JP2005220015A - High-strength, high-anti-wear diamond sintered compact, tool made of the same and method for cutting non-ferrous metal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diamond sintered compact which is excellent in resistance to wear, chipping resistance, impact resistance and thermal conductivity. <P>SOLUTION: The diamond sintered compact contains a sintered diamond particle and the balance being a sintering aid, wherein the sintered diamond particle content is 80 vol.% or higher but smaller than 99 vol.% and the particle size of the sintered diamond particle is within the range of 0.1-70 μm. Adjacent sintered diamond particles are directly bound to each other. The sintering aid contains tungsten and at least one chosen from the group consisting of iron, cobalt and nickel. The proportion of tungsten in the sintered compact is 0.01-8 wt.%. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a high-strength, high-abrasion resistant diamond sintered body, and in particular, excellent in wear resistance, fracture resistance, impact resistance, and thermal conductivity, and is represented by cutting tools such as turning tools, milling tools, and end mills. The present invention relates to wear resistant tools represented by tools, wire drawing dies and the like, impact resistant parts represented by golf club heads and jigs for impact type powder crushing.

  Diamond has the highest hardness among the substances existing on the ground. Among them, the diamond sintered body is particularly used as a raw material for a cutting tool made of a non-ferrous metal material such as an aluminum-silicon alloy because it is difficult to cause a defect due to cleavage, which is a defect of single crystal diamond. As this diamond sintered body, for example, Japanese Examined Patent Publication No. 39-20483 (Patent Document 1) and Japanese Examined Patent Publication No. 52-12126 (Patent Document 2) use diamond-based metal binding materials such as cobalt. A sintered product is disclosed.

  Among these diamond sintered bodies, diamond particles having a particle size of less than 5 μm, and particularly ultrafine particles having a particle size of 1 μm or less are known to have excellent fracture resistance. Yes. For example, Japanese Examined Patent Publication No. S39-20483 discloses a diamond sintered body composed of fine diamond powder and a powder of iron-based metal or the like that dissolves and reprecipitates diamond, and Japanese Patent Publication No. 58-32224 discloses a particle size. Discloses a diamond sintered body comprising sintered diamond particles having a particle size of 1 μm or less, carbides, nitrides, borides, and solid solutions or mixtures thereof of the periodic table 4a, 5a or 6a metal and an iron-based alloy.

  When these fine diamond particles and an iron group metal such as cobalt or tungsten carbide-cobalt are used as starting materials, since the fine diamond particles are very active, the sintering temperature is high. If the pressure conditions are not strictly controlled, abnormal grain growth of the diamond grains frequently occurs. Therefore, the diameter of some diamond particles becomes very large, and it is difficult to obtain a diamond sintered body having a uniform structure with a particle diameter of 1 μm or less with good yield.

  In order to solve this problem, a method for controlling grain growth by arranging hard particles such as tungsten carbide, cubic boron nitride, silicon carbide, etc. having hardness close to diamond at the grain boundaries of diamond is known. It has been. For example, Japanese Patent Publication No. 61-58432 (Patent Document 3) discloses a diamond sintered body to which tungsten carbide as hard particles is added.

  However, this method controls abnormal grain growth of diamond particles by placing hard particles with low affinity with diamond particles between the diamond particles and physically and chemically preventing direct bonding between diamond particles. Therefore, skeleton formation by fusion of diamond particles becomes insufficient. Therefore, there is a problem that the fracture resistance, impact resistance and thermal conductivity, which are the original characteristics of diamond, are lowered.

  On the other hand, among the diamond sintered bodies, those having a coarse particle diameter of diamond particles of 5 μm or more and 100 μm or less are generally known to have excellent wear resistance. However, since coarse diamond particles are difficult to sinter, a method of forming carbide on the surface of diamond particles is known in order to facilitate sintering. For example, in Japanese Patent Laid-Open No. 63-134565 (Patent Document 4), carbides are generated on the surface of diamond particles to enhance the bonding strength of the sintering aid metal to the individual diamond particles, making it easy to sinter. Is disclosed. In order to facilitate sintering, many products obtained by adding tungsten carbide to a sintering aid have been commercialized.

However, when carbide is generated on the surface of diamond particles, the wear resistance, fracture resistance, impact resistance, and thermal conductivity are reduced as compared with a diamond sintered body composed only of diamond particles and an iron-based metal. There is a problem. Moreover, if tungsten carbide is added to the sintering aid, the sintering aid component increases, and there is a problem that the wear resistance of the diamond sintered body is likely to be lowered.
Japanese Patent Publication No. 39-20483 Japanese Examined Patent Publication No. 52-12126 Japanese Examined Patent Publication No. 61-58432 JP-A 63-134565

  In recent years, in cutting using a diamond sintered body, the number of materials having high hardness and difficult to cut is increasing. For this reason, wear resistance, chipping resistance, impact resistance and thermal conductivity which are higher than those of conventional ones are required.

