Double-diaphragm sputtering film core and application thereof

Abstract

The invention discloses a double-diaphragm sputtering film core body and application, and relates to the technical field of sensor core bodies, the double-diaphragm sputtering film core body comprises a pressure sensing diaphragm and a Wheatstone bridge diaphragm, the pressure sensing diaphragm and the Wheatstone bridge diaphragm are connected through a force conduction rod, a protection layer is arranged in the Wheatstone bridge diaphragm, and the pressure sensing diaphragm and the Wheatstone bridge diaphragm are connected through a force conduction rod. The protective layer sequentially comprises a transition bottom layer, a protective middle layer and a closed outer layer from bottom to top; the protective intermediate layer is prepared from the following preparation raw materials in percentage by mass: 10-25% of nano aluminum oxide, 3-9% of nano zirconium oxide, 0.5-3.0% of boron nitride nanotubes and the balance of nano silicon dioxide; the closed outer layer is prepared from the following preparation raw materials in percentage by mass: 1-5% of FDTS, 5-15% of nano titanium oxide, 0.5-3% of graphite fluoride, 10-20% of DMF and the balance of electronic-grade epoxy resin.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sensor core, in particular to a double diaphragm sputtering thin film core and application thereof. BACKGROUND

[0002] In the fields of industrial production, energy development, and biomedical, as a core detection element, pressure sensors need to work stably in extreme medium environments such as high viscosity, strong corrosion, and easy crystallization for a long time, for example, sulfur-containing crude oil in oil and gas exploration, acid and alkali solution in chemical industry, high-impurity wastewater in wastewater treatment, and body fluid detection in biomedical. However, the existing pressure sensor core has the problems of poor measurement stability and short service life under the above working conditions. The core problems are concentrated in two aspects of medium erosion and structural design defects, which seriously restrict the application range and reliability of the sensor.

[0003] From the perspective of medium erosion, the traditional pressure sensor's Wheatstone bridge diaphragm adopts single-layer protective film or simple organic coating (such as PI protective film, multi-layer composite CPP protective film) for protection. Among them, the PI protective film can prevent short circuit of current for a short time, but it has poor chemical corrosion resistance and is easy to swell and crack in strong acid and alkali medium, resulting in direct exposure and erosion of the resistance strain layer; the multi-layer composite CPP protective film combines barrier layer and adhesive layer through co-extrusion technology, which can improve the protection ability to a certain extent, but the temperature resistance and durability of organic materials are limited, and under the long-term attachment and erosion of high-viscosity medium (such as crude oil, syrup), the coating is easy to peel off, thereby causing the failure of the sensor. Even though some special sensors (such as Weika DSS22T diaphragm sealed pressure sensor) isolate the erosive medium through a diaphragm sealing system, the composition of the diaphragm is not disclosed, and the pressure conduction lag problem caused by the complex structure has not been solved, and the high production cost limits its large-scale application.

[0004] From the perspective of structural design defects, the existing sensor core generally relies on a pressure guide hole to realize the contact between the medium and the pressure sensing element, and this structure is prone to cause hole blockage in high-viscosity and easy-crystallization media. For example, when detecting the pressure of fruit beverage in the food processing field, fruit particles or colloidal particles are easy to accumulate in the pressure guide hole; when measuring the pressure of a solution containing solute in chemical production, the solute is easy to crystallize on the inner wall of the hole, not only causing the interruption of pressure conduction, but also requiring frequent disassembly and cleaning, increasing the maintenance cost and downtime risk. In addition, the interlayer structure of the sensor core lacks coordination: on the one hand, the difference between the thermal expansion coefficients of the metal substrate and the protective layer is large, which is easy to produce interlayer stress under temperature fluctuation conditions, resulting in cracking of the protective film; on the other hand, the connection mode (such as adhesion, ordinary welding) between the pressure sensing diaphragm and the Wheatstone bridge diaphragm has the problems of insufficient rigidity or stress concentration, and uneven deformation is easy to occur during pressure conduction, which directly affects the measurement accuracy and repeatability.

