JPH10147833A - Manufacture of sintered compact - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacture of a sintered compact having a low coefficient of thermal expansion and excellent in mechanical properties. SOLUTION: A metal powder, containing C, is added to a powdered raw material consisting of, by weight, 33-40% Ni and the balance essentially Fe and containing >=0.1% oxygen as an inevitable impurity. The resultant powder mixture is compacted and then sintered in a nonoxidizing atmosphere, by which a sintered compact, containing <=0.1wt.% C and 0.2wt.% or <=0.3wt.% oxygen and having >=92% relative density, is obtained. By this method, excellent various sintered compact products, having >=92% relative density and low coefficient of thermal expansion, can be manufactured extremely easily, and remarkable effects can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing amber, superamber, and a Kovar sintered body.

[0002]

2. Description of the Related Art When Ni is added to Fe to form an alloy,
It was recognized that as the amount of Ni added was increased, the coefficient of thermal expansion of the resulting alloy was changed.
When the weight becomes 5% by weight, the coefficient of thermal expansion is about 1/10 of Fe.
To show the degree. Thus, this alloy has a very low coefficient of thermal expansion near the practical temperature, and therefore, the "I
"Nvarable" is called an invar alloy, an invar alloy or an invariable steel. The general composition of this invar alloy contains 33 to 40% by weight of Ni,
The balance is made of Fe, and the raw materials prepared for the respective alloy compositions are melted and then machined based on the raw material obtained by plastic working to manufacture parts.

[0003] When Co is further added to the above alloy, the coefficient of thermal expansion of the alloy becomes smaller, and this alloy is called a super invar alloy. As a general composition of such a superamber alloy, Ni is 30 to 33% by weight, Co is 5 to 7% by weight, and the balance is Fe. After melting the raw materials prepared for each alloy composition, Parts are manufactured by machining based on the raw material obtained by processing.

Further, Kovar alloy is known as having a thermal expansion coefficient comparable to that of hard glass or ceramic,
It is used as a sealing alloy for hard glass and ceramic. As a typical composition, 29% by weight of Ni and C
It is known that o is 17% by weight and the balance is Fe and unavoidable impurities (ASTM F15).

[0005] As with the amber alloy and the superamber alloy, the Kovar alloy is mainly produced by a melting method.

[0006]

However, in general, a lot of unnecessary parts are generated at the time of molding, and when parts are formed using expensive materials, the final price of the products is expensive. Is causing it.

On the other hand, when the powder metallurgy method is employed in which a product is formed by sintering a powder and then sintering the product, the ratio of the material used as a product is much higher, and the cost can be significantly reduced. It is possible. However, in the case of simply adopting ordinary powder metallurgy in producing the alloy,
The diffusion reaction between the particles of Ni powder, Ni powder and Co powder is difficult to progress, and as a result, it is difficult to obtain a sufficient density as a product. Has to be made much longer, and expensive HIP processing (hot isostatic pressing) or the like must be employed.

Therefore, the present invention has a low coefficient of thermal expansion,
It is an object of the present invention to provide a method for producing a sintered body having excellent mechanical properties.

[0009]

Means for Solving the Problems The present inventor has conducted extensive research to solve the above-mentioned problems and achieve the above-mentioned object.
The present invention has been found to be able to attain the object by molding and processing a raw material powder having a specific composition to which a metal powder containing is added, and then containing a specific amount of C and oxygen and sintering to a specific relative density. Was completed. That is, in the first embodiment of the present invention, the raw material powder containing 33 to 40% by weight of Ni and substantially the balance of Fe and containing 0.1% by weight or more of oxygen as an unavoidable impurity is added to a metal powder containing C. After adding the powder and shaping the resulting mixed powder, sintering is performed in a non-oxidizing atmosphere, containing 0.1% by weight or less of C, 0.2% by weight or less of oxygen, and a relative density of 92%. It is characterized by a method for producing an amber sintered body to obtain the above sintered body,
Further, the second embodiment contains 33 to 40% by weight of Ni,
A metal powder containing C is added to a raw material powder containing 0.1% by weight or more of oxygen as an unavoidable impurity, and a binder is added to the obtained mixed powder to prepare a kneaded product. Further, after the kneaded material is injection-molded, it is sintered in a non-oxidizing atmosphere, containing 0.1% by weight or less of C, 0.2% by weight or less of oxygen, and having a relative density of 92% or more. The present invention is characterized by a method for producing an invar sintered body for obtaining a body.

