A differential pressure sensor core and a preparation method thereof, and a differential pressure sensor

Abstract

The application discloses a differential pressure sensor core and a preparation method thereof and a differential pressure sensor, and belongs to the technical field of differential pressure sensor cores, and comprises a nano film, wherein the nano film is composed of a composite transition layer, an insulating layer, a composite strain layer, a pad layer and a protective layer from bottom to top; the composite strain layer is a three-layer structure composed of an elastic layer, a precision layer and a stress layer from bottom to top, the elastic layer is a NiCrMnTi alloy layer, the precision layer is a NiCrAlMnSiWTa alloy layer, and the stress layer is a NiCrMoV alloy layer. The composite transition layer and the composite strain layer in the nano film of the differential pressure sensor core solve the problems of low precision, poor stability and short service life of a traditional differential pressure sensor core under a large differential pressure, and realize accurate measurement and long-term stability under a high-differential-pressure scene.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of differential pressure sensor cores, and specifically relates to a differential pressure sensor core and a preparation method thereof and a differential pressure sensor. BACKGROUND

[0002] As an important pressure detection element, a differential pressure sensor is widely used in the fields of aerospace, automobile industry, petroleum and chemical industry, medical equipment, etc., and the core performance thereof depends on the measurement accuracy, stability and service life of the core. With the increasing requirements of industrial scenes on differential pressure measurement, especially in harsh environments such as large differential pressure fluctuation and high-low temperature alternation, the traditional differential pressure sensor core gradually exposes the performance short board.

[0003] The prior art adopts a single-layer transition layer, a single-layer insulation layer and a single-layer strain layer of a nano thin film structure, and attempts to improve the core performance by adjusting the thickness or composition of the single film layer. However, such improvement has significant defects: on the one hand, the single-layer transition layer is difficult to simultaneously meet the adaptability requirements of the metal substrate (such as stainless steel) and the insulation layer, and is prone to insufficient interface bonding force, and film layer peeling occurs under the repeated action of large differential pressure; on the other hand, the single-layer strain layer needs to simultaneously consider the functions of elastic buffering and precision sensing, resulting in a contradiction in performance design, that is, either the elasticity is insufficient to withstand overload pressure, or the precision control is difficult, and the temperature drift is significant, so it is difficult to balance the measurement accuracy and service life. SUMMARY

[0004] In order to overcome the above technical problems, the present application provides a differential pressure sensor core and a preparation method thereof and a differential pressure sensor. The composite transition layer and the composite strain layer of the differential pressure sensor core of the present application solve the problems of low accuracy, poor stability and short service life of the traditional differential pressure sensor core under large differential pressure, and realize accurate measurement and long-term stability in a high differential pressure scene.

[0005] The present application solves the above technical problems through the following technical solutions.

[0006] The present application discloses a differential pressure sensor core, comprising a nano thin film, from bottom to top, the nano thin film is composed of a composite transition layer, an insulation layer, a composite strain layer, a pad layer and a protective layer;

[0007] From bottom to top, the composite strain layer is a three-layer structure composed of an elastic layer, a precision layer and a stress layer, the elastic layer is a NiCrMnTi alloy layer, the precision layer is a NiCrAlMnSiWTa alloy layer, and the stress layer is a NiCrMoV alloy layer.

[0008] According to some embodiments of the present application, the composite transition layer is a double-layer structure composed of a transition bottom layer and a transition top layer, the transition bottom layer is a TiNbZrMo alloy layer, and the transition top layer is a TaHfTi alloy layer.

[0009] According to some embodiments of the present application, the mass percentage of the TiNbZrMo alloy layer is: 25%~35% Nb, 7%~13% Zr, 2%~5% Mo, and the balance of Ti; preferably, the mass percentage of the TiNbZrMo alloy layer is: 28%~32% Nb, 9%~11% Zr, 3%~4% Mo, and the balance of Ti. Ti is the base component, which has excellent metal compatibility and deposition film forming capability, and can form a preliminary metallurgical bond with the stainless steel substrate; the addition of 25%~35% Nb can reduce the elastic modulus of the alloy, so that the mechanical properties of the transition bottom layer and the stainless steel substrate are more matched, and the interlayer stress when the core body deforms is reduced; the introduction of 7%~13% Zr can improve the corrosion resistance and high temperature stability of the alloy, and avoid oxidation failure of the bottom layer in harsh environments; the addition of 2%~5% Mo can further enhance the interfacial bonding strength, promote the element interdiffusion between the transition bottom layer and the substrate, and form a stable interfacial bonding layer.

[0010] According to some embodiments of the present application, the mass percentage of the TaHfTi alloy layer is: 15%~25% Hf, 5%~10% Ti, and the balance of Ta; preferably, the mass percentage of the TaHfTi alloy layer is: 18%~22% Hf, 7%~9% Ti, and the balance of Ta. Ta is the base component, which has a high melting point, high chemical stability, and good compatibility with oxides, and can avoid chemical reaction with the insulating layer; the addition of 15%~25% Hf can optimize the surface energy of the alloy, and improve the deposition uniformity of the insulating layer; the introduction of 5%~10% Ti can enhance the interface adaptability of the transition top layer and the transition bottom layer, and Ti element can form a solid solution with Ti, Nb, and other elements in the transition bottom layer, further improving the bonding stability.

[0011] According to some embodiments of the present application, the thickness of the transition bottom layer is 40~130 nm, preferably 70~110 nm.

