WO2022025800A1 - Chromium tetraboride-based materials and methods for producing same - Google Patents

Abstract

The invention relates to the field of synthesizing novel materials and can be used for manufacturing a cutting tool, cutting elements for a rock-cutting tool (drill bits), and other structural elements and mechanisms having surfaces that require high wear resistance.

Description

Materials based on chromium tetraboride and methods for their preparation

The invention relates to the field of synthesis of new materials and can be used for the manufacture of cutting tools, cutters of rock cutting tools (drill bits) and other structural elements and mechanisms that require high wear resistance of surfaces. Drill bit cutters made of a layer of carbide material and a layer of diamond (PDC) are widely used.

Chromium borides, due to their crystal structure, have a high hardness, which allows them to be used in the manufacture of wear-resistant products. There is a wide variety of experimentally known phases of chromium borides. The hardest phase is chromium tetraboride (CrB ₄ ), which has a theoretical Vickers hardness limit of about 47 GPa and a density of 4.29 g/cm ³ .

In addition to high hardness, materials used to make wear-resistant products, in particular drill bit cutters or product coatings, must also have good flexural (shear modulus) and compressive (compression modulus) strength, which also ensures high wear resistance and the ability to use such products in abrasive wear conditions. In this case, knowing the structure of the material/composite, one can calculate the universal (optimal) ratios between its effective elastic moduli. The combination of high heat resistance and wear resistance of materials makes it possible to ensure the operation of products made from them at high temperatures in the area of contact with the material being processed.

The most widely used materials due to their high wear resistance are materials based on tungsten carbide. Due to the shortage of tungsten, other carbide materials are widely studied, which include carbides or borides of various metals and their combinations. Some of them have high hardness but less bending strength, or good bending strength but less hardness and wear resistance.

Known carbide materials and products based on them, which include chromium borides to improve, for example, the heat resistance of such materials.

A drilling tool is known, at least part of the element of which contains triple borides, which include, in particular, chromium, and a method for the synthesis of such elements (application for invention US 20140262542, publ. 18.09.2014, IPC: E21B 10/567, B24D 8 /00). It is noted that triple borides provide better sintering and mechanical properties of the material. Common features with the claimed materials is the content of chromium borides in the composition. However, the crystal structure of ternary borides can vary depending on the composition and content of the components, which will have a significant impact on the hardness and elastic moduli of the material. The introduction of additional elements into the structure will also reduce the high thermal stability characteristic of chromium borides.

Common features of the known and claimed drilling tool is the manufacture of elements (plates) from a material containing chromium borides. However, the above disadvantages for the known material are also characteristic of products made from this material.

Known wear-resistant and corrosion-resistant coating of many thin overlapping plates that contain particles of chromium boride dispersed in a metal matrix, while the content of chromium boride is less than 30% (patent US6007922, publ. 28.12.1999, IPC: B22F7/04, B05D 5/ 00). Common features with the claimed materials is the content of chromium boride. However, firstly, the well-known technical solution does not indicate which chromium borides are included in the composition of the material, and secondly, the execution of the material in the form of a plurality of overlapping plates, which contain only 30% chromium borides or less, does not provide high hardness, heat resistance , wear resistance and high values of all effective moduli of elasticity of such material.

From the same source, a method for obtaining a wear-resistant and corrosion-resistant coating is known, which includes applying an initial powder mixture containing at least two components (chromium and a boron-containing alloy) to the substrate, followed by heating the applied coating to a temperature sufficient to conduct a diffusion reaction between the components. Common features are the use of a boron-containing alloy (in the case of the claimed invention, chromium diboride (CrB ₂ )) and the synthesis of the material at high temperature. However, the use of chromium powder and boron-containing powder on the right as the initial mixture makes it difficult to form chromium tetraboride in the composition of the material due to the lack of boron, and the low content of chromium borides does not allow obtaining a material with high hardness, heat resistance and wear resistance.

The closest analogue (prototype) of the claimed invention is the known material (Wang S. et al. Crystal structures, elastic properties, and hardness of high-pressure synthesized CrB ₂ and CrB ₄ // J. Superhard Mater. 2014. Vol. 36. P. 279–287), the phase composition of which includes 45% CrB ₄ , 50% CrB ₂ , and 5% boron nitride. Common features of the claimed and known material are the content of chromium tetraboride and chromium diboride. However, boron nitride enters the composition of this material in the process of thermobaric synthesis of samples. At the same time, it does not provide binding between particles of chromium borides, which, at high hardness of the samples, does not make it possible to ensure the ratio of elastic moduli, which simultaneously characterize high flexural and compressive strength, and therefore high wear resistance of such a material will not be ensured. Known material is also characterized by low hardness, because. the indicated hardness of 30 GPa for chromium tetraboride is significantly lower than the theoretical limit values, as well as practically obtained hardness values for the claimed materials.

