TWI490344B - Method for manufacturing roll member for molten metal bath - Google Patents

Description

Method for manufacturing roller body part for molten metal plating solution

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a method for manufacturing a roller member for use in guiding a metal material to be conveyed in a plating bath, which is disposed in a plating tank of a continuous molten metal plating apparatus, such as a molten metal bath dipping. A method for producing a roll body ("Sink Roll" or "Support Roll"), particularly for hot-dip galvanizing, hot-dip aluminizing, hot-dip aluminized aluminum alloy, hot-dip tin plating, etc. A method of manufacturing an in-slot roll used in a plating solution of a non-ferrous metal molten gold plating apparatus or a method of supporting a roll body.

As shown in Fig. 1, an in-slot roller body (2) and a supporting roller body (3) for plating a metal device such as a hot-dip galvanizing device or a molten aluminum-plating device, such as a hot-dip galvanizing device or a molten aluminum-plating device, It has been immersed in molten metal such as zinc or aluminum and is used under severe environmental conditions. Therefore, it is basically required to have the following properties: 1 When the molten metal is used, the surface of the roller body is not easily eroded; When the steel strip is in contact, the surface is not easily worn, and the initial shape accuracy can be maintained. 3 Although it is a consumable material, its life is long and the equipment cost can be suppressed. In addition, the roller body in the groove guides the steel belt in the plating tank and the direction is changed at the same time, so the steel belt is used for rolling. Therefore, the following properties are required: 4 foreign matter suspended in the plating tank ("Dross": main A particle such as an iron-zinc alloy or a mechanically bonded particle of such a particle and a gold-plated metal component has a melting point higher than that of the metal zinc, and adhesion to the surface of the steel strip causes a shape defect of the gold plating layer to be hard to adhere to. Metal-plated steel strip; 5 Generally, as shown in FIG. 2A and FIG. 2B, the outer surface of the inner roller of the groove is engraved with the above-mentioned discharge Groove (4) (4') of foreign matter. The shape of the spiral groove is required to have a metal plating surface defect (i.e., a so-called "Groove Mark") which is less likely to cause uneven metallization of the steel strip, uneven color tone, and uneven gloss.

In order to meet these requirements, conventionally, the in-slot roll body has been subjected to (a) providing a coating layer excellent in corrosion resistance against molten metal on the outer peripheral surface of the roll; and (b) improving the shape of the groove inscribed on the outer peripheral surface of the roll. In the prior art, the prior art, 1 has a tungsten-cobalt-gold (WC-Co cermet) coating with a high-speed flame (HVOF) method; 2 has proposed chemically dense the molten coating layer. The treatment method is coated with a chromium trioxide (CrO ₃ ) solution, and the chromium oxide (Cr ₂ O ₃ ) microparticles are filled and impregnated into the fine pores of the molten film by heat treatment; As shown in Fig. 2B, in addition to the conventionally known 3, the groove of the spiral groove (4) (4') is engraved on the surface of the roller body, and the surface of the roller body can be engraved on the surface of the roller body ( Processing) continuous or non-continuous grooves with a depth of 0.05~0.5mm, a width of 0.05~1.6mm and a pitch of 0.5~10mm; 5 forming a concave surface of 0.5~5mm on the circumferential surface of the roller body to avoid the transfer material and the roller body The in-slot roller body that is in direct contact with the circumferential surface.

These various techniques in the past have long-term stability of the surface shape of the roll body, prevention of adhesion of the zinc-aluminum-iron intermetallic compound, growth on the roll surface, and plating of the spiral groove for the foreign matter due to contact with the steel sheet. The reduction in color tone or uneven gloss can exert considerable effects. However, in recent years, the galvanizing quality required for automotive rust-proof steel sheets has become higher and higher, and the past improvement techniques may not be satisfactory. That is to say, the mechanical properties of the metal plated steel sheet are self-evident, and for the metallized layer of the coating base of the object of the present invention, such as metal plating defects or trace defects, etc. The quality requirements are actually more demanding.

Under such background art, the inventors investigated the surface defects of the metallized steel sheet in an attempt to improve the quality of the metallized surface, because the contact surface of the steel sheet and the roller body, in particular, the extremely small shape of the roll surface Defects (face, line, point) cause. Further, with respect to these shape defects, in addition to the shape defects of the surface of the film itself, components such as foreign matter adhered to the grooves on the surface of the film were investigated in particular. Further, it has been found that these plating solution components are fine iron-aluminum or iron-aluminum-zinc intermetallic compounds.

