JP7364944B2 - Nozzle and nozzle manufacturing method - Google Patents

Description

The present invention relates to a nozzle used for metal casting, and a method for manufacturing the nozzle.

In casting molten metal, molten metal is injected into a mold or the like from a container such as a ladle or tundish through a molten metal casting nozzle (hereinafter simply referred to as "nozzle"). Nozzles used in this application are often formed from carbon-containing refractories that are resistant to spalling. For example, in Japanese Patent Application Laid-open No. 11-277196 (Patent Document 1), a cylindrical member made of refractory is covered with a metal case for the purpose of suppressing cracks in the refractory and improving sealing performance from the outside air. discloses a nozzle in which a gap between a cylindrical member and a metal case is filled with refractory mortar.

On the other hand, since the nozzle inner hole is rapidly heated with the flow of molten metal, compressive stress is generated in the circumferential direction of the nozzle inner hole, and tensile stress is generated in the circumferential direction of the nozzle outer periphery. Since stress occurs in opposite directions on the inner hole side and the outer circumference side, radial cracks may occur from the outer circumference toward the inner hole. Furthermore, as the nozzle inner hole becomes negative pressure as the molten metal flows, air may be sucked through the cracks. This air causes the refractory material in the cylindrical member to oxidize, which may cause the nozzle to deteriorate. In view of such problems, Japanese Patent Laid-Open No. 2010-023057 (Patent Document 2) discloses a molten metal casting nozzle in which a crack plugging material is applied to a portion of a cylindrical member that is not covered by a metal case. ing.

Japanese Patent Application Publication No. 11-277196 Japanese Patent Application Publication No. 2010-023057

However, even with the technique of Patent Document 2, oxidation of the refractory of the cylindrical member could not be sufficiently suppressed in some cases. In particular, oxidation was sometimes observed even in areas where the cylindrical member was covered with the metal case.

Therefore, there is a need to realize a nozzle that can further suppress oxidation of refractories compared to conventional techniques.

The nozzle according to the present invention includes a cylindrical body, a metal case that at least partially houses the cylindrical body, and a refractory mortar layer between the cylindrical body and the metal case, The body includes a cylindrical member made of a refractory material, and an antioxidant layer that covers at least a portion of a portion of the cylindrical member accommodated in the metal case, and the antioxidant layer includes: It is characterized by containing an antioxidant that melts in the temperature range in which the nozzle is used .

Further, the method for manufacturing a nozzle according to the present invention includes a step of forming a cylindrical body having a cylindrical member made of a refractory material and an antioxidant layer covering at least a part of the cylindrical member; forming a refractory mortar layer that at least partially surrounds the antioxidant layer; and housing the cylindrical body in a metal case , wherein the antioxidant layer melts in the nozzle operating temperature range. In the step of forming the cylindrical body, the antioxidant layer is formed so as to cover at least a part of a portion of the cylindrical body accommodated in the metal case. shall be.

Conventionally, in areas where a cylindrical refractory member is housed in a metal case, it has been thought that oxidation of the refractory is suppressed by blocking air from the metal case. The general idea was that the contained parts did not need to be coated with antioxidants. The present inventors made detailed observations of cases where oxidation was observed even where the cylindrical member was covered with a metal case, and found that a refractory mortar layer was filled between the cylindrical member and the metal case. It was thought that when the refractory mortar layer is exposed to air, the pores in the refractory mortar layer act as air passages, allowing air to reach the cylindrical member and lead to oxidation of the refractory. Based on this idea, we came up with the idea of providing an antioxidant layer that covers at least a portion of the portion of the cylindrical member housed in the metal case, and completed the present invention. According to the above configuration, oxidation of the refractory can be further suppressed compared to conventional nozzles. Particularly, parts covered with a metal case are less susceptible to deterioration due to oxidation.

Hereinafter, preferred embodiments of the present invention will be described. However, the scope of the present invention is not limited to the preferred embodiments described below.

In one embodiment of the nozzle according to the present invention, it is preferable that the cylindrical body further includes a water repellent layer that covers at least a portion of the antioxidant layer.

