JPS61194167A - Coated corrosion-resistant material and its production - Google Patents

Abstract

PURPOSE:To produce a relatively inexpensive coated corrosion-resistant material having excellent corrosion resistance stably by spraying thermally Ta powder or Nb powder to the surface of a base material so as to stick said powder to the surface then subjecting the Ta or Nb film to a melting treatment by laser irradiation. CONSTITUTION:The Ta powder or Nb powder is thermally sprayed by a plasma spraying method, etc., to the surface of the relatively inexpensive base material such as carbon steel to form the Ta or Nb film having about 10-500mum thickness. The film is then subjected to the melting treatment by the laser irradiation such as CO2 laser to bind and form the dense Ta or Nb coating having no fine pores onto the base material. The inexpensive coated corrosion-resistant material having the excellent corrosion resistance possessed by Ta or Nb is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a metal material coated with Ta or Nb having good corrosion resistance and a method for manufacturing the same.

(Archived technology and its problems) Ta and Nb are metal materials with extremely excellent corrosion resistance.

For example, it does not corrode at natural immersion potential and solution oxidation-reduction potential in the normal p)l range (0-14) at room temperature. Therefore, it is an extremely promising metal as a corrosion-resistant material. However, since Ta or Nb is an expensive metal, it is not economical to use it as a structural material.Therefore, a possible method is to effectively utilize this excellent property and also be reasonable in terms of price. One way to do this is to coat an inexpensive metal base material with Ta or Nb.Plating is usually used as a method for applying a corrosion-resistant coating. However, in the case of Ta'FNb, its excellent corrosion resistance makes it difficult to generate metal ions, and therefore a Ta or Nb coating cannot be formed by plating.

In addition, thermal spraying is a method for forming Ta or Nb coatings, but the coatings formed by thermal spraying have many fine pores, making it difficult for Ta and Nb to fully demonstrate their inherent excellent corrosion resistance. Can not. For example, when carbon steel is used as a substrate and an immersion test is performed in a 10% m acid boiling liquid, Ta,
The Wb film remains, but the carbon steel of the substrate is melted.

(Object of the invention) The present invention solves the above-mentioned problems.
It is an object of the present invention to provide an inexpensive coated corrosion-resistant material having the excellent corrosion resistance of b.

(Structure of the Invention) The coated corrosion-resistant material of the present invention is a metal material covered with a Ta or Nb coating, and the Ta or Nb coating is attached to the surface of a base material by thermal spraying Ta powder or Nb powder. It is characterized by being melted by laser irradiation.

Further, the manufacturing method of the present invention is characterized in that after Ta powder or Nb powder is attached to the surface of the base material by thermal spraying, the Ta or Nb coating is melted by laser irradiation.

Here, as the base material, in order to reduce the unit price of the product, a material as inexpensive as possible, such as carbon steel, is used. However, other high-grade materials can of course also be used. In addition, to achieve the given purpose, a Ta or Nb coating with a thickness of 10 to 500p can be applied.
Apply to m.

(Embodiment) To explain the method for manufacturing the corrosion-resistant coating material of the present invention step by step, Ta or Nb powder is thermally sprayed onto the surface of carbon steel as a base material to form a Ta or Wb layer.

After Ta or Wb is deposited on the substrate to a predetermined thickness by thermal spraying, the Ta or Nb layer is melted using a laser (C02 laser). The melting point of FIATa is 2990℃,
Since the melting point of Wb is extremely high at 2470°C, it is necessary to concentrate thermal energy, and to prevent the carbon steel of the substrate from being affected by heat as much as possible, it is necessary to concentrate the energy near the surface, but a laser is used. This objective is thus fully achieved.

By melting the Ta or Nb layer, the fine pores that are a drawback of thermally sprayed coatings disappear, and the dense Ta or Nb coating is firmly bonded to the carbon steel base material.

Next, an example in which carbon steel SS41 is coated with Ta or Nb will be described.

(Example) As a metal base material, a commercially available carbon steel SS41 material with a thickness of 41 layers was used.

