JPS63255315A - Complex nozzle and its production - Google Patents

Abstract

PURPOSE:To obtain a complex nozzle having excellent wear resistance, heat resistance, erosion resistance and thermal shock resistance at the same time and to extend the service life by heating after forming a sintered body of the specific refractory as main material and outer layer having the prescribed refractory granule on the outer side of the above body, and directly and closely contacting both layers. CONSTITUTION:In the inner side layer 1 of the complex nozzle for blowing gas or gas and powdery material into molten metal, the sintered body containing ZrB2 quality refractory as the main body, bearing the erosion caused by vigorous stirring action of the molten metal at the tip part thereof and the wear caused by inorganic powder flowing therein, that is, having characteristics of the heat resistance, erosion resistance and the wear resistance, is used. On the outer side of the inner side layer 1, C contained refractory granule of C-MgO, C-Al2O3, etc., having excellent the thermal shock resistance is packed to form the outer side layer 2 and by unburning (heating for drying) or heating for burning, the inner side layer 1 is directly and closely brought into contact with outer side layer 2. By this method, the development of gap between both layers 1, 2 and contact of the outer circumferential part of the layer 1 with the molten metal is prevented and the thermal shock resistance of the whole nozzle is improved, and the service life thereof can be extended.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a composite nozzle for injecting gas or inorganic powder together with gas into molten metal such as molten iron or steel, and a method for manufacturing the same.

[Conventional technology]

Conventionally, A1. O.

A nozzle in which a refractory material with thermal shock resistance of various oxides such as MgO and C-Al, O, c-MgO, which is a composite system of these oxides and carbon, is arranged on the outside of a metal pipe. For example, a nozzle as shown in Japanese Patent Application Laid-Open No. 60-89515 has been commonly used. Or Si□N4.
A nozzle made of a non-oxide such as 5iC, for example, JP-A-58
-163555 has been proposed.

[Problem that the invention seeks to solve]

However, nozzles made of conventional materials have insufficient corrosion resistance against molten metal and injected inorganic powder at high temperatures. Furthermore, oxides that do not contain C, 5iC1Si
A nozzle made of N4 alone does not have sufficient corrosion resistance and also does not have sufficient thermal shock resistance, so it requires preheating, and if preheating is not sufficient, it often breaks.

Furthermore, although a refractory material made of C and an oxide such as MgO1A1203 has good thermal shock resistance, it has the drawbacks of poor corrosion resistance and poor abrasion resistance against inorganic powder.

For the above reasons, there are nozzles that are used in a low temperature range or at high temperatures for a short time under certain conditions, but they are stable for long periods of time at high temperatures and are immersed in molten metal to produce inert gas or inorganic powder together with inert gas. There are almost no nozzles that inject it.

[Means for solving problems]

The present invention has been made to solve the above-mentioned problems, and its characteristic means are (1) a nozzle for blowing gas or gas and powder into molten metal, 1. A composite nozzle comprising an inner layer mainly made of a high quality refractory, and an outer layer of a carbon-containing refractory whose inner periphery is brought into direct contact with the outer periphery of the inner layer.

(2) A nozzle for injecting gas or gas and powder into molten metal, the inner layer is a cylindrical sintered body mainly made of ZrBsff refractory, and the outer layer is filled with carbon-containing refractory powder particles. to form an outer layer, which is dried in an unfired state,
Alternatively, there is a method for producing a composite nozzle, characterized in that the inner circumferential portion of the outer layer is directly brought into close contact with the outer circumferential portion of the inner layer by heating and baking to a predetermined temperature after drying.

[For production]

As shown in Fig. 1, the composite nozzle of the present invention connects the outer periphery of an inner layer 1 mainly made of ZrB2 large resistant material and the inner periphery of an outer layer 2 made of a carbon-containing refractory directly without intervening joints. It becomes close contact.

The inner side M1 is required to have high corrosion resistance and abrasion resistance to withstand erosion caused by the intense stirring action of molten metal at the tip and further to withstand wear caused by inorganic powder flowing inside. By using a dense sintered body of ZrB, this characteristic can almost be satisfied.

