JPH0671406A - Injection sleeve for die casting and method for casting aluminum or aluminum alloy member - Google Patents

Abstract

PURPOSE:To obtain an injection sleeve for die casting having excellent erosion resistance and high temp. strength to a molten metal by composing it with a cylindrical cermet sintered body constituted of the hardened phase of Ni-Mo complex boride, etc., and a metallic combined phase mainly dissolving Mo into Ni as a solid solution and containing the specific range of the hardened phase in the sintered body. CONSTITUTION:The injection sleeve 1 for die casting is composed of the cylindrical cermet sintered body 2 constituted of the hardened phase containing one or more kinds of Ni-Mo complex boride, Ni-W complex boride and Ni-Mo-W complex boride and the metallic combined phase mainly dissolving Mo into Ni as the solid solution. Further, the injection sleeve 1 is incorporated into the hardened phase in the cermet sintered body at 50-90wt.%, and fitted with a metallic cylinder 3 on the outer periphery of the cermet sintered body 2. By this constitution, as the cermet sintered body has excellent erosion resistance to the molten metal and high strength at the high temp., even if the cooling to the part in contact with the molten metal is not executed, the service life of the injection sleeve can be prolonged.

Description

Detailed Description of the Invention

[0001]

The present invention relates to aluminum (Al),
The present invention relates to a die casting injection sleeve used for die casting a molten metal such as an Al alloy and zinc (Zn).

[0002]

2. Description of the Related Art Molten metal such as Al, Al alloy, and Zn is supplied to an injection sleeve of a die casting machine, and the molten metal is injected into a die casting mold at high speed by a plunger tip and solidified in the mold by applying high pressure. The die-casting method is widely used for manufacturing metal parts in the industries for manufacturing automobiles, electric devices and the like. The reason is that the time required to cast one product is significantly shorter than other casting methods, and the manufacturing cost is low.

In the die casting method, the casting cycle in which the molten metal is fed into the die of the casting machine at a high flow rate and solidified is completed in a very short time as compared with other casting methods.
Because this casting cycle is repeated in a short cycle, the parts that come into contact with the molten metal, especially the injection sleeve and die casting mold, have excellent corrosion resistance and erosion resistance to the molten metal and thermal shock resistance to repeated heating and cooling cycles. Material is needed.

When casting Al or Al alloy having a relatively high casting temperature, these parts are required to withstand extremely harsh conditions. Conventionally, as the material for these parts, heat treatment is applied to hot die steel. It is used after being subjected to nitriding treatment.

Further, there is a considerable difference in the condition of contact with the molten metal between the injection sleeve and the die casting mold. That is, when the temperature of the molten metal fed into the mold decreases, the viscosity of the molten metal increases, and a part of the molten metal becomes semi-solidified. When the viscosity of the molten metal increases or the solidified phase precipitates, the structure of the cast product becomes inhomogeneous and adversely affects the product properties.Therefore, it is necessary to avoid cooling the molten metal as much as possible in the injection sleeve. Since the mold is a part that solidifies the molten metal inside the mold, it is sufficiently cooled.

The inner surface of the injection sleeve, especially the hot water contact portion near the bottom of the hot water supply port, is in contact with molten metal having a relatively high temperature, so that erosion is severe, and the injection sleeve made of hot die steel is subjected to nitriding treatment. Even if it is used, its service life is short. However, no other conspicuous material has been found as a material for the injection sleeve other than the hot die steel, and the hot die steel injection sleeve is used while cooling the part that is severely corroded within the allowable range of the injection sleeve. Is the current situation.

Further, the plunger tip (a piston-like member, the surface of which is made of Cormorloy alloy and the inside of which is water-cooled) is rapidly moved in the injection sleeve to move the molten metal into the mold for a short time. Since there must be a press fit between them, sufficient lubricity must be maintained between the inner surface of the injection sleeve and the plunger tip. In this respect as well, there is a problem with the injection sleeve of hot die steel, and it is necessary to supply about 10 ml of the lubricant in which carbon and water are mixed each time casting is performed. The lubricant is thermally decomposed into gas by the heat of the molten metal, and this gas is taken into the molten metal to cause pores to remain in the cast product.

