JPH0732445A - Mgo part stabilized zro2 sintered body die or nipple - Google Patents

Abstract

PURPOSE:To contrive maintenance and an improvement in a product quality by improving mechanical strength, tenacity, welding resistance, frictional resistance and thermal stability and extending life of a die, by a method wherein almina and silica are compounded with a ZrO component which is compounded witch a specific quantity of an alkaline earth metal and lanthanum oxide and stabilized a Mg part. CONSTITUTION:5-10mol% MgO and less than 5mol% of at least one kind or two kinds out of CaO, SrO, Sc2O3, Y2O3 and a lanthanum Oxide are contained as chemical composition. Then a ZrO2 sintered body die or nipple whose MgO part is stabilized contains less than 5 pts.wt. Al2O3 and less than 2 pts.wt. Si02 on the basis of 100 pts.wt. ZrO2 component wherein a residual part is comprised substantially of the ZrO2 and MgO part is stabilized. Hereupon, a die is a nonferrous metal extrusion die of an allay copper and the die or a nipple is an extrusion die or nipple of a polymeric material such as resin or rubber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is mainly applied to magnesia (M
The present invention relates to a die or nipple made of a MgO partially stabilized zirconia (ZrO ₂ ) sintered body using gO) as a stabilizer.

[0002]

2. Description of the Related Art As extrusion dies for non-ferrous metals, metal such as tool steel and cemented carbide has been conventionally used for most of them. However, these metal dies easily cause welding with non-ferrous metals, so-called "dust" having Zn as a main component adheres to the product surface, and the product surface after extrusion is rough due to wear or damage of the die,
There was a problem that the product dimensions changed. Also,
Due to wear and damage of the dies, the dies must be frequently repaired, which also has a drawback of shortening the life of the dies.

On the other hand, as an extrusion die or nipple material for a polymeric material such as resin, most of them have conventionally been made of metal such as carbon steel, tool steel and cemented carbide. However, these metal extrusion dies and the like are likely to cause welding with a polymer material, and so-called "meyer" adheres to the surface of the product, so it is necessary to remove the "meyer" on a regular basis. Further, in recent years, a polymer material added with an inorganic filler may be used for high performance, but when a polymer material added with an inorganic filler is extruded, the product surface after extrusion due to abrasion of a die or the like There were also problems such as rough surfaces and shortened life of dies.

Recently, a partially stabilized ZrO ₂ sintered body has attracted attention as a material for dies (Annu. Conf. Austra).
las Inst. Met.vol.30, P6B-4 (1977), Ceramic Bullu
etinvol.59, P211 (1980), J. Aust. Ceramic Soc. vo
l.13 No.1 P8 (1977)).

For example, in Japanese Patent Laid-Open Nos. 58-161973 and 60-215570, Y ₂ O ₃ or CaO partially stabilized ZrO ₂ sintered bodies, Y ₂ O ₃ which focus on mechanical strength are disclosed. A die using a partially stabilized ZrO ₂ -Al ₂ O ₃ sintered body is described, and JP-A-61-484 is also disclosed.
Japanese Patent Publication No. 83 describes a die using a CeO ₂ stabilized ZrO ₂ sintered body, which is focused on mechanical strength, toughness and thermal durability.

[0006]

In the actual operation of a die for extruding a non-ferrous metal, a lubricant is sprayed to reduce the frictional resistance between the die and the extruded material and improve the surface roughness of the extruded product. Therefore, not only the mechanical strength, toughness, wear resistance, thermal durability and thermal shock resistance of the extruded material are required for the non-ferrous metal extrusion die, but conventionally, these required characteristics are required. There is no proposal to satisfy all of the above.

Japanese Unexamined Patent Publication No. 56-145610 describes an example in which a die made of zirconia ceramics is used in a method for producing a crosslinked polyethylene insulated power cable. However, it is difficult to weld zirconia to a polymer material. Not paying attention.

Further, in a die or nipple for processing a polymer material, not only is it not welded to the extruded material and the surface quality of the extruded product is secured, but also the die or nipple material when kept at 100 to 300 ° C. for a long period of time. The stability of the characteristics is required, but Y mainly containing Y ₂ O ₃ as a stabilizer is used.
_{In the case of the 2} O ₃ partially stabilized ZrO ₂ sintered body, especially 200 to 3
There is a problem of low temperature deterioration when kept at 00 ° C for a long time.

The present invention solves the above-mentioned problems of the prior art, and provides mechanical strength, heat durability, resistance to welding with an extruded material, friction resistance,
An object is to provide a die or nipple made of a MgO partially stabilized ZrO ₂ sintered body, which is excellent in various properties such as thermal shock resistance and thermal stability.