The hard material known from the indicated source can be used for the manufacture of cutters for drill bits, however, the above disadvantages of the known material do not allow simultaneously high bending and compressive strength, high wear resistance of the product made from the known material.

From the same source, a method for obtaining a material based on chromium tetraboride is known, which includes pressing the initial mixture with heating, which contains boron powder and chromium powder in a ratio of 1: 4.5, after which the pressed sample is placed in a high pressure chamber and synthesis is carried out at 14 GPa and 1200 °C for 45 minutes. Common features of the claimed and known methods are the use of boron powder in the composition of the initial mixture, pre-compression of the initial mixture and the synthesis at high pressures and temperatures. However, the use of chromium powder in the composition of the initial mixture and the absence of an activating and binding agent hinders the formation of chromium tetraboride, and therefore it is necessary to use pressures above 10 GPa. With such high thermobaric parameters, it is possible to obtain only expensive laboratory samples with dimensions of a few millimeters without the possibility of scaling up to industrial production volumes, which, accordingly, complicates the practical applicability of the known method.

Technical task

The technical result of the invention is to provide high wear resistance, heat resistance, hardness and at the same time high flexural and compressive strength. As well as obtaining a material that can be used in practice in a tool, with high wear resistance, heat resistance and hardness, as well as elastic moduli, which provide both high bending and compressive strength. High flexural and compressive strength is ensured at optimal values of the elastic moduli. Optimal in the framework of the claimed invention are high values of Young's modulus, at which the ratio of the shear modulus to the compression modulus is 0.9 or more. With this combination of characteristics, the material has high hardness and low brittleness, which leads to high wear resistance of the material and, accordingly, to high efficiency in operations performed using products and tools made from this material, in particular when using cutting or drilling tools.

The solution of the problem

The technical result is achieved for a hard alloy material based on chromium tetraboride, the phase composition of which includes chromium tetraboride, chromium diboride and a binder, while the content of these components is
_CrB4 45% - 60%
CrB ₂ 25% - 45%
binder 10% - 15%,
where the binder is a metal boride or a mixture of metal borides selected from the group of cobalt, copper, nickel, aluminum.

The technical result is achieved due to the content of components in the phase composition of the hard alloy material, which simultaneously provides high hardness, which is characteristic of chromium tetraboride, high heat resistance, which is characteristic of the chromium boride group, and high values of elastic moduli, at which the ratio of the shear modulus to the compression modulus is greater 0.9.

With a decrease in the content of chromium tetraboride, the hardness of the carbide material itself will decrease. With an increase in the content of chromium tetraboride, a decrease in the ratio of the shear modulus to the compression modulus is observed, which ultimately will not allow to achieve the technical result. The introduction of a binder into the composition of the initial mixture to obtain the claimed material activates the formation and increases the content of chromium tetraboride in the phase composition. An increase in the content of the binder (binder in the initial mixture) in the phase composition will lead to a decrease in hardness and heat resistance and affect the value of the elastic moduli of the material. Reducing the content of the binder (the content of the binder in the initial mixture) will lead to a decrease in the formation and content in the phase composition of the hard alloy material of chromium tetraboride. The binder is a metal boride or a mixture of metal borides, which have a lower melting point and are used as a binder in carbide materials.

The technical result is also achieved for a composite material based on chromium tetraboride, the phase composition of which includes chromium tetraboride, chromium diboride, diamond and a binder, while the content of these components is:
_CrB4 40% - 55%
_CrB2 13% - 40%
diamond 10% - 25%
binder 10% - 15%,
where the binder is a metal boride or a mixture of metal borides selected from the group of cobalt, copper, nickel, aluminum.

The introduction of diamond makes it possible to significantly increase the wear resistance of the composite material. In this case, the thermal stability and elastic moduli change insignificantly. An increase in the diamond content of more than 30% leads to a decrease in the ratio of the shear modulus to the compression modulus and does not make it possible to obtain a material with the desired characteristics, and diamonds are poorly retained in the composite matrix. Reducing the content of diamonds in the composition below 10% does not increase the wear resistance of the composite material and only affects the content of chromium tetraboride in the composite.

Cobalt, copper, nickel, aluminum, due to their properties, in particular the melting point, are used as a binder, which melts during the production of the material, occupies the space between the particles of chromium and boron, while ensuring heat transfer and mass transfer through the melt.

To achieve the technical result, the content of impurities in the materials up to 1%.

Products of various shapes are obtained from the claimed materials, or the materials can be applied as a layer on the surface of any product.

Cobalt boride or a mixture of cobalt borides of composition Co _x B, where x is a number from 1 to 3, can act as a binder. Upon receipt of the claimed material, a mixture of cobalt borides is formed, which may include one or more cobalt borides: CoB, Co ₂ B Co ₃ B. The ratio between different cobalt borides does not significantly affect the properties of the hardmetal material, provided that the total content of cobalt borides in the composition of the material as a binder is from 10% to 15%.

