JP2906030B2 - Ceramic-carbide composite sintered body and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to abrasive wear (hereinafter referred to as abrasive wear) of mass transportation equipment such as mixing, transportation and slurry transportation of granular powders, and civil construction equipment.
At the same time, it is concerned with abrasion and corrosion resistant materials that are used in parts that are susceptible to chemical corrosion wear.In particular, while maintaining the excellent chemical stability and abrasion resistance of sintered ceramics, it can be applied to the above machines and metal components. The present invention provides a highly reliable, high-quality ceramic-carbide composite sintered body that enables direct welding bonding of a sintered body and a method of manufacturing the same.

[0002]

2. Description of the Related Art Heretofore, this type is as follows. Various equipment that provides crushing and mixing of metals and ceramics, as well as civil engineering and construction machinery that crushes and transports earth and sand and rock, as well as the means of transporting them, have high abrasion properties for the target processing object, and the Significant wear due to contact. Further, in the paper industry, the chemical industry, the fertilizer industry, the food industry, and the like, in addition to the abrasive wear, combined wear with chemical corrosion occurs. For mere abrasive wear, cemented carbide is generally used in terms of strength and hardness. However, in addition, ceramic-based sintered bodies are mainly used in the field of wear-resistant materials requiring chemical resistance. The joining of the ceramic sintered body to the machine body or members is performed by mechanical joining methods such as screwing, shrink fitting, or cast-in, and bonding and activation with an adhesive, considering the conditions and environment in which the ceramic sintered body is used. Indirect material bonding methods such as ro-ro bonding are used.

[0003]

The above-mentioned prior art has the following problems. Mechanical joining methods such as screwing, shrink-fitting, or cast-in of a ceramic sintered body and a general metal member prevent compression and tensile stress from occurring in the ceramic sintered body due to the nature of the joint. However, due to the generation of the stress, there is a problem that the strength of the ceramic sintered body is reduced and the ceramic sintered body is broken during use. In addition, these mechanical joining methods have a problem in that high stress is easily generated locally in the ceramic component, which causes sudden destruction of the ceramic component. In addition, if you try to join with a weak force worried about the occurrence of this stress, the joint may become loose due to changes in the use environment (temperature, load), and not only will not work properly, but if it is severe, vibration and impact There was also a problem that the ceramic component was destroyed, causing serious damage to a series of surrounding systems.
On the other hand, the method using an adhesive is simple, but is susceptible to an impact load, and in many cases, has a heat resistance problem that at a temperature of 200 ° C. or higher, the adhesive strength is reduced and the film cannot be used. In addition, when an activation metal such as titanium or zirconium is added, and the joining is performed by an activation filter which is improved so that it can be used for joining a ceramic and a metal, a large stress is likely to remain in both after the welding. The extent of the residual stress increases as the bonding area increases,
The larger the difference in thermal expansion between the two and the higher the bonding temperature, the larger the difference. Hard ceramics having excellent wear resistance have a thermal expansion coefficient of 10 × 10 ⁻⁶ or less in many cases. On the other hand, stainless steel is mainly used as a metal member in consideration of corrosion resistance. The expansion rate is 18 × 10 ^-6
And quite large. Therefore, in many cases, deformation of the joined body and cracking of the ceramic layer are unavoidable. This not only increases the post-joining processing cost, but also contributes to the sudden breakdown of the ceramic due to residual stress,
There is a problem that the reliability as a structural component is significantly impaired. Further, these active fillers are materials having poor corrosion resistance, which is contrary to the significance of using ceramic sintered bodies for the purpose of improving corrosion resistance. The present invention has been made in view of the above circumstances, and a ceramic-carbide composite sintered body having a cemented carbide part having the property of being directly weldable to steel or stainless steel as a part thereof is provided with a temperature gradient. The present invention is to provide a wear-resistant material made of a highly reliable ceramic-carbide composite sintered body excellent in wear resistance and corrosion resistance by simultaneously sintering integrally using an electric current sintering method having a resistance, and a method of manufacturing the same. It is assumed that.

