RU2347744C2 - Sintered diamond object with high strength and high wearing resistance and method of making it - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: present invention can be used in making a cutting and a machining tool and electrodes. The sintered diamond object with high strength and high wearing resistance contains 80-98 vol.% particles of sintered diamond, with average size of not more than 2 mcm, and a phase of binding substance, containing 50-99.5 wt % cobalt and 0.5-50 wt % of at least one element, chosen from a group comprising Ti, Zr, Hf, V, Nb, Ta, Cr, Mo. Part of the element or weight of the element is in form of carbide particles, with average size of not more than 0.8 mcm. The texture of carbide particles is non-continuous, and adjacent diamond particles are bonded together. Sintering is carried out at 5.7-7.5 GPa pressure and 1400-1900°C temperature in a "belt" type super-high pressure device.

EFFECT: provision of transverse breaking strength of not less than 2,65 GPa, excellent wearing resistance, resistance to shearing, shock resistance and thermal conductivity.

7 cl, 6 tbl, 5 dwg, 6 ex

Description

FIELD OF THE INVENTION

The present invention relates to a sintered diamond product with high strength and high wear resistance and to a method for its production, and more particularly to a cutting tool represented by turning tools, milling cutters and face mills, to a wear-resistant tool, for example, used to strengthen the fastening part or the sliding part in exhaust dies or in a tool for machining, and for use in electronic materials, such as electrode elements, which impart excellent wear resistance , Chipping resistance, impact resistance and thermal conductivity.

State of the art

Since diamond is the hardest substance among those on earth, a sintered diamond product is used in cutting tools or wear-resistant tools. For example, Japanese National Patent Publication No. 39-020483 (Patent Document 1) and Japanese National Patent Publication No. 52-012126 (Patent Document 2) describe a sintered diamond product obtained by sintering diamond particles with a binder consisting of an iron group metal, such as Co (cobalt). In a sintered diamond product, spalling due to cleavage, which is a disadvantage of single-crystal diamond, is less likely. For this reason, sintered diamond products are widely used as a starting material for a cutting tool or the like for cutting and processing metal material not containing iron, such as an Al (aluminum) - Si (silicon) alloy.

A sintered diamond product containing diamond particles having an average particle size of not less than 5 μm and not larger than 100 μm has excellent wear resistance. At the same time, a sintered diamond product containing finely divided diamond particles having an average particle size of less than 5 microns has excellent resistance to chipping.

As in the case of ordinary sintered ceramics, since the sintered diamond product contains diamond particles having a finer and more uniform particle size at a higher content (with a higher density), and the particles are more strongly bonded to each other, diamond particles are solid particles constituting the sintered diamond product and the sintered diamond product tend to exhibit higher resistance to chipping.

As a method for firmly bonding diamond particles, Patent Document 1 mentioned above describes a method using a binder containing a solvent, the solvent is an iron group metal such as Co, Fe (iron) or Ni (nickel) having a catalyst property, to dissolve the diamond powder and cause it to recrystallize, so as to form a direct bond, called neck growth, between the diamond particles in the powder. In addition, Japanese National Patent Publication No. 58-032224 (Japanese Patent Laid-Open No. 55-047363) (Patent Document 3) describes a method for bonding diamond particles by means of a binder consisting of a metal carbide of group 4a, 5a or 6a of the periodic table.

In a sintered diamond product obtained by the first method, generating neck growth between diamond particles using Co or a WC alloy (tungsten carbide) - Co, as a binder, unlike a sintered diamond product obtained by the latter method, particles diamonds can maintain a solid structure even after a binder, which is worse in hardness or corrosion resistance than a diamond particle, selectively wears due to mechanical wear, such as abrasion or chemical wear wear and tear, such as corrosion. For this reason, the sintered diamond product obtained by the first method is excellent in resistance to chipping and wear resistance.

The binder itself, consisting of Co or WC-Co alloy, in the first case has a hardness lower than the ceramic-type binder used in the latter method, not to mention a comparison with a diamond particle. That is, this binder is disadvantageous due to its susceptibility to wear due to mechanical abrasion.

Essentially in a sintered diamond product obtained by strong sintering of ultrafine diamond particles having an average particle size of not more than 1 μm using a Co alloy as a binder, while maintaining a uniform texture, if the content of diamond particles can be increased such in such a way that the binder content of Co or WC-Co alloy can be minimized, an ideal sintered diamond product can be obtained having exceptional excellent resistance to sc to watering, and also wear resistance.

If sintering is carried out using ultrafine particles of diamond having a particle size of not more than 1 μm and a metal of the iron group, such as Co or WC (tungsten carbide) - Co, as starting materials, however, there is often a tendency to anomalous the growth of diamond particles, unless the temperature and pressure conditions during sintering are clearly controlled. This is because the ultrafine particle of diamond is very reactive. In addition, if a high temperature condition is established that is important to facilitate neck growth, and if diamond particles having a particle size not larger than 2 μm are used as starting material, abnormal particle growth is inevitable, and a sintered article containing part of the abnormally grown particles cannot be cut using EDM (Electrical Discharge Machining). In addition, the mechanical strength of diamond is also reduced due to the generation of defects. For this reason, it is difficult to achieve a high yield of sintered diamond products having a particle size of not more than 1 μm and a uniform texture.

As a method for suppressing abnormal growth of diamond particles, a method for controlling abnormal particle growth by placing solid particles such as WC, cBN (cubic boron nitride), SiC (silicon carbide) having a hardness as high as diamond at the grain boundary is known diamond particles. Such a method is described, for example, in Japanese National Patent Publication No. 61-058432 (Patent Document 4), Japanese National Patent Publication No. 06-006769 (Japanese Patent Laid-Open No. 64-017836) (Patent Document 5) and Japanese Patent Laid-Open No. 2003-095743 (Patent Document 6).