The composition of the binder may additionally include a metal boride selected from the group: titanium, hafnium, niobium or other metals with similar properties. This makes it possible to reduce the amount of metal boride with a lower melting point and ensure the binding of free boron in the composition of the material.

The claimed materials may additionally include a diamond layer. When forming the diamond layer, synthetic diamond micropowders with particle sizes from 3 to 20 microns are used.

The claimed materials may additionally also include a layer made of hard material based on tungsten carbide, in particular the phase composition of which may include 92% tungsten carbide and 8% cobalt. The content of tungsten carbide can vary from 90% to 94%, the rest is cobalt. Or from any other known carbide materials.

Carbide or composite material based on chromium tetraboride can be combined with one of two or two layers at the same time - diamond and / or carbide.

The technical result is achieved by implementing a method for producing hard alloy material, which includes the stages of preparing the initial mixture, which includes powders of chromium diboride (60 - 75 wt.%), boron (15% - 28%) and a binder (8% - 12%), pressing the initial mixture at a pressure of 30 MPa to 50 MPa in a vacuum at a temperature of 1200°C to 1400°C from 30 to 60 minutes, sintering the pressed material in a high pressure chamber at a temperature of 1100°C to 1600°C and a pressure of 1, 0 to 7.0 GPa for 1 to 10 minutes.

The technical result is achieved due to the composition of the initial mixture, the ratio of the components of which ensures the production of a material with a phase composition, under which the technical result is achieved, as well as the conditions of pressing and synthesis (sintering), which ensure the formation of 45% to 60% chromium tetraboride from chromium diboride by mass transfer of boron through the binder melt.

The binder provides, under these conditions, the binding of free boron and the formation of metal borides as a result, which also act as a binder for the chromium tetraboride particles formed during the synthesis and unreacted chromium diboride particles.

The technical result is also achieved when implementing a method for producing a composite material, which includes the stages of preparing the initial mixture, which includes powders of chromium diboride (45 - 65 wt.%), boron (15% - 20%), binder (10% - 12%), diamond (8% - 25%), pressing the initial mixture at a pressure of 30 MPa to 50 MPa in vacuum at a temperature of 1000 ° C to 1200 ° C for 5 to 10 minutes, sintering the pressed material in a high pressure chamber at a temperature of 1100 ° C C to 1500 °C and pressure from 1.0 to 7.0 GPa for 1 to 10 minutes.

The technical result is achieved due to the content of the initial components in the mixture and the synthesis conditions under which the formation of chromium tetraboride with a content of 40% to 55% occurs, and also under which graphitization of diamonds does not occur.

Pressing conditions in the ranges of the claimed methods provide the necessary packing density of the powders, at which, during further sintering, the formation of chromium tetraboride is ensured. Sintering conditions in the stated ranges provide the formation of chromium tetraboride from chromium diboride in materials, as well as sintering of diamonds with other components in a composite material based on chromium tetraboride. Increasing the pressure during sintering is impractical, because does not have a significant positive effect on the properties of the obtained materials, however, it complicates the practical applicability of the method, and an increase in temperature can lead to graphitization of diamonds in the composite material.

Reducing the temperature and pressure will not ensure the formation of chromium tetraboride in the required amount, which will not allow to achieve the technical result.

Upon receipt, the claimed materials may have any shape depending on, for example, the shape of the compact obtained by pressing.

The binder can be cobalt powder, which, when obtaining materials, also acts as a binder between particles of other components, and at the same time provides binding of free boron with the formation of cobalt borides. Additionally, the binder may include a powder of a metal selected from the group of hafnium, niobium, titanium and other metals with similar properties, which will ensure the binding of free boron in the composition of materials.

In processes for producing a carbide or composite material, the chromium diboride powder may have a particle size of 1 to 10 microns. Larger particle sizes lead to a slower transition of chromium diboride to chromium tetraboride. With a smaller particle size, the powders contain more impurities, which can cause technological difficulties in obtaining a hard alloy or composite material based on chromium tetraboride.

In processes for producing hard alloy or composite material, boron powder may have a particle size of less than 3 μm and contain 99.0% or more boron, cobalt powder may have a particle size of 0.2 μm to 2.0 μm and contain 99.5% cobalt or more. With such a particle size and purity of the initial powders, the interaction of the components and the production of materials with the stated phase composition are better.

In the method for producing a composite material based on chromium tetraboride, the diamond powder may have particle sizes from 10 µm to 60 µm. With a smaller size of diamond particles, they do not provide an increase in the wear resistance of the material, with a larger particle size, they are poorly retained in the composite matrix.

The particle shape factor of the diamond powder can be from 1.2 to 1.3.

An additional diamond layer can be added to the pressed material and then sintering is carried out. The diamond layer can be made of diamond micropowder with a particle size of 3 µm to 20 µm.

To the pressed material, a substrate of tungsten carbide-based carbide material can be additionally added, in particular, the phase composition of such material can correspond to 92% tungsten carbide and 8% cobalt.