In recent years, for the purpose of solving these problems, ceramics having a substantially high corrosion resistance to molten metal and a large thermal shock resistance due to a small coefficient of thermal expansion, for example, Sialon in JP-A-63-72464. To
Japanese Examined Patent Publication No. 60-2949 attempts to use silicon nitride for an injection sleeve for die casting.

However, the toughness and thermal shock resistance of these ceramic sleeves are not sufficiently large, and even if the ceramic sleeve is reinforced by fitting it to a metal cylinder,
The coefficient of thermal expansion (3 to 4 × 10 ⁻⁶ / ° C.) is remarkably 13 to 14 × in the case of SKD-61 or the like.
Since it is less than 10 ⁻⁶ / ° C.), the reinforcing effect in the operating temperature range is hardly obtained, and there are problems that the operating conditions are limited, and that mechanical damage or thermal shock causes damage during use.
It has not reached the stage of practical use.

Soviet Powder Metal
lurgy and MetalCeramics N
o. 8 (44) P665-670, 1966 and Japanese Patent Application Laid-Open No. 62-196353 propose a cermet sintered body having a Mo-Ni-based compound boride as a hard phase and a Ni-based alloy as a binder phase. . Then, it is said that if Cr is further added to the cermet sintered body of this system, the chemical corrosion resistance and the oxidation resistance of the cermet sintered body are improved.

The inventors of the present invention disclosed in Japanese Patent Laid-Open No. 63-143236.
In, a hard phase mainly composed of Ni-Mo-based compound boride, Ni-W-based compound boride or Ni-Mo-W-based compound boride,
We proposed a cermet sintered body composed of a Ni-Mo alloy and a metallic binder phase, and showed that it is a material that has higher strength and hardness at high temperatures than WC-Co cemented carbide. It was Further, JP-A-1-131070 proposes a cermet sintered body of this system to which carbide is added in order to improve strength and hardness at high temperature.

Furthermore, the inventors of the present invention have disclosed in Japanese Patent Laid-Open No. 2-299.
In 740, as a specific application of these cermet sintered bodies, a mold (cooled) for die casting a molten metal such as Al or Zn is proposed.

However, whether the cermet sintered body of this system can be used as an injection sleeve for aluminum used under more severe conditions depends on whether the cermet sintered body is N or less.
Since a metal binder phase containing i as a main component is included, and this metal binder phase is relatively likely to react with molten aluminum or the like and has low corrosion resistance, the adaptability when cooling is not effective was unclear.

[0014]

SUMMARY OF THE INVENTION It is an object of the present invention to find a material which can solve the above-mentioned problems and to provide an injection sleeve for die casting which has excellent durability.

[0015]

The present invention has been made to achieve the above object, and an injection sleeve for die casting according to the present invention comprises a compound of Ni and Mo, a compound of Ni and W, and A hard cermet mainly composed of one or more of Ni, Mo and W compound borides, and a cylindrical cermet sintered body composed of a metal binder phase in which Mo is mainly dissolved in Ni.
Content of hard phase of cermet sintered body is 50 wt% or more 9
It is characterized by being 0% by weight or less.

The injection sleeve according to the present invention includes Mo, W, Ni, MoB, WB, as described in JP-A-63-143236 and JP-A-4-28840.
Ni-B alloy, Ni and Mo compound boride, Ni and W compound boride, Ta, Nb, Cr, Co, TaB ₂ , NbB ₂ ,
Mixing and crushing powder such as WC and TiC as starting materials
The molded and sintered cermet sintered body is further finished into a required size and configuration by grinding with a diamond grindstone, electric discharge machining, press fitting into a metal cylinder, or the like.