  Therefore, the present invention has been made to solve the above-mentioned problems, and diamond sintering superior in wear resistance, fracture resistance, impact resistance and thermal conductivity than conventional diamond sintered bodies. The purpose is to provide a body.

  As a result of sincerity studies to improve the fracture resistance, wear resistance, etc. of the diamond sintered body, the present inventors have made the direct bonding between diamond particles stronger, It has been found that strength such as fracture resistance and impact resistance, wear resistance and thermal conductivity can be improved. Therefore, conventionally, in a sintered body using fine diamond powder, hard particles having low affinity with diamond particles have been used to suppress the growth of diamond particles, but without using these hard particles, The method of suppressing growth was examined.

  As a result, during sintering, diamond dissolves in the iron-based metal as a sintering aid, and when the sintering is completed and the diamond sintered body is cooled, the diamond in the iron-based metal reprecipitates. It was found that abnormal growth of diamond particles occurred. In order to prevent this, by adding metallic tungsten to the iron-based metal as a sintering aid, the amount of diamond dissolved in the iron-based metal is reduced. Growth can be prevented. Thereby, since it is not necessary to use the conventional hard particle | grains, it becomes easy to fuse | melt diamond particles and a firm frame | skeleton is formed. Moreover, since it is not necessary to add hard particles, the content of diamond in the diamond sintered body increases.

  Further, in a sintered body using coarse diamond powder, diamond particles are easily sintered by metallic tungsten added in the sintering aid. Therefore, the conventional addition of tungsten carbide becomes unnecessary, and the wear resistance of the diamond sintered body can be improved.

  Moreover, it discovered that the abrasion resistance of a sintered compact increased, so that the content of the diamond particle in a diamond sintered compact was large.

  Moreover, it discovered that the magnitude | size of the defect in a sintered compact and intensity | strength, such as a fracture resistance of a sintered compact, impact resistance, had a close relationship. The defect mentioned here means a diamond particle having a remarkably large diameter in the diamond sintered body, a pool of sintering aids such as a solvent metal, voids and the like. The smaller the defects in the diamond sintered body, the higher the strength of the sintered body.

  The high-strength and high-abrasion resistant diamond sintered body of the present invention made based on these findings includes sintered diamond particles, and the balance includes a sintering aid and inevitable impurities. The content of sintered diamond particles is 80% by volume or more and less than 99% by volume. Sintered diamond particles have a particle size in the range of 0.1 μm to 70 μm. Adjacent sintered diamond particles are directly bonded to each other. The sintering aid includes metallic tungsten and at least one selected from the group consisting of iron, cobalt and nickel. In this specification, “tungsten” refers to a mixture of tungsten in a metal form and a tungsten compound such as tungsten carbide. The content of tungsten in the sintered body is 0.01% by weight or more and 8% by weight or less.

  In such a diamond sintered body, metallic tungsten is added to the sintering aid. Therefore, even when the diameter of diamond particles used as a raw material is small, abnormal growth of the particles can be suppressed without adding hard particles. In addition, even when the diameter of diamond particles used as a raw material is increased, by adding tungsten in the form of metal to the sintering aid, high resistance to fracture, wear resistance, impact resistance and thermal conductivity is achieved. A diamond sintered body with high strength and high wear resistance can be obtained. Further, since the amount of the sintering aid added is not larger than that of the conventional one, and the diamond content is not smaller than the conventional amount, the wear resistance and the like are not deteriorated.

  The reason why the content of the sintered diamond particles is 80% by volume or more and less than 99% by volume is as follows. This is because when the content of sintered diamond particles is less than 80% by volume, strength such as fracture resistance and impact resistance and wear resistance are lowered, and the content of diamond particles is 99% by volume or more. This is technically difficult.

  The reason why the range of the particle diameter of the sintered diamond particles is 0.1 μm or more and 70 μm or less is as follows. When the particle diameter of the sintered diamond particles is less than 0.1 μm, the surface area of the diamond particles increases, so that abnormal growth of the diamond sintered body is likely to occur, and the wear resistance of the diamond sintered body decreases. is there. This is because if the particle size exceeds 70 μm, the strength of the diamond sintered body decreases due to cleavage of the diamond particles.

