JP2006342374A - Method for producing sintered metal and alloy - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a metal sintered compact and an alloy sintered compact which are used for a tool material for working and a turbine for a boiler in a thermal field. <P>SOLUTION: In this manufacturing method, when manufacturing a metal or an alloy by sintering, powder of the metal and powder of the alloy are subjected to preforming. The resultant preform is enveloped in a capsule made of metal to which an exhaust tube is attached, and the capsule is set in a furnace. While depressurizing the inside of the capsule via the exhaust tube from the outside of the furnace, the inside of the furnace is kept at an atmospheric pressure and temperature raising is done up to a prescribed sintering temperature to carry out sintering, or, after the temperature raising, sintering is performed under a low pressure of 0.08 to 5 MPa. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a metal used for a tool for processing that requires wear resistance, thermal shock resistance, crack resistance, seizure resistance, mechanical strength in a steel and non-ferrous metal industry, a turbine for a boiler in a thermal field, and the like. The present invention relates to a method for producing an alloy sintered body.

  Iron-base alloy materials having excellent wear resistance are used for rolling, forming and cutting of metal materials and non-ferrous metal materials. These machining tools are usually manufactured by casting or the like. However, in order to greatly improve the durability, it is necessary to deposit a large amount of hard carbide or ceramic such as oxide. Yes, cannot be manufactured. In order to achieve this, a manufacturing method for sintering powders of iron-based alloys and the like has been found. In this powder sintering method, the structure after sintering can be made fine depending on the particle size of the powder used, and in addition to wear resistance, toughness and the like can be improved. Usually, in the production by these powder sintering methods, in order to reliably obtain a high-density material with few pores after sintering, a method of sintering under high temperature and high pressure is common.

  Regarding a conventional powder sintering method, Patent Document 1 describes a composite member in which an outer layer made of an abrasion-resistant material is provided on a steel base. As a specific manufacturing method, a mixed powder of iron-base alloy powder and ceramic fiber is filled into a capsule, and the capsule is covered with an iron lid, welded, vacuum degassed and vacuum sealed, A method of manufacturing by sintering by hydraulic forming (HIP) is described. In this example, a steel member having a high density and excellent wear resistance and crack resistance is obtained by the HIP method.

  With respect to this HIP method, Patent Document 2 describes a method in which a metal mold is filled with powder, a glass powder is placed on the mold, heated and degassed in a vacuum, and subjected to HIP treatment as it is. Patent Document 3 describes a method for producing a high alloy steel sintered material, in which a high speed powder is preformed and subjected to HIP treatment at 10 MPa after sintering. On the other hand, Patent Document 4 discloses a low-pressure sintering method in place of the HIP treatment, but it is limited to a fiber-reinforced one.

Even in the above-mentioned 1 to 3 publications, in order to obtain a high-density powder sintered body, although the intermediate process such as the type of powder, the molding method, and the sintering process is different, the ultra high pressure of 10 to 100 MPa is finally obtained Sintered body is obtained through the HIP process which requires. Since this HIP method generates a high pressure at a temperature of 1000 ° C. or higher, the apparatus itself is very expensive, and the volume in the furnace is also a high-pressure apparatus, so there is a limit to the enlargement of the apparatus itself. For this reason, since the amount and size of the workpieces that can be loaded in the furnace are limited, the production cost is inevitably high, and therefore, the appearance of a process that can be sintered at low cost is indispensable.
JP 2001-59147 A JP 54-48613 A JP-A-62-287041 JP 2003-119554 A

  The present invention has been made in view of such problems, and an object of the present invention is to produce metals and alloys for high durability members, processing tool materials, cutting tools, and boiler turbines in the thermal field at low cost. And providing a new manufacturing technique for that purpose.