Patent Document 1: Japanese National Patent Publication No. 39-020483

Patent Document 2: Japanese National Patent Publication No. 52-012126

Patent Document 3: Japanese National Patent Publication No. 58-032224

(Japanese Patent Laid-Open No. 55-047363)

Patent Document 4: Japanese National Patent Publication No. 61-058432

Patent Document 5: Japanese National Patent Publication No. 06-006769

(Japanese Patent Laid-Open No. 64-017836)

Patent Document 6: Japanese Patent Laid-Open No. 2003-095743

DESCRIPTION OF THE INVENTION

Problems to be Solved by the Invention

In the method described above, however, the direct bonding between diamond particles is physically and chemically blocked by arranging a solid particle having a low affinity for the diamond particle, between the diamond particles or by coating the entire surface of the diamond particle with a binder that does not have catalyst properties ( dissolution and recrystallization) for a diamond particle in order to suppress the abnormal growth of a diamond particle. Accordingly, the formation of the structure as a result of growing a neck from diamond particles is insufficient. As a result, the natural mechanical and thermal characteristics of diamond are deteriorated, and the shear resistance, impact resistance, wear resistance and thermal conductivity of the sintered diamond product are reduced.

From the above purpose of the present invention is to obtain a sintered diamond product having excellent resistance to chipping, impact resistance, wear resistance and thermal conductivity, as well as creating a method for its production.

Problem Solving Tools

As a result of the earliest studies, in order to achieve an improvement in abrasion resistance, wear resistance or the like for a sintered diamond product, the inventors of the present invention found that strength properties, such as shear and impact resistance, wear resistance and thermal conductivity of a sintered diamond product, can be improved by strengthening the direct bond between diamond particles. The authors then investigated a method of suppressing abnormal particle growth by using, instead of commonly used solid particles, a new binder that suppresses excessive dissolution of diamond particles in the binder, while at the same time supporting catalysis (dissolution and re-crystallization) with respect to the diamond particle, as in a binder consisting of Co or WC-Co alloy.

As a result, it was found that if finely dispersed diamond particles having an exceptionally large surface area are used as starting material during sintering, the diamond dissolves in Co, which serves as a binder, quickly and in large quantities, and carbon in the binder , which instantly reaches supersaturation, crystallizes as a thermodynamically stable diamond, which leads to an abnormal growth of diamond particles. To prevent such abnormal particle growth, at least one element selected from the group consisting of Ti (titanium), Zr (zirconium), Hf (hafnium), V (vanadium), Nb (niobium), Ta (tantalum), Cr (chromium) and Mo (molybdenum) are added to Co, serving as a binder, so that its content is not less than 0.5% of the mass. and less than 50 wt .-%, part of the element or the entire element is present in the form of a carbide having an average particle size of at most 0.8 μm, and the texture of the carbide particle is discontinuous. Thus, finely divided carbide serves as a getter, and it also dissolves in Co, to a certain extent, like carbide. For this reason, the dissolution and crystallization of carbon, as a simple substance, in Co can be gradual. In addition to this, the element is controlled in such a way that it does not form a continuous phase so that neck growth between diamond particles can be achieved more easily and a strong structure is formed. In addition, the amount of added binder is small, and the addition of solid particles is not necessary. For this reason, the diamond content in the sintered diamond product increases.

In a sintered product that uses coarse diamond powder, diamond particles sinter more easily as a result of adding an element to the binder. For this reason, the addition of tungsten carbide, as in the usual example, is not necessary, and the wear resistance of the sintered diamond product can be improved.

In a sintered diamond product in accordance with the present invention, carbide particles are present as a discontinuous phase. In other words, a sintered diamond product does not have such a structure that carbide particles bind directly to each other. Since the presence of carbide is less likely to block the bonding between diamond particles, the bonding between diamond particles can be strengthened.

In a sintered fine diamond product containing diamond having an average particle size of not more than 2 μm, in an amount of not less than 90 volume%, which cannot be obtained without abnormal particle growth in the conventional method, it is confirmed that when the content there are more diamond particles in the sintered diamond product; wear resistance and chipping resistance of the sintered product are improved.

In addition to this, it was found that the size of the defect in the sintered product is closely related to strength properties, such as resistance to spallation and impact resistance of the sintered product. Here, the defect refers to a diamond particle having a markedly larger diameter in a sintered diamond product, to a buildup of a binder, such as a solvent, to a gap, or to an area where the bonding (neck growth) between the diamond particles is insufficient (they do not bind or binding is incomplete). When the defect in the sintered diamond product is less, the strength of the sintered product increases.

The sintered diamond product with high strength and high wear resistance in accordance with the present invention, obtained on the basis of these concepts, contains sintered diamond particles having an average particle size of at most 2 μm and a binder phase, as the rest. The content of sintered diamond particles in the sintered diamond product is at least 80% by volume, and at most 98% by volume. The binder phase contains at least one element selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium and molybdenum, the content of which is at least 0.5% by weight. and less than 50 wt. -%, and contains cobalt, the content of which is at least 50% of the mass. and less than 99.5% of the mass. A part of at least one element or the whole of at least one element, where the element is selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium and molybdenum, is present as carbide particles having an average size particles, at most 0.8 microns. The texture of carbide particles is discontinuous, and adjacent diamond particles bind to each other.

In such a sintered diamond product, at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, and Mo is added to the binder. For this reason, even if the diamond particles used as the material have a small diameter, abnormal particle growth can be suppressed without adding solid particles. In addition, even if the diamond particles used as the material have a larger diameter, a sintered diamond product with high strength and high wear resistance, having excellent shear resistance, wear resistance, impact resistance and thermal conductivity, can be obtained by adding this element to a binder. The amount of binder added is not greater than in the usual example, and the diamond content is not less than in the usual example. For this reason, a decrease in wear resistance or the like is not likely.

The average particle size of the sintered diamond particles is selected not more than 2 μm, and preferably not more than 0.8 μm, due to a decrease in the strength of the sintered diamond product due to the splitting of the diamond particle, which should be suppressed.

The reason why the content of sintered diamond particles is selected not less than 80% by volume, and less than 98% by volume, is as follows. Specifically, if the content of sintered diamond particles is selected to be less than 80% by volume, strength properties, such as resistance to spalling and impact resistance, as well as wear resistance, are reduced. At the same time, if the content of diamond particles is selected not less than 98% by volume, a sufficient influence of the binder cannot be obtained, and neck growth does not develop.

