JP2991977B2 - Conductor roll for electroplating and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductor roll for use in a continuous electroplating apparatus for a steel plate or the like, and more particularly to a conductor roll for electroplating which is excellent in both corrosion resistance and abrasion resistance, and a method for producing the same. Things. The above-described conductor roll according to the present invention is also applicable to a conductor roll used in the field of the electrochemical industry such as electrolytic cleaning using an aqueous solution or a molten salt as an electrolyte, anodization, electrolytic scale treatment, and electrolytic polishing.

[0002]

2. Description of the Related Art Conventionally, conductor rolls used in an electroplating apparatus are disclosed in (1) JP-A-58-102838, JP-A-58-133398, JP-A-62-6756, and the like. And those using materials having excellent corrosion resistance such as copper and copper alloys having excellent electrical conductivity, such as Hastelloy C alloy, and (2) JP-A-51-28511 and JP-A-58-221298. An electroplated film such as Cu, Ni-W alloy, Ni-P alloy or an electroless plated film formed on the roll surface, as seen in (3) JP-A-60-46395. After forming an electroplating film of Cu or a Cu alloy on the roll surface, a thermal spray coating of a Co-Mo-Cr alloy is formed thereon, or Ni is coated on the roll surface as disclosed in JP-A-4-346693. And its alloy, or an electroplating film of Co and its alloy,
20% by weight of Co-80 to 92% by weight WC cermet spray coating, which is provided with corrosion resistance and abrasion resistance by laminating an electroplating film and a spray coating, (4) JP-A-1-198460 As shown in JP-A-2-4952, a corrosion-resistant and abrasion-resistant material is provided on the roll surface.
A film formed by thermal spraying in an atmosphere substantially free of oxygen; (5) other rolls in which a corrosion-resistant alloy is welded as in JP-A-1-177389, JP-A-1-208406
As described in Japanese Patent Application Laid-Open Publication No. H10-209, a roll body is formed by using a corrosion-resistant and abrasion-resistant alloy powder and then subjected to HIP processing (hot isostatic pressing).

However, each of the above-mentioned prior arts has the following drawbacks and problems, and a solution is desired. Regarding the roll material, copper and its alloys have good electrical conductivity, but poor corrosion resistance and wear resistance.
In addition, Ni-based alloys with excellent corrosion resistance (for example, Hastelloy C
Alloy: 16Cr-4W-5Fe-17Mo-Ni remaining is expensive and soft (Vickers hardness around 200) and has poor abrasion resistance. Rolls with Ni or Cr electroplating on the roll surface have problems that the film thickness is thin and that the roll surface is easily corroded by an acidic plating solution. Ni and its alloys and Co and its alloys are electroplated and then abrasion-resistant hard carbide cermet (WC-Co
(Sprayed) has excellent abrasion resistance, but the acidic plating solution that has penetrated through the pores of the sprayed coating corrodes the undercoating electroplated film. There is a problem that it cannot stand.
The method of spraying in an atmosphere substantially free of oxygen has the advantage that the corrosion resistance and abrasion resistance possessed by the coating material can be exhibited relatively well because through-holes in the sprayed coating are significantly reduced. . However, there is a problem that a device that forms an atmosphere substantially free of oxygen is expensive, and the size of the device is limited, so that a film cannot be formed on a large roll. In the overlay welding of corrosion-resistant and wear-resistant alloys, there is a disadvantage that the shape of the overlay bead is easily transferred to the plated surface of the steel sheet, and the defect rate of the product increases. In addition, HIP processing rolls are known to have problems such as high production cost and difficulty in practical use.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to develop a technique which can solve the following disadvantages and problems of the above prior arts. It is an object of the present invention to overcome the above-mentioned technical problem of the conductor roll, that is, the disadvantage that either the corrosion resistance or the abrasion resistance is inferior. Another object of the present invention is to propose a method for reliably applying a low-current-resistance coating by applying a novel thermal spraying technique. That is, (1) WC, Cr ₃ C ₂ , TiC, NbC, TaC formed on the roll surface
Carbide cermet film, which is obtained by mixing carbides such as Co, Ni, and Cr (both components are baked and then pulverized), exhibits unique chemical stability and hardness against plating solution. It can be expected to exhibit performance as a wear-resistant and corrosion-resistant film. However, the recent electroplating process tends to lower the pH since a large current needs to be applied to the plating solution in order to improve productivity. Therefore, the degree of corrosion of the plating solution is very strong, and it is not possible to maintain sufficient corrosion resistance with a conventional carbide cermet sprayed coating made of a conventional single carbide. (2) In the case of a sprayed carbide cermet film formed in the air by the conventional method, since a large number of through-holes are present, the corrosion of the roll base material proceeds due to the penetration of the plating solution into the inside. As a result, the bonding force between the thermal spray coating and the base material is lost, and the coating peels off. (3) In order to prevent the corrosion phenomenon of (2) above, apply corrosion-resistant electroplating as an undercoat (for example,
JP-A-60-46395, JP-A-4-346693),
There is a method of coating a thermal spray coating on top of that, but stacking a surface treatment film with a different process increases the cost and it is difficult to form a thermal spray coating directly on the electroplating film surface, so it is performed Many defects occur in the electroplating film depending on the blasting process. Therefore, even if electroplating is performed, sufficient corrosion resistance cannot be exhibited. (4) In addition, it is not preferable to form an electroplating film as an undercoat or to spray-coat a corrosion-resistant alloy, since this results in an increase in current-carrying resistance.