As a result of diligently examining the above problems, the present invention improves the problems of the conventional high-cost HIP method, and uses a normal atmospheric furnace to depressurize the inside of the container enclosing the sample with low isotropic pressure. A method of sintering (Low Isostatic Pressing sintering: LIP method) has been developed. In this sintering method, the degree of adhesion between powders is increased by pressurization, and the denseness is promoted because no gas remains, and isotropic pressure pressurization is performed under a low pressurization of 0.08 to 5 MPa. Therefore, it has been found that the characteristics of the sintered body are isotropic and that there are various advantages such as no special equipment is required even for large parts.
First, the relationship between the Vickers hardness, the sintering holding temperature, and the porosity of the sintered body in the LIP method will be described.
As a test material, high-speed steel (C: 0.1% by mass, Cr, V, Mo, W: 2-6% by mass, remaining Fe and unavoidable impurities) powder having a particle size of 15 μm was TIG welded at one end. Filled and sealed in a thin stainless steel foil pipe having a thickness of 100 μm and sintered at a holding temperature in a nitrogen atmosphere furnace while deaeration with a diffusion pump. While the obtained sintered body was observed with an SEM, the degree of sintering was evaluated by Vickers hardness.
FIG. 1 shows the relationship between Vickers hardness and holding temperature when sintered by the LIP method using a diffusion pump. When the sintering temperature was 1373K, the degree of sintering was low at about Hv100, but the hardness increased as the holding temperature was increased, and when the temperature exceeded 1500K, the increase in hardness increased sharply, but at 1523K and higher, it was almost constant. You can see that FIG. 2 shows an SEM image of the sintered body by the LIP method. When (a) is sintered at 1473K using a rotary pump, (b) is sintered at 1523K using a diffusion pump. 2 (a) and 2 (b), the white phase indicates carbides, and the black portion indicates voids. In (a), quite a lot of voids are seen, but in (b) almost no voids are seen. In actual measurement, the porosity (area ratio) of (a) was 3.67%, and (b) was 0.31%. This decrease in porosity makes it easier for the powder to be deformed by raising the holding temperature, the degree of adhesion between the powders increased, the residual gas decreased, the iron diffusion became active, etc. It is considered that the sinterability was improved.
FIG. 3 shows the relationship between porosity and Vickers hardness. For comparison, the values of samples sintered by the HIP method are also shown. It can be seen that the Vickers hardness increases as the porosity decreases in sintering by the LIP method. The tendency is particularly remarkable when the porosity is 1%, but it is also understood that the hardness hardly changes when the porosity is 0.3% or less. In the case of sintering by the HIP method, the porosity was reduced to 0.056%, and as a result of observing the structure of the sintered body, the particle size of the carbide was smaller than that of the LIP method. From this fact, the hardness of the sintered body obtained by the LIP method is slightly lower than that of the HIP method sintered body because large carbides are dispersed. It is considered equivalent.
As described above, the porosity of the LIP method sintered body according to the present invention decreases as the holding temperature becomes higher or the vacuum becomes higher and the residual gas decreases. Therefore, by setting the processing conditions appropriately, a good sintered body equivalent to HIP sintering can be obtained even in LIP method sintering.
The present invention has been made based on the above findings, and the gist thereof is as follows.
(1) When the metal and alloy are produced by sintering, the metal and alloy powder are preformed, and then the preform is wrapped in a metal foil capsule with an exhaust pipe and placed in a furnace. A metal characterized in that the inside of the capsule is decompressed to 0.08 MPa or less from the outside of the furnace through an exhaust pipe, and the inside of the furnace is heated, sintered, or heated to a predetermined sintering temperature at atmospheric pressure. And a method for producing an alloy sintered body.
(2) The method for producing a metal and alloy sintered body according to (1), wherein the furnace is heated to a pressure of 0.08 to 5 MPa after the temperature is raised to the sintering temperature.
(3) When the metal and alloy are manufactured by sintering, after the metal and alloy powder is preformed, the preform is wrapped in a metal foil capsule having one or more holes, and the holes are made of glass. Cover with powder or a glass plate, raise the temperature to a predetermined sintering temperature under a reduced pressure of 0.08 MPa or less to bring the glass into a molten state, and then sinter under a low pressure of 0.08 to 5 MPa. A method for producing a sintered metal and alloy product.
(4) The method for producing a sintered metal and alloy according to any one of (1) to (3), wherein the thickness of the metal foil of the capsule is 5 to 300 μm.
(5) When the temperature is raised to a predetermined sintering temperature under reduced pressure, the temperature is once raised to a temperature 25 to 100 ° C. higher than the predetermined sintering temperature, and sintering is performed at the predetermined sintering temperature. The method for producing a sintered metal and alloy according to any one of (1) to (4).
(6) When the metal and alloy are produced by sintering, the metal and alloy powder are preformed, and then the preform is coated with glass powder, and the temperature is raised to a predetermined temperature under a reduced pressure of 0.08 MPa or less. A method for producing a sintered metal and alloy, characterized in that the glass powder is melted by heating and then sintered under a low pressure of 0.08 to 5 MPa.
(7) The method for producing a sintered metal and alloy according to any one of (1) to (6), wherein a molding pressure during the preforming is 50 to 1000 MPa.
(8) Any one of (1) to (7), wherein the glass has a softening point of 600 ° C. to 1000 ° C., and the glass has a melt viscosity of 10 ² to 10 ⁵ Pa · s at 1100 ° C. A method for producing a sintered metal and alloy according to item 1.
(9) The metal and alloy sintered body is an iron-based alloy, nickel, a nickel-based alloy, cobalt, or a cobalt-based alloy, and the predetermined sintering temperature is 900 to 1250 ° C. (1 The manufacturing method of the metal and alloy sintered compact of any one of (8)-(8).
(10) The metal and alloy sintered body is titanium or a titanium-based alloy, and the predetermined sintering temperature is 1000 to 1350 ° C. Any one of (1) to (8) The manufacturing method of the metal and alloy sintered compact of description.
(11) The metal and alloy sintered body is aluminum, an aluminum-based alloy, magnesium, or a magnesium-based alloy, and the predetermined sintering temperature is 250 to 550 ° C. (1) or (2) The manufacturing method of the metal and alloy sintered compact as described in 1).

  According to the metal and alloy sintered body manufacturing method of the present invention, high durability materials such as a tool material for machining that can improve wear resistance, toughness, and mechanical strength, and a turbine for a boiler in the thermal field are made high. Instead of costly HIP process, it can be manufactured at low cost.

