JPH0645507B2 - Hot spray repair material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is for hot-spraying and repairing the lining of molten metal containers such as various steelmaking furnaces having excellent hot strength, hot adhesion, and durability. Of fireproof materials.

[Conventional technology]

In recent years, refractory materials for linings such as converters and secondary refining furnaces are expensive refractory materials that have high durability themselves, such as high-purity magnesia or electrofused magnesia, against severe steelmaking conditions. We have responded by using things. Then, against the erosion of the lining refractory, hot spraying of the refractory material is applied to the erosion area to repair the erosion, thereby achieving an overall balance, thereby extending the service life.

However, the durability of the sprayed refractory used is not sufficient, and a sprayed repair material with high durability has been developed which enables stable operation of the furnace.

For example, in the magnesia dolomite system that has been mainly used as a hot spray repair material for a converter, for example, as disclosed in JP-B-55-6598, sodium phosphate blended as a binder. Attempts have been made to improve the corrosion resistance, the adhesiveness, etc. by optimizing the type and amount of aluminum, but they have not shown sufficient durability under the recent operating conditions.

Further, in the carbon bond-based spray material, as a carbon source, it is preferable to coat the refractory aggregate with pitch, resin or the like in order to eliminate defects such as pitch, tar, etc., which are inferior in adhesiveness and adhesiveness. Japanese Patent Publication No. 61-35252 proposes to improve the durability by using pellets containing pitch, tar, etc. in a hollow capsule, but all of them are unsatisfactory in their effects. There are problems such as sufficientness and difficulty in practical use.

[Problems to be Solved by the Invention]

The problem to be solved by the present invention is to eliminate the drawbacks of the above-mentioned conventional hot-spraying repair materials, in which the hot-adhesiveness at high temperature and the excellent hot-strength under severe operating conditions. Another object is to provide a hot-blast repair material having sufficient durability.

[Means for Solving the Problems]

According to the present invention, the addition of alloy powder containing Ca and pitch is effective in improving the hot adhesion of the hot-spraying repair material mainly composed of magnesia and dolomite, and the high hot-bonding strength and high hot-strength are improved. Completed based on knowledge.

That is, the hot-spray repair material of the present invention contains 3 parts with respect to 100 parts by weight of refractory material together with a binder and other additives in an aggregate mainly composed of magnesia clinker and dolomite clinker.
It is characterized by containing 0.5 to 10 parts by weight of Ca-Si-Mg alloy powder containing 10 to 10 parts by weight of pitch and Ca content of 10% by weight or more.

Examples of the basic aggregate of the refractory used in the present invention include magnesia clinker and dolomite clinker such as natural magnesia clinker, seawater magnesia clinker, electrofused magnesia clinker, natural dolomite clinker, synthetic magnesia clinker, or carbonation of the surface thereof. Alternatively, it is possible to use one that has been treated and coated with a pitch resin or the like.

Further, it is preferable that these basic aggregates have a particle size adjusted in consideration of spraying workability, construction body structure and the like.

As binding material, phosphate, silicate, alumina cement,
Portland cement or the like can be used.

Other additives include carbon-based auxiliary binders, workability-imparting agents, various clays as binding aids, evaporative silica, slaked lime, calcium carbonate, magnesium carbonate, or various organic fibers and inorganic fibers in required amounts added as necessary. can do.

The carbon-based auxiliary binder is added to improve hot strength and corrosion resistance, and various tars, mesophase carbons, phenol resins, furan resins, furfuryl alcohol resins and the like can also be used.

[Action]

The Ca alloy powder added to the refractory material melts inside the adhered body after hot spraying, and acts as a binder at the time when it is oxidized inside the surface recesses of the object or inside the sprayed material. Improves adhesion strength and hot strength.

Further, by adding and using pitch, the hot strength is further improved and the corrosion resistance is imparted.

Further, in the case of a so-called black product-type spraying material that also uses a carbon source, in addition to the above effects, hot adhesion and hot strength are improved due to the fact that the alloy reacts with C to form carbide of a high refractory material.

