CN110470555B - Non-vacuum atmosphere type refrigerating system of low-temperature micro-nano indentation testing system - Google Patents
Non-vacuum atmosphere type refrigerating system of low-temperature micro-nano indentation testing system Download PDFInfo
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- CN110470555B CN110470555B CN201910789670.9A CN201910789670A CN110470555B CN 110470555 B CN110470555 B CN 110470555B CN 201910789670 A CN201910789670 A CN 201910789670A CN 110470555 B CN110470555 B CN 110470555B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D3/00—Devices using other cold materials; Devices using cold-storage bodies
- F25D3/10—Devices using other cold materials; Devices using cold-storage bodies using liquefied gases, e.g. liquid air
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/40—Investigating hardness or rebound hardness
- G01N3/54—Performing tests at high or low temperatures
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0014—Type of force applied
- G01N2203/0016—Tensile or compressive
- G01N2203/0019—Compressive
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0058—Kind of property studied
- G01N2203/0076—Hardness, compressibility or resistance to crushing
- G01N2203/0078—Hardness, compressibility or resistance to crushing using indentation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/022—Environment of the test
- G01N2203/0222—Temperature
- G01N2203/0226—High temperature; Heating means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/022—Environment of the test
- G01N2203/0222—Temperature
- G01N2203/0228—Low temperature; Cooling means
Abstract
The invention relates to a non-vacuum atmosphere type refrigerating system of a low-temperature micro-nano indentation testing system, and belongs to the technical field of refrigeration. The system comprises a refrigeration steam generation unit, a vacuum/atmosphere chamber unit, a low-temperature atmosphere refrigeration chamber unit, an indentation depth online tracing unit and a micro-nano indentation loading and detecting unit. The invention is based on a low-temperature atmosphere refrigerating chamber unit, and combines a refrigerating steam generating unit and a vacuum/atmosphere chamber unit to realize the construction of a non-vacuum atmosphere refrigerating environment, so that a sample and a pressure head are simultaneously refrigerated in such a way, and the influence of 'temperature drift' on the indentation testing precision is weakened. Meanwhile, the online tracing unit of the indentation depth can be compatible, the online tracing unit is used for realizing the precise measurement of the indentation depth in the low-temperature environment and the functional expansion of the online tracing calibration and the like of the micro-nano indentation loading and detection unit indentation depth sensor, and a stable low-temperature loading environment is provided for developing and researching a low-temperature micro-nano indentation testing system.
Description
Technical Field
The invention relates to the technical field of refrigeration, in particular to a non-vacuum atmosphere type refrigeration system of a low-temperature micro-nano indentation testing system.
Background
With the development of the national science and technology, the research and development of the performance of the novel material become one of the hotspots in the academic world, and in view of the fact that the traditional material testing means can only obtain the mechanical property of the material under the macro scale, and meanwhile, the dimension of the novel material is gradually transited from the traditional block to the low-dimensional material facing to various extreme service working conditions, such as the nano film material, and the like, it is obvious that the traditional material testing means and the instrument severely restrict the development and development of the novel material.
The research considering the mechanical properties of key service materials such as aerospace engines, polar region and deep sea scientific research equipment, superconducting transmission equipment and the like is widely concerned by academic and engineering circles at home and abroad. The micro-nano indentation testing system is mainly characterized in that micro-area testing is carried out on advanced materials at room temperature through a traditional micro-nano indentation testing instrument, the micro-area testing is different from the actual material service working condition, a material constitutive equation based on the influence of force-heat composite factors cannot be established directly through test data, however, micro-nano indentation testing systems for researching the mechanical property of the materials in a low-temperature environment and the change rule of the mechanical property of the materials along with the temperature are not many, the low-temperature micro-nano indentation testing system independently researched and developed by a research institution generally has large low-temperature 'temperature drift', the phenomenon of 'temperature drift' along with the reduction of the temperature is more obvious, the heat shrinkage of the materials seriously influences the accuracy of a testing result, and the micro-nano indentation testing system does not have the online traceability function of the indentation depth in the low-temperature environment.
Considering that the design of the core refrigeration mode of the low-temperature micro-nano indentation testing system determines the testing function of the instrument, in order to avoid the influence of the icing phenomenon of the surface of the sample in the pressing-in process on the testing curve, the common solution is to combine the vacuum technology and the inert gas protection mode. Although the low-temperature technology related to the test instrument for researching the physical properties of materials is mature, the test instrument can be divided into liquid vaporization refrigeration, adiabatic gas generation refrigeration, gas expansion refrigeration, magnetic refrigeration, thermoelectric refrigeration, vortex tube refrigeration and the like according to different implementation principles, a low-temperature micro-nano indentation test instrument independently researched and developed by research institutions is usually formed by modifying commercial low-temperature equipment such as a cryostat, a liquid nitrogen dewar and the like, the temperature drift phenomenon is mainly caused by the temperature difference between a pressure head and a sample, sensors for detecting the pressing-in depth and the pressing-in load in real time are seriously influenced by the temperature, and a plurality of factors such as a driver, the sensors, the refrigeration efficiency, the refrigerant consumption and the like restrict the test precision of the instrument.