[0005] Further analysis of the key functional layers of the sensor core shows that there is also room for optimization in the performance of the insulating layer and the resistive strain layer. Traditional insulating layers mostly use SiO2 or Al2O3, and the dielectric constant stability is easily affected by humidity and ion penetration in a strong corrosive environment, leading to zero drift of the Wheatstone bridge; the commonly used constantan and nickel-chromium alloy of the resistive strain layer has a certain strain sensitivity, but is easily oxidized in high-temperature and corrosive media, leading to resistance value drift and thus reducing the long-term measurement accuracy of the sensor. At the same time, the existing protective layer lacks a protective-conductive collaborative design: some protective layers excessively pursue high hardness to resist erosion, but ignore toughness and thermal conductivity, causing the diaphragm to easily produce micro-cracks under pressure cycling; some protective layers focus on hydrophobicity, but due to insufficient interfacial bonding strength, interlayer peeling occurs under long-term immersion in the medium, and a sustained and effective protective barrier cannot be formed. SUMMARY

[0006] The present application is to overcome the above technical problems, and therefore provides a double-diaphragm sputtered thin film core and its application.

[0007] The present application solves the above technical problems by the following technical solutions. The core includes a pressure-sensing diaphragm and a Wheatstone bridge diaphragm, the Wheatstone bridge diaphragm is provided with a stainless steel substrate, an insulating layer, a resistive strain layer, and a protective layer including a transition bottom layer, a protective intermediate layer, and a closed outer layer from bottom to top, the pressure-sensing diaphragm is provided with a steel base, an elastic layer, and an oxidation-resistant layer from bottom to top, and the core does not contain a pressure-conducting channel, which not only avoids the problem of channel blockage, but also enables the core to be measured for a long time in a medium with high viscosity and strong corrosion through the design of the diaphragm structure.

[0008] The double-diaphragm sputtered thin film core includes a pressure-sensing diaphragm and a Wheatstone bridge diaphragm, the Wheatstone bridge diaphragm is provided with a protective layer, and the protective layer includes a transition bottom layer, a protective intermediate layer, and a closed outer layer from bottom to top. The protective intermediate layer is composed of the following mass fraction of preparation raw materials: 10-25% nanometer alumina, 3-9% nanometer zirconia, 0.5-3.0% boron nitride nanotube, and the balance nanometer silicon dioxide. The closed outer layer is composed of the following mass fraction of preparation raw materials: 1-5% FDTS, 5-15% nanometer titanium oxide, 0.5-3% fluorinated graphite, 10-20% DMF (N,N-dimethylformamide), and the balance electronic-grade epoxy resin.

[0009] In some preferred embodiments, the preparation raw materials of the protective intermediate layer include, by mass fraction: 12-23% nanometer alumina, 4-7% nanometer zirconia, 0.6-2.1% boron nitride nanotube, and the balance nanometer silicon dioxide. Among them, the nanometer alumina in the intermediate protective layer provides hardness, the nanometer zirconia provides toughness, and the two together achieve high strength and high toughness; the boron nitride nanotube has good thermal conductivity and strength.

[0010] In some preferred embodiments, the preparation raw materials of the closed outer layer include, by mass fraction, 2-4% of FPTS, 7-12% of nano titanium oxide, 0.5-1.8% of fluorinated graphite, 12-17% of DMF, and the balance of electronic-grade epoxy resin.

[0011] The electronic-grade epoxy resin in the closed outer layer serves as a matrix resin, having excellent adhesion and chemical corrosion resistance; the FPTS as a surface modifier can enhance the hydrophobicity and corrosion resistance of the material surface; the nano titanium oxide has excellent oxidation resistance; and the fluorinated graphite as a solid lubricant has the characteristics of low surface energy, excellent thermal stability and chemical stability.

[0012] In some preferred embodiments, the thickness of the transition bottom layer is 0.1-0.5 μm, preferably 0.2-0.3 μm.

[0013] In some preferred embodiments, the thickness of the protective intermediate layer is 1.5-10 μm, preferably 5-10 μm.

[0014] In some preferred embodiments, the thickness of the closed outer layer is 5-30 μm, preferably 5-10 μm.

[0015] The preparation method of the protective intermediate layer includes mixing the preparation raw materials and then spraying them on the surface of the transition bottom layer by plasma spraying to form the protective intermediate layer.

[0016] The preheating temperature of the plasma spraying is 150-200 °C.

[0017] The power of the plasma spraying is 40-60 kW.

[0018] The gas flow of the plasma spraying is 40 L / min of Ar and 10 L / min of He.

[0019] The powder feeding speed of the plasma spraying is 15-25 g / min.