Also, a layer of carbide material can be added to the pressed material, on one side of which a diamond layer is added, and then sintering is carried out.

The technical result is achieved for a plate made of a hard alloy material based on chromium tetraboride, the phase composition of which includes chromium tetraboride, chromium diboride and a binder, while the content of these components is:
_CrB4 45% - 60%
CrB ₂ 25% - 45%
binder 10% - 15%,
where the binder is a metal boride or a mixture of metal borides selected from the group of cobalt, copper, nickel, aluminum.

And also for a plate made of a composite material based on chromium tetraboride, the phase composition of which includes chromium tetraboride, chromium diboride, diamond and a binder, while the content of these components is:
_CrB4 40% - 55%
_CrB2 13% - 40%
diamond 10% - 25%
binder 10% - 15%,
where the binder is a metal boride or a mixture of metal borides selected from the group of cobalt, copper, nickel, aluminum.

The binder may be a boride or a mixture of cobalt borides of the composition Co _x B, where x is a number from 1 to 3. The binder may additionally include borides of a metal selected from the group titanium, niobium, hafnium, zirconium. The thickness of the claimed plates can range from 3 mm to 10 mm.

Claimed plates may additionally contain a diamond layer, the thickness of which can be from 0.5 mm to 3 mm. In this case, the diamond layer can be made of diamond micropowder with a particle size of 3 µm to 20 µm.

Claimed plates additionally may also contain a layer made of carbide material based on tungsten carbide. Such a layer may also contain the claimed plates, which additionally contain a diamond layer. The phase composition of this layer may include 92% tungsten carbide and 8% cobalt. The thickness of such a layer can be from 2 mm to 5 mm.

The technical result is also achieved for cutting and drilling tools, which include a body and at least one claimed plate.

The technical result is achieved due to the fact that the tools contain elements made of the claimed materials.

The technical result is achieved for a method of drilling underground rocks, in which drilling is carried out with a drilling tool that includes a body and at least one claimed plate. The achievement of the technical result is achieved through the use of a drilling tool, which includes at least one plate made of the claimed carbide or composite material based on chromium tetraboride, which provide high wear resistance, hardness, heat resistance and elastic moduli, which simultaneously provide high bending strength. and compression. This ensures high efficiency of the proposed method.

The following examples of implementation serve to illustrate the invention, but should not be construed as limiting the invention.

Figure.1

[Fig.1] X-ray diffraction pattern of two samples of carbide material based on chromium tetraboride, where 1 is a sample obtained by pressing a mixture that consists of 70% chromium diboride, 20% boron and 10% cobalt, at a pressure of 50 MPa in a vacuum at a temperature of 1400 ° C 30 minutes and sintering at a pressure of 1.5 GPa and a temperature of 1200 °C for 10 minutes, 2 - a sample obtained by pressing a mixture that consists of 75% chromium diboride, 15% boron and 10% cobalt, at a pressure of 30 MPa at a temperature of 1200 °C for 40 minutes and sintering at a pressure of 5.0 GPa and a temperature of 1400 °C for 5 minutes.

Figure.2

[Figure 2] a graph of the relative change in the mass of the samples when they are heated in air to 1000 ° C: 3 - carbide material based on chromium tetraboride, 4 - carbide material based on tungsten carbide.

Figure.3

[Fig. 3] An image obtained by scanning electron microscopy, which shows the microstructure of a carbide material based on chromium tetraboride after heating in air to 1000 ° C, where 5 is a layer of a protective film formed as a result of thermal exposure.

Example 1. An initial mixture is prepared containing 70% by weight of chromium diboride powder (particle size, TU 6-09-03-385-76, total boron-29.5%, free boron-0.5%, total carbon-0 .3%, the amount of the main substance is 99.1%), 20% by weight of boron powder (amorphous boron TU 2112-001-49534204-2003, black color, particle size less than 3 microns, content of the main element 99.2%, main impurities : magnesium, iron, silicon, oxygen content up to 0.5%) and 10% cobalt powder (DIACOB1500, average particle size 1.0-1.5μm, main element content ≥99.5%, impurities: nickel and oxygen). The prepared mixture is placed in a graphite mold and pressed in an evacuated chamber at a pressure of 50 MPa and a temperature of 1400 °C for 30 minutes. As a result, a tablet-compressed sample is obtained, which is subjected to sintering in a high-pressure chamber at a pressure of 1.5 GPa and a temperature of 1200°C for 10 minutes. As a result, a sample with a diameter of 11 mm and a thickness of 5 mm was obtained with a phase composition of CrB ₄ - 50%, CrB ₂ - 38%, Co _x B - 12%.

