JPH0631465B2 - A ▲ l ▼ Metallic material with alloy and its manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to an A-alloy plated metal material and a method for producing the same, and particularly to a steel material provided with an A-alloy plated layer, a titanium material, a stainless steel material and a method for producing the same.

(Prior Art) It is well known that A or A alloy plated metal material has many advantages such as excellent corrosion resistance, beauty, and nontoxicity. However, since this A or A alloy plating cannot be electrodeposited from an aqueous solution, it is carried out by a molten metal dipping method, a vacuum deposition method, an electroplating method using an organic solvent bath or a molten salt electrolytic bath, and the like. As will be described later, the molten metal dipping method is mainly used at present. However, in this method, the target is almost only the plating of A, it is difficult to perform thin plating, and the treatment temperature exceeds 700 ° C., so that there is a problem that an alloy layer is formed and the base material is adversely affected.

Therefore, in recent years, attention has been paid to the latter electroplating method for the alloy A using a molten salt bath. However, although many proposals have been made for this method from the past, there are the following problems and the practical application on an industrial scale has not yet been realized.

Since smooth electrodeposition is difficult, the plated surface has many irregularities, the film lacks in denseness, and there are many pinholes that reach the substrate.

This tendency is particularly remarkable in the high current density region, and 20 A / dm
^When it is ² or more, dendrite or powdery electrodeposition is formed, which is not good for plating. Increasing the current density is essential for performing electric A alloy plating on an industrial scale from the viewpoint of improving productivity.

In particular, in the electric A alloy plating using the molten salt bath, the equipment cost increases, so downsizing of the plating tank is the most important issue, and high current density operation is indispensable. For that purpose, it is required that powder and dendrite are not generated even at a high current density of 20 A / dm ² or more, preferably 50 A / dm ² or more.

When the plating bath is deteriorated with time due to moisture absorption and the like, the electrodeposition property is further deteriorated in the case of long-term operation. However, continuous operation for a long time is indispensable together with the high current density operation as described above.

It is extremely difficult to plate a substrate such as a titanium material or a stainless steel material on which an oxide film is stably present on the surface of the material.

(Problems to be Solved by the Invention) Thus, an object of the present invention is to solve the problems of the prior art and to provide a technique capable of putting A alloy plating, particularly A alloy plating using a molten salt bath, into practical use. To do.

By the way, conventionally, A-Mn by the molten salt plating method,
Although A alloy plating such as -Pb, -Cr and -Sn has been known in the literature (Japanese Patent Publication No. 43-1825, Japanese Patent Publication No. 38-12821, Japanese Patent Laid-Open No. 5182/1983).
No. 6-62986, Japanese Patent Publication No. 53-1212, Japanese Patent Publication No. 38-6870, Japanese Patent Publication No. 46-13803, Japanese Patent Publication No. 46-29362), and according to the results of the additional experiment by the present inventors, A-Fe, With -Pb, -Cr, -Sn, etc., a good plating film was not formed when the current density was increased.

In other words, it was the current situation that these have not been sufficiently confirmed, because there were no cases in which they were put to practical use.
In addition, the corrosion resistance and other properties of the partially obtained A alloy plating are far lower than those which the A alloy originally has.

However, when the present inventors performed molten salt bath plating on these series of A alloys, in particular, A-Mn-
We found that a Cr-based alloy can be plated stably and that the resulting plating film has satisfactory corrosion resistance and adhesion, and we filed a patent application (Japanese Patent Application No. 60-78876).

Therefore, the present inventors further investigated this point, repeated experiments, Mn is effective in facilitating the initial nucleation in the electrodeposition, by adding Mn,
The present inventors have completed the present invention, knowing that each of the various alloys described above can be stably plated at a high current density.

Here, according to the experimental results of the present inventors, AX-Mn
It has been found that by using (however, X: Pb or Pb + Cr), a plating operation with a high current density of 120 A / dm ² , for example, is possible.

