A coating and its application in improving cupping performance of TA1 pure titanium sheet

Abstract

This invention relates to the field of non-ferrous metal sheet forming technology. The invention discloses a coating and its application in improving the cupping properties of TA1 pure titanium sheets. The coating comprises the following components by weight fraction: 50-60 wt% epoxy resin, 15-20 wt% polyamide curing agent, 5-8 wt% nano-silica particles, 10-15 wt% toughening agent, 3-5 wt% graphite powder, and 2-3 wt% silane coupling agent. By spraying the coating onto TA1 pure titanium sheets, the cupping properties of the TA1 pure titanium sheets can be improved. The improvement in cupping properties (IE value) is not only greater than 0.5 mm but can also be greater than 1.5 mm. Compared with traditional methods of improving materials and heat treatment processes, this invention is not only simple to operate but also has excellent results, demonstrating significant progress.

Description

Technical Field

[0001] This invention relates to the field of non-ferrous metal sheet forming technology, specifically to a coating and its application in improving the cupping performance of TA1 pure titanium sheets. Background Technology

[0002] The statements in this section provide only background information relevant to the disclosure of this application and may not constitute prior art.

[0003] TA1 pure titanium sheet is widely used in precision-formed parts due to its low density, high specific strength, and excellent corrosion resistance. However, its cupping performance (i.e., Eriksen cupping value, IE value) is limited by the material's inherent plasticity and stress concentration during deformation. In complex forming processes such as deep drawing and bending, it is prone to cracking or localized thinning, which restricts its application in high-deformation scenarios. Therefore, developing a method to improve the stamping performance of pure titanium sheet has significant economic and social benefits.

[0004] Traditional methods to improve the cupping properties of TA1 pure titanium sheets mainly include: (1) Composition optimization: improving plasticity by reducing the content of interstitial impurities such as oxygen and nitrogen (e.g., controlling the oxygen content below 0.15%), but significantly increasing production costs, for example, patents with publication numbers CN114395712B and CN103409642B; (2) Heat treatment process: annealing at 800-900℃ to eliminate internal stress, but only slightly improving the IE value (usually ≤0.5mm); for example, patent with publication number CN118635269A; (3) Lubrication condition optimization: changing the stress distribution by improving the lubrication state between the mold and the sheet. However, relying solely on lubrication is insufficient to fundamentally solve the problem of insufficient intrinsic plasticity of the material.

[0005] In recent years, surface engineering technology has provided new solutions to the aforementioned problems. However, it has not explicitly addressed how to improve the cupping properties of pure titanium sheets. Existing technologies only mention coating Ti65 titanium alloy sheets with a NiCrAlSiY coating, which, after cyclic oxidation, maintains a tensile strength retention rate of over 90%, and the tensile elongation of the coated sheet can reach about 30% of the initial elongation. Another existing technology involves surface oxidation of titanium sheets to form an oxide film (Ti6O) on the titanium alloy surface, achieving a maximum elongation of 31.845% and exhibiting excellent strength-plasticity compatibility. However, both of these studies focus on titanium alloy sheets, not pure titanium sheets; furthermore, the parameters measured are the ultimate deformation capacity under uniaxial tensile stress, which cannot directly reflect the cupping properties of the material under biaxial tensile stress (such as stamping or bulging). Summary of the Invention

[0006] The purpose of this invention is to address the problem that it is difficult to improve the cupping performance of pure titanium thin plates, and to provide a coating and its application in improving the cupping performance of TA1 pure titanium thin plates. By optimizing the coating formulation and process parameters, the elastic buffering and interfacial strengthening effects of the coating are utilized to significantly improve the plastic deformation capacity of titanium materials.

[0007] The technical solution of the present invention is as follows: This invention provides a coating for improving the cupping properties of TA1 pure titanium thin plates, comprising the following components in the indicated weight proportions: Epoxy resin 50-60wt%, polyamide curing agent 15-20wt%, nano silica particles 5-8wt% (particle size 50nm), toughening agent 10-15wt%, graphite powder 3-5wt%, silane coupling agent 2-3wt%.

[0008] Preferably, the particle size of the nano-silica particles is 50 nm.

[0009] Preferably, the toughening agent is carboxyl-terminated butadiene-acrylonitrile rubber.

