High and low temperature resistant strong corrosion silicon crystal composite treatment process

Abstract

This invention provides a silicon crystal composite treatment process resistant to high and low temperature strong corrosion, relating to the field of metal surface treatment technology, comprising the following steps: S1: degreasing the workpiece to be cleaned; S2: washing the degreased workpiece with water; S3: immersing the washed workpiece in a silicon crystal resist for silicon crystal composite treatment; S4: drying the silicon crystal resist after silicon crystal composite treatment; wherein, based on the mass of the silicon crystal resist, the silicon crystal resist comprises the following components: 5-10% terminal amino silane coupling agent, 5-10% terminal epoxy silane coupling agent, 3-7% block copolymer, 10-18% waterborne polyurethane containing dynamic disulfide bonds, 4-10% modified nano-silica, 2-6% polyaniline conductive polymer, 1-3% corrosion inhibitor, and the remainder being water. This invention solves the problems of limited metal types, complex processes, and insufficient film adhesion and corrosion resistance in existing technologies.

Description

Technical Field

[0001] This invention relates to the field of metal surface treatment technology, and in particular to a silicon crystal composite treatment process resistant to high and low temperature strong corrosion. Background Technology

[0002] Traditional metal surface treatment technologies such as phosphating and chromating have long dominated industrial applications, but their inherent technical shortcomings are becoming increasingly apparent. Phosphating is typically only applicable to steel parts; for materials such as aluminum, copper, and stainless steel, the bath solution must be changed or different processes must be used, resulting in poor production line flexibility and complex management. The process requires the use of various auxiliary agents such as surface conditioners, accelerators, and passivators, with 8-10 steps and heating to 50-70℃, leading to high energy consumption. The production process generates a large amount of phosphating slag, producing approximately 2-5 kg ​​of waste slag per ton of workpieces processed, along with the discharge of wastewater containing phosphorus, nickel, manganese, and other heavy metals, resulting in high environmental treatment costs. In terms of performance, iron-based phosphating can only achieve about 300 hours of neutral salt spray testing, and zinc-based phosphating can only reach a maximum of 500 hours. Furthermore, the bare film is extremely prone to rusting during storage and has poor high and low temperature resistance, failing to meet the long-term protection requirements of high-end manufacturing fields such as automobiles and aerospace. Although chromating is widely used in aluminum materials, hexavalent chromium is highly carcinogenic and has been strictly restricted by environmental regulations such as RoHS and REACH, and is facing elimination.

[0003] In recent years, ceramic coating (zirconization) and silane treatment technologies have been developed as alternatives, improving environmental friendliness and adhesion to some extent. Ceramic coating technology uses fluorozirconic acid as the main film-forming substance, is phosphorus-free and heavy metal-free, but the film layer is extremely thin (only 20-50 nm), lacks density, and its corrosion resistance is usually only equivalent to that of iron-based phosphating. Furthermore, it has extremely stringent requirements for pretreatment cleanliness, a narrow process window, and poor bath stability. While ordinary silane treatment technology can achieve multi-metal collinear processing, its film layer has a single homogeneous structure, and its adhesion is highly sensitive to the quality of the pretreatment. Silane films are prone to hydrolysis before curing, requiring strict control of water washing conditions during the process, making operation difficult. It lacks self-healing capabilities; once the film layer is damaged, corrosion rapidly spreads from the defect. Its resistance to high and low temperatures is limited, easily cracking and failing in environments below -20℃ or above 150℃.

[0004] Therefore, existing technologies still cannot simultaneously meet the comprehensive requirements of multi-metal versatility, high corrosion resistance, resistance to high and low temperature impacts, green environmental protection, and process stability. There is an urgent need to develop a composite treatment process with strong adaptability and excellent performance. Summary of the Invention

[0005] The present invention aims to provide a silicon crystal composite processing technology that is resistant to high and low temperatures and strong corrosion, and solves the problems of limited metal types, complex processes, and insufficient film adhesion and corrosion resistance in the existing technology.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a silicon crystal composite processing technology resistant to high and low temperature strong corrosion, characterized by comprising the following steps: S1: Degrease the workpiece to be cleaned; S2: Wash the degreased workpiece with water; S3: Immerse the washed workpiece in silicon crystal resist for silicon crystal composite treatment; S4: Dry the workpiece after silicon crystal composite treatment; The silicon crystal resist comprises, by weight, the following components: 5-10% amino-terminated silane coupling agent, 5-10% epoxy-terminated silane coupling agent, 3-7% block copolymer, 10-18% waterborne polyurethane containing dynamic disulfide bonds, 4-10% modified nano-silica, 2-6% polyaniline conductive polymer, 1-3% corrosion inhibitor, and the remainder being water.

[0007] Furthermore, based on the above technical solution, the terminal aminosilane coupling agent includes one or more of γ-aminopropyltriethoxysilane, aminopropyltriethoxysilane, and γ-aminopropyltriethoxysilane. And / or, the terminal epoxy silane coupling agent includes one or more of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-glycidyl etheroxypropyltrimethoxysilane, and γ-glycidyl etheroxypropyltrimethoxysilane. And / or, the block copolymer is PEO-PPO-PEO; And / or, the particle size of the modified nano silica is 10-60 nm, and its preparation method is as follows: impregnate nano silica in mercaptosilane coupling agent KH-590 for 1-2 h to obtain modified nano silica; And / or, the polyaniline conductive polymer includes one or more of intrinsic polyaniline, hydrochloric acid-doped polyaniline, and sulfosalicylic acid-doped polyaniline; And / or, the corrosion inhibitor is a benzotriazole corrosion inhibitor, including one or more of benzotriazole, methylbenzotriazole, and carboxybenzotriazole.

[0008] Furthermore, based on the above technical solution, the waterborne polyurethane containing dynamic disulfide bonds, by mass parts, includes 30-40 parts of polycarbonate diol, 15-20 parts of isophorone diisocyanate, 2-5 parts of dithiodiethanol, 3-5 parts of dimethylolpropionic acid, 2-4 parts of triethylamine, 0.5-1.5 parts of ethylenediamine, and 0.01-0.03 parts of dibutyltin dilaurate.

