JPS6319585B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a diamond sintered body used in various tools such as cutting tools, drilling tools, and wire drawing dies. [Prior Art] Currently, sintered bodies for tools with a diamond content of 70% by volume or more and diamond particles bonded to each other are on sale. These sintered bodies are used for cutting nonferrous metals, plastics, or ceramics, and as dressers, drill bits, or wire drawing dies. In particular, when these diamond sintered bodies are used as dies for cutting non-ferrous metals or drawing relatively soft wire materials such as copper wires, their performance is extremely excellent. These diamond sintered bodies are usually sintered using an iron group metal such as Co, which is a catalyst during diamond synthesis, as a binder.
Diamond has the disadvantage that it turns into graphite and deteriorates when heated to a temperature of 600°C or higher. In order to improve the heat resistance of this diamond sintered body, it is possible to remove iron group metals such as Co, which promote graphitization of diamond during heating, as described in JP-A-53-114589. . However, when iron group metals such as Co are leached from the diamond sintered body, the strength of the diamond sintered body decreases by approximately 20 to 30%. In particular, when diamond sintered bodies are used for bit applications, strength, wear resistance, and heat resistance are required.
The drill bit using a diamond sintered body described in No. 114589 had the drawback that the cutting edge was damaged due to the lack of strength of the diamond sintered body, resulting in a shortened lifespan. The inventors of the present application previously proposed a diamond sintered body having excellent strength, good wear resistance, and further excellent heat resistance in JP-A No. 59-35066. This sintered body uses carbides from Groups 4a, 5a, and 6a of the periodic table as a binder to substantially reduce the pore content, thereby suppressing the decrease in strength of the sintered body due to Co elution. That is. [Problems to be Solved by the Invention] However, although the diamond sintered body disclosed in JP-A No. 59-35066 does not have much strength loss, at high temperatures exceeding 1000°C, the carbide and diamond deteriorate. It was found that deterioration occurs due to differences in thermal expansion. Therefore, it has not yet been fully satisfactory in applications where the cutting edge is exposed to high temperatures, such as geothermal well drilling. Therefore, an object of the present invention is to provide a diamond sintered body for tools that has further excellent heat resistance, strength, and wear resistance. [Means and effects for solving the problem] The inventors of the present application have conducted extensive research in order to obtain a diamond sintered body with even higher heat resistance. As a result, the diamond content exceeds 93% by volume, % by volume or less, and the remainder is 4a, 5a, 6a of the periodic table
group metals or carbides and/or iron group metals
A diamond sintered body consisting of 0.1 to 3% by volume, 0.5% to 7% by volume of pores, or containing 0.005 to 0.25% by volume of boron and/or boride has further improved heat resistance. It was discovered that it has excellent wear resistance and strength. In order to improve the heat resistance of the diamond sintered body, the iron group metal serving as the binder may be removed as described above. However, the locations where the binder was present become voids due to the removal of the iron group metal. By the way, in a diamond sintered body, the relationship shown in FIG. 1 exists between its strength and pores. In other words, as the number of pores increases, the strength of the diamond sintered body decreases, but when the number of vacancies exceeds 3%, the strength begins to decrease, and between 4.5% and 8%, a sharp decrease in strength occurs, and when the number of vacancies exceeds 8%, the strength decreases. In this case, the rate of decrease in strength becomes smaller. Generally, the strength required for a diamond sintered body differs depending on its use, the strength of the workpiece, etc. For example, commercially available heat-resistant sintered diamonds can be used for drilling relatively soft rocks or cutting ceramics.
If it is 1.5 times stronger, its performance will be significantly improved. Therefore, for such uses, the sintered body must have a pore content of at least 7% or less and a diamond content of 93% by volume or more. If the pore content is less than 5% by volume, the strength of the diamond sintered body will be approximately three times that of commercially available heat-resistant diamond sintered bodies, making it suitable for drilling hard rocks and cutting high-hardness materials and ceramics. Shows excellent performance and is desirable. The method for manufacturing the diamond sintered body of this invention involves heating raw diamond powder at a high temperature of 1300°C or higher to graphitize the surface of the diamond powder, and using a mixture of diamond powders with different particle sizes as the raw material. It is said that this makes it possible to obtain a dense sintered body with a diamond content of over 93% by volume. However, when the diamond content exceeds 99% by volume, iron group metals become insufficient and a diamond sintered body with sufficient strength cannot be obtained. In the diamond sintered body of this invention, it is preferable that the content of pores be as small as possible, as shown in FIG. Metal is also required. Therefore, in this invention, a minimum of 0.5% by volume
There are vacancies. The diamond powder used in the production of the diamond sintered body of the present invention includes 40 to 60% by volume of diamond powder with an average maximum particle size of a, 30 to 40% by volume of diamond powder with a particle size of a/2, and the remainder with a particle size of a/2. A mixture at a ratio of 3 to a/1000 is preferable because a high diamond content can be obtained. The diamond sintered body of the present invention contains diamonds of various particle sizes, but when it does not contain metals or carbides of Groups 4a, 5a, and 6a of the periodic table, particularly fine diamond particles may be present. If an abnormal accumulation of iron group metal occurs in the vicinity and the metal is eluted, this part becomes a void. Therefore, if metal or carbide is contained, the strength will be further improved. This iron group metal and periodic table number