Furthermore, it has been clarified that the A alloy plating film stably produced as described above according to the present invention exhibits excellent corrosion resistance, and the degree thereof has been conventionally considered due to the coexistence effect of each alloy element as a ternary alloy. It was confirmed that the corrosion resistance and the adhesion were further improved as compared with each binary alloy. It should be noted that such alloy-based plating is almost impossible to obtain by the molten metal dipping method, and rather, it can be stably obtained only by molten salt plating.

Here, the gist of the present invention is that A-Mn-X (where X is Pb or Pb and Cr, Mn: 1 to 30% by weight, X: A metal material having excellent corrosion resistance, characterized by being plated with an A alloy having a composition represented by 1 to 20% by weight, A: the balance.

Furthermore, according to another feature of the invention, the invention provides
Mn-X (where X is Pb or Pb and Cr, and Mn: 1 to
30% by weight, X: 1 to 20% by weight, A: the balance) A alloy film having a composition represented by the following formula is formed on a part or the whole surface of the metal material by electroplating using a molten salt bath. And a method for producing an A alloy plated metal material.

Here, the metal material forming the base metal is not particularly limited, and is steel material, stainless steel material, titanium material or the like. Further, the shape may be any shape such as a plate material, a wire material, and a bar material. For example, it is applied to thin steel plates such as titanium rods and high-tensile steel plates for automobiles.

The alloy plating film in the present invention is easily formed by a so-called molten salt electroplating method,
For example, a plating bath containing each target metal ion may be prepared and the plating treatment may be performed therein. Usually, it may be carried out by using a molten chloride bath.

Thus, according to the present invention, A which is remarkably excellent in corrosion resistance
The alloy plating material is provided, and the A alloy plating method is proposed, which enables stable and high-speed processing at high current density.

(Function) The Mn content of the plating film of the plated metal material of the present invention is set to 1 to 30.
%, It is difficult to suppress the generation of powder and dendrite at a current density of 20 A / dm ² or more in electroplating with an A-Mn-X-based molten salt bath if less than 1%, while 30% This is because, in a range of more than 10%, the coating hardens and loses its flexibility and loses its practicality. In addition, since the hardening of the film begins to appear at about 10% Mn, practically Mn
The content is preferably 3 to 8%. Further, with such an Mn content, the A-Mn-X alloy plating is stably performed.

In the present invention, the total amount of X, that is, Pb or Pb + Cr is limited to 1 to 20%, but if X is less than 1%, A
-The high corrosion resistance and high current density operability that are the features of -Mn-X alloy are not exhibited. On the other hand, if the content exceeds 20%, the coating hardens and loses flexibility, resulting in loss of practicality. Practically, about 2 to 6% is preferable.

In addition, when co-depositing with Pb + Cr, the corrosion resistance of the coating is further improved, but the total amount is kept to 20% by weight or less. In that case, it is preferably about 2 to 6%.

Although the A content is not limited, it is preferably 60% by weight or more in order to secure the workability.

Next, the manufacturing method of the A alloy plating film according to the present invention,
Electroplating using a molten salt bath is preferable, but in this case, the molten salt bath used is for electrodeposition of A,
C 3 _-YC: 2 components (Y alkali metal) or using a multi-component mixed salt anhydrous bath, further organic amine optionally thereto, fluoride, bromide, iodide, aids and alkaline earth salts You may add as.

Eutectoid components Mn and Pb, and Cr are MnC
₂ , PbC ₂ , CrC ₂ or the like may be added to the bath in the form of a salt, or Mn or Cr metal may be added in the form of being dissolved in the bath. However, no matter which form is used, the Mn ion concentration and Pb ion concentration (or Cr ion concentration + Pb ion concentration) in the bath are 100 to 5000 ppm, and 100 to 5000 depending on the amount to be co-deposited in the film. It is necessary to adjust within the range of 10000ppm.

As described above, the form of the base metal is not particularly limited, and is usually a strip form, but as a special case, it may be a form such as a bolt or a nut.

At the start of plating, it is important to keep the treated surface clean, and especially titanium materials and stainless steel materials have a stable oxide film on the surface. It is necessary to perform sufficient pretreatment such as washing.

The surface may be previously plated with Zn in order to further improve the electrodeposition property and the corrosion resistance.