[0009] Furthermore, based on the above technical solution, the preparation method of the aqueous polyurethane containing dynamic disulfide bonds includes the following steps: (1) Polycarbonate diol, isophorone diisocyanate and dibutyltin dilaurate are added to a reaction vessel to carry out a prepolymerization reaction to obtain the first reaction solution; (2) Add dithiodiethanol to the first reaction solution and react to obtain the second reaction solution; (3) Add dimethylolpropionic acid to the second reaction solution to carry out the reaction and obtain the third reaction solution; (4) Cool the third reaction solution to 40°C and add triethylamine for neutralization to obtain the fourth reaction solution; (5) Under high-speed stirring, deionized water is added to the fourth reaction solution in batches to disperse and emulsify, thereby obtaining an emulsified reaction solution; (6) Add ethylenediamine to the emulsion reaction solution and stir to obtain waterborne polyurethane containing dynamic disulfide bonds.

[0010] Furthermore, based on the above technical solution, the temperature of the prepolymerization reaction is 80-90℃ and the time is 2-3 hours; And / or, the reaction temperature in step (2) is 75-85℃ and the time is 1-2h; And / or, the reaction temperature in step (3) is 75-85℃ and the time is 1-2h; And / or, the neutralization reaction in step (4) is stopped when the pH reaches 7-9; And / or, in step (5), the volume ratio of deionized water to the fourth reaction solution is (1-3):(1-3); the emulsification reaction temperature is 25-35℃, the time is 30-40min; the high-speed stirring rate is 1500-3000 rpm; And / or, in step (6), ethylenediamine is added to the emulsion reaction solution and stirred for 30-40 minutes.

[0011] Furthermore, based on the above technical solution, the preparation method of the silicon resist includes the following steps: Add silane hydrolysate to the reactor, slowly add block copolymer solution while stirring, and continue stirring for 10-15 min; then slowly add waterborne polyurethane containing dynamic disulfide bonds, and continue stirring for 10-15 min; further slowly add nano silica dispersion, and continue stirring for 15-25 min, adjust pH to 8.5-9.5, let stand and mature at 25-35℃ for 12-24 h, filter, and obtain silicon crystal resist.

[0012] Furthermore, based on the above technical solution, the silane hydrolysate is obtained by mixing an amino-terminated silane coupling agent with an epoxy-terminated silane coupling agent, adding deionized water, and stirring and hydrolyzing at room temperature for 30-60 minutes. And / or, the block copolymer solution is prepared by adding the block copolymer to deionized water, heating to 40-50°C and stirring to dissolve, and then cooling to room temperature for later use; And / or, the nano silica dispersion is prepared by slowly adding modified nano silica to deionized water, shearing and dispersing it at a high speed of 2000-3000 rpm until uniform, and then allowing it to stand to defoam before use. And / or, the silicon resist has a pH of 8.5-9.5, a solid content of 12-25%, and a viscosity of 50-200 mPa·s at room temperature.

[0013] Furthermore, based on the above technical solution, in step S1, the degreasing treatment includes pre-degreasing and main degreasing; The pre-degreasing includes using an alkaline degreasing agent and spraying it at a temperature of 50-60℃ for 3-5 minutes. The main degreasing process includes ultrasonic treatment in an alkaline degreasing agent at a temperature of 55-65℃ for 10-20 minutes, followed by immersion treatment for 5-8 minutes.

[0014] Furthermore, based on the above technical solution, in step S2, the water washing adopts a three-stage countercurrent rinsing process; Washing time per stage: 1-2 minutes; Water quality for washing: Deionized water or softened water, conductivity ≤200μS / cm; And / or, in step S3, the temperature of the silicon crystal composite treatment is 25-35℃, the treatment time is 3-6 min, and the pH is 8.5-9.5.

[0015] Furthermore, based on the above technical solution, the drying process employs an infrared-hot air composite drying process, which is carried out in two stages: Phase 1: Infrared radiation, wavelength 2-4μm, temperature 60-70℃, time 3-5min; Second stage: Hot air circulation drying, temperature 80-100℃, time 10-15min; And / or, the thickness of the dried film is 0.5-3 μm.

[0016] The silicon crystal composite processing technology provided by this invention, which is resistant to high and low temperature corrosion, has the following beneficial effects: 1. This invention eliminates the complex surface conditioning, promotion, passivation and other processes in the traditional phosphating and chromating process. It can be completed in only four steps: "degreasing → water washing → silicon crystal composite treatment → drying". Moreover, the silicon crystal composite treatment can be directly dried without water washing.

[0017] 2. This process can process various metals such as iron, aluminum, copper, and stainless steel at room temperature (25-35℃) without changing the silicon crystal resist bath or adjusting process parameters, making the production line extremely flexible. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Those skilled in the art should understand that the embodiments described are merely illustrative of the invention and should not be considered as specific limitations thereof. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. Process parameters not specifically specified in the following embodiments are generally performed under conventional conditions.

[0019] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0020] According to a first aspect of the present invention, a silicon crystal composite processing technology resistant to high and low temperature strong corrosion is provided, comprising the following steps: S1: Degrease the workpiece to be cleaned; S2: Wash the degreased workpiece with water; S3: Immerse the washed workpiece in silicon crystal resist for silicon crystal composite treatment; S4: Dry the workpiece after silicon crystal composite treatment.

[0021] Specifically, this invention skips the water washing step after silicon crystal composite treatment and proceeds directly to the drying stage, avoiding erosion and damage to the film layer. Furthermore, the dried film layer of this invention exhibits strong adhesion, excellent resistance to high and low temperatures, and superior corrosion resistance.

[0022] As an optional embodiment of the present invention, the silicon crystal resist comprises the following components, based on the mass of the silicon crystal resist: 5-10% (e.g., 6%, 7%, 8%, 9%) of terminal amino silane coupling agent, 5-10% (e.g., 6%, 7%, 8%, 9%) of terminal epoxy silane coupling agent, 3-7% (e.g., 4%, 5%, 6%) of block copolymer, 10-18% (e.g., 11%, 12%, 13%, 14%, 15%, 16%, 17%) of waterborne polyurethane containing dynamic disulfide bonds, 4-10% (e.g., 5%, 6%, 7%, 8%) of modified nano-silica, 2-6% (e.g., 3%, 4%, 5%) of polyaniline conductive polymer, 1-3% (e.g., 1.5%, 2%, 2.5%) of corrosion inhibitor, and the remainder is water.