[0020] The preparation method of the closed outer layer includes mixing the preparation raw materials by ultrasonic assistance, obtaining a sealing agent, and then spin-coating the sealing agent on the protective intermediate layer to obtain the protective layer after curing.

[0021] In some preferred embodiments, the rotation speed of the spin-coating is 1000-5000 rpm, preferably 3000 rpm.

[0022] In some preferred embodiments, the temperature of the spin-coating is 20-30 °C, for example, 25 °C.

[0023] In some preferred embodiments, the component of the transition bottom layer is titanium carbide, preferably Ti x C1-x x=0.5~0.8.

[0024] In some preferred embodiments, the preparation method of the transition bottom layer comprises: depositing a titanium carbide layer by magnetron sputtering method with titanium target and methane.

[0025] In some preferred embodiments, the methane needs to be diluted with argon, and the volume ratio of methane to argon is 1:1~20.

[0026] In some preferred embodiments, the substrate temperature of the magnetron sputtering is 360~420℃, preferably 400℃.

[0027] In some preferred embodiments, the particle size of the nano-aluminum oxide is 30~60nm, preferably 30~50nm.

[0028] In some preferred embodiments, the nano-zirconium oxide D50=30~50nm.

[0029] In some preferred embodiments, the thermal conductivity coefficient of the boron nitride nanotube is 3000W / m·K.

[0030] In some preferred embodiments, the Young's modulus of the boron nitride nanotube is 1.18TPa.

[0031] In some preferred embodiments, the D50 of the nano-silicon dioxide is 10~30nm.

[0032] In some preferred embodiments, the electronic-grade epoxy resin is a mixed epoxy resin of bisphenol A and bisphenol F.

[0033] In some preferred embodiments, the nano-titanium oxide D50=15~30nm.

[0034] In some preferred embodiments, the D50 of the graphite fluoride is 5~10μm.

[0035] In the present application, the Wheatstone bridge diaphragm comprises, from bottom to top, a stainless steel substrate, an insulation layer, a resistive strain layer and a protective layer.

[0036] In some preferred embodiments, the composition of the insulation layer is Ta2O5.

[0037] In some preferred embodiments, the thickness of the insulation layer is 1.5~2.5μm, preferably 1.8~2.2μm.

[0038] In some preferred embodiments, the composition of the electric resistance strain layer is a Kama alloy, which comprises 0.5-1.5% Mn, Si≤0.2%, 19.0-21.5% Cr, 2.7-3.2% Al, 2.0-3.0% Fe and the balance of Ni in terms of mass percentage.

[0039] In some preferred embodiments, the thickness of the electric resistance strain layer is 50-100 nm.

[0040] The composition of the wire-bonding layer is Au.

[0041] The pressure-sensitive diaphragm comprises, from bottom to top, a steel base, an elastic layer and an oxidation-resistant layer.

[0042] In some preferred embodiments, the composition of the elastic layer is Ni 60-75 Si 10-20 B, for example, Ni 68 Si 15 B 17 .

[0043] In some preferred embodiments, the thickness of the elastic layer is 0.5-4 μm, preferably 1-3 μm.

[0044] In some preferred embodiments, the composition of the oxidation-resistant layer is SiO2.

[0045] In some preferred embodiments, the thickness of the oxidation-resistant layer is 0.5-1.5 μm, preferably 0.5-1 μm.

[0046] The aforementioned double-diaphragm sputtering thin-film core is applicable in the fields of petroleum and natural gas, chemical industry, waste water treatment, biomedicine and food processing.

[0047] On the basis of common general knowledge in the art, the above-mentioned preferred conditions can be combined at will, thus obtaining various preferred examples of the present application.

[0048] Compared with the prior art, the present application has the following advantages: 1. The protective layer material of the Wheatstone bridge diaphragm of the application is selected as follows: the composition of the transition bottom layer is titanium carbide, which can effectively solve the thermal expansion mismatch problem of the metal and the protective layer, avoid structural damage caused by the difference in thermal expansion, and improve the reliability and service life of the sensor; the combination of the materials used in the protective intermediate layer makes the protective intermediate layer have high hardness, high toughness, good thermal conductivity and strength, and can effectively resist the erosion of high-viscosity and strong corrosive media on the sensor; the electronic grade epoxy resin is used as the base resin in the preparation of the closed outer layer, which has excellent adhesion and chemical corrosion resistance; FDTS is used as a surface modifier to enhance the hydrophobicity and corrosion resistance of the material surface; nano titanium oxide has excellent oxidation resistance; and the fluorinated graphite is used as a solid lubricant, which has low surface energy, excellent thermal stability and chemical stability.

