High-temperature and high-pressure resistant carbon ring sealing structure

Abstract

The application discloses a high-temperature and high-pressure resistant carbon ring sealing structure and belongs to the technical field of carbon ring preparation, which is applied to hydrogen turbine expanders and other equipment that needs to realize reliable sealing in extreme environments, and comprises a full-surrounding inlay structure formed by a metal ring and a carbon ring, and a gradient transition layer is arranged between the metal ring and the carbon ring; the gradient transition layer comprises a metal bonding layer, a nano-composite buffer layer and a carbon diffusion layer which are arranged from inside to outside; the nano-composite buffer layer comprises ZrC / SiC nano-particle inlaid amorphous carbon matrix, and the thermal expansion coefficient is gradually changed from the value of the metal ring to the arithmetic average value of the two; and the carbon diffusion layer adopts vertically oriented growth nano-crystalline graphene sheets. The application can effectively solve the technical problems of the existing carbon ring sealing structure, such as large relative displacement, poor sealing performance, insufficient bonding strength and the inability to adaptively adjust the sealing effect according to the pressure under high-temperature and high-pressure working conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of sealing carbon ring preparation technical field, specifically to a kind of high temperature and high pressure carbon ring sealing structure, it is applied to hydrogen turbine expander and other equipment that needs to be reliably sealed in extreme environment. BACKGROUND

[0002] In industrial production, many equipment such as hydrogen turbine expander, etc., need to run in high temperature and high pressure harsh working conditions, which puts high requirements on sealing structure. The existing carbon ring sealing structure often faces many problems in high temperature and high pressure environment.

[0003] The utility model patent with publication number CN207880069U discloses an insulating sealing gasket resistant to high temperature and high pressure, comprising a ring-shaped metal framework, the two axial end faces of the metal framework are respectively provided with a ring-shaped groove recessed towards the inside, the axial end faces of the metal framework and the inner walls of the grooves are respectively provided with a first transition layer and a first insulating layer outward in turn, the gasket further comprises a sealing ring embedded in the groove, the outer surface of the sealing ring is higher than the outer surface of the first insulating layer, the first transition layer completely covers the axial end faces of the metal framework and the inner walls of the grooves, and the first insulating layer completely covers the first transition layer.

[0004] The utility model patent with publication number CN206608539U discloses a high-performance sealing gasket resistant to high temperature and high pressure and anticorrosion, which can be in the form of graphite reinforced composite gasket, graphite wave-tooth composite gasket or graphite metal winding gasket. The graphite reinforced composite gasket or graphite wave-tooth composite gasket is provided with a sealing protection ring made of metal plate and ceramic fiber belt layering in the inner layer. The graphite metal winding gasket comprises an inner ring, a sealing protection ring, a sealing ring and an outer ring arranged in turn from inside to outside, and the sealing protection ring is made of metal belt and ceramic fiber belt wound alternately. The sealing protection ring can effectively protect the area of graphite from oxidation, ensure the improvement of overall sealing effect, and make the sealing more reliable and durable.

[0005] The utility model patent with publication number CN202327099U discloses an ultra-high temperature and high pressure expansion graphite composite sealing gasket with metal guard ring, which comprises two or more layers of expansion graphite gasket, metal wire mesh is clamped between every two layers of expansion graphite gasket, and metal outer ring and metal inner ring guard ring are wrapped on the two end faces of the expansion graphite gasket respectively. The sealing gasket is used for connecting and sealing between the end interfaces of various high temperature and high pressure devices. After the interface is connected, the expansion graphite gasket is in a closed surrounding ring with metal outer ring and metal inner ring guard ring wrapped on the two end faces respectively. Once the expansion graphite sealing on the connected device fails under ultra-high temperature and high pressure, it will still be in the metal closed surrounding ring and will not leak out, so that the outside of the expansion graphite gasket can be in contact with the sealing part more effectively to meet the sealing requirements.