Example 2. An initial mixture is prepared containing 75% by weight of chromium diboride powder (particle size, TU 6-09-03-385-76, total boron-29.5%, free boron-0.5%, total carbon-0 .3%, the amount of the main substance is 99.1%), 15% by weight of boron powder (amorphous boron TU 2112-001-49534204-2003, black color, particle size less than 3 microns, content of the main element 99.2%, main impurities : magnesium, iron, silicon, oxygen content up to 0.5%) and 10% cobalt powder (DIACOB1500, average particle size 1.0-1.5μm, main element content ≥99.5%, impurities: nickel and oxygen). The prepared mixture is placed in a graphite mold and subjected to pressing in an evacuated chamber at a pressure of 30 MPa and a temperature of 1200 °C for 40 minutes. As a result, a tablet-compressed sample is obtained, which is subjected to sintering in a high-pressure chamber at a pressure of 5.0 GPa and a temperature of 1400° C. for 5 minutes. As a result, a sample with a diameter of 11 mm and a thickness of 5 mm was obtained with a phase composition of CrB ₄ - 55%, CrB ₂ - 33%, Co _x B - 12%.

The figure 1 shows the diffraction patterns for samples from examples 1 and 2, and also given the reference diffractograms of tetraboride and chromium diboride. Dots mark peaks belonging to cobalt borides. The phase composition of the obtained samples was determined using X-ray phase analysis (the error of the method can be from 1 to 2%).

Similar to examples 1 and 2, at various temperatures and pressures, a number of samples were obtained from hard alloy and composite material based on chromium tetraboride.

To confirm the achievement of the technical result, we studied the properties of the obtained materials based on chromium tetraboride, as well as commercially available hard-alloy material based on tungsten carbide (VK8, phase composition: 92% tungsten carbide WC and 8% cobalt).

The results of the study of the hardness of the samples confirm the achievement of the technical result in terms of obtaining materials based on chromium tetraboride with high hardness.

The hardness of the obtained materials was estimated from the diameter of the indentation from the indentation of a diamond cone into the polished surface of composites based on chromium borides at a load of 600 N. For all samples of hard alloy material based on chromium tetraboride, the hardness was from 32 to 36 GPa. For samples of a composite material based on chromium tetraboride with diamond powder, the hardness ranged from 35 to 41 GPa. The hardness of samples of hard alloy material based on tungsten carbide was 27 GPa. Table 1 shows examples of hardness values for several samples.

Wear resistance tests were carried out on a green silicon carbide abrasive wheel (1A1 350x40x127 63C). Wear resistance was evaluated by the wear area of the composites after 30 passes. The phase composition and test results for several samples are also shown in Table 1. In terms of the conditions for obtaining samples, the composition of the initial mixture in wt.% is indicated with powder characteristics similar to those indicated in examples 1 and 2. The pressing processes were carried out in the same way as indicated in examples 1 and 2.

The composition of the initial mixture,% by weight	Sintering conditions	Phase composition of the composite	Wear scar area on the abrasive wheel, mm 2	Hardness, GPa
Carbide crumb with composition 92WC-8Co	7.0 GPa, 1400 °С, 2 minutes.	WC - 92%, Co - 8%	4.30	27
60% CrB2, 28% B, 12% Co	5.0 GPa, 1300 °С, 3 min.	CrB4 - 45% CrB 2 - 43% Co x B - 12%	3.90	32
66% CrB2 , 24% B, 10% Co	5.0 GPa, 1400 °С, 2 minutes.	CrB 4 - 55% CrB 2 - 30% Co x B - 15%	3.55	35
70% CrB2 , 22% B, 8% Co	7.0 GPa, 1500 °С, 2 minutes.	CrB 4 - 58% CrB 2 - 30% Co x B - 12%	3.40	36
65% CrB 2 , 15% B, 10% Co, 10% C (C - diamond 28/20 microns).	5.0 GPa, 1500 °С, 3 min.	CrB4 - 40% CrB 2 - 38% Co x B - 12% diamond - 10%	2.75	38
60% CrB2 , 18% B, 12% Co, 10% C (C - diamond 28/20 microns).	7.0 GPa, 1600 °С, 5 minutes.	CrB4 - 55% CrB 2 - 20% Co x B - 15% diamond - 10%	2.40	41
60% CrB 2 , 20% B, 10% Co, 10% C (C - diamond 28/20 microns).	7.0 GPa, 1600 °С, 3 min.	CrB 4 - 50% CrB 2 - 28% Co x B - 12% diamond - 10%	2.55	40

As can be seen from Table 1, the wear area for a sample of a hard-alloy material based on tungsten carbide is larger compared to samples of a hard-alloy material based on chromium tetraboride and is significantly larger compared to samples of a composite material based on chromium tetraboride, which confirms the achievement of the technical result in terms of high wear resistance.

The elastic moduli of the materials were calculated from the velocity of ultrasound passing through samples 11 mm in diameter and 5 mm high. The results are presented in Table 2. The mixtures were pressed in an evacuated chamber at a pressure of 30 MPa and a temperature of 1200°C for 30 minutes.

