A tungsten carbide anvil assembly for generating ultra-high pressure

Abstract

The application discloses a tungsten carbide anvil assembly for generating ultrahigh pressure and relates to the technical field of high-temperature and high-pressure of large-cavity presses, which comprises eight cubic blocks of tungsten carbide hard alloy, eight anvils are assembled into a regular cube, trapezoidal gaps are formed between two adjacent anvils, each trapezoidal gap is supported by a supporting block, each anvil is cut into an equilateral triangle section as an anvil surface towards the vertex of the regular cube, each anvil surface encloses an octahedral cavity, three inclined surfaces around each anvil surface are fixedly connected with a piece of pyrophyllite as a high-pressure sealing edge in close proximity to the edge of the anvil surface, an eight-faced pressure-transmitting medium is arranged in the octahedral cavity, a first through hole and a second through hole are arranged on the eight-faced pressure-transmitting medium, three zirconia tubes are sequentially arranged in the first through hole, molybdenum column electrodes are arranged in the zirconia tubes at two ends, a hollow rhenium cylinder is arranged in the middle zirconia tube, and an alumina tube is arranged in the hollow rhenium cylinder. The application can realize an ultrahigh pressure and high-temperature environment on a multi-surface anvil large-cavity press.

Description

Technical Field

[0001] This invention relates to the field of high temperature and high pressure technology for large cavity presses, and in particular to a tungsten carbide anvil assembly for generating ultra-high pressure. Background Technology

[0002] Large-cavity presses are crucial equipment for the mass production of new materials. Superhard materials, such as diamond, synthesized under high temperature and pressure using these presses have been widely applied in key national sectors including machining, oil and gas extraction, geological drilling, and national defense. Expanding the temperature and pressure range achievable by large-cavity presses while maintaining a large high-pressure cavity size is of significant value for achieving large-scale synthesis of new materials under high pressure and for future industrial applications. Related technologies can also be used to simulate the deep Earth environment, contributing to understanding mineral formation mechanisms, the Earth's internal water cycle, and earthquake prediction.

[0003] Breakthroughs in ultra-high pressure and high temperature technology using large-cavity presses can help explore the synthesis and property research of novel functional materials under extreme conditions. However, according to the pressure generation law P=F / S, generating ultra-high pressure over a large force-bearing area is greatly limited. The ultimate pressure of commercially available large-cavity press instruments is usually limited to below 250,000 atmospheres. The biggest challenge lies in how to develop and design high-pressure assemblies based on cemented carbide anvils, including the assembly design of pressure generation and transmission medium materials, heat generation and insulation materials. Internationally, only a few research groups have been able to break through the pressure generation limit of large-cavity presses using tungsten carbide or sintered diamond anvils, achieving pressures exceeding 30 GPa at high temperatures. Breaking through the pressure limit of commercially available large-cavity presses and developing large-cavity presses and related technologies with a wider temperature and pressure range is crucial for the exploration of new materials and the study of the composition of matter inside planets such as Earth. In recent years, research teams from Okayama University in Japan and the University of Bayreuth in Germany have successfully generated ultra-high pressures of 65 GPa at room temperature and 52 GPa at a high temperature of 2000 K using a hard tungsten carbide TJS01 anvil in a DIA-type large-cavity press. However, this type of press and its assembly are characterized by high usage barriers and high load requirements, and the ultimate pressure decreases significantly with increasing temperature. Domestic technological progress in large-cavity presses has long been limited to ultimate pressures below 20 GPa, and the technology for generating ultra-high pressures of general-purpose large-cavity presses above 25 GPa at high temperatures remains extremely challenging. Summary of the Invention