[0006] In practical applications, due to the large difference in the thermal expansion coefficients of the metal ring and the carbon ring, under the action of temperature and high pressure, the two are prone to relatively large displacement due to the different degrees of thermal expansion and cold contraction, resulting in an increase in the sealing gap, an increase in the leakage amount, and a decrease in the sealing performance. At the same time, the traditional sealing structure is difficult to adaptively adjust according to different sealing pressures, and the sealing effect is unstable when the pressure fluctuates. In addition, the combination strength of the metal ring and the carbon ring in the existing sealing structure is insufficient, and the transition layer is not reasonably designed, which further affects the service life and reliability of the sealing structure. SUMMARY

[0007] The purpose of the present application is to provide a high-temperature and high-pressure resistant carbon ring sealing structure, which can effectively solve the technical problems of the existing carbon ring sealing structure, such as large relative displacement, poor sealing performance, insufficient combination strength, and inability to adaptively adjust the sealing effect according to the pressure under high-temperature and high-pressure working conditions.

[0008] To solve the above technical problems, the technical solution adopted by the present application is:

[0009] A high-temperature and high-pressure resistant carbon ring sealing structure, comprising a full-enclosing inlaid structure formed by a metal ring and a carbon ring, and a gradient transition layer is arranged between the metal ring and the carbon ring.

[0010] The gradient transition layer comprises a metal bonding layer, a nano-composite buffer layer, and a carbon diffusion layer arranged from inside to outside.

[0011] The metal bonding layer is composed of 80-90wt% base metal and 10-20wt% Cr, and the thickness is 5-10μm.

[0012] The nano-composite buffer layer comprises ZrC / SiC nanoparticle inlaid amorphous carbon matrix, and the thermal expansion coefficient is transitioned from the value of the metal ring to the arithmetic mean value of the two.

[0013] The carbon diffusion layer adopts vertically oriented nanocrystalline graphene sheets.

[0014] Further, when used, under the working conditions of a temperature of 400-700℃ and a pressure of 15-40MPa, the relative displacement amount of the metal ring and the carbon ring is 0.01-0.02mm.

[0015] Further, the metal ring is internally provided with an annular magnetorheological fluid cavity, the cavity is filled with Fe3O4@SiO2core-shell nanoparticle magnetorheological fluid, and a magnetizing coil is arranged outside the metal ring.

[0016] When the sealing pressure is 15-25MPa, the magnetizing coil generates a 0.5-0.8T magnetic field to increase the viscosity of the magnetorheological fluid by 200-300%.

[0017] Further, when the sealing pressure is 15-25 MPa, the activation magnetic field strength of the excitation coil is adaptively adjusted with the sealing pressure difference in the range of 15-40 MPa.

[0018] Further, the carbon ring working surface is provided with a thermal deformation groove, when the temperature is 300-650℃, the groove depth increases to reduce the leakage flow passage cross-sectional area by 30-40%.

[0019] Further, the metal ring adopts Fe-40Ni-2Cr invar alloy with a thermal expansion coefficient of 1.0-1.5×10 -6 / K; the carbon ring adopts carbon fiber reinforced pyrolytic carbon composite material with a thermal expansion coefficient of 1.8-2.2×10 -6 / K.

[0020] Further, the inner surface of the metal ring is provided with 4-8 protrusions, and the outer surface of the carbon ring is provided with corresponding grooves, and the difference between the thermal expansion coefficients of the metal ring and the carbon ring is 1.0×10 -6 / K to 3.0×10 -6 / K.

[0021] Further, the protrusions are involute tooth-shaped protrusions.

[0022] Further, the curvature radius of the protrusions is 0.5-2.0mm, and the groove depth to protrusion height ratio is 1:1.05-1.10.

[0023] Further, the groove depth to protrusion height ratio is 1:1.08.

[0024] The application also discloses a preparation method of the high-temperature and high-pressure resistant carbon ring sealing structure.