  Metal and alloy sintered bodies according to the present invention basically refer to iron-base alloys, cobalt, cobalt alloys, nickel, nickel-base alloys, titanium, titanium alloys, aluminum, aluminum-base alloys, magnesium, magnesium-base alloys, and these The manufacturing method can be manufactured by the following three methods. First, in the method according to the first embodiment of the present invention (hereinafter also simply referred to as the first method), a metal and an alloy gold powder are subjected to a granulation step as necessary, and then preformed. This pre-molding is preferably powder pressure molding used in ordinary powder molding, and a uniaxial press or a cold isostatic press (CIP) can be used as appropriate. Further, in order to obtain a preformed body efficiently, an organic wetting agent, lubricant, binder, etc. may be added to the metal and alloy powder as long as they do not adversely affect the sintering. The obtained preform is subjected to some processing as required, and then the entire surface portion of the preform is coated with glass powder.

  The glass powder is coated as uniformly as possible on the entire surface of the preform by brushing, spraying, or dipping a pre-powdered glass dispersed in a non-aqueous organic solvent such as alcohol. The coating thickness varies depending on the average particle diameter and the particle size distribution of the glass powder, but it should be at least about 100 μm as a rough guide. Below this, when the preform is sintered, a non-glass coating layer or a minute pinhole may be formed.

As shown in FIG. 6, the preform molded with glass powder is placed in a furnace and heated to a predetermined sintering temperature corresponding to the metal and alloy under reduced pressure. The reduced pressure is indispensable for preventing the oxidation of the metal and alloy powder and at the same time, promoting the sintering promotion by removing the air present in the voids in the preform. The degree of pressure reduction, the better high but may be any generally 10 ^-1 Pa or less. The preform starts shrinking in volume during the temperature rise and begins to sinter to some extent when it reaches a predetermined sintering temperature according to the metal and alloy. At the same time, the glass powder layer is softened by heating and is completely melted in a predetermined sintering temperature range corresponding to the metal and alloy to completely cover the entire surface of the preform. In a predetermined sintering temperature range corresponding to the metal and alloy in which the glass is in a molten state, although the preform has been sintered, it has been difficult to obtain a complete dense body.

  Therefore, in the present invention, sintering is promoted by applying a slight external pressure to the preform. That is, since the surface of the preform is completely covered with molten glass, the gas pressure can be uniformly applied to the entire surface of the preform by switching to a pressurized atmosphere. Further, since the inside of the pre-formed body has almost no gas components such as air due to the above-described decompression, this gas pressure load effect is promoted. However, in the present invention, an ultrahigh pressure of 10 MPa to 100 MPa is unnecessary at a high temperature of 1000 ° C. or higher as in the conventional HIP method. Although the pressing value varies depending on the type and amount of metal and alloy powder, sintering can be performed at a low pressure of about 0.08 to 5 MPa. The data that the higher the pressurization value is better is known from the pressure of the HIP process, but the purpose of the present invention is to obtain a high-quality durable tool material at a low cost. The upper limit of the value is 5 MPa or less. Sintering by this low pressure method is due to the property that metals can be easily plastically deformed at high temperatures. That is, when the metal and alloy are iron-based alloy, cobalt, cobalt alloy, nickel, nickel-based alloy, 900 to 1250 ° C., and when the metal and alloy are titanium or titanium-based alloy, 1000 Metals and alloy powders that have reached a sintering temperature of ˜1350 ° C. can be densified by filling the residual pores with external pressure as a driving force if a slight external pressure is applied to the compact. Become. If the lower limit of the sintering temperature is 900 ° C. or less than 1000 ° C., sintering under low pressure is insufficient, which is not preferable. Moreover, even if the upper limit is 1250 ° C. or above 1350 ° C., the crystal grains of the sintered material become coarse and the characteristics deteriorate, which is not preferable.

  As shown in FIG. 4, the method according to the second embodiment of the present invention (hereinafter also simply referred to as the second method) is a capsule-shaped metal prepared from a preform formed in the same manner as the first invention. Install in foil. An exhaust pipe for deaeration is attached to this metal foil. This operation can be performed by a method such as welding. Next, the preform formed in the metal foil is placed in a furnace. A tube extending from the metal foil is connected to a vacuum pump. The temperature is raised while degassing the inside of the metal foil with a vacuum pump. When a predetermined sintering temperature corresponding to the metal and alloy is reached, the metal foil is in a reduced pressure state, so that the atmospheric pressure in the furnace is applied to the entire surface of the preform and densification occurs. Alternatively, after reaching this temperature range, if the furnace is loaded with a gas pressure of 0.08 to 5 MPa from the atmospheric atmosphere into the furnace, sintering proceeds further due to plastic deformation of the metal as in the first method, and the time is short. A dense body can be obtained.

  In the second method, unlike the first method, the means for coating the preform with glass is not used. For this reason, as the metal and alloy, in addition to the metal and alloy exemplified in the first method as described above, the melting point is lower than the softening point of normal glass, such as aluminum, aluminum-based alloy, magnesium, magnesium-based alloy, etc. The present invention can be applied to such a low melting point metal. When such metals and alloys are low melting point materials, the sintering temperature needs to be 250-550 ° C. If the sintering temperature is lower than the lower limit of 250 ° C., sintering under low pressure is insufficient, and if the upper limit is higher than 550 ° C., the crystal grains of the sintered material become coarse and the characteristics deteriorate, which is not preferable. .

