Titanium-aluminum composite member film removal treatment agent and titanium-aluminum composite member surface micro-pore treatment method

Abstract

The application belongs to the technical field of metal material surface treatment, and particularly relates to a titanium-aluminum composite part film stripping treatment agent and a titanium-aluminum composite part surface micropore treatment method. The titanium-aluminum composite part film stripping treatment agent comprises an accelerator, an inhibitor and a film stripping agent. The accelerator is nitrate or a nitro compound. The inhibitor is an inhibitor having an inhibiting effect on aluminum and an aluminum anode oxidation film under a strong acid. The film stripping agent is at least one selected from sulfuric acid and a sulfate. The titanium-aluminum composite part film stripping treatment agent provided by the application has very low damage on aluminum, can reduce the risk of aluminum corrosion to the maximum extent, reduce the risk of aluminum insulation oxidation film being broken down to compete for current, and can also strip the original oxidation film on the titanium base material, so that the oxidation film on the titanium is thinner during anode oxidation, which is beneficial to subsequent film stripping treatment or etching treatment.

Description

Technical Field

[0001] This invention belongs to the field of metal material surface treatment technology, specifically relating to a film removal agent for titanium-aluminum composite parts and a method for treating micropores on the surface of titanium-aluminum composite parts. Background Technology

[0002] In fields such as mobile communication devices, electronic and electrical equipment, and automotive machinery, the integrated metal and resin molding technology has been widely developed and applied to achieve goals such as reducing product weight and increasing bonding strength. Currently, many patents have emerged involving microporous injection molding technology for various materials. Metal structures have gradually shifted from single metals to composite parts, especially stainless steel and aluminum alloy composite parts integrated with resin molding technology, which has been widely used and promoted. Titanium alloys possess similar properties to stainless steel, and are also lighter, more biocompatible, and adaptable than stainless steel. Aluminum alloys offer good heat dissipation and are easy to CNC machine; therefore, titanium alloy and aluminum alloy composite parts are increasingly favored as the metal framework for wearable and smart devices.

[0003] Titanium-aluminum composite components offer significant processing advantages as the structural framework of smart products. However, to enhance signal transmission and reduce signal shielding, the device framework needs to be cut to prevent signal shielding. For example, the number of antenna slots in smartphones has increased from 4 to 8, 12, or even more. Therefore, developers have used microporous injection molding to connect the structural components. However, this presents new challenges for surface treatment. Titanium alloys and aluminum have very different chemical properties, and the methods for creating micropores on their surfaces are completely different.

[0004] Currently, the process for simultaneously microporousizing titanium-aluminum composite parts involves first anodizing the composite to form a protective oxide film of tens of micrometers on the aluminum surface, then etching the titanium, followed by deoxidation and etching the aluminum again. Typically, during anodizing, the oxide film on the aluminum continuously forms and thickens, while a thin oxide film also forms on the titanium. To ensure better subsequent titanium etching, this oxide film on the titanium usually needs to be removed.

[0005] Currently, methods for removing oxide films on titanium are divided into chemical and physical methods. Physical methods mainly involve CNC milling, grinding, or laser engraving. While physical methods can remove the oxide film on titanium without damaging the oxide film on aluminum, CNC machining is inefficient and costly, hindering continuous industrial production. Laser engraving is difficult to control; excessive power can ablate the substrate, forming a new, more difficult-to-remove oxide film on the titanium, while insufficient power cannot completely remove the oxide film. Its narrow application range, difficulty in control, and low yield all limit its use. Chemical removal methods are generally divided into acidic fluoride-containing stripping solutions and alkaline stripping solutions. While acidic fluoride-containing stripping solutions can quickly remove the oxide film on titanium and cause less damage to aluminum due to the fast stripping speed, making them suitable for microporous treatment of titanium-aluminum composite parts, their use is limited in many regions due to the fluoride content in the wastewater. Although alkaline stripping solutions are easy to treat for wastewater, they are slow to remove film, take a long time, and cause great damage to the oxide film on aluminum. In subsequent etching processes, the etching solution will corrode the aluminum substrate along the defects in the oxide film, making them unsuitable for titanium-aluminum composite parts. Summary of the Invention