In conventional techniques such as Patent Document 2, oxidation of the refractory may be observed even in areas where an antioxidant has been applied. The present inventors have observed this aspect of oxidation in detail and found that when refractory mortar comes into contact with the surface of a cylindrical member coated with an antioxidant, the refractory mortar absorbs the antioxidant, causing the cylindrical member to It was thought that the antioxidant effect on the parts would be impaired. Based on this idea, the present invention was completed based on the idea of providing a water repellent layer that covers at least a portion of the antioxidant layer. According to this configuration, since the antioxidant effect of the antioxidant is less likely to be impaired when forming the refractory mortar layer, even more antioxidant effect can be obtained.

In one aspect of the nozzle according to the present invention, it is preferable that the water repellent layer contains at least one of graphite, carbon black, and silicon carbide.

According to this configuration, a higher antioxidant effect can be achieved than when the water repellent layer contains other components.

Further features and advantages of the invention will become clearer from the following description of exemplary and non-limiting embodiments, written with reference to the drawings.

FIG. 2 is a cross-sectional view of a nozzle according to an embodiment.

Embodiments of a nozzle and a nozzle manufacturing method according to the present invention will be described with reference to the drawings. Below, an example will be described in which the nozzle according to the present invention is applied to a nozzle 1 used for casting metal.

[Nozzle configuration]
The nozzle 1 according to this embodiment includes a cylindrical body 2 made of refractory, a metal case 3, and a refractory mortar layer 4 (FIG. 1). The metal case 3 at least partially houses the cylindrical body 2, and a refractory mortar layer 4 is filled between the cylindrical body 2 and the metal case 3. In this embodiment, the entire cylindrical body 2 is housed in a metal case 3, and the entire side surface of the cylindrical body 2 is covered with the metal case 3. Correspondingly, the total length of the cylindrical body 2 and the total length of the metal case 3 are substantially equal.

The cylindrical body 2 includes a cylindrical member 21 made of a refractory material, an antioxidant layer 22 that covers the cylindrical member 21, and a water repellent layer 23 that covers the antioxidant layer 22. The refractory material forming the cylindrical member 21 is not particularly limited as long as it is a refractory material commonly used in this field. The refractory forming the cylindrical member 21 may be, for example, a carbon-containing refractory, including oxide raw materials such as alumina, magnesia, spinel, and zirconia, non-oxide raw materials such as silicon carbide, graphite, coke, and carbon black. , carbon raw materials such as coltar pitch, etc. may be included in the refractory.

In this embodiment, the entire side surface of the cylindrical member 21 is covered with an antioxidant layer 22 containing an antioxidant. The antioxidant contained in the antioxidant layer 22 is not particularly limited as long as it is an antioxidant commonly used in this field. Such antioxidants include, for example, Al ₂ O ₃ 20% by mass or more and 30% by mass or less, SiO ₂ 5% by mass or more and 15% by mass or less, Na ₂ O and K ₂ O in a total of 15% by mass or more and 25% by mass or less, P ₂ O ₅ The antioxidant may have a composition of 20% by mass or more and 40% by mass or less. The antioxidant exhibits its antioxidant effect through a mechanism of action: it melts into a fluid state in the operating temperature range of the nozzle 1, and fills cracks generated in the cylindrical body 2. Therefore, the composition of the antioxidant can be determined in consideration of the operating temperature range of the nozzle 1.

It is preferable that the thickness of the antioxidant layer 22 is 0.1 mm or more, since the antioxidant effect is particularly easily expressed. The thickness of the antioxidant layer 22 is more preferably 0.5 mm or more. Further, it is preferable that the thickness of the antioxidant layer 22 is 5 mm or less because it is easy to obtain a uniform antioxidant layer 22. The thickness of the antioxidant layer 22 is more preferably 3 mm or less, and even more preferably 1 mm or less.

In this embodiment, the entire antioxidant layer 22 is further covered with a water repellent layer 23 containing a water repellent. The water repellent contained in the water repellent layer 23 is not particularly limited as long as it is a water repellent commonly used in this field. Such water repellents include, for example, a slurry of one or more selected from graphite, carbon black, boron carbide, silicon carbide, alumina, and silica with an alkaline silicate solution, and petroleum-based water repellents. , a fluororesin water repellent, a silicone resin water repellent, and the like. Preferably, water repellent layer 23 contains at least one of graphite, carbon black, and silicon carbide.