Further, in the case of an alloy containing a metal element having a strong oxygen affinity, the oxidation resistance of the spray material is also improved. As the metal elements that are relatively easily available and have a strong oxygen affinity, Al, Ca,
Although Mg, Si, etc. are considered, when added to a material mainly containing dolomite, the metal or alloy containing Al is Al
After being oxidized, the reaction with CaO in the aggregate causes CaO
· _Al 2 _O 3 of _· 2SiO 2 _(m.p.1550 ℃) or binder Na ₂ O and _{Na 2 O · Al 2 O 3} · 6
Since a low melting material such as SiO ₂ (mp 1100 ° C.) is generated, the fire resistance is significantly deteriorated. Therefore, the addition of Al or an alloy containing Al to the dolomite-based material is not suitable for use because it causes deterioration in durability.

Further, addition of Si is effective for improving hot strength by forming refractory materials such as SiC, but oxidized SiO ₂ causes deterioration of corrosion resistance of basic materials, and also improves adhesion alone. Contribution to Mg melts, oxidation is fast,
Oxides are also no problem for basic materials, but lack stability due to large evaporation.

M direction and Ca have the fastest melting and oxidation reaction, and oxide improves corrosion resistance as well as Na ₂ Ca.
It also contributes to the improvement of hot strength due to the formation of a highly refractory composition such as ₄ (PO ₄ ) ₂ SiO ₂ (mp 1735 ° C.).

This highly refractory composition is considered to be produced from P ₂ O ₅ .Na ₂ O of condensed sodium phosphate used as a binder at the time of spraying and Ca and Si of the added alloy, The generation of the sample after the inter-bending strength measurement can be confirmed by X-ray analysis.

Further, the Ca-based alloy exhibits the same properties as the Al-based alloy with respect to the oxidation resistance of the carbon source in the material.

From this, the amount of Ca in the alloy must be 10% by weight or more in order to improve the hot adhesion, hot strength, and corrosion resistance of the sprayed material using dolomite. If it is less than that, sufficient hot adhesion cannot be obtained.

If the amount of the alloy added to the refractory is less than 0.5 parts by weight with respect to 100 parts by weight of the refractory, the effect of adding the alloy to the adhesiveness is not sufficient, and if it exceeds 10 parts by weight, spraying is not possible. A large amount of gas is generated due to the hydration reaction with the material, which causes deterioration of the structure of the construction body.

The amount of pitch added is preferably 3 parts by weight to 10 parts by weight with respect to 100 parts by weight of the refractory, and if less than 3 parts by weight, the performance of slag infiltration resistance is not sufficient, and if it exceeds 10 parts by weight, the construction is reversed. It causes deterioration of tissue resistance, adhesive strength, and corrosion resistance.

In particular, the addition of Ca-based alloys not only improves hot adhesion and hot strength, but also has a great effect of preventing oxidation of carbon bonds.
In that respect, addition of a carbon-based binder can maximize slag infiltration resistance, spall resistance and the like. Furthermore, the combined use with pitch addition greatly improves hot strength and corrosion resistance.

〔Example〕

Consisting of seawater magnesia clinker and synthetic dolomite clinker, 4 parts by weight of phosphate binder and 4 parts by weight of slaked lime as a hardening agent, relative to 100 parts by weight of refractory aggregate in which coarse particles, intermediate particles, and fine particles are each adjusted in particle size. Parts of the composition, Ca, Si, Mg in a weight ratio of Ca: Si: Mg
Is composed of 2: 4: 3 and Ca-S of -200 mesh or less
The i-Mg alloy powder was added in the amounts shown in Table 1 to prepare test materials. The weight ratio of Al and Mg is Al: M.
Al-Mg with g of 1: 1 and -200 mesh or less
Alloy powder was used for comparison.

Each of the test materials was sprayed on magnesia dolomite brick in a large-scale experimental furnace, cured for 15 minutes, and then the adhesive shear strength was measured. Also, the hot bending strength is measured by casting the test material in a 20 × 20 × 80 mm metal frame,
A test piece was prepared by aging for 24 hours and heated at 1450 ° C. for 3 hours.