The reason why the content of at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, and Mo, is selected not less than 0.5 wt.%, And less than 50% of the mass., Is as follows. Specifically, if the element content is less than 0.5 wt%, the effect of adding the element to suppress the abnormal growth of diamond particles is reduced. In addition, if the content of the element exceeds 50 mass%, the effect of a binder having the property of a catalyst to facilitate the growth of the neck of a diamond particle cannot be obtained sufficiently.

In the present invention, the use of Ti metal as a starting material is most effective both to obtain improved bonding strength between diamond particles and to suppress abnormal particle growth.

Initially, Ti does not carry out catalysis to facilitate neck growth between diamond particles. In the present invention, however, it is contemplated that an appropriate amount of Ti is added to the binder Co having the property of a neck growth catalyst, so that Ti serves as a getter for excess carbon without blocking the catalysis of Co when the carbon is dissolved in the binder. In addition to this, it is also assumed that Ti is converted to carbide as a result of interaction with diamond particles in order to obtain both an improvement in the bonding strength between diamond particles and inhibition of abnormal particle growth.

W (tungsten), like Ti, is also, to some extent, effective in suppressing abnormal particle growth. If the diamond particle has a particle size of not more than 1 μm, however, W is very little effective in suppressing abnormal particle growth. In addition, if W is added instead of Ti, W is present as a WC in the sintered diamond article. For this reason, if metallic Al (aluminum) is cut, Al has an unfavorable tendency to selectively adhere to WC in a sintered diamond product.

A specific method for the production of a sintered diamond product in accordance with the present invention includes a method of grinding a ceramic powder consisting of at least one element selected from the group consisting of ultrafine Ti, Zr, Hf, V, Nb, Ta, Cr and Mo or carbide of these elements, by using a ball mill or the like, and mixing fine diamond powder with it. Here, in order to use a metal powder in order to obtain a texture in which the carbide in the sintered product is finely dispersed and present as an intermittent phase, ultrafine particles should be used as starting material. Since the material of a normal metal has ductility, it is only possible to obtain particles having a particle size of several tens of microns. For this reason, there is a tendency to form a buildup of a binder after sintering, which leads to the appearance of a defect. To obtain a sintered product of the present invention, it is preferable to use metal particles consisting of Ti or the like obtained by the atomization method to obtain ultrafine metal particles having a particle size of not more than a few microns. Similarly, the Co alloy is also preferably finely divided, and it is also preferable to use an ultrafine metal powder, on the order of nanometers, obtained using a titanium reduction-oxidation method in which titanium ion reduction and oxidation reactions are combined.

The sintered product of the present invention can also be obtained by using an ultrafine ceramic powder consisting of carbide and at least one element selected from the group consisting of ultrafine Ti, Zr, Hf, V, Nb, Ta, Cr and Mo. An additional strong bond with diamond can be obtained, however, by the interaction and sintering of diamond particles with metal powder, instead of using ceramic powder. Namely, as a starting material, it is preferable to use particles of a reactive metal, instead of thermally and chemically stable ceramic particles. This is due to the fact that when a metal powder is used, the metal powder leads to the formation of carbide through interaction with a diamond particle, characterized by its low susceptibility to sintering, thereby forming a strong bond with diamond particles.

An ideal method for uniformly and intermittently placing at least one element selected from the group consisting of ultrafine Ti, Zr, Hf, V, Nb, Ta, Cr and Mo or ceramics consisting of their carbide in a sintered diamond product includes It includes a method of applying a coating of a binder to a surface of a powder of diamond particles by using PVD (Physical Vapor Deposition - physical vapor deposition). In particular, if spraying is used, the diamond particle is intermittently coated with a binder containing an ultrafine metal represented by Ti and having a particle size of about 10-100 nm, and in particular about 10-200 nm, whereby a sintered diamond product having Particularly excellent shear and wear resistance.

In a sintered diamond product with high strength and high wear resistance in accordance with the present invention, at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr and Mo is Ti and the Ti content in the binder phase is preferably at least 0.5% by weight and less than 20% by weight.

In a sintered diamond product with high strength and high wear resistance in accordance with the present invention, it is preferable that the test sample be cut from a sintered diamond product in the form of a flat rectangle having a length of 6 mm, a width of 3 mm and a thickness within at least from 0.35 mm, and at most up to 0.45 mm, and is used to measure the transverse tensile strength under conditions of a base of 4 mm, and the measured transverse tensile strength is at least 2.65 GPa.

In addition to this, in a sintered diamond product with high strength and high wear resistance in accordance with the present invention, a test sample is preferably cut from a sintered diamond product in the form of a flat rectangle having a length of 6 mm, a width of 3 mm and a thickness within, at least 0.4 mm, and at most 0.45 mm, are subjected to dissolution treatment in an airtight container, at a temperature in the range of at least 120 ° C to less than 150 ° C, for 3 hours by using a mixture of ft hydrochloric and nitric acid obtained by mixing 40 ml of doubly diluted nitric acid having a concentration of at least 60% and less than 65%, and 10 ml of hydrofluoric acid having a concentration of from 45 to 50%, and then the test sample used to measure lateral tensile strength under a 4 mm base condition, and the measured lateral tensile strength is at least 1.86 GPa.

In a sintered diamond product with high strength and high wear resistance in accordance with the present invention, at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr and Mo is preferably Ti, and the Ti content in the binder phase is at least 1% by mass, and less than 20% by mass. In the X-ray diffraction pattern of a sintered diamond product, measured under conditions of acceleration of an electron beam of 40 kV, a current of 25 mA, a diffraction angle of 2θ = 20-80 ° and a scanning speed of 0.1 ° / second, the diffraction of the beam on titanium carbide in the direction (200) has a ratio of intensities of at least 3% and less than 50% of the diffraction of the beam on the diamond in the (111) direction. Here, "X-ray diffraction intensity" refers to the peak height in the X-ray diffraction pattern using a CuKα beam (characteristic X-rays generated by the shell electrons K Cu).