[0004] The purpose of this invention is to provide a tungsten carbide anvil assembly for generating ultra-high pressure, so as to solve the problems existing in the prior art. It can realize ultra-high pressure and high temperature environment in a 6-8 type multi-faceted anvil large cavity press, and achieve the goal of exploring new materials and new properties in the ultra-high temperature and pressure range.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] This invention provides a tungsten carbide anvil assembly for generating ultra-high pressure, comprising eight tungsten carbide cemented carbide cubic anvils assembled into a cube. The opposite faces of two adjacent anvils are inclined outwards from the end closer to the center of the cube towards the end farther from the center, forming a trapezoidal gap between adjacent anvils. The constricted end of the trapezoidal gap faces the center of the cube. Each trapezoidal gap supports two support blocks. An equilateral triangular cross-section is cut from the apex of each anvil towards the center of the cube, serving as the pressure-generating anvil surface. Each anvil surface forms an octahedral cavity. Three inclined surfaces around each anvil surface, adjacent to the edge of the anvil surface, are each fixedly connected to a pyrophyllite sheet as a high-pressure sealing edge for sealing the octahedral cavity. An octahedral cavity contains a pressure-transmitting medium octahedron. Two opposite faces of the octahedron have a through-hole at their center, and two opposite edges have a through-hole at their center. A first zirconia tube, a third zirconia tube, and a second zirconia tube are sequentially arranged axially within the first through-hole. Molybdenum column electrodes are disposed within the first and second zirconia tubes. A hollow rhenium cylinder is disposed within the third zirconia tube. The two molybdenum column electrodes are connected to both ends of the rhenium cylinder. An alumina tube is disposed within the rhenium cylinder, serving as a sample chamber. The two ends of a thermocouple are inserted into the second through-holes on both sides of the rhenium cylinder. The two ends of the thermocouple pass through the third zirconia tube and contact the rhenium cylinder to measure its temperature.

[0007] Preferably, the anvil has an average particle size of 0.37 μm, a standard deviation of particle size distribution of 0.11 μm, a cobalt binder content of 4.0 wt.%, a Roche hardness of 93.5 HRA, a side length of 25.4 mm, an inclination angle of 1° for the three bevels around the anvil, and a side length of 1.5 mm.

[0008] Preferably, the support block is a balsa wood block, which is a cuboid wood block with a bottom side length of 5.0 mm and a height of 2.9 mm; two of the support blocks in each trapezoidal gap are bonded to one of the pressing anvils and are symmetrically arranged about the diagonal of the inclined surface passing through the anvil surface, and each support block is symmetrically arranged about the other diagonal of the inclined surface.

[0009] Preferably, the cross-section of the pyrophyllite sheet is an isosceles trapezoid with a base angle of 45°. The upper base of the isosceles trapezoid is 2.9 mm long, and the upper base is chamfered at 54°44′8.15″ towards the inside of the pyrophyllite sheet. The angle is half of the dihedral angle of the octahedron of the pressure-transmitting medium. The thickness of the pyrophyllite sheet is 1.0 mm ± 0.02 mm, and the width is 3.0 mm. The pyrophyllite sheet is glued around the anvil surface.

[0010] Preferably, an insulating and heat-resistant tape is bonded to the three beveled surfaces around each of the anvils; the four outer surfaces of the pressing anvils that constitute each outer surface of the cube are bonded and fixed by an epoxy resin board, which is a square epoxy resin sheet with a side length of 48mm and a thickness of 0.4mm.

[0011] Preferably, the pressure-transmitting medium octahedron is a chromium oxide-doped magnesium oxide ceramic material with a Vickers hardness of 400 MPa; the first zirconia tube, the second zirconia tube, and the third zirconia tube are made of hard ceramic material with a Vickers hardness of 600 MPa containing calcium oxide as a stabilizer.

[0012] Preferably, the diameter of the first through hole is 2.0 mm, and the diameter of the second through hole is 0.5 mm; the outer diameter of the first zirconia tube and the second zirconia tube is 2.0 mm, and the inner diameter is 1.5 mm; the outer diameter of the third zirconia tube is 2.0 mm, and the inner diameter is 1.5 mm; the third zirconia tube has through holes of 0.3 mm in diameter at the center of both sides of its tube wall for the passage of the two electrodes of the thermocouple; the diameter of the molybdenum column electrode is 0.5 mm; and the rhenium cylinder is a closed cylinder with a bottom diameter of 1.2-1.3 mm and a height of 1.9-2.1 mm.

[0013] Preferably, copper wire with a diameter of 0.1 mm is wound around the thermocouple at the positions corresponding to the octahedron of the pressure-transmitting medium and the pyrophyllite sheet, and the copper wire is without insulating varnish.