[0023] Specifically, this invention utilizes the competitive adsorption and ordered self-assembly of two different terminal silanes (terminated amino silane and terminal epoxy silane) on a metal surface, combined with block copolymers as structure directing agents, to induce the formation of a vertical gradient phase separation structure at the interface: the bottom layer is mainly composed of MO-Si covalent bonds, which are firmly bonded to the metal matrix and provide strong adhesion; the middle layer forms a high-density covalent cross-linked region through the chemical reaction of amino and epoxy groups, which constitutes the mechanical support framework of the film; the surface layer is enriched with dynamic disulfide bond polyurethane, which endows the film with excellent flexibility, weather resistance and self-healing function.

[0024] Furthermore, when microcracks are generated in the film due to external forces or environmental factors, the disulfide bonds (SS) in the surface layer undergo reversible exchange reactions under external stimuli such as heat, light or mechanical stress, causing the molecular chains to rearrange and close the cracks, thereby achieving self-repair of the film layer, effectively inhibiting corrosion from spreading from the defects, and significantly extending the protection life.

[0025] This invention, through the synergistic effect of aminosilane and epoxysilane, not only significantly improves the cohesive density of the film, but also achieves a controllable gradient distribution of components in the vertical direction under the induction of block copolymers, which is impossible for a single silane system. At the same time, the dynamic disulfide bonds on the surface and the mercapto-modified nano-silica form a dynamic cross-linking network through a reversible exchange reaction, giving the film both high density and good toughness. Thus, it can maintain structural integrity even under extreme high and low temperature alternating environments, and its high and low temperature impact resistance is significantly better than that of traditional corrosion inhibitors.

[0026] Furthermore, the polyaniline conductive polymer can form a passivation film on the metal surface, and the corrosion inhibitor can be adsorbed on the metal surface to form a molecular-level protective layer, which enhances the density and repair ability of the passivation film.

[0027] Furthermore, the conductive network of the polyaniline conductive polymer complements the multi-layer barrier of the gradient structure: physical shielding blocks most corrosive media, while electrochemical passivation treatment breaks through the physical barrier to allow trace penetration, achieving a dual guarantee of "passive protection + active inhibition".

[0028] Furthermore, while the corrosion inhibitor provides adsorption protection, the disulfide bonds undergo a reversible exchange reaction under the stimulation of heat, light, or mechanical stress, closing the microcracks in the film layer and achieving long-term self-repair. The corrosion inhibitor can buy time for dynamic repair, and the dynamic repair of the disulfide bonds protects the corrosion inhibitor adsorption layer from mechanical damage.

[0029] In summary, the silicon resist provided by this invention constructs a multi-dimensional, multi-layered synergistic protection system, achieving comprehensive protection of the metal substrate through the organic integration of four core mechanisms: the active passivation of polyaniline and the molecular adsorption of the corrosion inhibitor complement each other at the electrochemical and chemical levels, jointly inhibiting the formation of corrosion microcells; the highly dense physical shielding of the gradient structure provides a stable microenvironment for the passivation effect of polyaniline, while limiting the unnecessary diffusion loss of the corrosion inhibitor; the self-healing function of the dynamic disulfide bonds fills the protection gap of the other three mechanisms after physical damage to the film layer, ensuring that the resist can restore its protective integrity even if it suffers mechanical damage during service. Therefore, this invention achieves full-process, all-dimensional, and long-lasting protection from chemical adsorption, electrochemical passivation, physical shielding to self-healing, significantly superior to the protection modes of traditional resists that rely on a single or simple combination.

[0030] As an optional embodiment of the present invention, the terminal aminosilane coupling agent includes one or more of γ-aminopropyltriethoxysilane, aminopropyltriethoxysilane, and γ-aminopropyltriethoxysilane. The terminal epoxy silane coupling agent includes one or more of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-glycidyl etheroxypropyltrimethoxysilane, and γ-glycidyl etheroxypropyltrimethoxysilane. The block copolymer is PEO-PPO-PEO; The modified nano silica has a particle size of 10-60 nm. The preparation method is as follows: nano silica is impregnated in mercaptosilane coupling agent KH-590 for 1-2 h, and mercapto (-SH) is grafted onto the surface of silica to obtain modified nano silica, which is used to undergo a reversible exchange reaction with the disulfide bonds of waterborne polyurethane. The conductive polymer of polyaniline includes one or more of intrinsic polyaniline, hydrochloric acid-doped polyaniline, and sulfosalicylic acid-doped polyaniline. The corrosion inhibitor is a benzotriazole-based corrosion inhibitor, including one or more of benzotriazole, methylbenzotriazole, and carboxybenzotriazole.

[0031] As an optional embodiment of the present invention, the waterborne polyurethane containing dynamic disulfide bonds, by weight, comprises 30-40 parts of polycarbonate diol (e.g., 32 parts, 34 parts, 36 parts, 38 parts, etc.), 15-20 parts of isophorone diisocyanate (e.g., 16 parts, 17 parts, 18 parts, 19 parts, etc.), 2-5 parts of dithiodiethanol (e.g., 3 parts, 4 parts, etc.), 3-5 parts of dimethylolpropionic acid (e.g., 3.5 parts, 4 parts, 4.5 parts, etc.), 2-4 parts of triethylamine (e.g., 2.5 parts, 3 parts, 3.5 parts, etc.), 0.5-1.5 parts of ethylenediamine (e.g., 0.7 parts, 1 part, 1.3 parts, etc.), and 0.01-0.03 parts of dibutyltin dilaurate (e.g., 0.02 parts, 0.025 parts, etc.).

[0032] As an optional embodiment of the present invention, the method for preparing the aqueous polyurethane containing dynamic disulfide bonds includes the following steps: (1) Polycarbonate diol, isophorone diisocyanate and dibutyltin dilaurate are added to a reaction vessel to carry out a prepolymerization reaction to obtain the first reaction solution; (2) Add dithiodiethanol to the first reaction solution and react to obtain the second reaction solution; (3) Add dimethylolpropionic acid to the second reaction solution to carry out the reaction and obtain the third reaction solution; (4) Cool the third reaction solution to 40°C and add triethylamine for neutralization to obtain the fourth reaction solution; (5) Under high-speed stirring, deionized water is added to the fourth reaction solution in batches to disperse and emulsify, thereby obtaining an emulsified reaction solution; (6) Add ethylenediamine to the emulsion reaction solution and stir to obtain waterborne polyurethane containing dynamic disulfide bonds.