[0004]

Means for Solving the Problems In order to achieve the above object, the present invention is as follows. The present inventors have continued research to solve the above-mentioned problems in the method of fixing the wear-resistant material to the machine body. As a result, in the electric sintering method under the pressurized condition, the molding outer frame is designed as a mold having one of the energizing paths, the thickness of the outer molding frame is appropriately adjusted, By appropriately controlling the amount of heat generation and the amount of heat radiation, a temperature gradient can be provided as needed in the direction of the pressing axis of the raw material portion of the sintered body. By this method, two or more materials having different sintering temperatures can be sintered. One of the present inventors has found that it is possible to perform sintering in a single state in a state where there is no excess or deficiency in the state and the generation of residual stress is extremely small. The present invention provides a cemented carbide-based wear-resistant material having direct weldability and a method for producing the same. The present invention is based on Japanese Patent Application No. 6-113696,
This was achieved as a result of further research. That is, the present invention provides a weldable layer 1b of a tungsten carbide-based cemented carbide having a metallic binder phase content of 15 to 40% by weight,
Wear-resistant layer 1 of ceramic sintered body made of at least one of alumina, zirconia, silicon carbide, and silicon nitride
a-molded ceramic-carbide composite sintered body
And a method of manufacturing by an electric current sintering method using upper and lower punches 3 and 4.
From the a1 side, it increases continuously and / or stepwise to the weldable layer raw material powder 1b1 side, and the jig 5 is placed on the jig 5 so that the end face of the lower punch 4 on the weldable layer raw material powder 1b1 side matches the end face of the molding outer frame 2. And the molding outer frame 2 is provided with at least one current-carrying path, thereby forming a temperature gradient in the pressing axis direction of the ceramic-ceramic-based sintered material powder 11 during energization, and Sintering of sintered body raw material powder 11 keeps the ceramic sintered body excellent chemical stability and wear resistance, and is a wear-resistant material made of a ceramic-carbide composite sintered body that enables direct welding to a machine body. And a method for producing the same. In the normal electric sintering method, a molding outer frame made of graphite and upper and lower punches are used. First, the powder to be sintered is filled in a state in which the lower punch is set in the molding outer frame, and then the upper punch is pressed and pressed. In this state, a direct current or an alternating current or a superimposed current is passed through the upper and lower punches, and the sample is sintered by Joule heat using the electric resistance of the sample to be sintered. Here, the molding die is designed so that the molding outer frame becomes one energization path,
Also, when the thickness of the molding outer frame is changed in the direction of the pressing axis, the amount of heat generation and the amount of heat can be controlled in accordance with the change in the thickness, and a temperature gradient including irregularities in the direction of the pressing axis of the sample portion. It turns out that you can put on. The electrical resistance is high in the part where the molded outer frame is thinner than the others, the amount of heat generated under a constant current is large, and the temperature is high. On the other hand, in the thickened portion, on the other hand, the resistance is low, the heat generation is small, and a low temperature region is formed. By this method, the temperature of the material requiring high temperature for sintering can be raised by making the thickness of the surrounding outer frame thinner than the other, and at the same time, the unnecessary temperature rise can be suppressed on the other material side. . If a large temperature gradient is required, insert a jig with a large heat capacity on one side and use it as a heat sink.If the rate of temperature rise can be increased, transient jigs before the temperature reaches equilibrium A method using a temperature distribution can be used together. The degree of the change in the thickness of the molded outer frame here needs to be in a range that allows the molded outer frame to function as a pressure vessel while having a low pressure, and that its strength is acceptable.

