JPS63107872A - Magnesia lime base flame spraying material - Google Patents

Abstract

(57) [Abstract] 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 magnesia-calcareous thermal spray material used for flame spray repair of industrial kilns.

(Prior Art) It is known to repair damaged linings of industrial furnaces such as RH furnaces, DH furnaces, converters, AOD furnaces, and ladles using flame spraying. In this method, fine refractory powder is passed through a high-speed, high-temperature flame, molten or semi-molten, and then sprayed onto the damaged area. The density and strength of this material are significantly superior.

Conventionally, as a thermal spraying material used for this flame spraying, for example, Japanese Patent Publication No. 56-23950, Japanese Patent Publication No. 60-5327
Publication No. 3 also describes a material in which an appropriate amount of slag is added to the main material of magnesia clinker, as disclosed in JP-A-60-215579.
The publication proposes a material consisting of a combination of magnesia clinker and lime clinker.

(Problems to be Solved by the Invention) Addition of slag promotes melting of the thermal spray material and improves adhesion to the surface to be repaired. However, since slag is a substance with a low melting point, adding a large amount of slag lowers corrosion resistance. In addition, due to the difference in the materials between the slag and the main material, magnesia clinker, the two do not blend together, resulting in insufficient adhesion and strength after adhesion.Also, when combining lime clinker with magnesia clinker, one lime clinker is It is a fire-resistant material and does not have the effect of accelerating melting like slag. An object of the present invention is to provide a thermal spray material that solves the above-mentioned drawbacks.

(Means for Solving the Problems) As a result of repeated research, the present inventors have found that using lime clinker containing large amounts of Fe and O can improve adhesion, adhesion, and strength without reducing corrosion resistance. After learning that it is possible to obtain a thermal spray material that is excellent in the following, we completed the present invention. That is, the present invention is a magnesia-calcareous thermal spray material containing 0.1 to 10 wt% of Fe, 5 to 70 wt% of lime clinker, and the balance being magnesia clinker.

Lime clinker containing components such as AltO3,5iOz in addition to Fe, O, is known, and it is also a well-known technology to use this talin as a raw material for refractories.

However, conventionally, these components have been used as sintering agents or anti-digestion agents, and in order not to reduce the fire resistance, purity, etc. of the clinker, the amounts added are extremely small. F8J
In ff, it is usually 0.02 to 0.1 wt%.

It does not exceed 1 wt% unless it is used for special purposes.

On the other hand, lime clinker containing a large amount of 1 wt % or more of Fe and O, in combination with magnesia clinker, significantly improves the adhesion, adhesion, and corrosion resistance of the thermal spray material. Figure 1 shows magnesia clinker-50s+t%1
This is a graph of the test results of the relationship between changes in the amounts of Fe and O contained in each lime clinker and the adhesion/adhesiveness of the thermal spray material for a thermal spray material consisting of a combination of 50 wt% lime clinker.

The test method was similar to that shown in Examples below.

In addition, dolomite clinker generally has 0 Fe, O,
．． Although it is contained in a large amount of about 5 to 2 wt%, the effect of promoting melting is small, probably due to the high melting temperature of dolomite itself, and it does not have the remarkable effects of the present invention in adhesion, adhesion, and strength.

The lime clinker used in the present invention has 1 Fe, o,
It contains ~10 wt%, preferably 2-8 wt%. 1v
If it is less than t%, the effect of the present invention cannot be obtained, 10% + 1%
If it exceeds , the fire resistance of the lime clinker decreases, and the corrosion resistance of the thermal spray material deteriorates.

Lime clinker is produced in the usual manner, for example, by adding Fe, O, etc. at the slaked lime stage, and then heating at 1700 to 1800°C.
It is fired to a certain extent. Other ingredients include AI, O, S.
may contain MgO, etc., but the total amount is 2vt.
% or less is preferable.

The proportion of lime clinker in the thermal spray material is 5 to 70wt.
%, preferably 10 to 50 vt%. If it is less than 5 wt%, the effect of the present invention will not be achieved (and if it exceeds 70 wt%, the corrosion resistance will be poor.

The remainder is mainly made of magnesia clinker. In addition to magnesia clinker, dolomite clinker, spinel clinker,
Chromite, graphite, silicon carbide.

Appropriate amounts of silicon nitride, alumina, slag, aluminum minilum, etc. may be added.

The particle size of the thermal spray material is not particularly limited.

1, for example, 50 so that the jet can be smoothly ejected from the nozzle hole.
Adjust to 0 μm or less.

(Example) Examples of the present invention and comparative examples thereof are shown in Table 2.

The particle size of the thermal spray material was adjusted to 300 μm or less.

Table 1 shows the chemical composition of the raw materials used. In the lime clinker, the proportion of CaO was changed to match the proportion of Fe and 03. Magnesia clinker and dolomite clinker
used the most common one.

Table 1: Chemical composition of raw materials used (wt%) The tests shown in Table 2 were conducted on magnesia-graphite bricks heated to a surface temperature of 1200°C, which were thermally sprayed using a propane-oxygen flame as the heat source. It was measured.

(Effect of the invention) As is clear from the test results in Table 2, adding only slag, which is a low melting point substance, has excellent adhesion;
Poor corrosion resistance. The addition of lime talin with a low content of Fa, O, and lime has poor adhesion.

A dense structure cannot be obtained, and as a result, there is no sufficient effect on adhesiveness or corrosion resistance.

On the other hand, the examples of the present invention in which lime talin containing a large amount of FezO1 was added are excellent in adhesion, adhesion, and corrosion resistance. This effect is due to the low melting point substance Fe.
, 0. This is because it is added in the form of lime clinker. Therefore, according to the present invention, repair using thermal spraying material becomes even more effective, and its effects such as improving the operating rate of industrial furnaces and reducing the number of repair man-hours are extremely large.

[Brief explanation of the drawing]

Figure 1 shows Fe and O contained in lime clinker.

Claims (1)

[Claims] A magnesia-calcareous thermal spray material containing 5 to 70 wt% of lime clinker containing 1 to 10 wt% of Fe_2O_3 and the balance being magnesia clinker.