KR20100084310A - High-velocity oxygen fuel spraying composite powder for coating of marine engine parts and its manufacturing method - Google Patents

Abstract

PURPOSE: A high-velocity oxygen fuel spraying composite powder for coating the parts of a ship engine and a manufacturing method thereof are provided to form a fine coating layer and to improve hardness and abrasion resistance. CONSTITUTION: A high-velocity oxygen fuel spraying composite powder for coating the parts of a ship engine and a manufacturing method thereof comprise the following steps. Chrome carbide system[Cr3C2] powder, Chrome[Cr] powder and a mixture mixing with nickel powder are shattered to be in micron. Granule particles are formed by using a rotating spray dryer. The granule particles are sintered. A chrome carbide/nickel chrome system composite powder is manufactured. The mixture is composed of chrome carbide system powder of 70~80 weight%, chromium powder of 4~6 weight%, nickel of 16~24 weight%, carbon of 0.5~5 weight%, and binder of 1~% weight%. The granule particles are sintered in 900~1300°C for 10~60 minutes.

Description

High-velocity oxygen fuel spraying composite powder for coating of marine engine parts and its manufacturing method}

The present invention is a powder granulated by rotating spray method by mixing and grinding chromium carbide (Cr ₃ C ₂ ) -based powder, nickel (Ni) powder and chromium (Cr) powder for coating parts of marine engines requiring high hardness and high wear resistance. After sintering to produce chromium carbide / nickel chromium (Cr ₃ C ₂ / NiCr) -based spherical composite powder with a fine particle size of the dispersed phase, by improving the fluidity and the apparent density, the porosity is low, the hardness and abrasion resistance and corrosion resistance after coating Characterized by improved physical properties It relates to a high-speed flame spray composite powder for coating parts of a ship engine and a manufacturing method thereof.

In general, thermal spraying is one of the surface treatment technologies used to improve the wear resistance and corrosion resistance of the base metal, and is often used in limited fields such as maintenance of conventional aircraft parts, rust prevention of steel products, methods, and the like. In recent years, research on applying a thermal spraying process for the purpose of improving wear resistance to automobile parts and ship parts has been increasing through many studies on the improvement of hardware and thermal spraying powder materials and optimum thermal spraying know-how.

Such surface treatment methods include plasma thermal spraying and high-velocity oxygen fuel spraying. Among these methods, plasma thermal spraying is the most preferred method for deposition of coatings. It is a reliable technique that gives various industrial parts such as semiconductor, plant, machine parts, industrial rolls, automobiles, airplanes, etc., with characteristics such as friction resistance and abrasion resistance, wide selection of base materials, and easy design of thermal spray coatings. It has been widely used, but the surface air is mixed in the plasma jet flame during the surface treatment process, resulting in high porosity, resulting in a heterogeneous distribution, resulting in a decrease in adhesive strength. Thermal spray powder is manufactured by dissolving and crushing to make irregular particles It has a polygonal shape, the fluidity is easy to degrade and there are problems that non-uniform injection behavior is likely to occur.

Looking at the contents of the patent application technology for the plasma thermal spraying (R) plasma spraying method developed to improve the above problems, the coating that can form a coating layer having a high density of Korean Patent No. 10-0855872 A thermal spray composite, such as a method for preparing a powder for spraying and a method for preparing a plasma spray composite powder composed of metal-SiC after mixing a silicon carbide (SiC) powder of Korean Patent No. 10-0316565 with Al or NiCrAl metal powder Low pressure to improve the manufacturing method of powder or to perform plasma spraying operation under vacuum of domestic patent publication No. 1997-0010050 to improve the characteristics of plasma generated during atmospheric pressure plasma spraying and to manufacture high quality metal and ceramic coating of high quality Although patents on plasma spraying have been filed, and these patents have improved some of these problems, The plasma spraying method itself requires high energy, has low reliability of the formed film, and has a problem in that it cannot overcome fundamental limitations such as expensive equipment.

And, unlike plasma spraying, high-velocity oxygen fuel spraying (hvof, HVOF) is an innovative film treatment method developed since the late 1980s and uses a jet that generates composite powder at high pressure. As a method of forming, the physical properties of the film is very excellent, and is widely applied in various industrial fields, and various researches and developments on the development of the composite powder material and the processing conditions have been attempted.