In a third embodiment of the present invention, Ni is 3
A metal powder containing C is added to a raw material powder containing 3 to 40% by weight, 5 to 7% by weight of Co, the balance being substantially Fe, and containing 0.1% by weight or more of oxygen as an unavoidable impurity,
After molding the obtained mixed powder, it is sintered in a non-oxidizing atmosphere, and contains 0.1% by weight or less of C, 0.2% by weight or less of oxygen, and a relative density of 92% or more. Characterized by the method of manufacturing a super amber sintered body to obtain
Further, the fourth embodiment is characterized in that 33 to 40% by weight of Ni, C
o in an amount of 5 to 7% by weight, with the balance substantially consisting of Fe;
A metal powder containing C was added to a raw material powder containing 0.1% by weight or more of oxygen as an inevitable impurity, a binder was added to the obtained mixed powder to prepare a kneaded product, and the kneaded product was injection-molded. Then, sintering is performed in a non-oxidizing atmosphere to obtain a superamber sintered body containing 0.1% by weight or less of C and 0.2% by weight or less of oxygen and having a relative density of 92% or more. It is characterized by a manufacturing method.

Further, a fifth embodiment of the present invention comprises 28 to 32% by weight of Ni and 15 to 18% by weight of Co, with the balance substantially consisting of Fe and oxygen as an inevitable impurity.
A metal powder containing C is added to a raw material powder containing 1% by weight or more, and the obtained mixed powder is molded and then sintered in a non-oxidizing atmosphere. 0.3% by weight
The sixth embodiment is characterized by a method for producing a Kovar sintered body that obtains a sintered body having a relative density of 92% or more, and a Ni content of 28 to 32% by weight and a Co content of 1%.
A metal powder containing C is added to a raw material powder containing 5 to 18% by weight, the balance being substantially Fe, and containing 0.1% by weight or more of oxygen as an unavoidable impurity, and a binder added to the obtained mixed powder. To prepare a kneaded product, and after injection-molding the kneaded product, sintering was performed in a non-oxidizing atmosphere to reduce C to 0.1.
The present invention is characterized by a method for producing a Kovar sintered body containing 1% by weight or less, oxygen of 0.3% by weight or less, and a sintered body having a relative density of 92% or more.

In the present invention, the non-oxidizing atmosphere is preferably a vacuum atmosphere or a hydrogen atmosphere, and the raw material powder preferably contains 0.6% by weight or less of oxygen. Further, the metal powder to be added to the raw material powder is Fe-C, and the added amount is 5 to 50% by weight.
It is preferable that the particle size is 3 to 20 μm.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In the method for producing an invar sintered body according to the present invention, Ni is contained in an amount of 33 to 40% by weight, and the balance is substantially made of Fe. In particular, it is necessary to add a metal powder containing C to the raw material powder whose upper limit is preferably slightly more than 0.6% by weight. It is necessary to add a metal powder containing C to a raw material powder containing up to 33% by weight, 5 to 7% by weight of Co, the balance being substantially Fe, and containing 0.1% by weight or more of oxygen as an unavoidable impurity. In a method for producing a Kovar sintered body, Ni is contained in an amount of 28 to 32% by weight and Co in an amount of 15 to 18% by weight,
It is necessary to add a metal powder containing C to a raw material powder substantially consisting of Fe and containing 0.1% by weight or more of oxygen as an unavoidable impurity.

Therefore, in any of the above-mentioned methods for producing a sintered body, it is important to add the C component by adding the metal powder containing C after mixing the raw material powder with the desired alloy composition. . By adding the metal powder containing C, when sintering in a non-oxidizing atmosphere in a later step, C reacts with oxygen in the raw material powder to generate and release CO gas. Oxygen in the compact is removed, sintering is promoted, and densification (relative density of 92% or more) of the invar, superinvar, and kovar sintered bodies is achieved.

