Preparation method of high-temperature static strain gauge and high-temperature static strain gauge

Abstract

The invention provides a high-temperature static strain gauge preparation method and a high-temperature static strain gauge, and the high-temperature static strain gauge preparation method comprises the steps: S01, carrying out the surface treatment of a test piece; s02, pasting a working strain gauge on the surface of the test piece; s03, laying a first high-temperature cotton insulating layer above the working strain gauge; s04, laying a compensation strain unit on the first high-temperature cotton insulating layer; s05, laying a second high-temperature cotton insulating layer on the compensation strain unit; and S06, bridging is carried out, and the second high-temperature cotton insulating layer is covered with a protective layer. According to the invention, the problem of large difference between steady-state thermal output and transient thermal output caused by a curve correction method is solved, and real-time measurement of static strain in a high-temperature environment is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-temperature static strain testing, and particularly relates to a high-temperature static strain gauge preparation method and a high-temperature static strain gauge. BACKGROUND

[0002] The existing high-temperature static strain measurement method with a compensation strain gauge solves the problem of the same temperature field of the compensation strain gauge and the working strain gauge, but cannot guarantee the flatness of the installation surface of the compensation strain gauge, and the installation method of spraying and fixing between the compensation strain gauge and the working strain gauge causes the grid wire of the compensation strain gauge to still deform with the deformation of the working strain gauge, resulting in the problem of stress of the compensation strain gauge, which cannot meet the condition that the compensation strain gauge only senses temperature and does not sense stress. Therefore, a new type of high-temperature static strain gauge with a compensation strain gauge in a high-temperature environment is needed. SUMMARY

[0003] Therefore, the present application provides a high-temperature static strain gauge preparation method and a high-temperature static strain gauge to solve the problem that the existing domestic high-temperature static strain testing cannot completely make the compensation strain gauge not stressed, and improve the accuracy and reliability of high-temperature static strain measurement results.

[0004] The present application provides the following technical solutions: 1. A high-temperature static strain gauge preparation method, comprising: step S01, surface treatment of a test piece; step S02, pasting a working strain gauge on the surface of the test piece; step S03, laying a first high-temperature cotton insulation layer above the working strain gauge; step S04, laying a compensation strain unit on the first high-temperature cotton insulation layer; step S05, laying a second high-temperature cotton insulation layer on the compensation strain unit; and step S06, bridge assembly and covering a protective layer on the second high-temperature cotton insulation layer.

[0005] A high-temperature static strain gauge, comprising: a working strain gauge pasted on a test piece; a first high-temperature cotton insulation layer laid on the upper surface of the working strain gauge; a compensation strain unit laid on the upper surface of the first high-temperature cotton insulation layer; a second high-temperature cotton insulation layer laid on the upper surface of the compensation strain unit; and a protective layer covering the second high-temperature cotton insulation layer.

[0006] Compared with the prior art, the above-mentioned at least one technical solution adopted by the present application can achieve at least the following beneficial effects: The compensation strain gauge and the working strain gauge are measured in the same temperature field, the problem of large difference between the steady-state thermal output and the transient thermal output caused by the curve correction method is solved, and real-time static strain measurement in a high-temperature environment is realized.

[0007] This invention breaks through the limitations of traditional strain gauge bonding. The novel strain gauge bonding method ensures that the strain gauge is only subjected to material strain caused by temperature. Because the strain gauge is wrapped in high-temperature cotton, the problem of strain gauge bonding stress is solved. Unevenness in the bonding position will not cause unevenness on the strain gauge surface, reducing the risk of strain gauge damage due to stress. Attached Figure Description

[0008] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 A schematic diagram of the process for manufacturing a high-temperature static strain gauge with a novel compensation strain gauge for this invention.

[0010] Figure 2 This is a three-dimensional schematic diagram of the layered structure of a high-temperature static strain gauge with a novel compensation strain gauge, which was fabricated according to the present invention.

[0011] Figure 3 This is a two-dimensional structural schematic diagram of a high-temperature static strain gauge with a novel compensation strain gauge, which was fabricated according to the present invention.

