Pickling process of ultra-thin invar sheet

Abstract

The present application relates to a kind of pickling process of ultra-thin invar alloy plate, belong to the field of metal material surface treatment, at least one of the problems in the prior art, such as incomplete removal of oxide layer, over-corrosion affecting strip quality and performance, and low pickling efficiency, is solved when the pickling process is applied to ultra-thin invar alloy plate.A kind of pickling process of ultra-thin invar alloy plate, comprising the following steps: surface pretreatment, oil grinding treatment, rinsing after oil grinding, pickling treatment, and post-processing.The present application realizes the balance of efficient removal of oxide layer and matrix protection, and improves pickling efficiency.

Description

Technical Field

[0001] This invention relates to the field of surface treatment technology for metal materials, and in particular to an acid pickling process for ultra-thin Invar alloy plates. Background Technology

[0002] In the electronics industry, ultra-thin Invar alloy sheets are key core substrates for manufacturing products such as integrated circuit lead frames, thermostats, precision resistors, and precision metal masks for OLED displays. The requirements for dimensional stability and surface quality are extremely stringent.

[0003] However, after heat treatment such as hot rolling, a dense oxide layer forms on the surface of ultra-thin Invar alloy sheets. Thorough removal of this oxide layer is a prerequisite for its electronic applications, but this is precisely the serious challenge faced by existing pickling processes. Because the solution system and process parameters of traditional pickling are difficult to adapt to the characteristics of ultra-thin Invar alloy strips, they often fall into a dilemma of "insufficient removal" and "over-corrosion": insufficient pickling leads to oxide layer residue; while extending the treatment time or increasing the concentration to improve the cleaning effect easily leads to over-corrosion of the substrate and dissolution of nickel, which not only damages the integrity of the material surface but also harms its core chemical composition and crystal structure stability.

[0004] Therefore, developing an efficient and safe pickling process that can precisely remove the oxide layer while ensuring no damage to the substrate has become a pressing technical challenge to promote ultra-thin Invar alloys to higher-end electronic applications. Summary of the Invention

[0005] In view of the above analysis, the present invention aims to provide a pickling process for ultra-thin Invar alloy sheets, in order to solve at least one of the following problems when the pickling process in the prior art is applied to ultra-thin Invar alloy sheets: incomplete removal of oxide layer, excessive corrosion affecting the quality and performance of strip, and low pickling efficiency.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] This invention provides an acid pickling process for ultra-thin Invar alloy sheets, comprising the following steps:

[0008] Surface pretreatment, oil grinding, post-oil grinding rinsing, pickling, and post-treatment;

[0009] The pickling process uses a pickling solution containing hydrochloric acid and nitric acid;

[0010] The post-processing includes washing, passivation, and drying.

[0011] Furthermore, in the oil milling process, the grinding oil used comprises mineral oil and extreme pressure agent, wherein the mass ratio of mineral oil to extreme pressure agent is (8-12):1; and / or,

[0012] The oil mill pressure is 0.1-0.3 MPa; and / or,

[0013] The grinding speed is 1-3 m / min; and / or,

[0014] The polishing process is repeated 1-2 times.

[0015] Furthermore, the oil milling process employs a silicon carbide grinding head with a particle size of 800-1200 mesh; and / or,

[0016] During the polishing process, the polishing oil is replenished with a spray rate of 5-10 L / h.

[0017] Further, in the pickling process, the pickling solution is a mixed aqueous solution of hydrochloric acid and nitric acid, comprising 7%-18% hydrochloric acid and 0.5%-3.0% nitric acid by mass, with the balance being water; and / or,

[0018] Pickling temperature is 30-50℃; and / or,

[0019] Pickling time is 5-15 minutes.

[0020] Furthermore, in the surface pretreatment, the degreasing agent used comprises sodium hydroxide, sodium carbonate, and a nonionic surfactant, wherein the mass ratio of sodium hydroxide, sodium carbonate, and nonionic surfactant is (4-6):(2-4):(1-3); and / or,

[0021] The working mass concentration of the degreasing agent is 8%-15%.

[0022] Furthermore, the water washing in the post-treatment process uses deionized water with a conductivity ≤ 5 μS / cm; and / or,

[0023] The washing temperature is 25-35℃; and / or,

[0024] After washing, the pH value of the board surface is 6-7, and the residual acid content on the surface is ≤0.01g / m². 2 .

[0025] Furthermore, in the passivation process, the passivation solution used is an aqueous solution of trivalent chromium, wherein the trivalent chromium aqueous solution contains Cr 3+ The molar concentration is 0.2–0.8 mol / L; and / or,

[0026] The passivation temperature is 40-60℃; and / or,

[0027] The passivation time is 2-5 minutes.

[0028] Furthermore, the passivation process includes a passivation solution cleaning step after the passivation; the process involves rinsing with deionized water at a pressure of 0.2-0.4 MPa, with the water flow rate controlled at 0.4-0.7 m / s.

[0029] Furthermore, the drying temperature is 60-80°C; and / or,

[0030] The air velocity during the drying process is 1-1.5 m / s.

[0031] Further, after the drying process, the obtained ultrathin Invar alloy sheet is evaluated, including:

[0032] The surface roughness of the plate is tested, and the acceptable standard is Ra≤0.2μm; and / or,

[0033] The oxide layer removal rate of the board material is tested, and the pass standard is an oxide layer removal rate ≥ 98%; and / or,

[0034] The integrity of the crystal structure of the plate is tested, and the pass standard is the absence of lattice distortion or phase transition.

[0035] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0036] (1) This invention achieves a balance between efficient oxide layer removal and substrate protection through a synergistic process system of "oil grinding + mixed pickling". The process first removes the loose oxide layer on the surface through an oil grinding step, significantly reducing the burden on subsequent pickling; then, a hydrochloric acid-nitric acid mixed acid system is used to achieve targeted removal of the dense oxide layer, overcoming the bottleneck of traditional pickling which easily leads to over-corrosion and excessive surface roughness of the ultra-thin Invar alloy substrate. This staged treatment strategy ensures the complete removal of the oxide layer on the surface of the ultra-thin Invar alloy sheet, and effectively avoids the over-corrosion problem common in traditional single pickling processes by shortening the contact time between the strong acid and the substrate and reducing the corrosion intensity. This helps ensure the surface integrity and compositional stability of the ultra-thin Invar alloy sheet, guaranteeing the quality and performance of the sheet.

[0037] (2) The present invention achieves efficient removal of oxide layer by first oil grinding to remove the loose outer oxide layer and then acid washing to remove the dense inner oxide layer. Compared with the traditional single mode, it improves the acid washing efficiency.

[0038] (3) The pickling method provided by the present invention results in an ultra-thin Invar alloy plate with a surface roughness Ra≤0.2μm; an oxide layer removal rate≥98%; good crystal structure integrity; and XRD test shows that there is no lattice distortion or phase transformation.

[0039] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0040] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0041] Figure 1 A schematic diagram of the pickling process for an ultra-thin Invar alloy sheet provided in an embodiment of the present invention;

[0042] Figure 2 This is a comparison chart of the roughness test results for the example and the comparative example;

[0043] Figure 3 This is a comparison chart of the oxide layer removal rates of the examples and comparative examples;

[0044] Figure 4 Macroscopic images of ultra-thin Invar alloy sheets obtained by the pickling process provided in this embodiment of the invention;

[0045] Figure 5 The EBSD (electron backscatter diffraction) analysis results of the ultrathin Invar alloy plate obtained by the pickling process provided in the embodiment of the present invention are shown in (a) KAM diagram (intragranular orientation difference diagram) and (b) Euler diagram (grain orientation distribution diagram).

[0046] Figure 6 The EBSD (electron backscatter diffraction) analysis results of the ultrathin Invar alloy plate obtained by the pickling process provided in Comparative Example 2-1 are shown in (a) KAM diagram (internal orientation difference diagram) and (b) Euler diagram (grain orientation distribution diagram).

[0047] Figure 7 The electron microscopy analysis results of the ultrathin Invar alloy plate obtained after "oil grinding treatment + pickling treatment" in the pickling process provided in the embodiment of the present invention are shown in (a) selected area electron diffraction pattern and (b) electron microscopy morphology image.