Next, the outer part 2 needs to have thermal shock resistance that will not break when inserted into a molten metal or a high-temperature furnace, and this property is satisfied by using a carbon-containing refractory.

Here, as a ZrB quality refractory, first of all, ZrB is the material.
As long as it has rBa (zirconium diboride) as its main component (ZrB consists of all or most of the large component, it can exhibit the desired effect as ZrB as its main component). A variety of things can be used including those included.

Some desirable compositions are as follows.

(Weight%) 1. ZrB28G~98% SiC2~20% 2. ZrB1 80~90% Al,
0310~20% 3, ZrB, 70~95%BN
5-20% SiC5-10% 4, ZrB, 80-95%C5
~20% 1.2.4 SiC, Al, 03. It is desirable that the amount of C be 20% or less; if it is more than this, the corrosion resistance will deteriorate, which is not preferable.

Although those containing BN of No. 3 have excellent thermal shock resistance, the content is preferably 20% or less in terms of corrosion resistance and strength.

SiC added at the same time is effective in improving oxidation resistance, but it lowers corrosion resistance, so the composition range described above is desirable.

Compositions 1.2.4 have particularly excellent corrosion resistance and wear resistance and are suitable as nozzles for injecting gas and inorganic powder into molten metal, while compositions 3 are mainly suitable for use in high-temperature heating furnaces.

In addition, in terms of physical properties, the following materials are desirable for the inner layer of the nozzle.

Relative density 80% or more, preferably 90% or more Bulk specific gravity 4
Bending strength (kg/cd) Normal temperature: 1000 or more, preferably 3000 or more, 1400
°C 500 or higher, preferably 500 or higher Vickers hardness (kg/alab") Room temperature 500 or higher, preferably 800 or higher 1400°C 300 or higher, preferably 500 or higher Melting point 2000 °C or higher High density is desirable in order to withstand erosion and abrasion when inorganic powder passes inside.High bending strength and hardness are also desirable for the same reasons.

In particular, the bending strength is desirably 1000 kg/a# or more in order to prevent cracking during integral molding of ZrB2 and C-MgO.

Next, as the carbon-containing refractory, those that have been used in conventional nozzles of this type can be used as they are.

That is, Mg0-C, A1. Any material such as O, -C, ZrO, or -C may be used. Here, C is generally graphite, and its blending ratio is usually about 10 to 30% by weight for the C-containing refractory layer.

The nozzle of the present invention has such a two-layer structure, an inner and outer layer, and its manufacturing method involves using a pre-sintered cylindrical ZrB refractory as a core, for example, a middle part of a rubber mold, and a rubber mold. A carbon-containing refractory raw material is loaded between the inner walls of the mold, and filled while being vibrated in the rubber mold. This is further applied a pressure of 1000 kg/a or more in hydraulic pressure (rubber press) to form a dense outer layer. By heating and drying this at, for example, 200 to 300°C for 5 minutes, the outer periphery of the inner layer and the inner periphery of the outer layer are brought into direct contact with each other without intervening joints, resulting in peeling and gaps during use. Thus, a desirable product can be obtained that can prevent molten metal intrusion and corrosion loss.

In the composite nozzle of the present invention, the thicknesses of the inner layer and the outer layer m are preferably as follows.

Inner layer 10-20ml11 Outer ffJ 20-100mm It is sufficient that the inner layer ZrB has a wall thickness of 10 m/m or more, and if it is 20+*/m or more, it is preferable because the temperature difference between the inner and outer surfaces makes it more likely to break. do not have.

The outer carbon-containing layer preferably has a thickness of 20m+o or more due to powder formability and corrosion resistance against molten metal.
om/m is sufficient.

In addition, by sloping the outer periphery of the ZrB refractories, which are the inner layer, as shown in Figure 1 (a), even if a crack occurs in the inner layer, the outer layer can be easily removed. can prevent peeling.