[0005]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a wear-resistant layer 1a made of a ceramic sintered body.
Layer 1b made of tungsten and tungsten carbide based cemented carbide
FIG. 1 is a cross-sectional view of a ceramic-ultrahard composite sintered body 1 formed by directly sintering and joining. 2 and 3 show a cross section of a ceramic-carbide composite sintered body 1 in which an intermediate layer 1c composed of a mixture of a wear-resistant layer 1a and a weldable layer 1b is put between the two layers and sintered and joined. FIG. In FIG. 3, 1c1 is a lower intermediate layer, and 1c2 is an upper intermediate layer. The intermediate layer 1c has a role not only to assist the joining of the two but also to alleviate the generation of residual stress due to shrinkage after sintering, and the composition of the intermediate layer is not necessarily a half-and-half mixture. No need, depending on the thickness, size and shape of both layers,
In addition, depending on the difference in thermal expansion between the two layers, the composition can be appropriately selected within a range in which each composition of both layers is an end component. Whether direct joining or joining with an intermediate layer is used depends on the difference in thermal expansion between the ceramic sintered body constituting the wear-resistant layer 1a and the cemented carbide constituting the weldable layer 1b, and the chemical affinity of both layers. Is selected, and is appropriately selected depending on the method of use. As a rough guide, the difference in thermal expansion coefficient between the materials constituting both layers is 1 × 1
For combination of the 0 ^-6, it can be employed directly sintered joint of FIG. The thickness of the intermediate layer 1c and the number of layers are appropriately determined depending on the difference in thermal expansion between the ceramics and the cemented carbide constituting both layers and the environment in which they are used. Considering the similarity of sintering temperature and sinterability (sintering familiarity) with the cemented carbide constituting the weldable layer, in addition to the abrasion resistance and corrosion resistance of the wear-resistant layer 1a according to the present invention, many are considered. Among the ceramics, alumina, zirconia, silicon carbide (hereinafter, referred to as
It is made of a ceramic sintered body made of at least one of SiC) and silicon nitride (hereinafter, Si3N4). The wear-resistant layer 1a is made of, for example, alumina-Si in consideration of a difference in thermal expansion from the cemented carbide constituting the weldable layer 1b.
C, alumina-Si3N4, zirconia-SiC, zirconia-Si3N4, alumina-zirconia-SiC,
A combination such as alumina-zirconia-Si3N4 can be used. Such a combination of a ceramic having a large coefficient of thermal expansion and a ceramic having a small coefficient of thermal expansion as compared with a cemented carbide is effective in reducing residual stress after sintering and joining. In the single sintering of alumina, zirconia, SiC, and Si3N4, a small amount of a sintering aid such as magnesium oxide (hereinafter, MgO), yttrium oxide (hereinafter, Y2O3), boron carbide, or boron is generally used to promote the sintering. However, also in the present invention, these materials can be added and used for the purpose of assisting sintering as long as the wear resistance and corrosion resistance of the ceramic sintered body are not impaired. In order to weld a cemented carbide to stainless steel or a steel material with a high joining strength, the amount of the metal-based binder phase needs to be 15 to 40% by weight. The weldable cemented carbide serves the purpose of ensuring the weldability to the machine body, and at the same time, plays a role of mechanically reinforcing the wear-resistant layer 1a formed of the sintered ceramic sintered body. The amount of the metal-based binder phase in the cemented carbide part constituting the weldable layer capable of fulfilling this role was at most 40% by weight, preferably 30% by weight. 4