[0006] One of the objectives of this invention is to address the shortcomings of existing technologies by providing a titanium-aluminum composite film removal agent that can quickly remove the titanium oxide film on titanium-aluminum composites with minimal damage to the aluminum. It can also remove the anodic oxide film on the titanium, ensuring that the aluminum material is not damaged during subsequent electrolytic etching of titanium on the titanium-aluminum composites. This facilitates subsequent surface treatment of the titanium-aluminum composites. Furthermore, this agent is fluorine-free and its wastewater treatment is simple.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a titanium-aluminum composite film removal agent, comprising an accelerator, a corrosion inhibitor, and a film removal agent; wherein the accelerator is nitrate or a nitro compound, the corrosion inhibitor is a corrosion inhibitor that has a corrosion inhibition effect on aluminum and aluminum anodic oxide film under strong acid, and the film removal agent is selected from at least one of sulfuric acid and sulfate.

[0008] In this invention, the stripping agent is at least one of sulfuric acid and sulfate. More specifically, the main component of the stripping agent is sulfuric acid, and sulfates can be appropriately introduced to reduce acidity, such as sodium sulfate, potassium sulfate, ammonium sulfate, etc. This invention does not impose specific limitations. It is worth mentioning that sulfates have little effect on chemical stripping, but sulfates can protect aluminum when electricity is applied for electrochemical stripping.

[0009] The existing method for removing the oxide film from titanium involves directly immersing the titanium-aluminum composite part in high-concentration sulfuric acid at a certain temperature for a period of time to remove the oxide film. This method has at least two drawbacks:

[0010] 1. Removing the oxide film from titanium takes a relatively long time;

[0011] Second, sulfuric acid itself also has a certain corrosive effect on aluminum oxide film.

[0012] The inventors discovered that a certain amount of nitrate or nitro compounds can promote the rapid removal of the oxide film on titanium by sulfuric acid, while causing minimal damage to the oxide film on aluminum in a relatively short time. This ensures that the titanium-aluminum composite parts achieve the goal of etching titanium with minimal aluminum loss in subsequent titanium etching solutions. Especially during the electrochemical removal of the titanium surface oxide film, although sulfuric acid can ensure that aluminum is basically not corroded when energized, a new oxide film will form on the titanium. However, a certain amount of nitrate or nitro compounds can inhibit the thickening of the oxide film on titanium. Even under long-term energization, only a very thin golden oxide film can be formed on the titanium, and it will not thicken during subsequent oxidation. In addition, the inventors also found that under energization, a large amount of gas is generated at the electrodes. Titanium alloy is a material that easily absorbs hydrogen. Under the flushing of a large amount of gas, the loose and porous oxide film on the titanium will absorb a large amount of gas, causing its volume to expand. During the gas overflow and flow, it is also easily washed away until it reaches its thinnest state.

[0013] Based on this, in order to shorten the deoxidation time and reduce the corrosion of the aluminum oxide film, the inventors proposed a solution: the titanium-aluminum composite deoxidation treatment agent includes an accelerator, a corrosion inhibitor, and a deoxidation agent, wherein nitrate or nitro compounds are used as the accelerator.

[0014] Furthermore, the accelerator is selected from one or more of nitric acid, sodium nitrate, potassium nitrate, ferric nitrate, copper nitrate, manganese nitrate, cerium nitrate, nickel nitrate, ammonium nitrate, guanidine nitrate, urea nitrate, nitrobenzenesulfonic acid and its salts, and nitrobenzene acid and its salts.

[0015] Furthermore, the corrosion inhibitor is selected from one or more of quinoline boric acid and its alcohol esters, thioamides, thiazole thiophenes, thiourea derivatives, imidazoles and their derivatives.

[0016] In this invention, the above-mentioned corrosion inhibitor can inhibit the corrosion of aluminum but has little effect on the corrosion of titanium. It can further reduce the corrosion of aluminum and oxide film by sulfuric acid solution, and ensure that the titanium-aluminum composite can achieve the purpose of etching titanium with minimal loss of aluminum in the subsequent titanium etching solution.