As for the prior art known as a tungsten carbide-cobalt-gold alloy spray film, the protection of the roll base material should be effective because of the material having molten metal resistance. However, in the above-mentioned molten film, a small amount of a non-homogeneous metal cobalt phase was observed by X-ray diffraction. This cobalt phase has affinity with molten zinc-aluminum and becomes the core of the iron-aluminum or iron-aluminum-zinc intermetallic compound, promoting adhesion. In addition, the effect of chromium oxide (Cr ₂ O ₃ ), which is known in the prior art, particularly in the grain boundary layer of the surface of the roll body in contact with the molten zinc-aluminum, coexists in the field of relatively microscopic fields. The chromium oxide (Cr ₂ O ₃ ) is reduced to form metallic chromium. Therefore, in the plating solution, in the same molten aluminum galvanizing bath, the thermodynamic chromium oxide (Cr ₂ O ₃ ) becomes unstable and accelerates the deterioration of the film, and also The adhesion of the intermetallic compound described above is promoted.

As explained above, the existing method, although the surface of the base material is protected by Macro, actually does not inhibit iron-aluminum or iron-aluminum-zinc metal from the microscopic point of view. Adhesion and growth of inter-compounds.

In view of the fact that the above-mentioned microscopic viewpoint has not been able to suppress the adhesion and growth of iron-aluminum or iron-aluminum-zinc intermetallic compounds, the object of the present invention is to provide metal plating which is prevented from being caused by the surface properties of the roller body. A method for manufacturing an effective roll member of a surface defect problem, in particular, a method for producing a surface film. Another object of the present invention is to provide a method for forming a surface film of a roll body in which metal-plated foreign matter is less likely to adhere to the roll surface and is easily peeled off.

In order to achieve the above object, the present invention reviews the microstructure of the surface of a tungsten carbide-cobalt molten film formed on the surface of an existing roll body to remove iron-aluminum or iron-aluminum-zinc metal which is generally referred to as a foreign matter in a broad sense. The adhesion of the intermetallic compound to the surface of the roll body is disadvantageous. As a result of intensive research by the inventors, the invention based on the following points was conceived.

The invention provides a tungsten carbide-cobalt molten film formed by spraying a powder of tungsten carbide-cobalt porcelain gold on the surface of a steel base material, and then coating on the surface of the tungsten carbide-cobalt molten film. a foreign matter obtained by containing an aqueous solution of chromium oxide and a nitride, and then calcined by heating, thereby providing a sintering mixture in the above-mentioned tungsten carbide-cobalt-gold alloy molten film and small pores existing in the vicinity of the surface layer of the film. A method of manufacturing a roll body material for a molten metal plating bath characterized by being covered and filled.

In addition, the present invention provides a tungsten carbide-metal boride-cobalt-sprayed film coated on a surface of a steel base material to form a tungsten carbide-metal boride-cobalt-based porcelain gold powder, followed by tungsten carbide-metal boron a surface of the compound-cobalt-gold alloy spray film coated with a metal oxide having a chemical affinity with oxygen than chromium or a mixture of the oxide and the nitride and a suspension of the aqueous metal salt solution (Slurry) Firing, in the aforementioned tungsten carbide-metal boride a cobalt-based porcelain gold-soldered film and a small pore existing in the vicinity of the surface layer of the film, wherein the fired oxide or the sintered mixture of the oxide and the nitride is coated and filled with molten metal plating A method of manufacturing a roller body member for a bath plating solution.

Further, in the present invention, the boride described above is derived from titanium boride (TiB ₂ ), zirconium boride (ZrB ₂ ), hafnium boride (HfB ₂ ), vanadium boride (VB ₂ ), or lanthanum boride ( One or more selected from the group consisting of TaB ₂ ), NbB ₂ , NiB ₂ , W ₂ B ₅ or WB, and CrB ₂ The foregoing oxides are derived from neodymium (Nb), manganese (Mn), cerium (Si), zirconium (Zr), magnesium (Mg), calcium (Ca), titanium (Ti), aluminum (Al), and antimony ( Y) or the like is selected from the group consisting of oxides selected from the group consisting of titanium nitride (TiN), zirconium nitride (ZrN), vanadium nitride (VN), tantalum nitride ( TaN), aluminum nitride (AlN), boron nitride (BN), tantalum nitride (NbN), tantalum nitride (Si ₃ N ₄ ), and hafnium oxide-aluminum nitride (SiO ₂ -AlN) Select more than one of the groups.

Furthermore, in the present invention, the tungsten carbide-metal boride-cobalt-gold alloy powder is first calcined by a mixed powder of tungsten carbide and cobalt to form a metal compound or a tungsten carbide composite compound therebetween. Then, a tungsten metal-cobalt intermetallic compound or the tungsten carbide composite compound is added with a mixed metal boride, and a binder having a particle size of 5 to 50 μm is formed through a binder.