If the content is 0% by weight or more, the properties of the cemented carbide become closer to the properties of the binder phase metal than the properties of the cemented carbide. FIG. 5 schematically shows an electric current sintering method for explaining one embodiment of the present invention. 1 shows a sintered sample structure for producing a ceramic-carbide composite sintered body 1 having an intermediate layer 1c between a wear-resistant layer 1a and a weldable layer 1b, which has a large amount of a binder phase and therefore requires a high temperature for sintering. The raw material powder 1b1 to be welded is filled on the lower punch 4, and the raw material powder 1c10 for the intermediate layer and the raw material powder 1a1 for the wear-resistant layer are laminated thereon. The thickness of the molded outer frame 2 in the pressing axis direction is adjusted according to the required sintering temperature of each layer and the thickness of each layer before sintering. In the present embodiment, it is involved in the sintering of the raw material powder 1b1 of the weldable layer. Example of a cross-sectional shape in which a thick part and a thin part involved in sintering of the wear-resistant layer raw material powder 1a1 are continuously reduced in thickness at a part containing the intermediate-layer raw material powder 1c10 and connected. Is shown. In the sintering step, first, the molded outer frame 2 having been thickened as described above is placed on a jig 5 having a larger sectional area than the lower punch 4.
And the lower punch 4 is inserted, and the lower punch 4 and the end surface of the molding outer frame 2 are set on the jig 5 so as to be flush with each other. Next, the raw material powder 1b1 for the weldable layer, the raw material powder 1c10 for the intermediate layer, and the raw material powder 1a1 for the wear-resistant layer are laminated and filled in this order. In the figure, reference numeral 11 denotes a ceramic-ultrahard composite sintered body raw material powder. After the upper punch 3 is put into this and pressed lightly, it is set in the electric sintering machine. Then, after pressurizing to a predetermined pressure, power supply is started by the power supply 8 via the upper electrode 6 and the lower electrode 7, and heating and sintering are performed. By arranging the lower surface of the lower punch 4 so as to be in contact with the lower surface of the molding outer frame 2, heat conduction to the jig 5 having a large heat capacity is promoted, and the thickness of the molding outer frame 2 is increased. This has the effect of further suppressing the temperature rise in the portion where the height is increased, and a larger temperature gradient can be formed with the high temperature generating portion where the thickness is reduced. The size of the jig 5 is adjusted according to the required temperature gradient. The material of the jig 5 is practically graphite.
The shape of the molded outer frame 2 is an important component of the present invention. The material is heat-resistant and is not particularly limited as long as it is a conductive material, but graphite is suitable for practical use. The same applies to the upper and lower punches. FIGS. 7 to 9 show the vertical cross-sectional shapes of the molded outer frame 2 that can be used in the method for producing a ceramic-carbide composite sintered body of the present invention. 10 to 13
Is a molded outer frame 2 that can be used in the manufacturing method according to the present invention.
And the cross-sectional shape of the ceramic-ultrahard composite sintered material powder 11, which is appropriately selected according to the required final shape of the wear-resistant material. FIG. 7 shows a case where the thickness of the molded outer frame 2 changes in steps, which is used when the wear-resistant layer 1a and the weldable layer 1b which require a relatively steep temperature gradient are directly joined. On the other hand, FIGS. 8 and 9 show an example in which the thickness of the molding outer frame 2 changes continuously, which is used when a relatively gentle temperature gradient is used. Specifically, the thickness of the wear-resistant material is large. Also, it is used when the thickness of the intermediate layer can be made large. Regarding the cross-sectional shape of the molded outer frame, FIG.
In the center of the cylinder, a cylindrical hollow was opened.
A square tubular center hole was opened at the center of the cylinder.
The one with a cylindrical bore at the center of the prism, FIG.
Each of the prisms has a square hollow hole at the center of the prism. In the manufacturing method according to the present invention, the degree of fitting between the outer molding frame 2 and the upper and lower punches 3 and 4 is particularly important for realizing a target temperature gradient during energization. The clearance between the punches 3 and 4 is 0.02 if the conductive material is not particularly filled between them.
mm, preferably 0.01 mm or less.