[0012] According to some embodiments of the present application, the thickness of the transition top layer is 40~120 nm, preferably 70~100 nm.

[0013] According to some embodiments of the present application, the insulating layer is an Al2O3-TiO2 layer; the mass ratio of Al2O3 to TiO2 in the Al2O3-TiO2 layer is 3~5:1.

[0014] According to some embodiments of the present application, the thickness of the insulating layer is 0.5~3 μm, preferably 0.8~1.2 μm.

[0015] According to some embodiments of the present application, the mass percentage of the NiCrMnTi alloy layer is: 20%~30% Cr, 5%~10% Mn, and 1%~3% Ti, and the balance of Ni; preferably, the mass percentage of the NiCrMnTi alloy layer is: 24%~26% Cr, 7%~9% Mn, and 1.5%~2.5% Ti, and the balance of Ni. Ni is the base component with excellent plasticity and film-forming ability, ensuring the deformability of the elastic layer; the addition of 20%~30% Cr can improve the corrosion resistance and oxidation resistance of the alloy, and the introduction of 5%~10% Mn can optimize the elastic modulus of the alloy.

[0016] According to some embodiments of the present application, the mass percentage of the NiCrAlMnSiWTa alloy layer is: 12%~18% Cr, 2%~4% Al, 6%~9% Mn, 0.6%~0.9% Si, 0.8%~1.2% W, 4.5%~5.5% Ta, and the balance of Ni; preferably, the mass percentage of the NiCrAlMnSiWTa alloy layer is: 14%~16% Cr, 2.5%~3.5% Al, 7%~8% Mn, 0.7%~0.8% Si, 0.9%~1.1% W, 4.8%~5.2% Ta, and the balance of Ni. Ni provides good electrical conductivity and film-forming uniformity; Cr can improve the oxidation resistance and structural stability of the alloy, avoiding drift caused by oxidation of the film layer; Al and Mn cooperate to optimize the strain sensitivity characteristics of the alloy, improving the deformation-resistance conversion efficiency; Si can enhance the density of the film layer and reduce resistance noise; the ratio of the key alloy elements W and Ta is the core of improving precision: W can reduce the temperature coefficient of the alloy, improving the temperature stability; Ta can optimize the crystal structure of the alloy, stabilizing the sensitivity coefficient.

[0017] According to some embodiments of the present application, the mass percentage of the NiCrMoV alloy layer is: 15%~25% Cr, 3%~6% Mo, 1%~3% V, and the balance of Ni; preferably, the mass percentage of the NiCrMoV alloy layer is: 18%~22% Cr, 4%~5% Mo, 1.5%~2.5% V, and the balance of Ni. Ni ensures the adaptability with the upper protective layer; Cr improves the corrosion resistance and oxidation resistance of the alloy, Mo can significantly enhance the stress diffusion ability of the alloy, dispersing the local concentrated stress of the precision layer to the entire stress layer; V can improve the hardness and mechanical strength of the alloy, while enhancing the interfacial bonding force between the stress layer and the precision layer.

[0018] According to some embodiments of the present application, the thickness of the elastic layer is 40~100 nm, preferably 60~80 nm.

[0019] According to some embodiments of the present application, the thickness of the precision layer is 30~80 nm, preferably 50~60 nm.

[0020] According to some embodiments of the present application, the stress layer has a thickness of 30-100 nm, preferably 60-90 nm.

[0021] According to some embodiments of the present application, the protective layer is a SiO2 layer at the bottom and a PI layer at the top.

[0022] According to some embodiments of the present application, the SiO2 layer has a thickness of 0.5-5 μm, preferably 0.5-2.0 μm, and more preferably 0.8-1.2 μm.

[0023] According to some embodiments of the present application, the PI layer has a thickness of 1.5-5 μm, preferably 2.5-4.0 μm, and more preferably 2.5-3.5 μm.

[0024] According to some embodiments of the present application, the pad layer is made of Au.

[0025] According to some embodiments of the present application, the pad layer has a thickness of 0.8-3 μm, preferably 0.8-1.5 μm.

[0026] According to some embodiments of the present application, the differential pressure sensor core comprises an elastic diaphragm, the surface of the elastic diaphragm is provided with an annular bridge arm, the annular bridge arm further comprises a pressure sensing arm, the pressure sensing arm is an integrated structural part of the annular bridge arm, the pressure deformation received by the annular bridge arm is conducted to the nano film through the pressure sensing arm, and the nano film is arranged on the upper surface of the pressure sensing arm.

[0027] According to some embodiments of the present application, the elastic diaphragm is a stainless steel substrate, and the material is 17-4PH stainless steel, 17-7PH stainless steel, 316 stainless steel, 316L stainless steel, 304 stainless steel, 304L stainless steel or 15-5PH stainless steel.

[0028] According to some embodiments of the present application, the elastic diaphragm has a thickness of 0.1-0.3 mm.

[0029] The present application also discloses a preparation method of the differential pressure sensor core.

[0030] S1. A transition bottom layer and a transition top layer are sequentially deposited on the surface of the elastic diaphragm by a magnetron sputtering method to form a composite transition layer.

[0031] S2. An insulating layer is deposited on the surface of the composite transition layer by an atomic layer deposition method.

[0032] S3. An elastic layer, a precision layer and a stress layer are sequentially deposited on the surface of the insulating layer by a magnetron sputtering method to form a composite strain layer.