[0049] 2. From the structural design: the double diaphragm structure of the Wheatstone bridge diaphragm and the pressure sensing diaphragm is separately arranged, the fixed base and the pressure conducting rod are matched to form a pressure transmission path without a pressure guide hole, the pressure sensing diaphragm directly contacts the medium to sense the pressure, and then the pressure is accurately transmitted to the Wheatstone bridge diaphragm by the pressure conducting rod, which fundamentally avoids the problem that the traditional pressure guide hole is easily blocked by high-viscosity and easily-crystallized media, and the stress relief groove of the fixed base can effectively release the welding stress and pressure strain to ensure linear pressure transmission; the Wheatstone bridge diaphragm is provided with a stainless steel base, an insulating layer, a resistance strain layer and a protective layer from bottom to top, and the protective layer is further divided into a transition bottom layer, a protective intermediate layer and a closed outer layer in a gradient structure, the transition bottom layer can alleviate the thermal expansion mismatch between the layers to avoid cracking and peeling of the protective layer, and the protective intermediate layer and the closed outer layer cooperate to improve the protection effect and reduce the influence of the external environment on the resistance strain layer; the pressure sensing diaphragm is provided with a steel base, an elastic layer and an oxidation-resistant layer from bottom to top to ensure stable pressure sensing in the medium, and the overall structural design enables the core to accurately measure in high-viscosity and strong corrosive media for a long time. BRIEF DESCRIPTION OF DRAWINGS

[0050] In order to facilitate the understanding of those skilled in the art, the application will be further described below with reference to the accompanying drawings.

[0051] Figure 1 It is a schematic diagram of the appearance of the double diaphragm sputtering film core.

[0052] Figure 2 It is an exploded view of the double diaphragm sputtering film core.

[0053] Figure 3 It is a sectional view of the double diaphragm sputtering film core.

[0054] Figure 4 It is a schematic diagram of the Wheatstone bridge diaphragm structure.

[0055] Figure 5 It is a schematic diagram of the pressure sensing diaphragm structure.

[0056] BRIEF DESCRIPTION OF DRAWINGS 100, strain sensing diaphragm assembly; 110, strain sensing base; 120, Wheatstone bridge diaphragm; 130, force conducting rod; 200, connecting fixing seat; 210, fixing seat; 220, stress release groove; 300, pressure sensing diaphragm assembly; 310, pressure sensing diaphragm seat body; 320, pressure sensing diaphragm; 11, protective layer; 12, wire bonding layer; 13, resistance strain layer; 14, insulating layer; 15, stainless steel substrate; 111, closed outer layer; 112, protective intermediate layer; 113, transition bottom layer; 31, oxidation-resistant layer; 32, elastic layer; 33, steel base. DETAILED DESCRIPTION

[0057] In order to facilitate the understanding of the present application, the following will be a more comprehensive and detailed description of the preferred embodiments of the present application, but the protection scope of the present application is not limited to the following specific embodiments.

[0058] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present application.

[0059] Structure of double diaphragm sputtering film core The double diaphragm sputtering film core of the present application, the product structure schematic diagram is shown in Figures 1-3 ; wherein, Figure 1 is a schematic diagram of the appearance of the double diaphragm sputtering film core, Figure 2 is an exploded view of the double diaphragm sputtering film core, Figure 3 is a sectional view of the double diaphragm sputtering film core.