By covering the antioxidant layer 22 with the water repellent layer 23, the reaction between the water contained in the fireproof mortar layer 4 and the antioxidant in the antioxidant layer 22 can be suppressed, thereby preventing the antioxidant effect from being impaired. It becomes difficult. It is preferable that the thickness of the water repellent layer 23 is 0.1 mm or more, since the water repellent effect is particularly easily exhibited and the antioxidant effect of the antioxidant layer 22 is easily maintained. The thickness of the water repellent layer 23 is preferably 0.5 mm or more. Further, it is preferable that the thickness of the water repellent layer 23 is 5 mm or less because it is easy to obtain a uniform water repellent layer 23. The thickness of the water repellent layer 23 is more preferably 3 mm or less, and even more preferably 1 mm or less.

The metal case 3 is a metal case that houses the cylindrical body 2. The metal material constituting the metal case 3 is not particularly limited as long as it is normally used in the art as a metal material constituting the metal case, and may be, for example, iron, stainless steel, aluminum, copper, or the like. Moreover, the metal case 3 can be formed by a known metal processing technique (press molding, etc.).

The refractory mortar layer 4 is a layer in which refractory mortar is filled between the cylindrical body 2 and the metal case 3 for the purpose of improving filling performance. The refractory mortar constituting the refractory mortar layer 4 is not limited to a refractory mortar commonly used in this field, and may be, for example, a refractory mortar whose main component is an oxide such as alumina or silica. In particular, in conventional technology, when refractory mortar with relatively high porosity is used, air reaches the refractory through the pores, which causes oxidation and damage to the refractory. In this embodiment, since the cylindrical member 21 is coated with the antioxidant layer 22, damage to the refractory material constituting the cylindrical member 21 is suppressed regardless of the porosity of the refractory mortar layer 4.

[Nozzle manufacturing method]
The method for manufacturing the nozzle 1 according to the present embodiment includes a step of forming a cylindrical body 2, a step of forming a refractory mortar layer 4 surrounding the antioxidant layer 22 of the cylindrical body 2, and a step of forming the cylindrical body 2. and a step of accommodating it in a metal case 3. The process of forming the cylindrical body 2 includes a step of forming a cylindrical member 21 made of refractory material, a step of coating the cylindrical member 21 with an antioxidant to form an antioxidant layer 22, and a step of coating the cylindrical member 21 with an antioxidant to form an antioxidant layer 22. coating the layer 22 with a water repellent agent to form a water repellent layer 23;

As the step of forming the cylindrical member 21 made of refractory material, a known method for forming a member made of refractory material can be applied. That is, a step of kneading the above raw materials together with a binder, a step of molding the kneaded raw materials into a desired shape by a method such as compression molding to obtain a preform, a step of drying the preform, and a step of preforming after drying. The cylindrical member 21 may be formed by a process including firing the body.

The step of forming the antioxidant layer 22 can be performed, for example, by applying an antioxidant to the surface of the cylindrical member 21. The method for applying the antioxidant is to form a slurry by adding an auxiliary agent such as water to the antioxidant, and apply the slurry to the surface of the cylindrical body 2 using a known tool such as a brush or a sprayer. A method is illustrated. The concentration of the antioxidant in the slurry formed at this time is not particularly limited, but may be, for example, 50% by mass or more and 90% by mass or less. Furthermore, the cylindrical member 21 coated with the antioxidant may be heat-treated. The temperature of the heat treatment in this case may be, for example, 500° C. or higher.

The step of forming the water repellent layer 23 can be performed by the same method as the step of forming the antioxidant layer 22. That is, a method of applying a slurry containing a water repellent agent to the surface of the antioxidant layer 22 using a known tool such as a brush or a sprayer is exemplified. The concentration of the water repellent in the slurry formed at this time is not particularly limited, but may be, for example, 50% by mass or more and 90% by mass or less.

The step of forming the refractory mortar layer 4 can be performed, for example, by a method of applying refractory mortar to the surface of the cylindrical body 2 (ie, the water repellent layer 23). Further, the step of housing the cylindrical body 2 in the metal case 3 can be carried out, for example, by inserting the cylindrical body 2 into the metal case 3 which is previously formed into a predetermined shape. When this procedure is carried out, after forming the refractory mortar layer 4 on the outside of the cylindrical body 2, the cylindrical body 2 and the refractory mortar layer 4 are inserted into the metal case 3 as one body.