[0033] S4. Depositing an Au layer on the surface of the composite strain layer by magnetron sputtering, and patterning to form a pad layer by a photolithography process;

[0034] S5. Depositing a SiO2 layer on the pad layer and the exposed area of the composite strain layer by chemical vapor deposition, coating PI glue by coating, and curing to obtain a protective layer;

[0035] S6. Annealing the prepared core to obtain a differential pressure sensor core.

[0036] S1. The elastic diaphragm also needs to be pretreated, i.e. sequentially subjected to degreasing, pickling, polishing, cleaning and drying.

[0037] In S1, the target materials for magnetron sputtering of the transition bottom layer and the transition top layer are TiNbZrMo alloy target and TaHfTi alloy target, respectively.

[0038] Further in S1, the components of the TiNbZrMo alloy target and the TaHfTi alloy target are prepared according to the component requirements of the transition bottom layer and the transition top layer.

[0039] In S1, the carrier gas for magnetron sputtering is Ar, and the carrier gas flow is 20-40 sccm.

[0040] In S1, the deposition temperature for magnetron sputtering is 150-250℃.

[0041] In S1, the power for magnetron sputtering is 150-300 W.

[0042] In S2, the preparation process of atomic layer deposition is that Al precursor, Ti precursor and H2O are deposited at a speed of 0.2-0.5 nm / cycle.

[0043] In S2, the deposition temperature for atomic layer deposition is 180-280℃.

[0044] In S3, the target materials for magnetron sputtering of the elastic layer, the precision layer and the stress layer are NiCrMnTi alloy target, NiCrAlMnSiWTa alloy target and NiCrMoV alloy target, respectively.

[0045] Further in S3, the components of the NiCrMnTi alloy target, the NiCrAlMnSiWTa alloy target and the NiCrMoV alloy target are prepared according to the component requirements of the elastic layer, the precision layer and the stress layer.

[0046] In S3, the carrier gas for magnetron sputtering is a mixed gas of Ar and N2, the volume ratio of Ar to N2 in the mixed gas is 10:1-20:1, and the carrier flow is 25-45 sccm.

[0047] In S3, the deposition temperature of the magnetron sputtering is 200-300 DEG C.

[0048] In S3, the power of the magnetron sputtering is 200-350 W.

[0049] In S4, the carrier gas of the magnetron sputtering is Ar, and the carrier gas flow is 30-50 sccm.

[0050] In S4, the deposition temperature of the magnetron sputtering is 100-200 DEG C.

[0051] In S4, the power of the magnetron sputtering is 180-280 W.

[0052] In S4, the photoetching and developing is pre-baking after spraying photoresist, re-exposure treatment, and hardening treatment after removing residual agent.

[0053] Further in S4, the pre-baking temperature is 85-120 DEG C, and the pre-baking time is 30-60 s.

[0054] Further in S4, the temperature during the exposure treatment is 20-30 DEG C.

[0055] Further in S4, the hardening treatment temperature is 100-130 DEG C.

[0056] In S5, the process of the chemical vapor deposition is that: the mixed gas of SiH4, N2O and Ar is used, the volume ratio is 1:5:10-1:8:15, the mixed gas flow is 40-80 sccm, and the deposition speed is 50-100 nm / min.

[0057] In S5, the process of the PI glue coating is that: the coating speed is 3000-5000 r / min for 30-60 s; the PI glue is a conventional PI glue in the art.

[0058] In S5, the curing process is that: preheating is carried out at 70-90 DEG C for 20-40 min, then sequentially holding at 110-130 DEG C, 170-190 DEG C and 220-260 DEG C for 50-70 min each, and finally naturally cooling to room temperature.

[0059] In S6, the annealing treatment process is that: holding at 300-400 DEG C for 120-180 min under the protection of inert gas; the inert gas is N2 or Ar, the heating rate is 5-10 DEG C / min, and the cooling rate is 3-5 DEG C / min. The annealing treatment can eliminate the internal stress generated in the deposition process of each film layer, promote the interdiffusion of interface elements, stabilize the lattice structure of the composite strain layer, and improve the long-term stability of the core.

[0060] The application further discloses a differential pressure sensor comprising the differential pressure sensor core.

[0061] On the basis of common general knowledge in the art, the above-mentioned preferred conditions can be combined arbitrarily, i.e. to obtain each preferred example of the present application.

[0062] Compared with the prior art, the present application has the following advantages:

[0063] The nanometer film structure adopted by the differential pressure sensor core of the present application can solve the technical problems of precision and stability of the existing differential pressure sensor. The core composite strain layer structure in the nanometer film includes three layers of elastic layer, precision layer and stress layer, which realizes the functional partition of overload buffering, precise sensing and stress dispersion. The elastic layer absorbs the overload pressure with low elastic modulus, the precision layer has high sensitivity coefficient and low temperature drift, and the stress layer diffuses local stress to avoid film layer cracking.

[0064] In addition, the transition bottom layer (TiNbZrMo) has high lattice matching degree with the stainless steel substrate, and the transition top layer (TaHfTi) forms a strong chemical bond with the insulating layer to improve the interlayer compatibility. The protective layer has high hardness of SiO2 and high flexibility of PI, which can effectively resist damage caused by scratching, chemical corrosion and core deformation, and significantly improve the environmental adaptability.

[0065] The integrated structure of the annular bridge arm and the pressure sensing arm eliminates the stress concentration at the connection site, improves the pressure conduction efficiency, and further enhances the mechanical bearing stability of the core. BRIEF DESCRIPTION OF DRAWINGS

[0066] In order to facilitate the understanding of those skilled in the art, the present application will be further described below in conjunction with the drawings.