[0060] 1. The structure of the double diaphragm sputtering film core of the present application is as follows: The strain sensing diaphragm assembly (100) comprises a strain sensing base (110), a Wheatstone bridge diaphragm (120) and a force conducting rod (130); the Wheatstone bridge diaphragm (120) is arranged on the strain sensing base (110), and the force conducting rod (130) is fixedly connected with the Wheatstone bridge diaphragm (120) and used for conducting pressure to the Wheatstone bridge diaphragm (120) so that the resistance value of the piezoresistive strain gauge thereon changes to output a pressure signal; The connecting fixture (200) includes a fixture (210) and a stress relief groove (220). The connecting fixture (200) serves as an intermediate connection, stably connecting the strain sensing diaphragm assembly (100) and the pressure sensing diaphragm assembly (300). The stress relief groove (220) can reduce the internal stress of the structure and ensure the stability of the connection and the overall structure. The pressure sensing membrane assembly (300) includes: a pressure sensing membrane base (310) and a pressure sensing diaphragm (320); the pressure sensing membrane base (310) is a support base for the pressure sensing membrane assembly (300), and an annular mounting groove adapted to the pressure sensing diaphragm (320) is provided inside it; the bottom of the pressure sensing diaphragm (320) is sealed and fixed to the mounting groove by laser welding; The strain sensing diaphragm assembly (100), the connecting fixture (200), and the pressure sensing diaphragm assembly (300) are all fixedly connected by laser welding, which allows the pressure-sensing diaphragm (320) and the Wheatstone bridge diaphragm (120) to be connected by a force transmission rod (130) to achieve force transmission.

[0061] Among them, the strain sensing base (110), force transmission rod (130), fixing base (210), and pressure-sensing diaphragm base (310) can be made of stainless steel, which is commonly used in this field. In this invention, 17-4 PH stainless steel is used.

[0062] 2. Wheatstone bridge diaphragm See the schematic diagram of the Wheatstone bridge diaphragm structure. Figure 4 ; An insulating layer (14) is provided on top of a stainless steel substrate (15). A resistance strain layer (13) is provided on a portion of the surface of the insulating layer (14), and a wire bonding layer (12) is provided on another portion. A protective layer (11) is provided on the surface of the resistance strain layer (13), and the wire bonding layer penetrates the resistance strain layer (13) and the protective layer (11). The stainless steel substrate (15) is part of the strain sensing base (110). The protective layer (11) consists of a transitional bottom layer (113), a protective intermediate layer (112), and a closed outer layer (111) from bottom to top.

[0063] 3. Pressure-sensitive diaphragm See the schematic diagram of the pressure-sensitive diaphragm structure. Figure 5 ; An elastic layer (32) is provided above the steel base (33), and an anti-oxidation layer (31) is provided on the surface of the elastic layer (32); wherein, the steel base (33) is part of the pressure-sensitive membrane seat (310).

[0064] Ni-containing materials were deposited on a stainless steel substrate using magnetron sputtering with Ni, Si, and B targets. 68 Si 15 B 17The elastic layer has a thickness of 2.0 μm. The substrate temperature is 260 °C, the target-substrate distance is 5 cm, the sputtering speed is 10 nm / min, the power of the Ni target is 150 W, the power of the Si target is 100 W, and the power of the B target is 80 W.

[0065] An oxidation-resistant layer is deposited on the surface of the elastic layer by magnetron sputtering. The thickness of the oxidation-resistant layer is 0.8 μm.

[0066] The raw material information used in the following examples is as follows: The boron nitride nanotube is purchased from GuTesu (Shanghai) Trade Co., Ltd. The thermal conductivity is 3000 W / m·K, the Young's modulus is 1.18 TPa, and the thermal expansion coefficient is 1×10 -6 ; The nano-aluminum oxide is purchased from Hangzhou Hengna New Material Co., Ltd. HN-L100, 30-50 nm, content ≥99.999%, crystal form is alpha phase.

[0067] The nano-zirconium oxide D50=50 nm, content ≥99.9%, crystal phase is monoclinic phase.

[0068] The nano-silicon oxide D50=15 nm, content ≥99.8%, specific surface area is 250±30 m 2 / g.

[0069] FDTS: Chinese name: trichloro(1H,1H,2H,2H-perfluorooctyl) silane, CAS number: 78560-45-9.

[0070] The nano-titanium oxide D50=15-25 nm, content ≥99.9%, specific surface area is 100-250 m 2 / g.

[0071] The fluorinated graphite is purchased from Shanghai Fluorine Rui Fine Chemical Co., Ltd. Fluorinated graphite CF500, CAS number: 51311-17-2, D50=5-10 μm, tap density is 0.9 g / cm 3 .

[0072] The electronic-grade epoxy resin is purchased from Hunan Sailve New Material Technology Co., Ltd. SAW-1100R bisphenol A and bisphenol F type epoxy resin, epoxy equivalent weight is 160-170 g / eq, viscosity (25 °C) is 2000-4000 cps.