[0025] a) laser cladding on the inner surface of the metal ring, power density 1.0×10 5 -1.5×10 5 W / cm 2 , Ar gas flow rate 10-20L / min;

[0026] b) magnetron sputtering deposition of a nano-composite buffer layer, target material ZrC-SiC, mass ratio 1:1-1:2, substrate bias -150--200V, deposition rate 0.5-1.0μm / h;

[0027] c) chemical vapor deposition of a carbon diffusion layer, C2H2 / Ar is introduced, volume ratio 1:5-1:8, temperature 850-900℃, heat preservation 2-4h.

[0028] The application also discloses an assembling method of the high-temperature and high-pressure resistant carbon ring sealing structure.

[0029] a) heating the metal ring to a temperature 40-60 DEG C higher than the working temperature;

[0030] b) embedding the carbon ring into the metal ring under inert gas environment, with the protrusions aligned with the grooves;

[0031] c) cooling down to room temperature at a rate of 2-5 DEG C / min, to form a fit with an interference of 0.025-0.035 mm.

[0032] In another aspect, the application also discloses an application of the high-temperature and high-pressure resistant carbon ring sealing structure, which is applied to a hydrogen turbine expander shaft seal, and the working temperature is -196 DEG C to 700 DEG C, the pressure is 1.0 Pa to 40.0 MPa, and the shaft rotation speed is 20,000-40,000 rpm, and the leakage rate is 0.5-1.0 sccm.

[0033] Compared with the prior art, the application has the following beneficial effects:

[0034] The gradient transition layer is arranged, the metal bonding layer enhances the bonding strength of the metal ring and the transition layer, the nano-composite buffer layer effectively solves the problem of large difference in thermal expansion coefficients between the metal ring and the carbon ring, the stress generated due to temperature change is reduced, the carbon diffusion layer promotes the combination with the carbon ring, the combination of the metal ring and the carbon ring is more firm, the stable structure can be maintained under high temperature and high pressure, and the relative displacement is reduced. Under the working condition of a temperature of 400-700 DEG C and a pressure of 15-40 MPa, the relative displacement amount of the metal ring and the carbon ring is only 0.01-0.02 mm, which is far lower than that of the prior art, and the stability of the sealing is significantly improved.

[0035] The annular magnetorheological fluid cavity in the metal ring and the excitation coil on the outer side are matched, when the sealing pressure is 15-25 MPa, the excitation coil generates a 0.5-0.8 T magnetic field to make the viscosity of the magnetorheological fluid increase by 200-300 %, the sealing performance can be adaptively adjusted according to the change of the sealing pressure, and the adaptability and reliability of the sealing structure under different pressure working conditions are enhanced.

[0036] The working surface of the carbon ring is provided with a thermal deformation groove, the leakage amount can be further reduced, and the sealing effect under the high-temperature working condition is improved. The metal ring is made of Fe-40Ni-2Cr invar alloy with a thermal expansion coefficient of 1.0-1.5 x 10 -6 / K, the carbon ring is made of carbon fiber reinforced pyrolytic carbon composite material with a thermal expansion coefficient of 1.8-2.2 x 10 -6 / K, and the difference between the thermal expansion coefficients of the two is controlled to be 1.0 x 10 -6 / K to 3.0 x 10 -6 / K, and the involute tooth-shaped protrusions on the inner surface of the metal ring and the corresponding grooves on the outer surface of the carbon ring are further matched, the structural deformation caused by the difference in thermal expansion is further reduced, and the stability of the overall structure is enhanced. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments will be briefly introduced as follows, and it should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0038] Figure 1 The whole structure schematic diagram of the high-temperature and high-pressure resistant carbon ring sealing structure.

[0039] Figure 2 The cross-sectional view of the present application. Figure 1

[0040] Figure 3 The local enlarged schematic diagram of A in the present application. Figure 2

[0041] Figure 4 The preparation process flow chart of the gradient transition layer in embodiment 1 of the present application.

[0042] Reference signs:

[0043] 101 metal ring, 102 carbon ring, 103 gradient transition layer, 104 metal bonding layer, 105 nanocomposite buffer layer, 106 carbon diffusion layer, 107 cavity, 108 excitation coil. DETAILED DESCRIPTION

[0044] In the following, only some exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the embodiments of the present application. Therefore, the drawings and the description are considered to be exemplary in nature rather than limiting. The following Figures 1-4 The embodiments of the present application are described in detail below.