High speed flame spray (HVOF) can achieve high temperature of 3000 ℃ by mixing fuel and oxygen and burn it, and can obtain supersonic gas velocity of Mach 5 or higher. It is a surface treatment method to obtain a spray layer having a high, low porosity and strong adhesive strength, and has the advantage of minimizing decomposition of carbide-based spray material (WC, Cr ₃ C ₂ ), which is a problem of decomposition during the spraying process. . Therefore, high-speed flame spraying is applied for the purpose of improving physical properties such as wear resistance and corrosion resistance of automobile parts and ship parts, which have been difficult to apply in the past, and thus, it is necessary to develop a composite powder for coating parts accordingly.

Therefore, the present inventors have used chromium carbide / nickel chromium (Cr ₃ C ₂ / NiCr) -based spherical composite powder for high-speed flames having properties such as high hardness, strong wear resistance, and adhesive strength so that ship engine parts can withstand long term durability. By developing the present invention can be completed.

In order to solve the problems as described above, the present invention is a high-speed flame spray (high) by chromium carbide (Cr ₃ C ₂ ) -based powder, nickel (Ni) powder and chromium (Cr) powder by mixing and grinding the granules -By manufacturing chromium carbide / nickel chromium (Cr ₃ C ₂ / NiCr) composite powder suitable for velocity oxygen fuel spraying, hvof, and HVOF, it is manufactured to be suitable for the coating of marine engine parts requiring high hardness and high wear resistance. It is an object of the present invention to provide a high speed flame spray composite powder for ship engine component coating and a method of manufacturing the same.

As described above, the high-speed flame spray composite powder according to the present invention forms particles into a spherical shape with a uniform particle size distribution to increase fluidity, so that the spray gun is not clogged during spraying, and is sprayed well, and has a high apparent density. It is possible to form a dense coating film layer, which has high mechanical properties and is composed of as small dispersed phase as possible to form a dense film structure layer to increase the hardness of the film layer, making it suitable for coating of marine engine parts requiring strong durability even in long-term use. It is characterized by the fact that it is a high-speed flame spray composite powder prepared to be.

The present invention for carrying out the above task is to grind the mixture of chromium carbide (Cr ₃ C ₂ ) -based powder, chromium (Cr) powder and nickel (Ni) powder to ultrafine and then exceeded by using a rotary spray dryer The method for producing a high speed flame spray composite powder for coating a component of a ship engine, characterized in that after forming the lip particles to sinter it to produce a chromium carbide / nickel chromium (Cr ₃ C ₂ / NiCr) composite powder. It is done.

The mixture is preferably mixed 70 to 80% by weight of chromium carbide (Cr ₃ C ₂ ) powder, 4 to 6% by weight of chromium (Cr) powder and 16 to 24% by weight of nickel (Ni) powder, The composite powder preferably has a particle size of 20 to 60 µm and an apparent density of 2.0 to 2.8 g / cm ³ .

The chromium carbide / nickel chromium (Cr ₃ C ₂ / NiCr) -based high speed flame spray composite powder according to the present invention by the above-mentioned problem solving means is a spherical particle with a uniform particle distribution, and has high fluidity, so that it can be used for high speed spraying. It is manufactured to be suitable, and it is made of dense and small dispersed phase to form a dense coating film layer, and it is suitable for coating of marine engine parts requiring strong durability by improving physical properties such as hardness, wear resistance and surface roughness. The advantage is that it is possible to extend the service life of the ship engine.

 In addition, by forming a film by using a high-speed flame spray can not only increase the reliability of the film formed by the low-spray spray energy, but also has an economic advantage because the price of equipment is low.

The present invention for achieving the above effects relates to a high-speed flame spray composite powder for parts coating of a marine engine and a method for manufacturing the same, only the parts necessary for understanding the technical configuration of the present invention will be described, the description of other parts Note that it will be omitted so as not to obscure the subject matter of the invention.

