KR101364380B1 - Silicon nitride die for hot extention and a manufaturing method thereof - Google Patents

Abstract

Disclosed is a method for manufacturing a silicon nitride extrusion die comprising: a step (a) of manufacturing raw materials through a spray dry process by adding 80 wt% of silicon nitride (Si_3N_4) powder, 9 wt% of yttria (Y_2O_3) and 11 wt% of aluminum nitride (AIN); a step (b) of manufacturing a press molded product by pressing a mold after the raw materials are charged in the mold; a step (c) of pre-sintering the molded product at 600-800°C for 15 hours; a step (d) of processing the pre-sintered molded product to the shape of a tip; a step (e) of pressure-sintering the processed tip at 1,740°C for 2-3 hours with the 100-200 atmospheric pressure of argon (Ar); a step (f) of completing a silicon nitride tip by processing the outer diameter, the inner diameter, and the thickness of the tip passed the step (e) using a diamond grindstone; a step (g) of preparing a metal case having the outer diameter 0.1% smaller than the outer diameter of the silicon nitride tip by rough-machining hot tool steel (skd61) having the HRC 48-52 of a thermal treatment hardness; and a step (h) of shrink-fitting the completed silicon nitride tip in the metal case heated at 400-450°C. [Reference numerals] (AA) Metal case machining process; (BB) Shrink fitting process; (S1) Raw material manufacturing process; (S2) Molded product manufacturing process; (S3) Pre-sintering process; (S4) Tip forming process; (S5) Pressure sintering process; (S6) Silicon nitride tip completing process

Description

Silicon nitride extrusion die and manufacturing method thereof {Silicon Nitride Die for Hot Extention and a manufaturing method

The present invention relates to a silicon nitride extrusion die which can be applied to a silicon nitride brass hot extrusion process and a method for manufacturing the same.

In general, building materials and metal parts have been manufactured using metal dies such as cemented carbide, nickel, tool steel, or cobalt base alloys. These products are extruded by high temperature and high pressure extrusion when manufactured using conventional metal dies. Due to problems such as the reaction between water and the inner diameter of the die, friction, and abrasion, the die should be removed after 2-3 extrusions, and then re-installed after undergoing internal polishing, preheating, etc.

Due to the short life of the metal die, there were many problems such as frequent interruption of work and replacement of new die, consumption of many workers, poor surface of extruded products, bad dimension of extruded products, and preparation of many stock dies.

In order to solve such a problem, a ceramic extrusion die which is shrinked with a ceramic insert in a metal die cast, a zirconia extrusion die is disclosed in Korean Patent Registration No. 0149931. The disclosed zirconia extrusion die is manufactured by shrinking a zirconia insert obtained by sintering and heat-treating a powder in which monomagnesia is partially added to monoclinic zirconia powder into a metal die case, and using the excellent zirconia-specific toughness to solve the problems of conventional metal dies. Somewhat solved.

However, the zirconia extrusion die of the prior art has a problem in that the surface roughness of the product is poor due to the problem of deterioration of life due to micro cracks and breakage occurring at the beginning of the extrusion process and low lubrication property with brass as an extruded material. It is not applicable to the extrusion process.

In addition, the high temperature toughness and high temperature hardness is not good, it can not be used at high and high pressure extrusion load, and even though there is a risk of breakage at the initial stage of extrusion due to hot brittleness, it has not been developed an extrusion die that can replace it until now.

An object of the present invention is to solve the problems of the above-described ceramic extrusion die of the prior art, it is excellent in high temperature toughness, high temperature hardness, can withstand high temperature of 900 ℃ or higher, extrusion load of 3,000 tons or more, The present invention provides a silicon nitride extrusion die and a method for manufacturing the same, which have excellent lubricity to improve the quality of the surface of the extrudate and the life of the die.

Silicon nitride extrusion die of the present invention, a metal case; And silicon nitride (Si₃N₄) tips shrink-fitted into the metal casing, wherein the silicon nitride tips include 80 wt% of silicon nitride (Si₃N₄) powder, 9% of Y₂O₃, and aluminum nitride (Aluminum Nitride). , AlN) 11%.

The silicon nitride tip, 80% by weight of silicon nitride (Si₃N₄) powder, 9% of Y 2 O₃ and 11% of aluminum nitride (Aluminum Nitride, AlN) were added to prepare a raw material by a spray drying process. After filling into a mold to manufacture a press-formed product, it is preferable that the molded product is pre-sintered at 600 ° C to 800 ° C for 15 hours, and then pressurized and sintered argon (Ar) at 1,740 ° C for 2-3 hours.