[0045] Embodiment 1:

[0046] The present embodiment discloses a high-temperature and high-pressure resistant carbon ring sealing structure, which comprises a full-enclosing inlay structure formed by a metal ring 101 and a carbon ring 102, and a gradient transition layer 103 is arranged between the metal ring 101 and the carbon ring 102.

[0047] The gradient transition layer 103 comprises from inside to outside: a metal bonding layer 104 composed of 80wt% base metal and 20wt% Cr, with a thickness of 5μm; a nanocomposite buffer layer 105 which is an amorphous carbon matrix inlaid with ZrC / SiC nanoparticles, and the thermal expansion coefficient is transitioned from the value of the metal ring 101 to the arithmetic average value of the two; and a carbon diffusion layer 106 which is a vertically oriented nanocrystalline graphene sheet.​​

[0048] The metal ring 101 is internally provided with an annular magnetorheological fluid cavity 107, which is filled with Fe3O4@SiO2core-shell nanoparticle magnetorheological fluid, and the metal ring 101 is externally sleeved with an excitation coil 108.

[0049] The metal ring 101 is made of Fe-40Ni-2Cr invar alloy with a thermal expansion coefficient of 1.0×10 -6 / K; and the carbon ring 102 is made of carbon fiber reinforced pyrolytic carbon composite material with a thermal expansion coefficient of 1.8×10 -6 / K.

[0050] The inner surface of the metal ring 101 is provided with four involute tooth-shaped protrusions with a curvature radius of 0.5 mm, and the outer surface of the carbon ring 102 is provided with corresponding grooves with a groove depth to protrusion height ratio of 1:1.05, and the difference between the thermal expansion coefficients of the metal ring 101 and the carbon ring 102 is 0.8×10 -6 / K.

[0051] Under the working conditions of a temperature of 400℃ and a pressure of 15 MPa, the relative displacement amount between the metal ring 101 and the carbon ring 102 is 0.01 mm. When the sealing pressure is 15 MPa, the excitation coil 108 is activated to generate a 0.5 T magnetic field to increase the viscosity of the magnetorheological fluid by 200%. When the temperature is 300℃, the thermal deformation groove depth of the working surface of the carbon ring 102 increases to reduce the cross-sectional area of the leakage flow channel by 30%.

[0052] The metal ring 101 is internally provided with an annular magnetorheological fluid cavity 107, which is filled with Fe3O4@SiO2core-shell nanoparticle magnetorheological fluid, and the metal ring 101 is externally sleeved with an excitation coil 108. When the sealing pressure is in the range of 15-25 MPa, the excitation coil 108 is activated to generate a magnetic field of 0.5-0.8 T. Under the action of the magnetic field, the Fe3O4@SiO2core-shell nanoparticles in the magnetorheological fluid are orderly arranged, which significantly increases the viscosity of the magnetorheological fluid by 200-300%.

[0053] Referring to Figure 4 , in the preparation method of the high-temperature and high-pressure resistant carbon ring 102 sealing structure, the gradient transition layer 103 is prepared as follows:

[0054] a) laser cladding the inner surface of the metal ring 101, with a power density of 1.0×10 5 W / cm 2 , and an argon gas flow rate of 10 L / min;

[0055] b) magnetron sputtering deposition of a nanocomposite buffer layer 105, with a target material of ZrC-SiC, a mass ratio of 1:1, a substrate bias of -150 V, and a deposition rate of 0.5 μm / h;

[0056] c) Chemical vapor deposition of carbon diffusion layer 106, C2H2 / Ar (volume ratio 1:5) is introduced, temperature 850℃, holding time 2h.

[0057] In practical application, the specific assembly method is as follows: the metal ring 101 is heated to a temperature 40℃ higher than the working temperature; the carbon ring 102 is embedded into the metal ring 101 under inert gas environment, with the protrusions aligned with the grooves; the temperature is lowered to room temperature at a cooling rate of 2℃ / min, forming a fit with an interference of 0.025mm.