The raw material used for the high-speed flame composite powder according to the present invention is a mixture of chromium carbide (Cr ₃ C ₂ ) -based powder, nickel (Ni) powder and chromium (Cr) powder, and then chromium carbide / nickel chromium (Cr ₃ C). _It relates to a method for producing a ₂ / NiCr) -based composite powder.

Hereinafter, a method for manufacturing a high speed flame spray composite powder for coating a part of a marine engine according to the present invention is as follows.

In the present invention, the mixture of chromium chromium (Cr ₃ C ₂ ) -based powder, chromium (Cr) powder and nickel (Ni) powder is pulverized and ultrafine, and then granulated particles are formed using a rotary spray dryer and then sintered. The present invention relates to a method for manufacturing a high speed flame spray composite powder for coating a component of a marine engine, characterized in that to produce a chromium carbide / nickel chrome (Cr ₃ C ₂ / NiCr) composite powder.

In the present invention, the mixture is preferably 70 to 80% by weight of chromium carbide (Cr ₃ C ₂ ) -based powder, 4 to 6% by weight of chromium (Cr) powder and 16 to 24% by weight of nickel (Ni) powder.

When the chromium carbide (Cr ₃ C ₂ ) -based powder is formed after the thermal spraying, the chromium (Cr) powder and nickel (Ni) powder is melted dispersed in the combined nickel chromium (NiCr) matrix to give a dispersion hardening As the fine particles of, the smaller the possible particles of the dispersed phase, the denser the structure of the coating layer, the higher the hardness.

When the mixing ratio of chromium carbide (Cr ₃ C ₂ ) -based powder is less than 70% by weight, as the appropriate component ratio of the dispersed phase in the nickel chromium (NiCr) matrix decreases, the hardness of the coating formed on the base material is lowered, and thus the physical properties such as wear resistance are reduced. If the composition ratio of the chromium carbide (Cr ₃ C ₂ ) powder exceeds 80% by weight, the hardness of the coating formed on the base material increases, but the nickel chromium (NiCr) matrix component is higher than the composition ratio of the dispersed phase. There is a possibility that the strength with which the coating film adheres to the base material decreases as the appropriate component ratio of R 2 decreases.

In addition, the chromium carbide (Cr ₃ C ₂ ) powder used in the present invention preferably has a content of chromium (Cr) of 84.7 to 86.7% by weight, the rest of which is carbon (C).

In addition, chromium (Cr) powder and nickel (Ni) powder are melted after the thermal spraying to form a nickel chromium (NiCr) matrix to improve the mechanical properties of the coating, not only improve the adhesion between the base material and the coating, but also within the matrix component. Nickel (Ni) serves to improve the corrosion resistance of the film.

In addition, when the amount of chromium (Cr) powder and nickel (Ni) powder is less than 4% by weight and 16% by weight, respectively, the mechanical composition of the coating formed on the base material is decreased as the proper component ratio of the matrix is relatively smaller than that of the dispersed phase. Physical properties such as physical properties and corrosion resistance may be deteriorated. When the mixed amount of chromium (Cr) powder and nickel (Ni) powder exceeds 6% by weight and 24% by weight, respectively, the relatively dispersed phase of chromium carbide (Cr ₃₎ C ₂ ) There is a possibility that the amount of the powder to be mixed decreases the microstructure of the coating and the hardness decreases.

For reference, Figures 1a to 1c relates to a SEM photograph of the microstructure of the raw material for producing a high speed flame spray composite powder for coating parts of the marine engine according to the present invention.

FIG. 1A relates to a SEM photograph showing a microstructure state of chromium carbide (Cr ₃ C ₂ ) -based powder, FIG. 1B relates to a SEM photograph showing a microstructure state of nickel (Ni) powder, and FIG. It relates to a SEM photograph showing the state of the microstructure of the Cr) powder.

As the size of the raw material powder particles used in the present invention is shown in Figure 1a to 1c the average size of the powder particles of the chromium carbide (Cr ₃ C ₂ ) -based powder is 2.5 to 3.5 ㎛, nickel (Ni) powder is It is preferable to use what is 20-25 micrometers, and the chromium (Cr) powder is 5-10 micrometers.