[0033] As an optional embodiment of the present invention, the temperature of the prepolymerization reaction is 80-90°C and the time is 2-3 hours; The reaction temperature in step (2) is 75-85℃ and the reaction time is 1-2h; The reaction temperature in step (3) is 75-85℃ and the time is 1-2h; after adding dimethylolpropionic acid, a small amount of acetone needs to be added to avoid gelation of the system; The neutralization reaction in step (4) is stopped when the pH reaches 7-9; In step (5), the volume ratio of deionized water to the fourth reaction solution is (1-3):(1-3); the emulsification reaction temperature is 25-35℃, and the time is 30-40 min; the high-speed stirring rate is 1500-3000 rpm. In step (6), ethylenediamine is added to the emulsion reaction solution and stirred for 30-40 minutes.

[0034] As an optional embodiment of the present invention, the preparation method of the silicon resist includes the following steps: Add silane hydrolysate to the reactor, slowly add block copolymer solution while stirring, and continue stirring for 10-15 min; then slowly add waterborne polyurethane containing dynamic disulfide bonds, and continue stirring for 10-15 min; further slowly add nano silica dispersion, and continue stirring for 15-25 min, adjust pH to 8.5-9.5, let stand and mature at 25-35℃ for 12-24 h, filter, and obtain silicon crystal resist.

[0035] Specifically, in the preparation of silicon crystal resist, the order of addition follows a hierarchical construction logic of "molecular assembly priority → functional component positioning → nanostructure fixation": First, silane hydrolysis solution is added to allow the terminal amino silane and terminal epoxy silane to undergo controlled hydrolysis in a relatively pure aqueous phase, generating active silanol groups and constructing a basic molecular platform for subsequent ordered assembly; then, block copolymer solution is added, utilizing its amphiphilic structure to form an ordered pre-assembled "silane-copolymer" with hydrolyzed silane through hydrogen bonding and hydrophobic interactions, laying a template for the vertical gradient structure of the film layer; subsequently, waterborne polyurethane containing dynamic disulfide bonds is added, allowing it to be naturally positioned away from the metal interface through selective interaction between hydrophobic segments and the hydrophobic regions of the block copolymer, as well as hydrogen bonding between urethane groups and silane functional groups, creating conditions for enriching the film surface with flexibility and self-healing functions; finally, modified nano silica dispersion is added, utilizing its surface thiol groups and polyurethane disulfide bonds to form a reversible dynamic cross-linking network during subsequent film formation, completing physical cross-linking and performance enhancement without destroying the previous molecular self-assembly structure. This feeding sequence ensures the controllable construction of multi-level structures from the molecular to the nanoscale.

[0036] As an optional embodiment of the present invention, the silane hydrolysate is prepared by mixing an amino-terminated silane coupling agent and an epoxy-terminated silane coupling agent, adding deionized water (20-30% of the total mass of deionized water), and stirring and hydrolyzing at room temperature for 30-60 minutes to obtain the silane hydrolysate. The block copolymer solution is prepared by adding the block copolymer to deionized water (10-20% of the total mass of deionized water), heating to 40-50℃ and stirring to dissolve, and then cooling to room temperature for later use. The nano silica dispersion is prepared by slowly adding modified nano silica into deionized water (30-50% of the total mass of deionized water), and then shearing and dispersing it at a high speed of 2000-3000 rpm until it is uniform. After standing to defoam, it is ready for use. The silicon resist has a pH of 8.5-9.5, a solid content of 12-25%, and a viscosity of 50-200 mPa·s at room temperature.

[0037] As an optional embodiment of the present invention, in step S1, the degreasing treatment includes pre-degreasing and main degreasing, the purpose of which is to thoroughly remove oil, dust and processing residues from the surface of the workpiece, so as to provide a clean metal surface for the uniform film formation of the subsequent silicon crystal resist. The pre-degreasing includes using an alkaline degreasing agent and spraying it at a temperature of 50-60℃ for 3-5 minutes. The main degreasing process includes ultrasonic treatment in an alkaline degreasing agent at a temperature of 55-65℃ for 10-20 minutes, followed by immersion treatment for 5-8 minutes. The alkaline degreasing agent is BONDERITE C-AK 1022R, manufactured by Henkel.

[0038] As an optional embodiment of the present invention, in step S2, the water washing adopts a three-stage countercurrent rinsing process, that is, the workpiece passes through three water washing tanks in sequence, and the water flow direction is opposite to the workpiece movement direction, so as to maximize the cleaning efficiency and save water. Washing time per stage: 1-2 minutes; Water quality for washing: Deionized water or softened water with a conductivity ≤200μS / cm to avoid precipitation reaction between calcium and magnesium ions and silanes.

[0039] Specifically, the purpose of water washing is to thoroughly remove the degreasing agent and emulsified oil residue remaining on the surface of the workpiece after degreasing, so as to prevent the degreasing agent residue from interfering with the subsequent film-forming reaction of the silicon crystal resist.

[0040] As an optional embodiment of the present invention, in step S3, the temperature of the silicon crystal composite treatment is 25-35℃, the treatment time is 3-6 min, and the pH is 8.5-9.5 (e.g., 8.3, 9, 9.3, etc.).

[0041] In an optional embodiment of the present invention, in step S4, the drying process employs an infrared-hot air composite drying process, which is carried out in two stages: First stage (interface preferential curing): Infrared radiation (wavelength 2-4μm), temperature 60-70℃, time 3-5min. Infrared radiation preferentially heats the metal substrate, causing the temperature at the interface to rise first, promoting the preferential formation of MO-Si bonds and enhancing adhesion. The second stage (bulk crosslinking): hot air circulation drying at 80-100℃ for 10-15 minutes. The hot air causes the film to heat up uniformly, completing the epoxy-amino covalent crosslinking, dynamic disulfide bond network construction, and polyaniline oxidation state fixation. After drying, the workpiece is allowed to cool naturally to room temperature to avoid uneven stress release within the film caused by sudden cooling.

