JPH0674426A - Torch for gas cutting made of sintered compact of silicon nitride or sialon - Google Patents

Abstract

PURPOSE:To provide a torch for gas cutting by which sputter and adhesion of foreign metals can be reduced and which has high wear resistance and heat resistance, and enables consecutive use for many hours. CONSTITUTION:A torch for gas cutting comprises a sintered compact of silicon nitride or sialon. The sindered body contains an oxide as a sintering assistant, and 80wt.% or more silicon nitride or sialon of having a Z value of more than zero and less than 3.5. The sintered compact has a bulk density of 2.8g/cm<3> or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crater member of a gas cutting device, and more particularly to a crater member used in a gas cutting device for cutting a plate material, a pipe material, a rod material and the like.

[0002]

2. Description of the Related Art Conventionally, various cutting devices such as gas cutting, laser cutting, and plasma cutting have been used as cutting devices for plate materials, pipe materials, etc. Among them, the crater of the gas cutting device is usually heat-resistant. , Brass products with excellent workability are used.

In gas cutting, spatter, foreign metal, etc. adhere to the cutting crater, and a cleaning tool such as a stainless steel needle is conventionally used to remove the adhered matter. At the time of this removal, there is a problem that the brass crater member is worn and scratched by the cleaning tool used, and the crater life is shortened.

As a countermeasure against this, for example, Japanese Patent Laid-Open No. 52-70.
Although a crater member made of stainless steel is proposed in Japanese Patent No. 965, although it is superior in abrasion resistance to a crater member made of brass, no dramatic improvement is seen.

Further, if the cutting is carried out for a long time, the cutting performance is hindered by the spatter deposited on the crater, the foreign metal, etc., which makes continuous operation using an automatic device difficult for a long time. During continuous operation, there is a problem that the crater portion is deformed due to thermal strain, and a stable cutting air flow cannot be obtained.

In recent years, for example, Japanese Patent Laid-Open No. 61-19021.
As proposed in Japanese Patent Laid-Open No. 2 (1994), it has been attempted to use fine ceramics containing oxide-based ceramics such as alumina and zirconia, which have excellent wear resistance. In addition, it is difficult to remove, and the problem has not been solved yet.

[0007]

The problem to be solved by the present invention is to obtain a member for a gas cutting tip which is suitably used in a gas cutting apparatus and which satisfies the following items during a cutting operation.

Less spatter and foreign metal adhesion.

Excellent wear resistance and heat resistance.

Being able to be used for a long time.

[0011]

In view of the above situation, the present inventor has conducted various studies on members for gas cutting craters, and as a result, it has been found that a silicon nitride-based or sialon-based sintered body satisfies the demand. Heading out, the present invention has been completed.

That is, the member for gas cutting crater of the present invention contains an oxide as a sintering aid, and contains silicon nitride or Z.
Substantially 8 sialons with a value greater than 0 and less than 3.5
Contains 0% by weight or more and has a bulk density of 2.8 g
/ Cm ³ or more.

If the content of silicon nitride or sialon in the silicon nitride sintered material is less than 80% by weight, it is impossible to obtain a sintered material having sufficient strength and wear resistance as a crater member.

The Z value of sialon must be greater than 0 and less than 3.5. When the Z value is 3.5 or more, the strength, toughness and wear resistance of the sialon sintered body are remarkably deteriorated. Not suitable for.

The bulk density of the sintered body is 2.8 g / c.
When m ³ or more is required and it is less than 2.8 g / cm ³ , many pores are present in the sintered body to form a porous structure, and the strength, toughness, and wear resistance are significantly reduced. Further, if it has a porous structure, spatter or the like is likely to adhere, and the advantages of silicon nitride or sialon described above cannot be utilized.

The member for gas cutting crater having the above structure is manufactured as follows. First, in a silicon nitride powder having a particle size of less than 3 μm after pulverization, Al was used as a sintering aid.
₂ O ₃ , Y ₂ O ₃ , AlN, etc. are added so that the total amount is less than 20% by weight, and this mixture is prepared by a mixing mill such as a pot mill, a ball mill containing water or a solvent, or an attritor. . At that time, a dispersant for the slurry, a binder for dry molding and the like are added in appropriate amounts to obtain a molding slurry. The obtained slurry is dried and then formed into a predetermined shape by a known molding method for ceramic products such as uniaxial press molding, isostatic press molding, injection molding, and casting molding, and processed as required. The molded body is degreased in the next step,
As it is, it is degreased and sintered in the sintering process. The firing temperature is 1600 ° C to 1850 ° C in a nitrogen atmosphere. in this case,
At 1600 ° C. or lower, the predetermined density cannot be reached, and at 1850 ° C. or higher, silicon nitride is decomposed. The pressure in the furnace during firing is atmospheric pressure or a pressure of 10 MPa, whereby a sintered body having a bulk density of 2.8 g / cm ³ or more can be obtained. If necessary, the sintered body is subjected to shape processing, and the surface is finished smooth by grinding, free abrasive grain processing, or the like.

