KR900004597B1 - Material sheet for metal sintered body and method for manufacturing the same and method for manufacturing metal sintered body - Google Patents

Abstract

The method comprises (i) mixing 70-90 wt.% of self-fluxing alloy powder and 10-30 wt.% of metal powder of high melting point, which is higher than self-fluxing alloy powder and to which seflfluxing alloy powder can adhere to form mixture having a sintering property; (ii) kneading 1-10 wt.% of plastic binder with mixture obtained to form moulded body of predetermined shape; and (iii) sintering at a temperature above the liquid phase line of selffluxing alloy powder.

Description

Raw material sheet for metal sintered body and its manufacturing method and method for manufacturing metal sintered body

1 to 3 show a first embodiment of the present invention, and FIG. 1 is a cross-sectional view of a press die.

2 is an explanatory diagram of a manufacturing process of a press die.

3 is a graph showing the relationship between temperature and time in the sintering process chart.

4 is an explanatory view showing the sintering treatment of three molded bodies in the second embodiment of the present invention.

5 is an explanatory view of a manufacturing process of a press die in a third embodiment of the present invention.

6 is an enlarged view based on a micrograph (400 times) of a metal sintered body.

7 is a graph showing the relationship between the sintering temperature and the dimensional change.

* Explanation of symbols for main parts of the drawings

1: mold 2: base material

3: workpiece processing part 4: raw material sheet

2a: base surface 3a: molded body

6: alumina sheet 12, 13: backup body

S ₁ , S ₂ , S ₃ , S ₄ ,: Sintered body

The present invention relates to a raw material sheet for a metal sintered body, a method for producing the same, and a method for producing a metal sintered body. In the case of manufacturing a metal sintered body in the past, in order to facilitate the molding operation, a plastic material mixed with a sinterable metal powder and a synthetic resin binder is used, and then molded into a certain shape, and then the synthetic resin in the molded body. It has already been proposed to thermally decompose the binder and to sinter the metal powder.

In the above method, if no back-up means is taken when sintering the metal powder, the sintered body expands and causes a change in dimensions, and thus there is a concern that a variation of approximately 4% may occur before and after sintering.

As a sinterable metal powder, a self-soluble alloy powder, for example, Ni-B-Si-based Ni-soluble alloy powder, is used, but the solid-state wire of the alloy is 1010-1020 ° C. , The liquidus line is 1075-1085 ℃, and the sintering strength is better when sintering in the lower temperature range than the solidus line, but the sintering strength is weakened, and when sintering in the high temperature range beyond the liquidus line, all powders dissolve and flow. Shape retention deteriorated.

Thus, sintering was performed at a suitable temperature between the solidus and the liquidus, for example, around 1050 캜. However, when sintered at the above-mentioned temperature, the sintered body showed dimensional change by shrinkage, so that the precision of the dimensional was not good and the sintering strength was not so high.

Furthermore, although the above-mentioned plastic material was formed in the sheet form, the raw material sheet was formed, and the metal sintered body was obtained using the raw material sheet, but in this case, depending on the material of the synthetic resin binder, the lamination of the raw material sheet )), The interlayer peeling (層 間 剝 里) occurs in the molded body, and there was a problem of cracking and bursting.

In view of the above, it is an object of the present invention to provide a manufacturing method in which dimensional precision is good and a high strength metal sintered body can be obtained.

Another object of the present invention is to provide a production method as described above, which can suppress expansion of the metal sintered body by simple means.

Furthermore, an object of this invention is to provide the raw material sheet which is excellent in lamination property, does not generate | occur | produce interlayer peeling, and is excellent also in crack resistance.

In order to achieve the above object, according to the present invention, 70-90% by weight of a soluble alloy powder, and 10-30% by weight of a high melting point metal powder having a higher melting point than that of the soluble alloy powder and easy to melt. Mixing to obtain a sinterable metal powder, a mixture of 1 to 10% by weight of a synthetic resin binder mixed with the sinterable metal powder to obtain a shaped body having a predetermined shape, and forming the molded body into a liquid-line of the magnetic soluble alloy powder. It is possible to provide a method for producing a metal sintered body made by a step of sintering at a temperature exceeding this. According to the present invention, a sinterable metal is prepared by mixing 70-90% by weight of a soluble alloy powder and 10-30% by weight of a high melting point metal powder having a higher melting point than that of the soluble alloy powder and which is easy to melt. A process of obtaining a powder, a process of obtaining a sinterable metal powder, a process of obtaining a molded body having a constant shape by using a mixture of 10-10% by weight of a synthetic resin binder mixed with the sintered metal powder, and the surface of the molded body Provided is a method for producing a metal sintered body formed by a step of sintering at a temperature above the liquidus line of a magnetically soluble alloy powder in a state covered with a back up. Furthermore, according to the present invention, a process of forming a molded body by molding a plastic material mixed with a sinterable metal powder and a synthetic resin binder into a predetermined shape, a step of wrapping the molded body with a granular backup body, and thermally decomposing the synthetic resin binder in the molded body A method for producing a metal sintered body comprising a step of sintering a powder is provided.