[0042] As an optional embodiment of the present invention, the thickness of the dried film layer is 0.5-3 μm.

[0043] This invention can be widely applied to the surface treatment of steel parts (cold-rolled plates, hot-rolled plates), aluminum alloys, copper and copper alloys, stainless steel, etc.

[0044] The present invention will be further described in detail below with reference to specific embodiments and comparative examples. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used, unless otherwise specified, are all commercially available products.

[0045] Example 1

[0046] This embodiment provides a silicon crystal composite processing technology resistant to high and low temperature strong corrosion, including the following steps: S1: The workpiece to be cleaned (Q235 cold-rolled steel plate) is subjected to pre-degreasing and main degreasing in sequence; Pre-degreasing: Using an alkaline degreasing agent (BONDERITE C-AK 1022R, manufactured by Henkel), spray treatment was carried out at a temperature of 55℃ for 4 minutes; The main degreasing process includes ultrasonic treatment for 15 minutes in an alkaline degreasing agent (BONDERITE C-AK 1022R, manufactured by Henkel) at a temperature of 60°C, followed by immersion treatment for 6 minutes. S2: The degreased workpiece is washed with water using a three-stage countercurrent rinsing process; The washing time for each stage is 2 minutes. The washing water is deionized water with a conductivity ≤200μS / cm.

[0047] S3: Immerse the washed workpiece in silicon crystal resist for silicon crystal composite treatment (temperature 30℃, treatment time 4min, pH 9). The silicon crystal resist comprises the following components, based on the mass of the silicon crystal resist: 8% γ-aminopropyltriethoxysilane (KH-550, Nanjing Liansilicon Chemical Co., Ltd.), 8% γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560, Jinjinle Chemical Co., Ltd.), 5% PEO-PPO-PEO (manufacturer: BASF, model: Pluronic F127), 15% waterborne polyurethane containing dynamic disulfide bonds, 6% modified nano-silica, 3% hydrochloric acid-doped polyaniline (Henan Wokais), 2% benzotriazole (Jinan Huifengda Chemical Co., Ltd.), and 53% deionized water.

[0048] The preparation method of modified nano silica includes: impregnating nano silica (model Aerosil® 200) in mercaptosilane coupling agent KH-590 for 1.5 h to obtain modified nano silica; By weight, the waterborne polyurethane containing dynamic disulfide bonds includes 35 parts of polycarbonate diol (Desmophen® CXP 2716, Covestro), 17 parts of isophorone diisocyanate (WANNATE® IPDI, Wanhua Chemical Group Co., Ltd.), 3 parts of dithiodiethanol (Bis(2-hydroxyethyl) Disulfide, TIXIA), 4 parts of dimethylolpropionic acid (DMPA, Hangzhou Jingyou Chemical Co., Ltd.), 3 parts of triethylamine (Nanjing Chemical Reagent Co., Ltd.), 1 part of ethylenediamine (Sinopharm Group), and 0.02 parts of dibutyltin dilaurate (T110630, Aladdin).

[0049] Methods for preparing waterborne polyurethanes containing dynamic disulfide bonds include: (1) Polycarbonate diol, isophorone diisocyanate and dibutyltin dilaurate were added to the reactor for prepolymerization (temperature 85℃, time 2h) to obtain the first reaction solution; (2) Add dithiodiethanol to the first reaction solution and react (at 80°C for 2 hours) to obtain the second reaction solution; (3) Add dimethylolpropionic acid to the second reaction solution and react (at a temperature of 80°C for 2 hours, with a small amount of acetone added) to obtain the third reaction solution; (4) Cool the third reaction solution to 40°C and add triethylamine for neutralization until the pH is 7-9 and the reaction is stopped to obtain the fourth reaction solution; (5) Under high-speed stirring (speed of 2500 rpm), deionized water is added to the fourth reaction solution in batches for dispersion and emulsification (temperature of 30℃, time of 35min) to obtain emulsion reaction solution; The volume ratio of deionized water to the fourth reaction solution is 1:2. (6) Add ethylenediamine to the emulsion reaction solution and stir for 35 min to obtain waterborne polyurethane containing dynamic disulfide bonds.

[0050] Furthermore, the preparation method of the silicon resist includes the following steps: Add silane hydrolysate to the reactor, slowly add block copolymer solution while stirring, and continue stirring for 15 min; then slowly add waterborne polyurethane containing dynamic disulfide bonds, and continue stirring for 15 min; further slowly add nano silica dispersion, and continue stirring for 25 min, adjust pH to 9, let stand and mature at 25℃ for 24 h, filter, and obtain silicon crystal resist.

[0051] The silane hydrolysate is prepared by mixing γ-aminopropyltriethoxysilane and γ-(2,3-epoxypropoxy)propyltrimethoxysilane, adding deionized water (25% of the total mass of deionized water), and stirring and hydrolyzing at room temperature for 60 min to obtain the silane hydrolysate. The block copolymer solution is prepared by adding PEO-PPO-PEO to deionized water (15% of the total mass of deionized water), heating to 50°C and stirring to dissolve, and then cooling to room temperature for later use. The nano silica dispersion is prepared by slowly adding modified nano silica into deionized water (40% of the total mass of deionized water), and then shearing and dispersing it at a high speed of 2500 rpm until uniform. It is then allowed to stand to defoam before use. The silicon resist has a pH of 9, a solid content of 21.4%, and a viscosity of 115 mPa·s at room temperature.

[0052] S4: The workpiece after silicon crystal composite treatment is dried using an infrared-hot air composite drying process. Phase 1: Infrared radiation (wavelength 3μm), temperature 65℃, time 4min; Second stage: Hot air circulation drying, temperature 90℃, time 15min; The dried workpieces are allowed to cool naturally to room temperature.

[0053] Comparative Example 1 The main difference between this comparative example and the embodiment is that PEO-PPO-PEO is not added to the silicon crystal resist. That is, the silicon crystal resist includes the following components: 8% γ-aminopropyltriethoxysilane (KH-550, Nanjing Liansilicon Chemical Co., Ltd.), 8% γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560, Jinjinle Chemical Co., Ltd.), 15% waterborne polyurethane containing dynamic disulfide bonds, 6% modified nano silica, 3% hydrochloric acid-doped polyaniline (Henan Wokais), 2% benzotriazole (Jinan Huifengda Chemical Co., Ltd.), and 58% deionized water.