In electroplating, energization is smooth DC, ripple DC,
Either pulsed direct current may be used.

The anode may be insoluble, such as carbon or tungsten, or soluble, such as A simple substance or A alloy. When an insoluble anode is used, the bath composition changes during plating, so it is necessary to appropriately add a raw material salt or the like to keep the bath composition as constant as possible.

It is desirable that the molten salt bath be made to flow at a speed of 0.5 m / sec or more with respect to the material to be plated by stirring, pumping or the like. Also, instead of flowing the molten salt bath, the plated material is rotated,
You may move by running. Particularly in the case of a strip material, it is desirable to perform plating treatment while continuously running.

According to the present invention, the plating current density is 50 A / dm ² or more, especially 1
20A / dm ² is possible, but when the base metal is a processed product such as a bolt, it is desirable to process at low current density for a long time in order to improve throwing power. .

If relative motion is not performed between the molten salt bath and the material to be plated, it is necessary to exercise caution because kogation may occur in the plating at a current density of 10 A / dm ² or more, resulting in defective plating.

The present invention will now be further described by way of examples, which are provided solely for the purpose of illustrating the invention and are not intended to unduly limit the invention.

Example 1 A flow cell for exclusive use of molten salt (made of SUS316L) was prepared, an A plate having a purity of 99.8% was installed as an anode in the flow channel, and a cold rolled steel plate (JIS G3141) having a thickness of 0.8 mm as a material to be plated was used as a cathode As a result, the following various plating tests and the property tests of the obtained plated steel sheets were performed under the conditions shown in Table 1. The plating area was 0.7 dm ² . As a pretreatment, the cold-rolled steel sheet was degreased with an organic solvent, electrolytically degreased in 10% sodium orthosilicate, further pickled with 10% HCl, immersed in 100% ethanol, and dried with warm air. .

The first Table bath _{composition: AC 3 -NaC-KC (AC} 3:
62 mol%, NaC: 20 mol%, KC: 18 mol%) Bath temperature: 210 ° C. Additive: Mn: MnC ₂ (bath ion concentration 50-6000 pp
m) Pb: PbC ₂ (ion concentration in the bath 50 to 6000 ppm) Bath flow rate: 0.6 m / sec Energization amount: 1200 Coulomb / dm ² Current density: 20 to 120 A / dm ² Under such conditions, in the molten salt bath The Mn ion concentration and the Pb ion concentration were variously changed and the plating treatment was performed, and the relationship between the Mn and Pb concentrations in the plating film and the powder generation limit current density was investigated. The results are shown graphically in FIG.

As is clear from the data shown in the figure, powder was generated at 20 A / dm ² or more in the plating of only A containing no Mn and Pb. On the other hand, although the powder generation limit current density is improved by adding Mn and Pb, it does not reach 20 A / dm ² or more when Pb alone is added, and does not reach 50 A / dm ² or more when Mn alone is added. On the other hand, when Mn and Pb are added at the same time, the powder generation limit current density is dramatically improved, and Mn and Pb are 1 wt% each, about 50 A / dm ² , and Mn is 3 to 8 wt%. %
When Pb was 2 to 6% by weight, no powder was generated even at 100 A / dm ² . Also. The plating surface became dense with the addition of Mn and Pb, and its corrosion resistance was also significantly improved.

Similarly, CrC ₃ is added in a chromium ion concentration of 50-
The plating process was performed using a plating bath containing 6000 ppm, but the same tendency was observed.

Next, a salt spray test and a contact bending test were performed on various test materials plated with a current density of 30 A / dm ² under the same conditions and with different amounts of Mn, Pb and Cr (plating thickness 4 μm), The relationship between the plating alloy composition and SST bare corrosion resistance and adhesion was investigated. The results are summarized in Table 2.

As can be seen from the results in Table 2, M co-deposited in A
Since n, Pb and Cr together harden the film, the flexibility decreases as the eutectoid amount (content) increases.
Therefore, unless Mn is 30% by weight or less and Pb (+ Cr) is 20% by weight or less, a practically usable film cannot be obtained. Note that Mn is
If it is 10% by weight or less and Pb (+ Cr) is 8% by weight or less, pure A
Almost no decrease in flexibility was observed as compared with the case of.