According to the present invention, there is provided a raw material sheet for metal sintered body composed of a sinterable metal powder, a thermoplastic resin having excellent crack resistance, and a synthetic resin binder containing a thermoplastic synthetic resin having excellent lamination.

As described above, since the specific melting amount of the high melting point metal powder is mixed with the high melting point metal powder as described above, the flow of the high melting point metal powder is high even when the magnetic alloy powder is sintered at a temperature above the liquidus line. The metal sintered body which is hindered by this and has excellent shape retention and dimensional accuracy can be obtained. In addition, it is possible to obtain a high-strength metal sintered body because of good bonding between the magnetically soluble alloys and the entanglement and adhesion of the magnetically soluble alloys and the high melting point metal powder.

In addition, by mixing the above-mentioned specific amount of the synthetic resin binder in a mixed powder of a self-soluble alloy powder and a high melting point metal powder, a molded article having good shape retention can be obtained even when the molding pressure is low, and it is integrally bonded to the base metal. In the case of obtaining a metal sintered body, it is possible to easily carry out the work of spreading and pasting the base metal of the mixed powder and forming the mixed powder.

Furthermore, since the molded product obtained from the mixed powder of the self-soluble alloy powder and the high melting point metal powder is sintered while the surface is covered with the backup body, the dimensional sintering of the metal sintered body can be suppressed according to the backup body to improve the dimensional accuracy. can do.

Furthermore, according to the extremely simple means of enclosing a molded body made of a plastic material with a granular backup body, it is possible to suppress the dimensional change of the metal sintered body due to expansion and obtain a metal sintered body with high dimensional accuracy.

In addition, since the synthetic resin binder of the raw material sheet contains thermoplastic synthetic resin having excellent cracking resistance and thermoplastic synthetic resin having excellent lamination, the strength of the interlayer adhesion is high without the occurrence of delamination or cracking in the molded product obtained from the raw material sheet. In addition, a good molded article having a surface property can be obtained, and a metal sintered body having excellent dimensional accuracy and surface property can be obtained.

In addition, in preparing the raw material, a sinterable metal powder and a liquid synthetic resin binder having a specific material as described above are mixed to obtain a plastic material, and then a small amount of the synthetic resin binder is uniformly applied to the sinterable metal powder by heating and drying the plastic material. can do. Thus, by uniformly applying the synthetic resin binder to the sinterable metal powder, a sheet having good shape retention can be obtained in the sheet forming operation in the next step, and a high-strength metal sintered body having a small porosity can be obtained by using a small amount of the synthetic resin binder. Will be.

The plastic material can be molded into a sheet in a thermoplastic state, which facilitates the molding work, and is an easy-to-handle raw material having moderate flexibility and tear strength at room temperature. A sheet can be obtained.

Other objects, features and advantages described above in the present invention will become apparent from the following description of the most suitable embodiment according to the accompanying drawings.

Among the sinterable metal powders used in the present invention, as the magnetic alloy powders, magnetic alloy powders such as Ni-based, Co-based, Fe-based, etc. correspond. Also, in order to improve the strength of the metal sintered body by setting the sintering temperature of the self-soluble alloy powder beyond the liquidus line of the alloy, as the sinterable metal powder, the melting point is higher than that of the self-soluble alloy powder, and the self-soluble alloy powder is easy to weld. A high melting point metal powder is added to the magnetically soluble alloy powder, and the high melting point metal powder prevents the flow of the soluble alloy to improve shape retention. , WC, Fe-Mo (ferro-molybdenum), any one of powders or a mixture thereof can be used.

Examples of the thermoplastic synthetic resin having excellent crack resistance in the raw material sheet include ethylene tetrafluoride resin, polystyrene resin, nylon, and the like, and acrylic resin, polyethylene resin, butadiene vinyl acetate copolymer, and the like which have excellent lamination properties.

Example 1

(Production of raw sheet)

80 weight% of Ni-soluble alloy powder of 10-60 micrometers in diameter, and 20 weight% of Mo-pulverized powder of 10-53 micrometers in diameter are mixed with a V-blender for 30 minutes, and a mixed powder is obtained. Ethylene tetrafluoroethylene emulsion and acrylic resin emulsion are mixed at a ratio of 1: 1 to obtain a liquid synthetic resin binder.