[0005]

SUMMARY OF THE INVENTION The present invention solves the technical problems of a conventional conductor roll sprayed with a single carbide cermet as described above, based on the following concept. It can be solved by adoption. (1) Carbide cermet sprayed material for thermal spraying on the surface of a metal substrate roll, composite carbide powder composed of WC and Cr ₃ C ₂ and one or more metals selected from Cr, Cr-Co, Cr-Ni Uses a composite carbide cermet sprayed material having corrosion resistance and wear resistance made of an alloy. (2) Thermal spraying uses a combustion flame or explosion energy of a combustible gas as a heat source in the atmosphere, and the composite carbide cermet sprayed material powder has a flight speed in the heat source of 24 in the atmosphere.
By firing under the condition of 0 m / sec or more,
A dense thermal spray coating without pores, which serves as a path for the plating solution to enter, is formed. (3) The thermal spray coating formed by adjusting the flight speed of the thermal spray particles to 240 m / sec or more has a small current-carrying resistance because a large number of carbide particles pierce the surface of the roll base material. It will be easier. (4) The coexistence of WC with Cr ₃ C ₂ makes it possible to conveniently utilize the characteristics of both the high wear resistance of WC and the high corrosion resistance of Cr ₃ C ₂ .

That is, according to the present invention, a composite carbide composed of WC and Cr ₃ C ₂
One or two selected from alloys and Cr-Ni alloys
A conductor roll for electroplating, which is excellent in corrosion resistance and abrasion resistance, characterized in that a sprayed coating of a composite carbide cermet comprising at least one kind of metal or alloy is formed.

[0007] In the present invention, the sprayed composite carbide cermet coating preferably has a composite carbide content of 96 to 70 wt% and a metal / alloy content of 4 to 35 wt%.

In the present invention, the composite carbide in the sprayed coating of the composite carbide cermet has a WC of 98.5 to 70 wt.
% And Cr ₃ C _{2 in} a proportion of 1.5 to 35 wt%.

[0009] In the present invention, in the composite carbide,
In addition to one or more of the carbides of W ₂ C, W ₆ C _2.54 , Co ₃ W ₃ C, Co ₆ W ₆ C and Co ₂ W ₄ C generated in the manufacturing process of the thermal spray material or in the thermal spray heat source, Cr ₃ C ₂ , Cr ₂₃ C ₆ , Cr ₇ C ₃
It is preferable to contain a chromium carbide compound such as

Next, the present invention relates to a method of forming a composite carbide substantially consisting of WC and Cr ₃ C _{2 on} the surface of a metal roll,
-Combined carbide cermet sprayed material particles (3 to 60 µm) to which one or more metals or alloys selected from the group consisting of Co alloys and Cr-Ni alloys are added, are used to burn flammable gas or flammable gas Using the gas explosion energy heat source,
A method for producing a conductor roll for electroplating, which is excellent in corrosion resistance and abrasion resistance, is characterized by spraying under spraying conditions such that the flight speed of the particles is 240 m or more per second.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The action mechanism of a sprayed coating of a dense composite carbide cermet formed on the surface of a conductor roll for electroplating according to the present invention and having both excellent corrosion resistance and abrasion resistance characteristics, A method for forming a film will be described.