Among the components of these cermet sintered bodies,
Ta and Nb have the effect of increasing the strength, toughness and corrosion resistance of the cermet sintered body, Co has the effect of increasing the toughness and high-temperature strength of the cermet sintered body, and carbides such as WC and TiC have the cermet sintered body. Has the effect of increasing the strength and hardness, and Cr has the effect of increasing the oxidation resistance of the cermet sintered body. The preferable addition amount of these components to the raw material is 8 to 15% by weight of Cr and Co, 2 to 8% by weight of Ta, 1 to 5% by weight of Nb, and 0.5 to 15% by weight of carbide.
Is. If the addition amount of these components is small, almost no effect of improving the material properties of the cermet sintered body can be obtained, and if too much is added, an unfavorable phase occurs and the toughness of the cermet sintered body is small. Prone.

The structure of the cermet sintered body of this system is such that the hard phase particles are surrounded by the metal binding phase, and the hard phase composed of complex boride has a polygonal cross section. Has an average particle size of, for example, about 5 μm, and the thickness of the metallic binder phase separating the hard phases is usually 5 μm.
It is the following.

In the die casting injection sleeve of the present invention,
By using the cermet sintered body of a specific material, the service life of the injection sleeve is significantly extended without using cooling, as compared with the case of using the injection sleeve using the conventional hot die steel. Further, by using the injection sleeve for die casting of the present invention, it is possible to obtain a desirable effect which was not expected at first as described later, the durability of the injection sleeve is excellent, and the quality of the product to be die cast is remarkably improved. Be improved.

The hard phase of these complex borides has superior corrosion resistance to molten metals such as Al as compared with the metallic binder phase, while the metallic binder phase has lower corrosion resistance to molten metal. . The reason why the amount of the complex boride contained in the cermet sintered body is 50% by weight or more is that the hard phase of the complex boride is 50% by weight or more because SKD6
This is because it has excellent corrosion resistance as compared with hot die steel such as 1 (JIS standard) and can significantly extend the service life of the injection sleeve. However, if the content of the hard phase composed of a double boride of the cermet sintered body exceeds 90% by weight, the cermet sintered body becomes brittle, and the injection sleeve is cracked by thermal shock when casting aluminum or the like. It tends to occur.

Considering the corrosion resistance of the cermet sintered body which determines the durability of the injection sleeve and the strength at high temperature, the cermet sintered body has a long life as an injection sleeve due to its excellent corrosion resistance to molten metal. The content of the hard phase therein is preferably 65% by weight or more and 80% by weight or less, more preferably 70% by weight or more and 80% by weight or less.

The metal binder phase is a Ni alloy in which Mo or the like is solid-dissolved in Ni, and the hard phase of the complex boride dissolves in the Ni alloy to some extent in the high temperature range where sintering is performed. Has a good wettability between the hard phase and the metal binding phase, and has a large interfacial strength between the hard phase and the metal binding phase when formed into a cermet sintered body.

When Mo is solid-dissolved in the Ni alloy, the cermet sintered body has high corrosion resistance to molten metal. However, if the Mo content is too large, Mo that is not solid-dissolved in the Ni alloy may precipitate as an intermetallic compound and deteriorate the material properties. Therefore, the solid solution amount of Mo in the Ni alloy is 10% by weight or more and 30% by weight or less, and more preferably 15% by weight or more and 25% by weight or less. Strength of the sintered body,
Hardness and corrosion resistance to molten metal are ensured, and an intermetallic compound which causes deterioration of material properties due to interaction of extra metals is not formed during sintering.

The weight% of the hard phase in the cermet sintered body is
It can be obtained by approximate calculation assuming that all B components are incorporated in the complex boride, and from the ratio of the area of the hard phase on the surface of the cermet sintered body, observed by SEM. Can be calculated. The specific gravities of the hard phase and the metallic binder phase change to some extent depending on their chemical compositions, but are generally in volume% ≈ weight%.