Further, the present invention is particularly effective in the use of a roll member for a molten metal galvanizing bath plating solution containing Al in a plating solution component.

As for the molten metal plating tank, particularly a material which is durable to the molten zinc-aluminum alloy, carbides, oxides, nitrides, borides and the like are most widely known. As far as the inventor's research is concerned, it is of course desirable to have a mixture of these materials in the roll material for the molten metal plating tank, such as a molten tungsten carbide-metal boride-cobalt type porcelain gold, etc., but only Still not enough, it is necessary to make the surface treatment of the pore sealing of the molten film. That is to say, in the method for sealing the pores of the present invention, it is necessary to coat and fill a metal oxide having a more affinity with oxygen than chromium, or a mixture of the oxide and the nitride, which will be described in detail below. . Further, for the method of sealing the tungsten carbide-cobalt-gold alloy molten film coated on the surface of the steel substrate, a mixture of chromium oxide and nitride can be used, which will be described in detail later.

Referring to Fig. 3, a standard generation free energy temperature diagram of a representative of the foregoing metal oxide used in the present invention is disclosed.

Further, regarding the molten metallization treatment, for example, in the galvanization-aluminum alloy, it is known that molten aluminum is an extremely active component, and when it coexists with other metal oxides, it gradually reduces other metal oxides to change its metal state. It will itself become more stable alumina (Al ₂ O ₃ ). This phenomenon is also seen in the relationship between the standard free energy of oxide formation and temperature in metal thermodynamics. That is to say, according to this relationship, for example, chromium oxide (Cr ₂ O ₃ ) which is known as a tungsten carbide-cobalt molten film is thermodynamically superior to alumina (Al in the case of metal plating temperature (460 ° C). ₂ O ₃ ) is more unstable, and in the case of balance, there is a reduction in coexistence with metallic aluminum, and there is a possibility of generating metallic chromium.

Therefore, in this context, the inventor firstly replaces tungsten carbide-cobalt porcelain gold with the premise of using tungsten carbide-metal boride-cobalt-based porcelain gold which is not easily wet-impregnated with molten metal and has heat resistance. As a sealing agent or a sealing material on the molten film, a metal oxide which is more thermally stable than chromium oxide (Cr ₂ O ₃ ) is discussed. According to the study by the inventors, the so-called metal oxide which is thermodynamically more stable than chromium oxide (Cr ₂ O ₃ ), and the metal component formed by the reduction of molten aluminum, suggests that it and the plating composition The affinity between them has an effect of preventing adhesion and growth of iron-aluminum and iron-aluminum-zinc metal compounds on the surface of the roll in the bath which is immersed in the plating solution.

The metal oxide layer is coated on the tungsten carbide-metal boride-cobalt-based molten film with the above metal ion-containing aqueous solution and the mixed suspension of the aqueous solution and the nitride to cause water and reaction, and hydrolyzed, After the condensation polymerization reaction, it is further treated by a heat baking method, and is formed by permeating the pores of the surface of the molten film and the pores of the surface layer of the film. In addition, those which are more susceptible to oxidation than chromium to form metal oxides include: niobium (Nb), manganese (Mn), antimony (Si), zirconium (Zr), magnesium (Mg), calcium (Ca), titanium (Ti), Aluminum (Al) and bismuth (Y). That is, in the present invention, a metal salt such as a metal salt aqueous solution or a metal alkoxide using these metals as a substrate is used as an aggregate, and the prepared suspension is mixed and adjusted, and the suspension is applied to the suspension. After the above-mentioned molten film is dried on the same, it is formed by a firing method.

Table 1 φ × 300 mml on carbon steel surfaces 90 μ m thickness 25mm coated tungsten carbide - metal boride - cobalt cermet thermal sprayed coating, then spraying this coating film surface of each of chromic acid Aqueous solution (comparative case number 5), aqueous solution of zirconium nitrate (suitable for case number 1), aqueous solution of lanthanum nitrate (suitable for case number 2), magnesium nitrate (suitable for case number 3), aluminum nitrate (not case number 4), followed by 550 After burning at °C for 1 hour, the device was placed in a bath of zinc-0.1% aluminum and 460 °C plating bath, and immersed for 300 hours to observe the crystalline iron-aluminum or iron-aluminum-zinc metal on the surface. The degree of adhesion of the intermetallic compound. As shown in the table, there is no obvious adhesion or accumulation of intermetallic compounds in the description of each test material; these test materials were sliced, and the presence of aluminum on the surface of the film was quantitatively analyzed by SEM X-ray image. For comparison case (No. 5) Apparently, the appropriate case (numbers 1, 2, 3) of the present invention is advantageous. This can be attributed to the difference in the reduction reaction caused by the above metal oxide impregnated with the molten metal on the tungsten carbide-metal boride-cobalt spray film. That is to say, microscopically, in any case, there is a dissolution of the metal component in the molten film, but in the case of Comparative Case 5, the thermodynamic reactivity of the chromium oxide is not good, and the generated metallic chromium provides The growth site of an iron-aluminum intermetallic compound causes an increase in the adhesion of the compound.

