Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D11/00—Preventing or minimising internal leakage of working-fluid, e.g. between stages
  • F01D11/02—Preventing or minimising internal leakage of working-fluid, e.g. between stages by non-contact sealings, e.g. of labyrinth type
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2230/00—Manufacture
  • F05D2230/40—Heat treatment
  • F05D2230/41—Hardening; Annealing
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2300/00—Materials; Properties thereof
  • F05D2300/10—Metals, alloys or intermetallic compounds
  • F05D2300/13—Refractory metals, i.e. Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W
  • F05D2300/132—Chromium
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2300/00—Materials; Properties thereof
  • F05D2300/20—Oxide or non-oxide ceramics
  • F05D2300/22—Non-oxide ceramics
  • F05D2300/228—Nitrides
  • F05D2300/2282—Nitrides of boron
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2300/00—Materials; Properties thereof
  • F05D2300/20—Oxide or non-oxide ceramics
  • F05D2300/22—Non-oxide ceramics
  • F05D2300/229—Sulfides
  • F05D2300/2291—Sulfides of molybdenum
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T50/00—Aeronautics or air transport
  • Y02T50/60—Efficient propulsion technologies, e.g. for aircraft

Definitions

• This disclosure relates, in general, to materials and applications for use in extreme temperature environments.
• sliding components such as linear or reciprocating applications including piston and rotor devices with components that are required are increasingly being required to operate in extreme environments.
• hydrodynamic face seals and hydrodynamic circumferential seals are sealing technologies that minimize lubrication oil leakage.
• Hydrodynamic seals offer an attractive solution since they operate primarily in a non-contacting manner, thus increasing seal life and reliability in a compact axial space while maintaining tight seal clearances.
• Both hydrodynamic face seals as well as hydrodynamic circumferential seals rely on the development of a pressure profile between a rotating and static sealing surface to generate an operating gap as small as possible. A good surface finish must be maintained on the rotating and static sealing surfaces in order to preserve the required pressure profile.
• hydrodynamic seals are non-contacting during the bulk of operation, they are subject to sliding contact during spin-up and shutdown of the rotor. To minimize wear and heat checking throughout contact operation, and consequently maintain a highly effective hydrodynamic seal, the seal components are generally made out of materials that exhibit excellent friction and wear characteristics.
• the present system provides, in one aspect, a sealing system for use in an oxidizing environment which includes a rotor and a sealing stator.
• the stator includes a solid lubricant or a surface treatment and the rotor is hardened or the stator is hardened and the rotor includes the solid lubricant or the surface treatment.
• the stator is located proximate to the rotor to provide a seal.
• the stator and the rotor are robust at extreme temperatures above 700 degrees Fahrenheit (F) such that at least one of the stator and the rotor have a wear rate and a surface roughness sufficient to maintain an operating gap between the stator and rotor.
• the present system provides, in one aspect, a sliding system for use in an oxidizing environment which includes a sliding portion and a sealing portion.
• the sealing portion includes a solid lubricant or a surface treatment and the sliding portion is hardened or the sliding portion includes the solid lubricant or the surface treatment and the sealing portion is hardened.
• the sealing portion is located proximate to the sliding portion to provide a seal.
• the sealing portion and the sliding portion are robust at temperatures above 700 degrees Fahrenheit (F) such that at least one of the sealing portion and the sliding portion have a wear rate and a surface roughness sufficient to maintain an operating gap between the sealing portion and the sliding portion.
• FIG. 1 is a side cross-sectional view of a hydrodynamic sealing system in accordance with an embodiment of the present system
• FIG. 2 is an enlarged view of a portion of the system of FIG. 1;
• FIG. 3 is a schematic of the operation of a hydrodynamic face seal in accordance with an embodiment
• FIG. 4 depicts a disc-on-ring test apparatus
• FIG. 5 is a table listing materials utilized in stators and rotors for testing according to the apparatus of FIG. 4;
• FIG. 6 is a plot of pre-test and post-test surface roughness for the rotor and stators of FIG. 5;
• FIG. 7 is a plot of pre-test and post-test weight change for the rotors and stators of FIG. 5;
• FIG. 8 is a plot of average torque during tests for the materials in FIG. 5;
• FIG. 9 lists tabular data for the tests according to the apparatus of FIG. 4 and materials of FIG. 5;
• FIG. 10 is a table of stators and rotors tested under Phase II testing;
• FIG. 11 is a plot of pre-test and post-test surface roughness for the rotors and stators of FIG. 10;
• FIG.12 is a plot of pre-test and post-test weight change for the rotors and stators of FIG. 10;
• FIG. 13 is a plot of average torque during the tests of the stators and rotors of FIG. 10;
• FIG. 14 is a table of results of the tests of the stators and rotors of FIG. 10;
• FIG. 15 is a top view of a piston and cylinder in accordance with an embodiment of the present system.