Furthermore, when an injection sleeve made of such a cermet sintered body is used for casting molten metal, cermet is formed by carbon particles or Al oxides derived from the lubricant supplied to the injection sleeve in the early stage of its use. In addition to the metal binder phase on the surface of the sintered body being abraded, the metal binder phase is selectively eroded by the molten metal such as aluminum and eroded to a depth of about 1 μm. However, the erosion depth is shallow compared to the size of the hard phase particles, so
The hard phase crystal particles do not drop from the surface of the cermet sintered body.

Thereafter, even if the casting of the molten metal is repeated,
Since the molten metal has a certain degree of viscosity and is difficult to wet with the hard phase on the surface, the erosion of the metal bonded phase in the position receding from the surface is remarkably slow, and it is excellent even without cooling the injection sleeve. Shows durability.

Further, it has been recognized that the sliding resistance between the plunger tip and the plunger tip at the operating temperature does not involve the metal binding phase for the above-mentioned reason, and the sliding resistance of the injection sleeve is remarkably reduced. It is considered that this is because the hard phase of the cermet sintered body is a double boride.

When die casting of Al or Al alloy is performed using a conventional injection sleeve of hot die steel, the heat conductivity of the hot die steel is considerably large and it is partially cooled. , The temperature of the molten metal at the contact surface with the injection sleeve lowers and a part solidifies, causing a so-called fracture chill layer in the cast structure of the cast product, which causes the mechanical properties of the cast product to deteriorate. Was there.

Further, when the temperature of the molten metal decreases, the viscosity of the molten metal inevitably increases and the flow velocity of the molten metal injected into the mold decreases. As a result, the packing density of the molten metal in the corners of the die casting mold becomes smaller, the time required for pouring becomes longer, the cooling rate of the cast molten metal becomes slower, and the metal structure of the cast product becomes coarse. However, the material properties of the cast product were not as good as expected due to the formation of a dendritic crystal structure.

Using the injection sleeve according to the invention,
With respect to these problems, the following remarkable improvement effects can be obtained. That is, the double boride constituting the hard phase of this cermet sintered body is characterized in that it is difficult to wet the molten metal to be cast, and the position where the molten metal recedes from the surface when no pressure is applied to the molten metal. It does not come into contact with the metallic binder phase in. When pressure is not applied to the molten metal, the molten metal does not adhere to the entire surface of the injection sleeve and the heat transfer area is small, which makes it difficult to cool the molten metal introduced into the injection sleeve. To be

The hot die steel (SKD61) has a thermal conductivity of 2 (unit: cal / cm · sec · ° C.).
It is 0.073 at 0 ° C and 0.
068, whereas in the example of the cermet sintered body used in the injection sleeve of the present invention, it is 0.032 each.
Since it is 0.050, it is difficult to cool the molten metal from this point as well.

Thus, the molten metal having a high temperature and a small viscosity is injected into the die casting mold at a high speed, the pressure of the plunger tip reaches the corner of the mold, and the molten metal is filled into the mold without any gap. , Solidification is completed within a short time, and the amount of lubricant used can be reduced, so the crystal structure of the cast product becomes fine and dense, and the conventional injection sleeve is used, such as a broken chill layer and residual pores. By doing so, many problems are solved at the same time, and the properties of the cast product are significantly improved.

The injection sleeve does not have to be the cermet sintered body as a whole, but the injection sleeve can be made cheaper by fitting a metal cylinder to the outer periphery of the cylindrical cermet sintered body by shrink fitting. It can be manufactured, and the practical use strength of the sleeve can be further increased by shrink fitting and applying compressive stress from the outer periphery. In this case, since the difference between the coefficient of thermal expansion of the cermet sintered body (8.5 to 9 × 10 ⁻⁶ / ° C.) and the coefficient of thermal expansion of the metal cylinder is not so large as that of the above-mentioned ceramics, the reinforcing effect by shrink fitting Is sufficiently effective even at the working temperature of the sleeve.

Further, since the hard phase of the double boride has excellent corrosion resistance to the molten metal, when the molten metal having a high erosion, that is, the molten metal having a high temperature is supplied into the injection sleeve,
The durability of the injection sleeve can be further improved by increasing the content of the hard phase in the portion that first contacts the molten metal.

