primer layer by cold spray to form a top coat layer. And (4) curing the surface coating at normal temperature, and then applying flame treatment to the surface for further sintering and curing. The final primer layer thickness was 200 μm and the topcoat thickness was 180 μm.

The results are shown in Table 1:

TABLE 1

From the experimental results in table 1, it can be seen that the wear-resistant coating of the present invention has good high temperature resistance, wear resistance, thermal shock resistance, etc., and the ceramic layer and the metal layer are well bonded, and thus can be suitably used in the portions of the waste incinerator where high temperature protection is required.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A wear-resistant coating with strong bonding force, comprising an undercoat layer formed on a base material, and a topcoat layer formed on the undercoat layer; the undercoat layer is a metal material, and the surface The coating is a ceramic material; it is characterized in that the surface of the base coating facing the top coating has a microstructure capable of inlaid with the top coating, and forms an engagement with the top coating through the microstructure.

2 . The wear-resistant coating with strong bonding force according to claim 1 , wherein the metal material is an alloy formed by at least two elements selected from Fe, Ti, Ni, Cr, and Al. 3 .

3 . The wear-resistant coating with strong bonding force according to claim 1 , wherein the ceramic material comprises hard ceramic particles and a high-temperature binder, wherein the hard ceramic particles are alumina. 4 . , one or more of zirconia, chromium oxide, cerium oxide, silicon carbide, silicon nitride, boron nitride, and chromium carbide, with an average particle size of 10nm-20μm; the high-temperature binder includes water glass, phosphoric acid One or more of aluminum dihydrogen, silica sol, aluminum sol and zirconium sol.

4 . The wear-resistant coating with strong bonding force according to claim 1 , wherein the microstructure is a groove formed by laser etching or chemical mask etching, and the cross-sectional shape of the groove is square. 5 . One or more of , V-shaped, semi-circular, and inverted trapezoid.

5 . The wear-resistant coating with strong bonding force according to claim 4 , wherein the microscopic pattern is formed by laser etching or chemical mask etching. 6 .

6. the preparation method of a kind of wear-resistant coating with strong binding force according to claim 1, is characterized in that comprising the following steps:

(1) Grinding or sandblasting the substrate to form a pretreated substrate with a rough surface;

(2) Spraying a metal material containing a pore-forming agent on the surface of the pretreated substrate to form an undercoat layer with a microstructure;

(3) Spray the ceramic material on the surface of the base coat with the microstructure to form a top coat.

7. The preparation method of a wear-resistant coating with strong binding force according to claim 6, wherein the pore-forming agent is selected from metal-coated thermal decomposition materials, and the thermal decomposition materials are selected from carbonate, at least one of carbon materials.

8 . The method for preparing a wear-resistant coating with strong binding force according to claim 7 , wherein the average particle size of the metal-coated carbon material is more than twice the average particle size of the ceramic particles. 9 .

9. the preparation method of a kind of wear-resistant coating with strong bonding force according to claim 7, is characterized in that: the metal used for cladding is selected from one or more metals formed in the metal material composition of undercoating element.

10 . The method for preparing a wear-resistant coating with strong binding force according to claim 6 , wherein: in step (2), flame or laser surface treatment is performed on the preliminarily formed undercoat layer again, so that the surface is heavy. 11 . melt.