The composition of the initial mixture,% by weight	Sintering modes	Phase composition of the composite	G, GPa	B, GPa	E, GPa	G/B ratio
92WC-8Co, carbide chips	7.0 GPa, 1400 °С, 2 minutes.	WC - 92%, Co -8%	186	222	445	0.84
73% CrB 2 , 15% B, 12% Co	7.0 GPa, 1300 °С, 2 minutes.	CrB 4 - 45% CrB 2 - 40% Co x B - 15%	193	184	389	1.05
66% CrB 2 , 22% B, 12% Co	7.0 GPa, 1400 °С, 2 minutes.	CrB 4 - 50% CrB 2 - 35% Co x B - 15%	224	206	443	1.09
66% CrB 2 , 22% B, 12% Co	7.0 GPa, 1500°C, 3 min.	CrB 4 - 60% CrB 2 - 25% Co x B - 15%	235	254	493	0.93
65% CrB 2 , 15% B, 10% Co, 10% diamond	7.0 GPa, 1350 °С, 2 minutes.	CrB 4 - 45% CrB 2 - 33% Co x B - 12% diamond -10%	198	215	425	0.92
60% CrB 2 , 20% B, 12% Co, 8% diamond	7.0 GPa, 1450 °С, 2 minutes.	CrB 4 - 55% CrB 2 - 20% Co x B - 15% diamond -10%	242	267	477	0.91
45% CrB 2 , 20% B, 10% Co, 25% diamond	1.5 GPa, 1100 °C, 10 min.	CrB 4 - 45% CrB 2 - 18% Co x B - 12% diamond -25%	182	194	370	0.94
45% CrB 2 , 20% B, 10% Co, 25% diamond	1.5 GPa, 1200 °C, 10 min.	CrB 4 - 50% CrB 2 - 13% Co x B - 12% diamond -25%	192	189	392	1.02

G - shear modulus
B - compression modulus
E is Young's modulus.

Table 2 shows that despite the high values of the Young's modulus, the ratio of the shear modulus to the compression modulus for a sample of carbide material based on tungsten carbide is less than 0.9. For specimens made of hard alloy and composite material based on chromium tetraboride, rather high values of Young's modulus were also obtained, but at the same time, they are characterized by a ratio of shear modulus to compression modulus of 0.9 or more. The obtained results also confirm the achievement of the technical result.

The temperature stability of the obtained samples was evaluated by the results of thermogravimetric analysis. Samples of the claimed material and hard alloy based on tungsten carbide (VK8) weighing about 20 mg were heated in air to 1000°C at a rate of 10°C/min. As can be seen from figure 2, the hard-alloy material based on chromium tetraboride practically does not change its weight in the temperature range of 400-1000 °C. At the same time, the hard alloy breaks down and oxidizes during heating. The oxidation process is active at temperatures above 800°C and is accompanied by a significant increase in the weight of the samples. Materials based on chromium borides are not destroyed due to the formation of a vitreous protective film on their surface ( ). Composite materials based on chromium tetraboride are also characterized by high heat resistance due to the formation of a vitreous film on the surface, which has a protective effect on diamonds, which are part of the composite material, and prevents their destruction and graphitization.

Thus, the examples given and the results of studying the properties of the obtained samples from hard alloy and composite materials based on chromium tetraboride confirm the achievement of the technical result: obtaining a material with high hardness, wear resistance, heat resistance and at the same time high bending and compressive strength.

Patent Literature

1. US 20140262542 "Downhole tools including ternary boride-based cermet and methods of making the same", publ. 09/18/2014, IPC: E21B 10/567, B24D 8/00.

2. US6007922 "Chromium boride coatings", publ. 12/28/1999, IPC: B22F 7/04, B05D 5/00.

Claims (65)