  As shown in FIG. 5, the method according to the third embodiment of the present invention (hereinafter also simply referred to as the third method) is a method in which the preform is placed in a capsule-shaped metal foil and welded or the like. Block from outside air by means. Here, one or more small holes (through holes) are made in the metal foil. This hole is for degassing the gas contained in the preform. Further, this hole is covered with a glass powder layer or a glass piece (which may be porous). In this state, the molded body together with the metal foil is placed in a furnace, and the temperature is raised to a predetermined sintering temperature corresponding to the metal and alloy under reduced pressure.

  Gases such as air in the preform or in the gap between the metal foil and the preform are the gap between the glass powder or the gap between the glass piece and the metal foil (in the case of porous glass). , Including glass holes). As the temperature rises, the glass softens and eventually reaches a molten state. This closes the small hole in the metal foil. In this way, the gas in the preform is almost gone before it is closed by the molten glass. In this state, low pressure pressurization of 0.08 to 5 MPa is performed for sintering. Even in the third method, a dense sintered body can be obtained while the pressure is lower than that in the HIP method.

  In the above three methods, the preform is desirably a high-density body. This is also important to assist low pressure sintering. As a method for obtaining a preform, both uniaxial press and CIP molding can be used, and the molding pressure is 50 to 1000 MPa as a practical range. If the molding pressure is less than 50 MPa, the green density of the preform is lowered, and even if low pressure is applied for a long time, complete sintering becomes difficult. Conversely, if the molding pressure is set to exceed 1000 MPa, it is advantageous in that the density of the molded body obtained (in other words, the relative density with respect to the theoretical density) is high, but this is due to an increase in the size of the molding apparatus and an increase in equipment costs. The problem of cost increase arises. If it is the range of 50-1000 MPa, a shaping | molding apparatus will also be comparatively compact and can respond also to mass production.

  The glass used in the first or third method of the present invention is extremely important. Glass melts through the softening point when heated. If the softening point of the glass is too low, the glass falls into a molten state before the densification of the molded body proceeds to some extent. In a state where sintering of the molded body does not proceed to some extent, a large number of coarse pores remain in the molded body. Therefore, in the glass having a low softening point, the molten glass is impregnated into the molded body and adversely affects the properties of the metal and alloy. On the contrary, when the glass has a remarkably high softening point, if the glass is in a semi-molten state or not melted in the sintering temperature range of the molded product, that is, in the range of 1000 to 1300 ° C., the glass coating of the molded product is incomplete Thus, even if the gas pressurization is switched to the next, the gas penetrates into the molded body, so that sintering becomes difficult. The high-temperature characteristics of this glass are the same even when the preform is entirely covered and when the glass powder, glass plate, and porous glass are used to block the holes attached to the metal foil.

For the above reasons, the softening point of the glass used in the method for producing a sintered metal and alloy according to the present invention is 600 ° C. to 1000 ° C., and the melt viscosity value at 1100 ° C. of the glass is 10 ² to 10 ⁵ Pa. The range of s is preferable. If the relative density of the preformed body is approximately 50% or more, the glass having the softening point of the glass specified here and the melt viscosity value at 1100 ° C. can be used. In addition, the glass used for this invention is prescribed | regulated only by the softening point and the melt viscosity value of 1100 degreeC to the last, and is limited by the chemical composition of glass, for example, a borosilicate glass system, an aluminosilicate glass, etc. It is not a thing. Further, the glass defined in the present invention may be a material containing a crystalline component and an amorphous component as well as a completely amorphous material. For aluminum, magnesium, and alloys thereof having a low sintering temperature, glass that melts at a low temperature must be selected.

  In the first method to the third method of the present invention, when the preform is sintered at a predetermined sintering temperature corresponding to the metal and alloy, in order to improve the sinterability, the desired sintering temperature is used. Once the temperature is raised to a temperature higher by 25 to 100 ° C., the main sintering is performed, whereby the sinterability can be achieved without coarsening the crystal grains. If this temperature is less than 25 ° C., the expected effect of improving sinterability cannot be obtained, and if it exceeds 100 ° C., it is too high and the crystal grains of the sintered material become coarse, which is not preferable. In this case, the temperature raising time is preferably 5 to 30 minutes. If it is less than 5 minutes, the expected improvement effect cannot be obtained, and in the case of a long-time treatment over 30 minutes, the crystal grains of the sintered material become a raw material due to the synergistic effect of high temperature and long treatment time, which adversely affects the properties. Because.

  As the metal foil for capsules, ordinary steel, stainless steel, and the like can be appropriately used as long as they have heat resistance in a predetermined sintering temperature range corresponding to a metal and an alloy and have mechanical strength to withstand handling. The metal foil is preferably as thin as possible so as not to inhibit low pressure sintering, but the thickness of a practical metal foil is generally 5 to 300 μm. If the thickness of the metal foil is extremely thick, such as 2 mm or more, the low pressure effect tends to be reduced. In the second method, the preform itself is covered with a metal foil. However, the pressure reducing pipe connected to the pressure reducing pump outside the furnace needs to be strong and thick enough not to be crushed by the operation of the pressure reducing pump. is there.

