A high pressure ultrasonic measuring device for a two-sided top press

Abstract

The present application combines ultrasonic measurement with a two-sided top press to provide a two-sided top press high-pressure ultrasonic measurement device. The device includes an upper press anvil, a lower press anvil, a high-pressure assembly, a transducer sheet, an ultrasonic signal generator, and an oscilloscope. The buffer rod of the high-pressure assembly is located in the lower press anvil groove, the top of the buffer rod is the sample to be pressed, the sample is surrounded by and on top of the cushioning material of the high-pressure assembly, the transducer sheet is pasted on the convex part on the back of the lower press anvil corresponding to the lower press anvil groove, and the transducer sheet is connected with the ultrasonic signal generator and the oscilloscope. The ultrasonic signal generator sends out a pulse voltage signal which is converted into an ultrasonic signal by the transducer sheet, and then passes through the press anvil, the buffer rod, and the sample, generates a return wave at the interface and returns to the transducer sheet, is sampled by the oscilloscope, and completes the ultrasonic measurement of the high-pressure material. The present application not only realizes high-pressure ultrasonic experiments, but also can be combined with a neutron line station to simultaneously obtain the transverse wave and longitudinal wave sound velocities of the material under high pressure and the neutron diffraction spectrum.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of static high pressure, and particularly relates to a high-pressure ultrasonic measuring device of a two-sided anvil press. BACKGROUND

[0002] A two-sided anvil press large-cavity press has the advantages of simple operation and low experimental cost compared with a multi-sided anvil large-cavity press, and is widely used in high-pressure synthesis and X-ray / neutron / optical in-situ characterization. Sound wave is a mechanical wave, and transmits mechanical vibration. Sound wave can be approximately regarded as the propagation of small disturbance of medium deviating from the equilibrium state, and the propagation speed of the disturbance in the medium is the sound speed. The sound speed reflects the compressibility of the medium when the medium is disturbed by sound, that is, the density change characteristic caused by stress or pressure. Through the sound speed measurement under high pressure, the changes of various elastic moduli with pressure and temperature can be obtained, which provides a scientific reference for the use of substances under different temperature and pressure conditions. Therefore, the application of high-pressure ultrasonic measurement to the two-sided anvil press can not only obtain the sound speed characteristics of the material under high pressure, realize the in-situ monitoring of the changes of the pressure, density / lattice volume and transverse wave and longitudinal wave sound speed of the sample, but also realize the effective control of the sealing pad and sample rheology, obtain higher pressure values, obtain large-volume samples, and obtain the neutron diffraction spectrum of the sample under high pressure in combination with neutron diffraction, and then smoothly carry out high-temperature and high-pressure in-situ neutron diffraction experiments.

[0003] P. Lheureux et al. first carried out high-pressure ultrasonic measurement on Paris-Edinburgh two-anvil press, the maximum pressure reached 6 GPa (Ultrasonics 38 2000 247-251). Until 2015, M. K. Jacobsen et al. realized the synchronous measurement of X-ray diffraction and ultrasonic on two-anvil press, using Boron epoxy (BE) as the gasket material, the maximum pressure was also 6 GPa (Review of Scientific Instruments 86 2015 113904). In addition, Y. Kono et al. used ZrO2 as the pressure transmission medium and BE as the gasket material, realized the synchronous measurement of X-ray diffraction and ultrasonic at 6.8 GPa and 500℃ (Review of Scientific Instruments 83 2012 033905). However, the assemblies used for X-ray diffraction and neutron diffraction experiments are completely different, for example, the Boron epoxy used for X-ray diffraction experiments cannot be applied to neutron experiments. Because Boron is a strong neutron absorbing material, and the hydrogen atoms in epoxy will produce incoherent scattering, which seriously affects the collection of neutron diffraction spectrum. In addition, the two-anvil high-pressure ultrasonic experiments of P. Lheureux, M. K. Jacobsen and Y. Kono et al. are based on conoidal anvil, so the maximum pressure is generally not more than 7 GPa. The present application is based on the idea of simultaneously carrying out high-pressure neutron diffraction and ultrasonic, and the assembly is redesigned, and the assembly is based on single-toroidal anvil, and the maximum pressure can reach more than 15 GPa. SUMMARY

[0004] To achieve this purpose, a two-anvil press high-pressure ultrasonic measurement device is provided.