1. Carbide material based on chromium tetraboride, the phase composition of which includes chromium tetraboride, chromium diboride and a binder, while the content of these components is:
   _CrB4 45% - 60%
   CrB ₂ 25% - 45%
   binder 10% - 15%,
   where the binder is a metal boride or a mixture of metal borides selected from the group of cobalt, copper, nickel, aluminum.
2. The carbide material based on chromium tetraboride according to claim 1, in which the binder is a cobalt boride or a mixture of cobalt borides of the composition Co _x B, where x is a number from 1 to 3.
3. A carbide material based on chromium tetraboride according to claim 1, in which the binder additionally contains a metal boride selected from the group of titanium, niobium, hafnium, zirconium.
4. The carbide material based on chromium tetraboride according to claim 1, which additionally contains a diamond layer.
5. The carbide material based on chromium tetraboride according to claim 4, in which the diamond layer is made of diamond micropowder with a particle size of 3 µm to 20 µm.
6. The carbide material based on chromium tetraboride according to claim 1 or claim 4, which further comprises a layer made of hard metal based on tungsten carbide.
7. The chromium tetraboride carbide material according to claim 6, wherein the phase composition of the tungsten carbide carbide material comprises 92% tungsten carbide and 8% cobalt.
8. A composite material based on chromium tetraboride, the phase composition of which includes chromium tetraboride, chromium diboride, diamond and a binder, the content of these components being:
   _CrB4 40% - 55%
   _CrB2 13% - 40%
   diamond 10% - 25%
   binder 10% - 15%,
   where the binder is a metal boride or a mixture of metal borides selected from the group of cobalt, copper, nickel, aluminum.
9. The chromium tetraboride composite material according to claim 8, wherein the binder is cobalt boride or a mixture of cobalt borides of composition Co _x B, where x is a number from 1 to 3.
10. Composite material based on chromium tetraboride according to claim 8, in which the binder additionally contains a metal boride selected from the group of titanium, niobium, hafnium, zirconium.
11. Composite material based on chromium tetraboride according to claim 8, which additionally contains a diamond layer.
12. Composite material based on chromium tetraboride according to claim 11, in which the diamond layer is made of diamond micropowder with a particle size of 3 µm to 20 µm.
13. The chromium tetraboride composite material according to claim 8 or claim 11, which further comprises a layer made of tungsten carbide hardmetal material.
14. The chromium tetraboride composite material of claim 13, wherein the phase composition of the tungsten carbide carbide material comprises 92% tungsten carbide and 8% cobalt.
15. A method for producing a hard alloy material based on chromium tetraboride, comprising the steps:
    - preparation of the initial mixture, which includes powders
    chromium diboride 60% - 75%
    boron 15% - 28%
    binder 8% - 12%,
    where the binder is a powder of a metal selected from the group of cobalt, copper, nickel, aluminum;
    - pressing the initial mixture at a pressure of 30 MPa to 50 MPa in vacuum at a temperature of 1200 °C to 1400 °C for 30 to 60 minutes;
    - sintering of the pressed material in a high pressure chamber at a temperature of 1100 °C to 1600 °C and a pressure of 1.0 to 7.0 GPa for 1 to 10 minutes.
16. The method for producing a carbide material based on chromium tetraboride according to claim 15, in which the binder is a cobalt powder.
17. The method for producing a hard alloy material based on chromium tetraboride according to claim 15, in which the binder additionally includes a powder of a metal selected from the group of titanium, niobium, hafnium, zirconium.
18. A method for producing a hard alloy material based on chromium tetraboride according to claim 15, wherein the chromium diboride powder has a particle size of 1 to 10 µm.
19. The method for producing a chromium tetraboride hard alloy material according to claim 15, wherein the boron powder has a particle size of less than 3 µm and contains 99.0% or more of boron.
20. The method for producing a hard alloy material based on chromium tetraboride according to claim 16, wherein the cobalt powder has a particle size of 0.2 µm to 2.0 µm and contains 99.5% or more cobalt.
21. The method for producing a hard alloy material based on chromium tetraboride according to claim 15, wherein a diamond layer is further added to the compacted material and then sintering is carried out.
22. The method for producing a hard alloy material based on chromium tetraboride according to claim 21, in which the diamond layer is made of diamond micropowder with a particle size of 10 µm to 60 µm.
23. The method for producing a chromium tetraboride hardmetal material according to claim 15 or claim 21, wherein a layer of tungsten carbide based hardmetal material is further added to the compacted material and then sintering is performed.
24. The method for producing a hardmetal material based on chromium tetraboride according to claim 23, wherein the layer of hardmetal material based on tungsten carbide consists of 92% tungsten carbide and 8% cobalt.
25. A method for producing a composite material based on chromium tetraboride, including the steps:
    - preparation of the initial mixture, which includes powders
    chromium diboride 45% - 65%
    boron 15% - 20%
    diamond 8% - 25%
    binder 10% - 12%,
    where the binder is a powder of a metal selected from the group of cobalt, copper, nickel, aluminum;
    - pressing the initial mixture at a pressure of 30 MPa to 50 MPa in a vacuum at a temperature of 1000°C to 1200°C for 5 to 10 minutes;
    - sintering of the pressed material in a high-pressure chamber at a temperature of 1100 °C to 1500 °C and a pressure of 1.0 to 7.0 GPa for 1 to 10 minutes.
26. The method for producing a composite material based on chromium tetraboride according to claim 25, in which the binder is a cobalt powder.