In the present invention, the mixture is preferably milled for 48 to 72 hours using milling. If the milling time is less than 48 hours, the mixed powder may not be sufficiently pulverized and the powder may have a high cohesiveness. If the milling time exceeds 72 hours, the cohesiveness of the mixed powder may be low, but the productivity may decrease. There is.

For reference, Figures 2a to 2d is a SEM photograph showing the deformation process of the particles over time in the process of milling the powder of the raw material mixture for producing a high speed flame spray composite powder for coating parts of the ship engine according to the present invention It is about.

Figure 2a shows a SEM picture taken after milling the powder of the mixture for 12 hours, Figure 2b shows a SEM picture taken after milling the powder of the mixture for 24 hours, Figure 2c shows the powder of the mixture 48 2 shows a SEM photograph of the state after milling the powder of the mixture for 72 hours, in which the particle size of the composite mixture is minutely changed after 48 hours of milling time. It can be seen that it becomes uniform.

In the present invention, it is preferable to add 0.5 to 5 parts by weight of carbon with respect to 100 parts by weight of the mixture at the time of pulverization in consideration of the fact that a large amount of carbon components are separated during high-speed flame spraying.

When the amount of carbon added is less than 0.5 parts by weight, an appropriate amount of carbon is not contained in the film formed on the surface of the base material, so that the components of the dispersed phase are insufficient, which may lower the mechanical properties of the film such as hardness and wear resistance. When the added amount of carbon exceeds 5 parts by weight, excessive carbon is added to the nickel chromium (NiCr) matrix component, which may lower the mechanical properties of the coating.

As carbon added in the present invention, carbon black, activated carbon, or the like is preferably used.

In the present invention, a granulated particle is formed by rotating a mixture of ultra-fine powders using a rotary spray dryer. At this time, a binder is added to granulate the powders of the ultrafine granulated mixture, and the amount of the binder is preferably added in an amount of 1 to 5 parts by weight based on 100 parts by weight of the powder mixture.

And the granulation conditions formed in the present process is to control the granulation conditions to ensure that the inside of the particles as possible as possible to sufficiently fill the rotational speed of the rotating disk at a temperature of intake temperature 130 ~ 200 ℃ within the range of 8,000 ~ 20,000 rpm It is desirable to.

In addition, when the amount of the binder added in the present step or the granulation condition is less than the above-defined range, the inside of the granule particles is not sufficiently filled so that the speed of the particles sprayed from the gun during spraying is sufficient. Otherwise, the amount of powder particles may be small, so that a film having a uniform thickness may not be formed. If the amount of the binder or the granulation condition exceeds the range defined above, the binder is added in an excessive amount so that the apparent density of the granule particles is increased. There is a possibility that the mechanical properties of the coating may be lowered by lowering.

The binder usable in the present invention may use both a water-soluble polymer resin or a water-insoluble polymer resin, and as the water-soluble polymer, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl methyl cellulose (Hydroxypropyl methylCellulose) Alternatively, one or more selected from hydroxypropyl ethyl cellulose (Hydroxypropyl ethyl Cellulose) may be used in admixture with water, and more preferably polyvinyl alcohol. The water-insoluble polymer is preferably one in which paraffin is dissolved in an organic solvent such as alcohol or hexane.

In this invention, it is preferable to use what melt | dissolved the polymer resin by adding 1-5 weight part to 100 weight part of solvents.

Since the granulated particles prepared through the above process have low apparent density and cannot be used for thermal spraying due to the low bonding strength of the granulated ultrafine particles, the granulated particles are sintered to fill the hollow inside the granulated particles to increase the apparent density. For this purpose, only the ultrafine particles packed inside the granulated particles are sintered by applying enough heat to melt and bond. In this case, too much heat causes not only the inside of the granulated particles to melt, but also the outer surface of the granulated particles to be melted and bonded between the granulated particles, causing entanglement of the particles.

In the above sintering conditions, it is preferable to sinter for 10 to 60 minutes at 900 to 1,300 ℃. When the sintering condition is lower than the temperature range defined above, the ultrafine particles present in the granule particles may not be sufficiently melted so that the hollow density of the granule particles may remain and the apparent density may be lowered. When the temperature is higher than the temperature range defined above, the ultra-fine particles inside the granule particles are completely melted and the inside of the granule particles is filled to increase the apparent density, but the temperature is too high to melt the surface of the granule particles. There is a fear of being unsuitable for use as a thermal spray powder because they are bound together and entangled with each other.