Since the binder contained in the carbon-containing layer of the outer layer is usually a thermosetting resin, it is hardened by heating and drying at 200 to 300°C for 5 hours or more as described above, and then reduced and fired at about 1000°C. When the resin is carbonized, the adhesion between the inner layer and the outer periphery becomes stronger, and peeling and gaps during use can be reliably suppressed, and molten metal intrusion and erosion can be prevented.

〔Example〕

Example 1 A Zr132 pipe (Note 1) is used as a core, Mg0-C raw material (Note 2) is loaded on the outside, and 1500 kg/af?
By rubber press molding under pressure and drying at 250°C for 5 hours, the product has a length of 200 mm, a wall thickness of 30 mm, and an inner diameter of 1.
A composite nozzle of 1+I1m was obtained. (ZrB2 thickness LovA
/m, Mg0-C thickness 20m/m) (Note 1) Composition ZrB2: 95%, SiC5% Physical properties Density:
5.60 Bending strength (kg/a1.room temperature): 4000 bit force-
Hardness (kg/mm", room temperature): 1300 (Note 2) Composition: 80% MgO, 20% graphite, 4% binder. (MgO5~1m/m 40%, MgO1nua
-25%, MgO0, lmm-15%, flaky graphite 0.
(5 mm - 20%, phenol resin outer layer: 4%) This composite nozzle was then immersed and stirred in molten steel without preheating while flowing argon under the following conditions.The results were as follows.

Conditions: Molten steel temperature 1550-1600℃ Immersion time 18
0 min/Charge Argon gas flow rate 50Q/min Result: Argon gas could be stably flowed during immersion.

After immersion, no peeling due to cracks was observed in both materials of the nozzle.* There was almost no erosion or adhesion of bare metal to the ZrB2 inner layer, and there was no peeling damage to the inner or outer layers after 13 days.
It was possible to reuse the charge.

Example 2 The same nozzle as in Example 1 was immersed in molten steel without preheating while flowing argon gas together with CaC01 powder under the following conditions. The results were as follows.

Conditions: Molten iron temperature: 1510-1560℃ Immersion time:
60mln/charge Ar gas flow rate: 100 Q/winCaCO, flow rate: long/win Particle size 0. IIm Under-result: There was no clogging of the nozzle during immersion, and after immersion, there was only slight wear and adhesion of steel and slag to the nozzle tip, giving good results. After that, it was possible to reuse it for 20 charges.

Example 3 Compared to the nozzle of Example 1, the outer layer was changed to Mg0-C to A1.03-C (the blend was that the MgO in Example 2 was replaced with A1
A heat-formed composite nozzle filled with □03) was inserted into the molten iron while flowing a mixture of nitrogen gas and soda ash.

Conditions: Molten iron temperature: 1510-1560℃, no preheating Use time: 3Gmin/Charge N2 gas flow rate: 50 Q/akinNa, CO,
Flow rate: 300g/lll1n0.1 +m underresult: Good results with no nozzle clogging during insertion. After completion At, 0. Although the -C layer portion was oxidized over a thickness of several mm, there was no problem at all in the ZrB2 portion. After that, 19 charges could be reused.

Comparative Example 1 ZrB was immersed in molten steel while argon gas was flowing inside a single nozzle (ZrB, 95%).

Conditions: Molten steel temperature: 1550-1600°C, no preheating Immersion time: 5 minutes/charge Number of charges: 1 charge Argon gas flow rate: 1OQ/min Results: After 5 minutes of immersion, the ZrB nozzle cracked and was damaged, so the experiment was interrupted. .

Comparative example, 2 ZrB, C-Mg with holes formed in the pipe in advance
A nozzle, which was created by penetrating into an O-based cylinder and fixed using an inorganic adhesive, was immersed in molten steel while flowing Ar.

Conditions: Molten steel temperature: 1550-1600℃ Immersion time:
30m1n/channel argon gas flow rate = 10α/min Result: After use, the boundary between ZrB and Mg0-C was selectively eroded by about 20s/m and the steel had penetrated, making reuse impossible. Ta.