[0058] When the sealing structure is applied to the shaft seal of a hydrogen turbine expander, the leakage rate is 0.5sccm at a working temperature of-196℃, a pressure of 1.0Pa and a shaft rotating speed of 20,000rpm.

[0059] Example 2

[0060] The present embodiment discloses a high-temperature and high-pressure resistant carbon ring sealing structure, which comprises a full-enclosing inlaid structure formed by a metal ring 101 and a carbon ring 102, and a gradient transition layer 103 arranged between the metal ring 101 and the carbon ring 102. The gradient transition layer 103 comprises, from inside to outside: a metal bonding layer 104 composed of 85wt% base metal and 15wt% Cr, with a thickness of 7μm; a nanocomposite buffer layer 105 composed of ZrC / SiC nanoparticles inlaid in an amorphous carbon matrix, with a thermal expansion coefficient that transitions from the value of the metal ring 101 to the arithmetic mean value of the metal ring 101 and the carbon ring 102; and a carbon diffusion layer 106 composed of vertically oriented nanocrystalline graphene sheets.

[0061] The metal ring 101 is internally provided with an annular magnetorheological fluid cavity 107, which is filled with Fe3O4@SiO2core-shell nanoparticle magnetorheological fluid, and the metal ring 101 is externally provided with an excitation coil 108. The metal ring 101 is made of Fe-40Ni-2Cr invar alloy with a thermal expansion coefficient of 1.2×10 -6 / K; the carbon ring 102 is made of carbon fiber reinforced pyrolytic carbon composite material with a thermal expansion coefficient of 2.0×10 -6 / K. The inner surface of the metal ring 101 is provided with six involute tooth-shaped protrusions with a curvature radius of 1.2mm, and the outer surface of the carbon ring 102 is provided with corresponding grooves with a depth-to-height ratio of 1:1.08. The difference between the thermal expansion coefficients of the metal ring 101 and the carbon ring 102 is 0.8×10 -6 / K.

[0062] Under the working conditions of a temperature of 550℃ and a pressure of 27MPa, the relative displacement amount between the metal ring 101 and the carbon ring 102 is 0.015mm. When the sealing pressure is 20MPa, the excitation coil 108 generates a magnetic field of 0.65T to increase the viscosity of the magnetorheological fluid by 250%. The excitation magnetic field intensity of the excitation coil 108 and the sealing pressure difference of 27MPa, the piston cross-sectional area of 120mm 2The diameter of the magnetorheological fluid channel (1.2 mm) and the damping coefficient (1.0) are related. At a temperature of 475℃, the increased depth of the thermally deformed grooves on the working surface of the carbon ring 102 reduces the cross-sectional area of ​​the leakage channel by 35%.

[0063] In the fabrication method of this sealing structure, the gradient transition layer 103 is prepared by laser cladding of the inner surface of the metal ring 101 with a power density of 1.2 × 10⁻⁶. 5 W / cm 2 Ar gas flow rate 15 L / min; magnetron sputtering deposition of nanocomposite buffer layer 105, target material ZrC-SiC (mass ratio 1:1.5), substrate bias -175V, deposition rate 0.7 μm / h; chemical vapor deposition of carbon diffusion layer 106, C2H2 / Ar introduced, volume ratio 1:6, temperature 875℃, heat preservation for 3h.

[0064] The assembly method is as follows: heat the metal ring 101 to a temperature 50°C higher than the working temperature; insert the carbon ring 102 into the metal ring 101 in an inert gas environment, aligning the protrusion with the groove; cool down to room temperature at a cooling rate of 3.5°C / min to form an interference fit of 0.03mm.

[0065] When this sealing structure was applied to the shaft seal of a hydrogen turbine expander, the leakage rate was 0.7 sccm at an operating temperature of 300℃, a pressure of 20MPa, and a shaft speed of 30,000rpm.

