JPH01222089A - Amorphous alloy electroplated steel sheet and production thereof - Google Patents

Abstract

PURPOSE:To improve the corrosion resistance of a steel sheet by forming an amorphous alloy film on the steel sheet by plating with a plating bath contg. an iron family metal, an active metal, a metalloid salt, an org. acid and a neutral salt for adjusting pH at a prescribed relative flow rate. CONSTITUTION:A plating bath contg. an iron family metal (Fe, Co or Ni), an active metal (Cr, Mo or W), a salt of a metalloid (P, S, C, Si or B), an org. acid (citric acid or tartaric acid) and a neutral salt (NH4Cl) is prepd. A steel sheet is plated with the plating bath at 0.3-1.5m/sec relative flow rate to obtain an electroplated steel sheet having an amorphous alloy film of >=0.5mum thickness consisting of the iron family metal, the active metal and the metalloid.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a steel plate coated with an amorphous alloy and having excellent corrosion resistance, and a method for manufacturing the same.

[Conventional technology]

Focusing on the fact that amorphous metals have excellent corrosion resistance because they are homogeneous and do not have grain boundaries like crystalline metals and have no crystal structure inhomogeneities such as lattice defects or segregation, we have developed a method for improving the corrosion resistance of steel sheets. Various attempts have been made to apply amorphous alloy coatings to improve the performance.

When applying an amorphous alloy film to a steel plate, physical adhesion methods such as vacuum evaporation and sputtering are suitable due to the nature of the amorphous alloy to be applied, but the formation method itself is very important. Not suitable for area products or mass production;
It has drawbacks such as being expensive.

For this reason, attempts have been made to apply electroplating methods, which have conventionally been used to form large-scale corrosion-resistant films on steel sheets, for example.
Special Publication No. Sho 61-54879, Special Publication No. Sho 61-1798
It is disclosed in Publication No. 90, Patent Application Publication No. Sho 61-502263, Japanese Unexamined Patent Publication No. Sho 61-37994, etc.

[Problem to be solved by the invention]

However, amorphous alloy coated steel sheets are manufactured exclusively by vacuum evaporation methods, sputtering methods, etc., and are not suitable for large-sized products or mass production, are expensive, and are difficult to manufacture in wide widths. Disadvantages have been pointed out, such as the limited use of the method, and the unavoidable variation in quality due to the need for precision in operating conditions.

Therefore, in manufacturing an amorphous alloy coated steel sheet, it may be possible to use an electroplating method that is inexpensive, can be mass-produced, and is suitable for application to wide steel sheets.

However, when forming an amorphous alloy film by electroplating, the concentration of tungsten and phosphorus in the film is increased to form an amorphous state, and after the film is formed, the film must be under suitable control conditions. Post-treatment is required, which makes it difficult to form an amorphous plating film by electroplating.

An object of the present invention is to provide a steel sheet that can be easily coated with amorphous plating similar to conventional zinc plating, and a method for manufacturing the same.

[Means to solve the problem]

The present invention combines iron group metals such as iron, nickel, and cobalt, active metals such as chromium, molybdenum, and tungsten, and phosphorus,
It relates to an electroplated steel sheet having an amorphous alloy film consisting of a metalloid such as sulfur, carbon, silicon, boron, etc., the iron group metal, an active metal, a salt of the metalloid, citric acid,
0.3-1. Button/
It is manufactured by performing an electroplating process by giving a relative flow rate of .sec.

Furthermore, the amorphous alloy plating described above can be formed on a conventional crystalline film under similar conditions.

The thickness of the amorphous alloy plating layer of the steel sheet according to the present invention is 0.
A thickness of about 5 μm is sufficient.

FIG. 1 conceptually shows an apparatus for continuous production of amorphous alloy coated steel sheets according to the present invention.
This figure shows a strip-shaped plated steel plate traveling at a speed of . Reference numeral 5 indicates a circulating liquid storage tank of the plating bath, and the plating liquid from the circulation pump 6 is sprayed from a jet nozzle 7 onto the traveling steel plate 1 at a speed of V.