Therefore, the refrigeration system which can realize continuous temperature change and low temperature drift and can be compatible with the functions of pressing depth online tracing and the like in a low-temperature environment is designed and researched, and the development prospect and application value of the low-temperature micro-nano indentation testing instrument in the fields of material science, aerospace, superconducting application and the like are great.
Disclosure of Invention
The invention aims to provide a non-vacuum atmosphere type refrigerating system of a low-temperature micro-nano indentation testing system, which solves the problems in the prior art. The invention can simultaneously realize continuous temperature change and low temperature drift, can be compatible with the functions of online tracing of the pressing depth in a low-temperature environment and the like, and forms a stable low-temperature test environment. The invention is based on a low-temperature atmosphere refrigerating chamber unit, and combines a refrigerating steam generating unit and a vacuum/atmosphere chamber unit to realize the construction of a non-vacuum atmosphere refrigerating environment, so that a sample and a pressure head are simultaneously refrigerated in such a way, and the influence of 'temperature drift' on the indentation testing precision is weakened. Meanwhile, the online tracing unit of the indentation depth can be compatible, the online tracing unit is used for realizing the precise measurement of the indentation depth in the low-temperature environment and the functional expansion of the online tracing calibration and the like of the micro-nano indentation loading and detection unit indentation depth sensor, and a stable low-temperature loading environment is provided for developing and researching a low-temperature micro-nano indentation testing system.
The above object of the present invention is achieved by the following technical solutions:
the non-vacuum atmosphere type refrigeration system of the low-temperature micro-nano indentation testing system comprises a refrigeration steam generation unit, a vacuum/atmosphere chamber unit, a low-temperature atmosphere refrigeration chamber unit, an indentation depth online tracing unit and a micro-nano indentation loading and detecting unit 1; the micro-nano indentation loading and detecting unit 1 and the low-temperature atmosphere refrigerating chamber unit are integrally arranged in the vacuum/atmosphere chamber unit, water vapor in the whole space is exhausted through inert gas replacement, and the inert gas atmosphere in the vacuum/atmosphere chamber under certain pressure is ensured; a refrigerating gas continuous temperature control nozzle 38 of the refrigerating steam generation unit pumps refrigerating gas such as super-cooled nitrogen into the low-temperature atmosphere refrigerating chamber unit through a refrigerating gas input interface 33 on the wall of the vacuum/atmosphere chamber unit by using a metal hose 37, so that the inside of the chamber is fully refrigerated; a pressure head at the end part of a pressure rod of the micro-nano indentation loading and detecting unit 1 can be replaced by a standard reflecting aluminum mirror 24 for setting up a reflecting light path of the indentation depth online tracing unit; cables such as a temperature measuring element, a piezoelectric driving platform, a laser probe and the like in the low-temperature atmosphere refrigerating chamber unit are connected with a corresponding controller and an industrial personal computer 30 through a connecting cable 29 via an electric/optical fiber interface 31.
The low-temperature atmosphere refrigeration cavity unit is as follows: the sample is adhered to a sample table 130 with good heat conductivity by using low-temperature varnish and further fixedly connected to a double-layer piezoelectric driving platform 129 for replacement in an XY plane at the pressing-in position; the Z-direction height is compensated through the hollow heat-conducting support column 10 and the heat-conducting support column is fixedly connected to the bottom of the heat sink 17 through the wedge groove mounting structure 11, wherein the liquid nitrogen coil II14 is welded on the inner side of the heat sink 17 at uniform intervals, so that the refrigeration temperature of the heat sink 17 is kept constant, a sample on the sample table 130 is refrigerated through contact heat transfer, and meanwhile, the design requirement of a revolution line of the liquid nitrogen coil II14 is not intersected with the moving space 9 of the double-layer piezoelectric driving platform, so that the generation of motion interference is avoided; the outer side of the heat sink 17 is simultaneously provided with a cold screen 15 which is coiled and welded with a liquid nitrogen coil I13, and the heat sink 17 and the cold screen 15 are fixedly arranged on the low-temperature atmosphere refrigeration cavity 5 through a heat insulation supporting structure 12.
Independent heating resistance wires are embedded in the sample table 130 and the micro-nano indentation loading and detecting unit 1 heat insulation pressure rod, so that continuous temperature change of a sample and a pressure head is realized; directly connecting the temperature measuring element with the sample table 130 and the heat sink 17 through low-temperature varnish or low-temperature heat conducting ester, and measuring the surface temperature of the sample and the temperature uniformity in the whole atmosphere space in real time; the output power of the heating resistance wire is adjusted by combining temperature measurement data feedback, and a PID closed-loop temperature control strategy is adopted, so that the independent controllability of the temperature of the pressure head and the temperature of the sample is realized.