• FIG. 16 is a side cross-sectional view of the system of FIG. 15.
• One example is a coating or parent material that permits operation in the extreme environments, particularly for sliding elements.
• the sealing system provides a tight seal and maintains a small gap with low wear and surface roughness in a high temperature environment.
• a hydrodynamic sealing system 10 includes a rotor 20 coated with a hard coating and a seal 30 composed of a solid lubricant (e.g., Boronized Inconel 718) that is robust at temperatures exceeding 700 degrees Fahrenheit. In one example the temperature range goes up to about 1200 degrees Fahrenheit (F)).
• a solid lubricant e.g., Boronized Inconel 7128
• Robust is defined herein as having a wear rate and surface roughness sufficient to maintain an operating gap between the stator and rotor of about 0.0002 inches.
• Hydrodynamic face seals usually referred to as Dry Gas Seals in industries such as the Oil and Gas industry, consist of a rotating ring, known as a seat or rotor (e.g. rotor 20), and a stationary ring, known as the face or stator (e.g., seal 30).
• a rotating ring known as a seat or rotor (e.g. rotor 20)
• a stationary ring known as the face or stator (e.g., seal 30).
• the surface finish of each face seal is on the order of 0.1 ⁇ .
• the geometry of the rotor includes radial grooves 200 that extend from the center of the seal face to the outer diameter as depicted in FIG. 3.
• hydrodynamic seal portions may be separated (e.g., by an operating gap), and when separated, the seat (e.g. rotor 20) rides on a cushion of gas over the face (e.g., seal 30) as depicted in FIG. 3. As indicated above, the seal portions may contact each other during start-up and shut down of a particular rotor.
• the grooves of the seat are about 6 um deep and the face - seat gap is about 3 ⁇ .
• System 10 is an advanced hydrodynamic seal that is robust in an oxidizing environment at extreme temperatures, for example greater than 700 degrees
• a sealing system could be used in sumps (e.g., a sump 40) of a High Mach Turbo Aircraft Engine as depicted in FIGS. 1-2, for example.
• Sump 40 may include a bearing 50, a seal oil slinger 60, seal windback threads 70, and a seal housing 80.
• a stationary seal 90 and a rotating labyrinth seal 100 are also depicted.
• An operating gap 110 is present between seal 30 and rotor 20.
• Seal 30 may include a surface treatment, such as Boronized Inconel 718 that is robust over 1000 degrees Fahrenheit (F) and at temperatures up to at least 1200 degrees Fahrenheit (F).
• the suitable operation of a hydrodynamic seal requires a sealing surface that maintains a low surface roughness throughout operation.
• a hard rotor coating e.g., having a hardness Rockwell value of HRC 70 or more
• a seal component which includes an appropriate surface treatment (e.g., Boronized Inconel 718) results in a low coefficient of friction, a low wear rate, and the ability to retain an acceptable surface finish throughout operation.
• the rotor could include a surface treated material as described while the seal component could have a hard coating or may be otherwise hardened such that it has a hardness Rockwell value of HRC 70 or more.
• forward, mid, and aft sumps of a High Mach Turbo Aircraft Engines reach extreme temperatures of 1000 degrees Fahrenheit (F) to about
• Various substrates and coatings for sump seals were investigated for operating at 1200° degrees Fahrenheit (F).
• Parameters for hydrodynamic seals to be used in this environment include, for example: wear resistance at 1200 degrees Fahrenheit (F), low coefficient of friction and low heat generation at sliding interface.
• severe, degrading oxidation typically occurs at temperatures exceeding 700 degrees Fahrenheit (F) in traditional carbon seals. It is desirable that materials used in such seals survive at ranges of at least 700 degrees Fahrenheit (F), 1000 degrees Fahrenheit (F) and 1200 degrees Fahrenheit (F) to provide low leakage and are insensitive to an oil environment.
• the simulated testing predicted steady-state leakage (performance) based on operating regime, predicted thermal distortion and impact on performance, and characterized the effect of surface roughness on performance.