Further, the present invention is not limited to the above metal oxides, and as described above, a mixture of these oxides and nitrides may be used; that is, a sealing agent for a tungsten carbide-metal boride-cobalt-based spray film. As the covering material and the sealing material, a mixture of the above metal oxide and nitride can also be used. According to the investigation by the inventors, these nitrides have a large contact angle of 90 ° C or more for the molten zinc-aluminum alloy, and have characteristics that are extremely difficult to wet. Moreover, the thermodynamic reactivity with the coexisting molten aluminum is low and stable compared to the chromium oxide. For the nitride, titanium nitride (TiN), zirconium nitride (ZrN), vanadium nitride (VN), tantalum nitride (TaN), aluminum nitride (AlN), boron nitride (BN), Niobium nitride (NbN), tantalum nitride (Si ₃ N ₄ ), and hafnium oxide-aluminum nitride (SiO ₂ -AlN) (Sialon).

On the other hand, the metal boride in the molten film coated on the surface of the base material can be suitably used for titanium boride (TiB ₂ ), zirconium boride (ZrB ₂ ), hafnium boride (HfB ₂ ), boride. Vanadium (VB ₂ ), tantalum boride (TaB ₂ ), niobium boride (NbB ₂ ), nickel boride (NiB ₂ ), tungsten boride (W ₂ B ₅ or WB), and chromium boride (CrB ₂ ) Wait. These metal borides are added to a ratio of 5 to 60% by weight. The reason is that when the amount of boride is less than 5% by weight, the boride hardly exhibits wetting characteristics for molten zinc, and on the other hand, even if it is more than 60% by weight, the characteristics are not particularly improved.

Further, cobalt (Co) mixed in the above film is added in the range of 5 to 20% by weight. The reason is that when the content is less than 5%, the bonding strength between the tungsten carbide and the metal boride particles constituting the molten film is weakened, and the crack reduction and the adhesion of the steel base material occur. On the other hand, when it is more than 20% by weight, in addition to the diffusion reaction inside the film of the molten metal, the adhesion phenomenon of the foreign matter component increases.

Next, a description will be given of a related manufacturing method of the present invention. First, adjusting the suspended matter to be coated or sprayed on the surface of the base material, the suspended matter is obtained by mixing the above metal oxide and nitride powder with an aqueous solution of a metal salt to adjust an average particle size of 0.5 to 1.0 μm , and then Depending on the necessity, the same powder is added as a suspension (10~35wt%) of the required concentration of the aggregate. The suspension is coated with tungsten carbide-metal boron in a steel base material by dipping, coating or spraying. On the compound-cobalt spray film. Then, it is heated and fired at a temperature of 550±10° C., whereby the fine particles are coated on the molten film, and the micropores in the vicinity of the surface layer are also infiltrated and sealed, and the present invention will be further hereinafter described. The method is described in detail.

Formation of a lower-layer porcelain gold-plated film: a steel base material (roller base material) that needs to be subjected to a necessary surface treatment such as degreasing, washing, roughening, etc., coated with a tungsten carbide-metal boride-cobalt system Porcelain gold. Here, the porcelain gold powder used for the spraying is a mixed powder of raw material powders such as tungsten carbide, metal boride, and cobalt. In the mixed powder, initially, the tungsten carbide and the cobalt are mixed and the intermetallic compound between the two is firstly calcined, for example, cobalt tungsten carbide (Co ₃ W ₃ C) or tungsten carbide (WC). W ₆ C _2.54 , W ₂ C, etc. generated by partial decomposition. Next, the metal boride is directly mixed in the tungsten carbide-cobalt intermetallic compound powder, or mixed with an organic binder to obtain a powder having an average particle size of 5 to 50 μm , and the method can be uniformly mixed. Metal cobalt, titanium boride (TiB ₂ ), nickel boride (NiB ₂ ), and chromium boride (CrB ₂ ) are significantly different from the specific gravity of tungsten carbide.

The spraying method of the present invention can be any one of a plasma spraying method, a high-speed flame (HVOF) spraying method, and an explosive spraying method, and is not particularly limited.