  The reason why the content of tungsten in the sintered body is 0.01 wt% or more and 8 wt% or less is as follows. This is because if the tungsten content is less than 0.01% by weight, the effect of adding metallic tungsten to the sintering aid cannot be obtained. If the tungsten content exceeds 8% by weight, the content of diamond in the sintered body decreases, and the solid solution of diamond in the sintering aid becomes too small, so that sintering is completely performed. Because it disappears.

The diamond sintered body contains tungsten carbide, and the X-ray diffraction intensity I _WC by the (100) face or the (101) face of tungsten carbide in the diamond sintered body and the X-ray diffraction by the (111) face of the sintered diamond particles. The ratio of intensity I _D (I _WC / I _D ) is less than 0.02, and the diamond sintered body contains cobalt, and the ratio of X-ray diffraction intensity I _CO and I _D by (200) plane of cobalt (I _CO / _ID ) is preferably less than 0.4.

The diamond sintered body contains nickel, and the ratio of the X-ray diffraction intensity I _Ni by the (200) plane of nickel in the diamond sintered body to the X-ray diffraction intensity I _D by the (111) plane of sintered diamond particles ( I _Ni / _ID ) is preferably less than 0.4.

The diamond sintered body contains iron, and the ratio of the X-ray diffraction intensity I _Fe by the (200) plane of iron in the diamond sintered body to the X-ray diffraction intensity I _D by the (111) plane of sintered diamond particles ( I _Fe / I _D ) is preferably less than 0.2. Here, “X-ray diffraction intensity” refers to the height of a peak in an X-ray diffraction pattern using CuKα rays (characteristic X-rays generated by the K shell of Cu).

The reason why it is defined in this way is that I _WC / _ID is less than 0.02 because if it exceeds 0.02, the amount of tungsten carbide becomes excessive and the wear resistance decreases. In addition, when the intensity ratio of each diffraction line of the iron-based metal exceeds the above range, the amount of iron-based metal in the diamond sintered body becomes excessive, and the wear resistance of the diamond sintered body decreases. It is.

  Further, the sintering aid further contains palladium, and the proportion of palladium in the sintering aid is preferably 0.005 wt% or more and 40 wt% or less. In this case, since palladium is added to the sintering aid, the diamond sintered body can be produced at a low temperature by lowering the melting point of the sintering aid. The reason why the ratio of palladium is set to 0.005 wt% or more and 40 wt% or less is as follows. If the proportion of palladium is less than 0.005% by weight, it is not sufficient to lower the melting point of the sintering aid. If the proportion of palladium exceeds 40% by weight, the melting point of the sintering aid is reversed. This is because the sinterability deteriorates due to the increase.

  The sintering aid further includes at least one selected from the group consisting of tin, phosphorus and boron, and the total proportion of tin, phosphorus and boron in the sintering aid is 0.01% by weight or more. It is preferable that it is 30 weight% or less. In this case, since the sintering aid contains at least one of tin, phosphorus and boron, these elements lower the melting point of the sintering aid. As a result, diamond powder can be sintered at a relatively low temperature. Here, the reason why the ratio of these elements is 0.01 wt% or more and 30 wt% or less is as follows. If the ratio of these elements is less than 0.01% by weight, the effect of lowering the melting point of the sintering aid is not sufficient, and if it exceeds 30% by weight, the iron-based metal in the sintering aid is reduced during sintering. Diamond hardly dissolves. This is because the diamond particles are not reliably bonded to each other, and the strength and thermal conductivity are lowered.

  In addition, the present inventors pay attention to oxygen and oxide adsorbed on the surface of diamond powder as a raw material for producing a diamond sintered body, and by removing these, defects existing in the sintered body are reduced. The inventors have found that the strength of the diamond sintered body is improved. Therefore, the proportion of oxygen in the diamond sintered body is preferably 0.005 wt% or more and less than 0.08 wt%. The oxygen ratio of 0.005 wt% or more and less than 0.08 wt% is impossible with the current technology, and if it is 0.08 wt% or more, diamond This is because the strength of the sintered body is the same as the conventional one.

The bending strength measured under the condition of a span of 4 mm using a measurement specimen having a length of 6 mm, a width of 3 mm, and a thickness of 0.35 mm to 0.45 mm produced from the diamond sintered body thus obtained is it is preferably 50 kgf / mm ² or more 300 kgf / mm ² or less.

Moreover, it is preferable that the bending strength measured on the conditions of 4 mm span using the test piece which consists of the diamond sintered compact obtained in this way, and which was melt-processed with hydrofluoric acid is 50 kgf / mm < ² > or more.

