JPS595664B2 - Heat-resistant and abrasion-resistant thermal spray material - Google Patents

Description

[Detailed description of the invention] HK is used for hearth rolls for heat treatment of steel plates, stainless steel plates, etc.
Heat-resistant alloys such as 40, NA22H, and Mo-REI are used.

A build-up phenomenon occurs on the surface of these rolls during use, causing damage such as scratching the surface of heat-treated products. In blast furnaces, a matte gun is used to close the outlet of hot metal after tapping, but the nozzle at the end of the gun comes into contact with molten metal at around 1500°C for a short period of time, so it is exposed to extremely harsh conditions. .

Various heat-resistant steels were used as materials for this nozzle, but
Most heat-resistant steels have a melting point of 1450°C or less, and under severe conditions such as the nozzle at the tip of a matte gun, the melting point is approximately 1 to 1.
Can only be used twice. The material currently commonly used for this nozzle is SC, which has a low carbon content and a relatively high melting point.
material or 55 material, or even coated with Al on the surface of these materials.
Currently, 2O3 and j2 are coated with a thermally sprayed ceramic coating such as 2O3. In the case of SC material and 55 material, the number of times that it can be used is 5 to 6 times, and Al2O3 and Zr2o3
When sprayed, etc., the lifespan is about 20 to 25 times.
Apart from this, there is a radiant tube method that heats the atmosphere inside a heat treatment furnace.There are various shapes of radiant tubes, but one that is bent vertically in a W-shape is currently in use. It becomes distorted.

This distortion is one of the causes of shortening the life of the radiant tube. Therefore, the life of the radiant tube can be extended by welding a receiving metal part to the lower side of the parallel part near the bending part of the tube to support the upper part so that it can slide and prevent distortion. However, as the radiant tube is used for long periods of time at high temperatures, the part of the radiant tube that is supported so that it can slide against the receiving metal fittings will seize up and the expansion and contraction of the radiant tube will not be smooth, resulting in a problem that the lifespan will not be as extended as expected. be. The present inventor previously filed Japanese Patent Application No. 50-73352 and Japanese Patent Application No. 54-08329.
The above problems were solved by the thermal spraying materials proposed in No. 7, but these thermal spraying materials always contain W and other CO. It was economically disadvantageous because it contained expensive elements such as MO.

Therefore, the inventor conducted further research and found that W. C.O. M.O.
It has been discovered that there is a composition of thermal spraying materials that is as effective as or better than conventional ones even without the use of. The object of the present invention is that W. C.O. M.O. Japanese Patent Application No. 50-73352, Japanese Patent Application No. 54-083.
We provide a thermal spray material with performance equivalent to or even better than the thermal spray material proposed in No. 297, a hearth roll with build-up resistance, a long-life matsuto gun tip nozzle, and a nozzle that resists baking even at high temperatures. To obtain a receiving metal fitting for a radiant tube which reduces friction without causing friction.

The alloy of the present invention is not limited to these hearth rolls, mat gun tip nozzles, and radiant tube receiving metal fittings, but can be applied to all heat-resistant parts used at high temperatures of about 800° C. or higher in various atmospheres.

The composition of each component will be described in detail below, but in the main text, the definition of self-solubility is as follows. In other words, when coating the surface of a product with a thermal spray material, a melting treatment (phase treatment) is performed after thermal spraying, but at that time, it easily melts at a temperature lower than the melting point of the material, completely alloys with the material, and forms a layer at the boundary between the material and the coating layer. The property should be such that mechanical peeling does not occur.

The reason why the composition of the sprayed coating is set within the range described in the claims is as follows.

(All percentages below indicate weight%) Ni: 30-80%
If the Ni content is less than this range, the self-solubility will be extremely low, the adhesion to the material will be reduced, and the thermal sprayed coating will easily peel off during use.

Therefore, the lower limit is set to 30%. Although the objective can be achieved even if the amount exceeds this range, this element is expensive and does not meet the economical objective of the present invention, so the upper limit is set at 80%. :5-30% In order to obtain hardness not only at room temperature but also at high temperatures, it is necessary to add at least 5%.

Further, as the amount of this element added increases, it imparts heat resistance to the sprayed coating, but if the amount exceeds this range, self-fluxability is adversely affected, so it should be within this range. Si: 1-6% A minimum of 1% is required to exhibit self-solubility, and if the amount exceeds this range, it becomes difficult to form a film, and it becomes brittle, making it impossible to achieve the purpose.

Therefore, it should be within this range. : 0.1 to 2% It has the effect of increasing the strength of the sprayed coating and improving the abrasion resistance at room temperature and high temperature.