As a specific method for producing such an injection sleeve, for example, when a cylinder is formed by isostatic pressing, a part of the surface of the core die is coated with a raw material powder having a high hard phase content. Then, by filling the rubber mold with the usual raw material powder and molding, a molded body in which the coating layer having many hard phases is integrated on the inner surface side of the cylinder is obtained. Further, by coating the surface of the core mold with the hard phase content varied, a sleeve having a hard phase content can be obtained.

At the portion where the injection sleeve of the cylindrical cermet sintered body comes into contact with the die-casting mold, it is necessary to press the injection sleeve firmly and fix it, so that corner breakage easily occurs. However, this part is eroded slowly because heat is taken away by the contacting mold (which is cooled).
By increasing the content of the metal bonding layer in this portion to increase the toughness, the problem of corner chipping can be avoided.

The injection sleeve of the present invention having such a structure can also be manufactured by the above-mentioned isostatic press, and a separately manufactured ring-shaped cermet sintered body may be diffusion-bonded. As another convenient method, a ring of hot die steel may be arranged at this portion.

In another preferred injection sleeve for die casting of the present invention, a cylindrical cermet sintered body injection sleeve is provided with a taper portion on the outer periphery in the vicinity of the end portion in contact with the die casting mold, and the corresponding end portion of the metal cylinder is provided. It is fitted with a taper part provided on the inner circumference near the part so that the other end of the cylindrical cermet sintered body does not come out by the metal ring attached to the other end of the metal cylinder. It is fixed.

Since the vicinity of the injection sleeve that comes into contact with the die casting mold is shrink-fitted by the tapered portion,
The entire inner surface of the injection sleeve up to the part that comes into contact with the die-casting mold can be made of a cermet sintered body, whereby good durability of the injection sleeve can be ensured. In addition, when heat-fitted with a metal having a larger coefficient of thermal expansion and a smaller Young's modulus than the cermet sintered body,
The cylindrical cermet sintered body may partially project due to the residual stress associated with the shrink fitting.

For this reason, the cylindrical cermet sintered body may come out of the injection sleeve and the cylindrical cermet sintered body may be chipped, but a metal ring is attached to the plunger tip side of the injection sleeve. Since the cylindrical cermet sintered body does not protrude from the metal cylinder because it is fixed by screwing or welding so that it does not come out, there is no risk of chipping. Further, if a compressive stress in the vertical direction is applied to the cermet sintered body having a toughness lower than that of the metal material, the cylindrical cermet sintered body is further reinforced.

With the die casting apparatus incorporating the injection sleeve of the present invention, particularly preferable effects can be obtained when casting Al or Al alloy. That is, when casting Al or an Al alloy, the temperature of the molten metal supplied to the injection sleeve is as high as 650 ° C. to 720 ° C. Therefore, the portion of the injection sleeve below the hot water supply port that first contacts the molten metal melts. Severe erosion and thermal shock from metal.

However, the injection sleeve of the present invention can withstand this severe condition without cooling and exhibits good durability. Thus, the temperature of the molten metal sent to the die casting mold can be maintained at an appropriate temperature, and the molten metal is sent at high speed to every corner of the mold and solidifies in a short time, so the quality of the cast metal member is improved. Noticeably improved.

[0043]

EXAMPLES Specific examples of the injection sleeve according to the present invention will be described below, but the present invention is not limited to the following examples.

Test Example 1 MoB in an amount of 53% by weight, WB in an amount of 7% by weight, Ni in an amount of 33% by weight, and Mo in an amount of 7% by weight were weighed, ethyl alcohol was added to these powders as a dispersion medium, and the mixture was placed in a pot mill. Cylinder cermet sintering with inner diameter 60mm, outer diameter 70mm, length 250mm after being mixed and pulverized in 1), dried under reduced pressure, sintered into a cylindrical shape with an isostatic press, sintered at 1300 ° C, and ground. I made it a body. The cermet sintered body probe produced at the same time as the cermet sintered body using the same raw material had a hard phase content of 72% by weight, a bending strength of 210 kg / mm ² , and a fracture toughness of 17 MN / m ^3/2 . .