[0012] The figures are labeled as follows: 1. Test piece; 2. Working strain gauge; 3. First high-temperature cotton insulation layer; 4. Compensating strain gauge; 5. Metal sheet; 6. Second high-temperature cotton insulation layer; 7. Protective layer. Detailed Implementation

[0013] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0014] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0015] like Figure 1 As shown, this embodiment of the invention provides a method for preparing a high-temperature static strain gauge, including the following steps: Step S01: Select the test piece surface treatment material as high-temperature alloy (such as Inconel718), which will be used for static strain test in 800℃ high-temperature environment. First, use acetone as a chemical cleaning agent to wipe the test piece area to be pasted with working strain gauge, remove surface dust, oil stains and other impurities; then use 1200 mesh water sandpaper to finely polish the area, remove the surface oxide layer, and control the surface roughness Ra between 0.8-1.2μm after polishing, ensure the flatness of the strain gauge pasting position, and ensure the insulation performance after subsequent pasting. After polishing, wipe it clean with acetone again and dry naturally for standby.

[0016] Step S02: Paste working strain gauge Use special flame spraying equipment to paste high-temperature working strain gauge (select HFN series strain gauge, working temperature up to 870℃) on the specified measurement position of the test piece after surface treatment. During the flame spraying process, control the spraying flame temperature to 1200℃, the spraying distance to 150mm, and the spraying pressure to 0.6MPa, to ensure that the working strain gauge is tightly attached to the surface of the test piece, firmly pasted, and free of bubbles and edge lifting.

[0017] Step S03: Lay the first high-temperature cotton insulation layer Select alumina fiber cotton as the material of the first high-temperature cotton insulation layer, which can withstand a temperature of up to 1200℃ and maintain stable heat insulation and insulation performance in high-temperature environments. According to the size of the working strain gauge, cut the appropriate size of alumina fiber cotton and lay it flat on the upper surface of the working strain gauge with a thickness of 1mm, ensuring complete coverage of the working strain gauge and insulation isolation between the working strain gauge and the subsequent structure.

[0018] Step S04: Lay the compensation strain unit First, select a high-temperature alloy sheet of the same material as the test piece, with a thickness of 0.12mm, and cut it into a shape matching the size of the working strain gauge. Paste the compensation strain gauge of the same model as the working strain gauge on the center of the metal sheet using high-temperature adhesive, ensuring that the compensation strain gauge is flat and free of wrinkles and shifts during the pasting process, forming a compensation strain unit. After the adhesive solidifies, place the compensation strain unit on the upper surface of the first high-temperature cotton insulation layer, aligning the compensation strain gauge with the working strain gauge in the vertical direction, ensuring that both are in the same temperature field.

[0019] Step S05: Lay the second high-temperature cotton insulation layer Use the same alumina fiber cotton as the first high-temperature cotton insulation layer, cut it and lay it flat on the upper surface of the compensation strain unit to form the second high-temperature cotton insulation layer, with a thickness of 1mm. At this time, the compensation strain unit is completely wrapped by the first and second high-temperature cotton insulation layers and is not in direct contact with the test piece, avoiding being affected by the force generated by the deformation of the test piece and only sensing temperature changes.

[0020] Step S06: Bridge and cover the protective layer First, connect the lead wires of the working strain gauge and the lead wires of the compensation strain gauge according to the half-bridge connection method to form a half-bridge measurement circuit. Through the circuit, the strain value caused by temperature change can be effectively offset, and only the static strain caused by force change is measured. Subsequently, a high-temperature-resistant stainless steel protective layer is selected and covered on the upper surface of the second high-temperature cotton insulation layer, and the entire strain gauge structure is completely wrapped. A lead wire hole is reserved on the protective layer, and the measurement lead wire connected between the working strain gauge and the compensation strain gauge is led out from the reserved hole, which is convenient for subsequent connection with the measurement equipment. Finally, the protective layer is fixed on the test piece by high-temperature bolts to ensure the stability of the entire structure in the high-temperature environment.

[0021] Variant Embodiment 1 The core difference between this variant embodiment and the basic embodiment is the adjustment of the test piece material, the high-temperature cotton insulation layer material and thickness, which is suitable for static strain testing in a 600℃ medium-high temperature environment, as follows: Step S01: Surface treatment of test piece The test piece material is selected as 304 stainless steel, and the surface treatment method of the bonding area is consistent with that of the basic embodiment. The final control of the surface roughness Ra is between 0.6-1.0μm, which ensures the flatness and insulation.

[0022] Step S02: Paste working strain gauge A flame spraying device is used, and a HFN series high-temperature strain gauge (working temperature up to 870℃) is selected. The spraying flame temperature is controlled at 1000℃, the spraying distance is 120mm, and the spraying pressure is 0.5MPa, to ensure firm bonding of the working strain gauge.

[0023] Step S03: Laying Select aluminum silicate fiber cotton (high-temperature resistant temperature 1000℃), and adjust the laying thickness to 3mm. Other laying requirements are consistent with those of the basic embodiment.