The low-temperature atmosphere refrigerating cavity 5 consists of a low-temperature atmosphere refrigerating cavity substrate supporting structure 8, a hard polyurethane foam heat insulating material 52, a low-temperature atmosphere refrigerating cavity stainless steel outer cover 51, a low-temperature atmosphere refrigerating cavity cover 7 and a sealing ring 16, and heat leakage of refrigerating capacity is reduced by adopting a stacking heat insulation mode to insulate heat and preserve heat; the low-temperature atmosphere refrigeration cavity stainless steel outer cover 51 is fixedly installed on a 32 marble table of a vacuum/atmosphere cavity through flanges, and is provided with a liquid nitrogen coil pipe inlet and outlet interface flange 2, a double-layer piezoelectric driving platform low-temperature vacuum lead interface flange 3, a low-temperature measurement element weak current signal lead interface flange 4 and a laser interferometer probe low-temperature vacuum optical fiber interface flange 6, in view of the optimized layout of the low-temperature atmosphere refrigeration cavity unit in the vacuum/atmosphere cavity unit, the flange interfaces are arranged in a 60-degree single-side mode, and the liquid nitrogen coil pipe inlet and outlet interface flange 2 is provided with a safety valve and an inflow/outflow quick-insertion low-temperature interface of a liquid nitrogen circulation loop.
Hard polyurethane foam heat insulation materials 52 are filled between the low-temperature atmosphere refrigerating cavity substrate supporting structure 8 and the low-temperature atmosphere refrigerating cavity stainless steel outer cover 51, and the low-temperature atmosphere refrigerating cavity cover 7 is connected to the low-temperature atmosphere refrigerating cavity substrate supporting structure 8 through a sealing ring 16.
The section shapes of the liquid nitrogen coil I13 welded to the heat sink 17 and the liquid nitrogen coil II14 welded to the cold shield 15 can be selected to be 'return' shape or hexagon shape, etc. with larger contact area.
The joint of the low-temperature atmosphere refrigerating cavity cover 7 and the heat sink 17 is designed by adopting a long flange structure, the structure of the low-temperature atmosphere refrigerating cavity is similar to that of the low-temperature atmosphere refrigerating cavity 5, the low-temperature atmosphere refrigerating cavity is composed of a lining, hard polyurethane foam and a stainless steel shell, and the leakage amount of refrigerating nitrogen inside the heat sink 17 is reduced through a through hole 18 structure in clearance fit with a compression bar.
The main body structure of the heat insulation supporting structure 12 adopts a glass fiber reinforced plastic supporting sleeve 123 with low heat conductivity and high strength, and is rigidly connected with the wedge groove mounting structure 11, the heat sink 17, the cold shield 15 and the low-temperature atmosphere refrigeration cavity substrate supporting structure 8 through three layers of hard aluminum flanges I121, II125, I126, III127 and II128 in internal and external interference fit; the duralumin flange I121, the duralumin disk I126 and the duralumin disk II128 in the glass fiber reinforced plastic supporting sleeve 123 are mutually contacted through the multi-layer heat insulation cylinder I122 and the multi-layer heat insulation cylinder II124, and meanwhile, the excellent heat insulation effect is guaranteed.
The press-in depth online tracing unit comprises: because the minimum bending radius of the low-temperature vacuum optical fiber 21 of the low-temperature pressing-in depth on-line tracing laser probe is limited, the internal space of the cavity is reduced by considering the factors of refrigeration efficiency, refrigerant consumption, temperature uniformity of space atmosphere and the like; the laser interferometer probe 20 is fixedly connected to the sleeve 19 through a fastening screw 23 and is connected with the probe mounting bracket 22 through a screw thread at the end of the sleeve 19, wherein the probe mounting bracket 22 is directly fixedly connected to the double-layer piezoelectric driving platform 129 at the bottom of the heat sink 17 through a connecting plate 39 and a wedge groove mounting structure 11 through screws.
The refrigeration steam generation unit is as follows: the compressed nitrogen tank 28 provides continuously adjustable pressure to the liquid nitrogen storage tank 27 through a pressure reducing valve 34, and provides sufficient liquid nitrogen for a liquid nitrogen area in the double-layer dewar tank 26 by utilizing an electromagnetic valve 36 connected in series in a liquid nitrogen transmission pipeline 35, and is provided with a safety valve 25 for ensuring constant internal pressure; liquid nitrogen is vaporized through a needle type electromagnetic valve and a heater which are arranged in the double-layer Dewar flask 26 and is stored in a refrigerating nitrogen region, the temperature of the refrigerating nitrogen is ensured to be close to the boiling point temperature by utilizing the liquid nitrogen, and refrigerating steam with continuously adjustable temperature is generated through the refrigerating gas continuous temperature control nozzle 38.