[0054] The remaining steps and technical parameters are the same as in Example 1.

[0055] Comparative Example 2 The main difference between this comparative example and Example 1 is that the waterborne polyurethane containing dynamic disulfide bonds is replaced with ordinary waterborne polyurethane (Impranil® DLU, Covestro), which does not contain disulfide bonds; the remaining steps and technical parameters are the same as in Example 1.

[0056] Comparative Example 3 The main difference between this comparative example and Example 1 is that hydrochloric acid-doped polyaniline is not added. The silicon resist comprises the following components: 8% γ-aminopropyltriethoxysilane (KH-550, Nanjing Liansilicon Chemical Co., Ltd.), 8% γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560, Jinjinle Chemical Co., Ltd.), 5% PEO-PPO-PEO (manufacturer: BASF, model: Pluronic F127), 15% waterborne polyurethane containing dynamic disulfide bonds, 6% modified nano-silica, 2% benzotriazole (Jinan Huifengda Chemical Co., Ltd.), and 56% deionized water.

[0057] The remaining steps and technical parameters are the same as in Example 1.

[0058] Comparative Example 4 The main difference between this comparative example and Example 1 is that benzotriazole is not added. The silicon resist comprises the following components: 8% γ-aminopropyltriethoxysilane (KH-550, Nanjing Liansilicon Chemical Co., Ltd.), 8% γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560, Jinjinle Chemical Co., Ltd.), 5% PEO-PPO-PEO (manufacturer: BASF, model: Pluronic F127), 15% waterborne polyurethane containing dynamic disulfide bonds, 6% modified nano-silica, 3% hydrochloric acid-doped polyaniline (Henan Wokais), and 55% deionized water.

[0059] The remaining steps and technical parameters are the same as in Example 1.

[0060] Comparative Example 5 The main difference between this comparative example and Example 1 is that, after step S3, a deionized water spray washing step (25°C, spray time 30s) is added, and in step S4, ordinary hot air drying is used, that is, hot air circulation drying at 90°C for 15 minutes. The remaining steps and technical parameters are the same as in Example 1.

[0061] Performance testing Film thickness: Refer to GB / T 13452.2-2008, use an X-ray fluorescence thickness gauge or an eddy current thickness gauge, measure 5 points and take the average value.

[0062] Adhesion: GB / T 9286-2021 (cross-cut test), cross-cut spacing 1mm, 3M 600 tape peel, rating 0-5.

[0063] Neutral salt spray test: GB / T 10125-2021, using 5% NaCl solution, continuous spraying at 35℃, and recording the time when red rust appears.

[0064] High temperature resistance test: GB / T 1735-2009, bake at 250℃ for 2 hours, and observe the blistering, cracking and discoloration of the film layer.

[0065] Low-temperature impact resistance: GB / T 1732-2020 (impact test), after freezing at -40℃ for 1 hour, immediately carry out the impact test with an impact height of 50cm, and observe the cracks.

[0066] Electrochemical impedance spectroscopy: GB / T 40299-2021, using 3.5% NaCl solution, frequency 10. 5 -10 -2 The test was conducted at Hz and an amplitude of 10mV.

[0067] Scratch test after salt spray: GB / T 10125-2021+Scratch, make cross-shaped scratches to the substrate with a blade, and measure the corrosion spread width after 500h of salt spray.

[0068] Appearance of the membrane after salt spray test: GB / T 6461-2002, rating protection level (Rp) and appearance level (Re).

[0069] Salt water immersion test: GB / T 10834-2008, 5% NaCl solution, immerse at room temperature for 7 days, and observe corrosion points and blistering.

[0070] Scratch self-healing ability: Scratch (50μm wide) with a blade, heat-treated at 80℃ for 10min, and the scratch closure rate was observed under a microscope. Closure rate = (initial scratch width - scratch width after repair) / initial scratch width × 100%.

[0071] Membrane flexibility: GB / T 1731-2020 (bending test) Bending around shafts of different diameters (1-6mm) and observing the minimum shaft diameter at which cracks appear.

[0072] High and low temperature cycling resistance: GB / T 2423.22-2012, -40℃ (1h) → room temperature (10min) → 250℃ (1h) → room temperature (10min), 10 cycles.

[0073] Scratch repair after high and low temperature cycling: After 5 cycles of -40℃ to 250℃, the scratch (50μm wide) was repaired at 80℃ for 10min, and the closure rate was observed.

[0074] Contact angle: GB / T 30693-2014, optical contact angle measuring instrument, 5μL water droplet, average value of 3 test points.