[0017] It should be noted that the titanium-aluminum composite in this invention is a composite formed by combining titanium alloy and aluminum alloy metal bases, rather than an alloy as understood in the metallurgical field, as both are heterogeneous phase metals. Specifically, it can be understood as a composite formed by bonding individual titanium alloy metals and individual aluminum alloy metals together after processing. The bonding methods include methods such as explosive welding, electromagnetic continuous casting, casting, hot melt pressing, diffusion welding, ultrasonic welding, casting composite method, rolling, and liquid-solid phase casting and rolling. Furthermore, composites formed by riveting, binding, pressing, etc., of titanium alloy and aluminum alloy also fall under the definition of composites described in this invention.

[0018] Those skilled in the art will know that titanium alloys and aluminum alloys have very different properties. Although both can form a natural oxide film in the air, the oxide film of aluminum is not resistant to corrosion, and is especially susceptible to chloride ion pitting corrosion when an electric current is applied.

[0019] To form a microporous layer with a depth and diameter of 20–200 μm on titanium, the best current method is electrochemical etching in a chlorine-containing solution. However, direct etching causes preferential corrosion of the aluminum alloy due to its poor corrosion resistance. The different potentials of the two dissimilar metals affect the overall electrochemical process of the composite, creating a galvanic cell or electrolytic cell effect. The aluminum alloy corrodes as the anode, while the titanium alloy becomes the cathode and is protected, limiting the formation of a microporous layer on the titanium alloy surface. To solve this problem, a thick layer of insulating alumina is first formed on the aluminum through electrochemical anodizing. With the insulating alumina protection, the aluminum alloy is well protected in the subsequent chlorine-containing titanium etching solution. This prevents severe corrosion of the aluminum material, which would reduce the product size, and also suppresses the electrochemical protective effect between the titanium and aluminum alloys, allowing more current to act on the titanium alloy surface and promoting the formation of the required microporous layer with a depth and diameter of 20–200 μm.

[0020] Based on known knowledge of aluminum alloy oxidation, we know that during anodizing, a barrier layer first forms on the aluminum alloy surface, followed by a porous layer. As the energizing time increases, the porous layer gradually thickens. Titanium alloys, on the other hand, are similar to the aluminum anodizing fixture, with an oxide film also forming on their surface. However, the oxide film on titanium alloys is dense, its thickness no longer increases significantly, and it is easily removed. To ensure the exposure of the active titanium alloy base layer before subsequent titanium etching, the oxide film on the titanium alloy needs to be removed, but it is also necessary to prevent corrosion of the aluminum oxide film as much as possible. Furthermore, if the titanium alloy surface has a certain thickness of natural oxide film, during subsequent oxidation, due to the influence of other elements in the titanium alloy, such as vanadium and aluminum, a film will continue to grow at the bottom of the original oxide film, relatively increasing the film thickness. Therefore, for titanium-aluminum composite parts with a thick original natural titanium oxide film, appropriate de-film removal treatment is required before anodizing. This is one of the purposes of the de-film removal agent for titanium-aluminum composite parts described in this invention.

[0021] The titanium-aluminum composite descaling agent provided by this invention can quickly remove the titanium oxide film on titanium-aluminum composites with minimal damage to aluminum. When using the chemical descaling method, it mainly relies on sulfuric acid to rapidly dissolve the titanium oxide film, combined with the synergistic effect of accelerator nitrate and aluminum corrosion inhibitor, which can dissolve the titanium oxide film in a very short time with minimal damage to aluminum.

[0022] The inventors considered that the main component of titanium oxide film is titanium dioxide, and fluoride ions have the best dissolving effect on it. Strong alkalis and complexing agents, oxalic acid, sulfuric acid, phosphoric acid, hydrochloric acid, etc., at medium to high temperatures and concentrations can also remove the oxide film on titanium. However, fluoride-containing stripping solutions are banned in many areas due to the fluoride content in wastewater. Although strong alkalis and complexing agents, oxalic acid, phosphoric acid, hydrochloric acid, etc., at certain temperatures and concentrations can also quickly remove the film, it has been verified that they cause greater damage to the oxide film on aluminum. The damaged oxide film is insufficient to support and protect the aluminum material from corrosion in subsequent titanium etching solutions. Based on this, the inventors discovered through experiments that sulfuric acid at a certain temperature and concentration, combined with a certain amount of nitrate or nitro compound accelerators and aluminum corrosion inhibitors, can achieve rapid removal of the oxide film on titanium while minimizing aluminum loss.

