JPS5842788A - Surface treated steel plate for fuel vessel - Google Patents

Abstract

PURPOSE:To obtain a surface treated steel plate for fuel vessels having corrosion resistance to gasoline contg. alcohol by applying an Sn plating layer on the upper surface of an Ni or Ni-Co alloy layer which is an underlying layer on the surface of the steel plate. CONSTITUTION:Ni or an Ni-Co alloy is plated by electroplating, etc. on the surface of a steel plate which has passed through a surface cleaning stage. An Sn plating layer is applied by a method such as electroplating on the upper layer of the underlying plating. The Sn plating layer decreases the pinholes generated in the stage of applying the underlying plating and improves corrosion resistance accompanied with the corrosion preventing effect of the sacrificing anode in the pinhole parts. If the thikness of the total plating layers of the Ni or Ni-Co alloy plating layer and the Sn plating layer are <0.25mu, many pinholes remain and if >=15mu, workability degrades; therefore said thickness are kept at 0.25- 15mu. The corrosion resistance is improved further by applying a chromate film or phosphate film thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface-treated steel sheet for containers containing fuels such as solin (so-called gasohol) and alcohol.

Conventionally, turn-plated steel sheets, which are steel sheets plated with a Pb-Sn alloy, have been used as materials for fuel containers used as gasoline tanks for automobiles.

Turn-plated steel sheets have extremely good corrosion resistance against fuels mainly composed of gasoline, and are resistant to corrosion from inevitable impurities such as moisture and S compounds contained in such fuels, and can withstand harsh forming processes such as sintering. It has good workability even for
Furthermore, it has excellent properties such as good weldability.

However, with the recent deterioration of the oil situation (rise in oil costs and reduction in production), gasoline or alcohol, which is a mixture of automobile fuel with alcohol such as methyl alcohol, ethyl alcohol, or methyl tertiary butyl ether, has been used as an alternative fuel. Although it has been proposed to use turn-plated steel sheets, the water contained in alcohol or alcohol oxides such as formaldehyde, decetaldehyde, or in some cases formic acid,
Impurities such as citric acid tend to accelerate the corrosion rate.

The present invention addresses this situation and provides a steel sheet for fuel containers that can withstand long-term use with corrosive fuels such as alcohol-containing gasoline or alcohol fuel. The gist is that the surface of the steel plate has a Ni plating layer or
Fuel of a steel plate with an i-Co alloy plating layer and a Sn plating layer, and the total thickness of the plating layer is 25 to 15μ, or a steel plate with a chromate-based or phosphoric acid-based coating layer. This is a surface-treated steel sheet for containers.

Hereinafter, the surface-treated steel sheet of the present invention will be explained in detail.

In order to impart corrosion resistance against alcohol-containing gasoline or alcohol fuel to the surface of the surface-treated original sheet manufactured through the normal steel sheet manufacturing process and surface cleaning process, Ni or Ni-Co alloy is applied by electroplating method, chemical plating method, etc.
Plate using one of the displacement plating methods. The processing conditions of the electroplating method are not particularly limited, but N is used because it allows a stable plating layer without pinholes to be obtained.
Using a Watt bath or a sulfamic acid bath in which i++ and Co were present alone or in coexistence,
It is best to process at 150A/dm2. A Sn plating layer is applied to the thus plated steel plate. Due to the superimposed effect with the Ni plating layer or the Ni-Co alloy plating layer, the Sn plating layer significantly reduces pinholes that occur during the base plating process such as the tooth plating layer, and also has a sacrificial anodic protection effect on the pinhole area. To produce a steel sheet for a fuel container, which has improved corrosion resistance and can withstand long-term use with highly corrosive fuels such as alcohol-containing gasoline. The Sn plating layer is Ni plating or Ni-C
As with the alloy plating layer, any plating method may be used (for example, electroplating is performed using a plating solution containing tin phenolsulfonate, tin sulfate, and additives (ENSA) containing Sn ions. It is preferable to perform plating at a current density of 5 to 150 A/dm2.

However, if the total thickness of the Ni plating layer or the Ni--Co alloy layer and the Sn plating layer is less than 0.25 μm, many pinholes remain and corrosion resistance cannot be obtained due to the superimposed effect of the two-layer plating described above. Furthermore, if the plated layer is thicker than 15 μm, the effect of improving corrosion resistance is saturated, and there is also the problem that the plated layer peels off or wrinkles frequently during molding or welding. Therefore, in the present invention, from the viewpoint of surface properties, the corrosion resistance of the plating layer is determined by setting the total thickness of the plating layer to 0.25 to
The thickness was set at 15μ. In particular, in a double-layer plated surface-treated steel sheet as in the present invention, the thickness of the N1 plating layer or the Ni-Co alloy plating layer, which has better corrosion resistance than Sn plating due to alcohol oxidation products, is plated with a thickness of 0.20μ or more. It is preferable to make it 50% or more of the total layer thickness.