Table 2 shows the use of tungsten carbide (WC)-20wt% chromium boride (CrB ₂ )-15wt% tungsten boride (W ₂ B ₅ )-12wt% cobalt (Co) porcelain gold spray film with a thickness of 90 μ m Covering 25mm φ × 300 mml carbon steel, these are compared with the case of Comparative Example 3 using chromic acid aqueous solution, and the appropriate case 1 aqueous solution of zirconium nitrate and boron nitride (BN), suitable case 2 aqueous solution of zirconium nitrate plus A suspension obtained by mixing cerium nitride (Si ₃ N ₄ ) was applied and impregnated, and fired at 550 ° C for 1 hour as a test material. Next, these test materials were placed in the end of the roller in the bath of zinc-0.1% aluminum at 460 ° C, and after 300 hours of flow immersion, the surface of the iron-aluminum or iron-aluminum was observed. The adhesion of zinc metal compounds. As a result, the present invention is suitable for the case number 1 as in the case of the metal oxide impregnation described above, and the level 2 is superior to the comparative case number 3, and it is considered that the adhesion amount of the intermetallic compound is small.

Further, the use of an aqueous metal salt solution, for example, a zirconium compound, is not limited to only zirconium nitrate (Zr(NO ₃ ) ₄ ), and zirconium hydroxide (Zr(OH) ₄ ‧ nH ₂ O) or zirconium sulfate hydrate ( Zr(SO ₄ ) ₂ ‧4H ₂ O), zirconium carbonate (Zr(CO ₃ ) ₂ ), zirconium chloride (ZrCl ₄ ), or a metal salt aqueous solution of other compositions of the present invention, Nb, manganese Nitrate, sulfate, carbonate, hydroxide, etc. of (Mn), cerium (Si), magnesium (Mg), calcium (Ca), titanium (Ti), aluminum (Al), and cerium (Y).

Further, the present inventors focused on solving the problems of the prior art to achieve the object of the present invention. Another aspect relates to: except that the use of chromium oxide (Cr ₂ O ₃ ) is regarded as tungsten carbide-metal boride-cobalt porcelain. The basics of the sealing agent for the gold-sprayed film are, on the one hand, a nitride which is thermodynamically more stable than chromium oxide (Cr ₂ O ₃ ) in order to serve as a finishing material for this disadvantage. Moreover, these mixtures are also prepared as the above-mentioned sealing agent. That is to say, in the study by the inventors, the nitride is a compound which is relatively difficult to wet-impregnate at a contact angle of 90 degrees or more with respect to the molten metal zinc-aluminum alloy. Moreover, this nitride has a lower thermodynamic reactivity with molten aluminum than chromium oxide. Therefore, when such nitride particles are present and close to chromium oxide (Cr ₂ O ₃ ) particles, chromium oxide (Cr ₂ O ₃ ) is reduced by molten aluminum in the plating solution to form metallic chromium; however, even so, The probability of contact of the minute metal chromium portion with the plating solution is also low. As a result, in the field of micro-vision, the metal chromium formed by the reduction of molten aluminum exhibits its affinity with the plating liquid component, and it can be said that it produces iron-aluminum and iron which prevent the surface of the roller body immersed in the plating solution. - Adhesion and growth of aluminum-zinc intermetallic compounds.

The method provided in the present invention is a suspension of a mixture of an aqueous solution of chromium oxide (CrO ₃ ) and a nitride coated on a tungsten carbide-cobalt molten film, which undergoes water and reaction, hydrolyzation, and condensation polymerization. It is treated by a calcination method, and is coated on the surface of the mixed calcined particles of the chromium oxide (Cr ₂ O ₃ ) and the nitride, and the pores are passed through the pores of the surface layer of the film to impregnate the pores.

In the present invention, ammonium chromate ((NH ₄ ) 2CrO ₄ ) or ammonium dichromate (NH ₄ ) 2Cr ₂ O ₇ or the like may be used alone or in combination with the aqueous solution of chromic acid (CrO ₃ ). These aqueous solutions of chromic acid and chromate compounds are decomposed by calcination by heating, and are characterized by the production of fine chromium oxide (Cr ₂ O ₃ ) particles in the final product. Therefore, if the final product is a chromium oxide (Cr ₂ O ₃ ) compound, chromium chloride (CrCl ₂ ), chromium sulfate (CrSO ₄ ), chromium carbonate (CrCO ₃ ), or chromium hydroxide (Cr (OH) can be used. ) ₃ ) Wait. Therefore, in the present invention, various chromium compounds of this type are collectively referred to as "chromium oxide-containing mixtures" for convenience of writing.

In the present invention, the chromic acid aqueous solution, that is, the nitride used in combination with the chromic acid is titanium nitride (TiN), zirconium nitride (ZrN), vanadium nitride (VN), tantalum nitride (TaN). ), aluminum nitride (AlN), boron nitride (BN), tantalum nitride (NbN), tantalum nitride (Si ₃ N ₄ ), and hafnium oxide-aluminum nitride (SiO ₂ -AlN) (Sialon) More than one of the selected groups is selected.