  The metals and alloys of the present invention include various metals such as iron-based alloys, nickel, nickel-based alloys, cobalt, cobalt-based alloys, superalloys, titanium, titanium-based alloys, aluminum, aluminum-based alloys, magnesium, magnesium-based alloys, Alloy powder can be used. The component composition of the iron-base alloy is 0.1 to 3.5% carbon, 2 to 7% Cr, 0 to 10% Mo, 0 to 20% W, 1 to 15% (V Nb, Ta, Ti, Zr, and Hf), one or more elements selected from 0, 10% Co, 0-5% Ni, and the balance being substantially Fe. preferable. When the C content of this alloy is as high as 0.8% or more, it is one of materials excellent in abrasion resistance, mechanical strength, heat resistance and the like particularly required for roll materials. When the amount of C is low, it is one of the materials excellent in wear resistance and high toughness required for cutting tools and the like. Furthermore, a superalloy such as Hastelloy, Inconel or Nimonic can be used as the Ni-based alloy, and a superalloy such as stellite can be used as the Co-based alloy.

  In the method for producing a sintered metal and alloy according to the present invention, when the entire sintered body is made of a metal or an alloy, only a necessary portion is a sintered body of a metal and an alloy, and the other portion is a conventional inexpensive metal or Also included are so-called composites made of alloys. When manufacturing a composite, for example, in a cylindrical object, there are combinations of metals and alloys whose interior is inexpensive, and metals and alloys obtained by sintering only the outer layer. In this case, it is possible to form a preformed body with a hollow cylinder, incorporate an alloy cylinder into the hollow portion, and simultaneously sinter the preform. The preformed material is simultaneously preformed around the solid shaft material. It is also possible. A composite structure manufactured through the above-described first to third methods and using the method of the present invention for at least a part of the sintered body is also within the scope of the present invention.

<Example 1>
As an example of an integral cylinder (guide roller), C: 0.88%, Si: 0.28%, Cr: 4.0%, V: 2.0%, Mo: 5.0%, W: 6 An iron-based alloy powder containing 0.0% was preformed in the range of molding pressure 50 to 750 MPa using a uniaxial press machine to obtain a preform of 120 mmφ × 90 mmL. An aluminosilicate glass powder having a softening point of 750 ° C., 1100 ° C. and a melt viscosity of 10 ³ Pas is uniformly coated to a thickness of about 200 μm by the dipping method on the entire surface of each molded body thus obtained. After drying for 5 hours, it was placed in a furnace. While maintaining the inside of the furnace at a reduced pressure of 0.1 Pa, the temperature was raised to 1200 ° C. in 3 hours.

Immediately after reaching 1200 ° C., the reduced pressure state was switched to a pressurized atmosphere (pressure: 0.5 MPa) by introducing gas. After maintaining in this state for 2 hours, the sintered compact was taken out after furnace cooling. The surface of the obtained cylinder was uniformly coated with a glass layer solidified after melting. The obtained sintered body was evaluated by measuring the relative density and observing the microstructure after sufficiently removing the glass layer by grinding. Also, this sintered body is ground, a guide roller of 80 mmφ × 70 mmL is made as a prototype, subjected to predetermined heat treatment (quenching, tempering), and the base hardness is adjusted to 80 to 85 in Shore hardness, and then the wear resistance And crack resistance were evaluated. Crack resistance is the wear depth after passing a certain amount of hot plain steel.Crack resistance is a color check on the surface of the roller after passing to check for cracks. The state of seizing on the roller surface after the material was visually observed and evaluated. Table 1 shows the evaluation results.
Here, reference numeral 5 is a sintered metal produced through the same sintering process without glass coating. The relative density in the table indicates the ratio to the theoretical density of the sintered body. In addition, the wear depth% is a relative ratio after No. 1 when the wear depth after the test is 100% in the wear resistance test when the guide roll is made of cast high-speed steel of No. 6. is there.
As is clear from Table 1, in the range sample of the present invention, the relative density of the sintered body is also densified to 99% or more, and the wear depth rate by the wear test is greatly improved compared to the cast high speed material, It can be seen that characteristics almost similar to those of the HIP material are obtained. In addition, in Ni-based and Co-based alloys other than iron-based alloys, the wear resistance and strength are significantly improved. Incidentally, densification progressed in the sample that was vacuum-sintered only without using the glass entire surface coating method, metal foil + depressurization method, metal foil + glass sealing method, and the relative density of the sintered body was 90%. The wear depth was 100% or more.
Further, in the sample group which is within the scope of the present invention, the occurrence of surface cracks after the wear test was smaller than that of the cast material and was almost the same as that of the HIP material. Also, the seizure phenomenon was slight compared with the cast material.