Comparative Example 3 Mg0-C-based large resistant material (MgO
5-1mm 40%, 1m@25% or less, 0.1aua
A composite nozzle is heated and formed by filling with 15% or less of flaky graphite, 0.5ml or less of flaky graphite, 20% of phenolic resin and 4% with a phenol resin outer layer, and pours Ar gas and calcium carbonate powder inside the nozzle into the molten steel. Immersed 16 Conditions: Molten steel temperature: 1550-1600℃, no preheating Immersion time: 60ml1n Ar gas flow rate: 100jl/winCaCO, flow rate: 100g/win 0.1m underresult: After immersion, the nozzle tip is about 10mm The adjacent C-MgO portion was also worn away by approximately 20 m/m, and the hole diameter at the nozzle tip was observed to be enlarged.

It was also observed that a considerable amount of metal was attached to the tip of the stainless steel.

After that, the nozzle became clogged during the second charge. It became unusable.

[Effects of the present invention] As described above, the nozzle of the present invention is a composite nozzle that is made of a specific inner and outer two-layer refractory material and has the inner and outer two layers in direct contact with each other, and exhibits the following effects. be done.

First, the corrosion resistance required for molten metals and inorganic powders is solved by using ZrB2 material, which has excellent heat resistance and corrosion resistance, for the inner layer. ZrB has a melting point of 3060℃
Fe, Cu, which has high heat resistance and low melting point.
It is known that it does not react with Pb, Zn, Al, Sn, and other metals. It also has excellent wear resistance against fluid contact with various inorganic powders, and excellent heat resistance and corrosion resistance with little reaction at high temperatures. Next, regarding the second thermal shock resistance, since ZrB2 alone in the inner layer is not sufficient, a ZrB2 pipe is used as a core and the surrounding material is C-MgO1C- which is a material containing carbon with excellent thermal shock resistance.
A120. , C-Zr0. The outer layer is formed by filling and disposing powder of raw materials such as high quality, and this is unfired (heat-dried) or heated to make the inner layer and outer layer denser.
It prevents contact between the outer periphery of the inner layer and the molten metal without creating a gap between the outer layers, greatly improving the heat resistance of the entire nozzle and extending its life by more than 1.5 times that of conventional nozzles. It is something.

In other words, if the inner layer and the outer layer are formed separately and simply fitted together, when the inner layer and the outer layer are actually immersed in molten metal and used, the inner layer of ZrB2 and the outer layer of C-Mg will be separated.
A gap is created between the layers with O, etc.

Even if ZrB is used, its effectiveness is greatly reduced because the inner layer is worn away from the outer periphery due to the penetration of molten metal into that area. Thirdly, the inner layer ZrB is a hard material with extremely high Vickers hardness, and is not easily worn even when a large amount of hard inorganic powder is flowed, making it suitable as a powder injection nozzle.

[Brief explanation of drawings]

FIG. 1 shows an example of the curved shape of the composite nozzle of the present invention.
A) is a cross-sectional view, and (b) is a side view. In the drawing, 1 is 7. r B , a solid inner layer, 2 a carbon-containing outer layer.

Claims (2)

[Claims] (1) A nozzle for blowing gas or gas and powder into molten metal, and an inner layer mainly made of ZrB_2 refractory;
A composite nozzle comprising an outer layer of a carbon-containing refractory whose inner circumference is directly adhered to the outer circumference of the inner layer. (2) A nozzle for injecting gas or gas and powder into molten metal, the inner layer is a cylindrical sintered body mainly made of ZrB_2 refractory, and the outer layer is carbon-containing refractory powder granules. Fill it to form an outer layer, dry it in an unfired state,
Alternatively, a method for producing a composite nozzle, which comprises heating and baking to a predetermined temperature after drying to bring the inner circumference of the outer layer into direct contact with the outer circumference of the inner layer.