Further, the mixed suspension of the chromic acid aqueous solution and the nitride is prepared by mixing and mixing the above-mentioned nitride powder having an average particle size of 0.5 to 1.0 μm with an aqueous chromic acid solution. In addition, chromium oxide powder may be added as an aggregate as necessary. The suspended matter thus adjusted is coated on the tungsten carbide-cobalt molten film covered on the surface of the steel base material by coating or spraying. Then, it is heated and fired at a temperature of 550 to 700 ° C, and the fired fine particles are coated on the molten film, and are also invaded and impregnated into minute pores in the vicinity of the surface layer.

Table 3 is a 25 mm φ × 300 mml carbon steel coated with a tungsten carbide-cobalt-gold alloy molten film at a thickness of 90 μm. These are a mixed suspension of 1 chromic acid aqueous solution and cerium nitride (Si3N4), 2 aqueous chromic acid and nitrogen. a mixed suspension of boron (BN), a mixed suspension of 3 chromic acid aqueous solution and aluminum nitride (AlN), and a comparative example 4 only a chromic acid aqueous solution, which are coated and impregnated after coating; The material fired at 550 ° C for 1 hour was used as a test material. And these materials were installed in the end of the roller in the zinc-0.1% aluminum 460 ° C plating solution, after 300 hours of flow impregnation, the surface of the crystalline iron-aluminum or iron-aluminum-zinc metal was compared. The extent to which the compound is attached. According to this result, when the suitable case number 1, the number 2, and the number 3 of the present invention are compared with the comparative case number 4, the superiority of the amount of adhesion of the intermetallic compound can be considered.

In addition, the test material described above was cut and cut, and the presence of aluminum on the surface of the film was semi-quantitatively analyzed by SEM characteristic X-ray image. As shown in Table 3, compared with Comparative Case No. 4, the number 1 of the suitable case of the present invention was determined. The superiority of ~3. In this part, a fired film of a mixture of chrome oxide and nitride impregnated and fired on a tungsten carbide-cobalt-gold alloy molten film and a portion of the filled layer, although a part of the chromium oxide is melted Aluminum is reduced to produce a very fine metallic chromium component. However, it is presumed that the adjacent nitride is reduced in contact with the plating solution. In addition, since nitrides starting from boron nitride (BN) have a solid-slip function, they can reduce contact and adhesion to the metal plating solution in the field of grain boundaries.

[Implementation case 1]

The experimental material of the first embodiment is a surface of a roller body (made of 13Cr-based stainless steel) having a diameter of 250 mm and a surface length of 1800 mm, coated with tungsten carbide - 25 wt% of tungsten boride (W ₂ B ₅ ) - ₅ wt% of titanium boride (TiB). ₂ ) -12wt% cobalt (Co) porcelain gold spray film thickness of 0.08~0.09mm, and coating the suspension of the following components on the tungsten carbide-cobalt porcelain gold spray film, drying, and then in the atmosphere 600 ° C ± 20 ° C × 2 hours of burning. This roller body is suitable for the case of supporting the roller body (3) in the plating tank of the hot-dip galvanizing tank apparatus (1) containing 0.12% of aluminum (refer to FIG. 1).

Composition of mixed suspension for coating: The suspension was made up of a zirconium nitrate aqueous solution (concentration: 30% by weight in terms of ZrO ₂ ), and a part of stabilized zirconia (ZrO ₂ ‧8 Y ₂ O ₃ ) particle size was added. ~10μm.

Thus, the support roll body (3) was actually used in a hot-dip galvanizing bath for a hot-dip galvanized steel sheet at 460 °C. As a result, in the 20th day after the operation, a galvanized steel sheet having no problem and stable surface quality was obtained. Then, the support roller body (3) was lifted from the groove to inspect the surface of the roll body, and the precipitation and adhesion of the intermetallic compound of iron-aluminum and iron-aluminum-zinc were hardly observed. Thereafter, in order to remove the metallic zinc adhering to the surface of the roll body, the support roll body (3) was immersed in a 5% sulfuric acid (H ₂ SO ₄ ) aqueous solution for 15 minutes to remove the metal zinc.

Next, it was reinstalled and used on the molten zinc apparatus (1), and the operational life of almost the same period as the initial use was obtained. According to this embodiment, the durability life of the support roller body (3) of the conventional specification is 5 to 15 days, and the above-mentioned support roller body (3) uses the total of 2 times to extend the life by 2.5 times, and the surface quality of the steel plate is remarkably improved.