A cylinder of hot die steel was shrink-fitted onto the outer periphery of this cylindrical cermet sintered body to obtain an injection sleeve.
A hot water inlet having an inner diameter of about 50 mm was provided on the peripheral surface of the injection sleeve. As shown in the sectional view of FIG. 1, this injection sleeve was assembled to a 250-ton type die casting machine,
Die casting of an Al alloy (ADC12) was performed at a casting interval of 28 seconds. Cast product is 3mm x 30mm x 6
It is a flat plate with a groove of 0 mm.

In this test, the temperature of the molten Al alloy supplied was 680 ° C., and the amount of the molten metal supplied was about 70.
The injection speed was 0 g / time, the injection speed was 2.5 m / min, the amount of the lubricant (water containing carbon) was 0.3 ml / time, and the water cooling at the lower part of the hot water inlet, which was performed by the conventional injection sleeve, was not performed. . The life of this injection sleeve was recorded at about 330,000 times, and the limit of the service life was that the inside of the sleeve immediately below the hot water inlet was dented by erosion and the movement of the plunger tip was not smooth.

In FIG. 1, 1 is an injection sleeve, 2 is a cylindrical cermet sintered body, 3 is a metal cylinder, 4 is a die sleeve of hot die steel, 5 is a plunger chip, 6 is a die casting mold, and 7 is a die die. Is the hot water supply port.

Test Example 2 Using a conventional nitriding hot die steel (SKD61) injection sleeve, die casting was performed under the same conditions as in Example 1. However, in this example, casting was performed while water cooling was applied to the lower part of the hot water supply port.

Density of about 100 die-cast 3 mm × 30 mm × 60 mm grooved flat plates in Test Example 1 and Test Example 2 and bending strength of test pieces cut out from the flat plates (assuming that the cast product does not elastically deform). ) Was measured, and the cumulative distribution of the density of the cast product was compared with the ratio of the test piece remaining without breaking when the bending stress was applied (probability of remaining),
Graphs are shown in FIGS. 2 and 3, respectively. From these graphs, by using the injection sleeve of the present invention,
It can be seen that the properties (density and flexural strength) of the cast product are significantly improved. The injection sleeve of Test Example 2 was unusable because the inside of the injection sleeve was eroded, and its service life was about 120,000 times.

Test Examples 3 to 10 In the same manner as in Test Example 1, an injection sleeve made of a cylindrical cermet sintered body having the composition shown in Table 1 was prepared and a casting test was conducted. Table 1 also shows the content of the hard phase of the cermet sintered body, the bending strength, the fracture toughness, and the service life of the injection sleeve.

Test Example 11 A casting test was carried out using the above-mentioned conventional hot die steel injection sleeve without cooling the portion of the molten metal that hits the beginning of the molten metal. Four
It took as short as 200 times.

The reason why the injection sleeve could not be used continuously was as follows: Test Examples 3, 4, 6, 8, 9, 10 and 11
This is due to erosion directly under the hot water supply port, and in Test Examples 5 and 7, cracks occurred in the injection sleeve when casting was restarted after the casting was temporarily stopped.

FIG. 4 is a sectional view showing another example of the injection sleeve for die casting of the present invention. In the drawing, 8 is a metal ring, 9 is a tapered portion, and 10 is welding. In this example, a part of the cylindrical cermet sintered body does not come out of the metal cylinder due to the shrink fitting with the metal ring and the taper portion, and the trouble such as corner chipping does not occur.