[0006]

【Example】

Example 1 Referring to FIG. 4, 20 wt% of Si3N4 powder having an average particle size of 0.2 μm was added to alumina powder having an average particle size of 0.5 μm.
, Mixed with a ball mill and dried to obtain a powder (hereinafter, referred to as
Alumina-20% Si3N4) as raw material powder for wear-resistant layer 1a
1, and tungsten carbide (hereinafter, WC) powder having an average particle size of 1.5 μm is coated with nickel of 1 to 5 μm (hereinafter, N).
i) A powder (hereinafter referred to as WC-30% Ni) obtained by adding 30% by weight of a powder, mixing with a ball mill and drying was used as a raw material powder 1b1 for a weldable layer. In the figure, reference numeral 11 denotes a ceramic-ultrahard composite sintered body raw material powder. The molded outer frame 2 for electrical sintering has a sectional shape shown in FIG.
A mold made of graphite having a height of 45 mm and a medium hole diameter of 40 mm, which becomes 0, was used. The thickness of this molded outer frame was 6.5 mm from one end to 25 mm, and 17.5 mm from the other end to 20 mm.
And In addition, the holes for temperature measurement have depths of 2 mm from the outer periphery of the molded outer frame at a position corresponding to a wear-resistant layer of 20 mm from the top and a position corresponding to a weldable layer of 15 mm from the bottom, with the thin side of the molded outer frame facing upward. Drilled holes of 0.5 mm, 16 mm and 3 mm in diameter were made. Upper punch 3 has a diameter of 40 mm and a height of 30 mm
The lower punch 4 has a diameter of 40 mm and a height of 10 mm.
As the jig 5, a graphite block having a diameter of 75 mm and a height of 40 mm was used. The clearance between the upper and lower punches and the inner diameter of the molded outer frame was 0.01 mm or less. Using these sintered parts, first, the forming outer frame 2 is arranged on a jig having a diameter of 75 mm so that the thinner side is upward, so as to be concentric with the outer diameter of the jig 5. The lower punch 4 is pushed into the lower punch, and WC-30% Ni powder is filled as the weldable layer raw material powder 1b1 so as to have a thickness of 10 mm on the lower punch, and alumina is formed thereon as the wear-resistant layer raw material powder 1a1. placed so as to have a thickness of 10mm the 20% Si3 N4 powder was pressurized at 100 Kg / cm ² by setting the upper punch 3. The sintering sample configuration was set in an electric sintering machine, and the pressure was increased to 500 kg / cm ² to start energization. The temperature was raised to 1320 ° C. in about 5 minutes at the measurement temperature at the position corresponding to the wear-resistant layer, and the temperature was maintained for 3 minutes. When the temperature reached 1320 ° C. at the position corresponding to the wear-resistant layer, the temperature at the position corresponding to the weldable layer was 1100 ° C., and after holding for 3 minutes, it was 1110 ° C. The shape of the sintered body collected after cooling was 40 mm in diameter and about 11.5 mm in height. This sintered body was cut in half by a plane parallel to the pressing direction, and one of the cut surfaces was polished and the cross section was observed. There were no cracks or porosity in the cross section, and it was strongly sintered integrally. The hardness of the sintered body is 1980 Kg / mm ^{2 for} the wear-resistant layer and 104 for the weldable layer.
It was 0 kg / mm ² . Also, using the other half,
An arc welding test was performed on a WC-30% Ni weldable layer using a nickel welding rod on stainless steel having a diameter of 50 mm and a thickness of 40 mm. There was no damage to the cemented carbide side, and welding was performed with sufficiently high strength. Was possible and had a practical impact strength. Further, using the sintered body welded to the stainless steel, a wear resistance test of the wear resistant layer was performed. The test was carried out using a # 80 silicon carbide (Si
C) Abrasive paper is stuck, and the abrasion-resistant layer is pressed against the abrasive paper while the polishing board is rotated at about 50 rpm while water is applied thereon, and the weight loss after about 5 minutes is measured. The weight loss by this method was as small as about 0.9 mg, indicating good abrasion resistance. Example 2 Referring to FIG. 5, 50% by weight of an SiC powder having an average particle size of 0.5 μm was added to alumina powder having an average particle size of 0.3 μm, mixed with a ball mill, and dried to obtain a powder (hereinafter, referred to as alumina-5).
0% SiC) as the wear-resistant layer raw material powder 1a1, and 15% by weight of each of WC powder having an average particle size of 9 μm and Ni powder of 1 to 5 μm and cobalt (hereinafter, Co) powder having an average particle size of 1 μm. , Mixed with a ball mill and dried to obtain a powder (hereinafter referred to as WC-15% Ni-15% Co) used as the weldable layer raw material powder 1b1. Also, alumina-50%
60% by weight of SiC powder and WC-15% Ni-15% Co
A powder obtained by mixing and drying 40% by weight of a powder in a ball mill (hereinafter referred to as 60% (alumina-50% SiC) -40%
