JPH04141505A - Manufacture of sintered compact body - Google Patents

Abstract

PURPOSE:To manufacture a cemented carbide sintered compact body having a long shape by taking-up a slurry-state raw material mixing fine metal particles, macromolecule binder, water and organic solvent after executing extrusion-malding and continuously drying and sintering it while drawing out the material. CONSTITUTION:The slurry-state raw material 5 is constituted by mixing the fine metal particles, macromolecule binder and water and/or organic solvent. The extrusion-molding is executed from a die 3 to this slurry-state raw material 5 by using a extrusion compact device 1. The extrusion-molding material 6 is once taken-up to a recessed groove 7 in a take-up drum 4. Successively, while drawing out the taken-up extrusion-molding material 6, the material is continuously dried and sintered. Further, fine ceramic particles are mixed to the slurry-state raw material. By this method, the cemented carbide sintered compact body having the optional shape, such as fine wire rod, plate, pipe, is manufactured.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is directed to metal microscopic bodies or ceramic microscopic bodies blended therewith, particularly hard-to-process single or composite materials, for example, wires, rods, etc. This invention relates to a method for continuously and efficiently manufacturing long sintered bodies having irregular cross-sectional shapes, such as plates or window frame materials, and the sintered bodies can be used to produce, for example, wire dot bins, etc. It is effectively used as a variety of ultra-hard, wear-resistant mechanical parts and cutlery materials.

[Prior art] Most metals can be cast into various shapes by taking advantage of their high-temperature melting properties, or can be made into wires, wires, etc. by forging, rolling, wire drawing, etc. by taking advantage of their malleability and ductility. It can be second-formed into any shape such as a rod or plate.

However, cemented carbide metals such as stellite have poor malleability and ductility, so apart from casting, secondary processing such as wire drawing and rolling is difficult, and since they are extremely hard, cutting is also difficult. Although it is a special feature as a cemented carbide metal material, it has not been fully utilized in industry due to its drawback of being difficult to process.

Composite materials (cermets), which have a metal matrix and contain ceramic powders and fibers made of metal oxides, metal nitrides, metal carbides, etc., are made of cemented carbide due to the dispersion strengthening effect of ceramics. It is attracting attention as an easily processable hard material because it has comparable hardness and can be subjected to some degree of secondary processing by utilizing the malleability and ductility of the matrix metal. However, the ceramics and metal matrix that make up the composite material have different physical properties when viewed individually, and the bonding strength between the two cannot be said to be perfect.
If the degree of processing is increased, peeling and breakage will occur at the interface between the two, making it difficult to obtain thin wires or thin plates.

[Problems to be Solved by the Invention] In view of these circumstances, the inventors of the present invention have developed a research method for the use and purpose of the above-mentioned difficult-to-work cemented carbide metals and ceramic dispersion-strengthened composite metal materials. As a result of conducting various researches in an attempt to provide a method for easily manufacturing sintered compacts with shapes according to the requirements, the following method was developed and a separate patent application was filed. That is, the method involves mixing cemented carbide metal particles or a mixture of general-purpose metal particles and ceramic particles with a pander made of a polymeric material and water and/or an organic solvent to obtain a slurry-like raw material, which is then extruded. This is a method in which it is formed into a linear or plate shape using a molding method, etc., then dried and sintered. With this method, even difficult-to-process materials such as cemented carbide and ceramics can be formed into arbitrary shapes with relatively simple operations. A sintered compact having the shape of can be obtained. By the way, when implementing this method, ideally the wires, plates, etc. that are continuously extruded from the forming equipment are sent directly to the drying and sintering equipment, and the operation is performed continuously, but in reality, Such continuous operation is not possible, so extruded wires and plates are cut to a certain length and then dried and sintered in a batch furnace. The reason for this is that the drying and sintering speed in a continuous furnace is significantly slower than the molding speed in an extrusion molding device.

Measures to carry out extrusion molding, drying, and sintering continuously under these circumstances include: ■ Using a long drying and sintering furnace to ensure sufficient drying and sintering time, or One possible method is to use a multi-type die in the extrusion molding device, lower the extrusion speed, extrude multiple wire rods or plates, and send them simultaneously to the drying and sintering furnace.

