A heat-resistant base oxide film and preparation method thereof

Abstract

The present invention belongs to the technical field of electrolytic production processes for coatings, and relates to a heat-resistant base oxide film and a method for preparing the same. In response to the technical problem in the prior art that the oxide film on the base of PECVD equipment is excessively large or small in pore size and micropore density during the generation or regeneration process, resulting in poor heat resistance and easy detachment from the base, thus affecting its service life, the present application provides a method for preparing a heat-resistant base oxide film, which improves the oxide film structure and enhances its flexibility, thereby reducing the tensile stress between the oxide film and the base material during continuous heating and cooling. The prepared oxide film is not easily cracked under high-temperature impact, has significantly improved heat resistance, and significantly enhanced heat shock resistance, thus meeting the performance requirements.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrolytic production technology of coatings, and in particular relates to a heat-resistant base oxide film and a preparation method thereof. Background Art

[0002] LCD (Liquid Crystal Display) is the abbreviation of liquid crystal display. TFT-LCD (Thin Film Transistor Liquid Crystal Display) technology is a technology that cleverly combines microelectronics technology with liquid crystal display technology. The technology of fine microelectronics processing on single crystals is transplanted to the processing of thin film transistor (TFT) arrays on large-area glass. The array substrate is then combined with another substrate with a color filter film, using the already mature liquid crystal display (LCD) technology to form a liquid crystal box. After subsequent processes such as polarizer lamination, the liquid crystal display device is finally formed. The manufacturing process of TFT-LCD is diverse, among which PECVD (Plasma Enhanced Chemical Vapor Deposition) is the key step. When high-speed electrons in the plasma collide with neutral reactive gas molecules, the neutral reactive gas molecules will be broken into fragments or activated to be easily reactive. The substrate temperature is usually maintained at around 350°C to obtain a good SiOx or SiNx film, which can be used as the final passivation protective layer of the integrated circuit to improve the reliability of the integrated circuit. The deposition equipment used is mainly for film formation on glass substrates. For example Figure 1 As shown, a PECVD system consists of various chambers, each filled with CVD parts. These components primarily include the susceptor (SS), diffuser (DF), and backing plate (BP), each serving a specific purpose. The susceptor, a key component in the chamber, supports the glass substrate, while its base metal also houses embedded electric heating elements that heat the chamber according to the process temperature (300-450°C). The uniformity of the susceptor's heating temperature, flatness, roughness, and surface thickness are key factors influencing the quality of chemical vapor deposition films. During maintenance, the susceptor undergoes anodization, forming a thin aluminum oxide film on its surface to enhance its insulation, corrosion resistance, and wear resistance.

[0003] The aluminum oxide film commonly used in the industry is anodized with an electrolyte to form an oxide film on the surface of the base. The oxide film consists of two structures, such as Figure 2As shown, the bottom is a dense barrier-type Al2O3 with a thickness of only tens of nanometers, and above the barrier film is a porous Al2O3. Generally speaking, the thickness of the oxide film refers to the thickness of the porous layer. The oxide film has good adsorption properties and can adsorb tiny particles, as well as corrosion resistance and heat resistance. The outer layer of the porous layer of the oxide film is composed of a mixture of hydrated oxide and γ-Al2O3 or monohydrated oxide and transition oxide, while the inner layer of the porous layer is amorphous. Since the base needs to maintain a high temperature of 350~400℃ in the chamber, the service life is often more than one year and the chamber needs to be switched frequently for equipment replacement. During the frequent heating and cooling process, the oxide film is continuously subjected to thermal shock. Since the thermal expansion coefficient of aluminum alloy is higher than that of the oxide film on its surface, tensile stress will be generated in the oxide film during the heating process. As shown Figure 3-5 As shown, when the tensile stress within the film exceeds its tensile strength, critical cracking occurs, causing the oxide film to fall off and fall into the cavity, resulting in poor glass particle quality. Particle quality is the primary factor affecting CVD process yield. Table 1 shows the composition of the falling particles. SEM-EDS analysis shows that the crystals falling off the surface are Al2O3. Therefore, improving the heat resistance of oxide films has always been a difficult problem in the industry.

