JPS63162581A - Flame spray material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a flame sprayed material used for repairing the lining of industrial kilns such as ladles and vacuum degassing equipment.

(Prior Art) Recently, the flame spraying method has been introduced as a method for hot repairing the refractory parts of Yataneko Shiba kilns in the steel industry, and has been effective. In this method, a thermal spray material made of refractory powder is passed through a high-temperature, high-velocity flame generated by oxygen-combustible gas to melt or semi-molten the material, and then thermally spray the material to the repaired area. Compared to the conventional wet repair method, which involves adding a binder and water to refractory powder and spraying it, this flame spray repair method has a much superior repair layer structure in terms of density and adhesion. The service life can be greatly improved.

Various proposals have been made as thermal spray materials for use in this thermal spray repair method. For example, the invention of Japanese Patent Publication No. 56-23950, which combines magnesia clinker and slag, and the invention of Japanese Patent Publication No. 60-54, which uses refractory powder fired at a relatively low temperature.
There is an invention of No. 258. In general, thermal spray materials do not adhere well unless they are melted, so combinations with slag, which is a low-melting point substance, and activation of refractory aggregates by low-temperature firing are all aimed at making the thermal spray materials easier to melt. The purpose is

(Problem to be solved by the invention) However, flame spraying has a lower heat source temperature than plasma spraying (-), and when repairing industrial kilns, a large amount of material must be ejected at once due to construction efficiency. As a result, the concentration of the material in the flame becomes extremely high, and even conventional materials cannot achieve sufficient melting properties.

(Means for Solving the Problems) Improving the meltability is an essential factor for improving the adhesion and density of thermal spray materials, and as a result of repeated research to improve this point, the inventor has It was discovered that a thermal spray material with significantly superior melting properties could be obtained by combining calcined alumina and slag, leading to the completion of the present invention.

That is, the first invention of the present invention has a weight ratio of 5 to 4 slags.
This is a flame sprayed material in which the remaining part is made of lightly calcined alumina.

By the way, although the combination of lightly calcined alumina and slag has excellent melting properties, depending on the thermal spraying conditions, the combination may lead to excessive melting, resulting in a porous structure after cooling.

The second invention is a material that solves this problem in the first invention, and is a thermal spraying material consisting of slag in a weight ratio of 5 to 40%, and the balance being lightly calcined alumina and magnesia clinker.

The present invention will be explained in more detail below.

For example, the use of lightly calcined alumina as a thermal spraying material is known from Japanese Patent Publication No. 60-54258.

However, although light fired products are generally more active than fired crystals and electrofused products, their meltability is limited as they are refractory materials. In addition, slag generally adheres to the surface to be repaired, and using only a refractory material has poor wettability and poor adhesion to the surface to be repaired.

On the other hand, the combination of magnesia clinker and slag is
This is known from Japanese Patent Publication No. 56-2395. The addition of slag significantly improved the wettability with the surface to be repaired and the meltability of the thermal spray material. However, since the addition of slag also causes a decrease in the hot strength of the sprayed material, there is a natural limit to the ability to improve meltability by adding slag alone. Furthermore, materials based on magnesia clinker also have the disadvantage of poor thermal shock resistance.

On the other hand, the material according to the present invention is porous with many open pores because the alumina is light burnt, and the molten slag during thermal spraying penetrates into these pores and reacts with the alumina. Meltability is greatly improved. Moreover, since it is made of alumina as its main material, it has excellent thermal shock resistance. Alumina and slag have poor wettability due to the difference in their materials, but when alumina is lightly burnt, the slag penetrates into the pores and becomes one, and in this state it adheres to the surface to be repaired, resulting in even greater adhesion. It will be excellent.

The light calcined alumina used in the present invention is a finely powdered refractory raw material having a weight average diameter of about 50 to 80 μm, which is obtained by aluminum hydroxide obtained by the Bayer process and calcined at about 1,700 to 1,600 °C, generally about IC 100 to 1,300 °C. . A fired product obtained by further molding and firing this lightly calcined alumina, or an electrofused product melted in an electric furnace has different crystals even though they are the same alumina, and are completely distinguished from the light calcined alumina referred to in the present invention.