[0023] In this invention, the removal agent is used for either chemical or electrochemical removal. More specifically, for chemical removal of titanium oxide films, the sulfuric acid content can be appropriately high. Low sulfuric acid concentration results in slow removal speed and long removal time, which is detrimental to the protection of the aluminum oxide film. Excessively high sulfuric acid concentration leads to fast removal speed and less damage to the aluminum oxide film, but high-concentration sulfuric acid is too corrosive, posing operational hazards and hindering on-site control. Nitrate or nitro compound accelerators primarily function to promote the dissolution of the titanium oxide film during chemical removal, while their primary function during electrochemical removal is to inhibit the thickening of the titanium oxide film. Corrosion inhibitors mainly function to adsorb onto the aluminum surface, inhibiting the chemical corrosion of aluminum and the oxide film by acid.

[0024] The chemical immersion method involves a temperature of 40–90℃ and a time of 30–300 seconds. During chemical stripping, sulfuric acid, nitrate, nitro compounds, and corrosion inhibitors are typically used at their maximum concentrations. This high-temperature, short-time stripping method has the advantage of quickly and thoroughly removing the oxide film from titanium, but its disadvantage is that it causes more damage to aluminum than electrochemical stripping. After stripping, subsequent titanium etching directly forms a microporous layer on the titanium surface with a depth and diameter of 20–200 μm. Some of the pores in this microporous layer exhibit inverted triangle, overhang, or forked morphologies that facilitate adhesive adhesion.

[0025] In this invention, the electrochemical removal is performed at a temperature of 10–50°C for 6–60 minutes, with a voltage of 1–20V or a current density of 1–20A / dm². 2 When performing electrochemical stripping, sulfuric acid, nitrate or nitro compounds, and corrosion inhibitors are generally used at their lower concentration limits. The oxide film on titanium is removed under low temperature and electric current conditions. The advantages are low energy consumption and no damage to aluminum. The disadvantages are complex equipment requirements and the inability to completely remove the oxide film on titanium to zero, but rather to the thinnest state of the oxide film, which is basically yellow or golden yellow.

[0026] More specifically, when electricity is applied, a large amount of gas is generated at the two electrodes. Since titanium alloys are prone to hydrogen absorption, the loose, porous oxide film on the titanium absorbs a large amount of gas, causing it to expand in volume. As the gas overflows and flows, the oxide film on the titanium alloy is gradually washed away and electrolyzed until the thinnest titanium oxide film is exposed. During subsequent titanium etching, appropriately enhancing the etching conditions can also break through this thin film, thus forming a microporous layer on the titanium surface with a pore depth of 20–200 μm and a pore diameter of 20–200 μm. Some of the pores in this microporous layer have inverted triangle, inverted, or forked shapes that are beneficial for adhesive adhesion.

[0027] The titanium-aluminum composite descaling agent provided by this invention can remove both the original natural oxide film on titanium, inhibiting the thickening of the oxide film during subsequent anodizing, and the oxide film formed on titanium due to anodizing. In actual production, a layer of oxide film naturally forms on the titanium of the composite. Due to factors such as pre-processing, cutting, storage, and transportation, this natural oxide film can have a certain thickness. According to the inventors, if this oxide film is not removed, the oxide film on the titanium of the composite will thicken significantly during subsequent anodizing, resulting in a longer descaling time after oxidation or sealing, which is detrimental to the protection of the aluminum material during descaling. Therefore, for composites with a certain oxide film, descaling treatment is required before anodizing; for composites with a very thin oxide film or fresh substrates, this step can be ignored. During subsequent anodizing, an oxide film is formed on both titanium and aluminum surfaces. The oxide film on aluminum is mainly to protect aluminum during subsequent titanium etching. Therefore, it is necessary to minimize damage to it before etching. However, the oxide film on titanium will hinder the titanium etching process, causing defects such as uneven distribution of etched holes and poor hole morphology. Therefore, it is necessary to remove it as much as possible before etching. This is the second purpose of the titanium-aluminum composite part removal agent of this invention.