The inventors also paid attention to oxygen or oxide adsorbed on the surface of a diamond powder serving as a material for manufacturing a sintered diamond product, and found that the strength of the sintered diamond product is improved by removing oxygen or oxide to obtain fewer defects present in the sintered product.

For this reason, preferably the sintered diamond product contains oxygen in an amount of at least 0.001% of the mass. and less than 0.15% of the mass. The proportion of oxygen is selected to at least 0.001% of the mass. and less than 0.15% by weight, since using modern technology it is impossible to establish an oxygen proportion of less than 0.001% by weight, and since the strength of a sintered diamond product is similar to that of a conventional example, if it is brought to at least 0.15 % of the mass.

A sintered diamond product in accordance with the present invention can inhibit abnormal particle growth. For this reason, it is also possible to sinter under conditions of higher pressure or temperature. Usually, as a rule, in industry the pressure is brought to 5.5 GPa, and the temperature is brought to about 1000 ° C, i.e. the necessary and sufficient pressure is established. If a higher pressure is set as a sintering condition, the fine diamond particles can sinter to obtain a higher content. In addition, sintering at a higher pressure can facilitate neck growth.

In accordance with the method of manufacturing a sintered diamond product with high strength and high wear resistance of the present invention, it is desirable to sinter by holding for 10 minutes, under pressure conditions ranging from no lower than 5.7 GPa to no higher than 7 , 5 GPa, and at temperatures ranging from no lower than 1500 ° C to no higher than 1900 ° C. If the pressure is higher than 7.5 GPa, it is impractical from the point of view of the service life of the mold of the ultra-high pressure generator. If the temperature is set higher than 1900 ° C, the diamond-graphite equilibrium line crosses from bottom to top and the system falls into the region of stable graphite. In this case, the graphitization of diamond occurs. Taking into account the service life of the mold of the ultra-high pressure generator and the performance of the product from sintered diamond, sintering by exposure for 10 minutes under the condition of pressure ranging from no lower than 6.0 GPa to no higher than 7.2 GPa and temperatures ranging from no lower than 1500 ° C to no higher than 1900 ° C are more preferred.

The effects of the present invention

According to a sintered diamond product with high strength and high wear resistance and the manufacturing method of the present invention, particle growth can be suppressed without using solid particles having a low affinity for a diamond particle. For this reason, the direct bond between diamond particles can be further strengthened. As a result, a sintered diamond product with high strength and high wear resistance can be obtained, having excellent wear resistance, shear resistance, impact resistance and thermal conductivity.

Brief Description of the Drawings

Figure 1 is a photograph taken under a microscope showing the texture of sample 1E in example 1.

Figure 2 is a photograph taken under a microscope, at a higher magnification than in figure 1, showing the texture of sample 1E.

Figure 3 is a photograph taken under a microscope showing the texture of sample 1H in example 1.

Figure 4 is a photograph taken under a microscope at a higher magnification than in Figure 3, showing the texture of sample 1H.

5 is a photograph taken under a microscope showing the texture of a sintered diamond product in which particles grow abnormally.

BEST MODES FOR CARRYING OUT THE INVENTION

One of the embodiments of the present invention will be presented in the examples below.

(Example 1)

In the present example, the average particle size of the sintered diamond product powder, the sintered diamond particle content of the sintered diamond product, and the binder composition are changed, and the lateral tensile strength and the amount of wear on the back surface are measured. Specifically, a vacuum oven containing a rotary mixer is used to dryly mix diamond powder having an average particle size of 0.8 μm and a mixture of powders of metallic Co and metallic Ti serving as a binder, under conditions such as a vacuum level of 0.1 Pa, oven temperature 300 ° C and 2000 rpm. The mixed powder of diamond and various binders is filled into a container made of Ta (tantalum), in a state where the mixture is in contact with a disk made of hard alloy WC - 6% Co, and is allowed to sinter for 10 minutes, under conditions pressure from 5.7 GPa to 7.2 GPa and temperatures from 1500 ° C to 1900 ° C, when using a Belt type ultra-high pressure device. A sample in which Ti is added is provided to observe the texture on the surface of the finished sintered body in order to determine if Ti is present in a continuous or discontinuous phase. A diamond particle that is grown to a particle size of not less than 300 microns during sintering is considered an abnormally grown particle, and the number of such particles is counted. All sintered products are processed into test specimens in the form of bars having dimensions 6x3x0.3 mm, and then their lateral tensile strength is measured in a three-point bend test under a 4 mm base condition. In addition, a cutting chip (ISO standard: TPGN160304) having a main surface in the shape of a regular triangle is made from a sintered product and subjected to a cutting test, in which the amount of wear on the back surface is measured. In the test when cutting a round rod made of an alloy of Al (aluminum) containing 16% of the mass. Si is used as the material to be cut, and the test is carried out using a cooling emulsion, under operating conditions a cutting speed of 800 m / min, a cutting depth of 0.5 mm, a feed rate of 0.12 mm / rev and a cutting time of 5 minutes . The result is shown in Table 1. In Table 1, a sintered diamond product in accordance with the present invention is represented by Samples 1E and 1G. As a result of X-ray diffraction analysis of samples 1E and 1G, it was found that part of the added Ti is present as TiC.