Ta powder or Nb powder is a normal thermal spray powder (8 to 40μ
Thermal spraying was carried out to a predetermined thickness while flowing argon gas onto the surface of carbon steel. The film thickness by one thermal spraying is usually 5 ILm, for example, in the case of thermal spraying of 1100 IL, thermal spraying is performed 20 times.The thermal spraying method was plasma spraying. A test piece (length 40 ram, width 10
mm, thickness 3 mm) was cut out. Ta of this test piece,
The Wb coating was irradiated with CO□ laser. This laser irradiation has an output of 0.5 kW, a beam diameter of 200 ILm, and a
．． The test was carried out at a speed of 5 m/min while shifting the focus. In this case, since the melting due to one pass of laser irradiation occurs within a range of approximately 0.5 layers in width, the melting portions were overlapped by 0.1 cm after the second pass (Figure 1). No melting occurred in the carbon steel of the substrate. The above laser irradiation conditions are just an example, and can be freely changed as long as the conditions can melt the Ta and Nb layers.

In this way, the corrosion resistance of the coating material irradiated with laser can be evaluated.
The test was carried out as follows.

(a) The surface of the test piece other than the one coated with Ta or Nb was coated with silicone resin, and this was immersed in a boiling solution of 10% hydrochloric acid. The resulting corrosion rate is shown in Figure 2.

As is clear from FIG. 2, carbon steel not coated with Ta or Nb was dissolved by immersion in boiling hydrochloric acid for 6 hours. When the Ta or Nb film thickness is less than 10 g, m,
Although it did not melt, it did corrode to a considerable extent. this is,
It is considered that Ta in the coating layer is caused by excessive mixing of Nb and Fe of the substrate, and the excellent corrosion resistance of Ta or Nb is degraded by Fe. When the Ta or Nb film thickness was 1Q μm or more, no corrosion occurred and the excellent corrosion resistance of Ta or Nb was exhibited. This is thought to be due to the fact that there was little Fe mixed in and the pores were eliminated by thermal spraying. However, if the Ta or Nb film thickness exceeds 800 ALm, minute cracks will occur in the coating of the laser irradiated area (some cracks will occur even at 800 μm), and its corrosion resistance will deteriorate to near the performance of carbon steel. From this, it is preferable that the Ta or Nb coating after laser irradiation has a thickness of 10 to 500 μm.

(b) The same test piece as in (a) was used as a test solution at 10%
An immersion test was carried out using a boiling solution of sulfuric acid. The resulting corrosion rate is shown in Figure 3.

As is clear from Figure 3, the test results are almost similar to those using hydrochloric acid solution, but the corrosion rate is slightly lower, so no corrosion is observed even with a coating thickness of 800 μm.Results of (a) and (b) It can be seen from the above that a surface coating material with excellent corrosion resistance can be obtained by subjecting a Ta or Nb thermal spray coating to laser treatment.

(Effect of the invention) As explained in 2 below, Ta or N is added to an inexpensive metal base material.
By forming the coating b, a material with excellent corrosion resistance can be obtained. Furthermore, the coating layer becomes dense due to thermal spraying and laser irradiation, and excellent corrosion resistance is stably exhibited regardless of the substrate material.

[Brief explanation of the drawing]

FIG. 1 shows the melted state of Ta or Nb by laser irradiation, and FIGS. 2 and 3 show the corrosion resistance of Ta and Nb coatings.

Claims (4)

[Claims] (1) A metal material covered with a Ta or Nb film, which is melted by laser irradiation after Ta powder or Nb powder is attached to the surface of the base material by thermal spraying. A coated corrosion-resistant material characterized by: (2) The coated corrosion-resistant material according to claim (1), wherein the base material is carbon steel. (3) The coated corrosion-resistant material according to claim (1), wherein the Ta or Nb coating has a thickness of 10 to 500 μm. (4) A method for producing a coated corrosion-resistant material, which comprises depositing Ta powder or Nb powder on the surface of a base material by thermal spraying, and then melting the Ta or Nb coating by laser irradiation.