[0048] Figure 8 The electron microscopy analysis results of the ultrathin Invar alloy plate obtained after "oil grinding" in the pickling process provided in the embodiment of the present invention are shown in (a) selected area electron diffraction pattern and (b) electron microscopy morphology image.

[0049] Figure 9SEM image of the ultrathin Invar alloy sheet obtained by the pickling process provided in this embodiment of the invention;

[0050] Figure 10 SEM image of the ultra-thin Invar alloy sheet obtained by the pickling process provided in Comparative Example 5-1. Detailed Implementation

[0051] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0052] Traditional or existing pickling processes for alloy plates generally employ a single linear process of "degreasing → pickling → washing → drying." The pickling solution is mostly composed of high-concentration single strong acid, relying on its strong corrosiveness to quickly dissolve the oxide layer. This method is highly aggressive, difficult to control precisely, and easily leads to problems such as over-corrosion of the substrate, hydrogen embrittlement, and selective dissolution of alloying elements (for Invar alloys, the dissolution of nickel will destroy its stable low expansion characteristics). At the same time, existing processes are mainly designed for plates of conventional thickness, and factors such as solution impact and thermal stress can easily cause irreversible dimensional and shape defects such as warping, deformation, and scratches to ultra-thin Invar alloy plates.

[0053] To address the aforementioned issues, this invention proposes a novel pickling process tailored to the characteristics of ultra-thin Invar alloy sheets. By organically combining physical grinding and chemical etching, it aims to solve the technical challenges of over-etching, material deformation, and uncontrollable surface quality inherent in traditional processes, providing a reliable surface treatment solution for the electronic-grade applications of ultra-thin Invar alloy sheets.

[0054] This invention provides an acid pickling process for ultra-thin Invar alloy sheets, comprising the following steps:

[0055] Surface pretreatment, oil grinding, post-oil grinding rinsing, pickling, and post-treatment;

[0056] The pickling process uses a pickling solution containing hydrochloric acid and nitric acid;

[0057] The post-processing includes washing, passivation, and drying.

[0058] Compared with existing technologies, this invention achieves a balance between efficient oxide layer removal and substrate protection through a synergistic process system of "oil grinding + mixed pickling". The process first removes the loose oxide layer on the surface through oil grinding, significantly reducing the burden on subsequent pickling. Then, a hydrochloric acid-nitric acid mixed acid system is used to target and remove the dense oxide layer, overcoming the bottleneck of traditional pickling methods that easily lead to over-corrosion and excessive surface roughness of the ultra-thin Invar alloy substrate. This staged treatment strategy ensures the complete removal of the oxide layer on the surface of the ultra-thin Invar alloy sheet, and effectively avoids the over-corrosion problem common in traditional single pickling processes by shortening the contact time between the strong acid and the substrate and reducing the corrosion intensity. This helps ensure the surface integrity and compositional stability of the ultra-thin Invar alloy sheet, guaranteeing the quality and performance of the sheet.

[0059] This invention achieves efficient removal of the oxide layer by first oil grinding to remove the loose outer oxide layer and then acid washing to remove the dense inner oxide layer. Compared with the traditional single mode, it improves the acid washing efficiency.

[0060] Specifically, the oil polishing process includes polishing the surface of the pretreated ultra-thin Invar alloy sheet using oil polishing equipment.

[0061] In order to better achieve the dual goals of efficient removal of the oxide layer (loose outer layer) and protection of the substrate, this invention optimizes and coordinates the grinding oil composition and oil grinding process parameters in the oil grinding process.

[0062] Specifically, in the oil milling process, the oil milling tension control range is 20-30KN. For example, the oil milling tension is 20KN, 22KN, 24KN, 25KN, 26KN, 27KN, ​​28KN, 29KN, or 30KN.

[0063] Preferably, the oil mill tension is 24-28KN.

[0064] Specifically, the oil mill tension control method is as follows: a constant tension closed-loop control system is adopted, which monitors the tension change of the plate in real time through a tension sensor to ensure that the tension fluctuation range is ≤±2KN.

[0065] Specifically, in the oil milling process, the grinding oil used contains mineral oil and extreme pressure agent, and the mass ratio of mineral oil to extreme pressure agent is (8-12):1.

[0066] For example, the mass ratio of the mineral oil to the extreme pressure agent is 8:1, 9:1, 9.2:1, 9.5:1, 9.8:1, 10:1, 10.2:1, 10.5:1, 10.8:1, 11:1, or 12:1; preferably (9 to 11):1.

[0067] For example, the mineral oil is selected from one or a combination of several of naphthenic mineral oil, intermediate mineral oil, paraffinic mineral oil, and light white oil; preferably, it is paraffinic mineral oil.

[0068] Preferably, the kinematic viscosity (40°C) of the mineral oil is 10–30 mm. 2 / s, viscosity index ≥95; flash point ≥150℃; pour point ≤-15℃; moisture ≤0.03ppm; acid value ≤0.05mg KOH / g.

[0069] For example, the naphthenic mineral oil includes Kunlun KN4010 naphthenic base oil, Great Wall 45# naphthenic base oil, and PetroChina Karamay KN4050 naphthenic base oil.

[0070] For example, the intermediate base mineral oil includes Sinopec 150SN intermediate base oil, CNOOC HVI250 intermediate base oil, and Kunlun KL-200 intermediate lubricating oil base oil.

[0071] For example, the paraffinic mineral oil includes Kunlun SN150 paraffinic base oil, Great Wall L-AN46 paraffinic system oil, and Sinopec Maoming 100SN paraffinic process oil.

[0072] For example, the light white oil includes Kunlun L-10 light white oil, Great Wall HC-15 light white oil, and Sinopec Jinling 10# industrial grade light white oil.

[0073] For example, the extreme pressure agent is selected from one or more combinations of isobutylene sulfide, dibenzyl disulfide, phosphate ester amine salt, and borate ester; preferably isobutylene sulfide.

[0074] For example, isobutylene sulfide has R-CH2-S X The structure of -CH2-R (R is isobutyl, x is usually 1-4, preferably x = 2 or 3).

[0075] For example, the phosphate ester amine salt is selected from one or more of tricresyl phosphate amine salt T306, triphenyl phosphate amine salt T307, and dioctyl phosphate amine salt T309.

[0076] For example, the borate ester is selected from one or more of tributyl borate T361, triisooctyl borate T362, and dipropyl borate T363.

[0077] Specifically, the oil mill pressure is 0.1-0.3 MPa. For example, the oil mill pressure is 0.1 MPa, 0.15 MPa, 0.18 MPa, 0.2 MPa, 0.25 MPa, or 0.3 MPa; preferably 0.15-0.2 MPa.

[0078] Specifically, the grinding speed is 1-3 m / min. For example, the grinding speed is 1.0 m / min, 1.5 m / min, 1.8 m / min, 2.0 m / min, 2.2 m / min, 2.5 m / min, or 3.0 m / min; preferably 1.5 to 2.5 m / min.

[0079] Specifically, the polishing process is repeated 1-2 times.

[0080] It should be noted that the specific ratio of grinding oil components forms a stable lubricating protective film during the grinding process, effectively reducing the coefficient of friction and significantly minimizing surface phase transformation damage caused by frictional overheating, while maintaining the integrity of the matrix grain structure. By precisely controlling key parameters such as grinding pressure and grinding speed, a processing environment with uniform stress distribution is established, suppressing local stress concentration and keeping the warpage deformation of ultra-thin sheets within the allowable range of the process, ensuring that the product has excellent flatness and dimensional stability. Through the synergistic control of the grinding oil components and grinding process parameters, the dual goals of efficient removal of the oxide layer (loose outer layer) and matrix protection are achieved.

[0081] To achieve a better balance between the efficiency of removing the loose oxide layer on the surface of Invar alloy plates and the protection of the substrate, this invention optimizes and coordinates the material, particle size, and spraying parameters of the grinding head.

[0082] Specifically, the oil grinding process uses a silicon carbide grinding head with a particle size of 800-1200 mesh.

[0083] For example, the particle size of the silicon carbide grinding head is 800 mesh, 900 mesh, 1000 mesh, 1100 mesh, or 1200 mesh; preferably 1000 to 1200 mesh.

[0084] Specifically, the polishing oil is replenished during the polishing process with a spray rate of 5-10 L / h.

[0085] For example, the spraying rate is 5L / h, 6L / h, 6.5L / h, 7L / h, 7.5L / h, 8L / h, 9L / h, or 10L / h; preferably 6 to 8L / h.

