JPH0375351A - Seawater corrosion resisting al-mn alloy thermally sprayed steel stock - Google Patents

Abstract

PURPOSE:To obtain a seawater corrosion resisting Al-Mn thermally sprayed steel stock having high corrosion resistance and long-term stability in a seawater atmosphere and also excellent in design characteristics by forming, by thermal spraying, an Al-Mn alloy coating layer on the surface of a steel stock and further subjecting the resulting thermally sprayed layer to sealing treatment. CONSTITUTION:The surface of a steel stock for use in a highly corrosive atmosphere, such as seawater atmosphere, is subjected to descaling and surface roughening treatments by means of shot blasting treatment, etc. Subsequently, an Al-Mn alloy containing 1-40wt.% Mn is thermally sprayed on the above surface by means of plasma spraying, etc. Then, the above steel stock having the resulting thermally sprayed layer of Al-Mn alloy is immersed into a treatment solution of sulfuric acid, phosphoric acid, etc., and subjected to anodic oxidation treatment to undergo the formation of colored anodic oxidation film, and then, fine pores in the anodic oxidation film are sealed by means of vapor sealing, epoxy resin, water glass, etc. By this method, the Al-Mn alloy thermally sprayed steel stock having design characteristics and excellent in corrosion resistance and stability to seawater can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a seawater-resistant Al'-Mn alloy thermal sprayed steel material that has excellent seawater resistance and excellent design.

[Conventional technology]

Surface coating is the easiest and most commonly used method for preventing corrosion of steel materials. Surface coating methods can be roughly divided into painting methods, plating methods, and thermal spraying methods.

The painting method and the plating method are the most popular methods, but because the coating layer is thinner than the latter, the corrosion resistance is inferior for heavy-duty corrosion protection for outdoor use. Further, for example, it is not suitable for steel materials used in large structures such as thick plates and shaped steel due to restrictions on surface treatment equipment.

For this reason, thermal spraying has been used for a long time to prevent corrosion of large structures, especially when spraying Al alone, Zn alone, or Af-Zn.
Alloy spraying is often used.

[Problem to be solved by the invention]

However, when used in a seawater atmosphere (e.g.
In the case of bridge materials installed along the coast), Zn-only thermal spray coatings have a high elution rate and are inferior in corrosion protection. On the other hand, /l
'The single thermal spray coating has a lower elution rate than Zn, but it has a negative effect on the base metal, so it loses its sacrificial corrosion protection effect.
Rust is more likely to occur on scratches and cut surfaces. Also Ajl'-
It is also known to form alloy sprayed layers of Zn.

Particularly recently, maintenance-free steel products have been strongly demanded by users, as the cost of repairing steel materials for corrosion protection has been enormous and economical issues have come into focus. For this reason, conventional Zn.

Al or Al-Zn alloy thermal sprayed steel materials could not adequately cope with the problem.

Furthermore, conventional steel materials had poor surface appearance and lacked design.

Therefore, the main purpose of the present invention is to provide a seawater-resistant Al-Mn thermal sprayed steel material that has higher corrosion resistance and long-term stability than conventional thermally sprayed steel materials using Zn or Al alone, even in a seawater atmosphere, and has an excellent design. be.

[Means to solve the problem]

The above problem can be solved by having an Af-Mn alloy thermal spray coating layer with an Mn content of 1 to 40% by weight on the surface of the steel material, and further sealing the coating layer.

[For production]

In the steel material of the present invention, the Aj? - Has a Mn alloy spray coating layer. The reason why Mn is added to Al2, unlike the conventional layer, is to improve corrosion resistance and increase gloss. Furthermore, since the thermal spraying method is used, the required thickness of the coating layer can be obtained in a seawater atmosphere. Furthermore, the reason why the Mn content is set in the above range is that if it is less than 1%, the corrosion resistance is poor and the gloss is low, resulting in poor designability, while if it exceeds 40%, although both corrosion resistance and gloss are excellent, the effect is saturated. This is because it is not economical.