[0073] The Kama alloy composition is 0.63% Mn, Si ≤0.15%, 21% Cr, 3.1% Al, 2.4% Fe, and the balance of Ni. Including but not limited to the above manufacturers and models.

[0074] The Wheatstone bridge diaphragm used in different examples and comparative examples is as follows: Embodiment 1 1. The Wheatstone bridge diaphragm of this embodiment comprises, from bottom to top, a stainless steel substrate, an insulation layer, a resistive strain layer, a bonding wire layer and a protective layer; The insulation layer is composed of Ta2O5, and the thickness of the insulation layer is 2.0 μm; The resistive strain layer is composed of Karma alloy, and the thickness of the resistive strain layer is 75 nm; The bonding wire layer is composed of Au; The protective layer comprises, from bottom to top, a 0.27 μm transition bottom layer, an 8 μm protective intermediate layer and a 10 μm closed outer layer.

[0075] The transition bottom layer is composed of Ti 0.6 C 0.4 ; The protective intermediate layer is composed of, by mass fraction, 17.6% nano-alumina, 5.4% nano-zirconia, 1.8% boron nitride nanotubes and the balance of nano-silicon dioxide; The closed outer layer is composed of, by mass fraction, 3.5% FDTS, 8.4% nano-titanium oxide, 1.6% fluorinated graphite, 13% DMF and the balance of electronic-grade epoxy resin.

[0076] 2. The Wheatstone bridge diaphragm of this embodiment is prepared as follows: (1) The Ta2O5 insulation layer is prepared on the stainless steel substrate by atomic deposition method; specifically, the preparation method is that the temperature of the steel substrate is 250°C, the temperature of the Ta(OC2H5)5 source bottle is 180°C, the nitrogen flow rate is 6 sccm, and the deposition rate is 9.3 Å / s at 3 MPa.

[0077] (2) The resistive strain layer is prepared by plating a layer of Karma alloy on the surface of the insulation layer using a magnetron sputtering method, and the substrate temperature during the magnetron sputtering process is 150°C, and the vacuum degree is 1×10 -3 Pa; the resistive strain layer is patterned.

[0078] (3) The bonding wire layer is deposited by a magnetron sputtering method, and the bonding wire layer is then patterned.

[0079] (4) Protective layer preparation: a. Transition bottom layer preparation: titanium target and methane are deposited by a magnetron sputtering method to form a titanium carbide layer (Ti 0.6 C 10.4 ); the magnetron sputtering power is 200 W, the substrate temperature is 400°C, and the volume ratio of methane to argon is 1:20; b. Preparation of the protective intermediate layer: the raw materials for preparing the protective intermediate layer were mixed and then formed on the surface of the transition bottom layer by plasma spraying, the preheating temperature of plasma spraying was 185°C, the power was 60 kW, the Ar flow rate was 40 L / min, the He flow rate was 10 L / min, and the powder feeding speed was 20 g / min during the process; c. Preparation of the sealing outer layer: the raw materials for preparing the sealing outer layer were mixed by ultrasonic assistance to obtain a sealing agent, and the sealing agent was spin-coated on the protective intermediate layer, the spin-coating speed was 3000 rpm, and the spin-coating temperature was 25°C, and the sealing outer layer was obtained after solidification.

[0080] Example 2 The difference between this example and Example 1 is only that: The raw materials for preparing the protective intermediate layer consisted of 21% nano-alumina, 4.3% nano-zirconia, 1.9% boron nitride nanotubes, and the balance nano-silica by mass fraction; the other raw materials, steps, and parameters were the same as in Example 1.

[0081] Example 3 The difference between this example and Example 1 is that: The raw materials for preparing the sealing outer layer consisted of 2.7% FTS, 7.1% nano-titanium oxide, 0.7% fluorinated graphite, 17% DMF, and the balance electronic-grade epoxy resin by mass fraction; the other raw materials, steps, and parameters were the same as in Example 1.

[0082] Example 4 The difference between this example and Example 1 is that: The composition of the transition bottom layer was Ti 0.52 C 0.48 ; During the preparation process of the transition bottom layer, the substrate temperature was 360°C during magnetron sputtering, and the volume ratio of methane to argon was 1:12; the other raw materials, steps, and parameters were the same as in Example 1.

[0083] Example 5 The difference between this comparative example and Example 1 is that: The raw materials for preparing the protective intermediate layer consisted of 20% nano-alumina, 7% nano-zirconia, 2.0% boron nitride nanotubes, and the balance nano-silica by mass fraction; The other raw materials, steps, and parameters were the same as in Example 1.