[Example 2]

The experimental material of the case 2 was a roller body having a diameter of 700 mm and a face length of 1800 mm (13Cr-based stainless steel, but the surface of the roller body was previously subjected to a thread-processed foreign matter discharge groove having a depth of 0.25 to 0.35 mm and a pitch of 2.5 mm). . The surface is coated with a tungsten carbide (WC)-30wt% chromium boride (CrB ₂ )-12wt% cobalt porcelain gold spray film having a thickness of about 0.08 to 0.09 mm, and a tungsten carbide-cobalt molten film on the surface of the roller body. The above-mentioned suspension was applied, and after drying, the roll body was fired at 600 ° C ± 20 ° C for 2 hours in an atmosphere.

The composition of the mixed suspension was obtained by using a commercially available aqueous solution of lanthanum nitrate (concentration: 30% by weight in terms of Y ₂ O ₃ ), and boron nitride (BN) having the same weight was added as an aggregate. The roller body according to the above-described treatment was actually used as the support roller body (3) of the same hot-dip galvanizing apparatus (1) as in the first embodiment, and as a result, almost the same as the embodiment, although it was once pulled up by the plating tank Pickling, but can be extended to about 45 days, and compared with the past technology, it has the effect of prolonging the durability.

[Example 3]

The experimental material of the third embodiment is a surface of a roller body (made of 13Cr-based stainless steel) having a diameter of 250 mm and a surface length of 1800 mm, coated with a tungsten carbide-12% cobalt-gold alloy molten film having a thickness of 0.08 to 0.09 mm, and a tungsten carbide here. The cobalt-gold-gold molten film was coated with a suspension of the following components and dried, and then fired at 600 ° C ± 20 ° C for 2 hours in an atmosphere. Example 3 is a case where the roll is applied to a support roll body for a molten galvanizing bath containing 0.12% of aluminum (refer to Fig. 1).

The composition of the suspended solids: a specific gravity of 1.60 chromic acid aqueous solution and a cerium nitride (Si ₃ N ₄ ) having a particle size range of 5 to 10 μm was added to the purified water to adjust the specific gravity to a specific gravity of 1.9 to 2.1, and the mixing ratio (volume ratio) was 1:1.

Thus, the above support roll body was obtained, and it was actually used in the hot-dip galvanization tank of 460 °C. As a result, a metal-plated steel sheet having no problem and stable surface quality was obtained in the 20th day after the operation. Thereafter, the support roller body was lifted from the groove to inspect the surface of the roller body, and the precipitation and adhesion of the intermetallic compound of iron-aluminum or iron-aluminum-zinc were hardly observed by visual inspection. Thereafter, in order to remove the metallic zinc adhering to the surface of the roll body, the support roll body was immersed in a 5% H ₂ SO ₄ aqueous solution for 15 minutes to remove the metallic zinc.

Next, it was reinstalled and used in a molten zinc plant, and the operational life of almost the same period as the initial use was obtained. According to the implementation case, the durable life of the support roller of the previous specification is 5 to 15 days, and the above-mentioned support roller body can be used twice to extend the life by 2.5 times, and the surface quality of the steel plate can be remarkably improved.

[Example 4]

The experimental material of the case 4 is a roller body having a diameter of 700 mm and a face length of 1800 mm (13Cr-based stainless steel, but the surface of the roller body is previously subjected to a thread-processed foreign matter discharge groove having a depth of 0.25 to 0.35 mm and a pitch of 2.5 mm). . The surface thereof is coated with a tungsten carbide (WC)-12% cobalt porcelain gold spray film having a thickness of about 0.08 to 0.09 mm, and the following suspended matter is coated on the tungsten carbide WC-12% cobalt porcelain gold film on the surface of the roller body. After drying, the roll body was fired at 600 ° C ± 20 ° C for 2 hours in an atmospheric environment.

Suspension composition: specific gravity 1.60 chromic acid aqueous solution and boron nitride (BN) particles having a particle size of 5 to 10 um were added to purified water to adjust the specific gravity to 1.30, and the mixing ratio (volume ratio) was 1:2.

The roll body according to the above treatment was actually used as the in-slot roll body in the same hot-dip galvanizing apparatus (see Fig. 1) as in the first to third embodiments. As a result, with the past technology, due to the tiny foreign matter attached to the surface of the roller body in the groove, The fine surface defects on the galvanized steel sheet gradually increase, and the roller body is changed almost every 5 days in order to increase the allowable limit of the galvanized steel surface. However, in the in-slot roll body of the above example, a galvanized steel sheet having a continuous stable surface quality can be obtained within two weeks from the start of the operation. Further, in the in-slot roll body, the surface of the roll body is taken out from the plating tank, and adhesion of iron-aluminum, iron-aluminum-zinc metal compound which causes crushing of the steel sheet is not observed, and thus it is known that The surface quality of the galvanized steel sheet has a stable effect.