(1) Cermet sprayed coating of composite carbide of WC and Cr ₃ C _{2 In} general, carbide as a spray material includes TiC, ZrC, HfC,
VC, NbC, WC, BC, SiC, and the like Cr ₃ C _2. However, these carbides alone can form only a porous and poorly adherent film. Therefore, except for special cases, C
Most of them are formed as so-called carbide cermets mixed with metals such as o, Cr, and Ni. In general, carbides are hard and have excellent abrasion resistance. However, in the case of a cermet sprayed film coexisting with a metal or the like, the hardness tends to be softer than that of carbide alone. According to the experiments by the inventors, WC-Co cermet is the hardest among the films formed in the atmosphere, depending on the thermal spraying heat source and thermal spraying conditions, and has a Vickers hardness of 1000 to 1300, and Cr ₃ C ₂ -Ni. -The Cr cermet coating is in the range of 700 to 900, which is considerably lower than the hardness of each carbide alone. However, it can be said that any of the carbide cermet sprayed coatings is still higher in hardness and better in wear resistance than metal sprayed coatings and roll base materials.

[0013] However, the corrosion resistance of such carbides is also insufficient, although there is a great difference depending on the type of carbide. For example, a conventional carbide cermet comprising only one type of carbide and a metal has poor corrosion resistance. Therefore, it is difficult to make the conventional carbide cermet have both corrosion resistance and wear resistance.

Therefore, in the present invention, attention is paid not to using only one kind of carbide as a main component of the cermet but to use it as a composite carbide in which WC and Cr ₃ C ₂ coexist. did. For example, although WC alone has high hardness and excellent abrasion resistance, it has the disadvantage of poor corrosion resistance, but if Cr ₃ C ₂ can be compounded, unexpected effects that can not be obtained by itself can be obtained. Because it is obtained. In other words, the present inventors compensate for the corrosion resistance that is insufficient with WC alone by combining Cr ₃ C ₂ , while addressing the point that the wear resistance is slightly inferior with Cr ₃ C ₂ alone by combining WC. By using as a composite carbide, it was possible to form a thermal sprayed coating having excellent performance on a plating solution. In addition, as a metal component, Cr is indispensable, Cr alone or Co-Cr, Cr
By using an alloy such as -Ni, a cermet sprayed coating having both corrosion resistance and wear resistance can be formed.

The composite carbide used in the present invention is mainly composed of WC and Cr ₃ C ₂ , and the others are only unavoidable impurities. Therefore, a composite carbide cermet composed of WC and Cr ₃ C ₂ is defined as WC particles containing free carbon.
Powders such as Cr, Cr-Ni alloy and Cr-Co alloy are added to the mixture with Cr ₃ C ₂ particles and mixed, then sintered at a high temperature of 900 ° C or higher, and the sintered product is pulverized. It is obtained as a powder material for thermal spraying. Incidentally, sintering conditions and the type of the metal component, the more the amount of addition, chromium carbide to be generated is, Cr in addition to a large amount of Cr ₃ C _{2
Although 23} C ₆ , Cr ₇ C _{3 and the} like are formed, any of the carbides is suitable for the purpose of the present invention and can be used.

In this sense, in the present invention, Cr ₃ C ₂
The chromium carbide compound represented by the chemical formula of Cr ₂₃ C ₆ ,
It also includes chromium carbide having a chemical formula of Cr ₇ C ₃ .

Similarly, when Co is contained as a metal in the cermet, a compound formed by reacting with WC: Co ₃ W ₃ C or
Co ₆ W ₆ C, Co ₂ W ₄ C, etc., and WC decomposed W ₂ C, W ₆ C ₂₅
However, since these carbides are often generated during the process of producing the composite carbide of the present invention, these compounds are also within the scope of the present invention, and in fact, these compounds are formed and contained. Thus, it can be said that the effect of the present invention is generated in one aspect. The above-mentioned various carbides may be generated even in a thermal spraying heat source, but they do not affect the object of the present invention at all.

Next, the composition of the composite carbide of the present invention will be described. This composite carbide is preferably a mixture of WC: 98.5 to 70 wt% and Cr ₃ C ₂ at a ratio of 1.5 to 35 wt%, and particularly, Cr ₃ C ₂ is preferably in a range of _{3 to 20} wt%. The reason is that if the content of Cr ₃ C ₂ is less than 1.5 wt%, the corrosion resistance is poor, while if it is more than 35 wt%, the abrasion resistance tends to decrease, which is not preferable.

