RU2334550C2 - Diamond tool, synthetic monocrystallic diamond, method of monocrystallic diamond synthesis, and diamond jewelry - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention claims diamond tool manufactured with monocrystallic diamond, synthesised under high pressure by temperature gradient method, so that the claimed diamond crystal contains not more than 3 parts per million of nitrogen. The tool features a blade with its edge oriented in plane (110), so that Knoop scale hardness at the plane (100) in direction <110> is higher than in direction <100>. Such synthetic monocrystallic diamond is synthesised by temperature gradient method under superhigh pressure and high temperature, and its crystals contain nickel atoms introduced by atomic substitution or boron and nickel atoms introduced by atomic substitution.

EFFECT: obtaining cheap synthetic monocrystallic diamonds with reduced flaw number.

24 cl, 4 ex, 2 tbl, 7 dwg

Description

FIELD OF THE INVENTION

The present invention relates generally to diamond tools, synthetic single crystal diamonds, methods for synthesizing single crystal diamonds and diamond jewelry, and in particular to diamond tools having excellent performance, such as diamond cutters, knives, and the like. having a sharp cutting edge, excellent in resistance to abrasion, destruction, etc. and stable in quality, diamond dies, diamond tools for sharpening, diamond tools and the like, excellent in resistance to abrasion, to synthetic single-crystal diamonds having a crystal containing nickel as a result of atomic substitution, and to methods for synthesizing such single-crystal diamonds , to synthetic single-crystal diamonds having a crystal containing boron and nickel as a result of atomic substitution, and to methods for synthesizing such single-crystal diamonds, as well as to diamond jewelry m, having a bright color.

State of the art

Conventional single-crystal diamond-based tools were previously made using natural diamonds appropriately selected from rough diamonds. In addition, some conventional single-crystal diamond-based tools were made using artificial, synthetic single-crystal diamonds (type Ib) containing nitrogen as an impurity.

Diamond is widely used for various purposes in industry, for the manufacture of jewelry and the like, since diamond has extremely high hardness and sufficiently significant thermal conductivity and has a high refractive index and therefore has a bright luster ("play of light"). However, natural diamond is quite expensive. Accordingly, industrially made diamonds are widely used mainly in various industries. Such industrially made diamonds are usually synthesized by a temperature gradient method or a similar method of growing crystals under ultra-high pressure at high temperature (as described in patent documents 1-6).

In addition, according to recent industrial improvements, synthetic diamond single crystals, homogeneous, etc. have also been created. and excellent in resistance to abrasion and correspondingly superior in mechanical and physical properties to natural diamond (as described in patent documents 7-9).

In addition, a synthetic single crystal diamond has also been created, which is semi-conductive or electrically conductive or similarly has a property that is not inherent in diamond (as described in patent document 10).

Patent Document 1: Japanese Patent Laid-Open No. 60-12747

Patent Document 2: Japanese Patent Laid-Open No. 5-137999

Patent Document 3: Japanese Patent Laid-Open No. 5-138000

Patent Document 4: Japanese Patent Laid-Open No. 5-329356

Patent Document 5: Japanese Patent Laid-Open No. 6-182182

Patent Document 6: Japanese Patent Laid-Open No. 6-182184

Patent Document 7: Japanese Patent Laid-Open No. 3-131407

Patent Document 8: Japanese Patent Laid-Open No. 3-228504

Patent Document 9: Japanese Patent Laid-Open No. 7-116494

Patent Document 10: Japanese Patent Laid-Open No. 5-200271

Non-Patent Document 1: Sumiya et al., Diamond and Related Materials, 5, 1359 (1996).

Disclosure of invention

Problems Solved by the Invention

Since natural diamond contains a large amount of nitrogen as an impurity and, in addition, reflects the complex history of its growth in the bowels of the Earth, its crystals have a large number of stresses and crystalline defects, and there are also large differences between them. In essence, it is impossible to constantly obtain from natural diamond a high-quality crystal that does not contain impurities, crystalline defects, and the like. Such crystalline defects of natural diamond, impurities and the like serve as a place in which it is possible to initiate its destruction. As such, conventional tools made using natural diamond are unreliable in quality and vary considerably in their performance, service life, etc.

On the contrary, synthetic diamond single crystals grown under high pressure at a high temperature, allowing the diamond to be in a thermodynamically stable state, surpass natural diamond in crystallinity and, moreover, are more stable in quality compared to natural diamond. However, a typical synthetic diamond contains from several tens to several hundred parts per million (ppm) of nitrogen in the form of isolated substitutional impurities (i.e. type Ib) that affect a number of characteristics. In particular, in the ultraviolet and infrared regions of the spectrum, an admixture of nitrogen causes significant absorption. In addition, the admixture of nitrogen in the crystal is not evenly distributed. As such, inside the crystal is in a more or less stressed state.

In addition, among artificial synthetic diamonds, those that are of type Ib and contain an admixture of nitrogen as isolated substitutional impurities, are used for the manufacture of cutting tools, knives and the like. And although artificial synthetic diamond is superior in quality stability to natural diamond, so far it has still been insufficient in terms of sharpness and abrasion resistance, which determine the characteristics of tools.

When the temperature gradient method is used for diamond synthesis without using a metal solvent containing a special nitrogen getter added to it, the nitrogen contained in the solvent can be captured in the crystal, which leads to a yellow color of the diamond, which is also described in patent documents 2-6.

This nitrogen is an atomic substitutional impurity, and, in addition, the nitrogen atom has a larger size than the carbon atom. This causes partial distortion of the cubic crystal structure of diamond. As a result, diamond lowers hardness and thermal conductivity.

In particular, when diamond is used for industrial purposes as a cutting edge of a tool, such deteriorated properties as described above not only directly impair the product's resistance to grinding (polishing), abrasive wear and the like, but also cause problems in the manufacturing process of the product and therefore, indirectly impair product performance.