The invention has the beneficial effects that:
1. the invention has simple structure and compact layout, adopts a non-vacuum atmosphere refrigeration mode to refrigerate the sample and the pressure head simultaneously, is used for weakening the influence of 'temperature drift' on the indentation test precision, obtains a precise low-temperature indentation test data result, simultaneously provides steady-state refrigeration nitrogen with continuously adjustable flow and temperature and fast temperature change rate through the refrigeration steam generation unit, and is convenient for researching the change rule of the mechanical property of the advanced material along with the temperature.
2. By adjusting the Z-direction height, the online tracing depth measuring device can be fully compatible with the online tracing depth measuring unit for realizing the accurate measurement of the pressing depth in a low-temperature environment and the functional expansion of the online tracing calibration of the pressing depth sensor of the micro-nano indentation loading and detecting unit and the like.
3. The invention adopts a modular design, is based on a low-temperature atmosphere refrigeration cavity unit, realizes the construction of a non-vacuum atmosphere refrigeration environment by combining a refrigeration steam generation unit and a vacuum/atmosphere cavity unit, provides a steady low-temperature loading environment for the development of a low-temperature micro-nano indentation testing system, is used as a core module of the testing system, and is also beneficial to the combined installation, the improvement and the optimization and the maintenance of the whole machine based on the modular design.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention.
FIG. 1 is an isometric view of the overall arrangement of the present invention;
FIG. 2 is a cross-sectional view of a mechanical structure of an indentation testing process of the present invention;
FIG. 3 is a cross-sectional view of the overall mechanical structure of the present invention;
FIG. 4 is a cross-sectional view of the indentation depth on-line tracing mechanism of the present invention;
FIG. 5 is an enlarged view of a portion of the thermally insulating support structure of the present invention;
FIG. 6 is an exploded view of the assembly structure of the indentation depth on-line tracing unit of the present invention;
fig. 7 is a schematic diagram of the refrigeration system and test wiring of the present invention.
In the figure: 1. a micro-nano indentation loading and detecting unit; 2. a liquid nitrogen coil pipe inlet and outlet interface flange; 3. a double-layer piezoelectric driving platform low-temperature vacuum lead interface flange; 4. a low-temperature measuring element weak current signal lead interface flange; 5. a low-temperature atmosphere refrigeration cavity; 6. a low-temperature vacuum optical fiber interface flange of a laser interferometer probe; 7. a low-temperature atmosphere refrigerating chamber cover; 8. a low temperature atmosphere refrigeration cavity substrate support structure; 9. a double-layer piezoelectric driving platform moving space; 10. a thermally conductive support column; 11. a wedge groove mounting structure; 12. an insulating support structure; 13. a liquid nitrogen coil pipe I; 14. a liquid nitrogen coil pipe II; 15. cooling the screen; 16. a seal ring; 17. a heat sink; 18. a through hole; 19. a sleeve; 20. a laser interferometer probe; 21. a low temperature vacuum optical fiber; 22. a probe mounting bracket; 23. fastening screws; 24. a standard reflective aluminum mirror; 25. a safety valve; 26. a double-layer dewar tank; 27. a liquid nitrogen storage tank; 28. a compressed nitrogen tank; 29. connecting a cable; 30. a controller and an industrial personal computer; 31. an electrical/fiber interface; 32. a vacuum/ambient chamber; 33. a refrigerant gas input interface; 34. a pressure reducing valve; 35. a liquid nitrogen transmission line; 36. an electromagnetic valve; 37. a metal hose; 38. a continuous temperature control nozzle for the refrigerating gas; 39. a connecting plate; 51. a stainless steel outer cover of the low-temperature atmosphere refrigeration cavity; 52. rigid polyurethane foam insulation; 121. a hard aluminum flange I; 122. a multilayer thermally insulating cylinder I; 123. a glass fiber reinforced plastic support sleeve; 124. a multilayer thermally insulating cylinder II; 125. a duralumin flange II; 126. a duralumin disk I; 127. a duralumin flange III; 128. a duralumin disk II; 129. a double-layer piezoelectric driving platform; 130. a sample stage.
Detailed Description
The details of the present invention and its embodiments are further described below with reference to the accompanying drawings.
Referring to fig. 1 to 7, the non-vacuum atmosphere type refrigeration system of the low-temperature micro-nano indentation testing system can solve the problems that continuous temperature change cannot be realized, low-temperature 'temperature drift' influence is large, and functions such as online tracing of indentation depth in a low-temperature environment cannot be compatible in the existing low-temperature indentation technology. The system comprises a refrigeration steam generation unit, a vacuum/atmosphere chamber unit, a low-temperature atmosphere refrigeration chamber unit, an online indentation depth tracing unit and a micro-nano indentation loading and detecting unit 1, wherein the micro-nano indentation loading and detecting unit 1 and the low-temperature atmosphere refrigeration chamber unit are integrally arranged in the vacuum/atmosphere chamber unit, twice inert gases are replaced, water vapor in the whole space is exhausted, and refrigeration gas is introduced into the low-temperature atmosphere refrigeration chamber unit through a refrigeration gas continuous temperature control nozzle 38 of the refrigeration steam generation unit and a refrigeration gas input interface 33 on the wall of the vacuum/atmosphere chamber unit by using a metal hose 37; the micro-nano indentation loading and detecting unit 1 is characterized in that a diamond pressure head at the end part of a replaceable pressure lever is a standard reflecting aluminum mirror 24 for building light path reflection for an indentation depth online tracing unit, wherein the micro-nano indentation loading and detecting unit 1, the double-layer piezoelectric driving platform 129 and the indentation depth online tracing unit are used as main heat load sources of a refrigerating system and are used for realizing testing functions of a low-temperature micro-nano indentation testing system, the indentation depth online tracing and the like; cables such as a temperature measuring element, a piezoelectric driving platform, a laser probe and the like in the low-temperature atmosphere refrigerating chamber unit are connected with a corresponding controller and an industrial personal computer 30 through a connecting cable 29 via an electric/optical fiber interface 31.