However, in order to realize method (1) above, a very long drying and sintering furnace is required, so it is difficult to adopt this method in consideration of the cost of constructing the furnace body and the expansion of the area occupied by the equipment. On the other hand, when method (2) is adopted, it is difficult to obtain a uniform sintered compact for the following reasons.In other words, it is difficult to maintain a uniform discharge speed and density of the discharged material from each multi-type die. This is difficult even with resin in a molten state, and it is virtually impossible to discharge extrudates from each multi-die at the same speed and density with a slurry-like raw material that is a dispersion of microscopic particles. can be,
If extruded products running at various running speeds are fed to the drying/sintering furnace, the sintering time for each will vary, resulting in different sintering completion states, making it impossible to obtain sintered products at a reasonable price.

For the reasons mentioned above, a method of continuously extruding, drying and sintering using a slurry raw material has not been implemented. Since the long products are cut to a certain length and then dried and sintered in a batch process, it is not possible to obtain very long wires or plates.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to manufacture a sintered body by extrusion molding, drying and sintering using the slurry-like raw material as described above. In particular, it is an object of the present invention to provide a method that enables continuous drying and sintering of an extrusion molded product, thereby making it possible to smoothly produce a long sintered body.

[Means for Solving the Problems] The configuration of the present invention that has achieved the above object is to mix metal microspheres or a mixture of metal micros and ceramic micros with a polymer binder and water and/or an organic solvent. The gist is that the slurry-like raw material obtained by mixing with It is.

[Function] The present invention was developed as a method for producing a sintered compact made of a metal, particularly a difficult-to-process cemented carbide metal, or a ceramic dispersion-strengthened composite metal material made by blending ceramics with the above-mentioned metal. It is something. If only metal is used as a raw material, a cemented carbide sintered body can be obtained by using a cemented carbide metal, but in the case of a ceramic dispersion strengthened type, even if a general-purpose metal is used, a cemented carbide sintered body cannot be obtained. Therefore, in the following explanation, we will explain cases in which cemented carbide is used as a raw material and cases in which a combination of general-purpose metals and ceramics are used as raw materials, but this is not intended to specify the raw material of the present invention. do not have.

In carrying out the present invention, first, microscopic objects of cemented carbide (including microscopic objects in the form of particles, plates, flakes, short fibers, scales, etc.), or microscopic objects of general-purpose metals and microscopic objects of ceramics, etc. The slurry material is mixed with a polymer substance that acts as a binder and water and/or an organic solvent that acts as a fluidizing agent in the extrusion molding process to form a slurry raw material. Form into shape. In the present invention, this extruded product is once wound up, kept in an undried and flexible state, and then unwound and sent to a drying/sintering furnace where it is continuously dried and sintered under predetermined conditions. . With this method, extrusion molding and drying/sintering are discontinuously combined through the winding and holding process, but rather, this allows the extrusion molding speed and drying/sintering speed to be separated from each other. can be adjusted to. Moreover, after extrusion molding, the rolled-up molded product remains flexible unless the fluidizing agent (water and/or organic solvent) contained therein evaporates and is removed. A long sintered compact can be obtained by sequentially drawing out the material and drying and sintering it.

Although the extruded product retains its shape to some extent due to the bonding force of the polymer binder, it is so weak that it deforms even when subjected to a small external force, and the cross-section may change due to the tension during winding. There is a possibility that the dimensions and shape may change, so when winding, for example, Figure 1 (plan explanatory diagram of the main parts, 1 is the extrusion molding device, 2 is the slurry, L-3 is the die, 4 is the winding drum, 5 is a raw material slurry, 6 is an extruded product, 7 is
As shown in (respectively, the grooves are grooves), a groove 7 having a size and shape corresponding to the cross section of the extruded product 6 is formed in the winding drum 4, and the groove 7 prevents the deformation of the extruded product 6. It is best to wind it up while preventing it.

In this case, if the molded product is rolled out and dried and sintered within a relatively short period of time after winding, the molded product will not dry out and lose its flexibility, but If the waiting time for the product to close is long, the water and/or organic solvent in the wound product may evaporate, causing the product to lose its flexibility and may break during the feeding process. In such cases, the rolled extrudate is placed in a moisturizing atmosphere (e.g. 80-90% R,H at 10-20°C).