[0086] It should be noted that by using a silicon carbide grinding head, compared to a traditional rigid grinding head, the elastic modulus of the silicon carbide grinding head is reduced, which can avoid extrusion deformation of ultra-thin plates. By controlling the grinding head particle size to precisely match the oxide layer thickness, it can be ensured that it only acts on the loose oxide outer layer during processing and does not touch the substrate surface, thus avoiding extrusion deformation of ultra-thin plates. During the grinding process, the grinding oil is replenished by spraying, and by controlling the spray volume, the lubrication and cooling effect of the grinding oil can be guaranteed, while avoiding oil residue affecting the subsequent pickling efficiency. Through the coordinated control of the grinding head material, particle size, and spray parameters, an optimized balance between cleaning efficiency and substrate protection is achieved.

[0087] Specifically, after the oil grinding process, the process also includes: post-oil grinding rinsing to remove residues from the surface of the board, including residual grinding oil and substances peeled off from the surface of the board by the oil grinding process, such as debris from the loose oxide layer.

[0088] It is understood that the "loose oxide layer" mentioned in this invention refers to an oxide layer with a porosity ≥25% and a microhardness of 200-350 HV. In some embodiments, the thickness of the loose oxide layer on the surface of the ultra-thin Invar alloy sheet ranges from 0.2 to 1.5 μm.

[0089] Specifically, the post-oil mill rinsing is performed using deionized water at a pressure of 0.6-0.9 MPa; the rinsing time is 2-4 minutes; and the rinsing water flow rate is 1.0-1.5 m / s.

[0090] Preferably, the post-oil grinding rinsing uses symmetrical multi-hole nozzles to rinse the surface of the Invar alloy sheet after oil grinding.

[0091] For example, the orifice diameter of the multi-hole nozzle is 0.3-1.0 mm; the orifices are uniformly distributed on the nozzle, and the orifice density can be 10-30 orifices / dm³. 2 The angle between the spray axis of the upper and lower nozzles and the normal to the surface of the board can be independently set from 10° to 45°; preferably from 10° to 30°.

[0092] It should be noted that, in order to evaluate the effect of oil grinding, SEM was used to observe the cross-section of the plate before and after oil grinding, measure the percentage difference in oxide layer thickness, and calculate the loose oxide layer removal rate. The pre-treatment (mainly oil grinding) provided in this embodiment of the invention can achieve a loose oxide layer removal rate of ≥98%; Loose oxide layer removal rate = ((Oxide layer thickness before oil grinding - Residual oxide layer thickness after oil grinding) / Loose oxide layer thickness before oil grinding) × 100%.

[0093] Specifically, the pickling process includes immersing the ultra-thin Invar alloy sheet in a customized pickling solution to achieve targeted removal of the dense oxide layer, thus overcoming the bottleneck of traditional pickling which easily leads to over-corrosion of the ultra-thin Invar alloy substrate and excessive surface roughness.

[0094] It is understood that the "dense oxide layer" mentioned in this invention refers to an oxide layer with a porosity ≤8% and a microhardness of 450-650 HV. In some embodiments, the thickness of the dense oxide layer on the surface of the ultra-thin Invar alloy sheet is 0.05-0.5 μm.

[0095] Specifically, the pickling solution is a mixed aqueous solution of hydrochloric acid and nitric acid. Based on the total mass of the pickling solution, the pickling solution contains 7%-18% hydrochloric acid and 0.5%-3.0% nitric acid by mass, with the balance being water.

[0096] Specifically, in the pickling solution, the mass ratio of hydrochloric acid to nitric acid is 2.3:1 to 36:1.

[0097] For example, the pickling solution contains hydrochloric acid at a mass percentage of 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, or 18%; preferably 8%-16%.

[0098] For example, the pickling solution contains 0.5%, 0.7%, 1.0%, 1.2%, 1.5%, 1.7%, 2.0%, 2.2%, 2.5%, 2.7%, or 3.0% by mass; preferably 1.0%-2.5%.

[0099] Preferably, in the pickling solution, the mass ratio of hydrochloric acid to nitric acid is (4:1) to (20:1).

[0100] For example, in the pickling solution, the mass ratio of hydrochloric acid to nitric acid is 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1, 25:1, 30:1, or 33:1. Further, the mass ratio of hydrochloric acid to nitric acid is from (4:1) to (13:1).

[0101] In some preferred embodiments, the pickling solution contains 9%-15% hydrochloric acid and 1.2%-2.3% nitric acid by mass, with the balance being water, based on the total mass of the pickling solution.

[0102] Specifically, in the pickling process, the pickling solution is prepared by mixing a hydrochloric acid solution with a concentration of 10wt.%-20wt.% and a nitric acid solution with a concentration of 5wt.%-10wt.% at a volume ratio of (3-5):1.

[0103] For example, in the preparation of the pickling solution, the concentration of the hydrochloric acid solution is 10 wt.%, 12 wt.%, 14 wt.%, 16 wt.%, 18 wt.%, or 20 wt.%.

[0104] For example, in the preparation of the pickling solution, the concentration of the nitric acid solution is 5 wt.%, 6 wt.%, 7 wt.%, 8 wt.%, 9 wt.%, or 10 wt.%.

[0105] For example, the volume ratio of the hydrochloric acid solution to the nitric acid solution is 3:1, 3.5:1, 4:1, 4.5:1, or 5:1.

[0106] Preferably, the pickling solution is prepared by mixing a hydrochloric acid solution with a concentration of 12wt.%-18wt.% and a nitric acid solution with a concentration of 7wt.%-9wt.% at a volume ratio of (3.5-4.5):1.

[0107] Specifically, the pickling temperature is 30-50℃; for example, the pickling temperature is 30℃, 35℃, 40℃, 45℃, or 50℃; preferably 35-45℃.

[0108] Specifically, the pickling time is 5-15 minutes. For example, the pickling time is 5 minutes, 7 minutes, 9 minutes, 11 minutes, 13 minutes, or 15 minutes; preferably 7 to 11 minutes.

[0109] For example, the pickling temperature fluctuation is maintained at ≤±2℃ by boiler steam heating. During pickling, slight shaking is incorporated to promote the removal of reaction products. This slight shaking is achieved by a mechanical device driving the pickling tank to perform periodic reciprocating motion; specifically, the parameters of this periodic reciprocating motion are controlled as follows: amplitude 8-12cm, frequency 1-1.5Hz (i.e., 60-90 reciprocations per minute). It can be understood that the pickling tank (or the frame in which the sheet is placed) performs periodic reciprocating motion back and forth (or left and right) in the horizontal direction. Preferably, the periodic reciprocating motion is performed back and forth (along the length of the strip) in the horizontal direction.

[0110] It should be noted that by employing a hydrochloric acid-nitric acid mixed acid system and controlling process parameters, efficient removal of the dense oxide layer and reliable protection of the substrate material were achieved. Specifically, the scientifically proportioned hydrochloric acid-nitric acid mixed acid system maintained the hydrogen ion concentration within a suitable low range. This concentration range ensured sufficient dissolution kinetics for the oxide layer, guaranteeing efficient removal of the dense oxide layer, while also reducing the substrate corrosion rate, thus meeting the sensitive requirements of ultra-thin Invar alloy plates for corrosion depth. Hydrochloric acid penetrates and peels off the oxide layer, while nitric acid, through its oxidizing properties, forms a nanoscale protective film on the substrate surface. The synergistic effect of these two components establishes an effective corrosion inhibition mechanism. Controlling the pickling temperature prevents excessive temperature from exposing the substrate grains. For example, boiler steam heating maintains temperature fluctuations ≤ ±2℃, effectively preventing reaction rate instability caused by temperature fluctuations. Controlling the pickling time ensures both complete dissolution of the dense oxide layer and prevents substrate damage caused by excessively long processing times. By synergistically controlling pickling temperature and time, an optimized balance is achieved between efficient removal of the oxide layer and complete protection of the substrate. While ensuring thorough removal of the oxide layer, the substrate loss is strictly controlled to within ≤1.5μm.

[0111] It should be noted that, in order to evaluate the effect of the pickling treatment provided by the present invention, a high-precision thickness gauge is used to measure the difference in plate thickness before and after pickling, and to determine the corrosion depth of the plate substrate after pickling. The pickling treatment provided in the embodiment of the present invention achieves a substrate corrosion depth ≤0.6μm.