The relative flow velocity of the plating solution is vl+v2, which is 0.3 to 1.5 m/s to obtain the above amorphous alloy plating film.
The speed of ec can be easily obtained by making the running direction of these strip-shaped plated steel plates and the spraying direction of the plating solution opposite to each other. The relative flow velocity can also be obtained by slowing down the traveling speed of the steel plate and increasing the spraying speed.

Furthermore, the plating solution after spraying is circulated from the circulation path 8 to the circulation liquid storage tank 5, so that it can be reused. 9
shows the plating bath adjustment device.

The attached FIGS. 2 to 8 show the use of nickel as the iron group metal, tungsten as the active metal, phosphorus as the semimetal, citric acid as the organic acid, and ammonium chloride as the neutral salt for pH adjustment in the present invention. , shows the influence of each factor on forming an amorphous film by amorphous electroplating.

(1) Flow rate and current density Figures 2 and 3 show the influence of the relative flow rate of the plating bath when forming an amorphous film with a tungsten concentration of 25 wt%, especially the flow of the plating bath. FIG. 3 is a diagram showing the relationship between speed and limit current value.

(Citric acid 0.5 mol/β Tungsten 0.3 mol/1 Nickel 0.2 mol/β Phosphorus 0.3 mol/l Ammonium salt 0.7 mol/! pHa, 0 Temperature 70℃ electrolyte solution was made to flow. The increase in current density and the cathode potential were measured when the current density was increased.As a result, as shown in FIG. 2, it was found that by increasing the relative flow velocity V, it was possible to increase the current density.

Typical current density for static bath is 5-15 amp/dm
', but the relative flow velocity is 0.3 to 1.5 m/se
c, it is possible to increase it to 3Qamp/dm2. Furthermore, by referring to Figure 3, which shows the limiting current value due to the flow of the plating bath, the flow rate can be increased to 1.
, 5 m/sec, it is possible to use 50 to 60 amp/dm'', but it can be seen that there is almost no increase in current at a flow rate higher than that.

(2) Tungsten concentration in electrolytic bath FIG. 4 is a graph showing the influence of tungsten concentration in the bath and current density on the tungsten content in the film in a plating bath having the basic composition shown in FIG. pH8
, 0, which shows the concentration of tungsten in the bath to produce an amorphous material at a temperature of 60° C. and under the current density shown.
The tungsten content to form an amorphous film is 2
5 wt.%, which requires increasing the tungsten concentration in the bath along with the current density.

(3) Bath temperature Figure 5 shows the effect of tungsten concentration in the bath and temperature on the tungsten content in the film in a plating bath having the basic composition shown in Figure 2, when the pH is 8.0 and the current density is It was investigated under the condition of 20 amp/dm2.When the tungsten concentration is high compared to the nickel concentration, the bath temperature needs to be 50℃ or higher, and when the tungsten concentration is low, the bath temperature is 55℃. However, the upper limit of the temperature is preferably 75° C. or lower in view of operating costs.

(4) The citric acid concentration in the bath in Figure 6 is 0.15 mol of tungsten/11 mol of nickel.
．． 15 is a diagram showing the influence of organic acid (concentration of citric acid) on the content of tungsten in the plating film under the conditions of 15 mol/β, pH 6.0, and bath temperature 60°C. Referring to the figure, the tungsten content in the film (well, if the concentration of citric acid is 0.3 mol/β or less, it is not affected much by changes in current density. If it exceeds 0.3 mol/l, tungsten The amount of precipitation increases, making it possible to form an amorphous substance, but the content of tungsten etc. also increases (varies) due to the difference in current density.At 0.8 mol/1 or more, an amorphous substance is formed at any current density. Therefore, it becomes difficult to generate 0.3 to 0.8
It is preferably within the range of mol/β.

(5) pH of the plating bath Figure 7 shows that the tungsten/nickel molar ratio is 3.0,
The relationship between pH and current density given to the tungsten content in the plating film at a bath temperature of 60°C is shown. From the same figure,
It can be seen that the tungsten content in the film is greatly influenced by the pH of the plating bath.