Furthermore, for highly corrosive fuel containers, the above-mentioned surface-treated steel sheet is used by applying a chromate coating or a phosphoric acid coating. Chromate coating or phosphate coating is
It is an effective upper layer coating that seals pinholes that remain after the base plating process, improves corrosion resistance, and provides coating performance. In this case, the amount of coating is not particularly limited, but from the viewpoint of pore sealing effect and paint adhesion, chromate coating is
■/■ For 12 or more or phosphoric acid coatings, liters in terms of P/amount
q/m' or more is preferable. In addition, the chromate coating can be applied to chromic acid, chromate, dichromic acid and S04''.
"-1F-1C1-1po4--1 anion or chromic acid and chromate monosalt - Chromic acid-based aqueous solution containing silica sol, etc. that acts as an anion in the aqueous solution, for example, with a concentration of 5 g/71! to 500 g/ 11, a Cr0a bath with a temperature of room temperature to 90°C, a CrO3-H2SO4-based bath,
Cr0a-5i02 bath, Na2Cr2O7 bath, Cr
O3-H3PO4-based bath, (NH4)2Cr04-NH4
Dipping treatment, coating treatment or current density 21~ in F-based bath
This is carried out by electrolytic treatment at 100 A/dm2 and drying, or by washing with water and drying. In such electrolytic treatment (cathode electrolytic treatment), for example, in the CrO3-HaS04 system containing ion removal, the metal Cr layer deposited at the interface between the Ni plating layer and the chromate coating layer is damaged by the press machine due to the force strain phenomenon during press forming. Because the die is easily damaged, it is preferable to use a thin coating amount of 200 fjK//m 2 or less per side of the steel plate. In addition, phosphoric acid, polyphosphoric acid, phytic acid, and phosphoric acid-based aqueous solutions containing F-, So=, silica gel, alumina sol, etc., for example, with concentrations of 2.59/l to 500 scraps and temperatures of room temperature to
It is treated in a 90° C. phosphoric acid bath, phytic acid bath, phosphoric acid-NaF bath, or phosphoric acid-silica gel bath under the same steps and conditions as for the chromate coating described above.

As described above, the present invention can be applied to Ni or Ni-C0 of the base layer.
The Sn-plated metal in the upper layer, which is less potential (anode) than the alloy-plated metal, prevents corrosion of pinholes in the underlying plating layer and exhibits excellent corrosion resistance against alcohol-containing gasoline or alcohol fuel, and is a fuel with corrosion protection on one or both sides. Used as a surface-treated steel sheet for containers.

Next, a non-inventive embodiment will be described.

Example 0.8 A cold-rolled steel plate with a thickness of about 100 mm was subjected to pretreatment such as degreasing and pickling so that it had a surface quality suitable for electroplating, and then Ni plating was applied using the plating baths shown below. After that, Sn plating was performed on the upper layer. The thickness of the plating layer was varied depending on the electrolysis time.

(8) Electrolytic treatment using a tooth plating bath at a current density of 30 A/dmJ (Electrolytic treatment using a BI Sn plating bath at a current density of 20 A/dm'
Table 1 shows the performance test results for the coated steel sheets produced by the above method, untreated after coating and treated with chromate or phosphoric acid treatment. has excellent performance against alcohol-containing fuels and alcohol fuels.

(1) 1. ◎...Very good, ○...Good, △
...Slightly inferior, X...Very inferior.

2. Test by squeezing rice test material into a rectangular cylinder at a drawing ratio of 2, filling each corrosive liquid in a container, and then sealing the container.

3. After applying 5μ of future melamine alkyd paint, conduct salt water fountain test for 48 hours, and after drying, evaluate by goblin test.

Patent applicant Representative patent attorney Tomoyuki Yabuki (and 1 other person) Procedural amendment (voluntary) October 1980 220 Commissioner of the Japan Patent Office Shima 1) Haruki, 1. Display of incident Showa era patent application No. 14089
No. 1, No. 2, Title of the invention Surface-treated steel sheet for fuel containers 3, Relationship to the case of the person making the amendment Applicant's address (residence) 2-6-3 Otemachi, Chiyoda-ku, Tokyo Name (665) New Nippon Steel Corporation 4, Agent Address: 704 6-4-21 Akasaka, Minato-ku, Tokyo (1 person) 5. Subject of amendment 6. Contents of amendment (1) Specification Nos. 9 and 10 Delete Table 1 (Part 1) and (Part 2) on page 1 and replace Table 1 (Part 1) and (Part 2) as attached.
), insert (3).

(2) Insert the following sentence next to line 8 on page 11 of the same book.

[1 US (1) When using 5N60%-PB solder (Yanijin 9 solder) containing rosin alcohol flux, 300 μm of this solder was placed on the surface of the test material and held at 250°C for 30 seconds. (2) Welding strength after spot welding using a 0.8 mm steel plate under welding conditions that yield a nugget diameter of 4 mm, salt water spray test of the weld (8, 8, T48) The bondability was evaluated by taking into account the evaluation of the occurrence of red rust after 3 hours. ”

Claims (2)

[Claims] (1) Ni plating layer or Ni − on the surface of the steel plate
C. A surface-treated steel sheet for a fuel container, characterized in that an alloy plating layer is applied and then a Sn plating layer is applied, and the total thickness of the plating layer is 0.25 to 15μ. (2) Ni plating layer or Ni-Co on the surface of the steel plate
A fuel container characterized in that an alloy plating layer is applied and then an Sn plating layer is applied, the total thickness of the plating layer is 0.25 to 15μ, and - a chromate-based or phosphoric acid-based coating layer is further applied to the plating layer. Surface treated steel plate for use.