More precisely, the diamond is ground off to form a cutting edge from it. This causes friction and, consequently, the release of heat, and the lower the thermal conductivity of the diamond, the slower this heat is removed, and therefore the cutting edge of the blade is excessively heated and oxidized. This leads to the appearance on the cutting edge in its active part of the step of approximately 0.04 mm, usually called the sector. As a result, the sharpness of the active part of the blade as a tool decreases, and the surface of the product after grinding is polished with poor accuracy.

In addition, to ensure synthetic diamonds having improved mechanical properties, semiconductor conductivity and electrical conductivity that is not inherent in diamond, boron (B) is also introduced into the diamond crystal, which was also described in patent documents 9 and 10. However, to implement this, as carbon source requires a special type of diamond powder, and the current level of technological development for this is still not enough.

In addition, a diamond having a yellow color, in particular a dark yellow color, instead of being transparent or having a color such as blue and red, has a lower cost as a jewelry. In addition, it is also difficult to use as optical components, a laser window, and the like.

To prevent the entry of nitrogen into the diamond crystal, a number of methods have been developed with the addition of aluminum (Al), titanium (Ti), zirconium (Zr), or a similar nitrogen getter in a metal solvent in the production of diamond. These methods can provide diamond with a reduced nitrogen content and, moreover, colorless and transparent. However, in order to prevent the capture by the diamond crystal of carbides formed by the getter of nitrogen in the solvent, this crystal must be grown at a reduced rate. This has also been accomplished using a variety of methods, which are described in patent documents 2-6. Currently, the crystal is grown at a rate of from 2 mg / h to 2.5 mg / h maximum. This affects the increase in the cost of its production.

In addition, semiconductor conductivity and electrical conductivity are properties that are not inherent in diamond, and these properties, currently achieved, are still insufficient.

Thus, there is still a need for a synthetic single crystal diamond having a low content of impurity or nitrogen and produced inexpensively for industrial purposes, in particular for use as a tool. In addition, there is also a need for synthetic single crystal diamond with improved abrasion resistance or similar mechanical and physical properties. Similarly, there is also a need for synthetic single crystal diamond with a semiconductor conductivity corresponding to the level of electrical conductivity. In addition, there is also a need for a synthetic single crystal diamond, which has a beautiful color and is produced inexpensively for jewelry. Additionally, there is also a need for tools, jewelry, and the like obtained from such a synthetic single crystal diamond.

In addition to the above, there is also a need for a method designed to facilitate soldering of diamond to the shank or similar main part (body) of the tool when using diamond as a tool blade.

Accordingly, one of the objectives of the present invention is to provide a diamond tool superior to conventional diamond tools in terms of sharpness, abrasion resistance and quality stability.

Another objective of the present invention is to obtain a synthetic single-crystal diamond, which can have a reduced content of impurities or nitrogen and is inexpensively used for industrial purposes and will be excellent in resistance to abrasion and similar mechanical and physical properties, can have a beautiful color and can be easily soldered to the tool body, as well as in creating a method for the production of such a synthetic single-crystal diamond.

Another objective of the present invention is the creation of diamond jewelry using beautifully colored and inexpensive synthetic monocrystalline diamond.

Problem Solving Tools

The proposed diamond tool is made using single-crystal diamond, artificially synthesized under high pressure by the temperature gradient method and having a crystal containing an impurity in an amount of at least 3 ppm, preferably at least 0.1 ppm.

An artificial, synthetic diamond can have an admixture of nitrogen removed during the synthesis of diamond under high pressure by adding to the solvent a component that serves as a getter (getter) of nitrogen. However, this has an adverse effect on the diamond due to the appearance of inclusions, resulting in a deterioration in the quality of the crystal. The inventors of the present invention have proposed a method that can provide a crystal of good quality despite the addition of a nitrogen getter (Non-Patent Document 1). Thus, a high-purity synthetic diamond crystal (type IIa) having a nitrogen impurity controlled at a level of at least 3 ppm may not contain crystalline defects, stresses and the like caused by this impurity. This will lead to increased hardness and strength and other similar improved mechanical properties, as well as to a reduced variation in quality. In addition to this, except that there is a weak absorption due to nitrogen impurity in the ultraviolet region at 270 nm, there is no other absorption caused by the impurity. With a nitrogen content of at most 0.1 ppm, no absorption is also observed at 270 nm. Thus, a clear crystal can be obtained in the spectral region from ultraviolet to infrared.

The authors of the present invention studied the mechanical properties of high-purity synthetic diamond in more detail and found that there is a feature that is not observed either in natural diamonds or in ordinary synthetic diamonds.

Table 1 shows the results of measuring Knoop hardness of synthetic diamond crystals with various nitrogen contents in the (100) plane in the <100> and <110> directions. As shown in FIG. 1, in the (100) plane in the <100> direction, Knoop hardness improves as the nitrogen content decreases. A synthetic diamond crystal with a nitrogen content of at least 1 ppm provides a high hardness of at least 10,000 kg / mm ² . A synthetic diamond crystal with a nitrogen content of at least 3 ppm, according to measurements in the (100) plane in the <110> direction, does not give the usual Knoop print, which actually indicates its extreme hardness. Figure 2 shows the results of measuring Knoop hardness on the (100) plane for each orientation in this plane of a synthetic diamond crystal IIa with a nitrogen content of 0.1 ppm, a diamond crystal Ib with a nitrogen content of 60-240 ppm and a natural crystal diamond Ia (containing approximately 1000 ppm of aggregated nitrogen as an impurity).