[0004] Table 1 Composition analysis of base detached materials

[0005] Summary of the Invention

[0006] 1. Problems to be solved

[0007] In response to the technical problem that the oxide film on the base of the PECVD equipment in the prior art has the oxide film pore size and the oxide film micropore density being too large or too small and uneven during the generation or regeneration process, resulting in the oxide film having poor heat resistance and easily falling off from the base, thus affecting the service life, the present application provides a method for preparing a heat-resistant base oxide film, which improves the oxide film structure, enhances the flexibility of the oxide film, and reduces the tensile stress between the oxide film and the base material during the continuous heating and cooling process. The prepared oxide film is not easy to crack under high-temperature impact, has significantly improved heat resistance, and significantly enhanced heat shock resistance, thereby meeting the performance requirements.

[0008] 2. Technical solution

[0009] In order to achieve the above objectives, the technical solutions provided are:

[0010] The present application provides a method for preparing a heat-resistant base oxide film, including an anodizing step, wherein the anodizing step comprises placing the base in an anodizing electrolyte for direct current anodizing: the electrolyte comprises the following components and contents: an organic acid is added to 2-8 wt% of an inorganic acid oxalic acid, and the organic acid is one or more of 0.5-3 wt% of glacial acetic acid, 1-3 wt% of citric acid, or 1-5 wt% of tartaric acid; the process temperature is 20-40°C; and the current density is 0.5-2 A / dm².

[0011] Furthermore, the electrolyte consists of the following components and contents: 5 wt % of oxalic acid and 1 wt % of glacial acetic acid.

[0012] Furthermore, the process temperature is 30°C.

[0013] Furthermore, the current density is 0.8A / dm 2 .

[0014] Furthermore, the brand of the substrate is Alcoa, Furukawa Sky Co., Ltd., Nannan Aluminum Co., Ltd. or Liaoning Zhongwang Group Co., Ltd.; the model of the substrate is 5052 or 6061.

[0015] Furthermore, the method further includes a step of regenerating the substrate before the anodizing step, wherein the regeneration step includes flatness correction, peeling, grinding and sandblasting.

[0016] Furthermore, the stripping steps include degreasing, pure water cleaning, etching, pure water cleaning, purification, pure water cleaning, and high-pressure water cleaning.

[0017] Preferably, degreasing (immersing in a sodium tripolyphosphate solution at 55°C for 5 minutes) → pure water washing → etching (immersing in a 3% sodium hydroxide solution at 40°C for 15 minutes to remove the oxide film) → pure water washing → purification (immersing in a 20% nitric acid solution at 30°C for 5 minutes to remove surface ash) → pure water washing → high-pressure water washing.

[0018] Furthermore, the grinding step is a two-step grinding: coarse grinding, grinding twice in the horizontal and vertical directions with 120# sandpaper; fine grinding: grinding once in the horizontal and vertical directions with 40# scouring pad.

[0019] Furthermore, the sandblasting step enables the surface roughness of the base to reach 18-22 μm.

[0020] Preferably, 20# glass beads are used, the blasting pressure is 2.5 kg, the spray gun distance is 400 mm, the moving speed is 300 mm / min, and the offset is 10 mm.

[0021] A heat-resistant base oxide film is prepared using the method described above; the oxide film has a thickness of 10-20 μm and can resist thermal shock 7 times at 450°C.

[0022] 3. Beneficial effects

[0023] Compared with the existing known technologies, the technical solution provided by the present invention has the following beneficial effects:

[0024] (1) The present invention provides a method for preparing a heat-resistant base oxide film, wherein the base is placed in an anodizing electrolyte and subjected to direct current anodizing. The electrolyte is 2-8 wt% of an inorganic acid oxalic acid, and one or more of 0.5-3 wt% of glacial acetic acid, 1-3 wt% of citric acid or 1-5 wt% of tartaric acid is added. The process temperature is 10-40°C, and the current density is 0.5-2 A / dm². In order to solve the problem that the base oxide film is cracked and detached due to insufficient heat resistance at a high temperature of 350-400°C and continuous thermal shock, the process parameters of the anodizing process are improved, such as the type of electrolyte, oxidation temperature and current density, thereby improving the oxide film structure, enhancing the flexibility of the oxide film, and reducing the tensile stress between the oxide film and the base material during continuous heating and cooling.

[0025] (2) The present invention provides a heat-resistant base oxide film, prepared using the aforementioned preparation method. The prepared oxide film solves the problem of cracking of the oxide film due to temperature fluctuations, significantly improves heat resistance, significantly enhances thermal shock resistance, and improves the performance of the base. The oxide film has a thickness of 10-20 μm and can withstand up to seven thermal shocks at 450°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the structure of CVD Chamber.

[0027] Figure 2 Schematic diagram of the microporous structure of the oxide film.

[0028] Figure 3 This is a photo of the oxide film peeling off under a magnifying glass.