To the mixed powder is added, the third weight% of the synthetic resin binder is mixed at room temperature for 5 minutes in a table top kneading device to obtain a plastic product. In this case, since the synthetic resin binder is an emulsion type, the dispersibility is good, and a small amount of the synthetic resin binder can be uniformly dispersed in the mixed powder in a short mixing period.

In the drying furnace, the plasticizer is heated to 80-120 ° C. using a heater such as a heater to evaporate the moisture in the synthetic resin binder to dry the plasticizer. The properties of the obtained plastic product are tenaciously bound by a synthetic resin binder to form a myriad of lumps, and the mixed powder is uniformly coated by the synthetic resin binder.

After drying, the plastics, which had a heat of approximately 80 ° C. and were in a thermoplastic state, were placed in a roll equipped with a roll having a diameter of 245 mm and a length of 215 mm. Three kinds of raw material sheets are molded. It is 0.5 kg / mm <2> in density conversion with the test piece press-formed by molding pressure. In this case, when the roll of the roll group is heated to the same temperature as the plastic material (approximately 80 ° C.), the forming operation of the raw material sheet can be improved.

After molding, the raw material sheet is heated at 80 ° C. for 30 minutes to remove the shape change caused during molding.

The obtained raw material sheet has moderate flexibility and tear strength at room temperature.

The amount of the synthetic resin binder added to the mixed powder is preferably 1-10% by weight. When the amount of the synthetic resin binder added is less than 1% by weight, sheet formation cannot be performed. On the other hand, when the amount is more than 10% by weight, the processing rate of the metal sintered body becomes high and a high strength metal sintered body cannot be obtained.

Moreover, the compounding quantity of the thermoplastic synthetic resin which is excellent in lamination property with respect to the thermoplastic synthetic resin which is excellent in crack resistance in a synthetic resin binder is 30-70 weight%. If the compounding quantity of the thermoplastic synthetic resin excellent in lamination property exceeds 70 weight% of 30 weight%, the surface will be cracked at the time of shaping | molding.

Example 2

(Manufacture of die for press using the raw material sheet mentioned above)

FIG. 1 shows a press die 1 for molding a tank, which is melted on a base 2 and a base casted from cast steel (JIS SC46 ash). The workpiece | work processing part 3 which consists of metal sintered compacts, etc. is comprised.

As shown in FIG. 2 (a), the base surface 2a of the base material 2 is 5-20 mm from the outer surface (shown by the broken line) outside the workpiece processing part 3 in the completed mold 1. It is molded to be low. The base material 2 can be cast as it is cast, and the base surface 2a having the black leather is sandblasted, cleaned, and then coated with acrylic resin adhesive.

As shown in Fig. 2 (b), three raw material sheets 4 having a thickness of 3 mm are laid on the base surface 2a and overlapped, and the raw material sheets 4 are formed in accordance with the synthetic resin female type M installed in a press. It presses and examines the contact state with respect to the raw material sheet of female-type M, and cuts off the raw material sheet 4 in the part which touches a lot, and spreads and attaches the new raw material sheet 4 to the part which does not touch. The pressurization of the female mold M and the cutting and spreading of the raw sheet 4 are repeated to roughly match the shape of the red filler raw material sheet 4 to the shape of the female mold M. The laminated raw material sheet 4 which has undergone such a molding step has a high strength of interlayer contact, cracks, and no cracking and good surface appearance. In this case, the pressing force of the female type M is 0.2-0.3 kg / mm <2>.

As shown in Fig. 2 (c), the base material 2 is installed in the heating furnace 5 together with the stacked raw material sheets 4, and the laminated raw material sheets 4 are heated at 80 DEG C and plasticized.

As shown in FIG. 2 (d), the laminated raw material sheet 4 obtained by laminating and spreading the raw material sheet 4 having a gold thickness of 3 mm on the plasticized laminated raw material sheet 4 again is described above. According to the female mold M, the molded body 3a having the same shape as the workpiece processing part 3 is formed by pressing with a pressing force of 0.7 kg / mm 2.

In this case, talc powder is applied to female M to improve mold release from the molded body 3a of female M. Alternatively, a thin film body such as polyvinylidene chloride resin, polyvinyl chloride resin, or polyethylene resin is provided between the female type M and the laminated raw material sheet 4.

After the molding operation is completed, when the temperatures of the base material 2 and the formed body 3a are cooled to room temperature, excess portions are removed from the formed body 3a.

As shown in Fig. 2 (e), the alumina sheet 6 having a thickness of 1 mm is laminated on the molded body 3a, and the base material 2 is installed in the container 7, and as a backup body in the container 7, A steel ball 8 having a diameter of 0.75 mm is flowed in. The alumina sheet 6 was composed of an alumina powder and a synthetic resin binder as described above, and prevented the transfer of the roughened surface of the uneven surface by the myriad steel balls 8 to the molded body 3a, thereby sintering the metal sintered body. It is to suppress the dimensional change of the sintered metal s, i.

