JPH06346217A - Surface-processed member obtained by coating surface of heat and high-temperature corrosion resistant substrate - Google Patents

Abstract

PURPOSE:To provide a surface-processed member such as a roll with a coating film having improved heat resistance. CONSTITUTION:A thermally sprayed coating film, a plating film or a coating film by surface processing such as electric spark coating is immersed in a pore sealing treating agent made of an alcoholic soln. contg. halides of one or more among Mo, W, Nb, Ta, Y and lanthanoids or the film is coated with the treating agent so as to carry out pore sealing treatment and metal alkoxides of such elements are impregnated into the film. The film is then dried and fired. By this firing, the film is densified and strengthened with the elements or oxides of the elements and the objective heat and high-temp. corrosion resistant surface-processed member such as a roll with a pore sealed coating film is produced. A coating film excellent in corrosion resistance to molten metal and heat resistance in a heat treating furnace is formed and high quality of a product and a prolonged service life of the member are attained.

Description

Detailed Description of the Invention

[0001]

[Field of Industrial Application] The present invention is a surface coating having improved heat resistance by subjecting a surface-treated coating such as a thermal spray coating, a plating coating and an electric discharge coating formed on the surface of a heat resistant / corrosion resistant substrate to a sealing densification treatment. The present invention relates to a surface-treated member such as rolls having a heat treatment, and particularly to a surface-treated member whose molten metal corrosion resistance, high temperature oxidation resistance, and build-up property are improved by a sealing treatment, such as a guide roll for molten metal bath immersion plating and a heat treatment furnace. For carrier rolls.

[0002]

2. Description of the Related Art Conventionally, as a heat resistant member, the surface of the member has been subjected to thermal spraying of cermet or ceramics to impart heat resistance thereto, and further, a sealing treatment with an inorganic sealing agent has been carried out. However, the inorganic film formed is Cr ₂ O _{3 with} a chromic acid-based sealing agent, and Al ₂ O ₃ and TiO with a metal alkoxide-sol-based sealing agent that can be synthesized as a general metal alkoxide / alcohol solution. ₂ , Si
It was limited to O ₂ , ZrO _2, etc.

[0003]

However, these oxides show some reactivity in a molten zinc bath member, a roll in a heat treatment furnace near 900 ° C., etc., and adhesion of molten dross is observed on the roll surface. In the furnace roll, condensation of iron (build-up) occurred on the surface, and scratches were often seen on the plated surface and heat-treated material surface. Therefore, it has been strongly desired to develop a film that does not react with a molten metal, a soft FeO-based oxide, or the like as a heat-resistant member as described above, or a sealing treatment method. An object of the present invention is to solve the above conventional problems and provide a surface-treated member having an improved heat resistant / high temperature corrosion resistant film.

[0004]

In order to achieve the above object, the inventors of the present invention have conducted extensive studies, and as a result, have found that Nb, Ta, Y, Mo, and W having a small reactivity with molten metal and iron-based oxides.
Alternatively, the sealing and densification treatment is performed with an oxide composed of a lanthanoid element, and it has been found that the oxide of these elements is thermodynamically very stable and increases the bonding force with cermet or ceramics. The present invention has been completed.

That is, according to the present invention, Mo, W, Nb, Ta, Y is used for sealing treatment of a surface-treated coating such as a thermal spray coating, a plating film, an electric discharge coating treatment formed on the surface of a heat resistant / corrosion resistant substrate.
And a metal alkoxide of these elements is impregnated in the coating film by immersing in a sealing agent containing an alcohol solution containing one or more halides of lanthanoid elements, or by coating the treating agent, and baking after drying. However, the main point is a heat-treated, high-temperature corrosion-resistant surface-treated member having a sealed surface film, in which the film is densified and strengthened with a simple substance or an oxide of these elements. Further, the present invention uses Mo, W, Nb, Ta, Y and lanthanoid element and other heavy metal acid solutions for sealing treatment, and Mo, W, Nb, Ta, Y.
In addition, a pore-sealing treatment agent containing 10% by weight or less of an alcohol solution containing one or more halides of lanthanoid elements may be used, and the sealing treatment agent may be dipped in the treatment agent or coated and impregnated with the treatment agent, followed by firing several times. It may be a heat-treated, high-temperature corrosion-resistant surface-treated member having the surface film formed.

[0006]

The structure and operation of the present invention will be described. Nb, Ta,
The formation of oxides from halogens such as Y, Mo, W and lanthanoid elements was made possible by the reaction of Chemical formula 1.

[0007]

[Chemical 1]

That is, when a sealing agent obtained by dissolving a halide of these elements in an alcohol solvent is applied to the material to be sealed or the material to be sealed is immersed in a bath of a treatment agent, the alcohol is treated. The solute is carried into the surface film by the osmotic force of Al, and the alcohol is evaporated by heating, and then it is further heated to decompose the halide to form a metal, or to combine with oxygen to form an oxide.

By repeating such an operation several times, the pores of several μm to several tens of μm are filled and the sealing treatment is completed. The oxides of Nb, Ta, Y, Mo, W, and the lanthanoid element thus produced are extremely stable as oxides and are fine particles, and therefore exhibit an excellent sealing effect. It was also found that these oxides have a binding property with ceramics, protect the coating material, and suppress the reactivity with the molten metal and FeO. As will be apparent from the examples described later, these points have a general build-up property of Al ₂ O ₃
It is obvious from the fact that it is superior to that obtained by sealing with Cr ₂ O ₃ and Cr.