As a C source to be added, there is a method of adding C powder. However, it is difficult to uniformly disperse the C powder.
O gas generation reaction is suppressed. Therefore, in order to accelerate the reaction of generating CO gas,
It was necessary to extend the holding time. Therefore, by adding a metal powder containing C, for example, Fe-C powder, the metal powder is uniformly dispersed and the reaction of generating CO gas is promoted.

The composition of the raw material powder to which the metal powder containing C is added depends on whether the target sintered body is an amber sintered body, a superamber sintered body or a Kovar sintered body.
Alternatively, the contents of Ni and Co should be within the above-mentioned composition range. However, if these contents are out of the above-mentioned composition range, the thermal expansion coefficient of the produced amber or super-amber sintered body is such that it does not expand practically. The Kovar sintered body does not have the same thermal expansion coefficient as hard glass or ceramic. Further, the content of oxygen contained as an unavoidable impurity in the raw material powder to which the metal powder containing C is added needs to be within the above range.
If the oxygen content is less than 0.1% by weight, the effect of densifying the sintered body by the metal powder containing C cannot be sufficiently exhibited. Further, the upper limit amount of oxygen contained as an unavoidable impurity in the raw material powder to which the metal powder containing C is added,
Usually 0.6% by weight, but may slightly exceed 0.6% by weight. However, if the oxygen content is too large, the amount of C-containing metal powder to be added becomes too large, and it becomes difficult to control the C content of the manufactured sintered body,
The C content of the product after sintering tends to exceed 0.1% by weight.

The average particle diameter of the raw material powder to which the metal powder containing C is added is preferably 3 to 50 μm. It is difficult to obtain a metal powder having an oxygen content of about 0.4% by weight or less, which is suitable for use in the method of the present invention, if the metal powder is less than 3 μm, or it will be expensive if available. If the amount exceeds the above range, the sinterability of the raw material powder to which the C powder is added is reduced.

In the method for producing a sintered body according to the present invention, the metal powder containing C added to the raw material powder usually has a C content of 0.05 to 0.4% by weight of the mixed powder obtained by addition. C is added at 0.1% by weight in the sintering process
Hereinafter, the C content can be appropriately determined so as to obtain a sintered body containing 0.2 or 0.3% by weight or less of oxygen.

In the present invention, after a mixed powder is obtained by adding a metal powder containing C, a known method is performed, but the sintered body to be produced has a C content of 0.1% by weight. Or less, and the oxygen content is 0.2% by weight or less, or
The content is 3% by weight or less, and the desired effect cannot be obtained outside these ranges. Furthermore, the relative density is 9
Since it needs to be 2% or more, conditions suitable for producing such a sintered body are adopted.

As the molding method in the present invention, compression molding by press, injection molding powder metallurgy, and the like can be applied. However, in injection molding powder metallurgy, a large amount of binder is required. It is preferable to use a binder which is difficult, for example, a binder mainly composed of wax. Further, sintering requires an atmosphere such as a vacuum atmosphere or a hydrogen atmosphere which is a non-oxidizing atmosphere, in which a CO generation reaction between C and oxygen is promoted.

[0021]

Next, an embodiment of the present invention will be described.

Example 1 Pure Fe powder (average particle size 6 μm, oxygen content 0.35% by weight) and Ni powder (average particle size 6 μm, oxygen content 0.25%)
Wt%) and Fe-1.0 wt% C powder (average particle size 6μ)
m, oxygen content 0.30% by weight)
After obtaining a mixed powder containing 6% by weight and 0.1% by weight of C and the balance being Fe and containing 0.31% by weight of oxygen as an unavoidable impurity, 1.5% of paraffin wax was mixed as a lubricant. Then, the mixed powder obtained at a pressure of 1500 kgf / cm ² was compression-molded, and the obtained compression-molded body (diameter 20 mm, thickness 10 mm) was sintered at 1300 ° C. for 1 hour in a vacuum to obtain an invar sintered body. Manufactured. For the produced amber sintered body, the C content and the oxygen content were determined by chemical analysis, the relative density was determined by a hydrometer, and the coefficient of thermal expansion from room temperature to 100 ° C. was determined by a thermal dilatometer.
In addition, the weldability was measured by TIG welding.
Table 1 shows the results. The weldability was good.