[0010] Preferably, the particle size of the graphite powder is 2-3 μm.

[0011] In another aspect, the present invention provides the application of a coating for improving the cupping properties of TA1 pure titanium thin plates as described above in improving the cupping properties of TA1 pure titanium thin plates.

[0012] Another aspect of the present invention provides a method for improving the cupping properties of TA1 pure titanium thin plates, comprising the following steps: A coating as described above to improve the cupping performance of TA1 pure titanium sheet is sprayed onto one side of the sheet. The coating thickness is 30μm-50μm. The sheet is left to air dry naturally for 1-2 hours until the coating is surface dry and non-sticky, but not completely brittle.

[0013] Preferably, the spraying is electrostatic spraying or conventional spray gun spraying.

[0014] The principle of the process of this invention: Nanoparticle reinforcement and toughening agent modification of paint improve coating elasticity and suppress stress concentration; the micron-level rough surface (Ra=1.5-2.0μm) of TA1 pure titanium itself enhances the mechanical anchoring effect, and interface strengthening and coupling agent modification make the coating adhesion ≥5MPa (cross-cut test) to ensure that the coating does not fall off during deformation.

[0015] Compared with existing technologies, the advantages of this invention are: 1. Significantly improved cupping performance: After treatment with this method, the IE value of TA1 pure titanium sheet can be increased by 0.5-1.6mm, and the crack resistance is improved; 2. Low process cost: Compared with technologies such as vacuum coating, spray painting equipment requires less investment and has a higher utilization rate of coating materials; 3. Wide range of applications: It is compatible with TA1 thin plates with a thickness of 0.5 mm to 1.5 mm, and has no adverse effect on subsequent welding and assembly, and does not require changes to the composition of TA1 base material or heat treatment process. Detailed Implementation

[0016] The specific embodiments listed in this invention are merely examples, and the invention is not limited to the specific embodiments described below. For those skilled in the art, any equivalent modifications and substitutions to the embodiments described below are also within the scope of this invention. Therefore, all equivalent transformations and modifications made without departing from the spirit and scope of this invention should be covered within its scope. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. All reagents or instruments whose manufacturers are not specified are commercially available conventional products. To better illustrate this invention, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that this invention can be practiced even without certain specific details. In other embodiments, methods, means, equipment, and steps well known to those skilled in the art are not described in detail in order to highlight the main points of this invention.

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art. Unless otherwise specified, all units used in this specification are International Standard Units (SI), and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors unavoidable in industrial production.

[0018] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0019] Example 1 1.0mm TA1 pure titanium sheet purchased from the market was selected.

[0020] Follow these steps: (1) Cut TA1 pure titanium sheets into blanks of the required size for the cupping test, a total of 6 pieces; (2) Substrate degreasing treatment: Use anhydrous ethanol to ultrasonically clean the oil stains on the surface of TA1 thin plate at 30W / L for 10-15 minutes to remove impurities and improve coating adhesion. (3) Take 3 pieces for painting treatment; use electrostatic spraying to spray the coating of this application, and spray a coating with a thickness of 50μm. The coating formula is: epoxy resin 55wt%, polyamide curing agent 20wt%, nano silica particles 8wt%, carboxyl-terminated nitrile rubber 10wt%, graphite powder 5wt%, and silane coupling agent 2wt%.

[0021] After spraying, allow the coating to air dry naturally until it is surface dry and non-sticky, but not completely brittle, approximately 1-2 hours. Within 4 hours after spraying, conduct a cupping test on a BUP1000 forming tester according to GB / T4156-2020 "Erikson Cupping Test for Thin Sheets and Strips of Metallic Materials". The painted side is facing upwards, and the contact surface with the punch is unpainted. Vaseline lubricant is used, the punch speed is 6 mm / min, and the blank holder force is 10 kN. Record the cupping value (IE value) and the degree of coating cracking. In this example, the experiment was conducted 2 hours after spraying. Six test samples were tested with identical parameters. The difference in the mean IE cupping values ​​of three TA1 original sheet samples and three samples with surface paint treatment was compared.

[0022] The results are shown in the table below:

[0023] As can be seen from the table, the stamping performance of the TA1 pure titanium sheet in Example 1 was significantly improved after surface painting, with an average cupping increase of 1.59 mm.