[0112] Specifically, the surface pretreatment includes: using an oil remover suitable for Invar alloy material to clean the surface of the ultra-thin Invar alloy sheet to be treated, removing oil and dust adhering to the surface. The oil remover has the characteristics of being non-corrosive to the substrate and having low residue, thus avoiding damage to the surface microstructure of the ultra-thin Invar alloy sheet.

[0113] Specifically, in the surface pretreatment, the degreasing agent used includes sodium hydroxide, sodium carbonate and nonionic surfactant, and the mass ratio of sodium hydroxide, sodium carbonate and nonionic surfactant is (4-6):(2-4):(1-3).

[0114] Specifically, in the surface pretreatment, the temperature of the degreasing agent used is 40-55°C, and the surface pretreatment time is 8-10 minutes.

[0115] For example, the temperature of the degreasing agent used is 40°C, 42°C, 45°C, 47°C, 50°C, 52°C, or 55°C; preferably 45°C to 50°C.

[0116] For example, the surface pretreatment time is 8.0 min, 8.5 min, 8.7 min, 9.0 min, 9.2 min, 9.5 min, or 10.0 min; preferably 8.5 to 9.5 min.

[0117] For example, the degreasing agent used comprises sodium hydroxide, sodium carbonate and a nonionic surfactant, with the remainder being water; the mass ratio of the sodium hydroxide, sodium carbonate and the nonionic surfactant is (4, 4.5, 4.8, 5, 5.2, 5.5, 6): (2, 2.5, 2.8, 3, 3.2, 3.5, 4): (1, 1.5, 1.8, 2, 2.2, 2.5, 3).

[0118] Preferably, the degreasing agent used comprises sodium hydroxide, sodium carbonate and a nonionic surfactant, wherein the mass ratio of sodium hydroxide, sodium carbonate and nonionic surfactant is (4.5-5.5):(2.5-3.5):(1.5-2.5).

[0119] For example, the nonionic surfactant is selected from one or more combinations of fatty alcohol polyoxyethylene ether, polyoxyethylene castor oil, alkyl glycoside, and alkylphenol polyoxyethylene ether; preferably fatty alcohol polyoxyethylene ether.

[0120] For example, the fatty alcohol polyoxyethylene ether is selected from one or more of AEO-7 (fatty alcohol polyoxyethylene ether-7), AEO-9 (fatty alcohol polyoxyethylene ether-9), and AEO-15 (fatty alcohol polyoxyethylene ether-15). For example, the carbon chain length of the fatty alcohol is C12-C14. The number AEO-15 represents an average of 15 ethylene oxide (EO) units added to each fatty alcohol molecule.

[0121] For example, the polyoxyethylene castor oil is selected from one or more of EL-20 (polyoxyethylene (20) castor oil), EL-40 (polyoxyethylene (40) castor oil), and EL-60 (polyoxyethylene (60) castor oil).

[0122] For example, the alkyl glycoside is selected from one or more of APG0810 (C8-C10 alkyl glycoside), APG1214 (C12-C14 alkyl glycoside), and APG0814 (C8-C14 alkyl glycoside).

[0123] For example, the alkylphenol polyoxyethylene ether is selected from one or more of OP-10 (octylphenol polyoxyethylene ether-10), NP-10 (nonylphenol polyoxyethylene ether-10), and DP-12 (dodecylphenol polyoxyethylene ether-12). Specifically, the working mass concentration of the degreasing agent is 8%-15%.

[0124] For example, the working mass concentration of the degreasing agent is 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15%; preferably 9% to 12%.

[0125] It should be noted that by optimizing the component ratio and process parameters of the degreasing agent, efficient removal of surface contaminants and reliable protection of the substrate material are achieved. The degreasing agent maintains good degreasing efficiency while avoiding corrosive damage to the surface of the Invar alloy sheet. Compared to traditional degreasing processes, this solution effectively prevents edge corrosion and surface spots on ultra-thin Invar alloy sheets, ensuring substrate surface quality and providing an ideal surface condition for subsequent oil grinding processes.

[0126] To address the issues of secondary oxidation of ultra-thin Invar alloys after pickling and the easy adsorption of impurities on the surface, a closed-loop post-treatment process of "water washing-passivation-drying" was designed to achieve triple protection of "no residue-anti-oxidation-no deformation", resulting in ultra-thin Invar alloy sheets with no oxide layer on the surface and complete structure.

[0127] Specifically, the post-treatment water washing uses deionized water with a conductivity ≤5μS / cm. By optimizing the water quality conditions of the water washing process, secondary pollution is avoided, and the surface quality of the Invar alloy sheet after pickling is better guaranteed.

[0128] Specifically, the water washing temperature is 25-35℃, and the washing time is 3-8 minutes. By controlling the water washing temperature and time, the pickling solution is effectively removed while preventing problems such as thermal deformation of the board.

[0129] For example, the washing temperature is 25°C, 27°C, 29°C, 31°C, 33°C, or 35°C; the washing time is 3 min, 4 min, 5 min, 6 min, 7 min, or 8 min. Preferably, the washing temperature is 27–31°C, and the washing time is 4–6 min.

[0130] Specifically, "washing time" or "rinsing time" refers to the total effective washing time experienced by any point (or unit) on the board from the time it enters the washing area to the time it leaves the washing area.

[0131] Preferably, the pH value of the board surface after washing is 6-7, and the residual acid content on the surface is ≤0.01g / m³. 2 By controlling the pH and the amount of residual acid on the surface, an ideal clean surface is provided for subsequent processes.

[0132] It is understandable that a dense passivation film is formed on the surface of the plate through a passivation reaction. This passivation film has a strong bond with the Invar alloy substrate and does not affect the thermal expansion coefficient of the plate, effectively preventing secondary oxidation of the plate during storage and subsequent processing.

[0133] Specifically, the passivation solution used in the passivation process is an aqueous solution of trivalent chromium or an aqueous solution of sodium chromate with a mass concentration of 5%-10%.

[0134] In some preferred embodiments, the passivation solution used is an aqueous solution of trivalent chromium, wherein the trivalent chromium aqueous solution contains Cr 3+ The molar concentration is 0.2–0.8 mol / L; for example, Cr 3+ The molar concentrations are 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, and 0.8 mol / L; preferably 0.4–0.6 mol / L.

[0135] For example, the trivalent chromium aqueous solution is selected from one or a combination of several of the following: chromium sulfate (Cr2(SO4)3) aqueous solution, chromium chloride (CrCl3) aqueous solution, chromium phosphate (CrPO4) hydrochloric acid solution, chromium oxalate (Cr2(C2O4)3) aqueous solution, chromium sulfate-phosphoric acid complex aqueous solution, chromium chloride-hydroxyethylidene diphosphonic acid complex aqueous solution, and chromium nitrate (Cr(NO3)3) aqueous solution.

[0136] In a preferred embodiment, the trivalent chromium aqueous solution is a chromium sulfate-phosphoric acid composite aqueous solution, wherein Cr... 3+ The molar concentration of phosphoric acid is 0.2–0.8 mol / L, and the concentration range of phosphoric acid is 10–20 g / L (mass concentration 0.98%–2.02%).

[0137] In a preferred embodiment, the chromium phosphate (CrPO4) hydrochloric acid solution contains Cr... 3+ The molar concentration of the HCl is 0.2–0.8 mol / L; the mass concentration of the HCl is 5%–12%, preferably 8%–10%.

[0138] In a preferred embodiment, in the chromium chloride-hydroxyethylidene diphosphonic acid composite aqueous solution, Cr 3+ The molar concentration of hydroxyethylidene diphosphonic acid is 0.2–0.8 mol / L; the concentration of hydroxyethylidene diphosphonic acid is 0.5–3 g / L, preferably, the concentration of hydroxyethylidene diphosphonic acid is 1.5–2 g / L.

[0139] Specifically, the passivation temperature is 40-60℃, and the passivation time is 2-5 minutes.

[0140] For example, the passivation temperatures are 40°C, 45°C, 50°C, 55°C, and 60°C. The passivation times are 2 min, 3 min, 3.5 min, 4 min, and 5 min.

[0141] Preferably, the passivation temperature is 45–55°C, and the passivation time is 3–4 minutes.