[0067] Figure 1 It is a schematic diagram of a differential pressure sensor core.

[0068] Figure 2 It is a sectional view of the differential pressure sensor core.

[0069] Figure 3 It is a schematic diagram of a nanometer film structure.

[0070] Figure 4 It is a schematic diagram of a differential pressure sensor structure.

[0071] BRIEF DESCRIPTION OF DRAWINGS

[0072] 1, core mounting seat; 2, differential pressure sensor core, 3, low pressure cavity; 4, low pressure oil pipe; 5, electric signal pin; 6, filling block; 7, high pressure oil pipe; 8, plug; 9, high pressure measurement port; 10, low pressure measurement port;

[0073] 20, annular bridge arm; 21, elastic diaphragm;

[0074] 201, composite transition layer; 202, insulating layer; 203, composite strain layer; 204, pad layer; 205, protective layer;

[0075] 2000, nanometer film; 2011, transition bottom layer; 2012, transition top layer; 2031, elastic layer; 2032, precision layer; 2033, stress layer; 2051, SiO2 layer; 2052, PI layer. DETAILED DESCRIPTION

[0076] In order to facilitate the understanding of the present application, the following will be more fully and specifically described in conjunction with the preferred embodiments, but the protection scope of the present application is not limited to the following specific embodiments.

[0077] Unless otherwise defined, all the professional terms used in the following have the same meaning as generally understood by those skilled in the art. The professional terms used in this paper are only for the purpose of describing the specific embodiments and are not intended to limit the protection scope of the present application.

[0078] The raw material information used in the following examples is as follows:

[0079] The surface of the elastic diaphragm (316L stainless steel substrate, thickness 0.25mm) needs to be pretreated; the elastic diaphragm (316L stainless steel substrate) is placed in a mixed solution of ethanol and acetone (volume ratio 1:1) and ultrasonically cleaned at 100W power for 20min to remove surface oil stains; the degreased substrate is placed in a dilute hydrochloric acid solution with a mass fraction of 6% and soaked at 28°C for 8min to remove the surface oxide layer; polished to a surface roughness Ra of 0.015μm; first place the substrate in deionized water and ultrasonically clean at 80W power for 12min; then place it in anhydrous ethanol and ultrasonically clean at 80W power for 8min; place the cleaned substrate in a vacuum drying oven, vacuum degree 3×10 -2 Pa, dried at 100°C for 25min, and taken out for standby.

[0080]

Differential pressure sensor core

[0081] According to Figures 1-3 The core structure of the present application - differential pressure sensor core 2, has the following structure:

[0082] The elastic diaphragm 21 is integrally formed after welding with the annular bridge arm 20, the annular bridge arm 20 is wrapped around the upper edge of the elastic diaphragm 21, the inner side of the annular bridge arm 20 extends integrally in the radial direction to form a pressure sensing arm, the extended end of the pressure sensing arm converges in the central area of the elastic diaphragm 21, for synchronously transmitting the deformation of the elastic diaphragm 21 to the nanometer film 2000, and the nanometer film 2000 covers the upper surface of the pressure sensing arm;

[0083] Corresponding Figure 3The specific layered structure of the nanometer film 2000 from bottom to top is a composite transition layer 201, an insulation layer 202, a composite strain layer 203, a pad layer 204 and a protective layer 205 in the up-down superimposed relationship in the perspective view;

[0084] The composite transition layer 201 is divided into two sub-layers, a lower transition bottom layer 2011 and an upper transition top layer 2012;

[0085] The composite strain layer 203 is divided into three sub-layers, an elastic layer 2031, a precision layer 2032 and a stress layer 2033 from bottom to top;

[0086] The protective layer 205 is divided into two sub-layers, a bottom SiO2 layer 2051 and a top PI layer 2052.

[0087] Embodiment 1

[0088] The preparation method of the differential pressure sensor core body of the embodiment is as follows:

[0089] S1. Composite transition layer preparation

[0090] The TiNbZrMo alloy target is composed of 30% Nb, 10% Zr, 3% Mo and the balance Ti;

[0091] The TaHfTi alloy target is composed of 8% Ti, 20% Hf and the balance Ta;

[0092] The magnetron sputtering deposition method is adopted, the sputtering vacuum degree is 3×10 -3 Pa, the carrier gas is Ar, the flow rate is 30 sccm, the target-substrate distance is 10 cm, and the deposition temperature is 200°C;

[0093] The TiNbZrMo alloy target is used to deposit the transition bottom layer on the surface of the elastic diaphragm in sequence; the sputtering power is 220 W, the deposition rate is 1.0 nm / s, and a TiNbZrMo alloy layer with a thickness of 80 nm is obtained;

[0094] The TaHfTi alloy target is replaced to deposit the transition top layer, the sputtering power is 250 W, the deposition rate is 0.9 nm / s, and a TaHfTi alloy layer with a thickness of 80 nm is obtained.

[0095] S2. Insulation layer preparation

[0096] The atomic layer deposition method is adopted, the reaction cavity vacuum degree is 1×10 -3 Pa, the deposition temperature is 230°C, the precursor pulse time is 0.3 s, the purge time is 2 s, the deposition rate is 0.1 nm / cycle; trimethylaluminum (Al precursor) and deionized water, titanium tetraisopropoxide (Ti precursor) and deionized water are introduced, and the mass ratio of Al2O3 to TiO2 is controlled to be 4:1.