The refrigerating steam generating unit comprises a double-layer Dewar tank 26, a liquid nitrogen storage tank 27, a compressed nitrogen tank 28, a pressure reducing valve 34, a liquid nitrogen transmission pipeline 35, an electromagnetic valve 36, a metal hose 37, a refrigerating gas continuous temperature control nozzle 38 and the like, wherein the compressed nitrogen tank 28 provides continuously adjustable pressure for the liquid nitrogen storage tank 27 through the pressure reducing valve 34, the electromagnetic valve 36 connected in series in the liquid nitrogen transmission pipeline 35 is used for providing sufficient liquid nitrogen for a liquid nitrogen area in the double-layer Dewar tank 26, and a safety valve 25 is designed to ensure constant internal pressure; liquid nitrogen is vaporized through a needle type electromagnetic valve and a heater which are arranged in the double-layer Dewar flask 26 and is stored in a refrigerating nitrogen region, the temperature of the refrigerating nitrogen is ensured to be close to the boiling point temperature by utilizing the liquid nitrogen, and refrigerating steam with continuously adjustable temperature is generated through the refrigerating gas continuous temperature control nozzle 38.
The low-temperature atmosphere refrigeration cavity unit comprises a heat sink 17, a cold screen 15, a liquid nitrogen coil I13, a liquid nitrogen coil II14, a low-temperature atmosphere refrigeration cavity 5, a liquid nitrogen coil inlet and outlet interface flange 2, a double-layer piezoelectric driving platform low-temperature vacuum lead interface flange 3, a low-temperature measuring element weak electric signal lead interface flange 4, a laser interferometer probe low-temperature vacuum optical fiber interface flange 6 and the like, wherein a sample is bonded on a sample table 130 with good heat conductivity by using low-temperature varnish and is further fixedly connected to a double-layer piezoelectric driving platform 129 for replacement of a pressed position in an XY plane; the Z-direction height is compensated through the hollow heat-conducting support columns 10 and is fixedly connected to the bottom of the heat sink 17 through the wedge groove mounting structure 11, wherein liquid nitrogen coil pipes II14 are welded on the inner side of the heat sink 17 at uniform intervals to ensure that the refrigeration temperature of the heat sink 17 is kept constant and a sample on the sample table 130 is refrigerated through contact heat transfer, and meanwhile, the design requirement of a revolution line of the liquid nitrogen coil pipes II14 is not intersected with the moving space 9 of the double-layer piezoelectric driving platform, so that the generation of motion interference is avoided; the outer side of the heat sink 17 is simultaneously provided with a cold screen 15 structure which is coiled and welded with a liquid nitrogen coil I13, the heat sink 17 and the cold screen 15 are fixedly installed on the low-temperature atmosphere refrigeration cavity 5 through a heat insulation supporting structure 12, wherein the low-temperature atmosphere refrigeration cavity 5 consists of a low-temperature atmosphere refrigeration cavity substrate supporting structure 8 for supporting internal elements, a hard polyurethane foam heat insulation material 52 for accumulating heat insulation, a low-temperature atmosphere refrigeration cavity stainless steel outer cover 51 with corresponding interfaces, a detachable low-temperature atmosphere refrigeration cavity cover 7 and a sealing ring 16; the low-temperature atmosphere refrigeration cavity stainless steel outer cover 51 is fixedly installed on a 32 marble table of a vacuum/atmosphere cavity through flanges, and is provided with a liquid nitrogen coil pipe inlet and outlet interface flange 2, a double-layer piezoelectric driving platform low-temperature vacuum lead interface flange 3, a low-temperature measurement element weak current signal lead interface flange 4 and a laser interferometer probe low-temperature vacuum optical fiber interface flange 6, in view of the optimized layout of the low-temperature atmosphere refrigeration cavity unit in the vacuum/atmosphere cavity unit, the flange interfaces are arranged at one side of 60 degrees, and the liquid nitrogen coil pipe inlet and outlet interface flange 2 is provided with a safety valve and forms an inflow/outflow quick-plugging low-temperature interface of a liquid nitrogen circulation loop.