The content of metals or carbides of groups 4a, 5a, and 6a is
0.1 to 3% by volume is preferred. If this content exceeds 3% by volume, cracks will occur due to the difference in thermal expansion with diamond, and diamond will become graphitized, resulting in a decrease in heat resistance. In addition, it is preferable that this content be as low as possible, but since iron group metals remaining in the diamond raw material are practically impossible to elute, a minimum of 0.1% by volume of iron group metals, etc. will remain in the sintered body. Become. It has been found that the diamond sintered body of the present invention has excellent toughness, wear resistance, and heat resistance, especially when the carbide is WC or (Mo, W)C having the same crystal structure as WC. In addition, the sintered body of this invention has a capacity of 0.005~
When containing 0.25% boron and/or boride, the properties are further improved.
Generally, diamond particles are sintered under ultra-high pressure and high temperature by a diamond dissolution or precipitation phenomenon using a catalyst such as an iron group metal. When at least one of boron and borides is added, borides of iron group metals are formed, which lowers the melting point and increases the melt deposition rate, which causes the bonding parts between diamond particles (diamond skeleton parts) to grow. It can be inferred that the holding power of the diamond particles was improved.
When the boron or boride content is less than 0.005%, the formation of the diamond skeleton is slow. On the other hand, the content of boron or boride is 0.25%
If the value exceeds 1, a large amount of boron will enter the diamond skeleton, and the strength of the diamond skeleton will decrease. The diamond powder used in the diamond sintered body of the present invention can be either synthetic diamond or natural diamond. In the method for producing a diamond sintered body of the present invention, metals or carbides of Groups 4a, 5a, and 6a of the periodic table are mixed with metals and powders of iron group metals such as Fe, Co, and Ni, or boron or borides are added thereto. The powders are mixed uniformly using a ball mill or other means. The iron group metal may be infiltrated by contacting the member made of the iron group metal during sintering without being mixed in advance. In addition, the inventors' earlier application (Japanese Patent Application No. 52-51881)
4a, 5a, 5a,
A sintered body of group 6a carbide and iron group metal is prepared, and at the same time diamond powder is ground in a ball mill, the pot and ball are used to form a sintered body of 4a of the periodic table.
A method of mixing fine powder of a sintered body of carbides of groups 5a and 6a and iron group metals may also be adopted. The mixed powder is heated to a high temperature of over 1,300°C to partially graphitize the diamond, and then placed in an ultra-high pressure and high temperature device to sinter under conditions where the diamond is stable. It is necessary to sinter at a temperature higher than the temperature at which a eutectic liquid phase appears between the iron group metal used at this time and a compound such as a carbide. The diamond sintered body thus produced is placed in an acid capable of corroding iron group metals, such as aqua regia, to elute iron group metals and form pores. Applications of the diamond sintered body of the present invention include wire drawing dies, ceramic cutting tools, dressers, etc. in addition to bits. [Example] Hereinafter, the present invention will be specifically explained using examples. Example 1 Average particle size 100μm, 50μm, 20μm and 5~
Diamond powder of 0.2 μm was mixed in a ratio of 5:3:1:1, and then ground and mixed for 5 minutes using a pot and ball made of WC-Co cemented carbide. After heating this powder at a temperature of 1400℃ for 30 minutes in a vacuum, it is filled into a Mo container, a Co plate is placed on top of the finished powder, and brought into contact with it, using an ultra-high pressure and high temperature device.
First, a pressure of 55 kb was applied, followed by heating to a temperature of 1460°C and holding for 10 minutes. The sintered body thus obtained was taken out from the container and the content of diamond, WC and Co was measured by chemical analysis, and the contents were 96.5% by volume, 0.15% by volume, and 3.35% by volume, respectively.
It was % by volume. Next, this sintered body was placed in heated aqua regia to elute the Co, and the composition was investigated using a magnetic balance and chemical analysis, and it was found that diamond was 96.5% by volume and WC was 0.14%.
% by volume, Co was 0.4% by volume, and pores were 2.96% by volume.
When we measured the compressive strength of this sample, it was 380Kg/
It showed the strength of mm ² . For comparison, the maximum diamond grain size is the same, the diamond content is 92.0% by volume, and the void
A sample containing 7.7% by volume and 0.3% by volume of Co was produced and its compressive strength was measured and found to be 120Kg/mm ² . Next, in order to test the heat resistance of the sintered body of the present invention, it was heated to 1200°C in vacuum and held for 30 minutes, and no dimensional changes or cracks occurred at all. Example 2 Diamond particles with average particle sizes of 80 μm, 40 μm, 15 μm and 0.5 μm were blended in a ratio of 5:3:2:1. This powder was mixed with various iron group metals shown in Table 1 and metals or carbides of groups 4a, 5a, and 6a of the periodic table, and the powder was filled into a Ta container. Similarly, 58kb,
Sintering was performed at 1500℃. Each of the sintered bodies thus obtained was taken out of the Ta container and treated in heated aqua regia. Next, the pore content of the sintered body was measured. The results are also shown in Table 1. After that, these diamond sintered bodies were cut into cubes with sides of 3 mm, and a high melting point, high hardness matrix made of a mixed powder of W, WC, Fe, Co, Ni, and Cu was used for the steel body. 1100
It was sintered and fixed at a temperature of °C to create the core bit of Surf Esset. For comparison, COREBIT (indicated by symbol (indicated by symbol Y in Table 1) was created. Uniaxial compressive strength of 1600 to 2000 for samples A to L, X and Y shown in Table 1 above, respectively.
Kg/cm ² granite was drilled at 900 revolutions. The digging speed and life are shown in Table 2.