[0014] The present invention achieves the following technical effects compared to the prior art:

[0015] The tungsten carbide anvil assembly for generating ultra-high pressure provided by this invention comprises eight cubic anvil blocks made of tungsten carbide hard alloy assembled into a cube. The two opposite faces of each anvil are inclined and supported by a support block. An equilateral triangular cross-section is cut at the apex of each anvil facing the center of the cube, serving as the pressure-generating anvil surface. Each anvil surface forms an octahedral cavity. A pyrophyllite sheet is fixedly connected to the edges of each of the three inclined surfaces around the anvil surface as a high-pressure sealing edge to seal the octahedral cavity. An octahedral pressure-transmitting medium is disposed within the octahedral cavity. A first zirconia tube, a second zirconia tube, and a third zirconia tube are sequentially disposed within the first through-hole of the octahedral pressure-transmitting medium. A pressure-transmitting medium is disposed within the first and second zirconia tubes. A molybdenum column electrode is used, with a hollow rhenium cylinder placed inside a third zirconia tube. Two molybdenum column electrodes are connected to both ends of the rhenium cylinder. An alumina tube is placed inside the hollow rhenium cylinder, and the alumina tube serves as the sample chamber. The two ends of a thermocouple are inserted into the second through holes on both sides of the rhenium cylinder. The two ends of the thermocouple pass through the third zirconia tube and contact the rhenium cylinder to measure its temperature. The assembly is placed in a 6-8 type multi-faceted anvil large-cavity press. The rhenium cylinder is heated by energizing the molybdenum column electrodes to heat the sample chamber and create a high-temperature environment. Eight cubic anvils are then pressed, and the octahedral cavity formed by the anvil faces of the eight cubic anvils is compressed to generate an ultra-high pressure and high temperature environment, achieving the goal of exploring new materials and properties in the ultra-high temperature and pressure range. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A schematic diagram of the tungsten carbide anvil assembly for generating ultra-high pressure provided by the present invention;

[0018] Figure 2 A schematic diagram of the assembly method of the octahedron of the internal pressure transmission medium and the sample chamber of the tungsten carbide anvil assembly for generating ultra-high pressure provided by the present invention.

[0019] Figure 3 This is a graph showing the change in the resistivity of zirconium under high pressure as a function of the applied load, as measured in Example 1 of the present invention.

[0020] Figure 4 This is a comparison of the curves showing the actual pressure changes with oil pressure in the octahedral cavity at room temperature and high temperature in Embodiment 1 and Comparative Example 1 of the present invention.

[0021] Figure 5The images show backscattered electron images and electron probe microanalysis results of the alumina-containing brigmanite minerals synthesized at high temperature in Example 2 of this invention.

[0022] In the figure: 1-anvil, 2-trapezoidal gap, 3-support block, 4-pyrophyllite sheet, 5-pressure transmission medium octahedron, 6-first zirconia tube, 7-second zirconia tube, 8-third zirconia tube, 9-molybdenum column electrode, 10-rhenium cylinder, 11-alumina tube, 12-sample chamber, 13-thermocouple, 14-epoxy resin board, 15-copper wire. Detailed Implementation

[0023] like Figures 1-5 As shown, this invention provides a tungsten carbide anvil assembly for generating ultra-high pressure, comprising eight tungsten carbide hard alloy cubic anvils 1, which are assembled into a cube. The opposite faces of two adjacent anvils 1 are inclined outwards from the end closest to the center of the cube to the end furthest from the center, forming a trapezoidal gap 2 between adjacent anvils 1. The constricted end of the trapezoidal gap 2 faces the center of the cube. Each trapezoidal gap 2 supports two support blocks 3. An equilateral triangular cross-section is cut at the apex of each anvil 1 facing the center of the cube as the pressure-generating anvil surface. Each anvil surface forms an octahedral cavity. A pyrophyllite sheet 4 is fixedly connected to each of the three inclined surfaces around each anvil surface adjacent to the edge of the anvil surface as a high-pressure sealing edge to seal the octahedral cavity. An octahedron 5 is provided as a pressure-transmitting medium. A first through hole is provided at the center of two opposite faces of the octahedron 5, and a second through hole is provided at the center of two opposite edges. A first zirconia tube 6, a third zirconia tube 8, and a second zirconia tube 7 are arranged sequentially along the axial direction in the first through hole. Molybdenum column electrodes 9 are arranged in the first zirconia tube 6 and the second zirconia tube 7. A hollow rhenium cylinder 10 is arranged in the third zirconia tube 8. The two molybdenum column electrodes 9 are respectively connected to the two ends of the rhenium cylinder 10. An alumina tube 11 is arranged in the rhenium cylinder 10. The alumina tube 11 is a sample chamber 12 for holding the sample. The two poles of a thermocouple 13 are respectively inserted into the second through holes on both sides of the rhenium cylinder 10. The two poles of the thermocouple 13 pass through the third zirconia tube 8 and contact the rhenium cylinder 10 for measuring the temperature of the rhenium cylinder 10.