[0024] Step S04: Laying compensation strain unit metal sheet Select the same material as the 304 stainless steel test piece, with a thickness of 0.3mm. The compensation strain gauge and the working strain gauge are of the same type, and the bonding and placement methods are the same as those of the basic embodiment.

[0025] Step S05: Laying the second high-temperature cotton insulation layer Select aluminum silicate fiber cotton again, and lay it to a thickness of 3mm to ensure that it wraps the compensation strain unit.

[0026] Step S06: Bridge and cover the protective layer The bridge connection method is consistent with that of the basic embodiment. The protective layer is made of 304 stainless steel, and is fixed by welding. The size of the reserved lead wire hole is adjusted according to the number of lead wires, and other requirements remain unchanged.

[0027] Variant Embodiment 2 The present embodiment is aimed at the static strain test requirement in high temperature environment above 1000℃, and the preparation method and structure are optimized, and the specific embodiments are as follows: Step S01: surface treatment of test piece The test piece is selected from silicon carbide ceramic matrix composite, the surface of the test piece is cleaned by using a plasma cleaning machine, impurities and oxide layers are removed, then the surface is polished by using a diamond grinding wheel, the surface roughness Ra is controlled to be between 1.0-1.5 μm, and the surface is cleaned again by using the plasma cleaning machine to ensure the cleanliness and flatness of the surface.

[0028] Step S02: paste working strain gauge The working strain gauge is pasted by using a GC high-temperature ceramic adhesive instead of a flame spraying method, the working strain gauge is selected from an HFH series strain gauge (working temperature up to 1375℃), the adhesive is applied to a thickness of 0.4 mm, and the working strain gauge is cured in a 315℃ oven for 2 hours to ensure firm adhesion.

[0029] Step S03: lay the first high-temperature cotton insulation layer Zirconia fiber cotton (high-temperature resistance temperature 1600℃) is selected, and the laying thickness is 1 mm. High-temperature refractory glue is used for spot fixing during the laying process to prevent displacement.

[0030] Step S04: lay the compensation strain unit metal sheet The high-temperature alloy sheet (such as GH4169) matched with the thermal expansion coefficient of the silicon carbide ceramic matrix composite is selected, and the thickness is 0.12 mm. The compensation strain gauge and the working strain gauge are of the same type, and are pasted on the metal sheet by using a high-temperature ceramic adhesive. After curing, the compensation strain gauge is placed on the first high-temperature cotton insulation layer to ensure alignment with the working strain gauge.

[0031] Step S05: lay the second high-temperature cotton insulation layer Zirconia fiber cotton is selected, and the laying thickness is 1 mm. High-temperature refractory glue is also used for spot fixing to completely wrap the compensation strain unit.

[0032] Step S06: bridge and cover the protective layer The bridge method is a half-bridge method, and the protective layer is selected from high-temperature alloy steel plate (material Inconel625). The high-temperature steel plate is fixed on the test piece by using high-temperature bolts, the lead hole is insulated and protected by using high-temperature ceramic sleeve, and the lead is selected from high-temperature armored cable to ensure normal work in high-temperature environment.

[0033] For example, Figure 2 and Figure 3As shown, the application also provides a high-temperature static strain gauge, and the high-temperature static strain gauge obtained by the preparation method, the structure of which comprises a test piece 1, a working strain gauge 2, a first high-temperature cotton insulation layer 3, a compensation strain unit, a second high-temperature cotton insulation layer 6 and a protective layer 7. The working strain gauge 2 is pasted at a designated measurement position of the test piece 1; the first high-temperature cotton insulation layer 3 is laid on the upper surface of the working strain gauge 2; the compensation strain unit is composed of a compensation strain gauge 4 and a metal sheet 5 which are pasted together, and the metal sheet 5 is made of the same material as the test piece 1, and the compensation strain unit is laid on the upper surface of the first high-temperature cotton insulation layer 3; the second high-temperature cotton insulation layer 6 is laid on the upper surface of the compensation strain unit; and the protective layer 7 covers the second high-temperature cotton insulation layer, and the protective layer is provided with a reserved hole for leading out a lead wire.

[0034] In one embodiment, the materials of the first high-temperature cotton insulation layer 3 and the second high-temperature cotton insulation layer 6 are replaced by aluminum silicate fiber cotton, the thickness is adjusted to 1 mm, the material of the metal sheet 5 is matched with the 304 stainless steel test piece 1, and it is suitable for strain measurement in a medium-high temperature environment.