[0066] Example 3:

[0067] This embodiment discloses a high-temperature and high-pressure resistant carbon ring sealing structure, comprising a fully enclosed embedded structure formed by a metal ring 101 and a carbon ring 102, with a gradient transition layer 103 between them. The gradient transition layer 103 consists of, from the inside out: a metal bonding layer 104, composed of 90wt% matrix metal and 10wt% Cr, with a thickness of 10μm; a nanocomposite buffer layer 105, which is an amorphous carbon matrix inlaid with ZrC / SiC nanoparticles, with the coefficient of thermal expansion transitioning from the value of the metal ring 101 to the arithmetic mean of the two; and a carbon diffusion layer 106, which is a vertically oriented nanocrystalline graphene sheet.

[0068] The metal ring 101 has an internal annular magnetorheological fluid cavity 107 filled with Fe3O4@SiO2 core-shell nanoparticle magnetorheological fluid. An excitation coil 108 is fitted around the outside of the metal ring 101. The metal ring 101 has a thermal expansion coefficient of 1.5 × 10⁻⁶. -6 / K Fe-40Ni-2Cr Invar alloy; carbon ring 102 with a thermal expansion coefficient of 2.2×10 -6 / K. The inner surface of the metal ring 101 is provided with eight involute tooth-shaped protrusions with a curvature radius of 2.0 mm, and the outer surface of the carbon ring 102 is provided with corresponding grooves with a groove depth to protrusion height ratio of 1:1.10. The difference between the thermal expansion coefficients of the metal ring 101 and the carbon ring 102 is 0.7*10 -6 / K.

[0069] Under the working conditions of a temperature of 700°C and a pressure of 40 MPa, the relative displacement amount between the metal ring 101 and the carbon ring 102 is 0.02 mm. When the sealing pressure is 25 MPa, the excitation of the excitation coil 108 generates a magnetic field of 0.8 T to make the viscosity of the magnetorheological fluid increase by 300%. The excitation magnetic field strength of the excitation coil 108 is associated with a sealing pressure difference of 40 MPa, a piston cross-sectional area of 200 mm 2 , a magnetorheological fluid channel diameter of 2.0 mm, and a damping coefficient of 1.2. When the temperature is 650°C, the thermal deformation groove depth of the working surface of the carbon ring 102 increases to reduce the cross-sectional area of the leakage flow channel by 40%.

[0070] In the preparation method of the sealing structure, the gradient transition layer 103 is prepared by: laser cladding the inner surface of the metal ring 101, with a power density of 1.5*10 5 W / cm 2 , an argon gas flow rate of 20 L / min; magnetron sputtering deposition of the nano-composite buffer layer 105, with a target material of ZrC-SiC (mass ratio 1:2), a substrate bias of -200 V, and a deposition rate of 1.0 μm / h; and chemical vapor deposition of the carbon diffusion layer 106, with the input of C2H2 / Ar (volume ratio 1:8) at a temperature of 900°C for 4 h.

[0071] The assembly method is: heating the metal ring 101 to a temperature 60°C higher than the working temperature; embedding the carbon ring 102 in the metal ring 101 in an inert gas environment, with the protrusions aligned with the grooves; and cooling at a rate of 5°C / min to room temperature to form a fit with an interference amount of 0.035 mm.

[0072] The sealing structure is applied to the shaft seal of a hydrogen turbine expander, with a working temperature of 700°C, a pressure of 40 MPa, and a shaft rotation speed of 40,000 rpm, and the leakage rate is 1.0 sccm.

[0073] Comparative Example 1

[0074] The graphite laminated sealing material (such as the LAMINATE PSM series) of the prior art is applied to the shaft seal of a hydrogen turbine expander, with a working temperature of 300°C, a pressure of 20 MPa, and a shaft rotation speed of 30,000 rpm, and the leakage rate is 5.0 sccm.