As described above, according to the present invention, the surface of the steel sheet guiding roll body for the molten metal plating bath coated with the tungsten carbide-metal boride-cobalt-based porcelain gold-plated coating is coated or sprayed or impregnated. After the method is coated with a thermodynamically stable oxide and/or a nitrogen-containing aqueous solution, a thermostatically stable protective layer for the metal plating solution can be formed by a firing method, and iron-aluminum and iron present in the plating solution are The aluminum-zinc intermetallic compound particles are also not easily grown, have good durability, and can produce high-quality steel sheets with less metal-plated surface defects. On the other hand, according to the present invention, the surface of the steel sheet guiding roll body for the molten metal plating bath coated with the tungsten carbide-cobalt-based porcelain gold powder is coated or sprayed or covered with a nitride or the like by dipping or the like. After the suspension of the chromic acid aqueous solution is formed, the stable protective layer of the metal plating solution can be formed thermodynamically by the firing method, and the iron-aluminum and iron-aluminum-zinc-gold intermetallic compound particles present in the plating solution are not easily formed. With good growth, it also has good durability and can produce high-quality steel sheets with less metallized surface defects.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are Still It is within the scope of the patent of the present invention.

1‧‧‧metal plating equipment

2‧‧‧In-slot roll body

3‧‧‧Support roll body

4, 4'‧‧‧ spiral groove

Figure 1 is a schematic view of a molten metallization apparatus.

Figure 2A is a schematic view showing the grooved surface of the roller body in the groove.

Fig. 2B is a schematic view showing another groove in the surface of the roller body in the groove.

Fig. 3 is a graph showing the standard generation free energy temperature diagram of the representative of the aforementioned metal oxide used in the present invention.

Claims (5)

A method for manufacturing a roll body component for a molten metal plating solution, characterized in that a powder of tungsten carbide-metal boride-cobalt-based porcelain gold is coated on a surface of a steel substrate to form a tungsten carbide-metal boride-cobalt fusion Filming, then coating the surface of the tungsten carbide-metal boride-cobalt-based porcelain gold film with a metal oxide having a greater chemical affinity than chromium or its oxide and nitride. After the mixture and the suspension of the aqueous metal salt solution are heated and fired, in the small pores existing on the surface of the tungsten carbide-metal boride-cobalt-based porcelain gold spray film and the film layer, the coating is filled and burned and oxidized. Or a fired mixture of the oxide and the nitride, wherein the powder of the tungsten carbide-metal boride-cobalt-based porcelain gold spray film is first fired into a mixed powder of tungsten carbide and cobalt (Co). The intermetallic compound or the tungsten carbide composite compound, and then the mixed metal boride is added to the tungsten carbide-cobalt intermetallic compound or the tungsten carbide composite compound, and the binder is used as a pellet. . The method for producing a roll member for a molten metal plating solution according to claim 1, wherein the powder of the tungsten carbide-metal boride-cobalt-based porcelain gold spray film is a particle having a size of 5 to 50 μm. . The method for producing a roll member for a molten metal plating solution according to claim 1, wherein the tungsten carbide-metal boride-cobalt-based porcelain gold is titanium boride (TiB ₂ ) or zirconium boride (ZrB ₂ ). ), lanthanum boride (HfB ₂ ), vanadium boride (VB ₂ ), tantalum boride (TaB ₂ ), niobium boride (NbB ₂ ), nickel boride (NiB ₂ ), tungsten boride (W ₂ B _{5 )} Or WB), and chromium boride (CrB ₂ ) are selected from the group consisting of more than one metal boride 5 to 60 wt%, cobalt (Co) 5 to 20 wt%, and the remainder of the composition of tungsten carbide Spray construction. The method for producing a roll member for a molten metal plating solution according to claim 1, wherein the oxide is derived from neodymium (Nb), manganese (Mn), cerium (Si), zirconium (Zr), or magnesium (Mg). An oxide obtained by selecting one or more of the group consisting of calcium (Ca), titanium (Ti), aluminum (Al), and yttrium (Y). The method for producing a roll member for a molten metal plating solution according to claim 1, wherein the nitride is made of titanium nitride (TiN), zirconium nitride (ZrN), vanadium nitride (VN), and nitrided. Tantalum (TaN), aluminum nitride (AlN), boron nitride (BN), tantalum nitride (NbN), tantalum nitride (Si ₃ N ₄ ), and hafnium oxide-aluminum nitride (SiO ₂ -AlN) More than one of the selected groups is selected.