Table 1 Special product sample The average particle size of the diamond (microns) The content of diamond particles (% vol.) The prepared binder composition (% wt.) The composition of the phase of the binder of the sintered product
(% wt.) Presence Ti Counting Abnormally Grown Particles (Amount) Sintering conditions Transverse tensile strength (GPa) The amount of wear on the rear surface (microns) Pressure (GPa) Tempera Tour (° C) 1A 0.8 78 Co: 100% Co: 95.2%, W: 2.8% - 258 5.7 1500 1.35 77 1B 0.8 78 Co: 75%,
Ti: 25% Co: 77.5%, Ti: 16.0%,
W: 2.8% Intermittent 0 5.8 1500 2.54 65 1C 0.8 78 Co: 75%,
W: 25% Co: 71.2%, W: 23.8% - eleven 5.7 1500 2.30 70 1D 0.8 90 Co: 100% Co: 94.8%, W: 2.2% - 231 6.2 1600 1.42 72 1E 0.8
The present invention 90 Co: 75%,
Ti: 25% Co: 77.8%, Ti: 16.1%,
W: 2.4% Intermittent 0 7.2 1900 2.85 43 1F 0.8 90 Co: 75%,
W: 25% Co: 70.4%, W: 25.6% - eighteen 6.8 1800 2.35 56 1G 0.8
Regular product 90 Co: 50%,
Ti: 50% Co: 44.6%, Ti: 46.2%,
W: 1.9% Intermittent 0 7.0 1900 2.76 49 1H 0.8 90 Co: 50%,
W: 50% Co: 56.2%, W: 40.8% - 3 6.7 1750 2.26 61 1I 0.8 90 Co: 40%,
Ti: 60% Co: 31.9%, Ti: 51.8%,
W: 2.6% Solid 0 6.5 1600 2.03 68 1J 0.8 90 Co: 99.5%,
Ti: 0.5% Co: 93.5%, Ti: 0.2%,
W: 2.3% Intermittent 215 6.8 1900 1.41 71 1K 2.5 90 Co: 100% Co: 90.9%, W: 6.1% - one 6.5 1600 1.94 57 1L 2.5 90 Co: 75%,
Ti: 25% Co: 76.5% Ti: 16.8%,
W: 2.7% Intermittent 0 6.5 1600 1.85 58 1M 2.5
Regular product 85 Co: 75%,
W: 25% Co: 70.1%, W: 25.9% - 0 6.0 1600 1.78 61 1N 0.8 99 Co: 75%,
Ti: 25% Co: 76.8%, Ti: 14.1%,
W: 5.1% Intermittent 0 7.2 1900 2.03 69

As shown in table 1, in samples 1A and 1D, in which when preparing the composition of the binder used 100% of the mass. Co and diamond powder have an average particle size of 0.8 μm, a large number of abnormally grown particles are observed (258 and 231 particles, respectively). In addition to this, a number of abnormally grown particles (11, 8 and 3 particles, respectively) are generated in 1C, 1F and 1H, in which W. is added to the binder. On the other hand, in samples 1B, 1E, 1G, 1I and 1N in which the phase of the binder contains at least 0.5% of the mass. Ti and diamond powder have an average particle size of 0.8 μm, abnormal particle growth is barely observed. Therefore, it can be seen that abnormal particle growth can be suppressed when the content of the binder phase is at least 0.5% by weight. Ti.

In addition, when comparing sample 1E, in which diamond powder has an average particle size of 0.8 μm, and sample 1L, in which diamond powder has an average particle size of 2.5 μm, the transverse tensile strength of sample 1E is greater. than sample 1L. Therefore, it can be seen that by choosing the average particle size of the diamond particles not larger than 2 μm, the shear resistance improves.

In addition, when comparing samples 1B and 1C containing 78% vol. sintered diamond particles, and samples 1E and 1F containing 90% vol. sintered diamond particles, the transverse tensile strength of samples 1E and 1F is greater than that of samples 1B and 1C, and the amount of wear on the rear surface of samples 1E and 1F is less than that of samples 1B and 1C. Therefore, it can be seen that by choosing a sintered diamond particle content of not less than 80% by volume, shear and wear resistance are improved.

In addition, when comparing sample 1E containing 16.1% of the mass. Ti in the phase of the binder and sintered under conditions of pressure of 7.2 GPa and a temperature of 1900 ° C, and sample 1F containing 25.6% of the mass. W in the binder phase and sintered under pressure conditions of 6.8 GPa and a temperature of 1800 ° C, the transverse tensile strength of specimen 1E is greater than that of specimen 1F, and the wear on the back surface of specimen 1E is less than that of specimen 1F. When comparing a sample of 1G containing 46.2% of the mass. Ti in the phase of the binder and sintered under pressure conditions of 7.0 GPa and a temperature of 1900 ° C, and a 1H sample containing 40.8% of the mass. W in the binder phase and sintered under conditions of pressure of 6.7 GPa and a temperature of 1750 ° C, the transverse tensile strength of specimen 1G is greater than that of specimen 1H, and the wear on the back surface of specimen 1G is less than that of specimen 1H. Since abnormal particle growth can be suppressed with Ti content in the binder phase, the pressure and temperature, which are sintering conditions, can be set higher. Therefore, it can be seen that shear resistance and wear resistance can be improved.

Samples 1E and 1G in accordance with the present invention have a higher lateral tensile strength and lower wear on the rear surface than sample 1M, which is a common product. In addition to this, it can be seen that abnormal particle growth does not occur in a 1K sample having an average particle size of not less than 2 μm, even if Ti is not added. Sample 1N containing 99% of the mass. diamond particles, has a low transverse tensile strength and a large amount of wear on the rear surface. Therefore, it can be seen that cervical growth achieved with a binder is insufficient.

(Example 2)

In the present example, the average particle size of Ti contained in the binder is changed, and the transverse tensile strength and the amount of wear on the back surface are measured. Specifically, a ball mill is used to mix diamond powder having an average particle size of 0.8 microns and having a content of 90% vol., And a binder containing 75% of the mass. Co and 25% of the mass. Ti. The binder uses Ti having various average particle sizes: 0.1 μm, 0.8 μm, 0.9 μm and 1.0 μm. After that, a sinter Belt type ultra-high pressure device is used for sintering, in which the mixture is kept for 10 minutes at a pressure of 7.2 GPa and a temperature of 1900 ° C. The transverse tensile strength of the obtained sintered product is measured using the same method as in example 1, and its amount of wear on the rear surface is measured by cutting tests. The result is presented in table 2.