Table 1 Sample No. Nitrogen concentration (ppm) Knoop hardness (kg / mm ² ) (100) <100> (100) <110> IIa-01 0 11779 * IIa-02 0 12898 * IIa-03 0.04 10554 * IIa-04 0.04 11396 * IIa-05 0.04 11950 * IIa-06 0.05 9867 * IIa-07 0.36 10027 * IIa-08 0.5 10401 * IIa-09 1.7 8474 * IIa-10 2.6 9428 * Ib-01 60 8607 8475 Ib-02 88 9669 7401 Ib-03 235 9479 8075 * Not measurable due to the lack of an imprint

While natural diamonds and typical synthetic diamonds on the (100) face showed greater hardness in the <100> direction than in the <110> direction, diamonds with an impurity content of at most 3 ppm show the opposite trend. In particular, in the <110> direction, it is not possible to create a print with a Knoop indenter, thereby showing that the diamond is extremely hard. This is probably due to the fact that the synthetic diamond crystal IIa has a significantly smaller amount of impurities and defects, which make it possible to initiate deformations when the indenter is pressed into the crystal. It should be noted that in the case of impurity contents exceeding 3 ppm, this trend was not observed, but instead a trend was established that was similar to the trend for a natural diamond crystal and a synthetic diamond crystal Ib.

The proposed diamond tool can be made in the form of a high-precision cutting tool. The low hardness diamond described above having high hardness can provide a highly abrasion resistant ultra-precise cutting tool.

In addition, the proposed diamond tool can be made in the form of a microtome knife, a surgical knife, or a similar diamond knife. The low nitrogen diamond described above having high hardness and reduced defects can provide an excellent sharp diamond knife.

Similarly, the proposed diamond tool can be made in the form of tools for drawing lines, diamond tools (diamond needles) or the like. The low nitrogen diamond described above, having high hardness and reduced defects, can provide a line tool that is excellent in abrasion resistance and has a limited number of defects.

In addition, the proposed diamond tool can be made in the form of a tool for sharpening (the correct tool). The low nitrogen diamond described above, having high hardness and reduced defects, can provide a sharp sharpening tool with excellent abrasion resistance.

Based on the above experimental data, a synthetic diamond with an impurity content of at least 3 ppm, preferably at most 0.1 ppm, and with a reduced number of defects was used to make the tool. The impurity content can be reduced by using a source of high purity carbon and a Fe-Co based solvent and adding a nitrogen getter such as Ti to this solvent. In addition, linear defects or dislocations can be removed by using a crystal cut from a diamond crystal with a low density of defects as a seed.

The proposed synthetic single crystal diamond according to one aspect of the invention is synthesized under ultrahigh pressure at high temperature by the temperature gradient method, and it is characterized in that it has a crystal containing nickel introduced by atomic substitution.

The present invention uses a solvent having a high nickel content. Accordingly, this leads to a pale green color of the synthetic single-crystal diamond. In addition, since synthetic single-crystal diamond contains a reduced number of substituting nitrogen atoms, it can have reduced stresses in the crystal, which contributes to an increase in hardness and resistance to abrasion.

A decrease in the amount of nitrogen allows the diamond to be resistant to degradation due to oxidation caused by excessive heating of the diamond when it is processed into a tool blade or the like. Thus, an increased sharpness of the blade can be provided.

Preferably, nickel is contained in an amount of from 0.01 ppm to 10 ppm. A nickel content of at most 10 ppm does not adversely affect synthetic single crystal diamond with respect to hardness, resistance to abrasion and sharpness and, in addition, allows the diamond to exhibit a beautiful pale green color. Nickel contents in excess of 10 ppm cause excessive stress, and the function and effect of the present invention hardly appear, and, in addition, the diamond becomes dark in color. A nickel content of less than 0.01 ppm is preferred for synthetic single crystal diamond with respect to strength and other similar mechanical and physical characteristics. However, the production of such a diamond is expensive and time consuming. This is due to the fact that the use of a nickel-containing solvent allows the crystal to grow at a much higher rate. In addition, in order to achieve a pale green color, the diamond preferably contains at least 1 ppm of nickel.

Nitrogen is preferably contained in an amount of from 0.01 ppm to 3 ppm. The specified range allows you to effectively increase the hardness, resistance to abrasion and the like, and, in addition, provides a reduced cost of production.

The present invention, which is applied to a synthetic single crystal diamond used for a tool, can exhibit to a large extent such an effect as increased hardness.

If the proposed synthetic single-crystal diamond is used as a tool blade, and solder is used to solder this diamond to the shank (or the main body of the tool), then it is preferable to use titanium-containing activated solid solder, since it allows soldering the diamond at a relatively low temperature.

The proposed synthetic monocrystalline diamond containing nickel and having an extremely low nitrogen content does not show a dark yellow color, but a pale green color. In this regard, it is preferable to use such a proposed diamond as jewelry.

When the proposed synthetic single crystal diamond is used for a tool, this tool can be a very hard and abrasion resistant tool, and thus a long service life and the like are effectively ensured. Such a tool may be a cutting tool, a sharpening tool and the like. In addition, when the proposed synthetic single crystal diamond is used in jewelry, a pale green color significantly increases the cost of diamond jewelry.

In the proposed method for the synthesis of single-crystal diamond, it is synthesized under ultrahigh pressure at high temperature by the temperature gradient method, and the method is characterized by the use of a solvent containing at least one of iron and cobalt, at least 36 wt.% Nickel, 1-2 wt. % titanium and 3-5.5 wt.% graphite.

In the present invention, the solvent contains about 1-2 wt.%, Preferably about 1.5 wt.%, Titanium, which reacts with nitrogen contained as an impurity, and thus prevents the adverse entry of nitrogen into the diamond crystal. In addition, despite the fact that copper or a similar element is not added, which prevents the occurrence of inclusions, titanium will not penetrate into the diamond crystal as an inclusion. This is presumably due to the fact that the solvent contains approximately 36% by weight, preferably approximately 40% by weight, of nickel, which is in the Periodic Table practically adjacent to copper. Nickel is included in the diamond crystal as a substitute atomic impurity in an amount of at least 10 ppm.