[Table] *3: Pore volume after acid treatment

【table】

[Table] Example 3 Diamond powder with an average particle size of 0.8 μm and boron powder were ground and mixed using a WC-Co cemented carbide bottle and ball. This powder and average particle size
60μm, 30μm and 10μm diamond powders are mixed in a ratio of 1:5:3:1, and then
It was heated in vacuum at a temperature of 1450°C for 1 hour, and sintered at 55 kb and 1450°C in the same manner as in Example 1. Analysis of this sintered body revealed that diamond was 96.2% by volume, Co was 3.45% by volume, Ni was 0.1% by volume,
It was confirmed that the sintered body was composed of 0.2% by volume of WC and 0.5% by volume of boron. When this sintered body was treated in heated aqua regia, 3.3% by volume of pores were generated. Using this sintered body, alumina ceramics with a Vickers hardness of 2300 was cut for 15 minutes using water-soluble cutting oil at a cutting speed of 60 m/min, depth of cut: 0.3 mm, and feed: 0.05 mm/rotation. For comparison, commercially available heat-resistant diamond with a particle size of 40 μm to 60 μm and 8% by volume of pores was used for cutting. As a result, the flank wear width of the sintered body of this invention is
In contrast, the flank wear width of commercially available heat-resistant diamond was 0.58 mm. Example 4 The maximum particle size was changed by changing the blending ratio of diamond particles with different particle sizes and the graphitization treatment conditions.
Various diamond sintered bodies having a diameter of 60 μm and different diamond contents were prepared in the same manner as in Example 3, and then subjected to acid treatment to prepare heat-resistant diamond sintered bodies. Table 3 shows the diamond and pore contents of each sintered body.