[0005] A two-anvil press high-pressure ultrasonic measurement device, comprising an upper anvil, a lower anvil, a high-pressure assembly, a transducer, an ultrasonic signal generator and an oscilloscope.

[0006] The upper anvil and the lower anvil are concave curved anvils, and the concave curves of the anvil end faces are mirror-symmetrically arranged; a lower anvil groove with a flat bottom is arranged at the center position of the anvil end face of the lower anvil, a protruding part is arranged at the corresponding position of the back surface of the lower anvil, a double-emission-mode transducer is pasted on the protruding part, the transducer is connected with the ultrasonic signal generator and the oscilloscope, the ultrasonic signal generator and the oscilloscope are signal generation and data reading devices respectively; wherein the material of the lower anvil is tungsten carbide, and the bottom surface of the lower anvil groove and the pasting surface of the transducer pasted on the protruding part are mirror-polished;

[0007] The high-pressure assembly is located between the upper anvil and the lower anvil, and the overall shape of the high-pressure assembly matches the end surface shape of the upper anvil and the lower anvil; the high-pressure assembly comprises a buffer rod and a cushioning material, the buffer rod is arranged in the lower anvil groove, the top center position of the buffer rod is placed with the sample to be pressed, the sample is surrounded by the cushioning material, and the cushioning material and the buffer rod provide a hydrostatic pressure environment for the sample when the upper anvil and the lower anvil press from top to bottom; the contact surface between the buffer rod and the sample, the contact surface between the sample and the cushioning material, the bottom surface of the lower anvil groove, and the bonding surface of the convex part and the transducer sheet are parallel to each other;

[0008] The ultrasonic signal generator generates a sinusoidal pulse voltage, which is converted into an ultrasonic signal by the transducer, and the ultrasonic signal is transmitted to the buffer rod, the sample, and the cushioning material through the lower anvil, and the contact surface between the buffer rod and the sample and the contact surface between the sample and the cushioning material generate echoes, and then the echoes are transmitted back to the transducer sheet through the sample, the buffer rod, and the lower anvil, the transducer sheet converts the detected returned ultrasonic signal into an electrical signal, and the oscilloscope samples and calculates to complete the high-pressure in-situ sound velocity measurement.

[0009] Optionally, the transducer sheet is a LiNbO3 wafer, and the bonding plane mirror surface of the LiNbO3 wafer on the convex part is polished to a requirement of less than or equal to 1 μm.

[0010] Optionally, the distance between the bottom surface of the lower anvil groove and the transducer sheet is required to be not less than 15 mm.

[0011] Optionally, the outer periphery of the convex part and the back surface of the lower anvil are further provided with an annular gasket, the annular gasket is used to apply a force to the lower anvil, and the annular gasket does not generate a force to the convex part.

[0012] Optionally, the contact surface between the buffer rod and the bottom surface of the lower anvil groove and the contact surface between the buffer rod and the sample need to be polished to ensure that the ultrasonic signal is not attenuated due to diffuse reflection.

[0013] Optionally, a 2.5 μm thick gold foil is arranged between the buffer rod and the bottom surface of the lower anvil groove, between the buffer rod and the sample, and between the sample and the cushioning material.

[0014] Optionally, the frequency of the sinusoidal pulse voltage generated by the ultrasonic signal generator is 25-70 MHz, and the period is 5; the sampling step length of the oscilloscope is set to 5 GS / s.

[0015] Optionally, the material of the buffer rod is high-density aluminum oxide or silicon carbide, and the material of the cushioning material is tin, polytetrafluoroethylene, or sodium chloride.