In addition, in the method for producing a silicon nitride extrusion die of the present invention, (a) 80% by weight of silicon nitride (Si₃N₄) powder, 9% of Y 2 O₃ and 11% of aluminum nitride (Aluminum Nitride, AlN) are added to the spray drying process. Preparing a raw material; (b) preparing a press-molded product by filling the raw material into a mold and then pressing; (c) pre-sintering the molded product at 600 ° C. to 800 ° C. for 15 hours; (d) processing the presintered molded article into a tip shape; (e) pressure sintering the processed tip at 1,740 ° C. for 2-3 hours at 100-200 atmospheres of argon (Ar); (f) processing the outer diameter, the inner diameter, and the thickness of the tip that has passed through the step (e) using diamond abrasive stone to complete the silicon nitride tip; (g) roughing the hot-hole oral cavity (skd61) having a heat treatment hardness of HRC 48-52 to less than 0.1% of the outer diameter of the silicon nitride tip to prepare a metal case; And (h) shrinking the finished silicon nitride tip into a metal case heated to 400 -450 ° C.

According to the above, the silicon nitride extrusion die of the present invention has excellent high temperature toughness and high temperature hardness, and can withstand high temperature of 900 ° C or higher and extrusion load of 3,000 tons or more, and is excellent in extruded material and lubricity, so that the surface quality and die of the extruded material are excellent. It has the advantage of long life and greatly improved brittleness.

In addition, in the extrusion die manufacturing method of the present invention, 80% by weight of silicon nitride (Si₃N₄) powder, 9% of Y 2 O₃ and 11% of aluminum nitride (Aluminum Nitride, AlN) are added to prepare a raw material by spray drying. After pressing the pre-sintered molded product at 600 ℃ to 800 ℃ for 15 hours, and then pressurized and sintered argon (Ar) at 1,740 ℃ for 2-3 hours, the inherent characteristics of the ceramic material The properties are greatly improved brittleness, there is an effect that can produce a silicon nitride extrusion die having high strength and hardness, heat shock resistance.

1 is a cross-sectional view of a silicon nitride extrusion die according to an embodiment of the present invention,
Figure 2 is a manufacturing process flow chart for explaining the silicon nitride extrusion die manufacturing method according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail to the concrete inventive concept.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Like reference numerals are used for like elements in describing each drawing.

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in between. Should be.

On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise.

In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Hereinafter, a silicon nitride extrusion die 10 according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Silicon nitride extrusion die 10 according to an embodiment of the present invention, the metal case 12 and a double, consisting of a silicon nitride (Si₃N ₄) tip 20 is shrink-fit (shrink fitting) to the metal case 12 Has a structure.

The metal case 12 is a portion for supporting the silicon nitride tip 20, and is preferably made of a hot hole mouth (SKD61) material. The inner diameter of the first hole 15 of the metal case 12 is 0.1% smaller than the outer diameter of the silicon nitride tip 20 and then shrinks with the silicon nitride tip 20. The outer surfaces 13 and 14 of the metal case 12 have an inclined structure extending upward by 2.5 ° with respect to the vertical line, and the inner diameter d3 of the second hole 16 of the metal case 12 is the silicon nitride tip 20. 8 mm larger than the inner diameter d1 of the second hole 18.

The silicon nitride tip 20 is composed of 80% by weight of silicon nitride (Si 3 N₄) powder, 9% of Y 2 O 3, and 11% of aluminum nitride (AlN). The inner diameter of the first hole 17 of the silicon nitride tip 20 is preferably configured to be 5 mm larger than the inner diameter d1 of the second silicon nitride hole 18 (d2).

Hereinafter, a method of manufacturing a silicon nitride extrusion die according to an embodiment of the present invention will be described in detail with reference to FIG. 2.

First, 80 wt% of silicon nitride (Si₃N₄) powder, 9% of yttria (Y₂O₃), and 11% of aluminum nitride (Aluminum Nitride, AlN) are added to prepare a raw material by a spray dry process (S1). Since the spray drying process is a known process, description thereof will be omitted. The raw material produced here is in the form of powder in the form of granules.

Then, the raw material is filled in a mold and then processed into a press to produce a press-formed product (S2). The molded article manufactured by using a press is manufactured from the raw material in the form of a disk as a spare part in the form of a disk in consideration of the dimensions of the finished product.

Then, the molded product is pre-sintered at 600 ° C to 800 ° C for 15 hours (S3). It is preferable to presinter at about 700 ° C., and to pre-sinter to secure strength for degreasing and forming, and to increase the strength and hardness of the silicon nitride tip.

Then, the pre-sintered molded article is processed into a tip shape (S4). In other words, the disk-shaped spare parts after the pre-sintering is completed are processed into the shape of the tip using an automatic lathe.

Then, the milled tip is sintered at 1,740 ° C. for 2-3 hours at 100-200 atmospheres of argon (Ar) (S5). After the pre-sintering step as described above, and then processed into a tip shape, and then subjected to the argon pressure sintering step, the strength, hardness, brittleness of the silicon nitride tip is improved and the thermal shock resistance is improved.