The crater member may be made of the above silicon nitride or sialon sintered material as a whole,
Especially, only the part that becomes high temperature is composed of silicon nitride or sialon sintered material, and this is fitted to metal hardware etc.,
Alternatively, they can be formed by pasting.

[0018]

The silicon nitride and sialon constituting the refractory for gas cutting crater of the present invention are covalently bonded substances,
A sintered body containing 80% by weight or more of this has excellent mechanical properties such as strength and abrasion resistance, as compared with other materials such as alumina. The bulk density is 2.8 g / cm ^3.
Due to the above-mentioned denseness, the adhesion of spatter to the surface is prevented, and the adhered adhered matter can be easily removed.

[0019]

【Example】

Example 1 Silicon nitride powder having an average particle size of 0.3 μm, 3% by weight of Al ₂ O ₃ having a particle size of 1 μm or less, 5% of Y ₂ O _{3 and 2} % by weight of AlN.
Was dried with a spray dryer to obtain a molding powder. This powder was press-molded, and was subjected to 1750 in a nitrogen atmosphere.
Firing at 5 ° C. for 5 hours gave a sialon sintered body having a bulk density of 3.23 g / cm ³ . This sintered body was processed into a shape to form a cutting oxygen passage portion, which was combined with a brass mold to manufacture a gas cutting crater.

Table 1 shows the results of the cutting test performed on the above-mentioned example product and the brass comparative example.

[Table 1] As is clear from the table, in the product of this example, the amount of spatter adhered was extremely small and a life of 500 hours or more was obtained. Further, the spatter adhered could be easily removed with a cleaning tool.

Example 2 Silicon nitride powder and other sintering aids and molding aids were wet-dispersed and pulverized at a weight ratio shown in Table 2 and dried by a spray dryer to give a molding powder. Got This powder body is press-molded, and it is heated at 1750 ° C. in a nitrogen atmosphere for 5 minutes.
It was fired for a time to obtain a predetermined sintered body. This sintered body was processed into a shape to prepare a sample for a sputter adhesion test. The obtained sample was used for a sputter adhesion test and a damage test for removing the adhered spatter using a cleaning tool. In addition, from the sintered body obtained by the same method, 4 × 3 × 40
After processing the mm sample, a bending test was performed according to the JIS standard. Samples 1 to 3 are samples having the composition within the scope of claims, and Samples 4 and 5 are comparative products that do not satisfy the condition of 1 or more. Table 2 shows the results, and the results for other ceramics for comparison.

[0022]

[Table 2] As is clear from Table 2, even if the silicon nitride-based or sialon-based sintered body does not satisfy the above conditions,
As with other ceramic materials, adhesion and damage during cleaning pose problems, but spatter is difficult to adhere to with the claimed silicon nitride-based or sialon-based sintered body, and even if adhered, the sintered body will be damaged. Since it can be removed without doing so, it is understood that it is suitable as a crater member.

Example 3 Next, a sintered body equivalent to the sialon of Example 1 was prepared with φ10.
After processing into a sample of × 10 mm, the coefficient of thermal expansion was measured with a dilatometer. The results are shown in Table 3. Other materials were also measured for comparison.

[0024]

[Table 3] As is clear from Table 3, the crater member of the present embodiment has a thermal expansion of about 1/10 as compared with the conventional products made of stainless steel and brass, and 1 / compared with alumina and zirconia. You can see that it is as small as 3. Therefore, the crater member using the sialon of the example has little thermal strain in the crater portion during the cutting operation, and can maintain a stable cutting air flow for a long time.

[0025]

According to the present invention, the following effects can be obtained.

(1) By using the silicon nitride-based or sialon-based sintered body of the present invention in the crater of the cutting device, wear resistance and heat resistance are improved, and spatter and foreign metal are less likely to adhere. It enables long-term continuous operation.

(2) Spatters and foreign metals attached by the cutting work can be easily removed without damaging the members.

(3) Compared with a metal crater made of brass or stainless steel, thermal deformation is less and stable cutting air flow can be obtained for a long time.

Claims (1)

[Claims] 1. A sintering aid containing an oxide, containing substantially 80% by weight or more of silicon nitride or sialon having a Z value of more than 0 and less than 3.5 and having a bulk density of 2 or more. A member for a gas cutting crater, which is made of a silicon nitride material or a sialon material sintered body, characterized by having a content of at least 8 g / cm ³ .