[0016] Optionally, the lower anvil end face is provided with a lower outer platform connected with the lower curved concave ring in addition to the lower anvil concave groove, lower inner platform and lower curved concave ring arranged radially from the center; the upper anvil end face is provided with an upper outer platform connected with the upper curved concave ring in addition to the upper anvil concave groove, upper inner platform and upper curved concave ring arranged radially from the center; the upper outer platform and the lower outer platform are lower in height than the upper inner platform and the lower inner platform, and are narrower in width than the upper inner platform and the lower inner platform, so as to prevent the composite gasket in the high-pressure assembly from continuing to flow outward under high pressure; the high-pressure assembly further comprises a composite gasket and a pressure transmission medium, the pressure transmission medium transmits pressure to the sample and the gasket material through plastic flow under high pressure to complete the pressurization of the sample; the pressure transmission medium comprises an upper pressure transmission medium, a middle pressure transmission medium and a lower pressure transmission medium; the lower pressure transmission medium is located outside the buffer rod and in the lower anvil concave groove and is flush with the lower anvil concave groove; the upper pressure transmission medium is located in the upper anvil concave groove and is flush with the upper anvil concave groove; the middle pressure transmission medium is located outside the buffer rod and the gasket material and between the upper and lower anvils; the composite gasket is arranged outside the pressure transmission medium and serves as a lateral support for the pressure transmission medium; the composite gasket comprises an upper gasket, a lower gasket and a ceramic gasket made of titanium-zirconium alloy, the upper gasket and the lower gasket are arranged in a mirror image, and the ceramic gasket is located between the upper gasket and the lower gasket; the middle pressure transmission medium bears the pressure of the upper and lower inner platforms together with the upper and lower gaskets, and part of the upper and lower gaskets is located in the upper and lower curved concave rings.

[0017] Optionally, the pressure transmission medium is made of magnesium oxide, zirconium oxide or pyrophyllite, or a composite of several materials; the upper and lower gaskets are made of titanium-zirconium alloy, and the ceramic gasket is made of pyrophyllite.

[0018] The working process of the application is as follows: the upper and lower anvils of the two-sided anvil press drive the upper and lower anvils to pressurize the high-pressure assembly and the sample inside the high-pressure assembly, and after being loaded to a predetermined pressure, high-pressure sound velocity measurement is started. The ultrasonic signal generator is connected with the transducer through wires and outputs a sinusoidal pulse voltage to the transducer. Due to the piezoelectric effect, the crystal lattice of the transducer will vibrate under the action of the alternating current signal, thereby generating an ultrasonic signal of a corresponding frequency. The ultrasonic signal is transmitted through the lower anvil in the buffer rod and the pressurized sample, and echoes are generated at the interfaces of the anvil and the buffer rod, the buffer rod and the sample, and the sample and the gasket material, and the echoes return to the transducer along the original path. The transducer converts the vibrating ultrasonic signal into corresponding electrical signals, and the electrical signals are transmitted to an oscilloscope and recorded. The time difference of the echoes is Δt, which corresponds to the wave velocity of the back-and-forth propagation in the sample, and the sound velocity measurement of the sample under the loading pressure is completed.

[0019] The beneficial effects of the present application are: (1) the high-pressure ultrasonic measuring device based on the two-sided anvil press has the advantages of simple operation and low experimental cost compared with the traditional multi-sided anvil press high-pressure ultrasonic device; (2) the device can be directly combined with in-situ neutron diffraction characterization experiments to simultaneously obtain neutron diffraction spectra and sound velocity signals of the material under high pressure. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a structural schematic diagram of a two-sided anvil press high-pressure ultrasonic device;

[0021] Figure 2 is a schematic diagram of a high-pressure assembly structure;

[0022] In the figure: 1. upper anvil, 2. lower anvil, 3. high-pressure assembly, 4. transducer sheet, 5. ultrasonic signal generator, 6. oscilloscope, 7. sample, 8. ring gasket;

[0023] 11. upper anvil groove, 12. upper inner platform, 13. upper curved concave ring, 14. upper outer platform, 21. lower anvil groove, 22. protruding part, 23. lower inner platform, 24. lower curved concave ring, 25. lower outer platform, 31. buffer rod, 32. cushion material, 33. composite gasket, 34. pressure transmission medium;

[0024] 221. adhesive surface, 331. upper gasket, 332. lower gasket, 333. ceramic gasket, 341. upper pressure transmission medium, 342. middle pressure transmission medium, 343. lower pressure transmission medium. DETAILED DESCRIPTION

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0026] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application will be further described in detail below with specific embodiments and drawings.