On the other hand, Cr, Cr-Co
Metal components such as alloys and Cr-Ni alloys are added alone or in a mixture of two or more kinds in a range of 4 to 35 wt%. In particular, 10 to 25% by weight is suitable. The reason for this is
A cermet spray coating having a metal component content of less than 4 wt% has a low porosity as well as a low mutual bonding force and adhesion of the spray particles. On the other hand, the content of this metal component is
Thermal spray coatings containing more than 35 wt% are not preferred because of their reduced hardness and poor abrasion resistance.

(2) Formation of a high-density, low-current-resistance coating by increasing the speed of flight of sprayed particles By using the above-described composite carbide cermet sprayed material, a sprayed coating for conductor rolls having both excellent corrosion resistance and abrasion resistance is formed. For forming, it is necessary to select a suitable thermal spraying method and thermal spraying conditions. In the present invention, as the thermal spraying method, a high-speed flame spraying method or an explosive thermal spraying method using a combustible gas (liquid fuel) as a heat source is suitable. In this regard, in the plasma spraying method, the WC particles in the composite carbide are strongly oxidized due to the high heat source temperature, and WC is contained in the formed thermal spray coating.
Oxides are mixed, which increases the porosity and helps the plating solution to enter the inside, which is not appropriate. In this regard, in the high-speed flame spraying method and the explosive spraying method, the temperature of the combustible gas combustion flame is in the range of 2000 to 2700 ° C. and is not higher than 3000 ° C. Therefore, the WC is not excessively heated and oxidized. This can be said to be preferable because the production amount of the product is suppressed to a practically acceptable level.

In the high-speed flame spraying method described above, it is also important to control the size of the particle diameter of the sprayed material. That is, the degree of temperature rise due to heating of spray particles is
This is because it varies depending on the particle size, that is, the particle size. The particle size of the sprayed material suitable for the purpose of the present invention is 3 ~ 60μ
m, and a particle size of 8 to 40 μm is most suitable. The reason for this is that if the particle size is smaller than 3 μm, the fluidity of the powder is poor, so that it is difficult to stably supply the powder to the spray gun, and it is not appropriate because it is easily separated from the center of the flame even in a high-speed flame. On the other hand, when the particle size is larger than 60 μm, it is not possible to heat the inside of the particles in the high-speed frame, and therefore, there is a disadvantage that such a film containing many particles becomes porous.

Next, in the present invention, the above-mentioned sprayed composite carbide cermet material adjusted to an appropriate particle size is used so that the flying speed of the particles (3 to 60 μm) in the high-speed frame is 240 m / sec or more. Then, a film is formed by spraying the material to be sprayed (roll surface). When the composite carbide cermet particles are sprayed at a high speed in this manner, a dense and high-adhesion thermal spray coating having a low electric resistance can be formed by the phenomenon described in detail below.

Many of the composite carbide cermet particles sprayed at a high speed are in a state where they are deeply pierced into the roll base material, and the cermet particles are deposited thereon to form a film. For this reason, a roll and thermal spray particles form a film with good adhesion even without a film that causes an increase in current-carrying resistance such as an undercoat.
Since both are in direct strong contact, a film having a small electric resistance is obtained. Since the high-speed spraying is performed as described above, a large number of composite carbide cermet particles reaching the roll surface are in contact with the surface (see FIG. 1). That is, while a large number of particles of the thermal spray material strike against the surface of the roll base material, some of the particles show a state in which the particles are destroyed while still pushing. Here, in the figure, 11 is a roll base material, 12 is a state in which composite carbide cermet particles are in contact with the roll base material, and 13 is a portion which is broken after the composite carbide cermet particles are in contact with and is embedded in the roll base material. Indicates a state where remains. The roll surface sprayed in such a state has almost no exposed portion of the base material, and even if a composite carbide cermet sprayed film having some through pores is formed thereon, it is directly in contact with the plating solution. There will be no contact, and good corrosion resistance will be exhibited.