<Example 2>
As an example of a composite guide roll made of sintered metal only in the outer layer portion, the same alloy powder as in Example 1 is preformed by a CIP device at a molding pressure of 500 to 1000 MPa, and this is cut to have an inner diameter of 70φ and an outer diameter of 90φ. A hollow cylindrical shaped body was obtained. A steel cylinder was inserted into the hollow portion. The high-speed steel and the pre-formed body were given a size difference in consideration of the sintering shrinkage rate and the thermal expansion difference. This was put into a stainless steel capsule-like thin metal foil container having a thickness of 100 μm. This container was provided with an exhaust steel pipe. After sealing the container, it was placed in a furnace. The exhaust pipe was taken out of the furnace from the inside of the furnace, and an exhaust vacuum pump was connected thereto, and the temperature was raised to a predetermined 1175 ° C. while reducing the pressure. When the temperature reached 1175 ° C., sintering was attempted in two types: atmospheric pressure and gas pressurization (3 MPa). After the furnace cooling, the obtained sintered body had a structure in which the sintered metal part of the steel and the outer layer were integrally joined, and the sintered body was in a good state without any deformation or cracks. . The sintered metal part was evaluated in the same manner as in Example 1.
As is clear from Table 2, in the range sample of the present invention, the relative density of the sintered body was also densified to 99% or more, and the wear depth rate by the wear test was greatly improved compared to the cast high speed material, It can be seen that characteristics almost similar to those of the HIP material are obtained. In addition, in Ni-base and Co-base alloys other than iron-base alloys, the wear resistance and strength are greatly improved. Incidentally, densification progressed in the sample that was vacuum-sintered only without using the glass entire surface coating method, metal foil + depressurization method, metal foil + glass sealing method, and the relative density of the sintered body was 90%. The wear depth was 100% or more.
Further, in the sample group within the scope of the present invention, the occurrence of surface cracks after the wear test was less than that of the cast material, and almost the same as that of the HIP material. Also, the seizure phenomenon was slight compared with the cast material.
Nos. 8 to 10 show the results in the atmosphere (no pressurization), and No. 7 shows the results when sintered under a pressure of 3 MPa. The wear depth was shown as a relative ratio in the wear test in the same manner as in Table 1, assuming that the wear depth of the cast high-speed steel was 100%.

<Example 3>
As an example of the structure similar to Example 2, an alloy powder having the same composition as that of Example 2 was preformed at a molding pressure of 500 to 1000 MPa by a CIP device, and a hollow cylindrical molded body was obtained by cutting. The same steel cylinder as in Example 2 was inserted into this, and sealed in a capsule-like metal foil made of plain steel having a thickness of 150 μm. In addition, three through holes of about 0.5 mmφ were made in the metal foil. A glass powder layer was formed on one of the through holes, and a glass piece was placed on the other two. This was placed in a furnace and heated to 1175 ° C. under reduced pressure. After reaching 1175 ° C., the atmosphere was switched to a gas pressure atmosphere of 3 MPa and held for 3 hours. When the sample was taken out after cooling in the furnace, the hole in the metal foil was completely sealed with the glass layer solidified after melting, and the sintered metal part from which the glass layer was removed was completely densified.
As is clear from Table 3, in the range sample of the present invention, the relative density of the sintered body is also densified to 99% or more, and the wear depth rate by the wear test is greatly improved compared to the cast high speed material, It can be seen that characteristics almost similar to those of the HIP material are obtained. In addition, in Ni-base and Co-base alloys other than iron-base alloys, the wear resistance and strength are greatly improved. Incidentally, densification progressed in the sample that was vacuum-sintered only without using the glass entire surface coating method, metal foil + depressurization method, metal foil + glass sealing method, and the relative density of the sintered body was 90%. The wear depth was 100% or more.
Further, in the sample group within the scope of the present invention, the occurrence of surface cracks after the wear test was less than that of the cast material, and almost the same as that of the HIP material. Also, the seizure phenomenon was slight compared with the cast material.
The wear depth was shown as a relative ratio in the wear test in the same manner as in Table 1, assuming that the wear depth of the cast high-speed steel was 100%.

<Example 4>
As an example of a structure similar to Example 3, an alloy powder having the same composition as Example 3 was preformed at a molding pressure of 500 to 1000 MPa using a CIP device, and a hollow cylindrical molded body was obtained by cutting. The same steel cylinder as in Example 2 was inserted into this, and sealed in a steel capsule metal foil having a thickness of 150 μm. In addition, three through holes of about 0.5 mmφ were made in the metal foil. A glass powder layer was formed on one of the through holes, and a glass piece was placed on the other two. This was placed in a furnace and heated to a sintering temperature of 1175 ° C. under reduced pressure. Then, the temperature was further increased to 1225 ° C. in a short time, then returned to the main sintering temperature of 1175 ° C. and a gas pressure of 3 MPa. Switch to atmosphere and hold for 3 hours. When the sample was taken out after cooling in the furnace, the hole in the metal foil was completely sealed with the glass layer solidified after melting, and the sintered metal part from which the glass layer was removed was completely densified.
As is clear from Table 4, in the range sample of the present invention, the relative density of the sintered body was also densified to 99% or more, and the wear depth rate by the wear test was greatly improved compared to the cast high speed material, It can be seen that characteristics almost similar to those of the HIP material are obtained. In addition, in Ni-base and Co-base alloys other than iron-base alloys, the wear resistance and strength are greatly improved. Incidentally, densification progressed in the sample that was vacuum-sintered only without using the glass entire surface coating method, metal foil + depressurization method, metal foil + glass sealing method, and the relative density of the sintered body was 90%. The wear depth was 100% or more.
Further, in the sample group within the scope of the present invention, the occurrence of surface cracks after the wear test was less than that of the cast material, and almost the same as that of the HIP material. Also, the seizure phenomenon was slight compared with the cast material.
The wear depth was shown as a relative ratio in the wear test in the same manner as in Table 1, assuming that the wear depth of the cast high-speed steel was 100%.

