JPH029641B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a high-density sintered body by hot isostatic pressing (hereinafter referred to as HIP).

[Prior Art] Fe-based or Co-based magnetic materials containing rare earth metals such as TbFe, GdTbFe, TbFeCo, and GdDyFeCo are used as recording media for magneto-optical disks. This recording medium is formed as a thin film on an acrylic or epoxy substrate by sputtering. This type of thin film recording medium is required to have uniformity of components, as well as high purity and low oxygen content. Therefore, it is strongly required that the sputter target substrate be made of a material with high density, high purity, and low oxygen content.

Conventionally, casting methods and methods of hot-pressing pulverized powder have been known as methods for manufacturing sputter target substrates, but these methods have a fatal flaw in that dense products cannot be obtained.

As a way to overcome this fatal flaw,
Although the HIP method using a container is known, the HIP method cannot simply be applied to Fe-based or Co-based alloys containing rare earth metals because they have a large oxygen affinity.

For this reason, the applicant has already filed the patent application No. 60-190930.
When obtaining a high-density sintered body of Fe-based or Co-based alloy containing rare earth metals by the HIP method, alloy powder 12 is placed in a container 11 and sealed as shown in Figure 1 [ ]. First, the adsorbed gas, moisture, oil, etc. are removed by vacuum heating at a temperature of 850 to 1050°C at a vacuum degree of 10 ^-6 torr or higher, and then the container 11 is sealed and subjected to HIP treatment. proposed a method to do so.

[Problem that the invention seeks to solve]

However, in that method, after the HIP treatment, as shown in Figure 1 [], the sealed container 11
Since it is not compressed uniformly, only the area surrounded by the chain line can be used as a product, and therefore the yield is quite low. Furthermore, since rare earth metals are quite expensive, it is inevitable that the material cost will account for a high proportion of the product price, and therefore it is essential to manufacture the product efficiently.

Therefore, in view of the above-mentioned problems, an object of the present invention is to provide a method for easily and efficiently producing a high-density sintered body of an Fe-based or Co-based alloy containing rare earth metals using the HIP method. It is in.

[Means for solving problems]

According to the present invention, a metal container having a predetermined shape is filled with metal powder to be treated, the container is degassed and sealed, and then the container is subjected to a hot isostatic press treatment at high temperature and high pressure. In the method, a press molded body of refractory powder having a relative density almost matching the relative density of the object to be treated is used as a spacer only above and below the metal powder to form a sandwich-like structure. A hydrostatic press molding method is obtained.

〔Example〕

Similar to the conventional method, a sealed container is used to perform HIP treatment on a high-density sintered body of Fe-based or Co-based alloy containing rare earth metals. , lower surface polishing, grinding,
Fe containing rare earth metals that had been removed by cutting etc.
or Co-based alloy part is replaced with a refractory ceramic press molded body. According to this, an efficient method for manufacturing a sputter target can be provided.

That is, by using a fire-resistant ceramic press molded body as a spacer in the wasteful parts at the top and bottom of Figure 1 [], steps such as polishing, grinding, and cutting can be omitted as much as possible, and Fe-based or It has become possible to manufacture products with good yield without using Co-based alloy powder.

Here, as the refractory ceramic, ceramic powder having poor reactivity with metals such as aluminum oxide, magnesium oxide, boron nitride, and aluminum nitride is used. The press body is generally formed using a conventional mold press or rubber press.

The important thing is to make the relative powder packing density D ₁ of the metal powder after HIP treatment almost equal to the relative powder density D ₂ of the press molded body with respect to the density of the refractory ceramic press molded body after HIP treatment. That's true. (0.9≦D ₂ /D ₁ ≦1.1 is preferable.) When 0.9≦D ₂ /D ₁ , the product yield is poor as in the conventional method, and when D ₂ /D ₁ ≦1.1, the shrinkage rate is low. There are cracks that appear to be caused by differences in the

Below, specific examples of the present invention will be described.

Referring to Figure 2 [], 30 meshes were crushed between two spacers 13 placed inside a stainless steel container 11 with a diameter of 200 mm.
Gd _0.5 Tb _0.5 Fe _2.5 alloy powder 12 is filled with D ₁ = 70%, a lid with an exhaust pipe is welded to the container 11, the exhaust pipe is connected to a vacuum pump, and the inside of the container 11 is heated to 5×10 ^-6 Torr. I degassed until Here, as the spacer 12, a 15 mm thick boron nitride press molded body produced by a rubber press method with D ₂ =68% was used.

Next, the temperature was raised to 1000°C, maintained at 1000°C for 2 hours, and heated and vacuumed. After holding, a part of the exhaust pipe was heat-pressed while continuing vacuum degassing, and then the exhaust pipe was cut to produce a sealed container.

Furthermore, this container is placed in a HIP furnace and the temperature is
HIP treatment was performed under the conditions of 1000°C, 1000 atm pressure, and 2 hours of holding time.

After going through this process, the container
A sputter target substrate was fabricated by taking out a GdTbFe alloy and removing only the surrounding area of the alloy using a lathe along the broken line in Figure 2 [ ], and simply polishing the top and bottom surfaces without cutting them. Furthermore, the structure of the GdTbFe alloy was free of defects such as voids and cracks, and was a high-density material with a relative density of 99.5%. Also, where the oxygen content was measured
The oxygen content was 950 ppm, which was equivalent to the oxygen content in the pulverized powder, which was 970 ppm.
When this material was polished to a mirror finish, brazed to a conductive metal, a sputter target substrate was prepared, and a sputter film was formed, a good magneto-optical recording medium film was obtained.

〔Effect of the invention〕

As described above, according to the present invention, a high-density sintered body with a good yield can be obtained efficiently.

[Brief explanation of drawings]

FIG. 1 shows the conventional hot isostatic press molding method, with [ ] being before HIP treatment and [ ] being after HIP treatment. FIG. 2 is a diagram for explaining an embodiment of the hot isostatic press molding method of the present invention, where [] is before HIP treatment and [] is after HIP treatment. 11... Container, 12... Metal powder, 13... Spacer.

Claims (1)

[Claims] 1. A metal container having a predetermined shape is filled with metal powder to be treated, the container is degassed and sealed, and then the container is subjected to hot isostatic pressing at high temperature and pressure. The heating method is characterized in that a press-molded body of refractory powder with a relative density almost matching the relative density of the object to be treated is used as a spacer only above and below the metal powder to form a sandwich-like structure. Isostatic press molding method. 2. The hot isostatic press forming method according to claim 1, wherein the metal powder is Fe-based or Co-based metal powder containing a rare earth metal. 3. The hot isostatic press molding method according to claim 1 or 2, wherein the refractory powder is a refractory ceramic powder such as aluminum oxide, magnesium oxide, boron nitride, aluminum nitride, or the like.