[Other embodiments]
Finally, other embodiments of the nozzle and nozzle manufacturing method according to the present invention will be described. Note that the configurations disclosed in each of the embodiments below can be applied in combination with the configurations disclosed in other embodiments as long as no contradiction occurs.

In the embodiment described above, the configuration in which the entire cylindrical body 2 is housed in the metal case 3 has been described as an example. However, in the nozzle according to the present invention, it is sufficient that the cylindrical body is at least partially housed in the metal case. Which part of the cylindrical body is accommodated in the metal case is determined in consideration of the intended use of the nozzle.

In the above embodiment, the entire side surface of the cylindrical member 21 is covered with the antioxidant layer 22 as an example. However, in the nozzle according to the present invention, it is not necessary that the entire side surface of the cylindrical member is coated with the antioxidant layer, and at least a part of the portion of the cylindrical member accommodated in the metal case is coated with the antioxidant layer. It is sufficient if it is covered with a layer.

In the above embodiment, the entirety of the antioxidant layer 22 is further covered with the water repellent layer 23. However, in the nozzle according to the present invention, the water repellent layer may not be provided. Furthermore, even when a water repellent layer is provided, the entire antioxidant layer does not need to be covered with the water repellent layer, and at least a portion of the antioxidant layer is covered with the water repellent layer. All you have to do is stay there.

Note that when manufacturing a nozzle without a water repellent layer, the step of forming the water repellent layer is omitted in the step of forming the cylindrical body.

Regarding other configurations, it should be understood that the embodiments disclosed in this specification are illustrative in all respects, and the scope of the present invention is not limited thereby. Those skilled in the art will easily understand that modifications can be made as appropriate without departing from the spirit of the present invention. Therefore, other embodiments that are modified without departing from the spirit of the present invention are naturally included within the scope of the present invention.

In the following, the present invention will be further explained by showing examples. Note that the following examples do not limit the present invention.

〔reagent〕
(Antioxidant)
As the antioxidant, a phosphoric acid glass glaze containing 23% by mass of Al ₂ O ₃ , 9% by mass of SiO ₂ , 20% by mass of Na ₂ O and K ₂ O in total, and 30% by mass of P ₂ O ₅ was used.

(water repellent)
In Examples 2 to 10, a slurry in which the inorganic substances shown in each Example were dispersed in an aqueous potassium silicate solution was used as a water repellent. In each example, the concentration of the inorganic substance in the slurry was 30% by mass. In Example 11, a petroleum-based water repellent was used as the water repellent.

(Fireproof mortar)
As a refractory mortar, one containing 3% by mass of Al ₂ O ₃ and 86% by mass of SiO ₂ was used. Note that the remainder is an alkali metal, an alkaline earth metal, etc.

[Creating a nozzle]
(Example 1)
A nozzle without a water repellent layer was created according to the embodiment described above except that the step of forming the water repellent layer was omitted. The thickness of the antioxidant layer was 1 mm. The shape of the nozzle was 305 mm in total length, 155 m in outer diameter, and 50 mm in inner diameter.

(Examples 2 to 5)
A nozzle having a water repellent layer was created according to the embodiment described above. The shape of the nozzle was the same as in Example 1. Graphite was used as an inorganic substance in the water repellent. The thickness of the antioxidant layer was 1 mm. The thickness of the water repellent layer was 0.5 mm in Example 2, 1 mm in Example 3, 3 mm in Example 4, and 5 mm in Example 5.

(Example 6)
A nozzle having a water repellent layer was created according to the embodiment described above. The shape of the nozzle was the same as in Example 1. Carbon black was used as an inorganic substance in the water repellent. The thickness of the antioxidant layer was 1 mm, and the thickness of the water repellent layer was 1 mm.

(Example 7)
A nozzle having a water repellent layer was created according to the embodiment described above. The shape of the nozzle was the same as in Example 1. Boron carbide was used as an inorganic substance in the water repellent. The thickness of the antioxidant layer was 1 mm, and the thickness of the water repellent layer was 1 mm.