The liquid nitrogen coil I13 welded to the heat sink 17 and the liquid nitrogen coil II14 welded to the cold shield 15 may have a cross-sectional coil shape with a larger contact area, such as a square shape, a hexagon shape, etc.
The joint of the low-temperature atmosphere refrigerating cavity cover 7 and the heat sink 17 is designed by adopting a long flange structure, the structure of the low-temperature atmosphere refrigerating cavity cover is similar to that of the low-temperature atmosphere refrigerating cavity 5, the low-temperature atmosphere refrigerating cavity cover is composed of a lining, hard polyurethane foam and a stainless steel shell, and the leakage amount of refrigerating nitrogen inside the heat sink 17 is reduced through a through hole 18 structure in clearance fit with the micro-nano indentation loading and detection unit 1 pressure rod.
The main body structure of the heat insulation supporting structure 12 adopts a glass fiber reinforced plastic supporting sleeve 123 with low heat conductivity and high strength, and is rigidly connected with the wedge groove mounting structure 11, the heat sink 17, the cold screen 15 and the low-temperature atmosphere refrigeration cavity substrate supporting structure 8 through three layers of hard aluminum flanges I121, II125, I126, III127 and II128 in interference fit; the duralumin flange I121, the duralumin disk I126 and the duralumin disk II128 inside the glass fiber reinforced plastic support sleeve 123 are in mutual contact through the multi-layer insulating cylinder I122 and the multi-layer insulating cylinder II124 while ensuring excellent insulation.
The online tracing unit of the press-in depth comprises a laser interferometer probe 20, a low-temperature vacuum optical fiber 21, a fastening screw 23, a sleeve 19, a probe mounting bracket 22 and the like, wherein the press-in depth is limited by the minimum bending radius of the low-temperature vacuum optical fiber 21 of the online tracing laser probe at low temperature, and the factors such as refrigeration efficiency, refrigerant consumption, temperature uniformity of space atmosphere and the like are considered at the same time, so that the internal space of the cavity is reduced; the laser interferometer probe 20 is fixedly connected to the sleeve 19 through a fastening screw 23 and is connected with the probe mounting support 22 through a threaded structure at the end of the sleeve 19, wherein the probe mounting support 22 is fixedly connected to a double-layer piezoelectric driving platform 129 directly fixedly connected to the bottom of the heat sink 17 through a wedge groove mounting structure 11 through a connecting plate 39 through a screw, and the double-layer piezoelectric driving platform is used for aligning and adjusting the light path of the laser probe and tracing the pressed depth at a low temperature on line.
Referring to fig. 1 to 7, the specific test procedure of the present invention is as follows:
before the low-temperature micro-nano indentation test, in order to verify whether the low-temperature drift is eliminated or not, namely whether the precise measurement of the indentation depth is accurate or not, elements such as the sample stage 130, the heat conduction support column 10 and the like are replaced by an indentation depth online tracing unit, meanwhile, a diamond pressure head at the end part of a pressure rod of the micro-nano indentation loading and detecting unit 1 is replaced by a standard reflection aluminum mirror 24, and a single reflection test light path is constructed and used for online tracing of the indentation depth and calibration of the precise displacement sensor in a low-temperature non-vacuum environment.
The first line connections to the refrigeration system, including the refrigeration nitrogen line connections and the drive sensing element electrical connections, are made by twice replacing the air in the vacuum/ambient chamber 32 with an inert gas (e.g., helium) to evacuate the entire volume of water vapor and avoid contaminating the sample surface and the laser interferometer probe 20. Secondly, by controlling the opening and closing of the electromagnetic valve 36 in the liquid nitrogen transmission pipeline 35, continuous and sufficient liquid nitrogen is provided for the double-layer Dewar tank 26 to maintain the long-time low-temperature environment loading, meanwhile, the liquid nitrogen is vaporized into 77K constant-temperature steam by utilizing the heater and the electromagnetic valve in the double-layer Dewar tank 26, a continuous refrigeration gas temperature control nozzle 38 is connected with the liquid nitrogen coil pipe inlet and outlet interface flange 2 through a refrigeration gas input interface 33 on the side wall of the vacuum/atmosphere cavity 32, and continuous and stable refrigeration nitrogen is introduced into the heat sink 17 cavity in the low-temperature atmosphere refrigeration cavity 5. The voltage of a heater in the double-layer Dewar tank 26 is controlled in a closed loop mode through a silicon diode temperature measuring element adhered by low-temperature heat-conducting ester in the heat sink 17, and the input flow of refrigeration nitrogen is changed, namely, the cooling rate is indirectly regulated and controlled. And finally, when the reading of the temperature measuring element is stable, the input voltage of the heater is reduced, the flow of the refrigerating nitrogen introduced into the low-temperature atmosphere refrigerating cavity 5 is reduced, and the load change caused by fluid disturbance and the space refractive index between the laser interferometer probe 20 and the standard reflecting aluminum mirror 24 are reduced, so that a stable low-temperature loading environment is constructed.