[Table] Each sintered body M...R shown in Table 3 was processed as a chip for cutting, and the compressive strength was 1000~
Cutting speed: 200m/min for andesite of 1100Kg/ ^cm2 .
Wet cutting was performed for 20 minutes at a depth of cut of 1 mm and a feed rate of 0.3 mm/rotation, and the flank wear width was measured. The results are shown in Table 2. As is clear from Figure 2, the flank wear width of samples M, N, O, and P, in which the pore volume is 7% by volume or less, is greater than that of samples Q, R, in which the pores are 7% by volume or more. It turns out that there are far fewer. Example 5 Diamond powders with average particle sizes of 50 μm, 25 μm, 10 μm and 0.5 μm were mixed in a ratio of 55:30:10:5. This diamond powder and No. 4a, 5a, 6a
After compounding and mixing the group transition elements in the proportions shown in Table 4, the mixture was heated in vacuum at 1500° C. for 30 minutes to obtain a finished powder. This finished powder was treated with Mo in the same manner as in Example 1.
After filling the powder into a manufactured container, a Co plate was placed on top of the finished powder and sintered at a pressure of 50 kb and a temperature of 1500°C for 15 minutes. Table 5 shows the results of analysis of these sintered diamonds after they were taken out of the Mo container and the results of analysis after placing them in aqua regia for 100 hours to elute the metal. Next, using the sintered diamond treated with aqua regia, an alumina round bar with a Bitkers hardness of 2300 was cut at a cutting speed of 80 m/min, depth of cut of 0.2 mm, and feed of 0.1 mm/rotation.
Cut for 30 minutes. The flank wear width at this time is also 5th.
Shown in the table.

【table】

【table】

[Table] Example 6 0.7 μm diamond powder and boron powder were blended in the proportions shown in Table 6. These powders were mixed for 30 minutes using a cemented carbide pot and ball, and this powder and diamond powder with particle sizes of 50 μm, 25 μm, and 6 μm were mixed in a ratio of 5:50:30:15, and then 1600 ℃ for 10 minutes in a vacuum of 10 ⁻⁵ torr. Next, these finished powders were sintered in the same manner as in Example 1, and then the container was removed. These sintered bodies were placed in aqua regia for 150 hours to elute the metal, and the results of subsequent analysis are shown in Table 6. Using these sintered diamonds, a pressureless sintered silicon nitride round bar with a Bitkers hardness of 1700 was cut at a cutting speed of 100 m/min.
Dry cutting was performed for 20 minutes with a depth of cut of 0.2 mm and a feed rate of 0.3 mm/rotation. The results are also shown in Table 6.

[Table] [Effects of the Invention] As described above, according to the present invention, it is possible to obtain a diamond sintered body for tools with further improved heat resistance, strength, and wear resistance.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between compressive strength and pore volume in a heat-resistant diamond sintered body from which the binder phase has been eluted. FIG. 2 is a diagram showing the results of an andesite cutting test on a heat-resistant diamond sintered body.

Claims (1)

[Claims] 1. The diamond content exceeds 93% by volume, and
99% by volume or less, and the remainder is from periodic table 4a, 5a,
1. A diamond sintered body for tools, characterized in that the total content of at least one of a group 6a metal or carbide and an iron group metal is 0.1 to 3% by volume, and vacancies are 0.5% to 7% by volume. 2 The diamond content exceeds 95% by volume and 99
% by volume or less, and the remaining pores are 0.5% by volume or more and less than 5% by volume, the diamond sintered body for tools according to claim 1. 3 Carbides of groups 4a, 5a, and 6a of the periodic table have the same crystal structure as WC or WC (MoW)C
A diamond sintered body for a tool according to claim 1 or 2. 4 Diamond content is more than 93% by volume and less than 99% by volume, and the remainder is from Periodic Table 4a, 5a, 6a
A total of 0.1 to 3% by volume of at least one of group metals or carbides and iron group metals, and 0.5% by volume of vacancies.
A diamond sintered body for a tool, characterized in that the total content of at least one of boron and boride is 0.005 to 0.25% by volume. 5 The diamond content exceeds 95% by volume,
The diamond sintered body for tools according to claim 4, wherein the pores are 99% by volume or less, and the remaining pores are 0.5% by volume or more and less than 5% by volume. 6 The carbides of groups 4a, 5a, and 6a of the periodic table are WC
or has the same crystal structure as WC (MoW)
The diamond sintered body for tools according to claim 4 or 5, which is C.