JPH04107235A - Conductor roll for electroplating - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a conductor roll for electroplating, and particularly to a conductor roll with excellent corrosion resistance and wear resistance.

(Conventional technology) Conventionally, an acid bath method that enables plating at high current density has been used for continuous galvanizing of strips, which requires high-speed productivity, but the plating solution has high acidity and low pH. In this case, the roll surface undergoes electrolytic corrosion, causing roughness and scratches on the surface of the treated material, making it difficult to withstand long-term use. In order to prevent such deterioration in the quality of steel sheets, operations are periodically interrupted and workers h) replace the rolls themselves.

For this reason, steel rolls whose surfaces have been plated with Ni, Cr, etc. have been conventionally used. For example, JP-A-58
-141399, Ni-Cr-Mo-W alloy plating was proposed, and JP-A-60-21103
In No. 0, N1-(7~12%) Mo-(20~30%
) A current-carrying roll made of a Cr-based corrosion-resistant and wear-resistant alloy has been proposed.

(Problem to be solved by the invention) The above alloy/alloy plated fundactor roll is free from corrosion and
The wear is severe and the durability of the roll is short (h), and Oshi 1 is not sufficient for preventing surface flaws on the steel plate.

The object of the present invention is to provide a conductor roll having excellent corrosion resistance and wear resistance in acidic conditions during electroplating.

(Means for solving the problem) The present invention has Mo: 20 to 65%, Cr: 5 to 2596,
The roll is characterized by using an alloy consisting of Si: 3% or less, 0.05% or less, and the balance being Co, and at least the surface layer of the roll is made of the alloy.

The roll alloy of the present invention is a conventional N1-(7-12%) Mo-
(20-30%) Improves Cr-based alloys,
Its characteristics are that Go, which has corrosion resistance comparable to Ni and high hardness, is used as a substitute material for Ni, and the content of Mo, which has corrosion resistance, is increased.

The reasons for limiting the components of the roll alloy of the present invention will be shown below.

Co: (Remainder) Co has electrochemical stability equivalent to Ni, and as shown in Table 1, it has higher hardness than Ni, so it can improve wear resistance.

Table 1 Mo: 20 to 65% MO is an element effective in forming an electrochemically stable passive film and improving wear resistance. Furthermore, the vertical axis in Figure 1 shows the relationship between the corrosion resistance of Co-Mo-Cr alloys with varying contents of MO and Cr, which are high-hardness materials and can reduce wear by increasing their content. represents the corrosion rate (g/m2hr) in a boiling 95% sulfuric acid corrosion test (immersion time: 24 hours).

As shown in the figure, conventional Ni-(7~12%)M
o-(20~30%) Compared to Cr type, MO is 2
Corrosion resistance is improved by adding 0% or more. However, if it exceeds 65%, the amount of precipitated Mo flavor will increase, making it easier to fold and causing a decrease in toughness, so 65% is the upper limit.

C"・5-25% C" is an important element that forms a stable passive film on the metal surface and provides excellent corrosion resistance.
When r exists, a region of remarkable stability exists. But 2
If it exceeds 5%, it will become saturated and the toughness and ductility will deteriorate.

Si: 3% or less Si is effective as a deoxidizing agent, but the amount added for this purpose is sufficient to be 3% or less. In the coexistence of Cr, the solubility of Sl is low, and if it is contained in a large amount, hot cracking is likely to occur, so the St content is set to 3% or less.

C: 0.05% or less C is an element harmful to corrosion resistance, so it is desirable to have a small amount. It reacts with Cr, etc. to form carbides, suppresses coarsening of crystal grains during hot working and heat treatment, and improves yield strength and toughness and ductility. However, when the content increases, carbides precipitate in Cr at grain boundaries, reducing corrosion resistance. Since it is inferior, it is limited to 0.05% or less.

In order to manufacture a conductor roll for electroplating from the above-mentioned alloy, it is desirable to manufacture it by forging, casting, hot isostatic pressing, thermal spraying using plasma, explosion, etc.

(Example) In order to confirm the superiority of the Go-Mo-Cr-Si-C alloy in terms of wear resistance and corrosion resistance, the present inventor created an alloy with the composition shown in Table 2 by explosive thermal spraying. The following experiment was conducted using a conductor roll. FIG. 2 is a schematic diagram of the evaluation test device used in the test. S U
Made of S316, diameter 90.0mm, body length 20mm.
Various alloy coatings (200μ
m thickness) was applied. The conveying roll 2 has a urethane rubber coating on its surface and has a tension control function and a meandering prevention function. The anode electrode 3 is made of an insoluble lead alloy. Electrolytic tank 4 has 5
% sulfuric acid solution is stored in a tank, and this is circulated by an acid-resistant pump 5 and discharged from a vibro between an electrode and a steel plate 7.

As the steel plate 7, an endless belt having a thickness of 0.8 mm and a width of 50 mm was used, and the experiment was conducted by passing the plate at a speed of 45 m/win. Note that 8 is a drive roll, 9 is a tension roll, 10 is a backup roll, and 11 is a drive motor.

The test used a 5% sulfuric acid aqueous solution and a current density of 200 A/d.
The test was carried out continuously for 180 hours under conditions of m2. The surface roughness of the sample after the test was measured, and the average roughness Ra and maximum roughness R were determined.
The durability was evaluated by max.

The evaluation results are shown in Table 2, and it was found that the alloy had superior corrosion resistance and wear resistance compared to conventional Ni-based alloys.

(Effect of the invention) The conductor roll of the present invention has Mo+20 to 65%,
Cr: 5 to 25%, Si: 3% or less, 0005% or less,
By using an alloy in which the remainder is Co, corrosion resistance,
This shows a remarkable effect in that the wear resistance is significantly improved and the surface roughness is reduced to 1/2, thereby extending the life of the roll by approximately double.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between the amount of corrosion and Mo and Cr contents obtained by carrying out an electrical corrosion test on the alloy of the present invention in a boiling sulfuric acid solution. Figure 2 is a graph showing the relationship between the amount of corrosion and the Mo and Cr contents. FIG. 2 is an explanatory diagram of an evaluation test device. 1... Conductor roll 2... Conveyance roll 3... Anode t81i4
... Electrolytic tank 5 ... Acid-resistant pump 6 ... Vibrator 7 ... Steel plate 8 ... Drive roll
9...Tension roll 10...Backup roll...Driving roll and 4 others

Claims (1)

[Claims] 1 At least the roll surface layer has Mo: 20 to 65%,
A conductor roll for electroplating, characterized in that it is an alloy consisting of Cr: 5 to 2%, Si: 3% or less, C: 0.05% or less, and the balance is Co.