• High temperature material testing was performed on a sliding wear test rig as depicted in Fig. 4 including a rotor disk 130 and a stator ring 140 having a gap 150 therebetween.
• the sliding wear test rig was designed for ring-on-disc testing, where the rotor is rotating and the stator (seal) is stationary. This testing mimics the actual conditions (e.g., the temperature and speed) which occurs in a high temperature (e.g., up to 1200 degrees F) environment, such as a sump seal in a High Mach Turbo Aircraft Engine, during the start up and shut down of the engine, i.e., before or after the hydrodynamic lift occurs.
• a high temperature e.g., up to 1200 degrees F
• the seal in one example (the static stator of test setup) consisted of the materials listed in FIG. 5.
• a WC-Co coated Inconel 718 disc was tested against M-45 electrographite.
• a CrC-NiCr rotor coating (oxidation resistant up to 1650 degrees Fahrenheit (F)) replaced the presently used WC-Co coating (oxidation resistant up to 1000 degrees Fahrenheit (F)).
• FIG. 5 summarizes the materials tested in Task 3 and Task 4.
• Phase 1 The testing was separated into two phases (Phase 1 and Phase 2).
• Phase 2 testing was performed at multiple isotherms throughout the operating range of the component.
• Phase 1 testing was run at a linear speed of 275 ft/s (at the outer diameter of the test sample).
• the temperature at the sliding interface was 1000 degrees Fahrenheit (F).
• F degrees Fahrenheit
• the contact pressure was held at 3.5 psi, which is the typical contact pressure as specified by traditional seal vendors.
• the second phase of testing was also conducted at 275 ft/s at isotherms of 72 degrees Fahrenheit (F), 400 degrees Fahrenheit (F), 600 degrees Fahrenheit (F), 800 degrees Fahrenheit (F), 1000 degrees Fahrenheit (F), and 1200 degrees Fahrenheit (F).
• the specific test metrics to compare material performance were: 1) coefficient of friction data; 2) profilometry, to evaluate surface finish degradation as caused by wear and oxidation; 3) temperature levels at the sliding interface; and 4) mass loss (to evaluate wear).
• FIG. 6 is a plot of the pre-test and post-test surface roughness (in micro inches Ra) for Test 1 - Test 10 for the rotor and stators.
• FIG. 7 is a plot of the pre-test and post-test weight change for the rotor and stators, and
• FIG. 8 is a plot of the average torque during each of the tests.
• FIG. 9 lists the tabular data from the tests.
• Test 1 is the baseline test of the M-45 Electrographite stator versus a WC-Co rotor (current state of the art material combination). While the performance of this material combination was superior during the 1-hour wear test, the electrographite stator material oxidizes rapidly and is not suitable for long-term operation at the desired temperature.
• Test 2 material combination was not able to survive the operating conditions.
• the selected SiC material provides excellent wear characteristics
• Test 3 material combination of ESK Ekastic T Silicon Nitride and the CrCNiCr coated rotor provided the best test results from the non-baseline material combinations.
• the torque (friction) level for Test 3 is very similar to the Test 1 levels and the weight loss value for Test 3 is better than the Test 1 value.
• Phase 1 results from this material combination are very promising and it was selected to be tested under the Phase 2 operating conditions.
• the stator materials for Test 4 and Test 5 were partially composed of hexagonal boron nitride. This material has a low coefficient of friction (e.g., less than 0.2 above 1000 degrees Fahrenheit (F) while graphite's coefficient of friction increases dramatically (e.g., over 0.8) above this temperature. Despite the promising high temperature friction data for these materials, the Test 4 and Test 5 material combinations did not perform well under the Phase 1 test conditions. These materials were not selected for Phase 2 testing.
• Test 6 material combination of the Tribaloy T-800 coating and the CrC- NiCr coated rotor provided marginally successful results regarding surface roughness and weight loss.
• the torque (friction) level for Test 6 was higher than the remainder of the Task 4 coatings tested and was not selected for Phase 2 testing.
• Test 7 material combination of Boronized Inconel and the CrC-NiCr coated rotor provided marginally successful results regarding surface roughness considering the stator roughness increased more than desired. Despite this, the torque (friction) level for Test 7 was lower than the baseline torque from Test 1 (carbon graphite). This low torque level from this material combination is very promising and it was selected for Phase 2 testing.
• Test 8 material combination of an Alcrona coated stator and the CrC- NiCr coated rotor provided marginally successful results regarding surface roughness, weight loss, and torque. This material combination was not selected for Phase 2 testing.