  Furthermore, it is preferable to use the above-mentioned diamond sintered body as a tool.

  In order to obtain a diamond sintered body in the present invention, it is preferable to uniformly distribute the sintering aid and not to include unnecessary components. Considering this point, as a method of coating each particle of diamond powder with a sintering aid, a CVD (Chemical Vapor Deposition) method, a PVD (Physical Vapor Deposition) method or a solution precipitation method can be used.

  In the diamond sintered body of the present invention, the uniformity of the sintering aid coated on the surface of the diamond particles is extremely important for improving the sinterability of the diamond powder and the strength of the sintered body. In view of the fact that the method must be excellent in performance, it is most preferable to use the electroless plating method disclosed in Japanese Patent Laid-Open No. 8-225875 by the inventors.

  The high-strength and high-abrasion resistant diamond sintered body of the present invention contains sintered diamond particles, and the balance includes a sintering aid and inevitable impurities. The content of sintered diamond particles is 80% by volume or more and less than 99% by volume. Sintered diamond particles have a particle size in the range of 0.1 μm to 70 μm. Adjacent sintered diamond particles are directly bonded to each other. The sintering aid includes at least one selected from the group consisting of tungsten in the form of metal and iron and cobalt. The content rate of tungsten in a sintered compact is 0.01 to 8 weight%. The proportion of oxygen in the diamond sintered body is 0.005 wt% or more and less than 0.08 wt%. It is obtained by sintering diamond powder having a particle size of 0.1 μm or more and 4 μm or less.

  Preferably, the high-strength and high wear-resistant diamond sintered body is manufactured by sintering diamond particles that have been heat-treated at a temperature of 1100 ° C. or higher and 1400 ° C. or lower. More preferably, the heat treatment temperature is 1200 ° C. or higher and lower than 1400 ° C.

  A tool according to the present invention is a tool composed of a high-strength, high-abrasion-resistant diamond sintered body, comprising sintered diamond particles, and the balance of a sintering aid and inevitable impurities, The content is 80% by volume or more and less than 99% by volume, the sintered diamond particles have a particle size in the range of 0.1 μm or more and 70 μm or less, and the adjacent sintered diamond particles are directly bonded to each other and sintered. The binder includes metallic tungsten and at least one selected from the group consisting of iron and cobalt, and the content of tungsten in the sintered body is 0.01 wt% or more and 8 wt% or less. Yes, the proportion of oxygen in the diamond sintered body is 0.005 wt% or more and less than 0.08 wt%. The diamond sintered body is exposed to form a flank.

  The nonferrous metal cutting method according to the present invention uses the above tool.

  As described above, according to the present invention, by adding tungsten, the skeleton is sufficiently formed by fusion of diamond particles, and components other than the sintering aid are eliminated as much as possible in the sintered body. By improving the diamond content, it is possible to provide a diamond sintered body that is more excellent in wear resistance, fracture resistance, impact resistance and thermal conductivity than conventional tools.

  Examples of the present invention will be described below.

(Example 1)
Production of Diamond Sintered Body Diamond powders having different particle diameters shown in Table 1 and sintering aids (1A to 1H) having different components were prepared. For 1A, 1B, 1E and 1F, a sintering aid was added to the diamond powder by electroless plating, for 1C and 1G by ultrafine powder mixing, and for 1D and 1H by a carbide ball mill. For ultrafine powder mixing, ultrafine cobalt powder with a particle size of 0.5 μm or less and diamond powder are put into a Teflon (registered trademark) ball mill container so as to have a predetermined composition, and further, Teflon (registered trademark) is added. A powder sample was prepared by placing a ball made in a container and ball milling for 3 hours. Regarding the carbide ball mill, diamond powder, tungsten carbide powder and cobalt powder were put into a tungsten carbide-cobalt ball mill container together with tungsten carbide-cobalt balls and ball milled for a predetermined time. By controlling the time of the ball mill, a sample powder having a predetermined sintering aid composition was produced. Samples obtained by these techniques are shown in Table 1.

  In Table 1, “composition of sintering aid” refers to the proportion of each component in the sintering aid. For example, “90.85Co” indicates that 90.85 wt% of the sintering aid is cobalt.

  Samples 1A to 1D were then heat-treated at a temperature of 1300 ° C. for 60 minutes, and 1E to 1H were heat-treated at a temperature of 1500 ° C. for 60 minutes. Samples 1A to 1H were each placed in a tantalum container and sintered using a belt-type ultrahigh pressure generator under conditions of a pressure of 55 kilobars and a temperature of 1450 ° C. to obtain a diamond sintered body.