The slag is selected from converter slag, blast furnace slag, electric furnace slag, desulfurization slag, etc., and one or more types are all used. It may be in any form, such as a pulverized product, a spheroidized product, or a granulated product made by hardening fine powder with a binder. The particle size is, for example, 500 μm or less, preferably 300 to 10 μm. The percentage is 5% by weight
If it is less than 4Q, the meltability will be poor, and if it exceeds 4Q, the hot strength will be poor. Preferably it is 10-30%. The proportion of light calcined alumina shall be the remainder.

In the second invention, magnesia clinker is further combined.

In other words, the material made of light calcined alumina and slag becomes porous, and the magnesia clinker acts as a filler in the pores. As a result, the sprayed layer becomes denser and corrosion resistance improves.

There are two types of magnesia clinker: those made by calcining naturally occurring magnesite and those made by calcining magnesium hydroxide extracted from seawater, but it is preferable to use the latter in terms of quality such as purity.

The particle size is, for example, 500 μm or less, preferably 10 to 300 μm.
Let it be μm. The preferred proportion of magnesia is 60% by weight
It is more preferably 5 to 50%. In this case, the preferable proportion of light calcined alumina is 10 to 70%, more preferably 20 to 50%, depending on the change in the magnesia proportion.

If it exceeds 60%, the melting point of the magnesia clinker is high, resulting in poor meltability of the thermal spray material.

The thermal spraying material of the present invention is not only made of the above-mentioned raw materials, but also includes other refractory raw materials, additives, etc., as long as they do not impede the effects of the present invention.

The thermal spray material of the present invention is used, for example, in the following manner.

After using the furnace, repair the damaged parts using flame spraying. As the flame spraying device, for example, the one shown in Japanese Patent Laid-Open No. 147986/1986 can be used. That is, the thermal spray material is passed through a flame generated from a combustible gas such as propane gas or acetylene gas and oxygen to melt or semi-melt the material and weld it to the surface to be repaired. The temperature of the flame is over 2500°C at its highest point.

The furnaces to be repaired include, for example, a converter, a ladle, a vacuum degassing facility, a blast furnace hot blast furnace, a blast furnace gutter, an iron mixer car, an iron mixer, and the like.

(Example) A magnesia-chromium brick used on the inner wall of the suction pipe of D) type I vacuum degassing equipment, on which slag had adhered, was heated to a surface temperature of 1200°C, and a thermal spraying experiment was conducted.

The results are shown in Table 1 together with comparative examples.

The durability test was conducted by actually hot spraying the inner wall surface of the suction pipe of a DH vacuum degassing facility and putting it into operation.

The compositions of the thermal spray materials in Table 1 are as shown in Tables 2 and 3.

As shown in Table 1, when the thermal spraying material of the present invention is used, it is particularly dense and has excellent adhesion and adhesion properties compared to, for example, a thermal spraying material made of calcined alumina and converter slag as a comparative example.
It showed significantly superior durability.

(Effects of the invention) The thermal spraying material of the present invention combines lightly calcined alumina with slag, so that during thermal spraying, the slag penetrates into the pores of the lightly calcined alumina, improving meltability and integrating the aggregate and slag. The phenomenon of acceleration, which cannot be expected from conventional materials, results in extremely excellent adhesion, adhesion, and corrosion resistance. For example, looking at the test results in Table 3, the Examples of the present invention all exhibit three times or more durability compared to the Comparative Examples, and the effect is clear.

Claims (2)

[Claims] (1) A flame spraying material consisting of 5 to 40% slag and the balance light burnt alumina by weight. (2) A flame spray material consisting of slag in a weight ratio of 5 to 40% and the balance being lightly calcined alumina and magnesia clinker.