Example 2 The composition contains 34% by weight of Ni and 0.1% by weight of C, the balance being substantially composed of Fe, and oxygen as an inevitable impurity.
Except that a mixed powder containing 31% by weight was obtained, the same treatment as in Example 1 was performed to produce an invar sintered body, and various tests were performed as in Example 1. Table 1 shows the obtained results. The weldability was good.

Example 3 The composition contains 39% by weight of Ni and 0.1% by weight of C, and the balance substantially consists of Fe.
Except that a mixed powder containing 31% by weight was obtained, the same treatment as in Example 1 was performed to produce an invar sintered body, and various tests were performed as in Example 1. Table 1 shows the obtained results. The weldability was good.

Example 4 A mixed powder containing 36% by weight of Ni and 0.25% by weight of C with the balance being substantially Fe and containing 0.30% by weight of oxygen as an unavoidable impurity was obtained. An invar sintered body was manufactured in the same manner as in Example 1, and various tests were performed in the same manner as in Example 1. Table 1 shows the obtained results.
The weldability was good.

Example 5 A mixed powder was obtained in the same manner as in Example 1, a wax-based binder was added so that the volume ratio of the mixed powder to the wax-based binder was 60:40, and the mixture was kneaded at 150 ° C. And then granulated into pellets. The obtained pellet was injection-molded using an injection molding machine, and the obtained injection-molded product was kept at 300 ° C. for 2 hours to remove the wax binder. The obtained injection molded article (diameter 20 mm, thickness 10
mm) was sintered in vacuum at 1320 ° C. for 1 hour to produce an invar sintered body. Various tests were performed on the manufactured amber sintered body in the same manner as in Example 1. Table 1 shows the obtained results. The weldability was good.

Comparative Example 1 The procedure of Example 5 was repeated except that Fe-1.0 wt% C powder was not added as an additive to the raw material powder, and various tests were performed in the same manner as in Example 1. went. Table 1 shows the obtained results. The weldability was good.

COMPARATIVE EXAMPLE 2 The composition contains 32% by weight of Ni and 0.1% by weight of C, with the balance being substantially composed of Fe.
Except that a mixed powder containing 31% by weight was obtained, an invar sintered body was manufactured in the same manner as in Example 5, and various tests were performed in the same manner as in Example 1. Table 1 shows the obtained results. The weldability was good.

COMPARATIVE EXAMPLE 3 Ni was contained in an amount of 41% by weight and C in an amount of 0.1% by weight, and the balance was substantially composed of Fe.
Except that a mixed powder containing 30% by weight was obtained, the same treatment as in Example 5 was performed to produce an invar sintered body, and various tests were performed as in Example 1. Table 1 shows the obtained results. The weldability was good.

Comparative Example 4 The procedure of Example 5 was repeated except that the amount of the Fe-1.0% by weight C powder added to the raw material powder was increased and the C content was changed to 0.55% by weight. And performed various tests.
Table 1 shows the obtained results. The weldability was poor.

[0031]

[Table 1]

From these results, (1) all of the amber sintered bodies of Examples 1 to 5 had a C content of 0.1% by weight or less and an oxygen content of 0.2% by weight or less, It has a density of 92% or more, a thermal expansion coefficient of 3 × 10 ⁻⁶ or less, and is sufficiently low that the invar sintered body does not expand practically. (2) Since the oxygen content of the amber sintered body of Comparative Example 1 is as high as 0.24% by weight and the relative density is as low as 85.5%, the mechanical strength is inferior to that of the smelted material. (3) Comparative Example 2,
The invar sintered body of No. 3 has a high thermal expansion coefficient of 4 × 10 ⁻⁶ / ° C. because the Ni content is out of the range of 33 to 40%, and exceeds the extent that the invar sintered body does not expand practically. ing. (4) The invar sintered body of Comparative Example 4 had poor weldability because the amount of C powder added was too large and the C content after sintering was too large at 0.17% by weight. . Some disadvantages are observed.

