A method for preparing a slow-release hydrochloric acid dry film for preventing oxidation of a metal surface
By spraying a slow-release hydrochloric acid dry film prepared from polyvinyl butyral and chloral hydrate onto the surface of a pickled metal plate, the problem of diffusion bonding affected by the oxide layer on the oxygen-loving metal surface was solved, achieving effective protection and extending the production time window.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- AVIC BEIJING AERONAUTICAL MFG TECH RES INST
- Filing Date
- 2026-04-02
- Publication Date
- 2026-07-10
AI Technical Summary
Oxyphilic metal surfaces develop an oxide layer after pickling, which affects the diffusion bonding quality. The short time window for this process leads to unstable diffusion quality during production.
A slow-release hydrochloric acid dry film was prepared using polyvinyl butyral and chloral hydrate, and sprayed onto the surface of a pickled metal plate to form a dense protective coating, preventing the metal surface from contacting air. The chloral hydrate slowly releases hydrochloric acid to prevent oxidation.
It effectively prevents secondary oxidation of metal surfaces, extends the gap time of metal sheets, ensures diffusion bonding quality, and the coating is easy to peel off without residue.
Smart Images
Figure CN122352525A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of metal surface oxidation technology, and more specifically to a method for preparing a slow-release hydrochloric acid dry film for preventing metal surface oxidation. Background Technology
[0002] Oxyphilic metals, due to their reactive chemical properties, form an oxide film when exposed to air, which fails to protect the base material and negatively impacts weld quality. Pickling of sheet metal is a crucial step in superplastic forming / diffusion bonding, primarily aimed at removing oxide layers, oil, and other contaminants from the metal surface to facilitate subsequent superplastic forming / diffusion bonding. For oxygen-loving metals, subsequent processes should be carried out immediately after pickling. If the metal is not used immediately after pickling and deionized water rust removal, it will undergo secondary oxidation after being stored in the air for a period of time. This means that pickling and subsequent processes on the metal plate surface must be carried out within a very short time window. In production practice, the long interval between pickling and subsequent processes often leads to the formation of a new oxide layer on the metal surface, which affects the diffusion quality.
[0003] Therefore, the inventors have provided a method for preparing a slow-release hydrochloric acid dry film to prevent oxidation of metal surfaces. Summary of the Invention
[0004] (1) Technical problems to be solved This invention provides a method for preparing a slow-release hydrochloric acid dry film to prevent oxidation of metal surfaces, solving the technical problem that the formation of an oxide layer on oxyphilic metal surfaces affects the diffusion bonding quality.
[0005] (2) Technical solution This invention provides a method for preparing a slow-release hydrochloric acid dry film to prevent oxidation of metal surfaces, comprising the following steps: Dissolve polyvinyl butyral in anhydrous ethanol to form a homogeneous and transparent solution; Add chloral hydrate and a rheology modifier to the homogeneous and transparent solution to obtain a coating solution for preparing a sustained-release hydrochloric acid coating. The coating solution is sprayed onto the surface of the pickled metal plate. During the natural placement process, the ethanol evaporates naturally to form a slow-release hydrochloric acid dry film.
[0006] Furthermore, the polyvinyl butyral dissolves in anhydrous ethanol at a temperature of 40–80°C.
[0007] Furthermore, the outflow time of the polyvinyl butyral was measured to be 80–120 s using a Chaien cup.
[0008] Furthermore, the effluent time of the polyvinyl butyral is 100s.
[0009] Furthermore, the Chain Cup is a No. 4 cup.
[0010] Furthermore, the polyvinyl alcohol in the homogeneous transparent solution is 10-15% by mass.
[0011] Furthermore, the hydrated chloral in the coating solution has a mass percentage of 2-25%.
[0012] Furthermore, the rheology modifier is present in the coating liquid at a mass percentage of 1-5%.
[0013] Furthermore, the ambient temperature for natural placement is 20–40°C.
[0014] Furthermore, the natural placement time is greater than 6 hours.
[0015] (3) Beneficial effects In summary, this invention utilizes the principles of polyvinyl butyral's easy film formation and chloral hydrate's easy release of hydrochloric acid. After pickling the metal sheet, a coating liquid containing slow-release HCl is sprayed onto it, forming a dense protective coating. Because of the presence of the coating liquid on the metal sheet surface, the pickled sheet is prevented from contacting air, thus protecting the oxygen-loving sheet from secondary oxidation and effectively extending the shelf life of the sheet. Attached Figure Description
[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0017] Figure 1 This is a schematic flowchart of a method for preparing a slow-release hydrochloric acid dry film for preventing oxidation of metal surfaces, provided in an embodiment of the present invention. Detailed Implementation
[0018] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present invention by way of example, but should not be used to limit the scope of the present invention, that is, the present invention is not limited to the described embodiments.
[0019] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.