In the process of online tracing testing of the indentation depth in the low-temperature environment, the relative position relationship between the probe 20 of the laser interferometer and the standard reflecting aluminum mirror 24 is adjusted through the double-layer piezoelectric driving platform 129, the movement of the standard reflecting aluminum mirror 24 in the Z direction is realized by utilizing the driver of the micro-nano indentation loading and detecting unit 1, and the online tracing calibration is carried out on the indentation depth measuring sensor when the standard reflecting aluminum mirror enters the detection range of the laser interferometer.
After the indentation depth online tracing test process is finished, the voltage of the heater in the double-layer dewar tank 26 is temporarily adjusted to be minimum, but the continuous weak flow of the refrigeration nitrogen gas flowing out from the refrigeration gas continuous temperature control nozzle 38 is ensured, so that the test time is prevented from being increased by repeated precooling of the refrigeration steam generation unit in the indentation test process. The low-temperature atmosphere refrigeration cavity 5 needs to be restored to the room temperature, the vacuum/atmosphere cavity 32 can be opened, the online indentation depth tracing unit is replaced by the heat conduction support column 10, the sample table 130 and other elements, the temperature reduction process is repeated, however, the stop valve on the double-layer dewar tank 26 needs to be manually closed during inert gas replacement, and the cavity is refrigerated again after the gas replacement in the vacuum/atmosphere cavity 32 is finished.
In the indentation test process, the compression bar and the diamond pressure head of the micro-nano indentation loading and detecting unit 1 pass through the through hole 18 in the low-temperature atmosphere refrigerating cavity cover 7, the pressing position is replaced in the low-temperature environment by using the double-layer piezoelectric driving platform 129, and the micro-nano indentation test of samples with different sizes in the low-temperature environment is completed. After the test process is finished, the input voltages of the heater at the refrigerating gas continuous temperature control nozzle 38 and the heater in the double-layer dewar tank 26 are adjusted, nitrogen gas higher than the room temperature is obtained to realize the rapid temperature rise of the low-temperature atmosphere refrigerating cavity 5, and when the temperature is recovered to the room temperature, the pressure relief valve on the vacuum/atmosphere cavity 32 is opened to take out the sample.
The above description is only a preferred example of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like of the present invention shall be included in the protection scope of the present invention.
Claims (7)
1. The utility model provides a little nano indentation test system's of low temperature non-vacuum atmosphere formula refrigerating system which characterized in that: the system comprises a refrigeration steam generation unit, a vacuum/atmosphere chamber unit, a low-temperature atmosphere refrigeration chamber unit, an indentation depth online tracing unit and a micro-nano indentation loading and detecting unit (1); the micro-nano indentation loading and detecting unit (1) and the low-temperature atmosphere refrigerating chamber unit are integrally arranged in the vacuum/atmosphere chamber unit, water vapor in the whole space is exhausted through inert gas replacement, and the inert gas atmosphere in the vacuum/atmosphere chamber is ensured; a refrigerating gas continuous temperature control nozzle (38) of the refrigerating steam generation unit pumps refrigerating gas into the low-temperature atmosphere refrigerating chamber unit through a refrigerating gas input interface (33) on the wall of the vacuum/atmosphere chamber unit by using a metal hose (37) to realize refrigeration; the temperature measuring element, the piezoelectric driving platform and the laser probe cable in the low-temperature atmosphere refrigerating chamber unit are connected with a controller and an industrial personal computer (30) through a connecting cable (29) by an electric/optical fiber interface (31);
the low-temperature atmosphere refrigeration cavity unit is as follows: a sample is adhered to the sample table (130) by using low-temperature varnish and further fixedly connected to the double-layer piezoelectric driving platform (129); the Z-direction height is compensated through a hollow heat conduction support column (10) and the heat conduction support column is fixedly connected to the bottom of a heat sink (17) through a wedge groove mounting structure (11), wherein liquid nitrogen coil pipes II (14) are welded on the inner side of the heat sink (17) at uniform intervals, so that the refrigeration temperature of the heat sink (17) is kept constant, a sample on a sample table (130) is refrigerated through contact heat transfer, and meanwhile, a rotation line of the liquid nitrogen coil pipe II (14) does not intersect with a moving space (9) of a double-layer piezoelectric driving platform, and the generation of motion interference is avoided; the outer side of the heat sink (17) is simultaneously provided with a cold screen (15) which is coiled and welded with a liquid nitrogen coil I (13), and the heat sink (17) and the cold screen (15) are installed and fixed on the low-temperature atmosphere refrigeration cavity (5) through a heat insulation supporting structure (12).