[0084] Comparative Example 1 The difference between this comparative example and Example 1 is that: The raw materials for preparing the protective intermediate layer consisted of 22% nano-alumina, 6.3% nano-zirconia, and the balance nano-silica by mass fraction; the other raw materials, steps, and parameters were the same as in Example 1.

[0085] Comparative Example 2 The difference between this comparative example and Example 1 is that: The raw materials for preparing the protective intermediate layer consisted of 18% nanometer alumina, 6.5% nanometer zirconia, 4.0% boron nitride nanotubes, and the balance nanometer silicon dioxide by mass fraction; other raw materials, steps, and parameters were the same as in Example 1.

[0086] Comparative Example 3 The difference between this comparative example and Example 1 is that: The raw materials for preparing the protective intermediate layer consisted of 18% nanometer alumina, 6.5% nanometer zirconia, 4.0% boron nitride nanotubes, and the balance nanometer silicon dioxide by mass fraction; other raw materials, steps, and parameters were the same as in Example 1.

[0087] Comparative Example 4 The difference between this comparative example and Example 1 is that: The raw materials for preparing the protective intermediate layer consisted of 18% nanometer alumina, 6.5% nanometer zirconia, 4.0% boron nitride nanotubes, and the balance nanometer silicon dioxide by mass fraction; other raw materials, steps, and parameters were the same as in Example 1.

[0088] Application performance of double diaphragm sputtering film core The double diaphragm sputtering film cores prepared in the above examples and comparative examples were tested for various performances. The test medium was sulfur-containing crude oil (sulfur content 1.2%, viscosity 500 mPa·s), the test environment temperature was 85°C, the relative humidity was 50% RH, and the test equipment was a high-temperature high-pressure simulated wellbore. Test steps: (1) Initial calibration: In a standard environment (23°C, normal pressure), all sensors were calibrated for zero point and full scale (99 MPa), and the initial sensitivity, linear error, and basic error were recorded. (2) Medium circulation test: The sensor was immersed in the high-temperature high-pressure simulated wellbore petroleum medium, and the following process was repeated 10 times: a. Pressure rising stage: from 0 MPa to 99 MPa in 30 s, and stably maintained for 5 min; b. Pressure dropping stage: from 99 MPa to 0 MPa in 30 s, and stably maintained for 5 min; c. Medium replacement: new petroleum medium was replaced after each cycle to simulate the medium update under actual working conditions. (3) Performance retest: after 10 cycles, the sensor was removed and the surface was cleaned, then it was recalibrated at 25℃, and the output values of several pressure points (-0.011 MPa, 16.497 MPa, 32.996 MPa, 49.498 MPa, 65.994 MPa, 82.498 MPa, 98.998 MPa) were recorded. The standard device was HB600F1 pressure calibrator, the measurement range was (0~100) MPa, and the test was carried out according to JJG860-2015 "Pressure Sensor (Static)", and the data after processing obtained Table 1.

[0089]

[0090] According to the above application test results, it can be seen that: Comparative Example 1 lacks the high-thermal-conductivity characteristics of boron nitride nanotubes, and the local heat accumulation of the diaphragm causes uneven deformation caused by temperature gradient, and the linear error is large; at the same time, the interlayer bonding strength decreases, and the diaphragm deformation consistency is poor under pressure loading; Comparative Example 2 has too high a content of boron nitride nanotubes, which is easy to form agglomeration in the layer, resulting in uneven internal structure of the diaphragm, and stress concentration area appears during pressure conduction, and the repeatability error and hysteresis error are significantly higher than those of Example 1; Comparative Example 3 lacks the hydrophobic effect of FDTS, and high-viscosity medium is easy to adhere to the surface of the closed outer layer, and even penetrates into the protective intermediate layer, resulting in diaphragm moisture or corrosion; at the same time, the medium adhesion increases the additional mass of the diaphragm, and "hysteresis effect" appears during pressure conduction, and the hysteresis error and linear error are both high; Comparative Example 4 lacks the lubricating effect of fluorinated graphite, and the frictional resistance between the diaphragm and the medium increases, and the diaphragm deformation recovery speed slows down during pressure loading / unloading, and the hysteresis error increases; this comparative example lacks the buffering function of fluorinated graphite, and the impact of the medium on the diaphragm is directly transmitted to the resistance strain layer, resulting in an increase in signal fluctuation, and the repeatability error is higher than that of Example 1, and the sensitivity deviation increases to 0.100%.