[0020] Figure 1 This is a schematic flowchart of a method for preparing a slow-release hydrochloric acid dry film for preventing metal surface oxidation, as provided in an embodiment of the present invention. Figure 1 As shown, the method may include the following steps: S100. Dissolve polyvinyl butyral in anhydrous ethanol to form a homogeneous and transparent solution.
[0021] Specifically, the dissolution temperature of polyvinyl butyral in anhydrous ethanol is 40–80°C, and the eluent flow time of polyvinyl butyral, measured using a Chain cup, is 80–120 s, with a flow time of 100 s. Furthermore, a No. 4 Chain cup is used, and the mass percentage of polyvinyl alcohol in the homogeneous, transparent solution is 10–15%.
[0022] S200. Add hydrated chloral and rheology modifier to a uniform transparent solution to obtain a coating solution for preparing a slow-release hydrochloric acid coating.
[0023] Specifically, the mass percentage of chloral hydrate in the coating solution is 2-25%, and the mass percentage of rheology modifier in the coating solution is 1-5%.
[0024] S300. The coating liquid is sprayed onto the surface of the pickled metal plate. During the natural placement process, the ethanol evaporates naturally to form a slow-release hydrochloric acid dry film.
[0025] Specifically, the presence of a coating liquid on the surface of the metal sheet prevents the pickled sheet from coming into contact with air. Even if oxidation occurs, the oxidation products, rust spots, and rust marks will be removed by the slow-released HCl in the coating. The polyvinyl butyral in the wet and semi-wet coatings has a glue-like stickiness, which will adhere the oxides to the coating and remove them from the metal surface.
[0026] As an optional implementation method, the ambient temperature for natural placement is 20–40°C. However, excessively high storage or drying temperatures will cause the hydrated chloral in the coating solution to decompose into hydrochloric acid (HCl) too quickly, depleting the hydrated chloral in the coating and causing it to lose its ability to release HCl slowly.
[0027] As an optional implementation, the natural placement time is greater than 6 hours. Specifically, since the solvent for the liquid coating is ethanol, which is easily volatile, a semi-wet film will form after 8 hours at room temperature. Once formed, the film is easily peeled off from the metal sheet surface. Even after a longer placement period, when the coating becomes a solid dry film, it still has the function of slowly releasing HCl to remove the oxide layer and rust spots from the metal sheet surface. The dried solid film is also easily peeled off from the metal sheet surface. After rinsing or wiping with deionized water, the sheet can be sealed and welded.
[0028] Coating liquid parts and application scenarios It should be noted that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. The present invention is not limited to the specific steps and structures described above and shown in the figures. Furthermore, for the sake of brevity, detailed descriptions of known methods and techniques are omitted here.
[0029] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art without departing from the scope of the invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this application should be included within the scope of the claims of this application.
Claims
1. A method for preparing a slow-release hydrochloric acid dry film for preventing oxidation of metal surfaces, characterized in that, The method includes the following steps: Dissolve polyvinyl butyral in anhydrous ethanol to form a homogeneous and transparent solution; Add chloral hydrate and a rheology modifier to the homogeneous and transparent solution to obtain a coating solution for preparing a sustained-release hydrochloric acid coating. The coating solution is sprayed onto the surface of the pickled metal plate. During the natural placement process, the ethanol evaporates naturally to form a slow-release hydrochloric acid dry film.
2. The method for preparing a slow-release hydrochloric acid dry film for preventing metal surface oxidation according to claim 1, characterized in that, The polyvinyl butyral dissolves in anhydrous ethanol at a temperature of 40–80°C.
3. The method for preparing a slow-release hydrochloric acid dry film for preventing metal surface oxidation according to claim 1, characterized in that, The efflux time of the polyvinyl butyral was measured to be 80–120 s using a Chaien cup.
4. The method for preparing a slow-release hydrochloric acid dry film for preventing metal surface oxidation according to claim 3, characterized in that, The efflux time of the polyvinyl butyral is 100s.
5. The method for preparing a slow-release hydrochloric acid dry film for preventing metal surface oxidation according to claim 3, characterized in that, The Chain Cup mentioned is a No. 4 cup.
6. The method for preparing a slow-release hydrochloric acid dry film for preventing metal surface oxidation according to claim 1, characterized in that, The polyvinyl alcohol in the homogeneous transparent solution is 10-15% by mass.
7. The method for preparing a slow-release hydrochloric acid dry film for preventing metal surface oxidation according to claim 1, characterized in that, The hydrated chloral in the coating solution has a mass percentage of 2-25%.
8. The method for preparing a slow-release hydrochloric acid dry film for preventing metal surface oxidation according to claim 1, characterized in that, The rheology modifier is present in the coating liquid at a mass percentage of 1-5%.
9. The method for preparing a slow-release hydrochloric acid dry film for preventing metal surface oxidation according to claim 1, characterized in that, The ambient temperature for natural placement is 20–40℃.
10. The method for preparing a slow-release hydrochloric acid dry film for preventing metal surface oxidation according to claim 1 or 9, characterized in that, The natural placement time is more than 6 hours.