Example 6 Pure Fe powder (average particle size 6 μm, oxygen content 0.35% by weight) and Ni powder (average particle size 6 μm, oxygen content 0.2)
5% by weight), Co powder (average particle size 5 μm, oxygen content 0.35% by weight), Fe-1.0% by weight C powder (average particle size 6 μm, oxygen content 0.30% by weight) Using 32% by weight of Ni, 6% by weight of Co and 0.1% of C.
After obtaining a mixed powder containing 1% by weight and the balance substantially consisting of Fe and containing 0.31% by weight of oxygen as an unavoidable impurity, 1.5% paraffin wax was mixed as a lubricant and then mixed with a mold. Fill, press force 1500kgf / cm
² was compression molded. The obtained compression molded body (diameter 20
mm, thickness 10 mm) was sintered in vacuum at 1320 ° C. for 1 hour to produce a superamber sintered body. Various tests were performed on the manufactured Super Amber sintered body in the same manner as in Example 1. In particular, the coefficient of thermal expansion is 25 to 100 ° C,
The measurement was also performed for each of -200C, -300C, -400C, and -500C. Table 2 shows the results. Compared with the comparative example in which C powder was not added to the raw material powder, it was recognized that both the relative density and the coefficient of thermal expansion were significantly improved, and the weldability was also good.

Example 7 The same treatment as in Example 1 was carried out except that the C content of the raw material powder was 0.25% by weight and the sintering atmosphere was a hydrogen atmosphere.
Various tests were performed on the obtained product in the same manner as in Example 6. Table 2 shows the obtained results. Compared with the comparative example in which C powder was not added to the raw material powder, it was recognized that both the relative density and the coefficient of thermal expansion were significantly improved, and the weldability was also good.

Example 8 A 42% by volume wax-based binder was added to the raw material powder of Example 6, kneaded at 150 ° C. and granulated into pellets, which were injected using an injection molding machine. The molded body was further held at 300 ° C. for 2 hours to perform a binder removal treatment. Thereafter, a baking treatment was performed at 1320 ° C. for 1 hour. Various tests were performed on the obtained product in the same manner as in Example 6. Table 2 shows the obtained results. Compared with the comparative example in which C powder was not added to the raw material powder, it was recognized that both the relative density and the coefficient of thermal expansion were significantly improved, and the weldability was also good.

Comparative Example 5 The same treatment as in Example 6 was carried out except that Fe-1.0% by weight C powder was not used as a raw material powder. Ni was 32% by weight, Co was 6% by weight, and the balance was A mixed powder substantially consisting of Fe was obtained. This mixed powder was treated as in Example 6. Various tests were performed on the obtained product in the same manner as in Example 6. Table 2 shows the obtained results. It was recognized that both the relative density and the coefficient of thermal expansion were significantly inferior to the examples in which the C powder was added to the raw material powder, and the weldability was also poor.

Comparative Example 6 The same treatment as in Example 6 was carried out except that the mixing amount of the Fe-1.0% by weight C powder as the raw material powder was increased to make the C content 0.55% by weight. 32% by weight Ni, 6% Co
A mixed powder consisting essentially of Fe by weight and the balance substantially consisting of Fe was obtained.
This mixed powder was treated as in Example 6. Various tests were performed on the obtained product in the same manner as in Example 6. Table 2 shows the obtained results. It was recognized that both the relative density and the coefficient of thermal expansion were significantly inferior to the examples in which the C powder was added to the raw material powder, and the weldability was also poor.