[0075] The test data of Examples 1-3 and Comparative Example 1 are as follows:

[0076] 1. Relative displacement amount test data:

[0077] The relative displacement amount of examples 1-3 and comparative example 1 was monitored continuously for 100 hours under the conditions of a temperature of 400-700 DEG C and a pressure of 15-40 MPa, and the results were as follows:

[0078] Example 1: under the condition of 400 DEG C / 15 MPa, the initial displacement was 0.01 mm, and after 100 hours, it was stabilized at 0.011 mm, and the fluctuation amplitude was less than or equal to 0.001 mm.

[0079] Example 2: under the condition of 550 DEG C / 27 MPa, the initial displacement was 0.015 mm, and after 100 hours, it was stabilized at 0.016 mm, and the fluctuation amplitude was less than or equal to 0.001 mm.

[0080] Example 3: under the condition of 700 DEG C / 40 MPa, the initial displacement was 0.02 mm, and after 100 hours, it was stabilized at 0.021 mm, and the fluctuation amplitude was less than or equal to 0.001 mm.

[0081] Comparative example 1: under the condition of 550 DEG C / 27 MPa, the initial displacement was 0.1 mm, and after 100 hours, it increased to 0.15 mm, and the fluctuation amplitude was 0.05 mm.

[0082] The displacement stability of the structure of the application under long-term high temperature and high pressure was 15 times that of comparative example 1, as measured by a laser displacement sensor (accuracy ± 0.001 mm).

[0083] 2. Leakage rate performance data:

[0084] In the hydrogen turbine expander shaft seal simulation experiment, the leakage rate test results under different conditions were as follows:

[0085] Operating parameters Example 1 Example 2 Example 3 Comparative Example 1 20000 rpm / 15 MPa 0.5 seem - - 4.8 seem 30000 rpm / 27 MPa - 0.7 seem - 5.0 seem 40000 rpm / 40 MPa - - 1.0 seem 5.5 seem

[0086] The leakage rate of the application was only 1 / 5-1 / 10 of that of comparative example 1 in the full operating range, as tested by the mass flow method (measurement accuracy ± 0.05 sccm), and the leakage rate increased by less than or equal to 0.1 sccm as the speed increased from 20,000 rpm to 40,000 rpm, while the increase of comparative example 1 was 0.7 sccm.

[0087] 3. Magnetorheological fluid performance experiment:

[0088] The magnetic field adjustment effect of the magnetorheological fluid of example 2 was tested:

[0089] Without a magnetic field: the base viscosity was 250 mPa·s, and the leakage amount of the sealing gap under a pressure of 15 MPa was 1.2 sccm;

[0090] 0.5T magnetic field (15MPa): viscosity rises to 750mPa·s, leakage rate drops to 0.6sccm;

[0091] 0.65T magnetic field (27MPa): viscosity rises to 980mPa·s, leakage rate drops to 0.3sccm;

[0092] 0.8T magnetic field (25MPa): viscosity rises to 1020mPa·s, leakage rate drops to 0.25sccm;

[0093] The measurement by a rotational viscometer (high-temperature and high-pressure cavity 107) shows that the sealing performance of the magnetorheological fluid can be precisely controlled by the magnetic field strength, and a dynamic sealing compensation is formed in the range of 15-25MPa.

[0094] 4. Verification of the effect of heat-induced deformation groove:

[0095] Test of the form and sealing effect of the groove on the working surface of the carbon ring 102 at different temperatures:

[0096] At 300℃: the groove depth increases from the initial 0.1mm to 0.13mm, the flow passage cross-sectional area decreases by 30%, and the leakage rate decreases by 28%.

[0097] At 475℃: the groove depth increases to 0.15mm, the flow passage cross-sectional area decreases by 35%, and the leakage rate decreases by 34%.

[0098] At 650℃: the groove depth increases to 0.17mm, the flow passage cross-sectional area decreases by 40%, and the leakage rate decreases by 39%.

[0099] Through scanning electron microscope observation of the groove form and fluid simulation calculation, it is proved that heat-induced deformation can self-adaptively compensate for the change of sealing gap at high temperature, and form a synergistic effect with the adjustment of magnetorheological fluid.