[0142] By controlling the concentration of the passivation solution and the passivation process parameters, a dense passivation film of suitable thickness can be formed on the surface of Invar alloy sheets. This passivation film layer is firmly bonded to the substrate and does not affect the thermal expansion characteristics of the material. It can effectively prevent secondary oxidation of the sheet during storage and subsequent processing, ensuring the long-term stability of the product.

[0143] After the passivation step is completed, the waste passivation liquid can be treated by chemical precipitation. After solid-liquid separation, the precipitate is disposed of in accordance with hazardous waste regulations, and the supernatant is discharged safely after meeting the standards. Alternatively, after filtration and purification to remove impurities, the consumed passivation liquid can be replenished to achieve recycling and reduce costs.

[0144] Specifically, after passivation, a passivation solution cleaning step is also included; the surface of the Invar alloy plate is rinsed with deionized water at a pressure of 0.2-0.4 MPa, and the water flow rate during rinsing is controlled at 0.4-0.7 m / s; the rinsing time is 3-5 min.

[0145] It is understandable that using ultra-low pressure deionized water and controlling the water flow rate can prevent damage to the passivation film layer; for example, by using symmetrical multi-hole nozzles to make the water flow into a fine mist, the contact area is increased and the impact force is dispersed, so as to achieve the cleaning of the surface of ultra-thin Invar alloy plates with ultra-low pressure deionized water.

[0146] It should be noted that by controlling the water flow parameters during the post-passivation cleaning process, the passivation film layer is effectively protected from damage while ensuring the effective removal of surface residues.

[0147] Specifically, a smooth strip conveying mechanism is installed within the washing (rinsing) device to ensure that both sides of the Invar alloy sheet (strip) are evenly rinsed. For example, the strip conveying speed is 0.8–1.0 m / s.

[0148] Preferably, in the passivation solution cleaning process, the water flow is made into a fine mist by using a multi-hole nozzle with symmetrical upper and lower parts, which increases the contact area and disperses the impact force.

[0149] For example, in passivation solution cleaning, the nozzle uses nozzles with an aperture of 0.15 mm to 0.3 mm, arranged in a honeycomb pattern with 30 to 50 holes per square centimeter; under a working pressure of 0.2 MPa to 0.4 MPa, a fine mist flow with an average droplet diameter of 50 μm to 120 μm is formed; the distance between the nozzle end face and the workpiece surface is maintained within the range of 100 mm to 200 mm, and the strip is cleaned by continuous spraying.

[0150] Specifically, the drying temperature is 60-80℃. Exemplarily, the drying temperature is 60℃, 65℃, 70℃, 75℃, or 80℃; preferably, the drying temperature is 65-75℃.

[0151] Specifically, the air velocity during the drying process is 1.0-1.5 m / s. For example, the air velocity during the drying process is 1.0 m / s, 1.1 m / s, 1.2 m / s, 1.3 m / s, 1.4 m / s, or 1.5 m / s. Preferably, the air velocity during the drying process is 1.2 to 1.4 m / s.

[0152] Specifically, the drying time is 8-15 minutes. Examples include 8 minutes, 9 minutes, 10 minutes, 11 minutes, 13 minutes, and 15 minutes. Preferably, the drying time is 10-13 minutes.

[0153] By controlling the drying temperature, time, and airflow parameters, a balance was achieved between efficient moisture removal and material dimensional stability. This avoided localized high temperatures that could cause shrinkage and deformation of the ultra-thin sheet, ensuring that there was no moisture residue on the sheet surface and that the flatness error remained at the initial process level.

[0154] Specifically, after the drying step, the obtained ultrathin Invar alloy sheet is evaluated, and the evaluation includes:

[0155] The surface roughness of the plate is tested, and the acceptable standard is Ra≤0.2μm; and / or,

[0156] The oxide layer removal rate of the board material is tested, and the pass standard is an oxide layer removal rate ≥ 98%; and / or,

[0157] The integrity of the crystal structure of the plate is tested, and the pass standard is the absence of lattice distortion or phase transition.

[0158] Furthermore, when all the above indicators meet the requirements, the pickled ultra-thin Invar alloy sheet is judged to meet the electronic grade material standard.

[0159] For example, detecting the surface roughness of the plate includes: using a surface roughness meter to detect the surface roughness (Ra) of the pickled ultra-thin Invar alloy plate, selecting N detection points (N≥5) along the "parallel rolling direction + perpendicular rolling direction" on the surface of the pickled plate, and detecting the surface roughness at each point to avoid ignoring the local roughness differences caused by the anisotropy of rolling of the ultra-thin plate, requiring that Ra≤0.2μm for all detection points.

[0160] For example, detecting the oxide layer removal rate of the plate includes: observing the surface morphology of the ultra-thin Invar alloy plate before and after pickling using a scanning electron microscope (SEM), comparing the cross-sections of the un-pickled and pickled samples of the same batch, measuring the oxide layer thickness before pickling and the residual oxide layer thickness after pickling, and calculating the oxide layer removal rate according to the formula: Oxide layer removal rate = ((Oxide layer thickness before pickling - Residual oxide layer thickness after pickling) / Oxide layer thickness before pickling) × 100%. This avoids the subjective error of traditional visual judgment and requires an oxide layer removal rate of ≥98%.

[0161] For example, detecting the crystal structure integrity of the plate includes: using an X-ray diffractometer (XRD) to analyze the crystal structure of the pickled ultrathin Invar alloy plate, comparing it with the standard Invar alloy XRD pattern without pickling, detecting whether lattice distortion or phase transformation occurs, ensuring that the crystal structure of the plate is intact after pickling, and that its extremely low coefficient of thermal expansion is not affected, thus meeting the stringent requirements of precision instruments for dimensional stability.

[0162] When using X-ray diffraction (XRD) analysis, the standard Invar alloy (Ni36) XRD pattern without acid washing is used as the benchmark: the position deviation of the characteristic diffraction peaks (such as 2θ = 43.5°, 50.7°, 74.5°) of the acid-washed plate is ≤ ±0.1°, which is judged as no lattice distortion; no new diffraction peaks (such as diffraction peaks related to nickel oxide and iron oxide) appear, and the original characteristic diffraction peaks do not split, broaden or have abnormal intensity decay (relative intensity deviation ≤ 5%), which is judged as no phase transition.

[0163] The composition of the standard Invar alloy (Ni36) comprises, by mass percentage: Ni: 36%, with the balance being Fe and unavoidable impurities.

[0164] It should be noted that after post-processing, a multi-dimensional evaluation system was established that includes surface quality, oxide layer removal effect, and material structural integrity, thus achieving a comprehensive assessment of the pickling process effect. When all test indicators meet the preset standards, it can be determined that the ultra-thin Invar alloy sheet meets the requirements for electronic-grade materials.

[0165] The "ultra-thin Invar alloy sheet" mentioned in this invention refers to an Invar alloy sheet with a thickness of ≤0.3mm. For example, the thickness of the ultra-thin Invar alloy sheet is 0.1-0.3mm. For instance, the thickness of the ultra-thin Invar alloy sheet is 0.1mm, 0.15mm, 0.20mm, 0.25mm, or 0.30mm.

[0166] In some embodiments, the chemical composition of the "ultra-thin Invar alloy sheet" contains Ni: 35.0%-37.0% by mass, with the balance being Fe and unavoidable impurities.

[0167] In some embodiments, the chemical composition of the "ultra-thin Invar alloy sheet" by mass percentage is Ni: 35.5%–36.5%, C: 0.001%–0.03%, Mn: 0.2%–0.5%, Si: 0–0.1%, Al: 0–0.03%, Cr: 0–0.1%, Nb: 0–0.02%, with the balance being Fe and other unavoidable impurities.

[0168] The technical solution of the present invention will be further described in detail below with reference to specific embodiments and comparative examples.

[0169] Example 1:

[0170] This embodiment provides an acid pickling process for ultra-thin Invar alloy sheet (hereinafter referred to as sheet), including the following steps:

[0171] S1, Surface pretreatment

[0172] The ultra-thin Invar alloy sheet (thickness = 0.1 mm) to be treated was immersed in a degreasing agent solution. The degreasing agent contained sodium hydroxide, sodium carbonate, and fatty alcohol polyoxyethylene ether (i.e., fatty alcohol polyoxyethylene ether-9, AEO-9). The mass ratio of sodium hydroxide, sodium carbonate, and fatty alcohol polyoxyethylene ether was 5:3:2, and the balance was water. The degreasing agent concentration was 10%, the degreasing agent temperature was 50°C, and the surface pretreatment time was 9 min.