2. The non-vacuum atmosphere type refrigeration system of the low-temperature micro-nano indentation testing system according to claim 1, characterized in that: the low-temperature atmosphere refrigerating cavity (5) consists of a low-temperature atmosphere refrigerating cavity substrate supporting structure (8), a hard polyurethane foam heat insulating material (52), a low-temperature atmosphere refrigerating cavity stainless steel outer cover (51), a low-temperature atmosphere refrigerating cavity cover (7) and a sealing ring (16), and heat leakage of refrigerating capacity is reduced by adopting a stacking heat insulation mode to insulate heat and preserve heat; a stainless steel outer cover (51) of a low-temperature atmosphere refrigeration cavity is fixedly installed on a marble table of a vacuum/atmosphere cavity (32) through a flange, a liquid nitrogen coil pipe in-and-out interface flange (2), a double-layer piezoelectric driving platform low-temperature vacuum lead interface flange (3), a low-temperature measuring element weak current signal lead interface flange (4) and a laser interferometer probe low-temperature vacuum optical fiber interface flange (6) are designed, and a safety valve and an inflow/outflow quick-insertion low-temperature interface of a liquid nitrogen circulation loop are designed on the liquid nitrogen coil pipe in-and-out interface flange (2).
3. The non-vacuum atmosphere type refrigeration system of the low-temperature micro-nano indentation testing system according to claim 1, characterized in that: the section shapes of the liquid nitrogen coil I (13) and the liquid nitrogen coil II (14) are in a shape like a Chinese character 'hui' or a hexagon.
4. The non-vacuum atmosphere type refrigeration system of the low-temperature micro-nano indentation testing system according to claim 2, characterized in that: the joint of the low-temperature atmosphere refrigerating cavity cover (7) and the heat sink (17) adopts a long flange structure design, and the leakage amount of refrigerating nitrogen inside the heat sink (17) is reduced through a through hole (18) structure in clearance fit with the pressure rod.
5. The non-vacuum atmosphere type refrigeration system of the low-temperature micro-nano indentation testing system according to claim 1, characterized in that: the main body structure of the heat insulation supporting structure (12) adopts a glass fiber reinforced plastic supporting sleeve (123) and is rigidly connected with a wedge groove mounting structure (11), a heat sink (17), a cold shield (15) and a low-temperature atmosphere refrigeration cavity substrate supporting structure (8) through three layers of hard aluminum flanges I (121), hard aluminum flanges II (125), hard aluminum discs I (126), hard aluminum flanges III (127) and hard aluminum discs II (128) which are in interference fit; the duralumin flange I (121), the duralumin disk I (126) and the duralumin disk II (128) in the glass fiber reinforced plastic supporting sleeve (123) are mutually contacted through the multilayer heat insulation cylinder I (122) and the multilayer heat insulation cylinder II (124) and ensure excellent heat insulation effect;
divide into the three-layer from top to bottom along the axis direction of glass steel support sleeve (123), the first layer is duralumin flange I (121), and the second floor is duralumin disc II (128) and duralumin flange III (127), and the third layer is duralumin flange II (125) and duralumin disc I (126), duralumin flange I (121), duralumin flange II (125) and duralumin flange III (127) all with glass steel support sleeve (123) interior interference fit, duralumin disc I (126) and duralumin disc II (128) all with glass steel support sleeve (123) outer interference fit.
6. The non-vacuum atmosphere type refrigeration system of the low-temperature micro-nano indentation testing system according to claim 1, characterized in that: the press-in depth online tracing unit comprises: the laser interferometer probe (20) is fixedly connected to the sleeve (19) through a fastening screw (23) and is connected with the probe mounting bracket (22) through threads at the end part of the sleeve (19), wherein the probe mounting bracket (22) is fixedly connected to a double-layer piezoelectric driving platform (129) at the bottom of the heat sink (17) through a wedge groove mounting structure (11) through a connecting plate (39).
7. The non-vacuum atmosphere type refrigeration system of the low-temperature micro-nano indentation testing system according to claim 1, characterized in that: the refrigeration steam generation unit is as follows: the compressed nitrogen tank (28) provides continuously adjustable pressure for the liquid nitrogen storage tank (27) through a pressure reducing valve (34), an electromagnetic valve (36) connected in series in a liquid nitrogen transmission pipeline (35) is used for providing sufficient liquid nitrogen for a liquid nitrogen area in the double-layer Dewar tank (26), and a safety valve (25) is designed to ensure constant internal pressure; liquid nitrogen is vaporized and stored in a refrigerating nitrogen region through a needle type electromagnetic valve and a heater which are arranged in a double-layer Dewar tank (26), the temperature of the refrigerating nitrogen is ensured to be close to the boiling point temperature by utilizing the liquid nitrogen, and refrigerating steam with continuously adjustable temperature is generated through a refrigerating gas continuous temperature control nozzle (38).
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| CN117030430B (en) * | 2023-08-04 | 2024-02-06 | 青岛海洋地质研究所 | Hydrate nanometer indentation device |
| CN117030429B (en) * | 2023-08-04 | 2024-03-19 | 青岛海洋地质研究所 | Temperature control device and method for nano probe pressure head suitable for hydrate surface test |
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| CN104697872B (en) * | 2015-01-12 | 2017-06-13 | 吉林大学 | The micro-nano mark test method of continuous regulating temperature type high vacuum low temperature and device |
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