[0097] S3. Composite strain layer preparation

[0098] The NiCrMnTi alloy target is composed of 25% Cr, 8% Mn, 2% Ti, and the balance of Ni;

[0099] The NiCrAlMnSiWTa alloy target is composed of 15% Cr, 3% Al, 7% Mn, 0.8% Si, 1.0% W, 5.2% Ta, and the balance of Ni;

[0100] The NiCrMoV alloy target is composed of 20% Cr, 4% Mo, 2% V, and the balance of Ni;

[0101] The magnetron sputtering method is adopted, the sputtering vacuum degree is 2×10 -3 Pa, the sputtering gas is a mixed gas of Ar and N2 (volume ratio 15:1), the flow rate is 35 sccm, the target-substrate distance is 9 cm, and the deposition temperature is 250°C;

[0102] The elastic layer is deposited by using the NiCrMnTi alloy target, the sputtering power is 280 W, the deposition rate is 1.2 nm / s, and a NiCrMnTi alloy layer with a thickness of 70 nm is obtained;

[0103] The precision layer is deposited by replacing the NiCrMnTi alloy target with the NiCrAlMnSiWTa alloy target, the sputtering power is 300 W, the deposition rate is 1.0 nm / s, and a NiCrAlMnSiWTa alloy layer with a thickness of 55 nm is obtained;

[0104] The stress layer is deposited by replacing the NiCrMnTi alloy target with the NiCrMoV alloy target, the sputtering power is 290 W, the deposition rate is 1.1 nm / s, and a NiCrMoV alloy layer with a thickness of 70 nm is obtained.

[0105] S4. Pad layer preparation

[0106] The magnetron sputtering method is adopted, the Au target material is used, the sputtering vacuum degree is 2×10 -3 Pa, the sputtering gas is Ar, the flow rate is 40 sccm, the target-substrate distance is 11 cm, the deposition temperature is 150°C, the sputtering power is 230 W, the deposition rate is 1.8 nm / s, the deposition time is 556 s, and a Au layer with a thickness of 1.0 μm is obtained;

[0107] The photoresist is sprayed on the surface of the Au layer, and then pre-baked at 100°C for 45 s. Exposure treatment is carried out at 25°C, the remaining photoresist is removed with a developing solution, and then hardening treatment is carried out at 115°C, so as to prepare a Wheatstone full bridge through photoetching, and obtain a patterned pad layer; the photoresist is purchased from Shanghai Tongcheng Electronic Material Co., Ltd. RAE BP212-37S;

[0108] S5. Protective layer preparation

[0109] The chemical vapor deposition method is adopted, the reaction cavity vacuum degree is 5×10-2 Pa, deposition temperature 300℃, reaction gas is a mixed gas of SiH4, N2O and Ar (volume ratio 1:6:12), flow rate 60sccm, radio frequency power 220W, deposition rate 80nm / min, deposition time 12.5min, to obtain a SiO2 layer with a thickness of 1.0μm;

[0110] A PI glue (PI Aurum J-3472) is coated on the surface of the SiO2 layer by spin coating, the rotation speed is 4000r / min, and the coating time is 40s; the curing process is: preheating at 80℃ for 30min, keeping at 120℃ for 60min, keeping at 180℃ for 60min, keeping at 250℃ for 60min, and finally naturally cooling to room temperature, to obtain a PI layer with a thickness of 3.0μm.

[0111] S6. Post-processing

[0112] The prepared core is placed into a tube furnace, N2 is introduced for protection, the heating rate is 8℃ / min, and the temperature is raised to 350℃ and kept for 150min; then the temperature is lowered to room temperature at a rate of 4℃ / min.

[0113] Example 2

[0114] The difference between this example and Example 1 is that:

[0115] In S3, the elastic layer is deposited: a NiCrMnTi alloy target is used, the sputtering power is 250W, the deposition rate is 1.0nm / s, and the deposition thickness is 100nm;

[0116] The NiCrMnTi alloy target is composed of 30%Cr, 10%Mn, 3%Ti and the balance of Ni;

[0117] The other raw materials, steps and parameters are the same as those in Example 1.

[0118] Example 3

[0119] The difference between this example and Example 1 is that:

[0120] In S3, the precision layer is deposited: a NiCrAlMnSiWTa alloy target is used, which is composed of 20%Cr, 4%Al, 10%Mn, 1.3%Si, 0.5%W, 3.4%Ta and the balance of Ni;

[0121] The other raw materials, steps and parameters are the same as those in Example 1.

[0122] Example 4

[0123] The difference between this example and Example 1 is that:

[0124] The stress layer is deposited in S3: the NiCrMoV alloy target used has a composition of 15% Cr, 8% Mo, 5% V and the balance Ni;

[0125] The other raw materials, steps and parameters are the same as in Example 1.

[0126] Example 5

[0127] The difference between this example and Example 1 is that:

[0128] This example does not contain the step of depositing a transition top layer, but only the step of depositing a transition bottom layer;

[0129] Correspondingly, the composite transition layer only contains a transition bottom layer (TiNbZrMo alloy transition bottom layer);

[0130] The other raw materials, steps and parameters are the same as in Example 1.

[0131] Example 6

[0132] The difference between this example and Example 1 is that:

[0133] This example does not contain the step of depositing a transition top layer, but only the step of depositing a transition bottom layer;

[0134] Correspondingly, the composite transition layer only contains a transition bottom layer (TiNbZrMo alloy transition bottom layer);

[0135] The other raw materials, steps and parameters are the same as in Example 1.