table 2 Sintered Sample The average particle size of the diamond (microns) Diamond particle content
(% volume) The composition of the binder (% wt.) The composition of the phase of the binder of the sintered product
(% wt.) Particle Size Ti (μm) Counting Abnormally Grown Particles (Amount) Transverse tensile strength (GPa) The amount of wear on the rear surface (microns) 2A
For real
invention 0.8 90 Co: 75%,
Ti: 25% Co: 78.0%, Ti: 16.2%,
W: 3.1% 0.1 0 2.85 43 2B
For real
invention 0.8 90 Co: 75%,
Ti: 25% Co: 77.5%, Ti: 16.0%,
W: 2.8% 0.8 0 2.79 46 2C
Comparable
product 0.8 90 Co: 75%,
Ti: 25% Co: 77.8%, Ti: 16.1%,
W: 2.9% 0.9 3 2.46 48 2D
Comparable
product 0.8 90 Co: 75%,
Ti: 25% Co: 76.8%, Ti: 16.5%,
W: 2.6% 1.0 25 2.01 fifty 2E
For real
invention 0.8 90 Co: 50%,
Ti: 50% Co: 45.1%, Ti: 46.1%,
W: 2.0% 0.1 0 2.69 60 2F
For real
invention 0.8 90 Co: 50%,
Ti: 50% Co: 44.6%, Ti: 46.2%,
W: 1.9% 0.8 0 2.66 63 2G
Comparable
product 0.8 90 Co: 50%,
Ti: 50% Co: 44.1%, Ti: 45.7%,
W: 2.1% 0.9 four 2.26 66 2H
Comparable
product 0.8 90 Co: 50%,
Ti: 50% Co: 42.9%, Ti: 46.8%,
W: 2.3% 1.0 25 2.06 65

As shown in table 2, the values of wear on the rear surface of samples 2A - 2D are essentially the same, and the values of wear on the rear surface of samples 2E - 2H are essentially the same. At the same time, the transverse tensile strength of samples 2A and 2B is greater than that of samples 2C and 2D, and the transverse tensile strength of samples 2E and 2F is greater than that of samples 2G and 2H. In addition to this, consider the number of diamond particles, which during sintering grow to a particle size of not less than 300 microns. As a result, abnormal particle growth was not observed in samples 2A, 2B, 2E, and 2F. On the other hand, abnormal particle growth is observed in samples 2C, 2D, 2G, and 2H (3, 25, 4, and 25 particles, respectively). Therefore, it can be seen that by choosing an average particle size of Ti in a binder of no more than 0.8 μm, abnormal particle growth is effectively suppressed, and spalling resistance is improved since neck growth is not suppressed.

(Example 3)

In the present example, the Ti addition method to be added to the binder is changed, and the lateral tensile strength and the amount of wear on the back surface are measured. Specifically, sample 3A is prepared by mixing, using a ball mill, a diamond powder having an average particle size of 0.8 μm and having a content of 90% by volume, and a binder containing 75% by weight. Co and 25% of the mass. Ti. In addition, sample 3B, having a similar composition, is prepared by applying a Ti coating to a diamond powder using an RF (Radio Frequency) PVD sputter. In addition, a 3C sample having a similar texture is prepared by coating Ti with a diamond powder using a CVD (Chemical Vapor Deposition) device, so that the coating layer has a thickness of 0.1 μm over the entire surface of the diamond particle . Each of samples 3A - 3C is placed in a container made of Ta (tantalum), in a state where the sample is in contact with a disk made of hard alloy WC - 6% Co, and is allowed to sinter for 10 minutes under pressure conditions 7 , 2 GPa and temperatures of 1900 ° C through the use of a Belt type ultra-high pressure device. The transverse tensile strength of the obtained sintered product is measured by using the same method as in example 1, and its wear on the rear surface is measured in a cutting test. The result is shown in table 3.

Table 3 Sintered Sample The average particle size of the diamond (microns) Diamond particle content
(%) The composition of the binder (% wt.) The composition of the phase of the binder of the sintered product
(% wt.) Particle Size Ti (μm) The way to add
laziness
Ti Lateral strength
tensile strength (GPa) Great
rank
wear
by ass
its surface (mm) 3A 0.8 90 Co: 75%,
Ti: 25% Co: 79.8%,
Ti: 17.1%,
W: 3.1% 0.1 Mixing
with the help of a ball
howling 2.59 53 3B 0.8 90 Co: 75%,
Ti: 25% Co: 79.8%,
Ti: 17.0%,
W: 3.2% 0.1 PVD 2.88 39 3C 0.8 90 Co: 75%,
Ti: 25% Co: 79.6%,
Ti: 17.2%,
W: 3.2% Coating layer
Tiya, approx.
0.1 CVD 2.46 55

As shown in Table 3, a coated sample 3B using an RF PVD spraying device exhibits a lateral tensile strength and an amount of wear at the rear surface that is superior to sample 3A in which Ti is added by mixing with a ball mill and sample 3C wherein diamond particles coat Ti by using the CVD method. The texture and surface of each sample are observed using a metallurgical microscope. In sample 3A, Co or Ti separation is observed, and a uniform texture is not obtained. In addition, the average particle size of Ti carbide is 1.0 μm, which is larger than during addition. In samples 3B and 3C, no Co or Ti separation is observed, and a uniform texture is obtained. In sample 3C, however, the TiC texture is solid, since the entire surface of the diamond particle has a uniform coating, and not only abnormal particle growth is suppressed, but also neck growth between diamond particles. In sample 3B, the coating of the Ti diamond particle is not completely uniform, but partial, i.e. discontinuous, and the average particle size of the Ti powder is maintained at approximately 0.1 μm. As a result, it has been found that Ti is preferably added by coating with an RF PVD sputter. It has also been found that a decrease in lateral tensile strength or an increase in the amount of wear on the rear surface is caused if the carbide has an average particle size greater than 0.8 μm, or if the texture of the carbide itself is solid.

(Example 4)

In the present example, a change in the transverse tensile strength is observed when samples 3A - 3C in Example 3 are subjected to dissolution processing. Specifically, a test sample cut from a sintered diamond product represented by samples 3A - 3C in Example 3, in the form of a flat rectangle having a length of 6 mm, a width of 3 mm and a thickness of 0.4 to 0.45 mm, is subjected to dissolution processing in a sealed container at a temperature not lower than 120 ° C and lower than 150 ° C for 3 hours using a mixture of hydrofluoric and nitric acid obtained by mixing 40 ml of twice diluted nitric acid having a concentration of at least 60 %, and less than 65%, and 10 ml of hydrofluoric acid having a concentration of from 45 to 50%. Among the test samples (samples) obtained by the method described above, a sample that was identified as sample 3A is identified as sample 4A, and a sample that was identified as sample 3B is identified as sample 4B, and a sample that was identified as sample 3C is identified as sample 4C. Using each sample, the transverse tensile strength is measured under the condition of a base of 4 mm. The result is shown in table 4.