[0024] As an embodiment of the present invention, the anvil 1 has an average particle size of 0.37 μm, a standard deviation of particle size distribution of 0.11 μm, a cobalt binder content of 4.0 wt.%, and a Roche hardness of 93.5 HRA.

[0025] As an embodiment of the present invention, the side length of the anvil 1 is 25.4 mm.

[0026] As an embodiment of the present invention, the inclination angle of the three inclined surfaces around the anvil surface of the pressing anvil 1 is 1°, and the side length of the anvil surface is 1.5mm.

[0027] As an embodiment of the present invention, the support block 3 is a balsa wood block. The balsa wood block is preferably a cuboid wood block with a bottom side length of 5.0 mm and a height of 2.9 mm, which serves to support the pressing anvil 1 and stabilize the position of the pressing anvil 1.

[0028] In one embodiment of the present invention, the pyrophyllite sheet 4 has an isosceles trapezoid with a base angle of 45°. The upper base of the isosceles trapezoid is 2.9 mm long, and the upper base is chamfered at 54°44′8.15″ towards the inside of the pyrophyllite sheet 4. The angle is half of the dihedral angle of the pressure-transmitting medium octahedron 5. The thickness of the pyrophyllite sheet 4 is 1.0 mm ± 0.02 mm, and the width is 3.0 mm. The pyrophyllite sheet 4 is glued to the anvil surface. The pyrophyllite sheet 4 is glued so that the bottom edge of the bottom surface aligns with the edge of the anvil 1, and the left side of the trapezoid aligns with the edge of the anvil 1. One pyrophyllite sheet 4 is glued to each of the three sides around the anvil surface of each anvil 1. A total of 24 pyrophyllite sheets 4 are required for eight anvils 1, which can form a good seal for the internal octahedral cavity under high pressure.

[0029] As an embodiment of the present invention, two basalt blocks should be pasted on the outer part of the long base of the pyrophyllite sheet 4. Preferably, the two support blocks 3 in each trapezoidal gap 2 are bonded to one of the pressing anvils 1 and are symmetrically arranged about the diagonal of the inclined surface passing through the anvil surface. Each support block 3 is symmetrically arranged about the other diagonal of the inclined surface.

[0030] As an embodiment of the present invention, a layer of insulating heat-resistant tape is bonded to the three beveled surfaces around each anvil; the insulating heat-resistant tape is preferably 0.08mm*19mm*10mm in size.

[0031] In one embodiment of the present invention, the outer surfaces of the four anvils 1 constituting each outer surface of the cube are bonded and fixed by epoxy resin boards 14. The epoxy resin boards 14 are preferably square epoxy resin sheets with a side length of 48 mm and a thickness of 0.4 mm, and are fixed to the anvils 1 by double-sided adhesive. The epoxy resin boards 14 are attached to the outside of the anvils 1 to provide insulation, reduce the external stress of the anvils 1 when under pressure, and fix the initial position of the anvils 1.

[0032] In one embodiment of the present invention, the pressure-transmitting medium octahedron 5 is a chromium oxide-doped magnesium oxide ceramic material with a Vickers hardness of 400 MPa. It is filled with hard ceramic and metallic materials to achieve the functions of generating ultra-high pressure by extruding the internal material in the anvil 1 and generating high temperature by applying electricity. The pressure-transmitting medium octahedron 5 is a regular octahedron with a side length of 6.0 mm. A first through hole with a diameter of 2.0 mm is machined from the center of one face of the pressure-transmitting medium octahedron 5 towards the center of the opposite side face. A second through hole with a diameter of 0.5 mm is machined from the center of one edge of the pressure-transmitting medium octahedron 5 towards the center of the opposite edge face, with the second through hole passing through the center of the through hole in the center of the face face. After drilling, the pressure-transmitting medium octahedron 5 is cleaned with acetone and then subjected to high-temperature resintering at 1000°C to remove impurities.