[0173] S2, Oil grinding treatment

[0174] The pretreated plates were oil-milled using a silicon carbide grinding head (1000 mesh); the grinding oil consisted of paraffin-based mineral oil (i.e., Kunlun SN150 paraffin-based base oil) and sulfurized isobutylene (i.e., sulfurized isobutylene R-CH2-S). X -CH2-R, x=2, R is isobutyl) are prepared at a mass ratio of 10:1; the oil mill pressure is 0.2MPa, the milling speed is 2.0m / min, and the number of milling cycles is 1; during the milling process, the grinding oil is replenished with a spray rate of 8L / h; the oil mill tension is 26KN.

[0175] S3. Rinse after oil grinding.

[0176] Deionized water at a pressure of 0.8 MPa was used to rinse the oil-polished board through a multi-hole nozzle symmetrically positioned above and below. The water flow rate was 1.2 m / s and the rinsing time was 3 minutes to ensure that the polishing oil was completely removed.

[0177] S4, pickling treatment

[0178] The rinsed substrate is immersed in an pickling solution prepared by mixing a 15 wt.% hydrochloric acid solution and an 8 wt.% nitric acid solution at a volume ratio of 4:1. The pickling solution contains 12% hydrochloric acid and 1.6% nitric acid by mass, with the remainder being water. The mass ratio of hydrochloric acid to nitric acid is 7.5:1. The pickling temperature is 40℃, and the pickling time is 8 minutes. During the pickling process, a mechanical device drives the pickling tank to perform periodic reciprocating motion (amplitude 10 cm, frequency 1.2 Hz) to promote the removal of reaction products, ensuring complete removal of the oxide layer while strictly controlling the substrate loss to ≤1 μm.

[0179] S5, Post-processing

[0180] S51. Water washing: Use deionized water with a conductivity ≤5μS / cm, at a temperature of 30℃, for a washing time of 5 minutes; after washing, the pH value of the board surface is 6.5, and the residual acid content on the board surface is 0.008g / m³. 2 ;

[0181] S52, Passivation: The washed plate is immersed in a chromium sulfate-phosphoric acid composite aqueous solution, wherein chromium sulfate-phosphoric acid composite aqueous solution contains Cr 3+ The molar concentration of the compound was 0.5 mol / L, and the concentration of phosphoric acid was 15 g / L; the passivation temperature was 50℃, and the passivation time was 3 min.

[0182] S53. Passivation solution cleaning: Deionized water with a pressure of 0.3MPa and a flow rate of 0.7m / s is used for rinsing through a multi-hole nozzle with symmetrical upper and lower parts for 4 minutes; at the same time, a strip conveying mechanism is set in the water washing device, with a strip conveying speed of 0.8m / s to ensure that both sides of the strip can be rinsed evenly.

[0183] S54. Drying: Dry the board at a drying temperature of 70℃ and a wind speed of 1.2m / s for 12 minutes.

[0184] S6, Evaluation

[0185] The following tests and evaluations were performed on the pickled ultrathin Invar alloy sheets:

[0186] Surface roughness: The surface roughness (Ra) of the pickled ultra-thin Invar alloy sheet was measured using a surface roughness meter. Five test points were selected on the surface of the pickled sheet along the parallel rolling direction and the perpendicular rolling direction, and the surface roughness at each point was measured. The Ra value of each test point was obtained.

[0187] Oxide layer removal rate: The surface morphology of ultra-thin Invar alloy plates before and after pickling was observed using scanning electron microscopy (SEM). The cross-sections of unpickled and pickled samples from the same batch were compared. The oxide layer thickness before pickling and the residual oxide layer thickness after pickling were measured. The oxide layer removal rate was calculated using the formula (Oxide layer removal rate = ((Oxide layer thickness before pickling - Residual oxide layer thickness after pickling) / Oxide layer thickness before pickling) × 100%, avoiding the subjective error of traditional visual judgment.

[0188] Structural integrity: When using X-ray diffraction (XRD) analysis, the standard Invar alloy (Ni36) XRD pattern without acid washing is used as the benchmark: the position deviation of the characteristic diffraction peaks (such as 2θ = 43.5°, 50.7°, 74.5°) of the acid-washed plate is ≤ ±0.1°, which is judged as no lattice distortion; no new diffraction peaks (such as diffraction peaks related to nickel oxide and iron oxide) appear, and the original characteristic diffraction peaks do not split, broaden or have abnormal intensity attenuation (relative intensity deviation ≤ 5%), which is judged as no phase transition.

[0189] Example 2-1:

[0190] This embodiment is the same as Embodiment 1, except that in the oil grinding process, the grinding oil is composed of paraffin-based mineral oil (i.e., Kunlun SN150 paraffin-based base oil) and sulfurized isobutylene (i.e., sulfurized isobutylene R-CH2-S). X -CH2-R, x=2, R is isobutyl) are compounded in a mass ratio of 8:1.

[0191] Example 2-2:

[0192] This embodiment is the same as Embodiment 1, except that in the oil grinding process, the grinding oil is composed of paraffin-based mineral oil (i.e., Kunlun SN150 paraffin-based base oil) and sulfurized isobutylene (i.e., sulfurized isobutylene R-CH2-S). X -CH2-R, x=2, R is isobutyl) are compounded in a mass ratio of 12:1.

[0193] Examples 2-3:

[0194] This embodiment is the same as Embodiment 1, except that in the oil grinding process, the grinding oil is composed of naphthenic mineral oil (i.e., KN4010 naphthenic base oil) and sulfurized isobutylene (i.e., sulfurized isobutylene R-CH2-S). X -CH2-R, x=3, R is isobutyl) are compounded in a mass ratio of 10:1.

[0195] Examples 2-4:

[0196] This embodiment is the same as Embodiment 1, except that in the oil grinding process, the grinding oil is composed of intermediate-based mineral oil (i.e., Sinopec 150SN intermediate-based base oil) and sulfurized isobutylene (i.e., sulfurized isobutylene R-CH2-S). X -CH2-R, x=2, R is isobutyl) are compounded in a mass ratio of 10:1.

[0197] Examples 2-5:

[0198] This embodiment is the same as Embodiment 1, except that in the oil grinding process, the grinding oil is composed of light white oil (i.e., Kunlun L-10 light white oil) and sulfurized isobutylene (i.e., sulfurized isobutylene R-CH2-S). X -CH2-R, x=3, R is isobutyl) are compounded in a mass ratio of 10:1.

[0199] Examples 2-6:

[0200] This embodiment is the same as Embodiment 1, except that in the oil grinding process, the grinding oil is a mixture of paraffinic mineral oil (i.e., Great Wall L-AN46 paraffinic system oil) and naphthenic mineral oil (i.e., Great Wall 45# naphthenic base oil) in a mass ratio of 1:1, and sulfurized isobutylene (i.e., sulfurized isobutylene R-CH2-S). X -CH2-R, x=2, R is isobutyl) are compounded in a mass ratio of 10:1.

[0201] Examples 2-7

[0202] This embodiment is the same as Embodiment 1, except that in the oil grinding process, the grinding oil is a compound of paraffin-based mineral oil (i.e., Great Wall L-AN46 paraffin-based system oil) and dibenzyl disulfide in a mass ratio of 10:1.

[0203] Examples 2-8

[0204] This embodiment is the same as Embodiment 1, except that in the oil grinding process, the grinding oil is a compound of paraffin-based mineral oil (i.e., Sinopec Maoming 100SN paraffin-based process oil) and phosphate ester amine salt (tricresol phosphate ester amine salt T306) in a mass ratio of 10:1.

[0205] Examples 2-9

[0206] This embodiment is the same as Embodiment 1, except that in the oil grinding process, the grinding oil is a compound of paraffin-based mineral oil (i.e., Sinopec Maoming 100SN paraffin-based process oil) and borate ester (i.e., tributyl borate T361) in a mass ratio of 10:1.