In the redox reaction as described above, in the reduction reaction when the halide is decomposed by heating and when it becomes a simple substance from the compound, these heavy metals take in the free electrons on the surface of the material to be sealed for sealing the metal. It is considered that inter-connection becomes possible.

It has also been clarified that these metals or oxides suppress the reactivity with molten metals and iron-based oxides. These are clear from the fact that the build-up property is superior to that obtained by general Al ₂ O ₃ or Cr ₂ O ₃ sealing, as will be apparent from the examples described later.

[0012]

EXAMPLES The present invention will be specifically described with reference to Examples.
This does not limit the invention. Example The various coatings shown in Table 1 were subjected to the sealing treatment of the present invention and their properties were examined. The coating was performed by thermal spraying, plating, and surface coating treatment, and compared with the case where there is no sealing treatment, the conventional chromic acid solution, colloidal silica, colloidal titania, and light metal alkoxide alcohol solution sealing treatment.

[0013]

[Table 1]

As one evaluation of heat resistance, Table 2 shows the results of a dip corrosion test in a molten zinc bath for a three-component sprayed coating. Two weeks after dipping, the comparative example and the example of the present invention were tested. There is a clear difference between and. That is, the material subjected to the pore-sealing treatment of the present invention forms a dense and strong ceramic film, so that it is less likely to be attacked by molten zinc.

[0015]

[Table 2]

Table 3 shows the characteristics of the roll in the heat treatment furnace.
It is the result of examination by a build-up property test, a Suga-type wear test, and a thermal shock test. In Table 3, the characteristics of the examples of the present invention are as follows.
It can be deduced that the dense and strong coating of the ceramics of the present invention particularly has excellent build-up characteristics and gives good results.

[0017]

[Table 3]

The build-up resistance in the above-mentioned Examples and Comparative Examples was determined by the method shown in FIG. As shown in Figure 1,
The build-up raw material 2 was sprayed on the upper surface (between B and C surfaces) on the lower side and the upper surface (A surface) on the upper side of the two thermal spray test pieces 1. The specimen was reciprocated while applying a load with a half-moon roll to evaluate the build-up status of each surface of A, B, and C. The test was performed under the conditions shown in Table 4.

[0019]

[Table 4] Specimen size: 50 × 30 × 5t (mm) Specimen material: SUS 304 Testing time: 4 hours

The evaluation is the total score obtained by the criteria shown in Table 5.

[0021]

[Table 5]

Further, the wear resistance was measured by using the equipment shown in FIG. 2 and shown by the number of reciprocations (Ds / mg) of the test piece required for 1 mg wear. The test conditions are as shown in Table 6.

[0023]

[Table 6] Specimen size: 50 × 30 × 5t (mm) Specimen material: SUS 304 As shown in Table 7, peeling resistance is obtained by repeatedly applying thermal shock by heating and cooling water, and determining the number of times until film peeling occurs. Is.

[0024]

[Table 7]

Although there are many other applications requiring heat resistance, they can be applied to hot run tables and rollers of hot-rolled steel sheet rolling lines, and rolls and molds of continuous casting equipment.

[0026]

EFFECTS OF THE INVENTION Since the present invention is constructed as described above, a coating layer having excellent corrosion resistance for molten metal and heat resistance in a heat treatment furnace is formed on the surface, and high quality of products and long life of used members are obtained. It has excellent effects such as the achievement of the above, and is extremely useful in industry.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of equipment for testing build-up resistance of a member spray-coated with a ceramic spray-coated material of the present invention.

FIG. 2 is a schematic explanatory view of equipment for testing the wear resistance of a member obtained by spray coating a ceramic spray-coated material of the present invention.

[Explanation of symbols]

 1,3 Thermal spray test piece 2 Build-up raw material 4 Thermal spray coating 5 Emery paper

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hisaro Tashiro 1-3-8 Yaesu, Chuo-ku, Tokyo Nittetsu Hard Co., Ltd. (72) Inventor Makoto Sato 1-3-8 Yaesu, Chuo-ku, Tokyo Within Tetsu Hard Co., Ltd.

Claims (3)

[Claims] 1. A kind of Mo, W, Nb, Ta, Y and a lanthanoid element for sealing treatment of a surface-treated coating such as a thermal spray coating, a plating film, an electric discharge coating treatment formed on the surface of a heat resistant / corrosion resistant substrate. The metal alkoxide of these elements is impregnated in the film by immersing in a pore-sealing treatment agent composed of an alcohol solution containing the above halide, or by coating the treatment agent, followed by drying and firing, and a simple substance of these elements. Alternatively, a heat-treated, high-temperature corrosion-resistant surface-treated member having a surface coating with a densely strengthened coating with an oxide and having a sealed surface coating. 2. A solution of Mo, W, Nb, Ta, Y, a lanthanoid element or other heavy metal acid is added to Mo, W, Nb or T.
The heat-resistant and high-temperature corrosion-resistant surface-treated member according to claim 1, which has a surface film which has been subjected to a pore-sealing treatment with a pore-sealing agent containing 10% by weight or less of an alcohol solution containing one or more halides of a and Y and a lanthanoid element. . 3. The heat-resistant, high-temperature corrosion-resistant surface-treated member according to claim 1, which has a surface coating that has been subjected to immersion or impregnation firing several times.