[0033] As an embodiment of the present invention, the first zirconia tube 6, the second zirconia tube 7 and the third zirconia tube 8 are made of hard ceramic material with a Vickers hardness of 600 MPa containing calcium oxide as a stabilizer.

[0034] In one embodiment of the present invention, the diameter of the first through hole is 2.0 mm, and the diameter of the second through hole is 0.5 mm; the outer diameter of the first zirconia tube 6 and the second zirconia tube 7 are 2.0 mm, the inner diameter is 1.5 mm, and the height is about 1.35 mm, which are used to provide heat insulation on the upper and lower sides of the rhenium cylinder 10 and to fix the molybdenum column inside the tube as the electrode material; the outer diameter of the third zirconia tube 8 is 2.0 mm, the inner diameter is 1.5 mm, and the center of both sides of the tube wall of the third zirconia tube 8 is provided with a through hole with a diameter of 0.3 mm, which are used for the two poles of the thermocouple 13 to pass through respectively; the third zirconia tube 8 serves to provide heat insulation on the tube wall of the rhenium cylinder 10; the diameter of the molybdenum column electrode 9 is 0.5 mm; the height of the molybdenum column electrode 9 should be basically consistent with that of the first zirconia tube 6 and the second zirconia tube 7, which is about 1.35 mm.

[0035] In one embodiment of the present invention, the rhenium cylinder 10 is a closed cylinder with a bottom diameter of 1.2-1.3 mm and a height of 1.9-2.1 mm. When energized, the rhenium cylinder 10 generates heat through the principle of ohmic dissipation, serving as a heating element in the high-voltage assembly. An alumina tube 11 is placed inside the rhenium cylinder 10, which supports the heating element structure under high pressure. The rhenium cylinder 10 is formed by rolling a rhenium sheet with a length of approximately 6.9 mm, a width of approximately 4.0 mm, and a thickness of approximately 25.0 μm into a closed cylinder with a diameter of 1.2-1.3 mm and a height of 1.9-2.1 mm. The rhenium sheet is first rolled into a tube with a diameter of approximately 1.2-1.3 mm, and then wound about 1.5 turns radially around the tube; the upper and lower bottom surfaces of the cylinder are formed by bending the tube wall inward. The closed cylinder can be pre-pressed with a mold to smooth its surface morphology, and the height and dimensions of the cylinder can be adjusted. The diameter of the rhenium cylinder 10 should be slightly smaller than the inner diameter of the zirconia tube 8 to allow sufficient space for the two poles of the thermocouple 13. The rhenium cylinder 10 serves to conduct current and heat the sample chamber 12.

[0036] In one embodiment of the present invention, the alumina tube 11 preferably has an outer diameter of 1.2 mm, an inner diameter of 0.8 mm, and a height of approximately 2.0 mm; the cavity inside the alumina tube 11 is a sample cavity 12 for filling the sample. Preferably, the alumina tube 11 is made of alumina material with a bulk modulus of approximately 240 GPa.

[0037] The sample cavity 12 can accommodate cylindrical samples with a maximum diameter of 0.8 mm and a height of 2.0 mm. The size of the sample cavity 12 can be adjusted according to specific experimental needs. For experimental conditions with high pressure and temperatures below 1000 degrees Celsius, the alumina tube 11 can be omitted, and the entire cavity inside the rhenium cylinder 10 can be used to accommodate the sample.

[0038] As an embodiment of the present invention, thermocouple 13 is preferably type C (W). 97 Re3–W 75 Re 25 ) or D type (W 95 Re5–W 74 Re 26 Thermocouple 13, with a diameter of 0.1 mm. The positive and negative terminals of thermocouple 13 are connected to rhenium cylinder 10 for conduction.