Evaluation of sintered diamond (Diffraction intensity ratio measurement)
For the diamond sintered body obtained in the above-described process, CuKα rays (characteristic X-rays generated by the K shell of Cu) are used, the acceleration voltage of the electron beam irradiated to the copper target is 40 kV, the current is 25 mA, the diffraction angle 2θ = 20. X-ray diffraction was performed under conditions of -80 ° and a scanning speed of 0.1 ° / sec. Thereby, the height (intensity) I _WC , I _D , and I _CO of each diffraction peak on the (101) plane of tungsten carbide, the (111) plane of diamond, and the (200) plane of cobalt was measured.
(Measurement of strength)
A plurality of rectangular parallelepiped test pieces having a length of 6 mm, a width of 3 mm, and a thickness of 0.4 mm were cut out from each diamond sintered body. For each sample, the strength (bending strength) of the sintered body was measured by a three-point bending test under a span distance of 4 mm. Further, each sample was put into a hydrofluoric acid solution in which 40 ml of nitric acid having a molar concentration of 30% and 10 ml of hydrofluoric acid having a molar concentration of 45% were mixed. Further, the sample was placed in a sealed container and kept at a temperature of 130 ° C. for 3 hours for dissolution treatment. For each of the sample subjected to the melting treatment and the sample not subjected to the melting treatment, the strength (bending strength) of the sintered body was measured by a three-point bending test under a span distance of 4 mm.
(Measurement of W content)
The total content of metallic tungsten (W) and tungsten carbide relative to the weight of the diamond sintered body was measured by plasma emission spectroscopy.
(Measurement of diamond content)
The diamond content of the sintered body was determined by observing the surface of the diamond sintered body with a microscope and measuring the diamond particle region.
(Evaluation of cutting performance)
A cutting tool was prepared from the sintered body, and the cutting performance was evaluated under the following conditions.

Work material: Al-16 wt% Si alloy round bar Rotational speed of work material surface: 700 m / min
Cutting depth: 0.5mm
Feeding speed: 0.15mm / rev
Cutting time: 5 min
(Confirmation of the presence of tungsten metal)
A transmission electron microscope observation sample was prepared from the obtained sintered body and observed in several arbitrary fields of view, and the presence or absence of metallic tungsten was confirmed from the electron diffraction pattern.

  These results are shown in Table 2.

  In Table 2, “W content” indicates the ratio of the weight of tungsten (total of metallic form tungsten and tungsten carbide) in the sintered body to the weight of the sintered body. In addition, the presence or absence of metallic tungsten confirmed by transmission electron microscope observation is indicated by ○ and × in the table.

  From Table 2, it can be seen that the strength and flank wear width of the products 1A and 1E of the present invention are good values.

  On the other hand, for 1C and 1D, since the amount of the sintering aid was small and this was unevenly distributed, melting of the sintering aid in the powder diamond did not occur uniformly, and a complete sintered body was obtained. Couldn't get.

  In addition, in the structure of the 1G sintered body, there are places where the sintering aid is unevenly distributed, so that the cutting edge of the tool is lost during cutting, and it can be used as a tool in the middle of cutting. It became impossible.

  Therefore, the products 1A and 1E of the present invention show higher strength and less flank wear width than the conventional products 1D and 1H, and also have high fracture resistance and are excellent as cutting tools. I understand that. As a result of microscopic observation, adjacent sintered diamond particles were directly bonded to each other.

(Example 2)
A test was conducted to compare the characteristics of the sintered bodies according to the particle size of the diamond particles. First, diamond powders with various particle sizes were prepared. A sintering aid was added by electroless plating so that the proportion of the diamond powder was 93% by volume and the proportion of the sintering aid having a predetermined composition was 7% by volume, followed by heat treatment. The diamond sintered compact was produced by the method. The strength and flank wear width of this diamond sintered body were measured in the same manner as in Example 1. The results are shown in Table 3.

  In 2A, a large amount of diamond was dissolved in the sintering aid, so the diamond content decreased. In 2C, the sintering aid flowed out, so the diamond content increased. From Table 3, it can be said that the smaller the particle diameter of the diamond powder, that is, the finer one (2A) is, the higher the strength is, and thus the superior impact resistance. Further, it can be seen that the larger the particle diameter, that is, the coarser one (2B) has a smaller flank wear width, and therefore the wear resistance is excellent. On the other hand, since the diamond particle diameter of 2C was too large, it was lost during cutting, and cutting could not be continued.