[0029] Figure 4 This is a photo of the oxide film peeling off under a magnifying glass.

[0030] Figure 5 This is the EDS analysis spectrum of the peeled oxide film.

[0031] Figure 6 This is a schematic flow chart of a heat-resistant base oxide film and its preparation method in Example 1.

[0032] Figure 7 This is a photo of the oxide film prepared in Comparative Example 4.

[0033] Figure 8 This is a photo of a heat-resistant base oxide film prepared in Example 1.

[0034] Figure 9 This is a photo of the oxide film prepared in Comparative Example 5.

[0035] Figure 10 This is a photo of the oxide film prepared in Comparative Example 1.

[0036] Figure 11 This is a photo of the oxide film prepared in Comparative Example 2.

[0037] Figure 12 This is a photo of the oxide film prepared in Comparative Example 3.

[0038] Figure 13 This is a photo of the oxide film prepared in Comparative Example 6.

[0039] Figure 14 This is a photo of the oxide film prepared in Example 6.

[0040] Figure 15 This is a photo of the oxide film prepared in a parallel experiment of Example 1.

[0041] Figure 16 This is a photo of the oxide film prepared in Example 7.

[0042] Figure 17 This is a photo of the oxide film prepared in a parallel experiment of Example 1.

[0043] Figure 18 This is a photo of the oxide film prepared in Example 9.

[0044] Figure 19 This is a photo of the oxide film prepared in Example 10. DETAILED DESCRIPTION

[0045] In order to further understand the content of the present invention, the present invention is described in detail with reference to the embodiments and the accompanying drawings.

[0046] Example 1

[0047] The heat-resistant base oxide film and its preparation method in this embodiment uses a substrate brand of Alcoa, model 6061. Furukawa Sky Co., Ltd., Nannan Aluminum Co., Ltd. or Liaoning Zhongwang Group Co., Ltd., substrate models 5052 or 6061 are also applicable to this embodiment. See the process Figure 6 , including the following steps:

[0048] 1. Product warehousing: issue production orders; output process flow sheets.

[0049] 2. Inspection: Check the appearance and dimensions of the product; check the flatness. If there is no problem, proceed directly to the peeling step 5.

[0050] 3. Flatness correction: Reshaping by heat treatment or oil pressure; pay attention to product scratches.

[0051] 4. Inspection: Perform a flatness check.

[0052] 5. Stripping: Strip the original oxide film according to the process sheet.

[0053] Degreasing (immersion in sodium tripolyphosphate solution at 55°C for 5 minutes) → pure water washing → etching (immersion in 3% sodium hydroxide solution at 40°C for 15 minutes to remove oxide film) → pure water washing → purification (immersion in 20% nitric acid solution at 30°C for 5 minutes to remove surface ash) → pure water washing → high-pressure water washing.

[0054] 6. Grinding: Grind the entire surface through mechanical grinding to remove surface damage.

[0055] Coarse grinding: Grind twice with 120# sandpaper in both horizontal and vertical directions

[0056] Fine grinding: Grind with 40# scouring pad horizontally and vertically once

[0057] 7. Inspection: Check the surface condition to see if there are any scratches.

[0058] 8. Sand blasting: Sand blasting is performed according to customer needs.

[0059] Use 20# glass beads, sandblasting pressure 2.5Kg, spray gun distance 400mm, moving speed 300mm / min, offset 10mm, and sandblasting under these conditions to make the surface roughness reach 18~22μm.

[0060] 9. Inspection: Check the surface roughness and flatness.

[0061] 10. Anodizing: Confirm the surface condition before anodizing and perform anodizing according to the process requirements.

[0062] The substrate was placed in an anodizing electrolyte for direct current anodization: the electrolyte consisted of the following components and contents: 5wt% oxalic acid and 1wt% glacial acetic acid. The process temperature was 30°C. The current density was 0.8A / dm 2 .

[0063] 11. Inspection: Conduct final appearance and data inspection, and heating wire performance test.

[0064] 12. Packaging: Final drying and clean packaging.

[0065] In parallel experiments, the oxide films prepared were Figure 8 、 15 As shown in Figure 17, it has been tested that it can withstand thermal shock 7 times at 450°C.

[0066] Example 2

[0067] A heat-resistant base oxide film and a preparation method thereof of this embodiment are basically the same as those of Example 1, except that an organic acid is added to 2 wt % of the inorganic acid oxalic acid, and the organic acid is 0.5 wt % of glacial acetic acid; the process temperature is 20° C.; and the current density is 0.5 A / dm².