(Example 8)
A nozzle having a water repellent layer was created according to the embodiment described above. The shape of the nozzle was the same as in Example 1. Silicon carbide was used as the inorganic substance in the water repellent. The thickness of the antioxidant layer was 1 mm, and the thickness of the water repellent layer was 1 mm.

(Example 9)
A nozzle having a water repellent layer was created according to the embodiment described above. The shape of the nozzle was the same as in Example 1. Alumina was used as an inorganic substance in the water repellent. The thickness of the antioxidant layer was 1 mm, and the thickness of the water repellent layer was 1 mm.

(Example 10)
A nozzle having a water repellent layer was created according to the embodiment described above. The shape of the nozzle was the same as in Example 1. Silica was used as an inorganic substance in the water repellent. The thickness of the antioxidant layer was 1 mm, and the thickness of the water repellent layer was 1 mm.

(Example 11)
A nozzle having a water repellent layer was created according to the embodiment described above. The shape of the nozzle was the same as in Example 1. A petroleum-based water repellent was used as the water repellent. The thickness of the antioxidant layer was 1 mm, and the thickness of the water repellent layer was 1 mm.

(Comparative example)
A nozzle without an antioxidant layer and a water repellent layer was created according to the embodiment described above, except that the step of forming an antioxidant layer and the step of forming a water repellent layer were omitted. The shape of the nozzle was the same as in Example 1.

〔Evaluation methods〕
After thoroughly drying each nozzle of Examples and Comparative Examples, they were heated in an oxidizing atmosphere at 1000° C. for 10 hours. After the heated sample was allowed to cool to room temperature, the sample was cut and the cross section was observed using an optical microscope. The oxidation resistance of each of the Examples and Comparative Examples was evaluated on the following four levels A to D based on the observation results of the cross section.
A: Almost no oxidized layer is seen in the cross section.
B: An oxidized layer can be found by careful observation.
C: The oxidized layer is reduced compared to the comparative example (level D).
D: An oxidized layer is clearly seen in the cross section. (Comparative example)

Note that the oxidized layer in the cross section was identified by observing the thickness of the carbon disappearing layer in the cut surface of the sample.

〔result〕
Table 1 shows the evaluation results of Examples and Comparative Examples. In all Examples, a reduction in the oxidized layer was observed compared to the Comparative Example in which no antioxidant layer was provided. Further, in Examples 2 to 11 in which a water repellent layer was provided, a further reduction in the oxidized layer was observed compared to Example 1 in which a water repellent layer was not provided. In particular, Examples 2, 3, 6, 7, and 8 in which the thickness of the water repellent layer was 1 mm or less by using a water repellent containing graphite, carbon black, boron carbide, or silicon carbide were the most A remarkable oxidation inhibitory effect was observed.

Table 1: Examples and comparative examples

INDUSTRIAL APPLICATION This invention can be utilized for the nozzle provided for metal casting, for example.

1 Nozzle 2 Cylindrical body 21 Cylindrical member 22 Antioxidant layer 23 Water repellent layer 3 Metal case 4 Fireproof mortar layer

Claims (4)

comprising a cylindrical body, a metal case that at least partially houses the cylindrical body, and a refractory mortar layer between the cylindrical body and the metal case,
The cylindrical body has a cylindrical member made of a refractory material, and an antioxidant layer that covers at least a portion of a portion of the cylindrical member accommodated in the metal case,
The antioxidant layer is a nozzle containing an antioxidant that melts in a temperature range in which the nozzle is used . The nozzle according to claim 1, wherein the cylindrical body further includes a water repellent layer covering at least a portion of the antioxidant layer. The nozzle according to claim 2, wherein the water repellent layer contains at least one of graphite, carbon black, and silicon carbide. forming a cylindrical body having a cylindrical member made of a refractory material and an antioxidant layer covering at least a portion of the cylindrical member;
forming a refractory mortar layer that at least partially surrounds the antioxidant layer;
accommodating the cylindrical body in a metal case,
The antioxidant layer contains an antioxidant that melts in a temperature range in which the nozzle is used,
A method for manufacturing a nozzle, wherein in the step of forming the cylindrical body, the antioxidant layer is formed so as to cover at least a part of a portion of the cylindrical body accommodated in the metal case.

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