27. The method for producing a hard alloy material based on chromium tetraboride according to claim 25, in which the binder additionally includes a powder of a metal selected from the group of titanium, niobium, hafnium, zirconium.
28. A method for producing a composite material based on chromium tetraboride according to claim 25, wherein the chromium diboride powder has a particle size of 1 to 10 µm.
29. The method for producing a chromium tetraboride composite material according to claim 25, wherein the boron powder has a particle size of less than 3 µm and contains 99.0% or more of boron.
30. A method for producing a composite material based on chromium tetraboride according to claim 25, wherein the diamond powder has a particle size of 10 µm to 60 µm.
31. The method for producing a composite material based on chromium tetraboride according to claim 30, wherein the particle shape factor of the diamond powder is from 1.2 to 1.3.
32. The method for producing a chromium tetraboride composite material according to claim 26, wherein the cobalt powder has a particle size of 0.2 µm to 2.0 µm and contains 99.5% or more cobalt.
33. The method for producing a composite material based on chromium tetraboride according to claim 25, wherein a diamond layer is additionally added to the pressed material and then sintering is carried out.
34. A method for producing a composite material based on chromium tetraboride according to claim 33, in which the diamond layer is made of diamond micropowder with a particle size of 3 µm to 20 µm.
35. The method for producing a chromium tetraboride composite material according to claim 25 or claim 33, wherein a layer of tungsten carbide-based carbide material is further added to the compacted material, and then sintering is carried out.
36. The method for producing a chromium tetraboride composite material according to claim 35, wherein the tungsten carbide-based hardmetal material layer consists of 92% tungsten carbide and 8% cobalt.
37. A plate made of a hard alloy material based on chromium tetraboride, the phase composition of which includes chromium tetraboride, chromium diboride and a binder, while the content of these components is:
    _CrB4 45% - 60%
    CrB ₂ 25% - 45%
    binder 10% - 15%,
    where the binder is a metal boride or a mixture of metal borides selected from the group of cobalt, copper, nickel, aluminum.
38. The plate according to claim 37, wherein the binder is cobalt boride or a mixture of cobalt borides of composition Co _x B, where x is a number from 1 to 3.
39. The plate according to claim 37, in which the binder additionally contains a metal boride selected from the group of titanium, niobium, hafnium, zirconium.
40. The plate according to claim 37, which further comprises a diamond layer.
41. The plate according to claim 40, in which the diamond layer is made of diamond micropowder with a particle size of 3 µm to 20 µm.
42. The plate according to claim 40, wherein the thickness of the diamond layer is between 0.5 mm and 3 mm.
43. The insert according to claim 37, which further comprises a layer made of tungsten carbide based carbide material.
44. The insert of claim 43 wherein the phase composition of the tungsten carbide based carbide material comprises 92% tungsten carbide and 8% cobalt.
45. The insert according to claim 43, wherein the thickness of the layer made of tungsten carbide based carbide material is between 2 mm and 5 mm.
46. The insert according to claim 40, which further comprises a layer made of a hard material based on tungsten carbide.
47. The insert of claim 46 wherein the phase composition of the tungsten carbide carbide material comprises 92% tungsten carbide and 8% cobalt.
48. The insert according to claim 46, wherein the thickness of the layer made of tungsten carbide based carbide material is between 2 mm and 5 mm.
49. Plate according to claim 37, the thickness of which is from 3 mm to
    10 mm.
50. A plate made of a composite material based on chromium tetraboride, the phase composition of which includes chromium tetraboride, chromium diboride, diamond and a binder, the content of these components being:
    _CrB4 40% - 55%
    _CrB2 13% - 40%
    diamond 10% - 25%
    binder 10% - 15%,
    where the binder is a metal boride or a mixture of metal borides selected from the group of cobalt, copper, nickel, aluminum.
51. The plate according to claim 50, wherein the binder is cobalt boride or a mixture of cobalt borides of composition Co _x B, where x is a number from 1 to 3.
52. The plate according to claim 50, in which the binder additionally contains a metal boride selected from the group of titanium, niobium, hafnium, zirconium.
53. The plate according to claim 50, which further comprises a diamond layer.
54. The plate according to claim 53, in which the diamond layer is made of diamond micropowder with a particle size of 3 µm to 20 µm.
55. The plate according to claim 53, wherein the thickness of the diamond layer is between 0.5 mm and 3 mm.
56. The insert according to claim 50, which further comprises a layer made of a hard material based on tungsten carbide.
57. The insert of claim 56 wherein the phase composition of the tungsten carbide carbide material comprises 92% tungsten carbide and 8% cobalt.
58. The insert according to claim 56, wherein the thickness of the layer made of tungsten carbide based carbide material is 2 mm to 5 mm.
59. The insert according to claim 53, which further comprises a layer made of tungsten carbide-based carbide material.
60. An insert as claimed in claim 59, wherein the phase composition of the tungsten carbide carbide material comprises 92% tungsten carbide and 8% cobalt.
61. The insert according to claim 59, wherein the thickness of the layer made of tungsten carbide based carbide material is 2 mm to 5 mm.
62. Plate according to claim 50, the thickness of which is from 3 mm to
    10 mm.
63. A cutting tool, including a body and at least one plate, made according to any one of paragraphs. 37 - 62.
64. Drilling tool, including a body and at least one plate, made according to any one of paragraphs. 37 - 62.
65. A method of drilling underground rocks, in which drilling is carried out with a drilling tool according to clause 64.

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