[0136] Example 7

[0137] The difference between this example and Example 1 is that:

[0138] The temperature is raised at a rate of 10°C / min to 300°C, held for 180 min, and then lowered at a rate of 5°C / min;

[0139] The other raw materials, steps and parameters are the same as in Example 1.

[0140] Comparative Example 1

[0141] The difference between this comparative example and Example 1 is that:

[0142] The composite strain layer of this comparative example only contains an elastic layer and a precision layer;

[0143] Correspondingly, the step of depositing a stress layer in step S3 is not contained;

[0144] The other raw materials, steps and parameters are the same as in Example 1.

[0145] Comparative Example 2

[0146] The difference between this comparative example and Example 1 is that:

[0147] The composite strain layer of the present comparative example only contains the elastic layer and the stress layer;

[0148] Correspondingly, the step of not depositing the precision layer in step S3;

[0149] The other raw materials, steps and parameters are the same as those in Example 1.

[0150] Comparative Example 3

[0151] The difference between the present comparative example and Example 1 is that:

[0152] The composite strain layer of the present comparative example only contains the precision layer and the stress layer;

[0153] Correspondingly, the step of not depositing the elastic layer in step S3;

[0154] The other raw materials, steps and parameters are the same as those in Example 1.

[0155] Comparative Example 4

[0156] The difference between the present comparative example and Example 1 is that:

[0157] The post-processing process S6 is not included;

[0158] The other raw materials, steps and parameters are the same as those in Example 1.

[0159]

Differential pressure sensor

[0160] The differential pressure sensor composed of the differential pressure sensor core prepared in the above examples and comparative examples has the following structure: as shown in Figure 4 the differential pressure sensor includes a core mounting seat 1, a differential pressure sensor core 2, a low-pressure cavity 3, a low-pressure oil pipe 4, an electrical measurement signal needle 5, a filling block 6, a high-pressure oil pipe 7, a plug 8, a high-pressure measurement port 9, and a low-pressure measurement port 10.

[0161] The differential pressure sensor core 2 is arranged in the core mounting seat 1, and the differential pressure sensor core 2 includes an annular bridge arm 20 and an elastic diaphragm 21, the annular bridge arm 20 is fixedly connected with the elastic diaphragm 21 by welding, and a pressure sensing arm is integrated on the annular bridge arm 20, and a nano film 2000 is arranged on the upper surface of the pressure sensing arm.

[0162] A high-pressure cavity in communication with the bottom of the elastic diaphragm 21 is formed in the core mounting seat 1; the filling block 6 is arranged on the top of the annular bridge arm 20 and is sealingly connected with the low-pressure cavity 3; the differential pressure sensor core 2 separates the high-pressure cavity and the low-pressure cavity 3;

[0163] The differential pressure sensor can have a rotary body structure, one end of the high-pressure oil pipe 7 is in communication with the high-pressure cavity, and the other end is in communication with the high-pressure measurement port 9; one end of the low-pressure oil pipe 4 is in communication with the low-pressure cavity 3, and the other end is in communication with the low-pressure measurement port 10.

[0164] The cavity space between the high-pressure oil pipe 7 and the low-pressure oil pipe 4 and the high-pressure cavity and the low-pressure cavity 3 are filled with fluid; the high-pressure oil pipe 7 and the low-pressure oil pipe 4 can serve as fluid filling inlets;

[0165] One end of the electrical measurement signal lead pin 5 is electrically connected to the Wheatstone bridge, and the other end is used to output a voltage signal;

[0166] The plug 8 is installed at the end of the core mounting seat 1 and seals the end of the high-pressure oil pipe 7.

[0167] Conduction principle: high-pressure fluid conducts high pressure to the high-pressure cavity through the high-pressure measurement port 9, and then to the bottom of the elastic diaphragm 21; at the same time, low-pressure fluid conducts low pressure to the low-pressure cavity 3 through the low-pressure measurement port 10, and then to the annular bridge arm 20 through the filling block 6; the pressure sensing arm of the annular bridge arm 20 deforms, causing the nano thin film 2000 to generate a strain resistance, and then causing the output voltage of the Wheatstone bridge to change accordingly; the electrical measurement signal lead pin 5 leads the voltage signal out to an external signal acquisition device, realizing differential pressure measurement.

[0168] The differential pressure sensors prepared in the above examples and comparative examples were tested according to the following test examples.

[0169] Test Example 1 - High Differential Pressure Accuracy Test

[0170] Test environment conditions: room temperature (25°C), standard atmospheric pressure (101.325 kPa);

[0171] Accuracy test process: connect the differential pressure measurement device to the calibration table, and sequentially apply 0 kPa, 20 kPa, 40 kPa, 60 kPa, 80 kPa, and 100 kPa (rated) differential pressures, maintain each pressure point for 30 s, record the device output voltage signal, test back and forth for 3 trips, calculate the linearity, repeatability, and hysteresis errors, and calculate the measurement accuracy error according to the three properties;

[0172] Static pressure influence test process: simultaneously apply 25 MPa static pressure to the high-pressure side and the low-pressure side, and test the zero point output change under static pressure;

[0173] Calculation index: calculate repeatability ξ, hysteresis ξ, and linearity ξ according to the method in section 7.3.8 of JJG860-2015 R H L , and then calculate the comprehensive static accuracy error ξ = sqrt(ξ R 2 + ξ H 2 + ξ L 2 ​​), sqrt represents square root; static pressure influence percentage = (zero point output under 25 MPa static pressure - zero point output under atmospheric pressure) / full scale output x 100%;

[0174] The high differential static precision error directly reflects the measurement accuracy of the device under the rated and overload pressure difference, and an error of ≤±0.1% FS is an excellent level; the static pressure influence percentage is a core evaluation index, and ≤±0.1% under 25 MPa static pressure is the optimal level, ≤±1% is the standard level, and more than ±3% cannot meet the use requirements in the high static pressure scene; the test results are shown in Table 1.