Subsequently, the base material 2 is installed in the vacuum sintering furnace 9 to decompose the organic material and sinter the Ni-soluble alloy and powder under the heat-cooling conditions shown in FIG. Carrier gas uses nitrogen gas or hydrogen gas with a strong perfection.

(A) First heating zone (Figure 3 A)

This heating zone A is from room temperature to 650 ° C., and the temperature increase rate is 10-20 ° C./min. In this heating zone A, water first evaporates, and then tetrafluoroethylene resin and acrylic resin in the synthetic resin binder in the molded body 3a and the alumina sheet 6 decompose and gasify. These resins are gasified at 30-400 ° C., but heat is maintained at 600-650 ° C. for 90 minutes in consideration of thermal conductivity to remove almost all organic materials and leave Ni-soluble alloy-Mo powder. When the gasification of this organic substance is explained according to the change of the degree of vacuum in the vacuum sintering furnace 9, although it is 1 Torr at normal temperature, when it heats uniformly at 650 degreeC for 90 minutes, the vacuum degree will fall to 2 Torr at the maximum. This is mainly because decomposition gas of organic substance is produced. After 90 minutes, the vacuum degree again rises to 1 Torr, which means that the decomposition gas was removed in the vacuum sintering furnace 9.

(B) Second heating zone (Figure 3 B)

This heating zone B is in the range of 900-1000 ° C., and the Ni magnetic alloy-Mo powder is heated uniformly for 30 minutes at a temperature below the solidus line (1010-1020 ° C.) of the Ni magnetic alloy, for example, 950 ° C. The solid state sintering treatment is carried out, and it is sintered. The rate of temperature increase from the first heating zone A is 10-20 ° C./minute.

Since the Ni-soluble alloy-Mo powder in the vacuum sintering furnace 9 is heated from the surface thereof and heated up, a constant heating time is required until the whole powder reaches a uniform temperature. If the sintering temperature of 1000-1200 ℃ is suddenly heated, a temperature difference is generated between the surface portion of the Ni-soluble alloy-Mo powder and the portion in contact with the base surface 2a, resulting in a large variation in porosity and obtaining a uniform metal sintered body. In addition, defects such as cracks after sintering are likely to occur.

In the second heating zone B, undecomposed organic matter is completely removed by gasification. By the gasification or the like, the vacuum degree in the vacuum sintering furnace 9 temporarily drops to 4 Torr, but returns to 1 Torr after 30 minutes.

(C) Third heating zone (Figure 3 C)

This heating zone C is the solid phase (1010-1020 ° C) of the Ni-soluble alloy, and is just below the liquid line (1075-1085 ° C), that is, in the range of 1000-2000 ° C. For example, the temperature beyond the liquid line is maintained at a constant temperature for 1100-1180 ° C, preferably 1160 ° C for 120 minutes to perform liquid phase sintering in accordance with the dissolution of Ni-soluble alloy to form a metal sintered body s. In this case, the flow of the Ni-soluble alloy is hindered by the presence of Mo, so the shape retention is good. The temperature increase rate from the second heating zone B is 15-20 ° C./minute, and since the Ni-soluble alloy-Mo sintered body is already heated to a high temperature in the second heating zone B, the temperature raising time to the third heating zone C is small. . If the holding time of the third heating zone is insufficient, the sintering may not be performed completely, resulting in a defect in the metal sintered body s.

The reason for selecting the sintering temperature as 1160 ° C is that when the sintering temperature is about 1200 ° C, the dimensional change of the sintered body s becomes large, and the sintering furnace temperature control is not easy, and the temperature in the sintering furnace is unbalanced. It is because 1160 degreeC is suitable as a working temperature for removing such a defect.

(D) Cooling zone (Figure 3 D)

This cooling zone D are tertiary cooling zone in said one bar sintering temperature to a second cooling zone D ₂ and, 400 ℃ approximately up to about 400 ℃ in the primary cooling zone D _1, and approximately 800 ℃ up to about 800 ℃ Can be divided into D ₃ .

The primary cooling zone D ₁ is a stable range under the high temperature of the metal sintered body S. In this cooling zone D ₁ , cooling is performed at a slow speed of up to 2 ° C./min in consideration of the cooling efficiency as much as possible. In this cooling zone D ₁ , the rapid quenching causes a lot of cracks in the metal sintered body s. In the secondary cooling zone D ₂ , cooling is performed at a slow rate of up to 3 ° C./min in order to absorb the linear expansion of the base material 2 and the dimensional change in the Ar ₁ transformation. In this case, the bow shaft of the metal sintered body s is 14.6 × 10 ⁻⁶ / ° C., but it follows the shrinkage of the base material 2 because it is porous. When rapid cooling proceeds in this cooling zone D ₂ , many cracks occur in the metal sintered body s.