The above phenomenon is closely related to the flying speed of the spray particles, that is, the kinetic energy of collision with the roll surface. When the flight speed of the particles is 240 m / sec or more, the above phenomenon is appropriately reproduced, and when the flight speed is 240 m / sec or less, the penetration of the particles is insufficient, so that even if the film can be formed, it enters the inside through the pores of the film. It is not suitable because the roll base material is corroded by the infiltrating plating solution.

FIG. 2 schematically shows a film in a state where such inappropriate thermal spraying has been performed. The thermal spray particles impinge on the surface of the roll base material 21 or 22. Since there is a discontinuous portion 24 that adheres to the roll surface in addition to the portion 23 that is recessed into the roll base material, the exposed portion 25 of the roll surface is increased.

The flying speed of the spray particles flying in the frame is obtained by measuring the time of flight over a set distance using a laser strobe, and the measured value is converted into the speed per second. is there. However, even with this method, it was difficult to measure a speed of 450 m / sec or more per second, and therefore the sprayed particle application flight speed of the present invention was specified to be 240 m / sec or more.

Even if the thickness of the sprayed composite carbide cermet coating film formed under the above-mentioned spraying conditions is 50 μm, the roll base material is not exposed, and even if some pores are found in the coating, excellent corrosion resistance is obtained. As indicated, the optimum thickness of the thermal spray coating of the present invention should be in the range of 50-300 μm. 50μ
In the case of a film thinner than m, if the surface needs to be polished after thermal spraying, it takes a long time for machining, which is not preferable. On the other hand, even if a thick film having a thickness of 300 μm or more is formed, the film characteristics are rarely deteriorated, but this is not economically advantageous.

The roll base material for forming the composite carbide cermet sprayed coating of the present invention may be Cu and its alloys, Ni-based alloys such as Hastelloy C, SUS304, SUS316
The material is not particularly limited as long as it is a relatively soft material such as stainless steel, carbon steel, or the like, to which the sprayed material can be effectively pressed.

[0029]

【Example】

Example 1 In this example, a high-speed flame spraying device was used to change the flight speed of the particles of the composite carbide cermet sprayed material while changing the thickness on an SS400 steel plate (50 mm wide × 100 mm long × 5 mm thick). After forming a 100 μm film, the film was subjected to a salt spray test (JIS Z 2371 (1988)), and the appearance of red rust was examined by observing the appearance after 96 hours. In this test, the sprayed coating with a thickness of about 100 μm always has through-pores, and the salt water penetrates into the interior through these pores. At this time, if the surface (SS 400) steel plate is exposed, it reacts with this and causes red rust. Is based on the principle of generating (1) the spray material: 74wt% WC-4wt% Cr 3 C 2 -7wt% Cr-15wt% Ni (2) flying speed of spray material: 120m / sec~450m / sec

Table 1 summarizes the results of observing the appearance of the thermal spray test specimen after 96 hours of the salt spray test. As is evident from the results, even when using the same thermal spray material, the test piece of the comparative example whose flight speed is small (No. 4, 5, 6)
It shows that a lot of red rust was generated, pores existed in the film, and the invading salt water reacted with the SS400 steel plate. In contrast, the flying speed of the thermal spray material of the present invention is increased, the test piece (No.
In 1, 2, and 3), it was found that the occurrence of red rust was hardly recognized, and that excellent corrosion resistance was exhibited. That is, in the composite carbide sprayed coating according to the present invention, even if it contains pores, the sprayed particles pierce the surface of the SS 400 steel sheet, and the effect of reducing the exposed portion of the steel sheet to such an extent that it does not hinder practical use is obtained. Is appearing.

[0031]

[Table 1]