Then, the tip through the argon pressure sintering step (S5) using a diamond abrasive stone to process the outer diameter, inner diameter, thickness to complete the silicon nitride tip (S6). That is, the 1st hole 17 and the 2nd hole 18 are machined in the tip. Hole and thickness machining using diamond abrasive stone is processed to have an error of ± 0.01mm.

Then, the hot hole oral cavity (skd61) having the heat treatment hardness HRC 48-52 is roughed by 0.1% less than the outer diameter of the silicon nitride tip 20, and the second hole 16 and the outer diameter are roughened. To process the metal case to be inclined upward 2.5 degrees (S7).

Then, the metal case 20 is heated to 400-450 ° C., and then the completed silicon nitride tip 20 is shrinked to the heated metal case 12 (S8).

<Physical Characteristic Test>

The silicon nitride extrusion die thus processed is compared with the zirconia extrusion die of the prior art and the physical properties are shown in Table 1 below.

Physical properties

unit
Silicon Nitride Extrusion Die
Zirconia Extrusion Die
Density

(g / cm3)
3.3
5.7
Hardness

(Hv)
1,700
1,200
Transverse Rupture Strength
(Kgf / mm2)
120
100
Fracture toughness

(Mpa.m½)
6.5
9.0
Compressive Strength
(Mpa)
4,000
1,800
Thermal Shock Resistance
(℃)
800
500

As can be seen in Table 1 above, the characteristics of the silicon nitride produced by the manufacturing method of the present invention has a slightly lower fracture toughness, but the service life is improved due to excellent compressive strength, and excellent thermal shock resistance can lead to early microcracks. There is an effect to prevent, and the hardness is excellent has the advantage of improving the surface roughness of the material to be extruded.

<Application experiment>

Application experiments were performed in which the billet was extruded using the silicon nitride extrusion die of the present invention and the zirconia extrusion die of the prior art. The billet grade was C2700, the extruder used was 2,500 tons press and the billet preheating temperature was 850 ° C.

The experimental results are shown in Table 2 below.

division
Zirconia Extrusion Die
Silicon Nitride Extrusion Die
1st experiment
7 times
Episode 19
2nd experiment
12th
23 times

As shown in Table 2, the zirconia extrusion die of the prior art could not be used after 7 billet extrusions in the first experiment, but only 12 times in two tests. However, in the case of the silicon nitride extrusion die of the present invention, the billet extrusion was possible 19 times at a time and 23 times at a second time.

It will be apparent to those skilled in the art that various modifications and variations may be made in the present invention. Therefore, it is to be understood that the present invention is not limited to the above-described embodiments. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims. It is also to be understood that the invention includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

10. Silicon nitride extrusion die
12 ... metal case
13,14.Outside of metal case
15.The first hole in the metal case
16 ... 2nd hole in metal case
17.The first hole of the silicon nitride tip
18.Second hole of silicon nitride tip

Claims (3)

Metal case; And
And a silicon nitride (Si₃N₄) tip shrink-fitted into the metal case.
The silicon nitride tip is composed of 80% by weight of silicon nitride (Si₃N₄) powder, yttria (Y₂O₃) 9%, aluminum nitride (Aluminum Nitride, AlN) 11%,
The silicon nitride tip,
80% by weight of silicon nitride (Si₃N₄) powder, 9% of Y₂O₃ and 11% of aluminum nitride (Aluminum Nitride, AlN) were added to prepare a raw material by a spray drying process. A silicon nitride extrusion die, wherein a press-formed product is prepared, and the molded product is presintered at 600 ° C. to 800 ° C. for 15 hours, and then pressurized and sintered at 1,740 ° C. for 2 to 3 hours with argon (Ar). delete (a) adding 80 wt% of silicon nitride (Si₃N₄) powder, 9% of Y2O₃, and 11% of aluminum nitride (Aluminum Nitride, AlN) to prepare a raw material by spray drying;
(b) preparing a press-molded product by filling the raw material into a mold and then pressing;
(c) pre-sintering the molded product at 600 ° C. to 800 ° C. for 15 hours;
(d) processing the presintered molded article into a tip shape;
(e) pressure sintering the processed tip at 1,740 ° C. for 2-3 hours at 100-200 atmospheres of argon (Ar);
(f) processing the outer diameter, the inner diameter, and the thickness of the tip that has passed through the step (e) using diamond abrasive stone to complete the silicon nitride tip;
(g) roughing the hot-hole oral cavity (skd61) having a heat treatment hardness of HRC 48-52 to less than 0.1% of the outer diameter of the silicon nitride tip to prepare a metal case;
(h) shrinking the finished silicon nitride tip in a metal case heated to 400 -450 ° C .; a method of manufacturing a silicon nitride extrusion die, comprising: a.

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