(WC-15% Ni-15% Co)) was used as the intermediate layer raw material powder 1c10. In the figure, reference numeral 11 denotes a ceramic-ultrahard composite sintered body raw material powder. Forming outer frame 2 for electrical sintering
A graphite mold having a cross-sectional shape shown in FIGS. 8 and 10 and having a concentric height of 40 mm and a medium hole diameter of 30 mm was used. The thickness of the molded outer frame 2 was 7.5 mm from one end to 20 mm, 15 mm from the other end to 15 mm, and the thickness was linearly increased in cross section from 7.5 mm to 15 mm. With the thin side of the molded outer frame 2 as the top, a position corresponding to a wear-resistant layer of 19 mm from the top and 1 mm from the bottom.
Drilled holes of 3 mm in diameter were formed at positions corresponding to a weldable layer of 4 mm from the outer periphery of the molded outer frame to a depth of 3.5 mm, respectively.
It was pierced so as to be 1 mm, and the temperature during sintering was measured at these two places. Upper punch 3 and lower punch 4 each have a height of 30
mm, 10 mm, and the clearance between the inner diameter of the molded outer frame and the punches was 0.01 mm. As shown in FIG. 5, the jig 5 has an outer diameter of 55 mm and a height of 50 mm.
A graphite block of mm was used. Using these sintered parts, first, the forming outer frame 2 is placed on a jig 5 having a diameter of 55 mm with the thinner side facing upward, and the outer diameter of the jig 5 and the outer shape of the forming outer frame 2 are determined.
Are arranged so that their outer diameters are concentric.
The lower punch 4 of 0 mm was inserted so as to be in contact with the upper surface of the jig 5. Next, on the lower punch 4, WC-15% Ni-15% Co powder as the weldable layer raw material powder 1b1 and 60% as the intermediate layer raw material powder 1c10 (alumina
50% SiC) -40% (WC-15% Ni-15% C
o) Powder, alumina-5 as the wear-resistant layer raw material powder 1a1
0% SiC powder was filled under pressure at a pressure of 100 kg / cm ² so as to have a thickness of 5 mm, and the upper punch 3 was set. The sintering sample configuration was set in an electric sintering machine, pressurized at a pressure of 500 kg / cm ² , and energization was started. The temperature was raised to 1380 ° C. in about 6 minutes at a measurement temperature at a position corresponding to a wear-resistant layer of 19 mm from the top of the molded outer frame 2 and maintained at that temperature for 2 minutes. The measured temperature is 13
When the temperature reached 80 ° C., the measured temperature at the position corresponding to the weldable layer 14 mm from the bottom was 1110 ° C., and after holding for 2 minutes, 1
125 ° C. The sintered body recovered after cooling is 30m in diameter
m and a height of about 7.5 mm. Example 1
When evaluated by the same method as in the above, there were no cracks or pores in the cross section, and it was firmly and integrally sintered. The hardness of this sintered body was 2450 kg / mm ^{2 for} the wear-resistant layer and 1350 kg for the intermediate layer.
Kg / mm ^2, was 1010Kg / mm ² in weldable layer. Furthermore, when a welding test of a weldable layer to stainless steel was attempted using the other half in the same method and procedure as in Example 1, welding of practical strength was possible. Also,
Using this welding sample, a wear resistance test of the wear resistant layer was performed by the same means and method as in Example 1.
The weight loss was about 0.8 mg, indicating good abrasion resistance. Comparative Example 1 An outer diameter of 60 mm, a height of 40 mm, and a medium hole diameter of 30 m made of graphite of the same material as used in Example 2 as a molded outer frame.
m simple cylinder was used. Upper and lower punches have a diameter of 30m and a height of 2
Three types of raw material powders similar to those in Example 2 were used, each having the same shape of 0 mm. After setting the lower punch on the outer frame of the simple cylinder, WC-15% Ni-15% Co as the weldable layer raw material powder and 60% (alumina-50% SiC ) -4
0% (WC-15% Ni-15% Co), alumina-50% SiC as a wear-resistant layer material powder, each having a thickness of 5 m.
m, pressurized and filled at 100 kg / cm ² , and set an upper punch. In this state, the upper and lower punches were adjusted so that the degree of punching from the outer frame was the same. There are two holes for temperature measurement at a position equivalent to a wear-resistant layer 15 mm from one end of the molded outer frame and a hole 3 mm in diameter 11 mm deep from the outer periphery of the molded outer frame at two positions corresponding to a weldable layer 15 mm from the other end. Was processed. This sintered sample configuration was set between the upper and lower electrodes, and energization was started while pressurizing to 500 kg / cm ² . The temperature was raised to 1380 ° C. in 6 minutes by measuring the temperature at a position corresponding to a wear-resistant layer of 15 mm from one end of the molded outer frame, and the temperature was maintained for 2 minutes to stop energization, and the sintering was completed. The temperature measured at the other temperature-measuring point weldable layer during sintering at 1380 ° C. was also 1380 ° C., and no temperature difference was observed.
After cooling, the collected outer frame is placed between the upper and lower punches.