The seed face of the seed crystal is preferably the (100) plane, as this allows for preferred crystal growth. In addition, synthetic monocrystalline diamond is preferably synthesized at a temperature of 1380 ± 25 ° C, since such a temperature can facilitate the introduction of nickel into the diamond crystal accordingly as a substitute atomic impurity.

Synthetic monocrystalline diamond is preferably synthesized at a rate of 3.9-4.7 mg / h (h), since such a rate can contribute to cost-effectiveness and also facilitate the introduction of nickel into the diamond crystal accordingly as a substitute atomic impurity.

A synthetic monocrystalline diamond proposed in another aspect of the invention is synthesized under ultrahigh pressure at high temperature by a temperature gradient method and has a crystal containing boron and nickel introduced by atomic substitution.

The present invention makes it possible to use a solvent containing an increased amount of nickel, and in addition, titanium or a similar nitrogen getter and boron are added to it. This allows a synthetic single-crystal diamond to contain a reduced amount of substituting nitrogen atoms, and instead contain boron and nickel substituent atoms.

Mainly synthetic single-crystal diamond can be obtained, which has reduced stresses in the crystal due to the reduced nitrogen content and has significant hardness and considerable resistance to abrasion due to the boron contained therein. The reduced nitrogen content allows the diamond to be resistant to degradation due to oxidation caused by excessive heating of the diamond when it is processed into a tool blade or the like. Thus, an increased sharpness of the blade can be provided. In addition, synthetic single crystal diamond containing boron will also be electrically conductive. In addition, synthetic single crystal diamond, which contains boron and nickel, has a pale blue-green color.

Preferably, boron is contained in an amount of 1-300 ppm. A boron content of 300 ppm or less allows the metal to be captured from the solvent into the diamond crystal as an impurity in a limited amount, which contributes to excellent abrasion resistance. A boron content in excess of 300 ppm makes the crystal brittle as well as dark in color and thus unsuitable for practical use. A boron content of one ppm or more, in particular more than 5 ppm, allows the diamond to have a corresponding pale blue-green color, and also have an appropriate level of electrical conductivity.

Nickel is preferably contained in an amount of 0.01-10 ppm. Nickel, contained in an amount of 10 ppm or less, allows the diamond to have a pale blue-green color and, together with the action of titanium or a similar nitrogen getter, serves to relatively reduce the amount of nitrogen entering the diamond crystal as a result of atomic substitution, and, thus, provides a single-crystal diamond, acceptable in hardness, resistance to abrasion and sharpness. Nickel, contained in an amount exceeding 10 ppm, is the cause of high stresses and, in addition, gives the diamond a dark color. Nickel, contained in an amount of less than 0.01 ppm, increases the time and cost of diamond production. In addition, nickel is preferably contained in an amount of at least 1 ppm, since it can act together with the simultaneously present boron to give a pale blue-green color.

Preferably, nitrogen is contained in an amount of 3 ppm or less. Such an amount allows the diamond crystal to have reduced stresses, providing acceptable hardness, resistance to abrasion and sharpness.

The present invention, when applied to a synthetic single crystal diamond used as a tool, can detect superior abrasion resistance or a significant similar effect.

If the proposed synthetic single-crystal diamond is used as a tool blade and a solder is used to solder the diamond to the shank (or the main part of the tool), it is preferable to use a titanium-containing activated solder because it allows the diamond to be brazed at a relatively low temperature.

Since nitrogen is essentially excluded from the composition of the proposed synthetic single-crystal diamond, while it contains boron and nickel, such a diamond has a pale blue-green color. Preferably, such a diamond is used as jewelry.

When the proposed synthetic single crystal diamond is used for a tool, this tool can be a very hard and abrasion resistant tool, and thus, an increase in service life and the like is effectively provided. Such a tool may be a cutting tool, a sharpening tool and the like. In addition, when the proposed synthetic single crystal diamond is used in jewelry, a pale green color significantly increases the cost of diamond jewelry.

In a method for the synthesis of single-crystal diamond proposed in another aspect of the invention, it is synthesized under ultrahigh pressure at high temperature using the temperature gradient method, and the method is characterized by the use of a solvent containing at least one of iron and cobalt, at least 36 wt.% Nickel, 1 -2 wt.% Titanium, 0.1-0.2 wt.% Boron and 3-5.5 wt.% Graphite.

In the present invention, the solvent contains about 1-2 wt.%, Preferably about 1.5 (± 10) wt.%, A nitrogen getter (titanium as an example), which reacts with nitrogen contained as an impurity, and thus prevents adverse entry of nitrogen into the diamond crystal. In addition, although copper or a similar element that prevents inclusions is not added, titanium or a similar nitrogen getter will not enter the diamond crystal as an inclusion. This is presumably due to the fact that the solvent contains approximately 36% by weight, preferably approximately 40% by weight, of nickel, which occupies a position practically adjacent to copper in the Periodic Table. Nickel is included in the diamond crystal as a substitute atomic impurity in an amount of at least 10 ppm. In addition, boron, which is contained in the solvent in an amount of about 0.1-0.2 wt.%, Preferably about 0.15 wt.%, Is also included in the diamond crystal as a substitute atomic impurity in an amount of at least 300 h / million

In addition, the seed face of the seed crystal is preferably the plane (100) of the diamond crystal, since this allows the boron to be evenly distributed and the diamond crystal to be grown in a preferred manner.

In addition, synthetic monocrystalline diamond is preferably synthesized at a temperature of 1350 ± 30 ° C, since this temperature allows a substitute atomic impurity, i.e. nickel and boron, enter the diamond crystal accordingly.

In addition, synthetic single-crystal diamond is preferably synthesized at a rate of 3.1-3.8 mg / h (hour), since such a rate can contribute to an increase in efficiency from a cost point of view, and also allows a substitute atomic impurity, i.e. nickel and boron, enter the diamond crystal accordingly.