For the evaluation of corrosion resistance, slag infiltration resistance, and oxidation resistance, a high-frequency induction furnace lining test method was used, and tests were conducted at 1700 ° C. for 5 hours.

Table 1 shows the composition of the test pieces and the test results.

As the amount of Ca-Si-Mg alloy added increases, the hot bond strength and hot bending strength improve. It is considered that the amount of refractory minerals produced increases with an increase in the amount of alloy added, which contributes greatly to the improvement of hot physical properties. If the amount added is 0.3 parts by weight, the effect is not sufficient, and if it is 15 parts by weight, it tends to deteriorate. From these results, Ca-S
It can be seen that the i-Mg alloy addition amount is suitably in the range of 0.5 to 10 parts by weight, and particularly preferably 4 parts by weight.

Further, the addition of the Al-Mg alloy shows a tendency of deterioration in each hot characteristic with an increase in the addition amount thereof, which shows that the addition to the dolomite-based material is unsuitable. The same can be judged from the results of the corrosion resistance test shown in the lower part of the table.

Table 2 shows the examination results in the pitch addition system based on magnesia-dolomite aggregate.

Nos. 10 to 15 were obtained by fixing the pitch to 7 parts by weight to the same base material as in Example 1 and observing the effect on the addition amount of the Ca-Si-Mg alloy. From the viewpoint of each hot characteristic, it is preferable that the appropriate addition amount is 0.5 to 10 parts by weight.

It was also proved that in the pitch addition system, the oxidation resistance performance was improved as the Ca-Si-Mg alloy addition amount was increased.

Nos. 16 to 19 are studies on the appropriate value of the amount of pitch added. At 2 parts by weight, the effects of hot strength and oxidation resistance are not sufficient, and at 15 parts by weight, corrosion resistance is significantly deteriorated.
The appropriate amount of pitch is judged to be 3 to 10 parts by weight.

Fig. 1 shows Ca-Si in sample Nos. 1 to 5 in Table 1.
And the addition amount of -Mg _{alloy, Na 2 Ca 4 (PO 4} ) 2 Si
It shows the relationship between the X-ray peak heights of O ₄ , and
The figure shows the relationship between the X-ray peak height and hot bending strength of the same sample. From these, it was found that the production amount of this mineral increased with the addition amount of the Ca-Si-Mg alloy, thereby improving the hot physical properties.

[Advantages of the Invention] The hot spray refractory material of the present invention provides high performance not found in conventional materials.

(1) It is possible to improve hot adhesion, hot strength, and oxidation resistance and corrosion resistance of carbon materials.

(2) As a result, it was possible to form a highly durable spray-constructed body that was not possible with conventional materials, and it was possible to significantly extend the life of the steelmaking furnace.

[Brief description of drawings]

FIGS. 1 and 2 attached herewith show the characteristics of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kosuke Kurata 1-1-1, Edamitsu, Hachimanto-ku, Kitakyushu, Kitakyushu, Fukuoka Inside the Nippon Steel Co., Ltd., Yawata Works (72) Koji Kono, Yahata, Kitakyushu, Fukuoka 1-1-1, Gikou, Higashi-ku Shin-Nippon Steel Co., Ltd. Yawata Works (72) Inventor, Taijiro Matsui 1-1-1, Gikou, Higashi-ku, Kitakyushu, Kitakyushu, Fukuoka Japan Nippon Steel Co., Ltd. Hachiman Ironworks (56) Reference JP-A-62-297273 (JP, A)

Claims (1)

[Claims] 1. An aggregate mainly composed of magnesia clinker and dolomite clinker, together with a binder and other additives, a pitch of 3 to 10 parts by weight and a Ca content of 10% by weight with respect to 100 parts by weight of a refractory material. A hot spray repair material containing 0.5 to 10 parts by weight of the above Ca-Si-Mg alloy powder.