Several blow-offs of several mm diameter with metallic luster were observed. The sintered body was firmly joined to the outer frame and upper and lower punches, and the mold was broken to recover the sintered body. The thickness of the sintered body was about 6 mm, and there were some large chips. This sintered body was observed by the same procedure and method as in Example 2. Chips and pores were observed on the outer periphery of the cross section, and several lateral cracks were observed in the wear-resistant layer. Further, by the same method as in Example 2,
When a welding test was performed on stainless steel, cracks occurred at the interface between the weldable layer and the weld bead, making welding impossible. In addition, an increase in cracks in the wear-resistant layer was observed by this welding. It is considered that the sintering temperature on the weldable layer side was too high, the metal component in the cemented carbide flowed out, and the amount of the metal-based binder phase in the cemented carbide became 15% or less, making welding impossible. Example 3 Referring to FIG. 6, powder obtained by adding 35% by weight of Co powder having an average particle size of 1.5 μm to WC powder having an average particle size of 5 μm, mixing with a ball mill, and drying (hereinafter, WC-35% Co) Is a weldable layer raw material powder 1b1, and 5% by weight of Y2O3 powder as a sintering aid is added to zirconia powder having an average particle size of 1 μm.
Is added, mixed and dried to obtain a powder (hereinafter, zirconia-
5% Y2O3) was used as the wear-resistant layer raw material powder 1a1. Also, zirconia-5% Y2O3 powder 40% by weight
And WC-35% Co powder 60% by weight were mixed and dried to obtain a powder (hereinafter referred to as 40% (zirconia-5% Y2O
3) -60% (WC-35% Co)), a powder obtained by mixing and drying 75% by weight of zirconia-5% Y2O3 powder and 25% by weight of WC-35% Co powder (hereinafter 75%).
(Zirconia-5% Y2O3) -25% (WC-35%
Co)) was used as the intermediate layer raw material powders 1c11 and 1c21. 9 and 10, a graphite mold having a height of 45 mm and a medium hole diameter of 30 mm is used. The thickness of the outer frame 2 is 20 mm from one end.
The distance from the other end was 8 mm, and the distance from the other end to 15 mm was 20 mm, and the distance from 8 mm to 20 mm was continuously connected by a curve having a curvature of about 5 mm in cross section. The hole for temperature measurement is 17.17 from the top, with the thin side of the outer frame 2 facing upward.
Drilled holes having a diameter of 3 mm were formed at a position corresponding to a wear-resistant layer of 5 mm and a position corresponding to a weldable layer of 12.5 mm from the other end so as to have a depth of 2.5 mm and 16 mm from the outer periphery of the molded outer frame, respectively. As upper punch 3, diameter 30mm, height 30m
m, a graphite punch having a diameter of 30 mm and a height of 10 mm was used as the lower punch 4, and a graphite block having a diameter of 80 mm and a height of 40 mm was used as the jig 5. The clearance between the upper and lower punches and the inner diameter of the molding outer frame is 0.01 mm
Met. First of all, using these sintered parts,
m on a jig 5 with the thinner wall facing up
Were arranged so that the outer diameter of the jig 5 and the outer diameter of the molding outer frame were concentric, and the lower punch 4 was pushed into the molding outer frame so as to be in contact with the upper surface of the jig 5. Next, this lower punch 4
WC-3 as a weldable layer raw material powder 1b1
5% Co with a thickness of 8 mm and a lower intermediate layer raw material powder 1c11 of 40% (zirconia-5% Y2O3) -60% (W
C-35% Co) is 2.5% thick and 75% (zirconia-5% Y2O3) as the upper intermediate layer raw material powder 1c21.
-25% (WC-35% Co) with a thickness of 2.5 mm and zirconia-5% Y as a wear-resistant layer raw material powder 1a1 thereon
2O3 is filled to a thickness of 8 mm, and 100 kg /
Pressure was applied at cm ² , and the upper punch 3 was set. The sintering sample composition was set in an electric sintering machine, and the pressure was 400 kg / cm.
^The pressure was increased to ² to start energization. The temperature was raised to 1280 ° C. in about 5 minutes at the measurement temperature at the position corresponding to the wear-resistant layer, and the temperature was maintained for 1.5 minutes. When the temperature reached 1280 ° C. at the position corresponding to the wear-resistant layer, the temperature at the position corresponding to the weldable layer, which is another measurement point, was 1060 ° C., and the temperature after holding for 1.5 minutes was 1090 ° C. The shape of the sintered body recovered after cooling is 30mm in diameter and about 13mm in height
Met. This sintered body was observed in the same manner as in Example 1. The hardness of the sintered body is 1150 Kg / mm ² in the wear-resistant layer,
It was 980 kg / mm ² in the weldable layer. When a welding test was performed on stainless steel using the same method and procedure as in Example 1, welding with sufficiently high strength was possible. Further, in the wear resistance test of the wear resistant layer using the sample of this welding, the weight loss was about 1.3 mg, showing good wear resistance.