The proposed diamond jewelry is made of the above synthetic single crystal diamond.

The results of the invention

When a single-crystal diamond is used for the manufacture of a tool, a synthetic diamond having a small nitrogen content as an impurity allows this tool to be a diamond tool having high hardness and a reduced number of defects, and thus more surpass conventional diamond tools in terms of sharpness and resistance to abrasive wear and quality stability.

The proposed synthetic single crystal diamond can be characterized by the presence in it of a limited number of substituting nitrogen atoms. This can contribute to the reduction of stresses in the crystal and increase the hardness and resistance to abrasion, allowing you to make the preferred tool.

In addition, the solvent containing Nickel, allows you to synthesize diamond with an increased growth rate and, thus, to obtain a diamond with reduced costs. In addition, since the proposed synthetic single crystal diamond may have a pale green color, this gives it a significantly higher cost in jewelry.

In addition, the proposed synthetic single crystal diamond has a low content of nitrogen contained in the crystal as a substitute atomic impurity, and contains an appropriate amount of boron. As such, the proposed diamond may have excellent abrasion resistance. In addition, the proposed diamond can also provide a synthetic single crystal diamond, excellent, for example, in terms of resistance to abrasive wear and, thus, suitable for use as a tool blade. In addition, the proposed diamond can provide a sufficiently electrically conductive synthetic single crystal diamond. In addition, the proposed synthetic single-crystal diamond may contain nickel and boron in the crystal as a substitute atomic impurity and, thus, have a pale blue-green color, which is of high value as a jewelry. In addition, the above-described synthetic single crystal diamond can be obtained in an inexpensive manner.

Brief Description of the Drawings

Figure 1 shows the Knoop hardness of synthetic diamond in the (100) plane along the <100> direction.

Figure 2 presents Knoop hardness of different types of diamond in the (100) plane for each orientation in this plane.

Figure 3 is a General view of the installation for the synthesis of synthetic single crystal diamond according to the third example of the present invention.

Fig. 4A is a side view of a blade of a tool using a synthetic single crystal diamond according to a third example of the present invention.

Fig. 4B is a plan view of the blade of the tool shown in Fig. 4A.

5 is a perspective view of a sharpening tool using a synthetic single crystal diamond according to a third example of the present invention.

Fig.6 is a General view of the installation for the synthesis of synthetic single crystal diamond according to the fourth example of the present invention.

Fig. 7A is a side view of a blade of a tool using a synthetic single crystal diamond according to a fourth example of the present invention.

Fig. 7B is a plan view of the blade of the tool shown in Fig. 7A.

Description of Reference Positions

11 - carbon source; 12 - metal solvent; 13 - seed crystal; 14 - insulating material; 15 - graphite heater; 16 - working medium under pressure; 21 - a blade of synthetic single crystal diamond; 22 - a layer of solder; 23 - end part of the shank; 31 - a tool for sharpening from synthetic single crystal diamond; 32 - sintered part.

BEST MODES FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described using examples.

Example 1

For the synthesis of a diamond crystal, the temperature gradient method at high pressure was used. More specifically, high-purity graphite was used as the carbon source material, and a Fe-Co solvent was used as the solvent with 1.5 wt.% Ti added thereto as a nitrogen getter. A crystal with a low defect density was used as a seed crystal, with the (001) plane serving as a seed face, and a pressure of 5.5 GPa was applied at a temperature of 1350 ° C for 70 hours to synthesize a high-purity diamond IIa single crystal, mass approximately 0.8 carats.

The resulting diamond crystal was colorless (achromatic) and transparent, and there was essentially no absorption in the ultraviolet, visible, and infrared spectral regions with nitrogen or a similar impurity, and the crystal was a high purity crystal IIa with an impurity content of 0.1 ppm or less. In addition, as established using a polarizing microscope, the diamond crystal essentially had no internal stresses, and, as established by x-ray topography, the diamond crystal essentially had no crystal defects.

The diamond crystal obtained as described above was used for the manufacture of the cutting tool as follows: the diamond crystal was processed so that it had a length of 3 mm, a width of 1 mm and a thickness of 1 mm and was soldered to the shank of the cutting tool, preferably using titanium-containing, activated solder, since it allows soldering a diamond crystal at a relatively low temperature and thereby ensures that the surface of a single-crystal diamond is less than a thermal damaged. In addition, the diamond material is soldered to the shank with a layer of solder, preferably having a thickness of 100 μm or more. This allows the resulting cutting tool to have a reduced residual stress in the end portion caused by soldering the crystal to the shank. In addition, in order to provide a surface for soldering a single-crystal diamond material, the (100) plane was chosen as the upper and lower faces. Subsequently, a cutting tool was made having a diamond blade with a cutting edge having a radius R of 10 μm and an angle of 45 °.

If the orientation of the plane of the cutting edge corresponds to the plane (110), this contributes to the grinding of the material and, thus, allows the tool to have a cutting edge with increased strength and sharpness. In addition, in the manufacture of the cutting tool, a skyf was used, having free abrasive diamond grains on a cast iron part, rotating at high speed. The cutting tool thus obtained had a blade with a cutting edge, which, according to observations, did not contain small cracks with a size of several microns or less. This cutting tool (cutter) was mounted on a precision lathe rotating the workpiece at a speed of 800 revolutions per minute (rpm), while the tool was advanced at a speed of 0.3 μm / rev to provide a cut of 1 μm in the metal Ni part, covering the surface of the mold for injection molding. No traces formed as the tool was fed were observed, and as a result, a mirror-polished surface was obtained with high accuracy.