[0068] After testing, it can withstand thermal shock 3 times at 450℃.

[0069] Example 3

[0070] A heat-resistant base oxide film and a preparation method thereof of this embodiment are basically the same as those of Example 1, except that an organic acid is added to 8 wt % of the inorganic acid oxalic acid, and the organic acid is 3 wt % of glacial acetic acid; the process temperature is 40° C.; and the current density is 2 A / dm².

[0071] After testing, it can withstand thermal shock 3 times at 450℃.

[0072] Example 4

[0073] The heat-resistant base oxide film and preparation method thereof of this embodiment are basically the same as those of Example 1, except that an organic acid is added to 5 wt % of the inorganic acid oxalic acid, and the organic acid is 1.5 wt % of citric acid.

[0074] After testing, it can withstand thermal shock 5 times at 450℃.

[0075] Example 5

[0076] The heat-resistant base oxide film and preparation method thereof of this embodiment are basically the same as those of Example 1, except that an organic acid is added to 5 wt % of the inorganic acid oxalic acid, and the organic acid is 2.5 wt % of tartaric acid.

[0077] After testing, it can withstand thermal shock 5 times at 450℃.

[0078] Example 6

[0079] The heat-resistant base oxide film and preparation method thereof of this embodiment are basically the same as those of Example 1, except that the process temperature is 20°C.

[0080] The oxide film prepared is Figure 14 As shown, it has been tested that it can withstand thermal shock 5 times at 450°C.

[0081] Example 7

[0082] The heat-resistant base oxide film and preparation method thereof of this embodiment are basically the same as those of Example 1, except that the process temperature is 40°C.

[0083] The oxide film prepared is Figure 16 As shown, it has been tested that it can withstand thermal shock 5 times at 450°C.

[0084] Example 8

[0085] The heat-resistant base oxide film and its preparation method of this embodiment are basically the same as those of Example 1, except that the current density is 0.5A / dm 2 .

[0086] After testing, it can withstand thermal shock 3 times at 450℃.

[0087] Example 9

[0088] The heat-resistant base oxide film and its preparation method of this embodiment are basically the same as those of Example 1, except that the current density is 1A / dm 2 .

[0089] The oxide film prepared is Figure 18 As shown, the oxide film prepared is Figure 19 As shown, it has been tested that it can withstand thermal shock 3 times at 450°C.

[0090] Example 10

[0091] The heat-resistant base oxide film and its preparation method of this embodiment are basically the same as those of Example 1, except that the current density is 1.5A / dm 2 .

[0092] The oxide film prepared is Figure 19 As shown, it has been tested that it can withstand thermal shock 3 times at 450°C.

[0093] Comparative Example 1

[0094] The heat-resistant base oxide film and its preparation method in this comparative example are basically the same as those in Example 1, except that glacial acetic acid is not added. The oxide film prepared is as follows: Figure 10 shown.

[0095] After testing, it can withstand thermal shock once at 450℃.

[0096] Comparative Example 2

[0097] A heat-resistant base oxide film and a preparation method thereof in this comparative example are basically the same as those in Example 1, except that the amount of glacial acetic acid added is 0.4 wt %.

[0098] The oxide film prepared is Figure 11 As shown, it has been tested that it can withstand thermal shock 3 times at 450°C.

[0099] Comparative Example 3

[0100] A heat-resistant base oxide film and a preparation method thereof in this comparative example are basically the same as those in Example 1, except that the amount of glacial acetic acid added is 4 wt %.

[0101] The oxide film prepared is Figure 12 As shown, it has been tested that it can withstand thermal shock once at 450℃.

[0102] Comparative Example 4

[0103] The heat-resistant base oxide film and its preparation method in this comparative example are basically the same as those in Example 1, except that the electrolyte uses a mixed acid: sulfuric acid, oxalic acid and an organic acid; the mass concentration of the sulfuric acid is 8wt%, the mass concentration of the oxalic acid is 4wt%, and the mass concentration of the organic acid is tartaric acid, which is 2wt%. The oxide film prepared is as follows Figure 7 shown.

[0104] After testing, it can withstand thermal shock once at 450℃.

[0105] Comparative Example 5

[0106] The heat-resistant base oxide film and its preparation method in this comparative example are basically the same as those in Example 1, except that sulfuric acid is used as the electrolyte; the mass concentration of the sulfuric acid is 8wt%. The oxide film prepared is as follows Figure 9 shown.

[0107] After testing, it can withstand thermal shock once at 450℃.