For low current densities of 5 to 10 amp/dm, niha, p
H1-! In the case of high current density of 30 to 40 amp/dm2, the pH must also be increased to 6 to 8.

Therefore, in the operation under high current density according to the present invention, the pH must also be maintained at a high level of 6 to 8.

In addition, if pH fluctuations are expected, the current density should be increased by 2.
When it is about 0 amp/dm', an amorphous film is easily obtained.

Furthermore, phosphorus in the film is an important element for forming an amorphous film, and in order to form an amorphous film using a ternary alloy of nickel-tungsten-phosphorus, it must be contained at 10% by weight or more. There is. The phosphorus content in the plating bath is directly influenced by the phosphorus content in the coating. Figure 8 shows tungsten content of 0.15% l/jl, nickel content of 0.15 mol/1, citric acid 0.5 mol/1, and pH
6.0 and a bath temperature of 60° C. is a graph showing the relationship between the phosphorus content in the film and the phosphorus amount in the plating bath. It can be seen that the phosphorus in the film is hardly affected by the magnitude of the current density and depends on the amount of phosphorus in the bath. Therefore, the concentration of phosphorus in the bath is reduced to 0.
．． Maintaining the ratio of 3 mol/1 or more is an important condition for forming an amorphous film.

〔Example〕

The table below shows examples of the invention.

〔Effect of the invention〕

The effects of the present invention are as follows.

B. Basically, steel sheets having an amorphous coating can be obtained in large quantities relatively easily and inexpensively based on conventional electroplating methods.

Despite being thinner than conventional coatings, it is possible to obtain coatings with sufficient corrosion resistance.

C. By providing a relative flow velocity to the plating bath, high current operation becomes possible and equipment costs are reduced.

[Brief explanation of the drawing]

The attached FIG. 1 shows an example of an apparatus for carrying out the method of the present invention, and FIGS. 2 to 8 are diagrams showing the influence of each factor when forming an amorphous film by electroplating. be. 1: Plated steel plate 2: Deflector roll 3: Current roll 4: Anode 5: Circulating fluid storage tank 6: Circulation pump 7: Injection nozzle 8: Circulation path 9: Adjustment device patent applicant Tei Sangyo Co., Ltd. (and one other person) Agent Xiao Ding Yi (and 2 others) Figure 1 Figure 1￥2 Cathode potential (V vs SCE) Figure 3;'Jti! V (m/sec l Figure 4: WE5: Bath temperature ("C) 4: Figure 6: Figure 7: Electric waterfall density (A/d♂) Figure 8: Density (A/dlT2)

Claims (1)

[Claims] 1. Iron group metals such as iron, nickel, and cobalt, and chromium,
Active metals such as molybdenum and tungsten, phosphorus, sulfur,
At least 0.0% consisting of a metalloid such as carbon, silicon, or boron.
Electroplated steel sheet with a 5μm thick amorphous alloy coating. 2. An amorphous alloy film consisting of iron group metals such as iron, nickel, and cobalt, active metals such as chromium, molybdenum, and tungsten, and semimetals such as phosphorus and silicon is applied to a steel plate having a crystalline plating layer. Electroplated steel sheet formed by forming. 3. Claim 1 characterized in that the active metal content is 25% by weight or more and the semimetal content is 10% by weight or more.
An electroplated steel sheet having an amorphous alloy film according to item 1 or 2. 4. Iron group metals such as iron, nickel, and cobalt, and active metals such as chromium, molybdenum, and tungsten,
0.3 to 1.5 m/sec in a plating bath containing metalloid salts such as phosphorus, sulfur, carbon, silicon, and boron, organic acids such as citric acid and tartaric acid, and neutral salts such as ammonium chloride. ．． 1. A method for producing an electroplated steel sheet having an amorphous alloy film, characterized in that electroplating is performed while giving a relative flow velocity of . 5. A method for producing an electroplated steel sheet having an amorphous alloy film according to claim 4, characterized in that the plating bath temperature is maintained at 50° C. or higher.