[0207] Example 2-10

[0208] This embodiment is the same as Embodiment 1, except that in the oil grinding process, the grinding oil is a compound of naphthenic mineral oil (i.e., Kunlun KN4010 naphthenic base oil) and phosphate ester amine salt (i.e., triphenyl phosphate amine salt T307) in a mass ratio of 11:1.

[0209] Example 2-11

[0210] This embodiment is the same as Embodiment 1, except that in the oil grinding process, the grinding oil is a compound of intermediate base mineral oil (i.e., CNOOC HVI250 intermediate base oil) and dibenzyl disulfide in a mass ratio of 9:1.

[0211] Example 3-1

[0212] This embodiment is the same as Embodiment 1, except that in the surface pretreatment, the degreasing agent contains sodium hydroxide, sodium carbonate and fatty alcohol polyoxyethylene ether (i.e., fatty alcohol polyoxyethylene ether-7, AEO-7), the mass ratio of sodium hydroxide, sodium carbonate and fatty alcohol polyoxyethylene ether is 4:2:1, and the balance is water; the mass concentration of the degreasing agent is 8%, the degreasing agent temperature is 40°C, and the surface pretreatment time is 8 min.

[0213] Example 3-2

[0214] This embodiment is the same as Embodiment 1, except that in the surface pretreatment, the degreasing agent contains sodium hydroxide, sodium carbonate and fatty alcohol polyoxyethylene ether (i.e., fatty alcohol polyoxyethylene ether-15, AEO-15), the mass ratio of sodium hydroxide, sodium carbonate and fatty alcohol polyoxyethylene ether is 6:4:3, and the balance is water; the mass concentration of the degreasing agent is 15%, the degreasing agent temperature is 55°C, and the surface pretreatment time is 10 min.

[0215] Example 4-1

[0216] This embodiment is the same as Embodiment 1, except that in the oil grinding process, a silicon carbide grinding head (800 mesh) is used to perform oil grinding on the pretreated board; the oil grinding pressure is 0.1 MPa, the grinding speed is 1.0 m / min, and the number of grinding times is 2; during the grinding process, the grinding oil is replenished by spraying at a rate of 5 L / h.

[0217] Example 4-2

[0218] This embodiment is the same as Embodiment 1, except that in the oil grinding process, a silicon carbide grinding head (1200 mesh) is used to perform oil grinding on the pretreated board; the oil grinding pressure is 0.3 MPa, the grinding speed is 3.0 m / min, and the grinding is performed once; during the grinding process, the grinding oil is replenished with a spray rate of 10 L / h.

[0219] Example 5-1

[0220] This embodiment is the same as Embodiment 1, except that in the oil grinding process, the oil grinding tension is 20KN; in the post-oil grinding rinsing, deionized water with a pressure of 0.6MPa is used to rinse the oil-ground board through a multi-hole nozzle with symmetrical upper and lower parts, the water flow rate is 1.0m / s, and the rinsing time is 2min.

[0221] Example 5-2

[0222] This embodiment is the same as Embodiment 1, except that in the oil grinding process, the oil grinding tension is 30KN; in the post-oil grinding rinsing, deionized water with a pressure of 0.9MPa is used to rinse the oil-ground board through symmetrical multi-hole nozzles, the water flow rate is 1.5m / s, and the rinsing time is 4min.

[0223] Example 6-1

[0224] This embodiment is the same as Embodiment 1, except that in the pickling process, the pickling solution contains 9.2% hydrochloric acid and 2.3% nitric acid by mass, with the remainder being water, and the mass ratio of hydrochloric acid to nitric acid is 4:1.

[0225] Example 6-2

[0226] This embodiment is the same as Embodiment 1, except that in the pickling process, the pickling solution contains 15% hydrochloric acid and 1.2% nitric acid by mass, with the remainder being water, and the mass ratio of hydrochloric acid to nitric acid is 12.5:1.

[0227] Example 6-3

[0228] This embodiment is the same as Embodiment 1, except that in the pickling process, the pickling solution contains 18% hydrochloric acid and 0.5% nitric acid by mass, with the remainder being water, and the mass ratio of hydrochloric acid to nitric acid is 36:1.

[0229] Example 6-4

[0230] This embodiment is the same as Embodiment 1, except that in the pickling process, the pickling solution contains 7.0% hydrochloric acid and 3.0% nitric acid by mass, with the remainder being water, and the mass ratio of hydrochloric acid to nitric acid is 2.3:1.

[0231] Example 7-1

[0232] This embodiment is the same as Embodiment 1, except that the pickling temperature is 30°C and the pickling time is 15 minutes.

[0233] Example 7-2

[0234] This embodiment is the same as Embodiment 1, except that the pickling temperature is 50°C and the pickling time is 5 minutes.

[0235] Example 7-3

[0236] This embodiment is the same as Embodiment 1, except that in the pickling process, the amplitude is 6cm and the frequency is 0.8Hz.

[0237] Example 7-4

[0238] This embodiment is the same as Embodiment 1, except that the amplitude is 15cm and the frequency is 2.0Hz in the pickling process.

[0239] Example 7-5

[0240] This embodiment is the same as Embodiment 1, except that the pickling process does not employ periodic reciprocating motion.

[0241] Example 8

[0242] This embodiment is the same as Embodiment 1, except that: in the passivation process of the post-treatment, the passivation solution used is an aqueous solution of chromium phosphate (CrPO4) dissolved in hydrochloric acid, wherein Cr... 3+ The molar concentration of the active ingredient was 0.2 mol / L, the mass concentration of hydrochloric acid (HCl) was 8%, the passivation temperature was 60℃, and the passivation time was 2 min.

[0243] Example 9

[0244] This embodiment is the same as Embodiment 1, except that: in the passivation process of the post-treatment, the passivation solution used is a chromium chloride-hydroxyethylidene diphosphonic acid composite aqueous solution, wherein the chromium chloride-hydroxyethylidene diphosphonic acid composite aqueous solution contains Cr 3+ The molar concentration of the passivation solution is 0.8 mol / L, and the concentration of hydroxyethylidene diphosphonic acid is 2 g / L. In the passivation solution cleaning step after passivation, deionized water with a pressure of 0.4 MPa is used for rinsing, and the water flow rate during rinsing is controlled at 0.4 m / s.

[0245] Example 10

[0246] This embodiment is the same as Embodiment 1, except that the thickness of the ultra-thin Invar alloy sheet to be processed is 0.2 mm.

[0247] Example 11

[0248] This embodiment is the same as Embodiment 1, except that the thickness of the ultra-thin Invar alloy sheet to be processed is 0.3 mm.

[0249] In addition, from Figure 4 It can be seen that the pickling process provided in this embodiment of the invention produces ultra-thin Invar alloy sheets with good surface quality and flat shape.

[0250] Comparative Example 1

[0251] This comparative example is the same as Example 1, except that it lacks the oil grinding treatment and the subsequent rinsing step. After the surface pretreatment, the pickling treatment and post-treatment steps are performed directly.

[0252] Comparative Example 2-1

[0253] This comparative example is the same as Example 1, except that: in the pickling process, a single hydrochloric acid solution with a mass concentration of 25% is used as the pickling solution.

[0254] Comparative Example 2-2

[0255] This comparative example is the same as Example 1, except that: in the pickling process, a single nitric acid solution with a mass concentration of 10% is used as the pickling solution.

[0256] Comparative Examples 2-3

[0257] This comparative example is the same as Example 1, except that: in the pickling treatment, the pickling solution is a mixed aqueous solution of hydrochloric acid and nitric acid, which contains 7% hydrochloric acid and 4.0% nitric acid by mass percentage based on the total mass of the pickling solution, with the remainder being water.

[0258] Comparative Examples 2-4

[0259] This comparative example is the same as Example 1, except that: in the pickling treatment, the pickling solution is a mixed aqueous solution of hydrochloric acid and nitric acid, which contains 18% hydrochloric acid and 0.2% nitric acid by mass percentage, with the remainder being water, based on the total mass of the pickling solution.

[0260] Comparative Examples 2-5

[0261] This comparative example is the same as Example 1, except that: in the pickling treatment, the pickling solution is a mixed aqueous solution of hydrochloric acid and nitric acid, which contains 30% hydrochloric acid and 10.0% nitric acid by mass percentage, with the remainder being water, based on the total mass of the pickling solution; the mass ratio of hydrochloric acid to nitric acid is 3:1.