Comparative Example 7 An alloy having a composition similar to that of Comparative Example 5 was melted according to a conventional method, and then a sintered body was manufactured by plastic working. A test piece cut out from the obtained material was used in the same manner as in Example 6. Various tests were performed. Table 2 shows the obtained results. From these results, it can be seen that although the relative density shows a good value, only the ingot having a value inferior to the example of the present invention in the thermal expansion coefficient is obtained.

[0039]

[Table 2]

Example 9 Pure Fe powder (average particle diameter 6 μm, oxygen content 0.35% by weight) and Ni powder (average particle diameter 6 μm, oxygen content 0.2)
5% by weight) and Fe-50% by weight Co powder (average particle size 1).
3 μm, oxygen content 0.31% by weight) and Fe-1.0
Wt% C powder (average particle size 5 μm, oxygen content 0.30 wt%) using 29 wt% Ni, 16 wt% Co and 0.1 wt% C, with the balance being substantially To Fe
After obtaining a mixed powder containing 0.30% by weight of oxygen as an unavoidable impurity, 1.5% paraffin wax was mixed as a lubricant, and the pressure was increased to 1500 kgf / cm.
² was compression molded. The obtained compression molded body (diameter 20
mm, thickness 10 mm) was sintered in vacuum at 1320 ° C. for 2 hours to produce a Kovar sintered body. Various tests were performed on the manufactured Kovar sintered body in the same manner as in Example 1. In particular, regarding the coefficient of thermal expansion, 25 to 300 ° C.,
° C, ~ 450 ° C, and ~ 500 ° C. Table 3 shows the results. The weldability was good.

Example 10 29% by weight of Ni, 16% by weight of Co and 0.2% of C
Except that a mixed powder containing 7% by weight, the balance being substantially Fe, and containing 0.30% by weight of oxygen as an unavoidable impurity was obtained, the same treatment as in Example 9 was carried out. Various tests were performed. Table 3 shows the obtained results. In addition,
The weldability was good.

Example 11 After a mixed powder was obtained in the same manner as in Example 9, a wax-based binder was added so that the volume ratio of the mixed powder to the wax-based binder was 55:45, and the mixture was kneaded at 150 ° C. And then granulated into pellets. The obtained pellet was injection-molded using an injection molding machine, and the obtained injection-molded product was kept at 300 ° C. for 2 hours to remove the wax binder. The obtained injection molded article (diameter 20 mm, thickness 10
mm) in vacuum at 1320 ° C. for 2 hours to produce a Kovar sintered body. Various tests were performed on the manufactured Kovar sintered body in the same manner as in Example 9. Table 3 shows the obtained results. The weldability was good.

Comparative Example 8 The same treatment as in Example 11 was carried out except that Fe-1.0% by weight C powder as an additive to the raw material powder was not added.
Various tests were performed similarly. Table 3 shows the obtained results. The weldability was good.

Comparative Example 9 The procedure of Example 11 was repeated, except that the amount of the Fe-1.0% by weight C powder added to the raw material powder was increased and the C content was changed to 0.38% by weight. The test was performed and various tests were similarly performed. Table 3 shows the obtained results. The weldability was poor.

COMPARATIVE EXAMPLE 10 As in the prior art, a Kovar alloy was melt-cast and Ni was
Ingot containing 16% by weight of Co and 16% by weight of Co, with the balance being Fe and unavoidable impurities.
An ingot sample having a thickness of 10 mm and a thickness of 10 mm was collected and subjected to various tests in the same manner as in Example 9. Table 3 shows the obtained results.
The weldability was good.

[0046]

[Table 3]

From these results, (1) Examples 9 to 11
All of the Kovar sintered bodies have a C content of 0.1% by weight or less, an oxygen content of 0.3% by weight or less, a relative density of 94% or more, 25 ° C to 300 ° C, 400
The coefficients of thermal expansion up to 500 ° C., 450 ° C., and 500 ° C. are very close to the coefficients of thermal expansion of ingots having the same coefficient of thermal expansion as hard glass and ceramic. (2) The Kovar sintered body of Comparative Example 8 has an oxygen content of 0.31% by weight.
Since the relative density is as low as 85.4%, the mechanical properties are inferior to those of the ingot. (3) In the Kovar sintered body of Comparative Example 9, the amount of C powder added was too large and the C content was 0.13.
Since the content was too large at 8% by weight, the weldability was poor.
Disadvantages such as were recognized.