[0024] Example 2 0.6mm TA1 pure titanium sheet purchased from the market was selected.

[0025] Follow these steps: (1) Cut TA1 pure titanium sheets into blanks of the required size for the cupping test, a total of 6 pieces; (2) Substrate degreasing treatment: Use anhydrous ethanol to ultrasonically clean the oil stains on the surface of TA1 thin plate at 30W / L for 10-15 minutes to remove impurities and improve coating adhesion. (3) Take 3 pieces and spray paint them; use electrostatic spraying to spray the same formula coating as in Example 1 and spray a 40μm coating.

[0026] Using the same test method as in Example 1, the differences in the mean IE cupping values ​​of 3 original TA1 plates and 3 plates with surface paint treatment were compared.

[0027]

[0028] As can be seen from the table, after the TA1 pure titanium sheet in Example 2 was treated with surface painting, its stamping performance was significantly improved, with an average cupping increase of 0.84 mm.

[0029] Example 3 0.5mm TA1 pure titanium sheet purchased from the market was selected.

[0030] Follow these steps: (1) Cut TA1 pure titanium sheets into blanks of the required size for the cupping test, a total of 6 pieces; (2) Degreasing treatment of substrate: Use anhydrous ethanol 30W / L to ultrasonically clean the oil stains on the surface of TA1 thin plate for 10-15 minutes to remove impurities and improve coating adhesion. (3) Take 3 pieces and spray paint them; use electrostatic spraying with the same formula paint as in Example 1 and spray a 30μm coating.

[0031] Using the same test method as in Example 1, the differences in the mean IE cupping values ​​of 3 original TA1 plates and 3 plates with surface paint treatment were compared.

[0032]

[0033] As can be seen from the table, after the TA1 pure titanium sheet in Example 3 was treated with surface painting, its stamping performance was significantly improved, with an average cupping increase of 0.66 mm.

[0034] As can be seen from the results of the embodiments described above, the coating of this application improves the IE value of TA1 pure titanium thin plates by more than 0.5 mm. Compared with the traditional complex thermal optimization operation, this application is not only simple to operate, but also has a very significant effect on improving the IE value of TA1 pure titanium thin plates. In Example 1, for a 1 mm thick TA1 pure titanium thin plate, the IE value is improved by 1.59 mm, which is 3 times more efficient than the traditional thermal optimization method, showing significant progress.

[0035] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed and specific, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the technical solution of this application, and these modifications and improvements all fall within the scope of protection of this application.

Claims

1. A coating for improving the cupping properties of TA1 pure titanium thin plates, characterized in that, The coating comprises the following components by weight fraction: The composition includes 50-60 wt% epoxy resin, 15-20 wt% polyamide curing agent, 5-8 wt% nano-silica particles, 10-15 wt% toughening agent, 3-5 wt% graphite powder, and 2-3 wt% silane coupling agent.

2. The coating for improving the cupping properties of TA1 pure titanium thin plates according to claim 1, characterized in that, The particle size of the nano-silica particles is 50 nm.

3. The coating for improving the cupping properties of TA1 pure titanium thin plates according to claim 1, characterized in that, The toughening agent is carboxyl-terminated butadiene-acrylonitrile rubber.

4. The coating for improving the cupping properties of TA1 pure titanium thin plates according to claim 1, characterized in that, The graphite micro powder has a particle size of 2-3 μm.

5. The application of the coating for improving the cupping properties of TA1 pure titanium thin plates as described in any one of claims 1-4 in improving the cupping properties of TA1 pure titanium thin plates.

6. A method for improving the cupping properties of TA1 pure titanium thin plates, comprising the following steps: A coating for improving the cupping properties of TA1 pure titanium sheet as described in any one of claims 1-4 is sprayed onto one side of the sheet. The coating thickness is 30μm-50μm. The sheet is left to air dry naturally until it is surface dry and non-sticky, but not completely brittle.

7. A method for improving the cupping properties of TA1 pure titanium thin plates according to claim 6, characterized in that, The thickness of the TA1 pure titanium sheet is 0.5-1.5 mm.

8. A method for improving the cupping properties of TA1 pure titanium thin plates according to claim 6, characterized in that, The spraying is either electrostatic spraying or conventional spray gun spraying.

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