In addition, it facilitates the manufacture of the alloy, and its inclusion provides self-fluxability, making thermal spraying easier. These effects can be obtained from 0.1%, but if it exceeds 2%, carbide formation increases and becomes brittle. Therefore, it should be within this range. :O~25% It has the effect of imparting thermal shock resistance to the sprayed coating.

As the content of Fe increases, self-solubility gradually decreases, but when it does not contain W or MO, the tendency for this decrease is very slow, and even if it is contained up to 25%, there is no problem in achieving the objective of the present invention. There isn't. Furthermore, in exchange for increasing the content of Fe, the amount of expensive Ni can be reduced, which is very advantageous from the point of view of economy, which is one of the objectives of the present invention. Furthermore, even if it does not exist at all, the thermal shock resistance decreases, but there is no problem in achieving the present objective. Therefore, it should be within this range. :2.0~30%
It forms a solid solution in the base of the coating and becomes an oxide during melting treatment or during use, giving the coating oxidation resistance and heat resistance.

Moreover, when the content exceeds the solid solubility limit, it similarly becomes an oxide, which also has the effect of increasing heat resistance. This oxide is very effective in resisting build-up and also has the effect of protecting the inside of the material against molten metal. Moreover, this oxide is stable at high temperatures and is very effective in preventing seizure when it exists between metals in contact with each other.

Furthermore, the presence of Al has the effect of increasing the melting point of the coating, and as a result, it is an important element that allows the alloy of the present invention to be used at high temperatures, and is an essential element for the present invention.

It is an element that has the above-mentioned effects, and in the case of this alloy, such effects appear from 2.0%.

If the amount exceeds 30%, the same effect can be obtained, but it tends to peel off immediately after thermal spraying, after melting treatment, or during use, making operation difficult compared to the effect obtained by adding it. Therefore, it should be within this range. Next, W. M.O. ．． CO,. The reason for excluding Cu from the scope of the present invention will be described.

W,. Both MO and MO are effective elements for build-up resistance.
Moreover, it dissolves in the Ni base and has the effect of increasing the strength of the coating.

Further, a portion of it combines with C and precipitates as a carbide, which is effective in improving wear resistance from room temperature to high temperature. However, as it was used at high temperatures, W. As a result of subsequent research, it has been found that MO precipitates as a carbide, and eventually almost no longer exists in the matrix. This state causes a decrease in the strength of the Ni base, and this decrease also reduces the abrasion resistance of the coating. Also, Ni underground W. Since MO no longer exists, the build-up resistance of the ground decreases.
Also W. Due to the precipitation of MO carbides, the amount of precipitates in the coating increases, making the entire coating extremely brittle. In the end W. The effect of adding MO is remarkable at the beginning of use, but after a certain period of time, as shown in Examples 1 and 2 below, W. It was found that the lifespan was the same as that without MO.

Especially in the hearth roll. Although a build-up phenomenon occurs to some extent even in the early stages of use with a coating that does not contain MO, this effect is very slight and poses no problem in practice. Also W
．． The addition of MO deteriorates the self-solubility and makes the coating easier to peel off.

Therefore, in the thermal spray material of Japanese Patent Application No. 5,408,3297, Cu was added to improve self-fluxability, but W,...
The self-solubility is worse than a coating that does not contain MO.

Under usage conditions such as those for radiant tube receiving metal fittings, the service life is greatly influenced by the peeling resistance of the thermal sprayed coating against the material, ie, the self-fluxability, rather than the wear resistance. Therefore, as shown in Example 3, W. The alloy of the invention that does not contain MO has a longer life. For the above reasons, W. If MO is not included, there is no need to add Cu.

Next, CO dissolves in the Ni base, which increases the strength of the coating and improves its abrasion resistance. As MO is removed from the base, the limit to which the Ni-CO base can dissolve other elements increases.

9. If CO and Fe come into contact with each other in such a state, the CO and Fe will combine and cause a build-up phenomenon on the coating surface.

Seizing is also likely to occur in cases such as radiant tube receiving hardware. From the above, W. It has been found that when MO is not present, it is better not to add 5C0 either.

W. M.O. C.O. The reason why Cu is not included in the present invention is as described above. Next, a method for forming the thermal spray coating of the present invention on a material will be explained.

An alloy powder containing Al is designated as X.

Further, let Y be an alloy powder having the composition. This mixed powder of X and Y is thermally sprayed so that the composition of the coating after thermal spraying is within the scope of the claims.

Furthermore, X. The reason for mixing Y is as follows. When thermal spraying is performed using only powder X, it is difficult to form an alloy layer between the powder and the material even if phase treatment is performed, and the powder is very likely to peel off.