[0027] Embodiment 1

[0028] As Figure 1 The structural schematic diagram of the two-sided anvil press high-pressure ultrasonic measuring device of the present application is shown, and from the figure, the two-sided anvil press high-pressure ultrasonic measuring device includes an upper anvil 1, a lower anvil 2, a high-pressure assembly 3, a transducer sheet 4, an ultrasonic signal generator 5 and an oscilloscope 6;

[0029] The upper and lower anvils 1 and 2 are concave curved disc-shaped anvils, and the middle part of the disc-shaped anvil is protruding and the edge part is relatively thin, which is convenient for neutron diffraction measurement. The concave curved surfaces of the upper and lower anvils are mirror-symmetrically arranged, and the high-pressure assembly 3 is arranged between the upper and lower anvils. The overall shape of the high-pressure assembly 3 matches the concave curved shape of the upper and lower anvils 1 and 2. Compared with the traditional anvil, the end surface of the lower anvil 2 is provided with a lower anvil groove 21, a lower inner platform 23 and a lower curved concave ring 24 in sequence from the center along the radial direction, and a lower outer platform 25 is arranged at the position outside the lower curved concave ring 24 and connected with the lower curved concave ring 24. Similarly, the end surface of the upper anvil 1 is provided with an upper anvil groove 11, an upper inner platform 12 and an upper curved concave ring 13 in sequence from the center along the radial direction, and an upper outer platform 14 is arranged at the position outside the upper curved concave ring 13 and connected with the upper curved concave ring 13. The upper and lower outer platforms 14 and 25 are lower in height and narrower in width than the upper and lower inner platforms 12 and 23, and the upper and lower outer platforms 14 and 25 can prevent the composite gasket 33 in the high-pressure assembly 3 from continuing to flow outward under high pressure.

[0030] A protruding part 22 is arranged at the position corresponding to the lower anvil groove 21 in the center of the back surface of the lower anvil 2, and a double-emission-mode transducer sheet 4 with a diameter of 3.23 mm and a thickness of 0.08 mm is attached to the protruding part 22. The double-emission-mode transducer sheet 4 can generate / receive longitudinal wave and transverse wave signals at the same time, and LiNbO3 wafer is selected as the transducer sheet 4 in the embodiment. In order to ensure that the LiNbO3 wafer is firmly attached to the protruding part and has good signal transmission, not only a suitable adhesive needs to be selected, but also the attachment surface of the protruding part and the lower anvil groove 21 need to be mirror-polished to 1 μm. The LiNbO3 wafer is connected with an ultrasonic signal generator 5 and an oscilloscope 6. The ultrasonic signal generator 5 and the oscilloscope 6 are signal generation and data reading devices respectively.

[0031] In order to have the function of a delay line, the lower anvil 2 is made of tungsten carbide. An annular gasket 8 is arranged on the outer periphery of the protruding part 22 and the back surface of the lower anvil 2, and is used to apply a force to the lower anvil 2. In order to ensure that the ultrasonic signal measurement is not affected under high pressure, the annular gasket 8 does not apply a force to the protruding part 22. The distance between the bottom surface of the lower anvil groove 21 and the transducer sheet 4 is not less than 15 mm, which can ensure that the echo of the transverse wave and the longitudinal wave are completely separated on the time axis.

[0032] Figure 2The structure of high pressure assembly is shown. The high pressure assembly 3 includes buffer rod 31 and cushion material 32, the buffer rod 31 is arranged in the lower anvil groove 21, the top center of the buffer rod 31 is placed the sample 7 to be pressed, the sample 7 is surrounded and the top is wrapped by the cushion material 32, the cushion material 32 and the buffer rod 31 provide hydrostatic pressure environment for the sample 7 when the upper and lower anvil presses. In order to ensure that the sample has a good hydrostatic pressure environment, the material of the buffer rod 31 is high density alumina or silicon carbide, and the cushion material 32 is soft tin, polytetrafluoroethylene or sodium chloride. In order to make the contact surface between the buffer rod 31 and the sample 7, the contact surface between the sample 7 and the cushion material 32, the bottom surface of the lower anvil groove 21 and the bonding surface of the convex part 22 and the transducer sheet 4 are parallel to each other; in order to ensure that the ultrasonic signal is not attenuated due to diffuse reflection, the contact surface between the buffer rod 31 and the bottom surface of the lower anvil groove 21 and the contact surface between the buffer rod 31 and the sample 7 need to be polished. In order to further increase the coupling, the contact surface between the buffer rod 31 and the bottom surface of the lower anvil groove 21 and the contact surface between the buffer rod 31 and the sample 7 can be put into 2.5μm thick gold foil.