(Example 3)
A test was conducted on the characteristics of the sintered body according to the amount of metallic tungsten added in the sintering aid. First, diamond powder particles with various particle sizes were prepared. A sintering aid having a different tungsten ratio was added to the powder particles by an electroless plating method, followed by heat treatment, and sintered in the same manner as in Example 1 to obtain a diamond sintered body. The obtained diamond sintered body was measured for strength and flank wear width by the same method as in Example 1. Table 4 shows the obtained results.

  In Table 4, 3A and 3D are diamond sintered bodies produced from the same powder as Samples 1A and 1E produced in Example 1. Sample numbers 3B, 3C, 3E, and 3F are obtained by changing the amount of metallic tungsten added in the sintering aid.

  When the amount of tungsten in the sintered body exceeds 8% by weight as in Samples 3B and 3E, the strength or wear resistance decreases because the “strength” is small and the “flank wear width” is large. I understand. Moreover, about the samples 3C and 3F which did not add metallic tungsten, sintering was incomplete and it was not possible to obtain a sintered body stably. It can be seen that the strength and wear resistance of Samples 3A and 3D, in which the added amount of tungsten in the sintered body is 0.01% by weight or more and 8% by weight or less which is the range of the present invention, are excellent.

Example 4
The effect of the added amount of palladium in the sintering aid on sinterability was tested. First, diamond powder particles having different particle sizes were prepared. Next, a powder powder containing tungsten and palladium in various ratios, iron ratio of 4.0% by weight, tin ratio of 0.1% by weight and the balance of cobalt is applied to diamond powder. Formed. This raw material powder was held for 20 minutes under conditions of a pressure of 50 kilobars and a temperature of 1450 ° C. using a belt-type ultrahigh pressure generator. The results are shown in Table 5.

  In Table 5, “◯” indicates that the raw material powder was sintered and the particles did not become abnormally large. “Δ (grain growth)” indicates that although the diamond powder was sintered, some of the particles became abnormally large. “X” indicates that the diamond powder was not sintered. Moreover, about what added metallic tungsten, the analysis result of tungsten content in a sintered compact was shown in () in the table | surface. From Table 5, it can be seen that the sample containing only tungsten and the sample containing tungsten and palladium are surely sintered. Further, even when tungsten is not included, if palladium is included, sintering is performed to some extent. However, it is understood that when fine powder is used, sintering is not sufficiently performed. From this result, it is understood that when the palladium content, which is the range of the present invention, is in the range of 0.01 wt% to 40 wt%, sintering is likely to occur.

(Example 5)
Tests were performed on the properties of the sintered body with additional sintering aids. First, diamond powder particles having a particle size of 0.1 to 30 μm were prepared. In order to add a sintering aid to the diamond powder particles by electroless plating, the diamond powder was degreased and pickled. Next, diamond powder particles were immersed for 2 minutes in a room temperature solution containing palladium chloride, stannous chloride and hydrochloric acid as a pretreatment for electroless plating. Subsequently, these diamond powder particles were immersed in an aqueous sulfuric acid solution at room temperature for 2 minutes. Thereafter, this powder was washed with water and then immersed in an aqueous Ni—B plating solution containing nickel chloride and sodium boron hydroxide at a temperature of 90 ° C. for 2 minutes to obtain a diamond powder coated with a sintering aid.

  After forming these diamond powders by compression, a metal plate as an additional sintering aid having the composition shown in Table 6 and a molded body were laminated and sealed in a tantalum container.

  In Table 6, “additional sintering aid composition” indicates the composition of the metal plate. Further, the “coating amount of the sintering aid” indicates the volume% of the sintering aid in the diamond sintered body.

  Then, this tantalum container was held at a temperature of 1550 ° C. for 10 minutes at a pressure of 60 kilobars by a girdle type high pressure apparatus. Thereby, a diamond sintered body was obtained.

  Each of the sintered bodies was processed into a rod-shaped test piece having a length of 6 mm, a width of 3 mm, and a thickness of 0.3 mm, and then a three-point bending test with a span distance of 4 mm was performed to evaluate the strength. The results are shown in Table 7.

  As can be seen from Table 7, it can be seen that the strengths of 4B, 4C and 4D are improved as compared to 4A and 4E.

  That is, it can be seen that it is preferable if the total content of tin, phosphorus and boron in the sintering aid is in the range of 0.01 wt% to 30 wt%. Further, when a similar experiment was conducted with tin, phosphorus and boron contained in the sintering aid, it was found that the total content of these was preferably 0.01 wt% or more and 30 wt% or less.