[0108] Comparative Example 6

[0109] The heat-resistant base oxide film and preparation method thereof in this comparative example are basically the same as those in Example 1, except that the process temperature is 15°C.

[0110] The oxide film prepared is Figure 13 As shown, it has been tested that it can withstand thermal shock twice at 450°C.

[0111] It can be seen from Examples 1-5 and Comparative Examples 1-5 that the structural properties of the anodic oxide films prepared with different electrolytes are different, and the secondary dissolution ability is also different. Generally speaking, the pore size of the oxide film is in descending order of mixed acid, oxalic acid, and sulfuric acid, while the micropore density of the oxide film is in descending order of sulfuric acid, oxalic acid, and mixed acid. There are significant differences in their density and adhesion. Adding organic acids such as glacial acetic acid to the original oxalic acid electrolyte also significantly improves the heat resistance of the oxide film. The advantage of pure sulfuric acid is that the anode speed is faster, and the disadvantage is that sulfuric acid is relatively acidic, has stronger solubility for the oxide film, and the pore size of the oxide film will be slightly larger. When different concentrations of acetic acid are added to the oxalic acid solution, it can be found that the thermal cracking resistance of the obtained oxide film is better when 1wt% acetic acid is added when the thermal shock is at 450°C.

[0112] During the anodizing process, the aluminum alloy undergoes secondary dissolution due to its growing oxide film in an acidic solution, generating a large amount of Joule heat and generation heat. The temperature of the electrolyte will increase accordingly with time. At this time, the dissolution rate of the anodized film is accelerated, the dissolution effect is enhanced, the porosity of the oxide film increases, the film formation rate is correspondingly reduced, the corrosion resistance, wear resistance and hardness of the oxide film decrease, while the heat resistance increases. Therefore, the film properties obtained at different anode temperatures vary greatly. The bath temperature can be controlled by circulating refrigeration equipment to obtain an oxide film with corresponding properties. The anodizing temperature was increased from 15°C to 30°C, and the oxide film was subjected to continuous cyclic thermal shock testing in an environment of 450°C. It was found that at the oxidation temperature of 15°C, the oxide film cracked after the second thermal shock, while the oxide film at 30°C did not crack until the seventh shock.

[0113] The change of current density will affect the overall oxidation time and the density of the oxide film. The higher the current density, the shorter the oxidation time, the lower the dissolution of the oxide film in the acidic electrolyte, the denser the oxide film pores, the higher the hardness, but the corresponding heat resistance is insufficient. Therefore, the current density can be appropriately reduced to obtain a film with higher heat resistance. Under the same electrolyte conditions, anodizing with different current densities and then thermal shock at 450 ° C were carried out. It can be found that when the current density is low, the oxide film cracking is less.

Claims

1. A method for preparing a heat-resistant substrate oxide film, using a substrate, including an anodizing step, wherein the anodizing step comprises placing the substrate in an anodizing electrolyte and performing direct current anodizing, characterized in that: The electrolyte consists of the following components and contents: 5wt% oxalic acid and 1wt% glacial acetic acid; the process temperature is 30°C; the current density is 0.8A / dm²; the model of the substrate is 5052 or 6061; The oxide film can resist thermal shock 7 times at 450°C, and the base is a PECVD equipment base; The thickness of the oxide film is 10-20 μm.

2. The method for preparing a heat-resistant base oxide film according to claim 1, wherein: The brands of the substrate are Alcoa, Furukawa Sky Co., Ltd., Nannan Aluminum Co., Ltd. or Liaoning Zhongwang Group Co., Ltd.

3. The method for preparing a heat-resistant base oxide film according to claim 2, wherein: The method further comprises performing a substrate regeneration step before the anodizing step, wherein the regeneration step comprises flatness correction, peeling, grinding and sandblasting.

4. The method for preparing a heat-resistant base oxide film according to claim 3, wherein: The stripping step is degreasing, washing with pure water, Etching, pure water cleaning, purification, pure water washing, high pressure water washing cleaning.

5. The method for preparing a heat-resistant base oxide film according to claim 3, wherein: The grinding step is a two-step grinding: coarse grinding, grinding twice in the horizontal and vertical directions with 120# sandpaper; Fine grinding: Grind with 40# scouring pad horizontally and vertically once.

6. The method for preparing a heat-resistant base oxide film according to claim 3, wherein: The sandblasting step makes the surface roughness of the base reach 18-22 μm.

7. A heat-resistant base oxide film, characterized in that: It is prepared by the method according to any one of claims 1 to 6.

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