Example 2 In this example, the corrosion resistance of a composite carbide cermet sprayed coating obtained by adding WC as a carbide and Cr ₃ C ₂ thereto was investigated. The thermal spraying method, the base material of the test piece, the film thickness and the like are the same as those in Example 1, and only the different items are shown below. (1) Thermal spray material: (Film is formed by high-speed flame spray method) a. Comparative Example 92wt% WC-8wt% Co 88wt% WC-12wt% Co 73wt% WC-7wt% Cr-20wt% Ni b. The present invention _{81.5wt% WC-1.5wt% Cr 3} C 2 -8wt% Cr-10wt% Ni 74wt% WC-4wt% Cr 3 C 2 -7wt% Cr-15wt% Ni 67wt% WC-15wt% Cr 3 C 2 -10wt% Cr-8wt% Co 53wt % WC-27wt% Cr 3 C 2 -15wt% Cr-5wt% Co Further, spray coating metallic only for reference was also prepared under the same conditions. (2) Flight speed of thermal sprayed material: 180 to 200 m / sec in the comparative example, 240 to 280 m / sec in the present invention (3) Corrosion test conditions: 1 mol of Na ₂ SO ₄ was used as a basic solution, and H ₂ SO ₄ was added to prepare a corrosion test solution adjusted to pH 1.0 and pH 12 using NaOH. The former pH 1.0 is for corrosion resistance in a strongly acidic plating solution, and the latter pH 12.0 is for an alkaline cleaning environment. Immersion conditions: The test piece was immersed in a test solution at 25 ° C. for 10 consecutive days, and the presence or absence of metal ions eluted in the solution was visually observed. That is, the dissolution of WC is based on hydrated oxides (eg, WO ₃
2H ₂ O, W ₂ O ₄・ 2H ₂ O)
Cr ₃ C ₂ can be qualitatively determined from the light green color of Cr ³⁺ ions. When it was not possible to make a visual judgment, the test solution was subjected to chemical analysis to measure the amount of metal ions.

Table 2 summarizes the amounts of the sprayed coatings eluted into the test solution. Comparative example film (No.1, 2, 3)
For, dissolution of WC was observed in both acidic and alkaline solutions. On the other hand, the elution of the composite carbide cermet film of the present invention in which carbides such as TiC, NbC, and TaC are added to WC is extremely small, and is about 10 to 30% of the comparative example.
It was found to show excellent corrosion resistance. As a metal component, it was found that Co had the lowest corrosion resistance, Ni was strong in alkalinity, but eluted slightly in an acidic solution, and Cr exhibited an average corrosion resistance to both solutions.

[0034]

[Table 2]

Example 3 In this example, the low pH of the composite carbide cermet sprayed coating was measured.
The abrasion test was performed in an environment in which a corrosive liquid was present, and the corrosion wear resistance of the film was investigated. (1) Test apparatus FIG. 3 shows an outline of a test section in a Taber tester used for a wear test of a test film. A disk 31 made of SS 400 steel plate having a diameter of 120 mm and a thickness of 5 mm was used as a base material, and various test films 32 were applied to the upper surface thereof to a thickness of 100 μm. The test coating on the disk is provided with two pairs of SiC disk-type grinding wheels 33, each of which is pressed against the coating surface with a load of 1 kg. In this state, the steel disc rotates clockwise (30 times per minute), while the grindstone itself rotates counterclockwise,
The test film is forcibly rubbed by the grindstone. In this example, a solution containing 1 mol of Na ₂ SO ₄ was adjusted to a pH of 1.0 with sulfuric acid to obtain a corrosive solution, and 50 to 60 drops of the solution were dropped per minute to the surface of the test film. And wear action coexist. The corrosion wear resistance was evaluated by measuring the number of rotations of the steel disk and the weight loss of the test film using such a test apparatus. (2) Test spray coating (spray spray method is high-speed flame spray method) 88wt% WC-12wt% Co 74wt% WC-4wt% Cr ₃ C ₂ -7wt% Cr-15wt% Ni (invention) 67wt% WC-15wt % Cr ₃ C ₂ -10wt% Cr-8wt% Co (this invention)

Table 3 compares the weight loss after rotating the steel disc 3000 times. As is clear from these results, the WC-Co cermet film (No. 1) of the comparative example shows excellent abrasion resistance under the condition without corrosive liquid, and has the least weight loss. However, it can be seen that in an environment where a pH 10 corrosive solution is dropped, the weight loss is large and the corrosion and abrasion resistance is poor. On the other hand, the coating of the present invention has a relatively large amount of wear in a dry, non-corrosive environment, but the corrosion resistance of the coating works advantageously in the presence of a corrosive liquid.
The amount of abrasion is much smaller than that of the film of the comparative example, and it can be expected to exhibit excellent corrosion resistance and abrasion resistance in an environment such as a conductor roll for electroplating.