• Test 9 material combination of NASA PS304 coated stator and the CrC- NiCr coated rotor provided excellent results regarding surface roughness and marginal results for weight loss.
• the torque (friction) level for Test 9 was lower than the baseline torque from Test 1 (carbon graphite). This low torque level and low roughness change for this material combination was selected for Phase 2 testing.
• Test 10 material combination of TiAl Alloy coated stator and the CrC- NiCr coated rotor provided marginally successful results regarding surface roughness, weight loss, and torque. This material combination was not selected for Phase 2 testing.
• FIG. 10 The material combinations presented in FIG. 10 were tested under Phase 2 Conditions, i.e., with a chamber temperature varied up to 1200 degrees Fahrenheit (F), a maximum surface speed at 275 ft/s, a load at the wearing surface at 3.5 psi, and a test duration of 1 hour.
• FIG. 11 is a plot of the pre-test and post-test surface roughness for the rotor and stators
• FIG. 12 is a plot of the pre-test and post test weight change for the rotor and stators
• FIG. 13 is a plot of the average torque during each of the tests.
• FIG. 14 presents the tabular data relative to tests 11, 12, 13 and 11a.
• Test 11 material combination of Boronized Inconel stator and the CrC- NiCr coated rotor was able to survive the full test matrix for Phase 2.
• the surface roughness and weight change experienced by the specimens are similar to what was measured during Phase 1.
• Fahrenheit (F) isotherm was 0.57in-lb which is much higher than the average torque measured at this same isotherm in Phase 1 testing (0.13in-lb). This offset may have been due to variations in the testing rig after a re-build thereof.
• Test 12 and Test 13 did not survive the test past the 72 degrees Fahrenheit (F) isotherm. Both tests were stopped due to an excessive run out in the test rig shaft. To ensure these failures were due to material performance and not due to the re-build of the test rig the Test 11 material combination was re-tested as Test 11 A. The data collected from 11 A compared very well to data from Test 11. This agreement confirms that the test rig did not contribute to the Test 12 and Test 13 failures.
• Boronized Inconel 718 and CrC-NiCr coated Inconel 718 are appropriate for the stator or seal (e.g., seal 30) and rotor (e.g., rotor 20), respectively.
• the average torque was lower than the other materials in test 11A, while the increase in roughness for Boronized Inconel 718 was the least of the other stators listed in FIG. 14.
• these materials used as discussed provided high temperature compatibility, good wear characteristics (gradual, as opposed to catastrophic), and the ability to maintain a good surface finish.
• Other appropriate materials for the stator include hexagonal boron nitride, and NASA PS304 coated Inconel 718.
• the quality of the NASA PS304 coating in the phase 2 testing was marginal due to the small geometry of the test stators which is believed to have contributed to the marginal result for weight loss in the phase 2 testing.
• the data from phase 1 shows this material to be appropriate for use as a stator (e.g., seal 30).
• hexagonal boron nitride appears to also to be a suitable replacement for carbon graphite for seals (e.g., seal 30) in high temperature applications.
• a seal or stator could be completely made of a binder embedded with a solid lubricant, such as hexagonal boron nitride.
• the materials included in a stator of a hydrodynamic seal should allow the maintenance of an appropriate operating gap (e.g., up to 0.0002 in.) at an operating temperature of up to 1200 degrees Fahrenheit (F) (e.g., of a high
• stator material is used on the rotor and the material from the rotor could be used on the stator.
• a sliding element 100 e.g., a piston of an engine
• a sealing portion 110 e.g., an inner cylinder wall of an engine
• these elements may be utilized in extreme temperature environments such that the sliding and/or sealing element may be formed of the materials described above and may have a wear rate and surface roughness sufficient to maintain an operating gap between the sliding element and sealing element of about 0.0002 inches.
• the sliding element may be formed of, or may be coated with, CrC-NiCr while the sealing element may include Boronized Inconel 718, hexagonal boron nitride or NASA PS304 coated Inconel 718, for example.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Sealing (AREA)
• Sealing Devices (AREA)
• Sealing Using Fluids, Sealing Without Contact, And Removal Of Oil (AREA)

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  • 2012-08-22 WO PCT/US2012/051783 patent/WO2013062668A1/en active Application Filing
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  • 2012-08-22 CN CN201280052956.5A patent/CN103890320A/zh active Pending
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