Further, the sealing treatment was performed on the thermal sprayed coating layer because the A1Mn thermal sprayed alloy layer itself is not dense and has poor corrosion resistance, so the sealing treatment was performed to improve the corrosion resistance.

Furthermore, by anodizing the Al'-Mn alloy sprayed coating layer, it is possible to color it appropriately and improve the design.

[Specific structure of the invention]

The present invention will be explained in more detail below.

As described above, in the present invention, an AlMn alloy is thermally sprayed onto the surface of the steel material, and if necessary, anodization treatment and sealing treatment are performed.

The Al7-Mn alloy thermal spray material in the present invention may be in powder form or linear form, but powder form is preferable from the viewpoint of ease of blending the ingredients. The thermal spray coating method is not particularly limited, but plasma spraying is preferred from the viewpoint of high speed processing.

As pre-treatments for thermal spraying, degreasing of the surface of the base material by solvent cleaning or alkaline cleaning, descaling treatment by blasting treatment, surface roughening treatment by bullet blasting treatment, etc. can be performed. The thermal spray coating layer thickness is 50 to 30
0 μm is preferable.

Regarding the sealing treatment, there are no particular restrictions, such as steam sealing, sealing with an organic material such as epoxy resin, acrylic resin, or vinyl chloride resin, or sealing with water glass.

The anodic oxidation treatment method in the present invention is carried out by electrolytic oxidation using various acid treatment solutions. As this treatment liquid, sulfuric acid, oxalic acid, phosphoric acid, dichromic acid, etc. can be used, and various colors can be produced by selecting the type of treatment liquid according to the purpose. Further, as a coloring method, in addition to anodic oxidation, dyeing, electrolytic coloring, etc. can be used.

〔Example〕

Next, the effects of the present invention will be clarified through examples.

Hot-rolled steel materials with a thickness of 10 mm were subjected to shot blasting to produce products having various Mn compositions as shown in Table 1. Thermal spraying was carried out using a plasma method using powder as the spraying material.

The conditions for post-processing are shown below.

■　Sealing treatment conditions Uses one-component air-drying epoxy resin.

■ Anodic oxidation conditions Edge treatment: Sealed with paint Treatment liquid 1: 10va 1% H, SO, Bath temperature 20°C
50A/drrfX 1 minute treatment solution 2: Oxalic acid 30 g/l + chromic acid 50 g/
l, AC 60VX 1 minute (30A/drrl') Treatment liquid 3 diphosphoric acid 4vol 1% + H2SO4 10vol 1%
, AC 60V x 1 minute (80 A/drf) Treatment liquid 4 diphosphoric acid 4 VOI% + M n S Oa 5 g
/l, AC 60VX 1 minute (50 A/d Bo) ■Electrolytic coloring conditions Electrolyte solution (9wt%NiSO4-7HzO+3wt%H3
BOj), bath temperature 20℃, 0.6 A/drrr x 1 minute For corrosion resistance, salt spray test (JISZ2371)
A comparative evaluation was made regarding the occurrence of red rust on the surface after 5000 hours. The evaluation is: ◎: No red rust at all, ○: Slightly spotty red rust, △: Partial red rust, ×: Red rust all over.
It was divided into stages.

In addition, all experiments were conducted with the Aj7-Mn sprayed film thickness being 100 μm.

The results are shown in Table 1.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to obtain a seawater-resistant Af-Mn thermal sprayed steel material that has higher corrosion resistance and long-term stability than conventional thermal sprayed steel materials even in a seawater atmosphere, and has an excellent design.

Claims (2)

[Claims] (1) Al- with a Mn content of 1 to 40% by weight on the steel surface
A seawater-resistant Al-Mn alloy thermal sprayed steel material having a Mn alloy thermal spray coating layer, which coating layer is further subjected to a sealing treatment. (2) The seawater-resistant Al-Mn alloy sprayed steel material according to claim 1, which has an anodized coating layer on the Al-Mn alloy sprayed coating layer.