[0010]

A die or nipple made of a partially stabilized ZrO ₂ sintered body of MgO according to claim 1 has a chemical composition of 5 to 10 mol% of MgO, CaO, SrO and Sc.
₂ O _3, Y ₂ O ₃ and one selected from the group consisting of lanthanum oxide or two or more contains less than 5 mol%, MgO partially stabilized ZrO ₂ which the balance of substantially ZrO ₂
It is characterized by containing less than 5 parts by weight of Al ₂ O ₃ and less than 2 parts by weight of SiO ₂ with respect to 100 parts by weight of the component.

The MgO partially stabilized ZrO ₂ sintered die according to claim ₂ is the die according to claim 1, which is a non-ferrous metal extrusion die such as a copper alloy.

The die or nipple made of the MgO partially stabilized ZrO ₂ sintered body according to claim 3 is the resin according to claim 1,
It is characterized by being an extrusion die or a nipple of a polymer material such as rubber.

That is, the present inventor is excellent in mechanical strength, heat durability, resistance to welding with an extruded material, and low friction, and
A MgO partially stabilized ZrO ₂ sintered body having excellent thermal shock resistance and thermal stability was found, and it was found that this sintered body is a very useful material as a die or a nipple, and the present invention was completed. It was

The die or nipple targeted by the present invention is not particularly limited, but for example, mainly brass having an operating temperature of about 600 to 900 ° C.,
Extrusion die used for processing pure copper and other copper alloys. An electric wire coating die, an electric wire coating nipple, an inflation die, a T die, a pipe extrusion die, and a pellet extrusion die used for processing a polymer material having an operating temperature of about 100 to 300 ° C. Is like.

The present invention will be described in detail below.

First, the MgO partially stabilized Zr according to the present invention.
The effect of adding each component to the O ₂ sintered body will be described.

In the following, "mol%" means MgO.
, CaO, SrO, Sc ₂ O ₃ , Y ₂ O ₃ and a lanthanum oxide (hereinafter referred to as “second stabilizer”) and Z.
shows the mole percentage of the internal ratio to the total with rO ₂ ,
"Wt%" indicates the percentage by weight of the total relative to this total.

From the viewpoint of thermal shock resistance of the obtained MgO partially stabilized ZrO ₂ sintered body, the amount of MgO added is 5 to 10 mol%, preferably 5 to 8.5 mol%. If the content of MgO is less than 5 mol%, the sintered body is likely to be cracked due to the phase transition from tetragonal to monoclinic during cooling after firing. If the content of MgO is more than 10 mol%, the amount of monoclinic phase precipitated during this cooling decreases, and the thermal shock resistance deteriorates.

From the viewpoint of the strength of the MgO partially stabilized ZrO ₂ sintered body, the addition amount of MgO is preferably 7 to 10 mol%, particularly 7.5 to 9.5 mol%. When MgO is less than 7 mol%, the obtained MgO partially stabilized ZrO ₂
The amount of the tetragonal phase in the sintered body is small, and the effect of improving the strength due to the tetragonal → monoclinic phase transition is small. MgO is 10 mol%
If it is more, the cubic phase will be stable and the amount of the tetragonal phase will be small, and the strength improving effect due to the phase transition from tetragonal to monoclinic will be small.

In the present invention, the high-performance MgO partially stabilized ZrO ₂ sintered body is obtained by the synergistic effect of the combined use of MgO and the second stabilizer. The obtained MgO partially stabilized ZrO ₂ is obtained. From the viewpoint of thermal shock resistance and strength of the sintered body, the total amount of the second stabilizer is less than 5 mol%, particularly 0.3.
It is preferable to be set to ˜3.0 mol%. When the total amount of the second stabilizer is less than 0.3 mol%, it cannot sufficiently contribute to the improvement of thermal shock resistance and strength, and when it is more than 3.0 mol%, the monoclinic phase that precipitates upon cooling after firing is used. And the thermal shock resistance deteriorates, and at the same time, the cubic phase becomes stable, so that the amount of tetragonal phase is small and the strength improving effect due to the phase transition from tetragonal to monoclinic becomes small.

Among the second stabilizers, examples of the lanthanum-based oxide include La ₂ O ₃ , CeO ₂ , Yb ₂ O _{3 and the} like.

The addition of SiO ₂ and Al ₂ O ₃ is effective in further improving the thermal shock resistance and strength of the obtained MgO-stabilized ZrO ₂ sintered body. The addition amount of these is Mg
Mg partially stabilized ZrO containing O and a second stabilizer
_With respect to the _two components, SiO ₂ is less than 2% by weight, preferably 0.05 to 1% by weight, and Al ₂ O ₃ is less than 5% by weight, preferably 0.05 to ₂ % by weight. SiO ₂ addition is 2
If the amount is over 5% by weight, and the amount of Al ₂ O ₃ added is 5% by weight
In the above cases, the sinterability is impaired and the strength of the obtained MgO-stabilized ZrO ₂ sintered body is reduced.