(Example 6)
The characteristics of the diamond sintered body when the heat treatment temperature of the diamond powder was changed were tested. 1A and 1E produced in Example 1 were heat-treated under various conditions. Next, the heat-treated powder was sintered under the same conditions as in Example 1 to obtain a diamond sintered body. The strength of this diamond sintered body was measured by the same method as in Example 1, and the oxygen content in the sintered body was measured by plasma emission spectroscopic analysis. The results are shown in Table 8.

  In Table 8, 5A-1 to 5A-3 are those using the 1A powder of Example 1. In addition, 5E-1 to 5E-3 use 1E powder. From this result, it can be seen that increasing the heat treatment temperature tends to reduce the amount of oxygen remaining in the sintered body, and accordingly the strength of the sintered body increases.

  As a result of another experiment, regarding the powder sample 1A, when the heat treatment is performed at a high temperature of 1400 ° C. or higher, the surface of the diamond powder is remarkably graphitized, so that the graphite remains in the sintered body and is sintered and cut. It turned out to be unsuitable for reducing performance.

(Example 7)
A sample having a diamond particle size of 0.1 to 15 μm was prepared, and the same sintering aid as that added to the powder sample 1A of Example 1 was added, followed by heat treatment in a vacuum at a temperature of 1300 ° C. Next, the powder after the heat treatment is filled in a container made of a sintered body having an outer diameter of 20 mm, an inner diameter of 12 mm, and a height of 18 mm made of an alloy containing 10% by weight of tungsten carbide, and sintered under an ultrahigh pressure and high temperature condition. did. A drawing die having a wire diameter of 3 mm was produced from the obtained sintered body. Using this die, a copper-plated steel wire was drawn using a water-soluble lubricating oil at a drawing speed of 500 m / min. As a result, it was possible to draw an 80-ton steel wire, and the wire skin was also good.

(Example 8)
A circular throw-away tip having a diameter of 13.2 mm and a thickness of 3.2 mm was manufactured using the 1A and 1E diamond sintered bodies of Example 1, and a granite circle having a compressive strength of 1500 kg / cm ² under the following conditions. The bar was cut with a general-purpose lathe.

Work surface rotation speed: 180 m / min
Cutting depth: 0.5mm
Feeding speed: 0.25mm / rev
Cutting time: 3 minutes As a result, in the 1A diamond sintered body, no chipping was observed at the cutting edge, and the flank wear width exceeded 0.5 mm. On the other hand, with the 1E diamond sintered body, the flank wear width was as small as 0.1 mm although chipping of 0.03 mm occurred at the cutting edge, and cutting could be continued.

  Further, when cutting was performed with a conventional diamond sintered body tool, cutting resistance increased due to wear when cutting was performed for about 2 minutes, and abnormal noise was generated during cutting, making it impossible to continue cutting. When the used tool was observed, it was severely worn, and the cemented carbide supporting the diamond sintered body had cracked.

  Thus, when the diamond sintered body in the present invention was applied to a bit tool for excavation requiring impact resistance, excellent results were obtained.

Example 9
After applying a sintering aid containing various ratios of cobalt, tungsten, iron and palladium to diamond particles having a particle diameter of 0.1 to 60 μm by the same method as in Example 1 and heat-treating them. Sintered. Each of the obtained sintered bodies was subjected to X-ray diffraction in the same manner as in Example 1. The diffraction intensity I _Ni from the (200) plane of _nickel , the diffraction intensity I _{Fe from} the (200) plane of iron, ( The diffraction intensity I _D by the (111) plane was measured, and the ratios I _Ni / _ID and I _Fe / _ID were determined. For each sintered body, the strength and flank wear width were examined in the same manner as in Example 1.

As a result, those with I _Ni / _ID less than 0.4 or those with I _Fe / _ID less than 0.4 were excellent in both strength and flank wear width.