<Example 5>
Other metals include Hastelloy S (main component: 16% Cr-15% Mo-residual Ni), a Ni-based superalloy, and Stellite 6 (main component: 30% Cr-3% Ni-4.5), a Co-based superalloy. % W-1.5% Mo-residual Co) powder was preformed by a CIP apparatus at a molding pressure of 500 MPa, placed in a metal foil made of steel having a thickness of 100 μm, and sealed. In addition, three through holes of about 0.5 mmφ were made in the metal foil. A glass powder layer was formed in the through hole, which was put in a furnace and heated to 1050 ° C. under reduced pressure. After reaching 1050 ° C., the atmosphere was switched to a gas pressure atmosphere of 4 MPa and held for 3 hours. When the sample was taken out after cooling in the furnace, the hole in the metal foil was completely sealed with the glass layer solidified after melting, and the sintered metal part from which the glass layer was removed was completely densified. A plate-shaped wear test piece (20 mm × 10 mm × 30 mm) and a bending test piece (3 mm × 4 mm × 38 mm) were prepared by cutting from this sintered material, and a hot wear test and a strength test were performed. In the abrasion test, the disc-shaped heating piece was pressed against a plate-like abrasion test piece while heating the plate-like heating piece to 850 ° C. while applying a load, and the wear depth after 5000 rotations was evaluated. The strength of the sintered metal part was evaluated by a four-point bending test. The results are shown in Table 5.
The wear depth was shown as a relative ratio in the wear test in the same manner as in Table 1, assuming that the wear depth of the cast high-speed steel was 100%. Similarly, the bending strength is shown as a relative ratio when the bending strength of the cast material is 100%.

<Example 6>
Further, as other metals, pure Ti and Ti alloy (main component: Ti-6% Al-4% V) powder is pre-formed by a CIP device at a forming pressure of 700 MPa, and placed in a stainless steel metal foil having a thickness of 150 μm. I put it in and sealed it. In addition, three through holes of about 0.5 mmφ were made in the metal foil. A glass powder layer was formed in the through hole, and this was put in a furnace and heated to 1250 ° C. under reduced pressure. After reaching 1250 ° C., the atmosphere was switched to a gas pressure atmosphere of 2 MPa and held for 3 hours. When the sample was taken out after cooling in the furnace, the hole in the metal foil was completely sealed with the glass layer solidified after melting, and the sintered metal part from which the glass layer was removed was completely densified. A plate-shaped wear test piece (20 mm × 10 mm × 30 mm) and a bending test piece (3 mm × 4 mm × 38 mm) were prepared by cutting from this sintered material, and a hot wear test and a strength test were performed. In the abrasion test, the disc-shaped heating piece was pressed against a plate-like abrasion test piece while heating the plate-like heating piece to 850 ° C. while applying a load, and the wear depth after 5000 rotations was evaluated. The strength of the sintered metal part was evaluated by a four-point bending test. The results are also shown in Table 5.
As is clear from Table 5, in the range sample of the present invention, the relative density of the sintered body was also densified to 99% or more, and the wear depth rate by the wear test was greatly improved compared to the cast high speed material, It can be seen that characteristics almost similar to those of the HIP material are obtained. In addition, in Ni-base and Co-base alloys other than iron-base alloys, the wear resistance and strength are greatly improved. Incidentally, densification progressed in the sample that was vacuum-sintered only without using the glass entire surface coating method, metal foil + depressurization method, metal foil + glass sealing method, and the relative density of the sintered body was 90%. The wear depth was 100% or more.
Further, in the sample group within the scope of the present invention, the occurrence of surface cracks after the wear test was less than that of the cast material, and almost the same as that of the HIP material. Also, the seizure phenomenon was slight compared with the cast material.

<Example 7>
In addition, as other metals, Al alloy (main component: Al-2% Cu-2% Mg-6% Zn) and Mg-based alloy (main component: Mg-2% Al-1% Zn) powder can be used with a press machine. Pre-molding was performed at a molding pressure of 300 MPa, and this was put into a capsule-like thin metal foil container made of plain steel having a thickness of 100 μm. This container was provided with an exhaust steel pipe. After sealing the container, it was placed in a furnace. The exhaust pipe was taken out from the inside of the furnace, and an exhaust vacuum pump was connected to the exhaust pipe, and the temperature was raised to a predetermined 450 ° C. while reducing the pressure. When the temperature reached 450 ° C., sintering was attempted for 2 hours under two conditions of atmospheric pressure and gas pressurization (3 MPa). After the furnace cooling, the obtained sintered body was densified. A plate-shaped wear test piece (20 mm × 10 mm × 30 mm) and a bending test piece (3 mm × 4 mm × 38 mm) were produced by cutting from this sintered material, and a wear test and a strength test were performed. In the abrasion test, a disk-shaped mating piece (regular steel) was pressed against a plate-shaped abrasion test piece at normal temperature while applying a load, and the abrasion depth after 5000 rotations was evaluated. The strength of the sintered metal part was evaluated by a four-point bending test.
As is clear from Table 6, in the range sample of the present invention, the relative density of the sintered body was also densified to 99% or more, and the wear depth rate by the wear test was greatly improved compared to the cast high speed material, It can be seen that characteristics almost similar to those of the HIP material are obtained. In addition, in Ni-base and Co-base alloys other than iron-base alloys, the wear resistance and strength are greatly improved. Incidentally, the densification did not progress in the sample subjected to only vacuum sintering without using the glass entire surface coating method, the metal foil + depressurization method, and the metal foil + glass sealing method, and the relative density of the sintered body was 90%. The wear depth was 100% or more.
Further, in the sample group within the scope of the present invention, the occurrence of surface cracks after the wear test was less than that of the cast material, and almost the same as that of the HIP material. Also, the seizure phenomenon was slight compared with the cast material.
The wear depth was shown as a relative ratio in the wear test in the same manner as in Table 1, assuming that the wear depth of the cast high-speed steel was 100%. Similarly, the bending strength is shown as a relative ratio when the bending strength of the cast material is 100%.