[0039] In one embodiment of the present invention, copper wire 15 is wound around the thermocouple 13 at positions corresponding to the pressure-transmitting medium octahedron 5 and pyrophyllite sheet 4. The copper wire 15 is preferably a high-purity copper wire with a diameter of 0.1 mm and no insulating varnish, wound spirally around the thermocouple 13 wire to protect the thermocouple 13. The two poles of the thermocouple 13 are bent for approximately 0.7 mm between the third zirconia tube 8 and the rhenium cylinder 10, ensuring good contact and conductivity between the two poles of the thermocouple 13 and the rhenium cylinder 10, forming a temperature measurement circuit based on the Seebeck effect.

[0040] As an embodiment of the present invention, the copper wire 15 is preferably a copper coil with a length of about 4.0 mm, which protects the thermocouple 13 from being crushed or torn by the hard ceramic material under high voltage.

[0041] The tungsten carbide anvil assembly for generating ultra-high pressure provided by this invention can be applied to the generation of ultra-high pressure in multi-faceted anvil large-cavity presses. It develops a hard, uniformly granulated tungsten carbide anvil suitable for generating ultra-high pressure. The anvil 1 is machined with a 1.5mm side length and a one-degree chamfered wedge surface. A uniformly sized, dedicated chamfered pyrophyllite sheet 4 is designed as the sealing edge. Hard ceramic chromium oxide-doped magnesium oxide octahedron is used as the pressure transmission medium, and a high-hardness ceramic zirconia tube is used as the heat insulation material. A rhenium cylinder 10 is used as the heating element. An alumina tube 11 is placed inside the rhenium cylinder 10 to provide structural support for the heating element. Balsa wood blocks and epoxy resin boards 14 fix the initial position of the anvil assembly. Stable loading and high-temperature generation of ultra-high pressure are achieved, successfully generating a pressure of 40 GPa at high temperatures.

[0042] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] Example 1

[0044] The tungsten carbide anvil assembly provided by this invention was calibrated at room temperature. The actual calibration assembly used, which does not require heating, differs only in the assembly method within the octahedral cavity; other parameters remain the same as described above. A schematic diagram of the octahedral cavity assembly is shown below. Figure 3 The illustration in the upper right corner shows a schematic cross-sectional view of the pressure calibration experiment assembly using a zirconium wire at room temperature. A 100μm thick high-purity zirconium wire, preferably approximately 4mm long and less than 1mm wide, is placed at the center of an octahedron with a side length of 6.0mm. Four copper wires are connected to both ends of the zirconium foil to guide the electrical signal to the four surfaces of the octahedron for in-situ resistance observation of the zirconium sheet under high voltage. The pressure generation efficiency of the tungsten carbide anvil assembly is mainly affected by the mechanical properties of the anvil, the size of the anvil surface, and the size of the octahedron, the pressure-transmitting medium. Modifications to the internal assembly method of the octahedron do not affect the pressure generation efficiency of the tungsten carbide anvil assembly at room temperature.

[0045] The assembled tungsten carbide anvil assembly is placed into a multi-faceted anvil large-cavity press. In this embodiment, a Walker-type Max Voggenreiter, LPR1000-400 / 50 six-eight-die high-pressure device is used to extrude the anvil assembly composed of eight tungsten carbide anvils 1. During the pressure application process, the change in resistivity of the pressurized material is observed in situ.

[0046] Using a hard anvil 1 with a 1° chamfer (inclination angle), two discontinuous changes in electrical resistance of metallic zirconium under high pressure were successfully observed, such as... Figure 3 These correspond to the α-ω phase transition of zirconium at 8 GPa and the ω-β phase transition at 34.5 GPa, respectively. The ω-β phase transition occurs under an external load of approximately 4.5 MN. This demonstrates that a tungsten carbide hard anvil 1 with a 1° chamfer and a 1.5 mm side length anvil and its assembly can achieve an ultra-high pressure of 34.5 GPa at room temperature. Figure 4 As shown, by summarizing the relationship between the phase transition points of zirconium and other standard pressure materials and the external loading pressure (oil pressure), the pressure correction curve of the tungsten carbide anvil assembly provided by this invention at room temperature can be fitted, and the pressure generation efficiency of the assembly can be further analyzed and compared. Figure 4 The solid line represents the curve of the actual pressure of the tungsten carbide anvil with a 1° chamfer as a function of oil pressure in Example 1. The circular dots represent the pressure calibration values ​​of Example 1 at room temperature, and the pentagram dots represent the pressure calibration values ​​of Example 1 at high temperature.