[0075] Results data Table 1 Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Film thickness μm 1.8-2.2 1.5-2.0 1.8-2.2 1.8-2.2 1.8-2.2 0.8-1.3 (partially exposed base material) Adhesion Level 0 Level 1 Level 0 Level 0 Level 0 Level 2 Neutral salt spray test (h) 850 550 500 520 620 320 High temperature resistance test (250℃, 2h) No change No change No change No change No change Bubbling, micro-cracks Resistant to low-temperature impact (-40℃) No cracks No cracks microcracks No cracks No cracks Obvious cracks <![CDATA[Electrochemical Impedance Spectroscopy (EIS) |Z| 0. 01 Hz (Ω·cm²)]]> <![CDATA[2.5×10 8 ]]> <![CDATA[3.0×10 7 ]]> <![CDATA[6.0×10 7 ]]> <![CDATA[6.0×10 6 ]]> <![CDATA[1.0×10 8 ]]> <![CDATA[2.0×10 6 ]]> Salt spray test after scratching (mm / 500h) 0.4 2.2 2.8 1.8 1.6 3.5 Appearance of the film after salt spray test Rp10 / Re10 Rp7 / Re8 Rp6 / Re7 Rp6 / Re7 Rp8 / Re8 Rp4 / Re5 Salt water immersion test (5% NaCl, 7 days) No corrosion spots Localized pitting Localized pitting Multiple pitting corrosion Minor pitting Extensive rust Scratch self-healing ability 92% 8% 5% 88% 90% 75% (incomplete membrane layer) Membrane flexibility (bending test) Φ1mm without cracks Φ2mm without cracks Φ3mm microcrack Φ1mm without cracks Φ1mm without cracks Φ4mm crack Scratch repair after high and low temperature cycling 88% 5% 3% 82% 85% 40% Resistant to high and low temperature cycling (-40~250℃) No cracking after 10 tests Microcracks after 6 times Microcracks after 8 times No cracking after 10 tests No cracking after 10 tests Bubbling and cracking occurred after 3 applications. Contact angle (water) 98° 78° 95° 96° 95° 72° As shown in Table 1, compared with Example 1, Comparative Example 1 eliminated the block copolymer Pluronic F127, resulting in the film layer losing its inducing template for the vertical gradient structure. Without the block copolymer, aminosilane and epoxysilane could not form an ordered pre-assembled structure, and the components mixed disorderly during film formation, resulting in a homogeneous structure. This prevented the achievement of a gradient distribution of enriched MO-Si covalent bonds in the bottom layer, a high-density cross-linked region in the middle, and enriched polyurethane on the surface. Consequently, the chemical bonding between the bottom layer and the metal matrix weakened, and the adhesion decreased from grade 0 to grade 1. The lack of enriched flexible polyurethane on the surface reduced the film's hydrophobicity, decreasing the contact angle from 98° to 78°, making it easier for water molecules to penetrate. The physical shielding effect weakened, with the neutral salt spray test time decreasing from 850 hours to 550 hours. Simultaneously, due to the lack of stress buffering from the flexible surface phase, the high and low temperature cycling performance decreased, with microcracks appearing after only 6 cycles.

[0076] As shown in Table 1, compared with Example 1, Comparative Example 2 replaced the waterborne polyurethane containing dynamic disulfide bonds with ordinary waterborne polyurethane (without disulfide bonds), resulting in the loss of the chemical basis for the self-healing function of the film. Dynamic disulfide bonds (SS) can undergo a reversible exchange reaction at room temperature. When microcracks appear in the film, under external thermal stimulation (80°C), the disulfide bonds rearrange, causing the molecular chains to rearrange, thereby achieving crack closure. Ordinary polyurethane does not have this reversible exchange ability, so scratches are almost impossible to repair after heat treatment, and the closure rate drops sharply from 92% to 5%. At the same time, the dynamic crosslinking network between disulfide bonds and mercapto-modified nano-silica is missing, the crosslinking density inside the film is reduced, the flexibility decreases, and the bending test changes from no cracks in Φ1mm to microcracks appearing in Φ3mm; the neutral salt spray test time drops from 850 hours to 500 hours.

[0077] As shown in Table 1, compared with Example 1, Comparative Example 3 eliminated hydrochloric acid-doped polyaniline, resulting in the film losing its electrochemical active passivation capability. Polyaniline, as a conductive polymer, can induce the formation of a dense oxide film at the metal interface through its reversible redox reaction, continuously repairing microscopic defects in the film and forming a significant passivation region. Without polyaniline, the film relies solely on physical shielding and the passive protection of corrosion inhibitors, and the electrochemical impedance spectroscopy shows a low-frequency impedance (|Z| < 0). 01 (Hz) from 2.5×10 8 Ω·cm² decreased to 6×10 6 The Ω·cm² decreased by two orders of magnitude; the neutral salt spray test time decreased from 850 hours to 520 hours; the active repair capability of polyaniline after scratches was lost; multiple pitting corrosions appeared in the salt water immersion test, indicating that the corrosion microcells could not be effectively suppressed.

[0078] As shown in Table 1, compared with Example 1, Comparative Example 4 omitted the benzotriazole corrosion inhibitor, resulting in the loss of the molecular-level adsorption barrier in the film. Benzotriazole corrosion inhibitors can preferentially adsorb onto active sites on the metal surface, forming a dense molecular adsorption layer that fills microscopic defects in the film and effectively prevents direct contact between corrosive media such as water, oxygen, and chloride ions and the metal substrate. Without the corrosion inhibitor, although the film retains its gradient structure and polyaniline passivation, microscopic defects become the preferred initiation points for corrosion; the copper accelerated acetic acid spray test time decreased from ≥168 hours to 72 hours, indicating that the inhibitory effect of benzotriazole on copper ion migration was lost; localized pitting corrosion appeared in the salt water immersion test, and the neutral salt spray test time decreased from 850 hours to 620 hours.

[0079] As shown in Table 1, compared with Example 1, Comparative Example 5 added a water washing process after silicon crystal treatment and changed infrared-hot air composite drying to ordinary hot air drying, resulting in the destruction of the integrity of the film structure and insufficient cross-linking reaction. After silicon crystal treatment, the silane film was not yet cured and was only physically adsorbed onto the metal surface through hydrogen bonds. During water washing, water molecules competed with silane for active sites on the metal surface, hydrolyzing and washing away the adsorbed silane film. At the same time, ordinary hot air drying could not achieve "interface preferential curing", and the film layer was heated simultaneously inside and outside, generating internal stress. Therefore, the film thickness decreased from 1.8-2.2 μm to 0.8-1.3 μm and locally exposed the substrate, and the adhesion dropped from grade 0 to grade 2. Insufficient cross-linking led to poor thermal stability. Bubbling occurred in the 250°C high-temperature test and cracking occurred in the -40°C low-temperature impact test. The neutral salt spray test time dropped sharply from 850 hours to 320 hours. The high and low temperature resistance cycle only lasted for 3 cycles before bubbling and cracking occurred.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A silicon crystal composite processing technology resistant to high and low temperature strong corrosion, characterized in that, Includes the following steps: S1: Degrease the workpiece to be cleaned; S2: Wash the degreased workpiece with water; S3: Immerse the washed workpiece in silicon crystal resist for silicon crystal composite treatment; S4: Dry the workpiece after silicon crystal composite treatment; The silicon crystal resist comprises, by weight, the following components: 5-10% amino-terminated silane coupling agent, 5-10% epoxy-terminated silane coupling agent, 3-7% block copolymer, 10-18% waterborne polyurethane containing dynamic disulfide bonds, 4-10% modified nano-silica, 2-6% polyaniline conductive polymer, 1-3% corrosion inhibitor, and the remainder being water.