Example 2

With the exception that the getter of nitrogen or Ti was added in an amount of 1.5 wt.%, A method similar to that described in Example 1 was used to synthesize a high purity diamond IIa single crystal weighing approximately 0.8 carats. The obtained diamond crystal was slightly yellow in that to some extent, it was absorbed in the ultraviolet and visible regions of the spectrum due to an isolated nitrogen substitute impurity contained in an amount of approximately 2.8 ppm When observed in a polarizing microscope, it was confirmed that the diamond crystal essentially had no internal stresses, and when examined by x-ray topography, it was confirmed that it essentially had no crystal defects.

The diamond crystal thus obtained was used to make a cutting tool in a manner similar to that described in Example 1. The cutting tool had a blade with a cutting edge that, according to observations, did not contain small cracks of a few microns or less in size. This cutting tool (cutter) was mounted on a precision lathe and conditions similar to those described in Example 1 were selected to cut the metal Ni-th part covering the surface of the injection mold. No traces formed during the supply of the tool were observed, and as a result, a mirror-polished surface was obtained with high accuracy.

Comparative Example 1

Except that a nitrogen getter was not used, a method similar to that described in Example 1 was used for diamond synthesis. The obtained diamond was a one carat Ib crystal containing nitrogen as an impurity and having a yellow color. According to estimates made using the infrared absorption spectrum, nitrogen was present in an amount of approximately 60 ppm. This synthetic diamond crystal Ib was used to produce an ultra-high precision cutting tool in a manner similar to that described in Example 1. The resulting cutting tool was worse than the tool according to Example 1 in terms of sharpness and abrasion resistance.

Reference Example 2

Natural diamond Ia was used to manufacture the cutting tool in a manner similar to that described in Example 1. Probably due to the fact that the cutting tool had a defective blade, it was not sharp and also caused significant abrasion when cutting the workpiece.

Example 3

The present invention will be described further in Example 3.

Synthesis

First, the synthesis of diamond will be described.

Figure 3 shows the installation for the synthesis of diamond in this example. In FIG. 3, reference numerals 11, 12, 13, 14, 15, and 16 denote a carbon source, a metal solvent, a seed crystal, an insulating material, a graphite heater, and a pressure medium, respectively.

The carbon source 11 was graphite. The metal solvent 12 contained 42 wt.% Nickel as the main component and 1.5 wt.% Titanium as a nitrogen getter.

The rest was 53 wt.% Iron, 5 wt.% Cobalt and 4.5 wt.% Graphite, and all of the above were in the form of high-purity powders having a grain size of 50-100 microns. It should be noted that iron and cobalt were mixed in a ratio that allowed wide variation. In addition, in the case of a seed crystal, the (100) plane of the abrasive grains of synthetic diamond served as a seed face.

To synthesize 10 pieces of single-crystal diamond weighing 1.5 carats, a pressure of 5.5 GPa was applied at 1380 ° C and a carbon source and a seed crystal having a temperature difference (gradient) of 30 ° C were used for 70 hours. It should be recalled that one carat corresponds to 200 mg. The obtained single-crystal diamond had a large plane (100). Measurements were made of the absorption in the ultraviolet, visible and infrared regions of the spectrum, and it was confirmed that it contained 3 ppm or less nitrogen and 10 ppm or less nickel. It should be noted that since the diamond had a pale green color, the nickel content was estimated to be at least 1 ppm, which corresponds to the concentration at which the diamond takes on a pale green color. It was found that the diamond contained at least 1.5-2 ppm of nickel.

In addition, as established using a polarizing microscope, the diamond essentially had no internal stresses. In addition, as established by x-ray topography, the diamond essentially had no crystalline defects.

Tool blade making

The synthetic diamond in this example was used to make a tool blade as described below.

The above synthetic diamond was processed to obtain a material from synthetic single crystal diamond having a length of 5 mm, a width of 1 mm and a thickness of 1 mm and intended for a blade. This material was soldered to the shank using titanium-containing activated solder, since it allows the material to be soldered at a relatively low temperature and therefore allows a single crystal diamond to have a less thermally damaged surface.

In addition, in order to protect the cutting tool from the presence of thermal stresses remaining therein, the solder was applied with a layer preferably having a thickness of 100 μm or more. In addition, in order to provide a surface for soldering this material to the shank, a plane (100) was specified as the upper and lower surfaces.

Then, a rapidly rotating grinding device was used to form the blade of the cutting tool (cutter) having a cutting edge with a radius R of 100 μm, a taper angle of 30 °, and a tilt angle of 20 °. It was confirmed that the cutting edge did not have cracks of 1 μm or more in size, and thus was sharp.

The cutter is shown in figa and 4B. In these figures, reference numeral 21 denotes a synthetic single crystal diamond blade; R is the radius of the cutting edge; α denotes a slope angle of 20 °; and β denotes an edge angle (taper angle), which is 30 °. Reference numeral 22 denotes a layer of titanium-containing solder. Reference numeral 23 denotes the end portion of the shank.

This cutter was attached to a high precision lathe. The part to be cut had a diameter of 5 mm and it was rotated at a speed of 3000 rpm, while the tool was fed at a speed of 0.3 μm / r to cut 0.1 μm in a nickel coating covering the surface of a metal mold for casting pressure, to obtain a mirror-polished surface with high accuracy.

When an ordinary synthetic single-crystal diamond was used to make the tool and such tools were used in the cutting mode, these tools withstood 58 treatments, while in the case of using the present invention for the manufacture of the tool and using such tools in the same cutting mode, the tools withstood 93 treatments. As a result, it was confirmed that in this example a synthetic single crystal diamond was obtained, suitable as a material for a tool blade.

Sharpening Tool Making

The synthetic single crystal diamond according to this example was used to make a sharpening tool as described below.

The rough diamond synthesized using the above-described apparatus as described above was split along the (111) plane so that its thickness was 0.8 mm and laser cut so as to obtain plate-shaped material having a length of 3 mm and a width of 0.8 mm and a thickness of 0.8 mm. Three such plates were placed in a sintered powder containing nickel as the main component, and sintered.