The monoclinic crystal amount of the MgO partially stabilized ZrO ₂ sintered body of the present invention is preferably 50% by weight or more. The amount of monoclinic crystal is obtained by the following X-ray diffraction method.

[0024]

[Equation 1]

In the MgO partially stabilized ZrO ₂ sintered body, the amount of phase transition from tetragonal to monoclinic can be controlled by controlling the cooling process during firing. Since the phase transition from the tetragonal system to the monoclinic system is accompanied by volume expansion, microcracks are generated around the phase transition region, and it is considered that the presence thereof is one of the factors that improve the thermal shock resistance.

The MgO partially stabilized ZrO ₂ sintered body according to the present invention is prepared by mixing, calcining, and crushing the respective raw materials so as to have a predetermined composition, molding into a predetermined shape, and processing 170
Cubic single-phase region of 0 ° C. or higher, preferably 1700 to 17
It can be obtained by firing at 50 ° C. The sintered body is further ground to have a predetermined shape, size, and surface roughness,
After performing finishing such as polishing, for the die,
Shrink the ceramic die chip into a metal case,
In some cases, they are fixed by caulking to form a die. For the nipple, fix the ceramic nipple tip to the metal shaft by gluing or chilling. The fixing method by shrink fitting does not only work to fix the sintered body (ceramics die) to the metal case by heat, but also by applying a compression preload by shrink fitting to the die chip, It also has the effect of improving the durability.

[0027]

In the present invention, by utilizing the welding resistance and the low friction coefficient between the non-ferrous metal or polymer material which is the extruded material and the ZrO ₂ sintered body, the above-mentioned "dust" and "meyer" are utilized.
Can be prevented from adhering to the product, and a product with good surface properties can be obtained as a product after extrusion.
Also, "dust" and "meyani" attached to the die during use.
The work to dispose of is greatly reduced.

Further, the MgO partially stabilized Zr according to the present invention
Due to the excellent mechanical and thermal characteristics of the O ₂ sintered body, the life as a die or a nipple is significantly extended, and a good action and effect can be obtained for ensuring the quality stability of the product for a long period of time.

That is, since MgO is mainly used as a stabilizer in the present invention, it is possible to prevent the non-ferrous metal from being extruded.
Even if it is kept at a temperature of about 00 to 900 ° C. or a temperature of about 100 to 300 ° C. when processing a polymer material for a long time,
No deterioration in strength due to the phase transition from tetragonal to monoclinic at 200 to 300 ° C., which is a problem with Y ₂ O ₃ partially stabilized ZrO ₂ sintered bodies, is observed. In addition to MgO, CaO,
By containing less than 5 mol% of one or two or more selected from the group consisting of SrO, Sc ₂ O ₃ , Y ₂ O ₃ and lanthanum oxide, it is possible to further improve the mechanical strength. .

In addition to MgO, CaO, SrO, Sc
₂ O _3, Y ₂ O ₃ and one selected from the group consisting of lanthanum oxide or two or more contains less than 5 mol%, MgO partially stabilized ZrO ₂ which the balance of substantially ZrO ₂
Less than 5 parts by weight of Al ₂ O ₃ with respect to 100 parts by weight of the component,
By containing less than 2 parts by weight of SiO ₂ , a sintered body having excellent thermal shock resistance can be obtained without losing mechanical strength, which is particularly effective as a die for extrusion of non-ferrous metal.

[0031]

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless it exceeds the gist.

Examples 1 to 3, Comparative Examples 1 to 4 Y ₂ O ₃ which forms MgO and a second stabilizer as a stabilizer in a high-purity ZrO ₂ raw material having an average particle size of 1 μm or less.
And / or SrCO ₃ , and further each powder of SiO ₂ and Al ₂ O ₃ is added so that the chemical composition after firing becomes the ratio shown in Table 1, mixed, calcined and crushed, and the obtained powder is After forming into a predetermined die shape and processing, the product was baked at 1740 ° C. for 5 hours. In addition, about the comparative example 3, it baked at 1550 degreeC for 2 hours. Table 1 shows various properties of the obtained sintered body. Also,
This sintered body was finished into a one-hole copper extrusion die chip having an outer diameter of 40 mm, an inner diameter of 13.8 mm and a thickness of 10 mm. Then, as shown in FIG. 1 (cross-sectional view), the die chip 1 is shrink-fitted into an inner case 2B of a metal case 2 made of hot work tool steel SKD61, and a life test is performed under the conditions shown in Table 2 as a die for copper extrusion. The results are shown in Table 2. 2A is an outer case.