[0175]

[0176] According to the results in Table 1, it needs to be noted that:

[0177] The composite transition layer of Example 5 is only a single layer (TaHfTi), and the interface bonding force with the stainless steel substrate is insufficient, micro peeling occurs under large pressure difference, and the static error significantly increases. The composite transition layer of Example 6 is only a single layer (TiNbZrMo), and the compatibility with the insulating layer is poor, and the interface stress causes precision drift.

[0178] The composite strain layer of Comparative Example 1 lacks a stress layer, and local stress concentration causes micro deformation of the film layer, the static error exceeds ±0.5%, and the stress concentration aggravates the zero point offset under static pressure. The composite strain layer of Comparative Example 2 lacks a precision layer, and there is no special low-drift sensing unit, the static error significantly increases, the elastic layer is directly in contact with the stress layer, and the stability under static pressure is poor. The composite strain layer of Comparative Example 3 lacks an elastic layer, and cannot absorb the overload pressure, the precision layer directly bears the impact, the static error exceeds the standard too much, and the stress of the precision layer under static pressure exceeds the elastic range.

[0179] Test Example 2 - Alternating Pressure Difference Fatigue Stability Test

[0180] Test equipment: alternating pressure fatigue test bench, data acquisition instrument;

[0181] Test conditions: alternating pressure difference range 0-200 kPa, fluctuation frequency 10 Hz, room temperature 25°C;

[0182] Test process: divided into two groups, the first group applies 0-100 kPa differential pressure, and the second group applies 0-200 kPa differential pressure, starts the test bench, applies alternating pressure difference to the sensor, accumulates 500,000 cycles, and tests the static precision error under the two states before and after the cycle;

[0183] Calculation index: precision attenuation rate after fatigue = (precision error after cycle - precision error before cycle) / precision error before cycle x 100%; the test results are shown in Table 2.

[0184]

[0185] According to the results of Table 2, it is noted that:

[0186] Example 5 has weak interface bonding of the single-layer transition layer, micro-peeling occurs in alternating cycles, and precision attenuation is serious; interlayer damage accumulates, and the attenuation rate exceeds 5% under 200 kPa overload, which does not meet the long-term use requirements. Example 6 has poor compatibility between the single-layer transition layer and the insulating layer, interface wear is intensified in fatigue cycles, and the attenuation rate is also higher.

[0187] Comparative Example 1 lacks a stress layer, local stress concentration in alternating cycles leads to film layer cracking, and precision is greatly attenuated; under overload conditions, cracks propagate, and the attenuation rate exceeds 8%, resulting in core performance failure. Comparative Example 2 lacks a precision layer, and there is no stable sensing unit, signal drift accumulates in fatigue cycles; the function of the elastic layer and the stress layer conflicts, damage is intensified under overload, and the attenuation rate is seriously out of standard. Comparative Example 3 lacks an elastic layer, and the precision layer directly bears alternating impact, with high risk of film fatigue fracture; under overload conditions, precision stability is completely lost, and the attenuation rate exceeds 11%.

[0188] Unless otherwise specifically indicated, various materials, reagents, instruments and equipment and the like used in the present application can be purchased from the market or can be 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 description is only a specific embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included within the scope of protection of the present application.

Claims

1. A differential pressure sensor core, comprising a nanofilm, characterized in that, The nanofilm consists of, from bottom to top, a composite transition layer, an insulating layer, a composite strain layer, a pad layer, and a protective layer. The composite strain layer consists of an elastic layer, a precision layer, and a stress layer from bottom to top. The elastic layer is a NiCrMnTi alloy layer, the precision layer is a NiCrAlMnSiWTa alloy layer, and the stress layer is a NiCrMoV alloy layer. The composite transition layer is a two-layer structure consisting of a transition bottom layer and a transition top layer. The transition bottom layer is a TiNbZrMo alloy layer, and the transition top layer is a TaHfTi alloy layer.

2. The differential pressure sensor core as described in claim 1, characterized in that, The mass composition of the TiNbZrMo alloy layer is: 25%~35%Nb, 7%~13%Zr, 2%~5%Mo and balance Ti; And / or, the mass fraction of the TaHfTi alloy layer is: 15%~25%Hf, 5%~10%Ti and balance Ta; And / or, the thickness of the transition layer is 40~130nm; And / or, the thickness of the transition top layer is 40~120nm.

3. The differential pressure sensor core as described in claim 1, characterized in that, The insulating layer is an Al2O3-TiO2 layer; And / or, the thickness of the insulating layer is 0.5~3μm.