It should be noted that the plate was obtained having an elongated part of the surface corresponding to the split plane (111) and the laser cutting plane (110), and a sharpening surface corresponding to the plane (211). Accordingly, the end surface of the test specimen formed from this plate will be a sharpening surface and accordingly will be parallel to the grinding direction <110>.

This sharpening tool is shown in FIG. In this figure, reference numeral 31 denotes a single-crystal synthetic diamond material in the form of a plate, and reference numeral 32 denotes the sintered portion around it.

The sharpening tool reciprocated using the SN80N8V51S whetstone (manufactured by Noritake, 405 × 50 × 127 mm), having a circular speed of 1500 rpm, to perform a 0.1 mm cut at each pass, while it was fed 0.5 mm / reverse under the conditions of the method using a fluid (cutting lubricant for grinding: Noritake cool NK88) for 20 minutes in the direction parallel to the axis of rotation of the grindstone to sharpen the workpiece, while the degree of abrasive wear was measured.

In addition, under the same conditions, the degree of abrasive wear of the sharpening tool was also measured using conventional synthetic single crystal diamond. The results shown in table 2 indicate that in this example a synthetic single-crystal diamond was obtained, providing a significantly lower degree of abrasive wear compared to conventional synthetic single-crystal diamond, and, thus, it is suitable as a material for a sharpening tool .

table 2 Plane orientation Grinding direction The degree of abrasive wear (10 ^-3 mm ³ ) Regular product (211) <110> 13.5 The present invention (211) <110> 9.8

Jewelry Application

In the end, a synthetic single crystal diamond according to this example used for jewelry will be described.

A 1.55-carat diamond synthesized using the above-described apparatus in the above-described manner was treated with skyfa so that it acquired a rounded diamond cut.

The 0.45-carat diamond obtained for jewelry did not contain any chips and cracks and was a greenish diamond.

Example 4

The present invention will be described further in the fourth example.

Synthesis

First, in this example, the diamond was synthesized as described below.

Figure 6 shows the installation for the synthesis of diamond used in this example. In this figure, reference numerals 11, 12, 13, 14, 15 and 16 indicate respectively a carbon source, a metal solvent, a seed crystal, an insulating material, a graphite heater, and a pressure medium.

The carbon source 11 was graphite. The metal solvent 12 contained 42 wt.% Nickel and 0.15 wt.% Boron as the main components and 1.5 wt.% Titanium as a nitrogen getter. The rest was 46.85 wt.% Iron, 5 wt.% Cobalt and 4.5 wt.% Graphite, and all of the above were in the form of high-purity powders having a grain size of 50-100 microns. It should be noted that iron and cobalt were mixed in a ratio that allowed wide variation. In addition, in the case of a seed crystal, the (100) plane of the abrasive grains of synthetic diamond served as a seed face.

To synthesize 10 pieces of single-crystal diamond weighing 1.2 carats, a pressure of 5.5 GPa was applied at 1350 ° C and a carbon source and a seed crystal having a temperature difference of 30 ° C were used for 70 hours.

The obtained single-crystal diamond had a large plane (100). Absorbance was measured in the ultraviolet, visible and infrared regions of the spectrum, and it was confirmed that it contained 3 ppm or less of nitrogen, 50 ppm of boron and 10 ppm or less of nickel. The diamond was estimated to have a nickel content of at least 1 ppm because the diamond crystal was a pale blue-green, a mixture of blue that was attributed to boron and green that was attributed to nickel.

In addition, as established using a polarizing microscope, the diamond essentially had no internal stresses. In addition, as established by x-ray topography, the diamond essentially had no crystalline defects. In addition, single crystal diamond has also been measured with respect to electrical resistance. The crystal had a resistivity of 10-100 Ohm · cm, indicating that it had sufficient electrical conductivity.

Tool blade making

The synthetic diamond in this example was used to make a tool blade as described below.

The above-described synthetic single-crystal diamond was processed to obtain a material from synthetic single-crystal diamond having a length of 5 mm, a width of 1 mm and a thickness of 1 mm and intended for a blade (cutting insert) of a diamond end mill. This material was soldered to the shank using activated titanium-containing solder, since it allows the material to be soldered at a relatively low temperature and therefore allows single-crystal diamond to have a less thermally damaged surface.

In addition, in order to protect the cutting tool from the presence of thermal stresses remaining therein, the solder was applied with a layer preferably having a thickness of 100 μm or more. In addition, in order to provide a surface for soldering this material to the shank, a plane (100) was specified as the upper and lower surfaces.

Then, a rapidly rotating grinding device was used to form a cutting tool blade having a cutting edge with a radius R of 100 μm, a taper angle of 30 °, and a tilt angle of 20 °. It was confirmed that the cutting edge did not have cracks of 1 μm or more in size and thus was sharp.

This blade is shown in FIGS. 7A and 7B. In these figures, reference numeral 21 denotes a synthetic single crystal diamond blade; R is the radius of the cutting edge; α denotes a slope angle of 20 °; and β denotes an edge angle (taper angle), which is 30 °. Reference numeral 22 denotes a layer of titanium-containing solder. Reference numeral 23 denotes the end portion of the shank.

This cutting tool was attached to a high precision lathe. The workpiece to be cut had a diameter of 5 mm and it was rotated at a speed of 3000 rpm, while the tool was fed at a speed of 0.3 μm / r to cut 0.1 μm in a nickel coating covering the surface of a metal mold for casting pressure, to obtain a mirror-polished surface with high accuracy.

When a conventional synthetic single-crystal diamond was used to make the tool and such tools were used in the cutting mode, the tools withstood 58 treatments, while in the case of using the present invention for the manufacture of the tool and using such tools in the same cutting mode, the tools withstood 85 treatments. As a result, it was confirmed that in this example a synthetic single crystal diamond was obtained, suitable for use as a material for a tool blade.