[0054]

[Table 1]

[0055]

In the injection sleeve according to the present invention, the cermet sintered body has a good effect of reinforcement by shrink fitting, and the cermet sintered body has excellent corrosion resistance to molten metal and strength at high temperature, so that cooling of the hot water contact portion is achieved. The life of the injection sleeve can be significantly extended without performing Further, since the sliding resistance between the injection sleeve and the plunger tip is small, it is possible to greatly reduce the amount of the lubricant used, which is a cause of introducing air bubbles into the product.

Further, the cooling rate through the cermet sintered body forming the injection sleeve is lower than that of the conventional hot die steel, and the cooling of the injection sleeve can be omitted, so that the molten metal temperature can be adjusted to an appropriate temperature. It can be held and the molten metal can be pressed all the way to the corners of the die casting mold while maintaining the appropriate temperature in a short time, and the cooling and solidification is completed in a short time.
Thus, these combined effects can significantly improve the properties of the die cast product.

Therefore, when the injection sleeve according to the present invention is used, the service life of the injection sleeve is extended, the operating rate of the die casting apparatus can be increased, and the defects in the cast product are reduced, so that the product yield is improved. At the same time, the product quality is significantly improved. Since die casting is more actively used in the manufacture of metal parts in the future, its industrial utility value is great.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a situation in which a die casting injection sleeve of the present invention is attached to a die casting apparatus.

FIG. 2 is a graph showing a cumulative frequency distribution of densities of cast products obtained by using the die-casting injection sleeve of the present invention and the conventional die-casting injection sleeve.

FIG. 3 is a graph showing the residual probability of bending strength of a cast product obtained by using the die casting injection sleeve of the present invention and the conventional die casting injection sleeve.

FIG. 4 is a sectional view showing another example of the injection sleeve for die casting of the present invention.

[Explanation of symbols]

 1: Injection Sleeve 2: Cylindrical Cermet Sintered Body 3: Metal Cylinder 4: Hot Die Steel Die Sleeve 5: Plunger Chip 6: Die Casting Die 7: Water Heater 8: Metal Ring 9: Tapered Part 10 :welding

Claims (7)

[Claims] 1. A hard phase mainly composed of a complex boride of Ni and Mo, a complex boride of Ni and W and one or more complex boride of Ni, Mo and W, and Mo mainly dissolved in Ni. It is composed of a cylindrical cermet sintered body composed of a metallic binder phase, and the hard phase content of the cermet sintered body is 50% by weight or more and 90% or more.
An injection sleeve for die casting, which is characterized by being less than or equal to weight%. 2. The injection sleeve for die casting according to claim 1, wherein the content of the hard phase of the cermet sintered body is 65% by weight or more and 80% by weight or less. 3. The injection sleeve for die casting according to claim 1, wherein a metal cylinder is fitted around the outer periphery of the cylindrical cermet sintered body. 4. The cylindrical hard cermet sintered body according to claim 1, wherein the content of the hard phase in the lower portion of the hot water inlet which first comes into contact with the molten metal to be cast is Injection sleeve for die casting, which is more than the content of hard phase in the part. 5. A cylindrical cermet sintered body according to claim 1, wherein the content of the hard phase in a portion contacting the mold is higher than that of the hard phase in other portions. Injection sleeves for die casting are being reduced. 6. The metal cylinder according to claim 3, wherein the injection sleeve of the cylindrical cermet sintered body is provided with a taper portion on the outer periphery in the vicinity of the end portion in contact with the die casting die. The other end of the cylindrical cermet sintered body is fitted with the taper part provided on the inner circumference near the end that does not come out due to the metal ring attached to the other end of the metal cylinder. Injection sleeve for die casting that is fixed like. 7. A hard phase mainly containing at least one of a compound boride of Ni and Mo, a compound boride of Ni and W and a compound boride of Ni, Mo and W, and Mo mainly dissolved in Ni. A metal cylinder is fitted to the outer periphery of a cylindrical cermet sintered body composed of a metal binder phase, and the hard phase content of the cermet sintered body is 50% by weight or more and 90% by weight or less. A method for casting an aluminum or aluminum alloy member, which comprises casting with a die casting apparatus incorporating an injection sleeve.