[0037]

[Table 3]

Example 4 In this example, the following sprayed film was formed to a thickness of 200 μm on a conductor roll (has a roll made of Hastelloy C having a diameter of 200 mm and a length of 1000 mm) of an actual continuous electroplating apparatus. Was used for continuous 1000 hours to evaluate the practicality. (1) Thermal spray material (240-270m by high-speed flame spraying method)
88wt% WC-12wt% Co (comparative example) 81.5wt% WC-1.5wt% Cr ₃ C ₂ -8wt% Cr-10wt% Ni (invention) (2) Electroplating conditions Plating solution: zinc sulfate 400g / l, sodium sulfate 70g /
l pH: 1.2 to 1.3 Temperature: 50 ° C Current density: 20 A / dm ²

When the surface of the film after being used as a conductor roll for a cathode for continuous 1000 hours was observed, the film of Comparative Example was observed.
The surface of the WC-Co cermet film was roughened by the corrosive action of the plating solution, and small pits were observed, which were thought to be partially due to lack of spray particles. In contrast, the composite carbide cermet sprayed coating of the present invention has a reduced gloss over the entire surface, but lack of spray particles is not observed at all,
He was in good health.

[0040]

As described above, the composite carbide cermet of WC and Cr ₃ C ₂ is formed at a high speed by the high-speed flame spraying method.
Thermal spray coating formed on the roll surface at a speed of 240 m or more,
Since the electric resistance is low and the sprayed particles are coated on the roll surface so as to touch the roll surface, the surface exposed to the electroplating solution is eliminated, the wear resistance by WC in the composite carbide and the Cr ₃ C ₂ Demonstrate both corrosion resistance. Therefore,
Exhibits good corrosion resistance and abrasion resistance over a long period of time.
For this reason, not only is the quality of the continuous electroplated product improved, but also the productivity is improved and the cost is greatly reduced.

[Brief description of the drawings]

FIG. 1 is a view showing a state in which sprayed particles flying at a high speed are pressed against the surface of a roll, and the metal surface is covered with the particles.

FIG. 2 is a diagram schematically showing a state of spray particles that have collided with a roll surface at a flight speed of less than 240 m / sec.

FIG. 3 is a schematic view of a thermal spray coating abrasion tester.

[Explanation of symbols]

11, 21 Roll base material 12, 22 Composite carbide cermet particles pierced 13 Composite carbide cermet particles whose upper part is destroyed and lost after piercing the roll, but the lower part remains 23 Roll base Particles embedded in the material 24 Particles adhering to the roll surface 25 Exposed portion of the roll surface 31 Steel disc base material 32 Test film 33 SiC disc-type grinding wheel

Claims (5)

(57) [Claims] (1) WC and Cr ₃ C ₂ are applied on the surface of a metal roll.
Corrosion-resistant coating characterized by forming a sprayed coating of a composite carbide cermet comprising a composite carbide consisting of: and one or more metals and alloys selected from Cr, Cr-Co alloys and Cr-Ni alloys Conductor roll for electroplating with excellent wear resistance. 2. The sprayed coating of the composite carbide cermet according to claim 1, wherein the content of the composite carbide is in the range of 96 to 70 wt%, and the content of the metal / alloy is in the range of 4 to 35 wt%. Conductor roll for electroplating. 3. The composite carbide in the thermal spray coating of the composite carbide cermet has a WC of 98.5 to 70 wt% and a Cr ₃ C ₂ content of 1.85%.
The conductor roll for electroplating according to claim 1, wherein the conductor roll is constituted at a ratio of 5 to 35 wt%. 4. In the composite carbide, W ₂ C, W ₆ C produced in a process of manufacturing a thermal spray material or in a thermal spray heat source is provided.
_2.54 , Co ₃ W ₃ C, Co ₆ W ₆ C and Co ₂ W ₄ C In addition to one or more carbides, chromium carbide compounds such as Cr ₃ C ₂ , Cr ₂₃ C ₆ , Cr ₇ C ₃ The conductor roll for electroplating according to claim 1, wherein the conductor roll is contained. 5. The method according to claim 5, wherein the surface of the metal roll is substantially WC
And consists of Cr ₃ C ₂ in the composite carbides, Cr, Cr-Co alloys, Cr-
A composite carbide cermet sprayed material particle (3 to 60 μm) made by adding one or more metals or alloys selected from Ni alloys is used as a combustible gas combustion flame or a combustible gas explosion energy heat source. A method for producing a conductor roll for electroplating, which is excellent in corrosion resistance and abrasion resistance, wherein a sprayed film is formed under spraying conditions such that the flying speed of the particles is 240 m or more per second.