For comparison, a die made of cemented carbide V3 was examined for various characteristics and similarly processed,
The lifespans were compared and the results are shown in Table 2.

[0034]

[Table 1]

[0035]

[Table 2]

From Tables 1 and 2, the following is clear. That is, according to the die made of the MgO partially stabilized ZrO ₂ sintered body according to the present invention (Examples 1, 2, 3), the conventional ZrO ₂ based material (Comparative Examples 1, 2, 3) and cemented carbide ( Compared with Comparative Example 4), it has become possible to improve the quality of the product and extend the life of the die.

A die made of ZrO ₂ material (Example 1,
2, 3, and Comparative Examples 1, 2, 3), compared to the conventional cemented carbide die (Comparative Example 4), "dust" to the die.
There was very little adherence, and maintenance work was greatly reduced to about 1/10. Furthermore, in Examples 1 to 3, Comparative Examples 1 to 4
The surface quality of the product was better than that of, and the dimensions of the product were stable for a long time.

Examples 4 to 6 and Comparative Examples 5 to 7 The chemical composition after firing was added in the proportions shown in Table 3, and mixed, calcined and crushed in the same manner as in Example 1 to obtain. The powder was molded into a predetermined die shape, processed, and then fired at the temperature and time shown in Table 3. Table 3 shows various properties of the obtained sintered body. In addition, the sintered body was made to have an outer diameter of 25 mm and an inner diameter of 7.5.
A die chip for electric wire coating having a thickness of 10 mm and a thickness of 10 mm was finished. Then, as shown in FIG.
Is shrink-fitted in a metal case 4 made of SUS304, a life test is performed under the conditions shown in Table 4, and the continuous operation time until cleaning the eyelids when used as a wire coating die and the integration until it becomes unusable The times were compared and the results are shown in Table 4.

For comparison, a die made of high-speed tool steel SKH55 was examined for various characteristics and processed in the same manner to compare the lives, and the results are shown in Table 4.

[0040]

[Table 3]

[0041]

[Table 4]

The following is clear from Tables 3 and 4. In the case of the MgO partially stabilized ZrO ₂ sintered die according to the present invention (Examples 4, 5 and 6), the conventional wire coating resin is either vinyl chloride (PVC) or expanded polyethylene (PE). Compared with high speed tool steel (Comparative Example 7),
The continuous operation time that can be operated without removing "dust" is significantly lengthened (20 to 30 times), and the time until the life is reached due to wear of the die, especially at the outlet, is 5 to 6 times.
It has become significantly longer.

In comparison with Examples 4 to 6 and Comparative Examples 5 and 6 of ZrO ₂ type material, the continuous operation time is about 15 to 20 times higher than that of the high speed tool steel (Comparative Example 7) in Comparative Examples 5 and 6. However, regarding the die life, the materials of Comparative Examples 5 and 6 are poor in thermal stability and the characteristics are deteriorated. Compared with this, it is significantly shorter than 1/10.

[0044]

According to the die or nipple made of the MgO partially stabilized ZrO ₂ sintered body of the present invention described in detail above, a non-ferrous metal extruding die such as a copper alloy and an extruding die of a polymer material such as resin or rubber are provided. Alternatively, in the nipple, various properties such as mechanical strength, toughness, resistance to welding with extruded material, friction resistance, thermal shock resistance, thermal stability, etc. are remarkably improved, and the life of the die or nipple is significantly extended. The work required for maintenance is greatly simplified, and product quality can be maintained for a long period of time.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a copper extrusion die produced in an example.

FIG. 2 is a cross-sectional view showing a wire coating die manufactured in an example.

[Explanation of symbols]

 1 dice chip 2 case 3 dice chip 4 case

Claims (3)

[Claims] 1. The chemical composition of MgO is 5 to 10 mol%, and one or more selected from the group consisting of CaO, SrO, Sc ₂ O ₃ , Y ₂ O ₃ and lanthanum oxide is 5 mol%. Less than 100 parts by weight of the MgO partially stabilized ZrO ₂ component whose content is substantially ZrO _2.
A die or nipple made of a MgO partially stabilized ZrO ₂ sintered body, containing less than 5 parts by weight of 1 ₂ O ₃ and less than 2 parts by weight of SiO ₂ . 2. A die made of a MgO partially stabilized ZrO ₂ sintered body, wherein the die according to claim 1 is a non-ferrous metal extrusion die such as a copper alloy. 3. The MgO partially stabilized ZrO ₂ characterized in that the die or nipple according to claim 1 is an extrusion die or nipple of a polymer material such as resin or rubber.
Sintered die or nipple.