The sintered composite powder preferably has a particle size of 20 to 60 µm and an apparent density of 2.0 to 2.8 g / cm ³ . If the composite powder deviates from the above conditions, it is not suitable for use as a composite powder for high speed flame.

As described above, the high speed flame spray composite powder prepared by the above method is formed into a sphere having a uniform particle size distribution to increase fluidity, so that the spray gun does not become clogged during spraying, and the apparent density is excellent in the durability of the coating layer, It has high physical properties such as abrasion resistance, and is composed of small disperse phase as possible. It has high hardness of the coating layer. Nickel (Ni) is included in the metal matrix, so that strong corrosion resistance property can be secured. It is characterized by being manufactured to be suitable for coating of marine engine parts.

Hereinafter, the present invention will be described in detail with reference to the following examples, but the present invention is not necessarily limited to the following examples.

1. Preparation of composite powder for high speed flame

(Example 1)

80 wt% of chromium carbide (Cr ₃ C ₂ ) -based powder having an average size of particles of 2.5 to 3.5 μm, 4 wt% of chromium (Cr) powder having an average size of particles of 5 to 10 μm, and an average size of particles of 20 to The mixture which mixed 16 weight% of 25 micrometers nickel (Ni) powders was grind | pulverized. At this time, 0.5 parts by weight of carbon black was added to 100 parts by weight of the mixed powder and pulverized. Then, the rotating powder of the rotating disk was adjusted to 20,000 rpm at a temperature of intake temperature of 130 ° C. using a rotary spray dryer to form the mixed powder into granulated particles. After the granulated mixed powder was sintered at 1,300 ° C. for 10 minutes, a chromium carbide / nickel chromium (Cr ₃ C ₂ / NiCr) -based composite powder was prepared.

1 part by weight of PVA adhesive was added to 100 parts by weight of the mixed powder in the process of granulating the mixed powder using a rotary spray dryer.

(Example 2)

70 wt% of chromium carbide (Cr ₃ C ₂ ) -based powder having an average size of particles of 2.5 to 3.5 μm, 6 wt% of chromium (Cr) powder having an average size of particles of 5 to 10 μm, and an average size of particles of 20 to The mixture which mixed 24 weight% of 25 micrometers nickel (Ni) powders was grind | pulverized. At this time, 5 parts by weight of carbon black is added to 100 parts by weight of the mixed powder, and then pulverized using a rotary spray gun to adjust the rotational speed of the rotating disk to 8,000 rpm at an intake temperature of 200 ° C. to convert the mixed powder into granulated particles. After forming, the granulated mixed powder was sintered at 900 ° C. for 60 minutes to prepare a high speed flame spray composite powder.

5 parts by weight of PVA adhesive was added to 100 parts by weight of the mixed powder in the process of granulating the mixed powder using a rotary spray dryer.

(Comparative Example 1)

A commercially available chromium carbide / nickel chromium (Cr ₃ C ₂ / NiCr) -based high speed flame spray composite powder was used as a comparison target of Examples 1 and 2.

2. Evaluation of high speed flame spray composite powder

The results of testing the apparent density (ASTM B214-86 method) and the fluidity (ASTM B213-83 method) on the samples of Examples 1, 2 and Comparative Example 1 are as shown in Table 1 below. Using samples of the thermal spraying material, a high-speed flame spray was formed under conditions of 6.3 to 6.7 gph of fuel, 1,850 to 1,950 scfh of oxygen, and spraying distance of 320 to 340 mm to form a 250 μm thick film, followed by hardness (Vickers hardness technique) and adhesion. As a result of measuring the strength (ASTM C634 method), it is shown in [Table 2] below.

Test Items Example Comparative example One 2 One Apparent density (g / cm ³ ) 2.5 2.7 2.4 Flow rate (g / sec) 1.8-1.9 1.9 ~ 2.1 1.7 ~ 1.8

According to the contents of [Table 1], Examples 1 and 2 according to the present invention was found to be superior in both the apparent density and the fluidity compared to Comparative Example 1.

