JPH08134620A - Formation of amorphous sprayed coating having high corrosion resistance and wear resistance - Google Patents

Abstract

PURPOSE: To obtain a perfectly amorphous sprayed coating excellent in corrosion resistance and wear resistance. CONSTITUTION: A powder material, having a composition consisting of, by weight, 2.5-6.0% C, 5-25% Cr, 5-25% Mo, and the balance Fe, is thermally sprayed under the conditions where this powder material can be temporarily melted completely. At this time, as powder material, 5-25% Co and/or 5-25% Ni can be incorporated into the composition, and further, at least one or more kinds among 0.5-3% Si, 0.05-3% B, and 0.5-4% Al can be incorporated.

Description

Detailed Description of the Invention

The present invention relates to a method for forming an amorphous sprayed coating having excellent corrosion resistance and wear resistance.

[0002]

2. Description of the Related Art An amorphous ribbon-like thin film is obtained by rapidly solidifying an alloy in which P, Si and B are added alone or in combination with Fe by a single roll method or the like. It is known that such an amorphous metal has better corrosion resistance than a crystalline metal. However, in the prior art, in order to obtain an amorphous metal, only a rapidly solidified fine powder or a ribbon-shaped thin film was obtained.

There is also a method of forming a coating which is rapidly cooled and solidified on a metal substrate by thermal spraying, but in the conventional method, the volume ratio of amorphous is 75% or less. If a small amount of crystalline phase is present, the corrosion resistance is significantly deteriorated. Therefore, in order to obtain excellent corrosion resistance, it is necessary to obtain a 100% amorphous phase, but a coating film consisting of a completely amorphous phase has not yet been obtained by the conventional thermal spraying method.

[0004]

SUMMARY OF THE INVENTION The present invention, by selecting the composition of the thermal spray powder material and adopting the high speed thermal spraying method,
It is intended to form a sprayed coating which is completely composed of an amorphous phase and has excellent corrosion resistance and wear resistance.

[0005]

The present invention provides C2.5-
Powder material composed of 6.0 wt%, Cr 5 to 25 wt%, Mo 5 to 25 wt% and balance Fe (hereinafter referred to as the first material)
Is a method for forming an amorphous sprayed coating by spraying the first material under conditions such that the first material is completely melted once. As a powder material, Co5 to 25 wt% and Ni5 to 5% by weight are added to the first material.
A material containing at least one of 25% by weight (hereinafter referred to as a second material), the first material or the second material, and further Si 0.5 to 3% by weight, B 0.05 to 3% by weight, Al
A material containing at least one of 0.5 to 4% by weight (hereinafter referred to as a third material) can be used.

The reasons for limiting the composition of the first material will be described. C
Is an element necessary for forming an amorphous phase, and is an element for increasing the hardness of the coating. When tempered to 550 ° C or higher, C
It is an element that forms carbides with r or Mo and prevents a decrease in hardness due to high temperature tempering. If the C content is less than 2.5% by weight, an austenite phase is generated in the thermal spray coating,
On the other hand, if it exceeds 6.0% by weight, carbides are formed as it is by thermal spraying and it is difficult to become completely amorphous.
It was set to 0% by weight. Cr is an element that promotes the formation of an amorphous phase and also an element that increases the corrosion resistance of the coating. Further, as described above, when high temperature tempering is performed, a carbide is formed between the carbide and C, so that hardness reduction due to high temperature tempering is prevented. If the Cr content is less than 5% by weight, an austenite phase is likely to be generated in the sprayed coating, and the corrosion resistance is insufficient. On the other hand, even if the Cr content exceeds 25% by weight, the ease of forming an amorphous phase and the corrosion resistance do not change, so the Cr content was set to 5 to 25% by weight. Mo has substantially the same action as Cr. And the effect of adding Mo is 2
It was saturated at 5% by weight, and no improvement in properties was observed even if added in an amount greater than that. Therefore, considering the cost, the upper limit was 25% by weight.

Co and Ni contained in the second material are
It is an element that has little effect on the formation of the amorphous phase and improves the corrosion resistance. Co and Ni particularly improve the corrosion resistance to acid, but the effect is not exhibited when the amount added is less than 5% by weight, while when it exceeds 25% by weight, an austenite phase is likely to be formed, so the amount of Co and Ni is 5%. ~ 2
It was set to 5% by weight. When using Co and Ni together, Co + N
The i amount is preferably 25% by weight or less.

Si, B, and Al contained in the third material are elements that facilitate the formation of an amorphous phase. All of them are effective even if added in a small amount, but Si is less than 0.5% by weight. , B is less than 0.05% by weight, and Al is less than 0.5% by weight, the effect is not exhibited. On the other hand, if a large amount of these elements is added, the hardness of the coating becomes too high and the coating peels off during thermal spraying. Becomes Therefore, the upper limits are 3% by weight for Si and B and 4% by weight for Al.