[0035] In another embodiment, the strain gauge is pasted by using a high-temperature ceramic adhesive; the first high-temperature cotton insulation layer 3 and the second high-temperature cotton insulation layer 6 are selected from zirconium oxide fiber cotton with a thickness of 1 mm; the metal sheet 5 is selected from a high-temperature alloy with a thermal expansion coefficient matched with the test piece 1; the protective layer 7 is selected from a higher temperature-resistant alloy steel plate, the lead wire and the lead wire hole are designed with high-temperature protection, and it is suitable for accurate measurement of static strain in a high-temperature environment above 1000℃.

[0036] The high-temperature static strain gauges prepared in the above embodiments ensure that the compensation strain gauge only senses the temperature field and is not affected by the deformation force of the test piece by pasting the compensation strain gauge on the metal sheet with the same material as the test piece or with a matched thermal expansion coefficient, and isolating the compensation strain unit from the working strain gauge and the test piece by using two layers of high-temperature cotton insulation layers. At the same time, the working strain gauge and the compensation strain gauge form a half-bridge circuit, effectively offsetting the strain interference caused by temperature, and realizing real-time and accurate measurement of static strain caused by force change in a high-temperature environment.

[0037] Among them, the basic embodiment is suitable for a high-temperature environment of about 800℃, and the measurement error is ≤±0.5%; the deformation embodiment 1 is suitable for a medium-high temperature environment of about 600℃, and the measurement error is ≤±0.6%; the deformation embodiment 2 is suitable for a super-high temperature environment above 1000℃, and the measurement error is ≤±0.8%, which solves the problem of low measurement accuracy caused by force on the compensation strain gauge in traditional high-temperature static strain measurement, and improves the reliability and stability of the measurement results.

[0038] The above merely describes specific embodiments of the present application and cannot be used to limit the scope of the application, so replacement of equivalent components or equivalent changes and modifications made within the scope of the patent protection of the present application should still fall within the scope of the present patent. In addition, the technical features in the present application can be freely combined with each other, and the technical features can be freely combined with each other.

Claims

1. A method for preparing a high-temperature static strain gauge, characterized in that, include: Step S01: Perform surface treatment on the test piece; Step S02: Attach the working strain gauge to the surface of the test piece; Step S03: Lay the first high-temperature cotton insulation layer above the working strain gauge; Step S04: Lay a strain compensation unit on the first high-temperature cotton insulation layer; Step S05: Lay a second high-temperature cotton insulation layer on the compensation strain unit; Step S06: Perform bridge assembly and cover the protective layer onto the second high-temperature cotton insulation layer.

2. The method for preparing a high-temperature static strain gauge according to claim 1, characterized in that, The specific steps of step S01 are as follows: removing impurities from the surface of the test piece at the bonding location and adjusting its flatness.

3. The method for preparing a high-temperature static strain gauge according to claim 2, characterized in that, Step S02 specifically involves attaching the working strain gauge to the surface of the location to be attached using a flame spraying method.

4. The method for preparing a high-temperature static strain gauge according to claim 3, characterized in that, Step S04 specifically involves: The compensating strain gauge is attached to a metal sheet of the same material as the test piece to form a compensating strain unit; The compensation strain unit is placed on the first high-temperature cotton insulation layer.

5. The method for preparing a high-temperature static strain gauge according to claim 4, characterized in that, Step S06 includes: The leads of the working strain gauge and the compensation strain gauge are combined to form a half-bridge to counteract the strain value caused by temperature.

6. The method for preparing a high-temperature static strain gauge according to claim 5, characterized in that, Step S06 further includes: Cover the entire second high-temperature cotton insulation layer with a protective layer, and lead out the working strain gauge and the compensation strain gauge leads from the reserved holes in the protective layer.

7. The method for preparing a high-temperature static strain gauge according to claim 6, characterized in that, Both the first and second high-temperature cotton insulation layers are made of alumina fiber cotton.

8. A high-temperature static strain gauge, characterized in that, include: Working strain gauge (2) is attached to test piece (1); The first high-temperature cotton insulation layer (3) is laid on the upper surface of the working strain gauge (2); The strain compensation unit is laid on the upper surface of the first high-temperature cotton insulation layer (3); The second high-temperature cotton insulation layer (6) is laid on the upper surface of the compensation strain unit; A protective layer (7) is placed over the second high-temperature cotton insulation layer (6).

9. A high-temperature static strain gauge according to claim 8, characterized in that, The compensation strain unit includes a compensation strain gauge (4) bonded together as a whole and a metal sheet (5).

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