[0007]

Since the present invention is configured as described above, the following effects can be obtained. As described above, according to the present invention, in the production of a ceramic-carbide composite sintered body by the electric current sintering method, the thickness of the forming outer frame in the pressing axis direction is determined by sintering each constituent material to be sintered. By appropriately adjusting the temperature according to the temperature, the ceramic-ultrahard composite sintered body raw material powder can be sintered without excess or deficiency under a temperature gradient suitable for the constituent material. According to this method, it is possible to stably produce a ceramic-carbide composite sintered body having excellent wear resistance and corrosion resistance as well as properties capable of being directly welded to stainless steel or steel in a short time and at low cost.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a ceramic-carbide composite sintered body in Example 1.

FIG. 2 is a longitudinal sectional view of a ceramic-carbide composite sintered body in Example 2.

FIG. 3 is a longitudinal sectional view of a ceramic-carbide composite sintered body in Example 3.

FIG. 4 is a longitudinal sectional view illustrating a method for manufacturing a ceramic-carbide composite sintered body in Example 1.

FIG. 5 is a longitudinal sectional view illustrating a method for manufacturing a ceramic-carbide composite sintered body in Example 2.

FIG. 6 is a longitudinal sectional view illustrating a method for manufacturing a ceramic-carbide composite sintered body in Example 3.

FIG. 7 is a longitudinal sectional view showing a state in which the thickness of a molded outer frame changes in steps.

FIG. 8 is a longitudinal sectional view showing a state where the thickness of a molded outer frame is continuously changing.

FIG. 9 is a longitudinal sectional view showing a state where the thickness of the molded outer frame is continuously changing.

FIG. 10 is a sectional view taken along line AA.

FIG. 11 is a sectional view showing another embodiment taken along line AA.

FIG. 12 is a sectional view showing another embodiment taken along line AA.

FIG. 13 is a sectional view showing another embodiment taken along line AA.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 ceramic-carbide composite sintered body 1a wear-resistant layer 1b weldable layer 1c intermediate layer 2 formed outer frame 3 upper punch 4 lower punch 5 jig 6 upper electrode 7 lower electrode 8 power supply 11 ceramic-carbide composite sintered body Raw material powder 1a1 Wear-resistant layer raw material powder 1b1 Weldable layer raw material powder 1c1 Lower intermediate layer 1c2 Upper intermediate layer 1c10 Intermediate layer raw material powder 1c11 Lower intermediate layer raw material powder 1c21 Upper intermediate layer raw material powder

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideo Ando 1 of 594 Akahira, Akabira-shi, Hokkaido Sumitomo Coal Mining Co., Ltd. Hokkaido Technical Research Institute (56) References JP-A-61-270271 (JP, A) Hei 6-173009 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C04B 37/02 B22F 7/06

Claims (2)

(57) [Claims] 1. A wear-resistant layer (1a) of a ceramic sintered body comprising at least one of alumina, zirconia, silicon carbide and silicon nitride, and a tungsten carbide-based cemented carbide comprising 15 to 40% by weight of a metallic binder phase. Wherein the weldable layer (1b) is directly sinter-bonded or integrally sinter-bonded via an intermediate layer (1c) made of a mixture thereof. 2. A weldable layer (1b) of a tungsten carbide-based cemented carbide having a metallic binder phase content of 15 to 40% by weight bonded directly or via an intermediate layer (1c) and alumina, zirconia, Wear-resistant layer (1) of a ceramic sintered body made of at least one of silicon carbide and silicon nitride
a) A method for producing a ceramic-carbide composite sintered body comprising a) by a current sintering method using a molded outer frame (2) and upper and lower punches (3, 4). Weldable layer material powder (1b) from wear layer material powder (1a1) side
The jig (5) increases continuously and / or stepwise toward the 1) side so that the end face of the lower punch (4) on the side of the powdery material (1b1) of the weldable layer coincides with the end face of the outer frame (2). By disposing the molded outer frame (2) as at least one energizing path, a temperature gradient is formed in the pressing axis direction of the ceramic-carbide sintered raw material powder (11) during energization. A method for producing a ceramic-ultrahard composite sintered body, comprising sintering a ceramic-ultrahard sintered raw material powder (11).