[0048]

According to the present invention, since a metal powder containing C is added, a good invar and superamber sintered product having a relative density of 92% or more and an extremely low coefficient of thermal expansion, Further, a Kovar sintered product having a thermal expansion coefficient comparable to that of hard glass or ceramic can be produced very easily, and a remarkable effect is recognized.

Claims (9)

[Claims] 1. The composition contains 33 to 40% by weight of Ni, and the balance substantially consists of Fe.
A metal powder containing C is added to a raw material powder containing not less than 0.1% by weight, and the obtained mixed powder is molded. Then, the mixture is sintered in a non-oxidizing atmosphere. 2% by weight
A method for producing a sintered body, comprising: obtaining a sintered body having a relative density of 92% or more. 2. The composition contains 33 to 40% by weight of Ni, and the balance substantially consists of Fe.
A metal powder containing C is added to a raw material powder containing not less than% by weight, a binder is added to the obtained mixed powder to prepare a kneaded product, and the kneaded product is injection-molded. After sintering, the content of C is 0.1% by weight or less, and the content of oxygen is
A method for producing a sintered body, comprising obtaining a sintered body containing 2% by weight or less and having a relative density of 92% or more. 3. Ni is 33 to 40% by weight and Co is 5 to 7%.
% By weight, the balance being substantially Fe, the metal powder containing C added to the raw material powder containing 0.1% by weight or more of oxygen as an unavoidable impurity, and the resulting mixed powder is molded and then non-oxidized. Sintering in a neutral atmosphere, containing 0.1% by weight or less of C and 0.2% by weight or less of oxygen, and having a relative density of 92% or less.
% Of a sintered body, characterized by obtaining a sintered body of not less than 10%. 4. Ni is 33 to 40% by weight and Co is 5 to 7%.
Wt.%, With the balance substantially consisting of Fe, a metal powder containing C added to a raw powder containing 0.1 wt.% Or more of oxygen as an unavoidable impurity, and a binder added to the resulting mixed powder and kneaded. After the mixture is injection-molded, the mixture is sintered in a non-oxidizing atmosphere to make C 0.1% by weight.
Hereafter, the oxygen content is 0.2% by weight or less, and the relative density is 9% or less.
A method for producing a sintered body, comprising obtaining a sintered body of 2% or more. 5. 28 to 32% by weight of Ni and 15 to 25% of Co
Raw material powder containing 18% by weight, the balance being substantially Fe, and containing 0.1% by weight or more of oxygen as an inevitable impurity,
After adding a metal powder containing C and shaping the resulting mixed powder, sintering is performed in a non-oxidizing atmosphere to contain 0.1% by weight or less of C, 0.3% by weight or less of oxygen, and Density is 92
% Of a sintered body, characterized by obtaining a sintered body of not less than 10%. 6. 28 to 32% by weight of Ni and 15 to 25% of Co
Raw material powder containing 18% by weight, the balance being substantially Fe, and containing 0.1% by weight or more of oxygen as an inevitable impurity,
A metal powder containing C is added, and a binder is added to the obtained mixed powder to prepare a kneaded material. After the kneaded material is injection-molded, the mixture is sintered in a non-oxidizing atmosphere to reduce C to 0.1. A method for producing a sintered body, comprising obtaining a sintered body containing 1% by weight or less, 0.3% by weight or less of oxygen, and having a relative density of 92% or more. 7. The method for producing a sintered body according to claim 1, wherein the non-oxidizing atmosphere is a vacuum atmosphere or a hydrogen atmosphere. 8. The method for producing a sintered body according to claim 1, wherein the raw material powder contains 0.6% by weight or less of oxygen. 9. The metal powder to be added to the raw material powder is Fe-
The method for producing a sintered body according to any one of claims 1 to 8, wherein C is C and the amount of addition is 5 to 50% by weight.