[0262] Comparative Examples 2-6

[0263] This comparative example is the same as Example 1, except that: in the pickling treatment, the pickling solution is a mixed aqueous solution of hydrochloric acid, nitric acid and hydrofluoric acid, and based on the total mass of the pickling solution, it contains 12% hydrochloric acid, 8% nitric acid and 2% hydrofluoric acid by mass percentage, with the remainder being water.

[0264] Comparative Examples 2-7

[0265] This comparative example is the same as Example 1, except that: in the pickling treatment, the pickling solution is a mixed aqueous solution of sulfuric acid and nitric acid, which contains 18% sulfuric acid and 6% nitric acid by mass percentage based on the total mass of the pickling solution, with the remainder being water.

[0266] Comparative Examples 2-8

[0267] This comparative example is the same as Example 1, except that: in the pickling treatment, a pickling solution of hydrofluoric acid and nitric acid is used, the mass concentration of hydrofluoric acid in the pickling solution is 10%, the mass concentration of nitric acid is 15%, and the remainder is water.

[0268] Comparative Examples 2-9

[0269] This comparative example is the same as Example 1, except that: in the pickling treatment, a pickling solution of hydrofluoric acid and nitric acid is used, the mass concentration of hydrofluoric acid in the pickling solution is 2%, the mass concentration of nitric acid is 25%, and the remainder is water.

[0270] Comparative Examples 2-10

[0271] This comparative example is the same as Example 1, except that: in the pickling treatment, a pickling solution of sulfuric acid, nitric acid and hydrofluoric acid is used; in the pickling solution, the mass concentration of sulfuric acid is 50%, the mass concentration of nitric acid is 10%, the mass concentration of hydrofluoric acid is 2%, and the remainder is water.

[0272] Comparative Example 2-11

[0273] This comparative example is the same as Example 1, except that: in the pickling treatment, the pickling solution contains 10% glycerol, 10% hydrochloric acid, 40% ferric chloride, 5% copper chloride, and the remainder is water, based on the mass percentage of each component in the pickling solution.

[0274] Comparative Example 2-12

[0275] This comparative example is the same as Example 1, except that: in the pickling treatment, the pickling solution is a mixed aqueous solution of nitric acid and fluorosilicic acid, which contains 12% nitric acid and 3% fluorosilicic acid by mass percentage, with the remainder being water, based on the total mass of the pickling solution.

[0276] Comparative Example 2-13

[0277] This comparative example is the same as Example 1, except that the pickling solution is a mixed aqueous solution of hydrochloric acid and ammonium bifluoride. Based on the total mass of the pickling solution, the pickling solution contains 10% hydrochloric acid and 5% ammonium bifluoride by mass, with the remainder being water.

[0278] Comparative Example 2-14

[0279] This comparative example is the same as Example 1, except that the pickling solution is a mixed aqueous solution of hydrochloric acid and hydrogen peroxide. Based on the total mass of the pickling solution, the pickling solution contains 12% hydrochloric acid and 5% hydrogen peroxide by mass percentage, with the remainder being water.

[0280] Comparative Example 2-15

[0281] This comparative example is the same as Example 1, except that the pickling solution is a mixed aqueous solution of nitric acid and citric acid. Based on the total mass of the pickling solution, the pickling solution contains 8% nitric acid and 3% citric acid by mass percentage, with the remainder being water.

[0282] Comparative Example 3

[0283] This comparative example is the same as Example 1, except that the passivation and passivation solution cleaning steps are omitted in the post-processing, and the product is directly dried after water washing.

[0284] Comparative Example 4

[0285] This comparative example is the same as Example 1, except that a rigid metal-based grinding wheel is used in the oil grinding process, specifically: a cast iron base + electroplated diamond abrasive with a grit size of 1000 mesh. Other parameters such as oil grinding pressure and grinding speed remain consistent with Example 1.

[0286] Comparative Example 5-1

[0287] This comparative example is the same as Example 1, except that in the oil grinding process, the grinding oil consists of paraffin-based mineral oil (i.e., Kunlun SN150 paraffin-based base oil) and sulfurized isobutylene (i.e., sulfurized isobutylene R-CH2-S). X -CH2-R, x=2, R is isobutyl) are compounded in a mass ratio of 20:1.

[0288] Comparative Example 5-2

[0289] This comparative example is the same as Example 1, except that in the oil grinding process, the grinding oil consists of paraffin-based mineral oil (i.e., Kunlun SN150 paraffin-based base oil) and sulfurized isobutylene (i.e., sulfurized isobutylene R-CH2-S). X -CH2-R, x=2, R is isobutyl) are compounded in a mass ratio of 5:1.

[0290] Table 1 Test results of the examples and comparative examples

[0291]

[0292]

[0293]

[0294]

[0295]

[0296] pass Figure 5 and Figure 6 In contrast, the pickling process provided in this embodiment of the invention results in significantly lower lattice stress.

[0297] from Figure 7 and Figure 8 It can be seen that the pickling process provided in the embodiments of the present invention ensures the structural integrity of the ultra-thin Invar alloy sheet.

[0298] from Figures 9-10 It can be seen that, compared with the existing pickling process, the pickling process provided by the embodiments of the present invention results in a better surface quality of the board.

[0299] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A pickling process for ultra-thin Invar alloy sheets, characterized in that, Includes the following steps: Surface pretreatment, oil grinding, post-oil grinding rinsing, pickling, and post-treatment; The pickling process uses a pickling solution containing hydrochloric acid and nitric acid; The post-processing includes washing, passivation, and drying.

2. The pickling process according to claim 1, characterized in that, In the oil milling process, the grinding oil used contains mineral oil and extreme pressure agent, wherein the mass ratio of mineral oil to extreme pressure agent is (8-12):1; and / or, The oil mill pressure is 0.1-0.3 MPa; and / or, The grinding speed is 1-3 m / min; and / or, The polishing process is repeated 1-2 times.

3. The pickling process according to claim 1, characterized in that, The oil milling process employs a silicon carbide grinding head with a particle size of 800-1200 mesh; and / or, During the polishing process, the polishing oil is replenished with a spray rate of 5-10 L / h.

4. The pickling process according to claim 1, characterized in that, In the pickling process, the pickling solution is a mixed aqueous solution of hydrochloric acid and nitric acid, comprising 7%-18% hydrochloric acid and 0.5%-3.0% nitric acid by mass, with the balance being water; and / or, Pickling temperature is 30-50℃; and / or, Pickling time is 5-15 minutes.

5. The pickling process according to claim 1, characterized in that, In the surface pretreatment, the degreasing agent used comprises sodium hydroxide, sodium carbonate, and a nonionic surfactant, wherein the mass ratio of sodium hydroxide, sodium carbonate, and nonionic surfactant is (4-6):(2-4):(1-3); and / or, The working mass concentration of the degreasing agent is 8%-15%.

6. The pickling process according to claim 1, characterized in that, The post-treatment water washing uses deionized water with a conductivity ≤ 5 μS / cm; and / or, The washing temperature is 25-35℃; and / or, After washing, the pH value of the board surface is 6-7, and the residual acid content on the surface is ≤0.01g / m². 2 .

7. The pickling process according to claim 1, characterized in that, In the passivation process, the passivation solution used is a trivalent chromium aqueous solution, wherein the trivalent chromium aqueous solution contains Cr 3+ The molar concentration is 0.2–0.8 mol / L; and / or, The passivation temperature is 40-60℃; and / or, The passivation time is 2-5 minutes.

8. The pickling process according to claim 1, characterized in that, The passivation process includes a passivation solution cleaning step; deionized water with a pressure of 0.2-0.4 MPa is used for rinsing, and the water flow rate during rinsing is controlled at 0.4-0.7 m / s.

9. The pickling process according to claim 1, characterized in that, The drying temperature is 60-80℃; and / or, The air velocity during the drying process is 1-1.5 m / s.

10. The pickling process according to claim 1, characterized in that, After the drying process, the resulting ultrathin Invar alloy sheet is evaluated, including: The surface roughness of the plate is tested, and the acceptable standard is Ra≤0.2μm; and / or, The oxide layer removal rate of the board material is tested, and the pass standard is an oxide layer removal rate ≥ 98%; and / or, The integrity of the crystal structure of the plate is tested, and the pass standard is the absence of lattice distortion or phase transition.

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