[0091] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or prepared by existing methods. The above specific examples further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above examples are only specific embodiments of the present application and are not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A dual diaphragm sputter thin film core comprising a pressure sensitive diaphragm and a Wheatstone bridge diaphragm, characterized in that, The Wheatstone bridge membrane is provided with a protective layer, and the protective layer comprises a transition bottom layer, a protective intermediate layer and a closed outer layer from bottom to top. The protective intermediate layer is composed of the following mass fraction of raw materials: 10-25% nano-alumina, 3-9% nano-zirconia, 0.5-3.0% boron nitride nanotubes, and the balance of nano-silicon dioxide. The closed outer layer is composed of the following mass fraction of raw materials: 1-5% FDTS, 5-15% nano-titanium oxide, 0.5-3% fluorinated graphite, 10-20% DMF, and the balance of electronic-grade epoxy resin.

2. The dual diaphragm sputter film core of claim 1, wherein, At least one of the following conditions a-c is met: a. The thickness of the transition bottom layer is 0.1-0.5 μm; b. The thickness of the protective intermediate layer is 1.5-10 μm; c. The thickness of the closed outer layer is 5-30 μm.

3. The dual diaphragm sputter thin film core of claim 1, wherein, At least one of the following conditions a-c is met for the Wheatstone bridge membrane: a. The preparation method of the transition bottom layer comprises: depositing a titanium carbide layer by magnetron sputtering method with titanium target and methane; b. The preparation method of the protective intermediate layer comprises: mixing the raw materials and then spraying on the surface of the transition bottom layer by plasma to form the protective intermediate layer; c. The preparation method of the closed outer layer comprises: mixing the raw materials by ultrasonic assistance to obtain a sealing agent, and then spin coating the sealing agent on the protective intermediate layer and curing.

4. The dual diaphragm sputter-deposited thin film core of claim 3, wherein, At least one of the following conditions a-c is met: a. The preheating temperature of the plasma spraying is 150-200°C; b. The power of the plasma spraying is 40-60 kW; c. The powder feeding speed of the plasma spraying is 15-25 g / min; d. The transition layer has a composition of TixC 1-x , x = 0.5 ~ 0.

8.

5. The dual diaphragm sputter film core of claim 1, wherein, At least one of the following conditions a-c is met: a. The particle size of the nano-alumina is 30-60 nm; b. The nano-zirconia D50=30-50 nm; c. The thermal conductivity coefficient of the boron nitride nanotube is 3000 W / m·K; d. The D50 of the nano-silicon dioxide is 10-30 nm; e. The electronic-grade epoxy resin is a mixed epoxy resin of bisphenol A and bisphenol F; f. The nano-titanium oxide D50=15-30 nm; g. The D50 of the fluorinated graphite is 5-10 μm.

6. The dual diaphragm sputter thin film core of claim 1, wherein, The Wheatstone bridge membrane comprises a stainless steel substrate, an insulating layer, a resistance strain layer and a protective layer from bottom to top.

7. The dual diaphragm sputter-deposited thin film core of claim 6, wherein, At least one of the following conditions a-d is met for the Wheatstone bridge membrane: a. The composition of the insulating layer is Ta2O5; b. The thickness of the insulating layer is 1.5-2.5 μm; c. The composition of the resistance strain layer is Karma alloy; d. The thickness of the resistance strain layer is 50-100 nm.

8. The dual diaphragm sputter-deposited thin film core of claim 1, wherein, The pressure sensing membrane comprises a steel base, an elastic layer and an oxidation-resistant layer from bottom to top.

9. The dual diaphragm sputter-deposited thin film core of claim 8, wherein, At least one of the following conditions a-c is met for the pressure sensing membrane: a. the elastic layer has a composition of N 60-75 Si 10-20 B; b. The thickness of the elastic layer is 0.5-4 μm; c. The composition of the oxidation-resistant layer is SiO2; d. The thickness of the oxidation-resistant layer is 0.5-1.5 μm.

10. The application of the double-membrane sputtering thin film core in the fields of petroleum and natural gas, chemical industry, wastewater treatment, biomedicine and food processing according to any one of claims 1-9.

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