The figure which shows the relationship between the Vickers hardness and sintering retention temperature in LIP method sintering of this invention. It is a SEM image of the sintered compact obtained by the LIP method of this invention, (a) is the structure of what was sintered at 1423K with the rotary pump, (b) is the structure photograph which shows the structure of what was sintered at 1473K with the diffusion pump It is. The figure which shows the relationship between the porosity of a sintered compact, and Vickers hardness. It is sectional drawing which shows the sintering method at the time of wrapping a preforming body with capsule-shaped metal foil, and attaching the pressure reduction pipe | tube. It is sectional drawing which wraps a preforming body with the capsule-shaped metal foil with a hole, and shows the sintering method which puts glass powder or a glass plate in a hole part. It is sectional drawing which shows the sintering method at the time of coat | covering the glass powder layer on the whole surface of a preforming body.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sintering furnace 2 Pre-formed object 3 Glass powder layer 4 Pressure reducing device and gas pressure device 5 Metal foil 6 Pressure reducing device 7 Metal tube for pressure reduction 8 Glass powder layer or glass plate 9 Through-hole

Claims (11)

  When the metal and alloy are manufactured by sintering, the metal and alloy powder are preformed, and then the preform is wrapped in a metal foil capsule with an exhaust pipe, and placed in a furnace. A method for producing a sintered metal and alloy, characterized in that the inside of the furnace is heated to a predetermined sintering temperature at atmospheric pressure while being reduced in pressure from outside the furnace through an exhaust pipe to 0.08 MPa or less.   2. The method for producing a metal and alloy sintered body according to claim 1, wherein after raising the temperature to the sintering temperature, the inside of the furnace is brought into a pressurized state of a pressure of 0.08 to 5 MPa.   When the metal and alloy are manufactured by sintering, the metal and alloy powder is preformed, and then the preform is wrapped in a metal foil capsule having one or more holes, and the holes are made of glass powder or glass. Covering with a plate, raising the temperature to a predetermined sintering temperature under a reduced pressure of 0.08 MPa or less to bring the glass into a molten state, and then sintering under a low pressure of 0.08 to 5 MPa. A method for producing a sintered metal and alloy.   The method for producing a metal and alloy sintered body according to any one of claims 1 to 3, wherein the metal foil of the capsule has a thickness of 5 to 300 µm.   When the temperature is raised to a predetermined sintering temperature under reduced pressure, the temperature is once raised to a temperature 25 to 100 ° C. higher than the predetermined sintering temperature, and sintering is performed at the predetermined sintering temperature. Item 5. The method for producing a sintered metal and alloy according to any one of Items 1 to 4.   When the metal and alloy are produced by sintering, the metal and alloy powder is preformed, and then the preform is coated with glass powder and heated to a predetermined temperature under a reduced pressure of 0.08 MPa or less. A method for producing a sintered metal and alloy, characterized in that the glass powder is melted and then sintered under a low pressure of 0.08 to 5 MPa.   The method for producing a metal and alloy sintered body according to any one of claims 1 to 6, wherein a molding pressure at the time of the preforming is 50 to 1000 MPa. 8. The softening point of the glass is 600 ° C. to 1000 ° C., and the melt viscosity at 1100 ° C. of the glass is 10 ² to 10 ⁵ Pa · s. Manufacturing method of metal and alloy sintered compact.   The metal and alloy sintered body is an iron-based alloy, nickel, nickel-based alloy, cobalt, or cobalt-based alloy, and the predetermined sintering temperature is 900 to 1250 ° C. The manufacturing method of the metal and alloy sintered compact of any one of these.   The metal and alloy sintered body according to any one of claims 1 to 8, wherein the metal and alloy sintered body is titanium or a titanium-based alloy, and the predetermined sintering temperature is 1000 to 1350 ° C. A method for producing an alloy sintered body.   The metal according to claim 1 or 2, wherein the metal and alloy sintered body is aluminum, an aluminum-based alloy, magnesium, or a magnesium-based alloy, and the predetermined sintering temperature is 250 to 550 ° C. And a method for producing an alloy sintered body.