In the tertiary cooling zone D ₃ , the temperatures of the metal sintered body s and the base material 2 are cooled to room temperature by gas cooling (including air cooling) other than liquid cooling such as water and oil.

As shown in FIG. 1 through the above-mentioned heat-cooling process, the metal mold | die 1 formed by the metal sintered compact s which forms the workpiece processing part 3 according to Ni-soluble alloy-Mo can be obtained.

Said metal sintered compact S has favorable weldability with the base material 2, and defects, such as a crack, do not generate | occur | produce. In addition, when the shape of the mold 1 is 300 mm long, 250 mm wide and 180 mm high, the shape is measured in the X and Y directions by 50 mm intervals according to the three-dimensional measuring machine. There were three locations where only mm was expanded, and other locations showed 0-0.3 mm of expansion, and the dimensional accuracy was found to be excellent. In addition, the use of the alumina sheet 6 can prevent the roughened surface of the steel ball 8 from being transferred to the molded laminated body 3a, so that the metal sintered S surface roughness is good.

Therefore, the metal mold | die 1 obtained through the above process can be used for press work immediately by performing a simple finishing process.

Said alumina sheet 6 can be manufactured through the process demonstrated next.

To the alumina powder having a diameter of 2-50 µm, 8% by weight of the same synthetic resin binder as that used for the production of the raw material sheet was added, mixed at room temperature for 5 minutes using a table kneader, and 3% by weight of water was added to the mixture. The resulting plastic was heated with a heater at 120 ° C. for 60 minutes, and the water in the synthetic resin binder was evaporated to dry the plastic.

After drying, the alumina sheet 6 having a thickness of 1 mm is formed by using the same method as that used for preparing the raw material sheet by using a thermoplastic material in which the thermoplastic material in a thermoplastic state is suspended by floating at about 80 ° C. . In this case, the sheet forming operation can be easily performed by heating the roll of the roller to the same temperature as the plastic material (approximately 80 ° C). After molding, the alumina sheet 6 is heat treated at 80 ° C. for 30 minutes to remove the change in shape generated during molding.

Example 3

(Manufacture of sliding member using raw material sheet)

After degreasing the cold rolled steel sheets 100 mm long and 1.5 mm thick, and then laminating the two sheets of the above-described raw material having a thickness of 3 mm with an acrylic resin adhesive and laminating them together, the surface of the raw material sheet is laminated. The smooth finish is obtained to obtain a plate-shaped molded product.

The obtained molded product is placed in vacuum sintering to decompose organic matter and sinter Ni powder and Ni powder in the same heat-cooling conditions as in FIG. Furthermore, the sintering time is 30 minutes.

The sliding member has a good surface roughness of the sliding surface of the metal sintered body, has excellent sliding performance, and the metal sintered body is reliably welded to the steel sheet so that no interlayer peeling occurs.

In this case, in order to improve the lubricity of the metal sintered compact, the sintered compact is immersed in a lubricating synthetic resin such as tetrafluoroethylene resin and cured. Or it may leave a mixture of solid lubricant, such as WS _2, MOS ₂ in the raw material sheet.

In order to increase the thickness of the metal sintered body of the sliding member, a raw material sheet having a thickness of 3 mm is spread on the sintered body with an acrylic resin adhesive, and then the surface is smoothly finished, followed by sintering in the same manner as described above. A sliding member having a metal sintered body of a layer structure is obtained.

In this sliding member, both metals are reliably welded, and no interlayer peeling occurs during use.

Example 4

(Method for Producing Sintered Body Using Raw Material Sheet)

The cylindrical shaped bodies 10 _{1-10 3} having a diameter of 20 mm and a length of 20 mm are formed at a pressure of 1 kg / mm 2 applied using the above-described raw material sheet, and these are sintered.

In the sintering process, in the case of the molded article 10 ₁ , as shown in FIG. 4 (a ₁ ), the molded article 10 ₁ is placed in the container 11, and the molded article 10 ₁ is 0.5-1 mm in diameter as a granular backup body and linear expansion The container 11 is squeezed with 11 × 10 ⁻⁶ / ° C. steel balls 12 ₁ and installed in the vacuum sintering furnace 9.

In the case of the molded article 10 ₂ , as shown in FIG. 4 (a ₁ ), the molded article 10 ₂ is placed in a container 11 and the molded article 10 ₂ is placed in a line No. 5 silica sand having a linear expansion of 4 × 10 ⁻⁶ / ° C. ( 13) and the container 11 is installed in a vacuum sintering furnace 9.