It is desirable to maintain the water and/or organic solvent at a certain level (at a certain level) and prevent the volatilization of water and/or organic solvent. If a process is provided in which the rolled products are held in a constant moisture-retaining atmosphere in this way, multiple rolled products kept in the same moisture-retaining atmosphere can be simultaneously unwound from each winding drum and dried. - Can be sintered, and the total time required for drying and sintering can be significantly shortened.

The cemented carbide used in the present invention includes all hard-to-process cemented carbide metals and cemented carbide alloys, such as stellite (Co-Cr-W alloy), wc-Co series, and WC.
-TiC-Co system, TiC-MO2C-WC-Co
All conventionally known cemented carbide metals such as -Ni series and Tic-Mo2C-Ni series are applicable. On the other hand, general-purpose metals used in combination with ceramics include, for example, Fe, Ni, C'', Ti, etc., and various alloys containing these metals; I mentioned earlier that it is not something that can be excluded.

Ceramics include all ceramics that exhibit a dispersion strengthening effect on the above metals, including St, Ti, Al, and Zr.

Examples include oxides, nitrides, carbides, etc. of Ni, Nb, Mo, etc., and ceramic whiskers are also included in the ceramic microscopic bodies.

Cemented carbide metal particles and general-purpose metal particles can be produced by conventionally known methods such as atomization, reduction, thermal decomposition, and alloy decomposition methods, and ceramic particles can be produced by, for example, vapor phase production. Huan (evaporation condensation method, gas phase reaction method)
, liquid phase method (precipitation method, solvent evaporation method), solid phase method (pyrolysis method,
It is manufactured by any conventionally known method such as solid phase reaction method). The preferred size of these microscopic bodies varies depending on the cross-sectional dimensions (wire diameter and wall thickness) of the sintered antagonist, the target density, the shape of the microscopic body itself, etc., so it cannot be decided exactly, but it may be granular, flaky, etc. The preferred size is based on a scale-like shape with a small difference between the major axis and the minor axis, and the major axis is 50 μm or less, more preferably 44 μm.
m or less is recommended. In the case of short fibers, it is preferable to use those with a diameter of 10 μm or less and a length of 50 μm or less. However, if the size of the microscopic bodies is too large, it not only becomes an obstacle to making the molded body thinner and thinner, but also tends to cause voids to form inside the molded body after drying and sintering. However, even in cases like this)
By performing IIP treatment or the like, a solid sintered body without voids can be obtained.

Next, the polymer binder is an organic polymer binder that acts as a binder in the stage up to sintering and can be thermally decomposed and disappeared by heating for sintering, such as gelatin, casein, agar, gum arabic, and alginic acid. Natural organic polymer substances such as polyvinyl alcohol, polyacrylic acid, polyvinyl acetate, methylcellulose, carboxymethylcellulose, polyvinyl ether,
Preferred examples include synthetic organic polymeric substances such as polyvinylpyrrolidone, but in addition, polyalkylsilanes [eg, trade name manufactured by Nippon Sokako Co., Ltd.:
Polymer binders that have elements in their molecules that can be thermally decomposed to produce ceramics, such as "polysilastyrene", are also praised as preferred. Water and/or an organic solvent are used as the fluidizing agent, and the type of fluidizing agent is appropriately selected depending on the type of polymer binder and is capable of dissolving it, but the most common is water. Further, preferable organic solvents include alcohols, ketones, aromatic hydrocarbons, and halides of lower hydrocarbons. When water is used as a fluidizing agent, it is easy to obtain a sticky slurry, which improves moldability and shape retention of the molded product, making it easy to handle.On the other hand, when using an organic solvent, the metal oxide Even if non-oxide ceramics such as S i C-1PS i s Na are used as well as oxide ceramics such as the above, there is an advantage that they will not undergo oxidative deterioration.