  It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

Claims (15)

Containing sintered diamond particles, and the balance of sintering aid and inevitable impurities,
The content of the sintered diamond particles is 80% by volume or more and less than 99% by volume,
The sintered diamond particles have a particle size in the range of 0.1 μm or more and 70 μm or less,
The adjacent sintered diamond particles are directly joined to each other,
The sintering aid includes metallic tungsten and at least one selected from the group consisting of iron, cobalt and nickel,
A high-strength and high-abrasion resistant diamond sintered body characterized in that the content of tungsten in the sintered body is 0.01 wt% or more and 8 wt% or less. The tungsten carbide further includes an X-ray diffraction intensity I _WC by the (100) plane or the (101) plane of the tungsten carbide and an X-ray diffraction intensity by the (111) plane of the sintered diamond particles. The ratio of I _D (I _WC / I _D ) is less than 0.02 and contains cobalt, and the ratio of the X-ray diffraction intensity I _CO by (200) plane of cobalt to I _D (I _CO / I The high-strength and high-abrasion resistant diamond sintered body according to claim 1, wherein _D ) is less than 0.4. The ratio of the X-ray diffraction intensity I _Ni due to the (200) plane of the nickel in the diamond sintered body and the X-ray diffraction intensity I _D due to the (111) plane of the sintered diamond particle (I _Ni / I) The high-strength and high-abrasion resistant diamond sintered body according to claim 1 or 2, wherein _D ) is less than 0.4. The ratio of the X-ray diffraction intensity I _{Fe from} the (200) plane of the iron in the diamond sintered body to the X-ray diffraction intensity I _{D from} the (111) plane of the sintered diamond particle (I _Fe / I) The high-strength and high-abrasion resistant diamond sintered body according to any one of claims 1 to 3, wherein _D ) is less than 0.2.   The sintering aid according to claim 1, wherein the sintering aid further includes palladium, and the ratio of the palladium in the sintering aid is 0.005 wt% or more and 40 wt% or less. The high strength and high wear resistant diamond sintered body according to any one of the above items.   The sintering aid further includes at least one selected from the group consisting of tin, phosphorus and boron, and a total ratio of the tin, phosphorus and boron in the sintering aid is 0.01% by weight or more. The high-strength and high-abrasion resistant diamond sintered body according to any one of claims 1 to 5, wherein the sintered body is 30% by weight or less.   The high strength and high wear resistance according to any one of claims 1 to 6, wherein a ratio of oxygen in the diamond sintered body is 0.005 wt% or more and less than 0.08 wt%. Sintered diamond. The strength (bending force) of the diamond sintered body measured under the condition of a span of 4 mm using a measurement specimen having a length of 6 mm, a width of 3 mm, and a thickness of 0.35 mm to 0.45 mm is 50 kgf / mm ^2. The high-strength / high-abrasion resistant diamond sintered body according to any one of claims 1 to 7, wherein the sintered body has a strength of 300 kgf / mm ² or less. 9. The strength (bending strength) of the diamond sintered body measured at 4 mm span using the test piece dissolved in hydrofluoric acid is 50 kgf / mm ² or more. A high-strength, high-abrasion resistant diamond sintered body described in 1.   A tool comprising the high-strength, high-abrasion resistant diamond sintered body according to any one of claims 1 to 9. Containing sintered diamond particles, and the balance of sintering aid and inevitable impurities,
The content of the sintered diamond particles is 80% by volume or more and less than 99% by volume,
The sintered diamond particles have a particle size in the range of 0.1 μm or more and 70 μm or less,
The adjacent sintered diamond particles are directly joined to each other,
The sintering aid includes metallic form tungsten and at least one selected from the group consisting of iron and cobalt,
The tungsten content in the sintered body is 0.01 wt% or more and 8 wt% or less,
The proportion of oxygen in the diamond sintered body is 0.005 wt% or more and less than 0.08 wt%,
A high-strength, high-abrasion resistant diamond sintered body obtained by sintering diamond powder having a particle size of 0.1 μm or more and 4 μm or less.   The high-strength and high-abrasion-resistant diamond sintered body according to claim 11, which is produced by sintering diamond particles preliminarily heat-treated at a temperature of 1100 ° C or higher and lower than 1400 ° C.   The high-strength and high-abrasion resistant diamond sintered body according to claim 12, wherein the heat treatment temperature is 1200 ° C or higher and lower than 1400 ° C. Containing sintered diamond particles, and the balance of sintering aid and inevitable impurities,
The content of the sintered diamond particles is 80% by volume or more and less than 99% by volume,
The sintered diamond particles have a particle size in the range of 0.1 μm or more and 70 μm or less,
The adjacent sintered diamond particles are directly joined to each other,
The sintering aid includes metallic form tungsten and at least one selected from the group consisting of iron and cobalt,
The tungsten content in the sintered body is 0.01 wt% or more and 8 wt% or less,
A tool comprising a high-strength and high-abrasion-resistant diamond sintered body, wherein the proportion of oxygen in the diamond sintered body is 0.005 wt% or more and less than 0.08 wt%, A tool that is exposed and forms a flank.   A nonferrous metal cutting method using the tool according to claim 14.