In the case of the molded body F ₃ , it is installed in the vacuum sintering furnace 9 without a backup body as shown in FIG. 4 (a ₃ ). The organic material is decomposed and the metal powder is sintered under the heat-cooling conditions shown in FIG. In this case, since the steel balls 12 and the silica sand 13 as the back-up bodies in Figs. 4 (a ₁ ) and (a ₂ ) are granular particles, the product gas produced by the decomposition of the synthetic resin is separated from the steel balls 12 and the silica sand (13). ) It is scattered in the backup body through numerous continuous pores. Moreover, preferable sintering temperature is 1120 degreeC.

The elongation rate was measured with respect to the length before and behind the sintering process in the three sintered compacts obtained through the above process, The result of Table 1 was obtained. The sintered compacts S _1- (S ₂ ) in the case correspond to the molded bodies 10 _{1-10 3} , respectively.

TABLE 1

When sintering the shaped bodies 10 _{1-10 3} as evident in Table 1 above, the sintered bodies S _1- (S ₂ ) obtained by using the backing bodies 12, 13 are sintered when sintered. Since the expansion is suppressed by the force of the companies 12 and 13, the elongation is significantly attenuated compared with the sintered body S ₃ obtained without using the backup body.

Example 5

(Manufacture of die for press using raw material sheet)

As shown in FIG. 5 (a), the base material 2 for tanks is cast from cast steel (JIS SC46 material) similar to Example 2. FIG. The base material 2 can be used as it is cast, and the base surface 2a having the hump is thoroughly cleaned and then an acrylic resin adhesive is applied.

As shown in Fig. 5 (b), the raw material sheet 4 is laid on the foundation surface 2a, laid out and pasted, which is pressurized using a female mold with a pressure of 0.5 kg / mm &lt; 2 &gt; Molded body 3a (figure (c)) is molded.

As shown in FIG. 5 (c), the base material 2 is placed in the container 7, the molded body 3a is wrapped in steel balls 12 as a backup body, and the container 7 is installed in the vacuum sintering furnace 9. Thus, the mold 1 having the workpiece processing part 3 composed of the Ni-soluble alloy-Mo sintered body S ₄ and the decomposition of the organic substance in the molded body 3a under the heat-cooling conditions of FIG. 3 can be obtained.

The elongation in the thickness direction before and after the sintering of each part (x)-(y) in the workpiece processing part 3 of the die 1 described above was measured by using a three-dimensional measuring instrument. , 0.5 mm in the region (y) and 0.1 mm in the region (z), it was clear that the dimensional change of the metal sintered body (S ₄ ) was significantly suppressed by the backup body 12.

Furthermore, as a backing body, spherical alumina, spherical ceramics, etc. may be used in addition to the steel balls and silica sand, and if necessary, the steel balls may be partially bonded with an inorganic binder such as water glass, and the distributor may be used as the shape of the molded body. In this case, the raw material sheet 4 may be semi-hardened to be ground.

Example 6

60 weight% of the Ni-soluble alloy powder having a diameter of 10-60 m is mixed to obtain a mixed powder. Synthetic resin binder in which 1: 1 mixture of ethylene tetrafluoroethylene emulsion and acrylic resin emulsion is adjusted, 1.5 wt% of the synthetic resin binder is added to the mixed powder, and the mixture is thoroughly mixed to obtain a plastic product. This plastic product is put into a mold and molded with a pressing force of 0.5 kg / mm 2 to obtain a cylindrical molded body having a diameter of 20 mm and a length of 20 mm.

The molded body is placed in a vacuum sintering furnace to decompose organic matter and sinter metal powder under the heat-cooling conditions shown in FIG. In this case, the sintering temperature is 1120 DEG C, which is the temperature beyond the liquidus line of the Ni-soluble alloy powder, and the sintering treatment time is 20 minutes.

Thereby, the metal sintered body is obtained from the above-mentioned shaped body. As Comparative Example 1, the cylindrical compacts having the same dimensions as above were formed by using 91 wt% of the Ni-soluble alloy powder and 9 wt% of the Mo powder to obtain metal sintered bodies under the same sintering conditions as described above. In Comparative Example 2, a cylindrical molded body having the same dimensions as above was formed by using a mixed powder composed of 69% by weight of Ni-soluble alloy powder and 31% by weight of Mo powder and a synthetic resin binder, and the same sintering conditions as described above. To obtain a metal sintered body.

The shape retention, dimensional change, and sintering strength of each metal sintered body were investigated. The results shown in Table 2 were obtained.

TABLE 2

As apparent from Table 2, the metal sintered body obtained by the present invention showed only a slight expansion amount, and the dimensional accuracy and shape retention were good.

FIG. 6 shows the degree of magnification based on the optical micrograph (400 times) of the metal sintered body obtained by the present invention, in which m is Mo and n is Ni-soluble alloy.