According to this example, a synthetic diamond single crystal having sufficient electrical conductivity is obtained. In this regard, if the crystal is attached to equipment capable of automatically replacing the tool, then the electric resistance can be measured in this tool to determine whether it comes in contact with the object being cut or the like. Due to this, tool management as well as production quality management can be simplified.

Jewelry Application

In the end, a synthetic single-crystal diamond used according to this example for jewelry will be described.

Synthetic single-crystal diamond weighing 1.2 carats, synthesized using the above setup in the manner described above, was treated with skif so that it acquired a rounded diamond cut.

The 0.36 carat diamond obtained for jewelry did not contain chips and cracks at all and was a greenish diamond.

Each embodiment of the present invention described above may be appropriately combined with any other. In addition, although the present invention has been described and illustrated here in detail, it should be clearly understood that this is done only as an illustration and example and should not be construed as limiting the nature and scope of the present invention, limited only by the terms of the attached claims.

Industrial applicability

The present invention is effectively applicable to diamond tools, synthetic single crystal diamonds, methods for synthesizing single crystal diamonds and diamond jewelry.

Claims (26)

1. A diamond tool made using single-crystal diamond artificially synthesized under high pressure using a temperature gradient method, characterized in that said diamond has a crystal containing nitrogen in an amount of not more than 3 ppm, and the tool has a blade, the end of which has an orientation in the plane that is the (110) plane, the Knoop hardness in the (100) plane in the <110> direction is higher than in the <100> direction. 2. The diamond tool according to claim 1, in which said crystal contains said nitrogen in an amount of not more than 0.1 ppm. 3. The diamond tool according to claim 1, which is one of the ultra-high precision cutting tool, microtome knife, diamond knife, diamond cutter, line drawing tool and sharpening tool. 4. The diamond tool according to claim 1, in which a titanium-containing activated solder is used to attach the said diamond to the main body of the tool (22). 5. A diamond tool made using single-crystal diamond artificially synthesized under high pressure using a temperature gradient method, characterized in that said diamond has a crystal containing nitrogen in an amount of not more than 3 ppm, and the tool has a blade, the end of which has an orientation in a plane that is a (110) plane, and said crystal also contains nickel, wherein the Knoop hardness in the (100) plane in the <110> direction is higher than in the <100> direction. 6. The diamond tool according to claim 5, in which said nickel is contained in an amount of at least 0.01 ppm and not more than 10 ppm. 7. A diamond tool according to claim 5, in which a titanium-containing activated solder is used to attach the said diamond to the main body of the tool (22). 8. A diamond tool made using single-crystal diamond artificially synthesized under high pressure using a temperature gradient method, characterized in that said diamond has a crystal containing nitrogen in an amount of not more than 3 ppm, and the tool has a blade, the end of which has an orientation in the plane that is the (110) plane, and said crystal also contains boron and nickel, moreover, the Knoop hardness in the (100) plane in the <110> direction is higher than in the <100> direction. 9. The diamond tool of claim 8, in which said boron is contained in an amount of at least 0.01 ppm and not more than 300 ppm. 10. The diamond tool of claim 8, wherein said nickel is contained in an amount of at least 0.01 ppm and not more than 10 ppm. 11. A diamond tool according to claim 8, in which a titanium-containing activated solder is used to attach the said diamond to the main body of the tool (22). 12. A diamond jewelry product made using single-crystal diamond artificially synthesized under ultrahigh pressure by a temperature gradient method, characterized in that said diamond has a crystal containing nitrogen in an amount of not more than 3 ppm and nickel as a substitute atom, the hardness being according to Knup said diamond in the (100) plane in the <110> direction is higher than in the <100> direction. 13. The diamond jewelry product of claim 12, wherein said nickel is contained in an amount of at least 0.01 ppm and not more than 10 ppm. 14. The diamond jewelry product of claim 12, containing nitrogen in an amount of at least 0.01 ppm and not more than 3 ppm. 15. The diamond jewelry product of claim 12, also containing boron as a substitute atom. 16. The diamond jewelry product of claim 15, wherein said boron is contained in an amount of at least 0.01 ppm and not more than 300 ppm. 17. The method of synthesis of single-crystal diamond under ultrahigh pressure at high temperature by the temperature gradient method, characterized in using a solvent consisting of at least one of iron and cobalt, at least 36 wt.% Nickel, at least 1 wt.% And not more than 2 wt.% Titanium and at least 3 wt.% And not more than 5.5 wt.% Graphite. 18. The method according to claim 17, wherein a seed crystal is used, wherein the seed face of the seed crystal (13) is a plane (100) of a diamond crystal. 19. The method according to 17, in which said single-crystal diamond is synthesized at 1380 ± 25 ° C. 20. The method according to 17, in which the said single-crystal diamond is synthesized at a speed of at least 3.9 mg / h and not more than 4.7 mg / h. 21. The method of synthesis of single-crystal diamond under ultrahigh pressure at high temperature by the temperature gradient method, characterized in using a solvent consisting of at least one of iron and cobalt, at least 36 wt.% Nickel, at least 1 wt.% And not more than 2 wt.% Titanium, at least 0.1 wt.% And not more than 0.2 wt.% Boron and at least 3 wt.% And not more than 5.5 wt.% Graphite. 22. The method according to item 21, in which a seed crystal is used, wherein the seed face of the seed crystal (13) is a plane (100) of a diamond crystal. 23. The method according to item 21, in which the said single-crystal diamond is synthesized at 1350 ± 3 ° C. 24. The method according to item 21, in which the said single-crystal diamond is synthesized at a speed of at least 3.1 mg / h and not more than 3.8 mg / h Priority on points: 10/10/2003 according to claims 1-4; 09/28/2004 according to claims 5-24.

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