Example 2 A titanium plate (thickness: 0.6 mm) was used as a base metal under the conditions shown in Table 3 under the conditions shown in Table 3 to obtain an A-Mn-Pb (-Cr) alloy (Mn: 4-8 wt%, Pb: 5-10 wt%, Cr: : 0 to 3% by weight). The same plating cell as in Example 1 was used.
As the anode, an A anode was used. Mn ions, Pb ions, and further Cr ions were added by adding powders of the respective metals to the plating bath and then dissolving them by passing through hydrogen chloride gas. The pretreatment of the base metal was carried out in the order of steam degreasing with trichloroethane, pickling with nitric hydrofluoric acid, water washing, immersion in ethanol, and cold air drying.

Although the current density was changed within the range of 10 to 120 A / dm ² , good electrodeposition was obtained in all cases. Also, the adhesion of the film is good,
No peeling was observed even in close contact bending.

In the case of this example, the initially prepared plating bath was continuously used for one month, but almost no deterioration with time was observed.

Third Table bath _{composition: AC 3 -NaC (AC 3:} 60mol%, NaC: 40mol%) Bath temperature: 220 ° C. Additives: Mn: powder (bath ion concentration 400 to 1000 ppm) Pb: powder (bath ion concentration Cr: powder (ion concentration in bath 0 to 500 ppm) Bath flow rate: 0.6 m / sec Energization amount: 1200 Coulomb / dm ² Example 3 SUS 304 stainless steel bolt under the conditions shown in Table 4,
A-Mn-Pb (+ Cr) alloy (Mn: 4-8 wt%, Pb: 5-1
0% by weight, Cr: 0 to 2% by weight) was electroplated. The bolt had a diameter of 5.2 mm and a total length of 50 mm. Cylindrical glassy carbon (inner diameter 50 mm) was used for the anode, and the stainless steel bolt to be plated was rotated at 8000 rpm in this. The pretreatment of the bolt was carried out in the order of steam degreasing with trichloroethane, pickling with hydrofluoric acid water, washing with water, immersion in ethanol, and drying with cold air.

Although the current density was changed within the range of 10 to 120 A / dm ² , all the obtained plated layers had good appearance, good adhesion and no peeling.

Fourth Table bath _{composition: AC 3 -NaC-KC (AC} 3:
70 mol%, NaC: 20 mol%, KC: 10 mol%) + Tetramethylammonium chloride (0.5 wt%) Bath temperature: 180 ° C Additive: Mn: MnC ₂ (bath ion concentration 400-1000pp
m) Pb: PbC ₂ (bath ion concentration 1000 to 2000 ppm) Cr: CrC ₃ (bath ion concentration 0 to 400 ppm) Bath flow rate: 0.6 m / sec Energization amount: 1200 Coulomb / dm ² (effect of the invention) As is clear from the description, the present invention achieves a high current density in A alloy plating in a molten salt bath without generating powder and dendrite, and thus contributes greatly to the practical application and industrialization of A alloy plating. By the usual molten metal dipping method, a plating film that is smoother and more dense and has excellent corrosion resistance than that of A plating can be obtained, and it has a great effect of suppressing the change of the plating bath over time, and its value is great. I have to say.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the Mn and Pb contents in the plating film and the powder generation limit current density.

Claims (2)

[Claims] 1. An A-alloy plated metal material having excellent corrosion resistance, characterized in that an A-alloy plated layer having a composition shown below is provided on a part or the entire surface of a base metal. A-Mn-X (where X is Pb or Pb and Cr, M
n: 1 to 30% by weight, X: 1 to 20% by weight, A: the balance). 2. A-Mn-X (where X is Pb or Pb
Cr, Mn: 1 to 30% by weight, X: 1 to 20% by weight, A
A method for producing an A alloy-plated metal material, which comprises forming an A alloy plating film having a composition represented by the remainder) on a part or the whole surface of the metal material by electroplating using a molten salt bath. .