In Fig. 6, it is clear that the binding between the Ni-soluble alloys and the interlocking and welding properties of the Mo and Ni-soluble alloys are good. Therefore, the strength of the metal sintered body is high and, for example, the compressive strength of 4 kg / mm2 You can get it.

Furthermore, in order to improve the compressive strength of the metal sintered body, the compressive strength of 7 kg / mm <2> can be ensured by performing this process by hardening by vacuum-permeating synthetic resin, such as an epoxy resin, in the process part of the sintered compact. When more than this compressive strength is required, it is better to infiltration the metal sintered body by using low melting point metal such as Cu.

Example 7

According to the same method as in Example 6, a molded article having the same composition, same shape and dimensions, that is, a diameter containing 80% by weight of Ni-soluble alloy, 20% by weight of Mo powder and 1.5% by weight of synthetic resin binder with respect to the mixed powder thereof Several 20 mm and 20 mm long cylindrical molded bodies are obtained.

On the surface of some of these shaped bodies, a refractory cell having fine continuous pores is formed as a backing body. This cell is formed by subjecting the adhesive film obtained by adding a molded body to a slurry of high viscosity obtained by adding an alumina powder as an inorganic binder to a water suspension of zirconia silicate as a refractory material after low drying and heating at 100 ° C. for 1 hour.

Further, for comparison, a molded article having the same shape and dimensions containing only Ni-soluble alloy powder as the metal powder is obtained.

7 shows the sintering temperature and the dimensional change of the metal sintered body when the above-mentioned molded body is sintered. Line (a _1), in the case of a metal sintered body having no cell consisting of Ni-party soluble alloy with Mo, line (a ₂₎ is the case of geusok sintered body having a cell has a composition similar to, line (b) is a Ni-party-functional alloy This is the case for all metal sinters.

In the range of sintering temperature 1100-1180 ° C indicated by oblique lines in the figure, the binding properties between Ni-soluble alloys and the interweaving and adhesion between Mo and it are good. _In the case of the metal sintered body without cell 1), it is suppressed at +1 to +3 (expansion) and in the case of the metal sintered body in which the cell of line a ₂ is provided at + 0.5% or less (expansion).

The reason why the change in the size of the metal sintered body is suppressed by providing the cell is that the metal sintered body obtainable by the present invention is in the expansion tendency, and the expansion is prevented by the backup effect of the cell.

On the other hand, in the case of the metal sintered body of the Ni-soluble alloy plate of the line b, it is apparent that when sintered at 1040 ° C., which is a temperature between a solid line and a liquid line as in the prior art, dimensional change due to shrinkage is apparent.

In the case of applying the present invention to the production of a die for pressing, the plastic material obtained in Example 6 is applied to a base such as cast iron, cast steel, alloy steel, and the like, and the plastic product is molded into a constant shape and then fired. To do.

In this case, since the plastic material is easy to handle, it can facilitate the spreading and molding operations.

Furthermore, in the above embodiment, a synthetic resin binder is added to the mixed powder of the magnetically soluble alloy powder and the high melting point metal powder, but a molded body, that is, a green compact can be obtained without adding the synthetic resin binder.

Claims (26)