In the present invention, the above-mentioned cemented carbide metal microspheres (^) or general-purpose metal microspheres and ceramic microspheres (^゛) are mixed with a polymer binder (B) and water and/or an organic solvent (C) to form a slurry. This is formed into a wire, rod, plate, etc. by extrusion molding as described above, then wound up, and then continuously dried and sintered while being unrolled to decompose and remove the polymer binder (or turn it into a ceramic material). ) and sintering the microscopic bodies to obtain a long sintered body. Microscopic particles (^) or (^°) during slurry preparation,
Polymer pander (B) and water and/or organic solvent (C
) is not particularly limited, but the most common is 2 to 15 parts by weight, more preferably 5 to 10 parts by weight of the polymer binder (B) per 100 parts by weight of the microscopic particles (A) or (^'). Part by weight, water and/or organic solvent (C) is 10-
The amount is 40 parts by weight, more preferably 12 to 30 parts by weight. In addition, when using metal microspheres and ceramic micros, the mixing ratio of both varies depending on the type of raw material microspheres and the target hardness of the sintered compact, so it cannot be set uniformly, but it can be set as a standard value. If shown, 0.2 to 1 part by weight of ceramic particles per 100 parts by weight of metal particles
00 parts by weight, more typically from 2 to 40 parts by weight. In preparing this slurry, the viscosity is 10" to 10" at a shear rate of 1 to 1000 sec-'.
It is desirable to control the blending amounts of the polymer binder (B) and water and/or organic solvent (C) so that the poise is 106 poise.

Although the conditions for drying and sintering are not particularly limited, it is preferable to carry out the drying and sintering under vacuum conditions in order to efficiently decompose and remove the polymer binder while preventing surface oxidation of the metal particles. However, it is of course possible to sinter in a reducing gas or inert gas atmosphere, and even when sintered in an atmospheric atmosphere, the sintered body is shielded from the outside air by the gas generated by thermal decomposition of the organic polymer material. Therefore, oxidation inside the sintered compact hardly occurs and does not pose a big problem. Furthermore, when a ceramic-forming polymer binder is used, ceramics made of nitride can be produced by sintering in a nitrogen or ammonia gas atmosphere. Sintering temperature is usually 1100-1500
The sintering temperature is approximately 1200 to 1400°C, but depending on the type of microscopic object, a sintering temperature outside this range may be preferable.

[Example] Using the blended raw materials shown in Table 1, 30~
Prepare a slurry by kneading for 40 minutes.

This slurry was supplied to an extrusion molding apparatus equipped with a screw of 25 m++aφ to extrude a linear product. In this case, the inner diameter of the discharge nozzle was varied in the range of 0.5 to 4 mmφ, and the extruded product was wound around 10 drums (diameter 125 mm x width 300 mm) with V-shaped spiral grooves on the surface, and heated to 15°C. , 90% R, H, and stored in a constant temperature and humidity room to prevent drying.

The molded bodies thus wound around 10 drums are then unrolled and sent to a continuous drying/sintering furnace at a maximum temperature of 1290°C for slurry 1, and at 1300°C under an ammonia gas atmosphere for slurry II. The mixture was sintered to obtain 10 linear sintered bodies, each 7 m long.

On the other hand, after taking out the extruded product, 0.5 to 1
I tried to dry and sinter the extruded product by leaving it for a while, and then paying it out from the winding drum in the same way as above, but when I left it indoors, the extruded product dried and lost its flexibility, and the molded product did not lose its flexibility during the feeding process. It was impossible to carry out continuous drying and sintering because it broke easily.

[Effects of the Invention] The present invention is configured as described above, and even if it is a difficult-to-process cemented carbide sintered compact made of a cemented carbide metal or a ceramic dispersion-strengthened composite metal, a long thin wire rod or plate can be used. , it became possible to easily manufacture sedge hats of any shape.

[Brief explanation of the drawing]

FIG. 1 is a sectional plan view of a main part showing how the extruded product used in the present invention is wound. 1... Extrusion molding device 2... Screw 3...
Die 4... Winding drum 5... Slurry 6... Extruded product 7... Concave groove

Claims (2)

[Claims] (1) A slurry-like raw material obtained by mixing metal microspheres, a polymer binder, and water and/or an organic solvent is extruded, the obtained extruded product is once rolled up, and then the rolled extruded product A method for manufacturing a sintered compact, characterized by continuous drying and sintering while drawing out a sintered body. (2) A slurry-like raw material obtained by mixing metal microspheres, ceramic micros, a polymer binder, and water and/or an organic solvent is extruded, and the resulting extruded product is once rolled up. A method for producing a sintered compact, characterized by continuously drying and sintering the extruded product while drawing it out.