4. The differential pressure sensor core as described in claim 1, characterized in that, The mass composition of the NiCrMnTi alloy layer is: 20%~30%Cr, 5%~10%Mn, 1%~3%Ti, and the balance Ni; And / or, the mass composition of the NiCrAlMnSiWTa alloy layer is: 12%~18%Cr, 2%~4%Al, 6%~9%Mn, 0.6%~0.9%Si, 0.8%~1.2%W, 4.5%~5.5%Ta and the balance Ni; And / or, the mass composition of the NiCrMoV alloy layer is: 15%~25%Cr, 3%~6%Mo, 1%~3%V and the balance Ni; And / or, the thickness of the elastic layer is 40~100nm; And / or, the thickness of the precision layer is 30~80nm; And / or, the thickness of the stress layer is 30~100nm.

5. The differential pressure sensor core as described in claim 1, characterized in that, The protective layer consists of a bottom SiO2 layer and a top PI layer.

6. The differential pressure sensor core as described in claim 5, characterized in that, The thickness of the SiO2 layer is 0.5~5μm; And / or, the thickness of the PI layer is 1.5~5μm; And / or, the material of the pad layer is Au; And / or, the thickness of the pad layer is 0.8~3μm.

7. The differential pressure sensor core as described in any one of claims 1, characterized in that, The differential pressure sensor core includes an elastic diaphragm, and an annular bridge arm is disposed on the surface of the elastic diaphragm. The annular bridge arm also includes a pressure-sensing arm, which is an integral part of the annular bridge arm. The pressure deformation borne by the annular bridge arm is transmitted to the nanofilm through the pressure-sensing arm, and the nanofilm is disposed on the upper surface of the pressure-sensing arm.

8. The differential pressure sensor core as described in claim 7, characterized in that, The elastic diaphragm is a stainless steel substrate, and its material is 17-4PH stainless steel, 17-7PH stainless steel, 316 stainless steel, 316L stainless steel, 304 stainless steel, 304L stainless steel or 15-5PH stainless steel. And / or, the thickness of the elastic diaphragm is 0.1~0.3mm.

9. The method for preparing the differential pressure sensor core according to any one of claims 1 to 8, characterized in that, Includes the following steps: S1. A composite transition layer is formed by sequentially depositing a transition underlayer and a transition toplayer on the surface of an elastic diaphragm using magnetron sputtering. S2. An insulating layer is deposited on the surface of the composite transition layer using atomic layer deposition (ALD). S3. An elastic layer, a precision layer, and a stress layer are sequentially deposited on the surface of the insulating layer using magnetron sputtering to form a composite strain layer; S4. An Au layer is deposited on the surface of the composite strain layer by magnetron sputtering, and the pad layer is patterned by photolithography. S5. First, SiO2 layer is deposited in the exposed areas of the pad layer and composite strain layer using chemical vapor deposition. Then, PI adhesive is coated and cured to obtain a protective layer. S6. Anneal the prepared core to obtain the differential pressure sensor core.

10. The method for preparing the differential pressure sensor core as described in claim 9, characterized in that, At least one of the following conditions (1) to (19) must be met: (1) Before S1, the elastic diaphragm needs to be pretreated, namely, degreasing, pickling, polishing, cleaning and drying are performed in sequence; (2) In S1, the target materials for the magnetron sputtering transition bottom layer and the transition top layer are TiNbZrMo alloy target and TaHfTi alloy target, respectively; (3) In S1, the carrier gas for magnetron sputtering is Ar, and the carrier gas flow rate is 20~40 sccm; (4) In S1, the deposition temperature of the magnetron sputtering is 150~250℃; (5) In S1, the power of the magnetron sputtering is 150~300W; (6) In S2, the atomic layer deposition process is as follows: Al precursor, Ti precursor and H2O are deposited at a rate of 0.2~0.5 nm / cycle; (7) In S2, the deposition temperature of the atomic layer deposition is 180~280℃; (8) In S3, the target materials for the magnetron sputtering elastic layer, precision layer and stress layer are NiCrMnTi alloy target, NiCrAlMnSiWTa alloy target and NiCrMoV alloy target, respectively. (9) In S3, the carrier gas for magnetron sputtering is a mixture of Ar and N2, with a volume ratio of Ar to N2 of 10:1 to 20:1 and a carrier flow rate of 25 to 45 sccm. (10) In S3, the deposition temperature of the magnetron sputtering is 200~300℃; (11) In S3, the power of the magnetron sputtering is 200~350W; (12) In S4, the carrier gas for magnetron sputtering is Ar, and the carrier gas flow rate is 30~50 sccm; (13) In S4, the deposition temperature of the magnetron sputtering is 100~200℃; (14) In S4, the power of the magnetron sputtering is 180~280W; (15) In S4, the photolithography development is a process of pre-baking after spraying photoresist, followed by exposure treatment, removal of residual agent, and then hardening treatment. (16) In S5, the chemical vapor deposition process is as follows: a mixed gas of SiH4, N2O and Ar with a volume ratio of 1:5:10~1:8:15 and a mixed gas flow rate of 40~80 sccm is deposited at a speed of 50~100 nm / min. (17) In S5, the PI adhesive coating process is as follows: coating for 30 to 60 seconds at a rotation speed of 3000 to 5000 r / min; (18) In S5, the curing process is as follows: first, preheat at 70~90℃ for 20~40min, then keep warm at 110~130℃, 170~190℃ and 220~260℃ for 50~70min each, and finally cool naturally to room temperature; (19) In S6, the annealing process is: under the protection of inert gas, the temperature is kept at 300~400℃ for 120~180min.

11. A differential pressure sensor, characterized in that, Includes the differential pressure sensor core as described in any one of claims 1 to 8.

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