[0009]

EXAMPLES Sample Nos. 1 and 2 shown in Table 1 below. 1-3 and NO.
The X-ray diffraction patterns of the thermal sprayed coatings Nos. 6 to 8 were determined, and it was found that all had a halo pattern that was a typical amorphous diffraction pattern, and that no crystalline phase existed.

[0010]

[Table 1]

FIG. 1 compares the corrosion resistance of the commonly used corrosion-resistant sprayed coatings of SUS316 stainless steel, Ni-base self-fluxing alloy, Hi-Teloy C and the amorphous coating of the present invention product (Sample No. 1 in Table 1 above). Result, ie 0.1 normal H ₂
5 is a comparison of anodic polarization curves at 50 ° C. in SO ₄ liquid. In the product of the present invention, formation of a passive film is observed between 0.5 and 0.9V. There is also a tendency to passivate around 1.6V. Further, it can be seen that at 0.5 V or more, the anode current density is smaller than the anode current density of the sprayed coating of the comparative material, and the corrosion resistance is superior to these coatings.

2 and 3 show the product NO. 1
~ 3 and NO. The hardness of the sprayed coatings 6 to 8 as they are sprayed and the change in hardness after being held at various tempering temperatures for 1 hour are shown.
All of the products of the present invention have a Vickers hardness of 95 while being sprayed.
It is 0 or more, and it can be seen that it is extremely hard. The product of the present invention is 5
Although there is a crystallization temperature near 00 ° C, the hardness increases when crystallized. When the tempering temperature is further increased, the hardness decreases, but the hardness as sprayed is maintained even in the tempering at 800 to 1000 ° C., and it can be said that the tempering resistance is extremely large.

FIG. 4 shows a commonly used gas sprayed coating of 13Cr steel (SUS420J) and a plasma sprayed coating of tungsten carbide 12 cobalt, and an amorphous product of the present invention (sample No. 1 in Table 1 above). The abrasion resistance test result of the coating is shown. In this test, a test piece was placed on a rotating disk grindstone, and the weight of wear was measured when a load of 300 g / cm ² was applied from above. As is clear from FIG. 4, the product of the present invention has a significantly smaller amount of wear than the comparative product and is rich in wear resistance.

20 pieces of the product of the present invention (Sample No. 2 in Table 1 above) were formed on the work surface and outer periphery of a conventional injection molding plunger.
The coating was sprayed to a thickness of 0 μm. Conventionally, this type of plunger was made of hardened steel with chrome-plated material, but its life is 2-3 months due to wear caused by silica contained in the resin and corrosion caused by chlorine gas generated from the resin. On the other hand, the product to which the above-mentioned product of the present invention was applied had a slight wear amount even after 5 months of operation and was still usable.

The product of the present invention (Sample No. 3 in Table 1) was plasma sprayed to a thickness of 500 μm on the inner surface (270 × 30) of the suction port of the submersible pump which was corroded and worn by seawater containing sand. The conventional product is made of stainless steel, and wear of 1 mm occurred in half a year, but no wear was observed in the product to which the above-mentioned product of the present invention was applied after 4 months of use.

[0016]

As described above, according to the method of the present invention, a sprayed coating consisting entirely of an amorphous phase can be obtained.
Since the thermal spray coating has excellent corrosion resistance and wear resistance, it can be applied to various fields.

[Brief description of drawings]

FIG. 1 is a graph showing anodic polarization curves of various corrosion resistant sprayed coatings.

FIG. 2 shows the product NO. It is a graph which shows the hardness at the time of tempering of 1-3.

FIG. 3 shows the product NO. It is a graph which shows the hardness at the time of tempering of 6-8.

FIG. 4 is a graph showing the wear weight of various thermal spray coatings.

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[Procedure amendment]

[Submission date] November 21, 1995

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Delete

Claims (3)

[Claims] 1. C2.5 to 6.0% by weight, Cr5 to 25
Of an amorphous sprayed film having high corrosion resistance and wear resistance, which is characterized in that a powder material consisting of 1 wt%, 5 to 25 wt% Mo, and the balance Fe is sprayed under conditions such that the powder material once completely melts. Forming method. 2. A powder material comprising the material according to claim 1 and further containing at least one of 5 to 25% by weight of Co and 5 to 25% by weight of Ni, which has a high corrosion resistance and a high wear resistance. Method for forming crystal sprayed film. 3. The powder material further comprises, in addition to the material according to claim 1 or 2, at least one of 0.5 to 3% by weight of Si, 0.05 to 3% by weight of B, and 0.5 to 4% by weight of Al. A method for forming an amorphous sprayed film having high corrosion resistance and wear resistance, characterized by being contained.