A step of obtaining a sinterable metal powder by mixing 70-90% by weight of a soluble alloy powder with 10-30% by weight of a high melting point metal powder having a higher melting point than that of the soluble alloy powder and which is easy to weld. Using a mixture of 1-10% by weight of a synthetic resin binder mixed with the sinterable metal powder to obtain a molded article having a constant formation, and sintering the molded article at a temperature above the liquidus line of the above-described magnetic alloy powder. Method for producing a metal sintered body consisting of. The method for producing a metal sintered body according to claim 1, wherein the magnetic soluble alloy powder is any one of Ni magnetic soluble alloy powder, Fe magnetic soluble alloy powder, and Co magnetic soluble alloy powder. The method for producing a metal sintered body according to claim 1 or 2, wherein the high melting point metal powder is any one of Mo, W stainless steel WC, and Fe-Mo (ferro-molybdenum). The method for producing a metal sintered body according to claim 1 or 2, wherein the high melting point metal powder is a mixture of two or more selected from Mo, W stainless steel WC, and Fe-Mo (ferro-molybdenum). The method for producing a metal sintered body according to claim 1 or 2, wherein the synthetic resin binder is a mixture of a tetrafluoroemulsion emulsion and an acrylic resin emulsion. A step of obtaining a sinterable metal powder by mixing 70-90% by weight of a soluble alloy powder with 10-30% by weight of a high melting point metal powder having a higher melting point than that of the soluble alloy powder and which is easy to weld. Using a mixture of 1-10% by weight of a synthetic resin binder mixed with the sinterable metal powder to obtain a molded article having a uniform formation, and the liquid phase of the magnetically soluble alloy powder in a state in which the molded article is covered with a backup body. A method for producing a metal sintered body comprising a step of sintering at a temperature above a line. 7. The method for producing a metal sintered body according to claim 6, wherein the magnetic soluble alloy powder is any one of Ni magnetic soluble alloy powder, Fe magnetic soluble alloy powder, and Co magnetic soluble alloy powder. The method for producing a metal sintered body according to claim 6 or 7, wherein the high melting point metal powder is any one of Mo, W stainless steel WC, and Fe-Mo (ferro-molybdenum). The method for producing a metal sintered body according to claim 6 or 7, wherein the high melting point metal powder is a mixture of two or more selected from Mo, W stainless steel WC, and Fe-Mo (ferro-molybdenum). The method for producing a metal sintered body according to claim 6 or 7, wherein the synthetic resin binder is a mixture of a tetrafluoroemulsion emulsion and an acrylic resin emulsion. The method for producing a metal sintered body according to claim 6 or 7, wherein the backup body is any one of a rigid body, silica sand, spherical alumina, and spherical ceramic. The method for producing a metal sintered body according to claim 11, wherein the alumina site is interposed between the molded body and the backup body. The method for producing a metal sintered body according to claim 6 or 7, wherein the backup body is a cell made of a refractory agent. The method for producing a metal sintered body according to claim 13, wherein the backing body is formed by a slurry of high viscosity obtained by adding an alumina powder as an inorganic binder to a water suspension of zirconia silicate as a refractory material. A step of obtaining a sinterable metal powder by mixing 70-90% by weight of a soluble alloy powder with 10-30% by weight of a high melting point metal powder having a higher melting point than that of the soluble alloy powder and which is easy to weld. And a step of obtaining a molded article having a constant formation by using the sinterable metal powder, and a step of sintering the molded article at a temperature above the liquidus line of the magnetic soluble alloy powder. 70-90% by weight of the sinterable metal powder in a raw material sheet for metal sintering body composed of a sinterable metal powder, a synthetic resin binder containing a thermoplastic synthetic resin having excellent crack resistance, and a thermoplastic synthetic resin having excellent lamination; A raw material sheet for metal sintered body comprising a mixed powder of 10-30% by weight of a high melting point metal powder having a higher melting point than that of the magnetic alloy powder and which is easily welded. 17. The raw material sheet for metal sintered body according to claim 16, wherein the synthetic resin binder contains thermoplastic synthetic resin having excellent lamination property of 30 to 70% by weight with respect to the thermoplastic synthetic resin having excellent crack resistance. The raw sheet for metal sintered body according to claim 16, wherein the synthetic resin binder is added in an amount of 1-10% by weight based on the sinterable metal powder. 17. The raw sheet for metal sintered body according to claim 16, wherein the magnetic alloy powder is any one of Ni magnetic alloy powder, Fe magnetic alloy powder, and Co magnetic alloy powder. The raw material sheet for metal sintered body according to claim 16, wherein the high melting point metal powder is any one of Mo, W stainless steel WC, and Fe-Mo (ferro-molybdenum). The raw sheet for metal sintered body according to claim 16, wherein the high melting point metal powder is a mixture of two or more selected from Mo, W stainless steel WC, and Fe-Mo (ferro-molybdenum). 17. The raw sheet for metal sintered body according to claim 16, wherein the synthetic resin binder is a mixture of a tetrafluoroemulsion emulsion and an acrylic resin emulsion. The raw material sheet for metal sintered compact according to claim 16 or 17, wherein the thermoplastic synthetic resin having excellent lamination is any one of an acrylic resin, a polyethylene resin, and a butadiene acetate acetate copolymer. 18. The raw material sheet for metal sintered compact according to claim 16 or 17, wherein the synthetic resin binder is a mixture of a 1: 1 tetrafluoromethane emulsion and an acrylic resin emulsion. 7. The sintered body according to claim 1 or 6, wherein the sintered body is cooled in three cooling zones after sintering and then cooled at a slow speed in order to balance the sintered body in the primary cooling zone, and also slow in the secondary cooling zone. Cooling at a speed but faster than the first cooling zone, and in the third cooling zone, the cooling of the sintered body to room temperature again cooling the metal sintered body manufacturing method. A step of obtaining a sinterable metal powder by mixing 70-90% by weight of a soluble alloy powder with 10-30% by weight of a high melting point metal powder having a higher melting point than that of the soluble alloy powder and which is easy to weld. And 1-10% by weight of the sinterable metal powder in order to obtain a molded article having a uniform formation by mixing a synthetic resin binder, and sintering the molded product at a temperature above the liquidus line of the magnetic alloy powder. A method for producing a metal sintered body comprising the step obtained.

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