[0047] Comparative Example 1

[0048] Referring to Example 1, the tungsten carbide anvil 1 was replaced with a cubic anvil without the 1° chamfered wedge surface (a 1° inclined surface) machining, and the anvil face side length was 1.5 mm, consistent with Example 1. The assembly method inside the octahedral cavity was consistent with Example 1. The assembly was placed in a Walker-type high-pressure device, and under an external load of up to 7.5 MN, no ω-β phase transition of zirconium at 34.5 GPa was observed. Figure 4 The phase transition points of other standard pressure materials in the same assembly proved that the cubic hard tungsten carbide anvil without 1° chamfering could not reach the phase transition pressure of 34.5 GPa, and its overall pressure generation efficiency was lower than that of anvil 1 with 1° chamfering. Figure 4 The dashed line represents the curve of the actual pressure in the cavity of Comparative Example 1 as a function of oil pressure, and the square points represent the pressure calibration values ​​of Comparative Example 1 at room temperature.

[0049] Example 2

[0050] The tungsten carbide anvil assembly technology provided by this invention was subjected to high-temperature pressure calibration. The actual pressure calibration assembly used was compared with... Figure 1The assembly shown is consistent. This embodiment uses a Walker-type Max Voggenreiter, LPR1000-400 / 50 six-eight-module high-voltage device.

[0051] Mg3Al2Si3O 12 A mixture of glass and MgAl2SiO6 oxides was used as the initial material to fill sample cavity 12. The assembled tungsten carbide anvil 1 was placed into a Walker-type high-pressure device, and the pressure correction curve at room temperature (e.g.) was used. Figure 4 The pressure was increased to 600 bar (approximately 9.0 MN) over 31.7 hours, and the sample was heated to 1950°C using a rhenium cylinder 10, held at that temperature for 1 hour, and then quenched. The pressure was then slowly released to atmospheric pressure over 30 hours. The surface of the depressurized sample was polished using polishing paper with 0.5 micrometer particles, and the polished surface was subjected to electron probe microanalysis (EPMA) for surface morphology and composition analysis.

[0052] like Figure 5 Backscattered electron microscopy (BSEM) images of the minerals showed that only Bridgmanite MgSiO3 was observed in the synthesized samples; corundum was not found, possibly because the corundum grain size exceeded the resolution of the scanning electron microscope (SEM) or was lost in the gaps. EPMA testing results showed that the Al2O3 content in the Bridgmanite MgSiO3 grains in the synthesized samples at 600 bar and ~1950 K was 20.95 ± 0.21 wt%, indicating that the sample cavity 12 reached an ultra-high pressure environment of at least ~40.4 ± 0.4 GPa. Specific data analysis methods referenced the calibration results of the high-temperature and high-pressure phase diagram of the MgSiO3-Al2O3 system.

[0053] Based on the comparative analysis of the above experimental results, the tungsten carbide anvil assembly provided by this invention, which uses a tungsten carbide cemented carbide anvil with a one-degree chamfered wedge surface, has a significant advantage in pressure generation efficiency compared to a tungsten carbide cemented carbide anvil without a one-degree chamfered wedge surface. Combined with the octahedral cavity assembly involved in this invention, it can achieve a breakthrough in the temperature and pressure range of 40 GPa and 1950 K, realize the synthesis of lower mantle minerals such as brigmanite with an alumina content of more than 20 wt.%, and observe the ω-β phase transition of zirconium at 34.5 GPa at room temperature.

