JPS60161379A - Refractory material powder for flame spray - 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 spray powder used for refractory linings of industrial furnaces and their repair.

[Prior art]

In recent years, flame spraying, which involves melting and spraying refractory powder by flying it through high-temperature, high-velocity flames, has been used for refractory lining and repair of industrial kilns, as described in, for example, Japanese Patent Application Laid-Open No. 58-110983. It started to be done.

Plasma gas spraying, which can melt or soften almost all of the refractory material, is not economically suitable for large-volume spraying such as in industrial kilns.

Therefore, for thermal spraying in ordinary industrial furnaces, LPG-oxygen,
Kerosene-oxygen and coke-oxygen flame methods have been employed. However, flames using such fuels
The theoretical flame temperature is 2600 to 2800°C, and materials with high melting points such as seawater magnesia clinker and chromite ore are difficult to melt or soften. Used in combination with alumina.

However, when using such a composite material, the adhesion of the sprayed material to the wall surface is insufficient for steelmaking converters that use basic refractories as the lining material.
Furthermore, there are drawbacks such as the composition being limited in terms of durability, especially corrosion resistance.

[Purpose of the invention]

An object of the present invention is to provide a fireproof composition that is corrosion resistant as a flame spraying material for the refractory lining of an industrial kiln even when conventional fuel is used as a flame generation source, and has good adhesion and adhesion properties. It is in.

[Structure of the invention]

Flame spraying materials + and 4 according to the present invention are made by coating a refractory material powder for repair with metals such as aluminum, magnesium, silicon, and alloys thereof that generate heat by oxidation during flame spraying and adhesion. be.

This exothermic coating material is easily oxidized even in flames using ordinary fuels such as LPG, heavy oil, and coke, and the exothermic action at that time provides additional heat to the surface of the high-melting refractory material particles. , highly active metal oxides are generated along with the heating effect of the sprayed material particles, promoting interparticle bonding. Further, the generated metal oxide and the high melting point refractory material chemically react to further promote interparticle bonding. Therefore, refractory materials with high melting points that could not be used due to insufficient flame temperature can now be used in flame spraying. The coated metal functions both as a fuel and as a refractory material.

The refractory materials used in the present invention include seawater magnesia clinker, 1 electrofused magnesia clinker, 1 sintered spinel clinker, 1 fused spinel clinker, 1 sintered picrochromite clinker, fused picrochromite clinker, and chromite ore. Refractories having a high melting point such as the above can be suitably used, but it goes without saying that it can also be applied to thermal spraying of ordinary alumina and silica refractories.

The metal material used as the coating heat generating material preferably has a thickness of 30 to 5 μm, although it depends on the properties and particle size of the refractory material.
Further, it is necessary that the amount is 0.5 to 15% by weight, and particularly preferably 1 to 10% by weight, based on the total weight of the thermal spray powder.

In coating the material particle surface with the metal, 20
Powdered material having a particle size of 0 to 30 μm is TVA
, TVP, CMC, and other known binders are used as a binder, but it is better to avoid using highly hygroscopic binders such as polyacrylic acid and its salts because they deteriorate workability due to agglomeration and the like.

〔Example〕

The present invention will be explained below with reference to Examples.

Example As shown in Table 1, 4 kg of atomized aluminum powder having a particle size of 44 μm or less was mixed with 1 op of a 7.5% aqueous solution of polyvinyl alcohol (PVA) to form a slip, and then mixed with seawater having a particle size of 150 to 10 μm. Add and mix to 95 kg of magnesia clinker (MgO 95%).

For mixing, use a heating mixer and knead the mixture at 90°C.
When dried by heating at temperatures below .degree. C., the surfaces of all seawater magnesia clinker particles are coated with atomized aluminum powder. Pass the dry powder through a 500 μm sieve.

The final particle size distribution of the dry powder is 90% between 200 and 44 μm;
The aluminum content was 4% by weight, and the binder solids content was approximately 0.75% by weight.

This thermal spray powder was applied to LPG using an LPG-oxygen flame spray gun.
PG22 Nr+? /H,021'1ONn? /H
, spraying distance I' at a powder supply rate of 40 k+r/llr
Thermal spraying was carried out on a spraying area of 0.25 nm at a diameter of 450 mm, a translation speed of 8 m/1 inch, and a preheating temperature of 1000°C.

For comparison, as shown in Table 1, alumina powder was added to uncoated seawater magnesia clinker particles with 7.
The mixed powder containing 6% by weight was thermally sprayed under the same conditions as in the previous example. As a result, as shown in Table 1, the sprayed powder construction body according to the present invention has a thermal spraying yield of about 20% compared to the comparative example.
The bulk specific gravity was improved by 1.25 times, the compressive strength was improved by 3.5 times, and the corrosion resistance was improved by 5 times.

As a result of examining the structure of the construction body according to the present invention by SEM, EPMA, and X-ray diffraction tests, it was found that no free aluminum remained.
The coated aluminum becomes corundum, which reacts with magnesia to form spinel, which well fills the space between each magnesia particle, resulting in a dense and uniform structure. On the other hand, the uniformity of the structure of the comparative example was considerably inferior.

Table 1 * Shown by the amount of corrosion after being immersed in a 1700°C mixed molten metal of converter slag and steel for 2 hours.

〔Effect of the invention〕

As is clear from the above examples, the thermal spraying refractory material of the present invention generates heat by oxidation in a flame using ordinary fuel.
It helps bonding between particles of the high melting point refractory material, and the generated active oxides form a dense compound structure with each other to form a highly durable thermal sprayed body. Further, it is possible to easily apply refractory materials with high melting points, which cannot be applied in conventional thermal spraying, and it is possible to have the effect of expanding the range of refractories that can be used.

Patent applicant Shin Nippon Seishiki Co., Ltd. (1 person) Agent Masu Kobori (1 person) Procedural amendment Commissioner of the Japan Patent Office Wakasugi Wakudono1, Indication of case 1982 Patent Application No. 138542 , Name of the invention Refractory material powder for flame solvent 3 Relationship with the case of the person making the amendment Address and name of patent applicant (665) Nippon Steel Corporation (and 1 other person) 4.
Agent's Specification 6, Details of Amendment Page 6 2 Country: Amend "approximately multiplied" to "approximately 2.0 times".

Claims (1)

[Claims] 1. A refractory material powder for flame spraying, characterized in that the refractory material powder particles are comprised of particles whose surfaces are coated with exothermic and easily oxidizable metal powder. 2. Refractory materials include seawater magnesia clinker-1 electro-fused magnesia clinker-1 sintered spinel, fused spinel, calcined alumina, sintered alumina, fused alumina, sintered picrochromite, fused picrochromite, and chromite fibers. The refractory material powder for flame spraying according to claim 1, characterized in that it is made of a material selected from the group consisting of one type or a combination thereof. 3. The refractory material powder for flame spraying according to claim 1, wherein the metal powder is any one of aluminum, magnesium, aluminum-magnesium alloy, silicon, and silicon-aluminum alloy with a diameter of 44 μm or less. 4. The flame according to claim 1, wherein the metal powder is present in an amount of 1 to 15% by weight based on the high melting point refractory material, and the particle size after coating with the metal powder is 500 to 10 μm. Refractory powder for thermal spraying.