When only the self-fusing alloy Y is used, a sufficient alloy layer is formed between the material and the material after the phase treatment, and the peeling resistance of the sprayed coating is good.

However, due to its low melting point, the maximum operating temperature is 800-900℃.
be restricted. Therefore, by taking advantage of this good peeling resistance, the coating after phase treatment has a high melting point.
X. It is a mixture of Y. That is, X. When a mixed powder of Y is thermally sprayed onto a certain material, X. Each Y is in an independent mixed state.

When a coating with this composition is subjected to phase treatment, an alloy layer of Y is formed between it and the material, improving peeling resistance, and furthermore, an alloy layer of Y, . A layer alloyed with Y is formed. Even if an alloy powder having the composition as claimed in the claims is prepared from the beginning without using a thermal spraying material that is a mixture of X and Y, and then thermally sprayed and subjected to phase treatment, the melting point is very high as will be described later, so However, the alloy layer described above is not formed and is easily peeled off.
For the reasons mentioned above, X and Y are mixed. When Al is contained in alloy Y, the melting point of alloy Y becomes extremely high.

Therefore, even if an alloy powder having the composition as claimed in the claims is prepared from the beginning and subjected to thermal spraying and phase treatment, the high melting point of the coating makes it difficult to form an alloy layer between it and the material, resulting in very poor peeling resistance. . Therefore, the Al alloy powder is completely separated from the self-fusing alloy powder Y to form X. The reason why an alloy powder of Al and other elements is used as powder X to obtain a thermal spray coating containing Al is that when a single powder of A1 is mixed and thermal sprayed,
This is because it is difficult to obtain a desired composition because it is oxidized during thermal spraying and simultaneously scatters to the surroundings, making it difficult to obtain a thermally sprayed coating with a uniform composition.

On the other hand, when Al-alloyed powder is used, it is hardly oxidized by short-term heating during thermal spraying, and is contained in the thermal sprayed coating, making it easy to obtain a uniform target composition. Next, materials used in explaining the examples will be explained. As alloy powder X, an alloy having the composition shown in Table 1 was used.

Further, as the self-fusing alloy powder Y, one having the following composition was used. The composition of Y is not limited to this, and the amount of components outside this range can also be used, and as long as the component composition after mixing and after thermal spraying is within the claimed range, the object of the present invention can be completely achieved. It is something.

These powders The thermal spraying material is configured such that the composition of the coating after thermal spraying by mixing Y and the Z composition falls within the scope of the claims.

Examples of films alloyed with this composition are H-1 to H-1 in Table 2.
Raise it to 4. T-1 to T-23 are alloys other than the present invention listed as comparative examples. X,. When a powder mixed with Y is thermally sprayed, the formed coating contains, in addition to the components listed in the claims, Ti. Mn. Mg. Li,. Z
r. Ag, Zn. Sn,. Nb. Pb. ．． Y. It may contain Sel.

If these amounts are less than 5% in total, there will be no problem with the performance of the present invention; however, Mn, Zn. Mg. It is better not to use elements other than Pb, since they are very expensive elements and go against the objective of the present invention, which is economic efficiency. Next, examples of the present invention will be described.

Example 1 The alloy coating of the present invention was applied to the tip nozzle of a matte gun and the results of actual use are shown in Table 3.

The temperature of the hot metal at this time is approximately 1490 to 1530°C.
All matte gun materials are JISSC42. Example
2 The surface of a NA22H hearth roll (diameter 120 m77! x length 2500 mm) was thermally sprayed and tested by placing it in a galvanized line reduction furnace (temperature approximately 900 to 950°C, radiant tube heating method).

The results are shown in Table 4. The number of days in the table is the number of days until the build-up occurs. Example 3 The alloy of the present invention was thermally sprayed on the tube sliding receiving surface of the receiving metal of a radiant tube, and the results were as shown in Table 5.

As shown in Examples 1 to 3 above, the present invention can provide a thermal spray material that is comparable in performance to conventional materials, but has better performance depending on the application, at a lower cost than conventional materials. be.

Claims (1)

[Claims] 1. Alloy powder containing Al, Ni, Cr, B, Si
A heat-resistant and abrasion-resistant thermal spray material, characterized in that the composition of the thermal spray coating after thermal spraying is expressed as ▲numerical formula, chemical formula, table, etc.▼ in weight percent. 2 Alloy powder containing Al and Ni, Cr, B, Si
, C, and Fe alloy powder, and the composition of the sprayed coating after thermal spraying is expressed in weight percent, and has the following formulas, chemical formulas, tables, etc. Thermal spray material.