[0054] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A tungsten carbide anvil assembly for generating ultra-high pressures, characterized by: The application relates to a high-pressure cubic anvil device, which comprises eight tungsten carbide cubic anvils, eight said anvils are assembled into a regular cube, two opposite surfaces of two adjacent said anvils are outwardly inclined from one end close to the center of the regular cube to one end far from the center of the regular cube, so that a trapezoidal gap is formed between the two adjacent said anvils, one end of the trapezoidal gap is directed to the center of the regular cube, two support blocks are supported in each said trapezoidal gap, each said anvil is cut into an equilateral triangle section as a pressure generating surface at the vertex position of the anvil towards the center of the regular cube, each said surface surrounds an octahedral cavity, three inclined surfaces around each said surface are fixedly connected with a talc leaf as a high-pressure sealing edge in close proximity to the edge of the surface, the octahedral cavity is sealed, an octahedral pressure transmitting medium is arranged in the octahedral cavity, first through holes are arranged in the centers of two opposite surfaces of the octahedral pressure transmitting medium, second through holes are arranged in the centers of two opposite edges of the octahedral pressure transmitting medium, a first zirconia tube, a third zirconia tube and a second zirconia tube are sequentially arranged in the first through holes in the axial direction, molybdenum column electrodes are arranged in the first zirconia tube and the second zirconia tube, a hollow rhenium cylinder is arranged in the third zirconia tube, the two molybdenum column electrodes are connected with two ends of the rhenium cylinder respectively, an alumina tube is arranged in the rhenium cylinder, a sample cavity is arranged in the alumina tube, two stages of thermocouples are respectively inserted into the second through holes on the two sides of the rhenium cylinder, the two stages of thermocouples respectively pass through the third zirconia tube and contact with the rhenium cylinder, and the temperature of the rhenium cylinder is measured. The average particle size of the anvil is 0.37 mu m, the standard deviation of the particle size distribution is 0.11 mu m, the cobalt binder content is 4.0 wt.%, the Rockwell hardness is 93.5 HRA, the side length is 25.4 mm, the inclination angle of the three inclined surfaces around the surface is 1 DEG, and the side length of the surface is 1.5 mm.

2. The tungsten carbide anvil assembly for generating ultra-high pressure according to claim 1, wherein: The support block is a balsa wood block, the balsa wood block is a cuboid wood block with a bottom surface side length of 5.0 mm and a height of 2.9 mm, the two support blocks in each trapezoidal gap are bonded on one of the anvils and are symmetrically arranged with respect to the diagonal of the inclined surface of the surface, and each support block is symmetrically arranged with respect to the other diagonal of the inclined surface.

3. The tungsten carbide anvil assembly for generating ultra-high pressures of claim 2, wherein: The cross section of the talc leaf is an isosceles trapezoid with a bottom angle of 45 DEG, the upper bottom edge of the isosceles trapezoid is 2.9 mm long, the upper bottom edge is chamfered by 54 DEG 44' 8.15" towards the inner side of the talc leaf, the angle is half of the dihedral angle of the pressure transmitting medium octahedron, the thickness of the talc leaf is 1.0 mm+ / -0.02 mm, and the width of the talc leaf is 3.0 mm.

4. The tungsten carbide anvil assembly for generating ultra-high pressure according to claim 2, wherein: An insulating heat-resistant adhesive tape is bonded on each of the three inclined surfaces around the surface; the outer surfaces of the four anvils in each outer surface of the regular cube are fixedly bonded by an epoxy resin plate, and the epoxy resin plate is an epoxy resin square sheet with a side length of 48 mm and a thickness of 0.4 mm.

5. The tungsten carbide anvil assembly for generating ultra-high pressures of claim 1, wherein: The pressure transmission medium octahedron is a chromium oxide doped magnesium oxide ceramic material with a Vickers hardness of 400 MPa; the first zirconia tube, the second zirconia tube and the third zirconia tube are made of a hard ceramic material with a Vickers hardness of 600 MPa and containing calcium oxide as a stabilizer.

6. The tungsten carbide anvil assembly for generating ultra-high pressure according to claim 2, wherein: The first through hole has a diameter of 2.0 mm, and the second through hole has a diameter of 0.5 mm; the first zirconia tube and the second zirconia tube have an outer diameter of 2.0 mm and an inner diameter of 1.5 mm, and the third zirconia tube has an outer diameter of 2.0 mm and an inner diameter of 1.5 mm; the third zirconia tube is provided with a through hole with a diameter of 0.3 mm at the center of the tube wall on both sides, for passing the two poles of the thermocouple; the molybdenum column electrode has a diameter of 0.5 mm; and the rhenium cylinder is a closed cylinder with a bottom diameter of 1.2-1.3 mm and a height of 1.9-2.1 mm.

7. The ultra-high pressure tungsten carbide anvil assembly of claim 1, wherein: The thermocouple is wound with a copper wire with a diameter of 0.1 mm at positions corresponding to the pressure transmission medium octahedron and the phlogopite sheet, and the copper wire is not provided with insulating paint.

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