2. The silicon crystal composite treatment process resistant to high and low temperature strong corrosion according to claim 1, characterized in that, The terminal aminosilane coupling agent includes one or more of γ-aminopropyltriethoxysilane, aminopropyltriethoxysilane, and γ-aminopropyltriethoxysilane; And / or, the terminal epoxy silane coupling agent includes one or more of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-glycidyl etheroxypropyltrimethoxysilane, and γ-glycidyl etheroxypropyltrimethoxysilane. And / or, the block copolymer is PEO-PPO-PEO; And / or, the particle size of the modified nano silica is 10-60 nm, and its preparation method is as follows: impregnate nano silica in mercaptosilane coupling agent KH-590 for 1-2 h to obtain modified nano silica; And / or, the polyaniline conductive polymer includes one or more of intrinsic polyaniline, hydrochloric acid-doped polyaniline, and sulfosalicylic acid-doped polyaniline; And / or, the corrosion inhibitor is a benzotriazole corrosion inhibitor, including one or more of benzotriazole, methylbenzotriazole, and carboxybenzotriazole.

3. The silicon crystal composite treatment process resistant to high and low temperature strong corrosion according to claim 1, characterized in that, By mass fraction, the waterborne polyurethane containing dynamic disulfide bonds includes 30-40 parts of polycarbonate diol, 15-20 parts of isophorone diisocyanate, 2-5 parts of dithiodiethanol, 3-5 parts of dimethylolpropionic acid, 2-4 parts of triethylamine, 0.5-1.5 parts of ethylenediamine, and 0.01-0.03 parts of dibutyltin dilaurate.

4. The silicon crystal composite treatment process resistant to high and low temperature strong corrosion according to claim 3, characterized in that, The preparation method of the aqueous polyurethane containing dynamic disulfide bonds includes the following steps: (1) Polycarbonate diol, isophorone diisocyanate and dibutyltin dilaurate are added to a reaction vessel to carry out a prepolymerization reaction to obtain the first reaction solution; (2) Add dithiodiethanol to the first reaction solution and react to obtain the second reaction solution; (3) Add dimethylolpropionic acid to the second reaction solution to carry out the reaction and obtain the third reaction solution; (4) Cool the third reaction solution to 40°C and add triethylamine for neutralization to obtain the fourth reaction solution; (5) Under high-speed stirring, deionized water is added to the fourth reaction solution in batches to disperse and emulsify, thereby obtaining an emulsified reaction solution; (6) Add ethylenediamine to the emulsion reaction solution and stir to obtain waterborne polyurethane containing dynamic disulfide bonds.

5. The silicon crystal composite treatment process resistant to high and low temperature strong corrosion according to claim 4, characterized in that, The prepolymerization reaction is carried out at a temperature of 80-90℃ for 2-3 hours. And / or, the reaction temperature in step (2) is 75-85℃ and the time is 1-2h; And / or, the reaction temperature in step (3) is 75-85℃ and the time is 1-2h; And / or, the neutralization reaction in step (4) is stopped when the pH reaches 7-9; And / or, in step (5), the volume ratio of deionized water to the fourth reaction solution is (1-3):(1-3); the emulsification reaction temperature is 25-35℃, the time is 30-40min; the high-speed stirring rate is 1500-3000 rpm; And / or, in step (6), ethylenediamine is added to the emulsion reaction solution and stirred for 30-40 minutes.

6. The silicon crystal composite treatment process resistant to high and low temperature strong corrosion according to claim 1, characterized in that, The preparation method of the silicon resist includes the following steps: Add silane hydrolysate to the reactor, slowly add block copolymer solution while stirring, and continue stirring for 10-15 min; then slowly add waterborne polyurethane containing dynamic disulfide bonds, and continue stirring for 10-15 min; further slowly add nano silica dispersion, and continue stirring for 15-25 min, adjust pH to 8.5-9.5, let stand and mature at 25-35℃ for 12-24 h, filter, and obtain silicon crystal resist.

7. The silicon crystal composite treatment process resistant to high and low temperature strong corrosion according to claim 6, characterized in that, The silane hydrolysate is prepared by mixing an amino-terminated silane coupling agent with an epoxy-terminated silane coupling agent, adding deionized water, and stirring and hydrolyzing at room temperature for 30-60 minutes. And / or, the block copolymer solution is prepared by adding the block copolymer to deionized water, heating to 40-50°C and stirring to dissolve, and then cooling to room temperature for later use; And / or, the nano silica dispersion is prepared by slowly adding modified nano silica to deionized water, shearing and dispersing it at a high speed of 2000-3000 rpm until uniform, and then allowing it to stand to defoam before use. And / or, the silicon resist has a pH of 8.5-9.5, a solid content of 12-25%, and a viscosity of 50-200 mPa·s at room temperature.

8. The silicon crystal composite treatment process resistant to high and low temperature strong corrosion according to claim 1, characterized in that, In step S1, the degreasing process includes pre-degreasing and main degreasing; The pre-degreasing includes using an alkaline degreasing agent and spraying it at a temperature of 50-60℃ for 3-5 minutes. The main degreasing process includes ultrasonic treatment in an alkaline degreasing agent at a temperature of 55-65℃ for 10-20 minutes, followed by immersion treatment for 5-8 minutes.

9. The silicon crystal composite treatment process resistant to high and low temperature strong corrosion according to claim 1, characterized in that, In step S2, the water washing adopts a three-stage countercurrent rinsing process; Washing time per stage: 1-2 minutes; Water quality for washing: Deionized water or softened water, conductivity ≤200μS / cm; And / or, in step S3, the temperature of the silicon crystal composite treatment is 25-35℃, the treatment time is 3-6 min, and the pH is 8.5-9.

5.

10. The silicon crystal composite treatment process resistant to high and low temperature strong corrosion according to claim 1, characterized in that, The drying process employs an infrared-hot air composite drying technology, which is carried out in two stages: Phase 1: Infrared radiation, wavelength 2-4μm, temperature 60-70℃, time 3-5min; Second stage: Hot air circulation drying, temperature 80-100℃, time 10-15min; And / or, the thickness of the dried film is 0.5-3 μm.