Test Items Example Comparative example One 2 One Hardness (Hv) 910 870 840 Adhesive strength (psi) 9,110 9,620 9,040

According to the contents of [Table 2], Examples 1 and 2 according to the present invention was found to be excellent in both hardness and adhesive strength compared to Comparative Example 1.

3A and 3B show SEM images showing the microstructure and cross-sectional microstructure of the high speed flame spray composite powder for component coating of a marine engine according to Example 1, respectively.

As described above, the high speed flame spray composite powder for a part coating of a ship engine according to the present invention and a method of manufacturing the same have been confirmed by the above embodiments, and the present invention has been made by those skilled in the art. It will be understood that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as set forth in the claims.

Figure 1a is a SEM photograph showing the microstructure of the chromium carbide (Cr ₃ C ₂ ) raw material powder for producing a high speed flame spray composite powder for coating parts of a marine engine according to the present invention,

Figure 1b is a SEM photograph showing the microstructure of the nickel (Ni) raw material powder for producing a high speed flame spray composite powder for coating parts of a marine engine according to the present invention,

Figure 1c is a SEM photograph showing the microstructure of the chromium (Cr) raw material powder for producing a high-speed flame spray composite powder for coating parts of a marine engine according to the present invention,

Figure 2a is a SEM photograph showing the state after milling for 12 hours in the process of milling the powder of the raw material mixture for producing a high speed flame spray composite powder for coating parts of a marine engine according to the present invention,

Figure 2b is a SEM photograph showing the state after milling for 24 hours in the process of milling the powder of the raw material mixture for producing a high speed flame spray composite powder for coating parts of a marine engine according to the present invention,

Figure 2c is a SEM photograph showing the state after milling for 48 hours in the process of milling the powder of the raw material mixture for producing a high speed flame spray composite powder for coating parts of a marine engine according to the present invention,

Figure 2d is a SEM photograph showing the state after milling 72 hours in the process of milling the powder of the raw material mixture for producing a high speed flame spray composite powder for coating parts of a marine engine according to the present invention,

Figure 3a is a SEM photograph of the microstructure of the high-speed flame spray composite powder for coating parts of the marine engine according to the present invention,

Figure 3b relates to a SEM photograph of the microstructure of the cross section of the high speed flame spray composite powder for coating parts of the marine engine according to the present invention.

Claims (6)

A mixture of chromium carbide (Cr ₃ C ₂ ) -based powder, chromium (Cr) powder and nickel (Ni) powder is pulverized and ultrafine, and then granulated particles are formed using a rotary spray dryer, followed by sintering. / Nickel chromium (Cr ₃ C ₂ / NiCr) composite powder manufacturing method of the high speed flame spray composite powder for coating parts of the engine, characterized in that for producing. The method of claim 1, The mixture is 70 to 80% by weight of chromium carbide (Cr ₃ C ₂ ) -based powder, 4 to 6% by weight of chromium (Cr) powder and 16 to 24% by weight of nickel (Ni) powder of the marine engine, characterized in that Method for producing a high speed flame spray composite powder for coating parts. The method of claim 1, The mixture is a method for producing a high speed flame spray composite powder for coating parts of a ship engine, characterized in that for adding 0.5 to 5 parts by weight of carbon per 100 parts by weight of the mixture during grinding. The method of claim 1, Method for producing a high-speed flame spray composite powder for coating the parts of the ship engine, characterized in that for adding 1 to 5 parts by weight of the binder with respect to 100 parts by weight of the mixture when forming the granulated particles. The method of claim 1, The sintering conditions are a method for producing a high speed flame spray composite powder for coating parts of a ship engine, characterized in that the sintering at 900 ~ 1,300 ℃ for 10 to 60 minutes. Chromium carbide (Cr ₃ C ₂ ) -based powder, chromium (Cr) powder and nickel (Ni) powder is mixed by chromium carbide / nickel chromium (Cr ₃ C ₂ / NiCr) system prepared by the method of claims 1 to 5 A high speed flame spray composite powder for marine engine parts coating, characterized in that the spherical composite powder has a particle size of 20 to 60 µm and an apparent density of 2.0 to 2.8 g / cm ³ .

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