[0100] 5. Test data of bonding strength:

[0101] Test of the interface bonding performance of the gradient transition layer 103:

[0102] Shear strength of the metal bonding layer 104 and the metal ring 101: 85MPa for Example 1 and 32MPa for Comparative Example 1 (without transition layer).

[0103] Peeling strength of the carbon diffusion layer 106 and the carbon ring 102: 42N / cm for Example 3 and 15N / cm for Comparative Example 1.

[0104] Interface shear resistance at 700℃ high temperature: Example 2 retains 82% of the room temperature strength, and Comparative Example 1 only retains 45%.

[0105] The data show that the gradient transition layer 103 significantly improves the interface bonding strength and high-temperature stability of the dissimilar materials.

[0106] While the preferred embodiments of the application have been described, additional variations and modifications can be made to these embodiments by those skilled in the art once they have the benefit of the present disclosure. Therefore, the appended claims are intended to encompass all such variations and modifications as falling within the scope of the application.

[0107] The above descriptions are only the preferred embodiments of the present application, not intended to limit the present application. It should be pointed out that any modification, equivalent replacement and improvement within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A high-temperature and high-pressure resistant carbon ring sealing structure, characterized in that: It includes a fully enclosed mosaic structure formed by metal rings and carbon rings, with a gradient transition layer between the metal rings and the carbon rings; The gradient transition layer comprises a metal bonding layer, a nanocomposite buffer layer, and a carbon diffusion layer arranged from the inside out. The metal bonding layer is composed of 80-90wt% base metal and 10-20wt% Cr, with a thickness of 5-10μm; The nanocomposite buffer layer comprises an amorphous carbon matrix inlaid with ZrC / SiC nanoparticles, and the coefficient of thermal expansion transitions from the metal ring value to the arithmetic mean of the two. The carbon diffusion layer is made of vertically oriented nanocrystalline graphene sheets.

2. The high-temperature and high-pressure resistant carbon ring sealing structure according to claim 1, characterized in that: During use, under operating conditions of 400-700℃ and 15-40MPa, the relative displacement between the metal ring and the carbon ring is 0.01-0.02mm.

3. The high-temperature and high-pressure resistant carbon ring sealing structure according to claim 1, characterized in that: The metal ring has an annular magnetorheological fluid cavity inside, which is filled with Fe3O4@SiO2 core-shell nanoparticle magnetorheological fluid, and an excitation coil is sleeved on the outside of the metal ring.

4. The high-temperature and high-pressure resistant carbon ring sealing structure according to claim 3, characterized in that: When the sealing pressure is 15-25MPa, the activation magnetic field strength of the excitation coil is adaptively adjusted within the range of 15-40MPa according to the sealing pressure difference.

5. The high-temperature and high-pressure resistant carbon ring sealing structure according to claim 1, characterized in that: The working surface of the carbon ring is provided with thermally deformable grooves.

6. The high-temperature and high-pressure resistant carbon ring sealing structure according to claim 5, characterized in that: The metal ring has a thermal expansion coefficient of 1.0-1.5×10⁻⁶. -6 / K Fe-40Ni-2Cr Invar alloy; the carbon ring has a thermal expansion coefficient of 1.8-2.2×10 -6 / K carbon fiber reinforced pyrolytic carbon composite material.

7. A high-temperature and high-pressure resistant carbon ring sealing structure according to any one of claims 1-6, characterized in that: The inner surface of the metal ring has 4-8 protrusions, and the outer surface of the carbon ring has corresponding grooves.

8. The high-temperature and high-pressure resistant carbon ring sealing structure according to claim 7, characterized in that: The protrusion is an involute tooth-shaped protrusion.

9. The high-temperature and high-pressure resistant carbon ring sealing structure according to claim 8, characterized in that: The radius of curvature of the protrusion is 0.5-2.0 mm, and the ratio of the groove depth to the protrusion height is 1:1.05-1.

10.

10. The high-temperature and high-pressure resistant carbon ring sealing structure according to claim 9, characterized in that: The ratio of the groove depth to the protrusion height is 1:1.08.

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