Table 4 Sintered sample The average particle size of the diamond (microns) Diamond content
(%) The composition of the binder (% wt.) The composition of the phase of the binder of the sintered product
(% wt.) Particle Size Ti (μm) The way to add
laziness
Ti Cross Strength
tensile strength (GPa) Dissolution Processing 4A 0.8 90 Co: 75%,
Ti: 25% Co: 79.8%,
Ti: 17.1%,
W: 3.1% 0.1 Mixing
with the help of a ball
howling 2.02 Yes 4B 0.8 90 Co: 75%,
Ti: 25% Co: 79.8%,
Ti: 17.0%,
W: 3.2% 0.1 PVD 2.59 Yes C 0.8 90 Co: 75%,
Ti: 25% Co: 79.6%,
Ti: 17.2%,
W: 3.2% Coating, approx. 0.1 CVD 1.98 Yes

As shown in table 4, the transverse tensile strength of sample 4B, in which Ti is added through the use of RF devices for PVD deposition, decreases by only 0.22 GPa, from 2.88 GPa to 2.59 GPa. In contrast, the transverse tensile strength of sample 4A, in which Ti is added by mixing with a ball mill, decreases significantly, by 0.57 GPa, from 2.59 GPa to 2.02 GPa. In addition to this, the transverse tensile strength of sample 4C, in which Ti is added using CVD, also decreases significantly, by 0.48 GPa, from 2.46 GPa to 1.98 GPa. Therefore, it can be seen that neck growth between diamond particles develops and a strong structure is formed when Ti is added using an RF PVD sputtering device, that is, through the development of a discontinuous texture of Ti itself.

(Example 5)

In the present example, the proportion of Ti in the binder is changed and the intensity ratio between the diffraction of the beam by TiC in the direction (200) and the diffraction of the beam by diamond in the direction (111) in the obtained sintered product is measured. Specifically, three types of samples are prepared: sample 5A containing 78% vol. diamond powder and material to be sintered, containing 75% by mass of Co and 25% by mass of Ti; sample 5B containing 90% vol. diamond powder and material to be sintered, containing 75% by mass of Co and 25% by mass of Ti; and sample 5C containing 90% vol. diamond powder and material to be sintered, containing 50% by mass of Co and 50% by mass of Ti. In all samples, the average particle size of the diamond powder is selected equal to 0.8 microns. After that, a sinter Belt type ultra-high pressure device is used for sintering, in which the sample is held for 10 minutes at a pressure of 7.2 GPa and a temperature of 1900 ° C. The characteristic X-rays generated from the electrons of the K Cu shell are used to measure the X-ray diffraction pattern of the obtained sintered diamond product under conditions of electron beam acceleration for irradiating a 40 kV Cu target, a current of 25 mA, a diffraction angle of 2θ from 20 to 80 ° and a scanning speed of 0 , 1 ° / second, and measure the intensity ratio between the diffraction of the beam by TiC in the (200) direction and the diffraction of the beam by diamond in the (111) direction. The result is shown in table 5. In table 5, sample 5B is a sintered diamond product in accordance with the present invention.

Table 5 Sintered sample Medium
niy time-mer hour diamond
(microns) Diamond particle content
(% vol.) The composition of the material, which must be sintered (% wt.) The composition of the phase of the binder of the sintered product
(% wt.) X-ray diffraction intensity ratio The amount of wear on the rear surface
(microns) 5A 0.8 78 Co: 75%, Ti: 25% Co: 79.8%,
Ti: 17.1%,
W: 3.1% 57% 65 5B 0.8 90 Co: 75%, Ti: 25% Co: 79.8%,
Ti: 17.0%,
W: 3.2% 40% 39 5C 0.8 90 Co: 40%, Ti: 60% Co: 31.9%,
Ti: 51.8%,
W: 2.6% 61% 68

As shown in table 5, the ratio of the x-ray diffraction intensities of sample 5B having the smallest amount of wear on the rear surface is 40%. Samples 5A and 5C, on the other hand, have an intensity ratio greater than 50%. Therefore, it can be seen that the amount of wear on the back surface tends to increase in the sample having a ratio of TiC intensities in excess of 50%. In addition to this, it can also be seen that the ratio of the intensity of diffraction of the beam by TiC in the (200) direction is preferably in the range of not less than 0.01% to less than 50% of the diffraction of the diamond beam in the (111) direction since there is an abnormal particle growth in a sintered product that does not contain Ti in the binder composition.

(Example 6)

In the present example, the amount of oxygen contained in the sintered diamond product is changed, and the lateral tensile strength and the amount of wear on the back surface are measured. Specifically, a diamond powder having an average particle size of 0.8 μm and having a content of 90% by volume and a binder containing 75% by mass of Co and 25% by mass of Ti is mixed. After that, the resulting mixtures are subjected to heat treatment for 60 minutes, in vacuum, at temperatures of 1000 ° C, 1100 ° C and 1250 ° C, respectively, in order to restore the binder and partially graphitize the diamond particles from the surface. After that, a sinter Belt type ultra-high pressure device is used for sintering, in which the sample is held for 10 minutes at a pressure of 7.2 GPa and a temperature of 1900 ° C. Among the samples obtained, a sample that was subjected to heat treatment at a temperature of 1000 ° C is identified as sample 6A; a sample that has been heat treated at 1100 ° C is identified as sample 6B; and a sample that was subjected to heat treatment at a temperature of 1250 ° C is identified as sample 6C. The amount of oxygen contained in samples 6A - 6C was measured using ICP (Inductively Coupled Plasma - Inductively Coupled Plasma). In addition, the transverse tensile strength of samples 6A to 6C is measured using the same method as in Example 1. The result is shown in Table 6.