[0033] The ultrasonic signal generator 5 generates a sinusoidal pulse voltage of 25-70MHz with a period of 5, which is converted into an ultrasonic signal by the transducer sheet 4, the ultrasonic signal is transmitted to the buffer rod 31, the sample 7 and the cushion material 32 through the lower anvil 2, the contact surface between the buffer rod 31 and the sample 7, the contact surface between the sample 7 and the cushion material 32 generates an echo, and then the sample 7, the buffer rod 31 and the lower anvil 2 transmit the echo back to the transducer sheet 4, the transducer sheet 4 converts the detected returned ultrasonic signal into an electrical signal, which is sampled and calculated by an oscilloscope to complete high pressure in-situ sound velocity measurement, wherein the sampling frequency is 5GS / s, that is, 50 billion points are collected per second, and the sampling time interval is 0.2ns.

[0034] The high-pressure assembly 3 further comprises a composite gasket 33 and a pressure transmission medium 34, the pressure transmission medium 34 transmits pressure to the gasket material 32 and the sample 7 by plastic flow under high pressure, and completes the pressurization of the sample 7; the pressure transmission medium 34 comprises an upper pressure transmission medium 341, a middle pressure transmission medium 342 and a lower pressure transmission medium 343; the lower pressure transmission medium 343 is located outside the buffer rod 31, in the lower anvil groove 21 and flush with the end face of the lower anvil groove 21; the upper pressure transmission medium 341 is located in the upper anvil groove 11 and flush with the end face of the upper anvil groove 11; the middle pressure transmission medium 342 is located outside the buffer rod 31 and the gasket material 32, between the upper and lower anvils; the composite gasket 33 is arranged outside the pressure transmission medium 34 and serves as a lateral support for the pressure transmission medium 34; the composite gasket 33 comprises an upper gasket 331, a lower gasket 332 and a ceramic gasket 333 made of titanium-zirconium alloy, the upper gasket 331 and the lower gasket 332 are arranged in a mirror image, and the ceramic gasket 333 is located between the upper gasket 331 and the lower gasket 332; the middle pressure transmission medium 342 together with the upper gasket 331 and the lower gasket 332 bears the pressure of the upper and lower inner platforms, and part of the upper gasket 331 and the lower gasket 332 is located in the upper curved concave ring 13 and the lower curved concave ring 24. The pressure transmission medium 34 is made of magnesium oxide, zirconium oxide or pyrophyllite, or a composite of several materials; the upper gasket 331 and the lower gasket 332 are made of titanium-zirconium alloy, and the ceramic gasket 333 is made of pyrophyllite.

[0035] The high-pressure ultrasonic measurement device of the two-sided anvil press in the embodiment can use a signal amplifier and a high-frequency duplexer to effectively amplify the ultrasonic wave signal and obtain recovered data with a better signal-to-noise ratio.

[0036] The high-pressure ultrasonic measurement device of the two-sided anvil press in the embodiment is assembled with low-back and neutron-diffraction-signal-free materials, and thus can be directly placed on a neutron scattering platform and combined with a neutron diffraction spectrometer to simultaneously obtain the neutron diffraction spectrum and the sound velocity of the material under high pressure, thereby realizing in-situ monitoring of the changes in pressure, density / lattice volume and transverse wave and longitudinal wave sound velocities of the sample.

[0037] The high-pressure ultrasonic measurement device of the two-sided anvil press in the embodiment can realize ultrasonic measurement under high temperature and high pressure by high-temperature and high-pressure assembly. The high-temperature and high-pressure assembly of the two-sided anvil press can realize a temperature and pressure condition of 15 GPa / 2000 K.

[0038] Compared with the ultrasonic device of a multi-sided anvil press, the high-pressure ultrasonic measurement device based on the two-sided anvil press has the advantages of simple operation and low experimental cost. The present application can not only realize high-pressure ultrasonic experiments, but also can be combined with in-situ neutron diffraction characterization experiments to simultaneously obtain the transverse wave, longitudinal wave sound velocity and neutron diffraction spectrum of the material under high pressure.

Claims

1. A high pressure ultrasonic measuring device for a two-sided top press, characterized in that, The application relates to an ultrasonic testing device, which comprises an upper anvil, a lower anvil, a high-pressure assembly, a transducer sheet, an ultrasonic signal generator and an oscilloscope; the upper anvil and the lower anvil are concave curved anvil faces which are arranged in mirror symmetry; the center of the anvil face of the lower anvil is provided with a lower anvil groove with a flat bottom, and the center of the back face of the lower anvil is provided with a convex part, a double-emission-mode transducer sheet is pasted on the convex part, the transducer sheet is connected with the ultrasonic signal generator and the oscilloscope, the ultrasonic signal generator and the oscilloscope are signal generation and data reading devices respectively; the material of the lower anvil is tungsten carbide, the bottom of the lower anvil groove and the pasting surface of the transducer sheet on the convex part are mirror-polished; the high-pressure assembly is located between the upper anvil and the lower anvil, the overall shape of the high-pressure assembly matches the shapes of the upper anvil and the lower anvil; the high-pressure assembly comprises a buffer rod and a cushioning material, the buffer rod is arranged in the lower anvil groove, the top center of the buffer rod is provided with a sample to be pressed, the sample is wrapped by the cushioning material, and the cushioning material and the buffer rod provide a hydrostatic pressure environment for the sample when the upper anvil and the lower anvil press; the contact surfaces between the buffer rod and the sample, between the sample and the cushioning material, the bottom of the lower anvil groove and the pasting surface of the transducer sheet are parallel to each other; the distance between the bottom of the lower anvil groove and the transducer sheet is not less than 15 mm; the outer periphery of the convex part and the back face of the lower anvil are further provided with an annular gasket, the annular gasket is used for applying a force to the lower anvil, and the annular gasket does not apply a force to the convex part; the contact surfaces of the buffer rod and the bottom of the lower anvil groove and the contact surface of the buffer rod and the sample need to be polished to ensure that the ultrasonic signal is not attenuated due to diffuse reflection.

2. The high pressure ultrasonic measuring device for two-sided roof press according to claim 1, characterized in that, The transducer sheet is a LiNbO3 wafer, and the mirror-polished pasting plane on the convex part is required to be less than or equal to 1 mu m.

3. The high pressure ultrasonic measuring device for two-sided roof press according to claim 1, characterized in that, Gold foils with a thickness of 2.5 mu m are arranged between the buffer rod and the bottom of the lower anvil groove, between the buffer rod and the sample and between the sample and the cushioning material.

4. The high pressure ultrasonic measuring device for two-sided roof press according to claim 1, characterized in that, The ultrasonic signal generator generates a sinusoidal pulse voltage with a frequency of 25-70 MHz and a period of 5; and the sampling step length of the oscilloscope is set to 5 GS / s.

5. The apparatus of claim 1, wherein, The material of the buffer rod is high-density alumina or silicon carbide, and the material of the cushioning material is tin, polytetrafluoroethylene or sodium chloride.

6. The high pressure ultrasonic measuring device for two-sided top press according to claim 1, characterized in that, The lower anvil end face is provided with a lower outer platform connected with the lower curved concave ring in addition to the lower anvil concave groove, lower inner platform and lower curved concave ring arranged radially from the center; the upper anvil end face is provided with an upper outer platform connected with the upper curved concave ring in addition to the upper anvil concave groove, upper inner platform and upper curved concave ring arranged radially from the center; the upper outer platform and lower outer platform are lower in height and narrower in width than the upper inner platform and lower inner platform, and can prevent the composite gasket in high-pressure assembly from continuing to flow outward under high pressure; the high-pressure assembly further comprises a pressure transmission medium and a composite gasket, the pressure transmission medium transmits pressure to the gasket material and sample through plastic flow under high pressure to realize pressurization of the sample; the pressure transmission medium comprises three parts of upper pressure transmission medium, middle pressure transmission medium and lower pressure transmission medium; the lower pressure transmission medium is located outside the buffer rod and in the lower anvil concave groove and is flush with the lower anvil concave groove; the upper pressure transmission medium is located in the upper anvil concave groove and is flush with the upper anvil concave groove; the middle pressure transmission medium is located outside the buffer rod and gasket material and between the upper and lower anvils; the composite gasket is arranged outside the pressure transmission medium and serves as lateral support for the pressure transmission medium; the composite gasket comprises upper and lower gaskets made of titanium-zirconium alloy and a ceramic gasket located between the upper and lower gaskets; the upper and lower gaskets are arranged in mirror image; the middle pressure transmission medium bears the pressure of the upper and lower inner platforms together with the upper and lower gaskets, and part of the upper and lower gaskets is located in the upper and lower curved concave rings.

7. The high pressure ultrasonic measuring device for two-sided top press according to claim 6, characterized in that, The pressure transmission medium is made of magnesium oxide, zirconium oxide or leaf talc, or a composite of several materials; the upper and lower gaskets are made of titanium-zirconium alloy, and the ceramic gasket is made of leaf talc.

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