Table 6 Specimen Sample Medium
diamond particle size
(microns) Diamond particle content
(% vol.) Composition
tion of the material which
must bake
(% mass) The composition of the phase of the binder of the sintered product
(% mass) Tempe ratu
pa heat
wa
(° C) Oxygen content
(% mass) Lateral strength
tensile strength (GPa) 6A 0.8 90 Co: 75%,
Ti: 25% Co: 79.8%, Ti: 17.1%, W: 3.1% 1050 0.20 2.04 6B 0.8 90 Co: 75%,
Ti: 25% Co: 79.8%, Ti: 17.0%, W: 3.2% 1150 0.14 2.44 6C 0.8 90 Co: 75%,
Ti: 25% Co: 79.6%, Ti: 17.2%, W: 3.2% 1250 0.05 2.59

As shown in table 6, if the temperature of the heat treatment before sintering changes, the amount of oxygen contained in the sintered diamond product also changes. If the amount of oxygen is not greater than 0.15% of the mass, the transverse tensile strength is significantly improved. Therefore, it can be seen that the resistance to chipping improves when the oxygen content in an amount less than 0.15% of the mass.

(Example 7)

In the present example, sintered diamond products presented as sample 1E (of the present invention) and sample 1H (typical example) in example 1 are treated with acid and photographed under a microscope. Figure 1 is a photograph taken with a microscope, showing the texture of sample 1E in example 1. Figure 2 is a photograph taken with a microscope, at a magnification higher than in figure 1, showing the texture of sample 1E. Figure 3 is a photograph taken with a microscope, showing the texture of sample 1H in example 1. Figure 4 is a photograph taken with a microscope at a magnification higher than in figure 3, showing the texture of sample 1H.

Turning to FIGS. 1-4, a plurality of shallow recesses scattered over the entire surface correspond to parts that represent the phase of the binder. The phase volume of the binder in FIGS. 1 and 2, showing a sintered diamond product in accordance with the present invention, is smaller than the phase volume of the binder in FIGS. 3 and 4, showing a conventional sintered diamond product. Therefore, it can be seen that in the present invention, the neck growth of diamond particles is not blocked by the phase of the binder.

5 is a microscopic photograph showing the texture of a sintered diamond product in which particles abnormally grow. Turning to FIG. 5, a small spot is a diamond particle that has grown abnormally. A diamond particle that has grown abnormally has a particle size of no less than 300 microns. A large number of such abnormally grown particles are observed in a conventional sintered diamond product. The present invention can suppress such abnormally grown particles.

The examples described above are intended to be illustrative and should not be construed as limiting, the essence and scope of the present invention are not limited by the examples given above, but by the claims, and are intended to include all modifications and variations within the scope of the claims.

Claims (7)

1. Sintered diamond product with high strength and high wear resistance, containing sintered diamond particles having an average particle size of at most 2 μm, and the phase of the binder, as the remaining part, in which the content of these sintered diamond particles in the specified sintered diamond product at least 80 vol.% and at most 98 vol.%,
the specified phase of the binder contains at least one element selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium and molybdenum, the content of which is at least 0.5 wt.% and less than 50 wt.%, and contains cobalt, the content of which is equal to at least 50 wt.% and less than 99.5 wt.%,
a part of said at least one element or said at least one element as a whole, selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium and molybdenum, is present in the form of carbide particles having average particle size, at most, 0.8 microns,
the texture of said carbide particle is discontinuous, and adjacent said diamond particles are bonded to each other, while the measured transverse tensile strength of the test sample cut from the specified sintered diamond product in the form of a flat rectangle having a length of 6 mm, a width of 3 mm and a thickness of the range of at least 0.4 mm, at most, to 0.45 mm used to measure the transverse tensile strength under conditions of a base of 4 mm is at least 2.65 GPa. 2. Sintered diamond product with high strength and high wear resistance according to claim 1, in which
said at least one element selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium and molybdenum, is titanium, and
the content of said titanium in said binder phase is at least 0.5 wt.% and less than 20 wt.%. 3. Sintered diamond product with high strength and high wear resistance according to claim 1, in which
the test sample is cut from the specified sintered diamond product in the form of a flat rectangle having a length of 6 mm, a width of 3 mm and a thickness in the range of at least 0.4 mm, at most up to 0.45 mm, and is subjected to dissolution processing in a sealed container at a temperature in the range of at least 120 ° C. to less than 150 ° C. for 3 hours by using a mixture of hydrofluoric and nitric acid obtained by mixing 40 ml of doubly diluted nitric acid having a concentration of at least at least 60%, and less than 65%, and 10 ml of hydrofluoric acid, having a concentration of from 45 to 50%, and then the test sample is used to measure the transverse tensile strength under conditions of a base of 4 mm, and the measured transverse tensile strength equal to at least 1.86 GPa. 4. Sintered diamond product with high strength and high wear resistance according to claim 1, in which
said at least one element selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium and molybdenum, is titanium,
the content of said titanium in said phase of the binder is at least 0.5 wt.% and less than 20 wt.%,
in the X-ray diffraction pattern of the indicated sintered diamond product, measured under conditions of acceleration of an electron beam at 40 kV, a current of 25 mA, a diffraction angle of 2θ from 20 to 80 ° and a scanning speed of 0.1 ° / s, the diffraction of the beam on titanium carbide in the direction (200 ) has a ratio of intensities of at least 3% and less than 50% of the beam diffraction by diamond in the (111) direction. 5. Sintered diamond product with high strength and high wear resistance according to claim 1, in which the specified sintered diamond product contains oxygen in an amount of at least 0.001 wt.% And less than 0.15 wt.%. 6. A method of manufacturing a sintered diamond product with high strength and high wear resistance according to claim 1, in which the sintering is carried out under pressure conditions in the range of at least 5.7 GPa, at most up to 7.5 GPa and a temperature in the range at least 1400 ° C, at most, up to 1900 ° C, using a Belt type ultra-high pressure device. 7. A method of manufacturing a sintered diamond product with high strength and high wear resistance according to claim 6, in which the sintering is carried out under pressure conditions in the range of at least 6.0 GPa, at most, up to 7.2 GPa and a temperature in the range at least 1400 ° C, at most, up to 1900 ° C, using a Belt type ultra-high pressure device.

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