[0028] The second objective of this invention is to provide a method for treating micropores on the surface of titanium-aluminum composite parts, comprising the following steps:

[0029] S1. Place the titanium-aluminum composite part in sulfuric acid or mixed acid solution and pass an electric current to perform anodic oxidation, so that an oxide film of a certain thickness is generated on the surface of the titanium-aluminum composite part.

[0030] S2. The titanium-aluminum composite is subjected to a film removal treatment using the above-mentioned titanium-aluminum composite film removal agent to remove the oxide film on the titanium; and, before or after the film removal treatment, the titanium-aluminum composite is placed in an aluminum alloy sealing agent for sealing treatment.

[0031] S3. Place the titanium-aluminum composite part in a titanium etching solution for one or more anodic electrolytic etching treatments to create micropores on the titanium alloy.

[0032] S4. The titanium-aluminum composite is subjected to conventional treatment to complete the microporous treatment of the surface of the titanium-aluminum composite. The conventional treatment includes at least one of alkaline washing, descaling, rinsing and drying.

[0033] Furthermore, in step S3, the titanium etching solution includes halide ions, acid, positioning aid, and titanium corrosion inhibitor.

[0034] More specifically, the halide ions include one or more of fluoride ions, chloride ions, bromide ions, and iodide ions; the acid includes inorganic or organic acids, the inorganic acid includes one or more of phosphoric acid, sulfonic acid, hydrofluoric acid, boric acid, fluoroboric acid, fluorozirconic acid, fluorotitanic acid, and fluorosilicic acid, the organic acid includes one or more of citric acid, malic acid, tartaric acid, lactic acid, oxalic acid, propionic acid, gluconic acid, acetic acid and its derivatives, alkyl sulfonic acids and their derivatives, benzoic acid and its derivatives, and amino acids; the positioning aid includes positioning agents or fillers. The positioning agent includes one or more of sodium saccharin, sodium allyl sulfonate, sodium vinyl sulfonate, tetraacetyl ethylenediamine, dicyclohexylamine, formamide, dimethylformamide, tetrahydroxypropyl ethylenediamine, and diethylpropynylamine; the filler includes one or more of ethylene glycol and polyethylene glycol, propylene glycol and polypropylene glycol, glycerol and polyglycerol, sorbitol, mannitol, sugars, and polysaccharides; the titanium corrosion inhibitor includes one or more of iron ions, copper ions, sulfate ions, phosphate ions, nitrobenzoic acid, nitroaniline, alizarin, rutin, quinoline, and golden lotus orange.

[0035] Furthermore, step S3 also includes the following steps:

[0036] S31. Perform aluminum stripping and anodizing treatment on titanium-aluminum composite parts;

[0037] S32. Place the titanium-aluminum composite part in an aluminum chemical or electrochemical etching solution for one or more etching treatments to create micropores on the aluminum alloy.

[0038] Further, in step S3, the titanium-aluminum composite component is placed in a titanium etching solution for one or more anodic electrolytic etching treatments, under the following conditions: the titanium-aluminum composite component is placed in the titanium etching solution for anodic electrolytic etching for 5–30 min, wherein the anodic etching current is 1–10 A / dm. 2 The process is repeated 1 to 3 times at a temperature of 10 to 70°C to form a microporous layer with a depth of 20 to 200 μm and a diameter of 20 to 200 μm on the titanium surface of the titanium-aluminum composite.

[0039] In this invention, pretreatment includes, but is not limited to, degreasing, alkaline washing, and descaling.

[0040] It is worth mentioning that, in this invention, the titanium-aluminum composite film removal agent can be used to remove the film before aluminum alloy sealing of the titanium-aluminum composite, or after aluminum alloy sealing of the titanium-aluminum composite. The overall impact is not significant, and it is mainly related to the type of sealing agent and the sealing effect of the sealing agent itself.

[0041] In this invention, if the surface of the titanium-aluminum composite is clean and free of dirt and thick oxide film, it can be directly anodized. If the surface of the titanium-aluminum composite has dirt or a certain thickness of oxide film, it needs to be pretreated before anodizing, i.e. before step S1 in this invention. Specifically, the titanium-aluminum composite to be treated is pretreated to expose a clean and active substrate. The pretreatment includes, but is not limited to, degreasing, alkaline washing, dust removal, and removal of the natural oxide film on the titanium.

[0042] The inventors discovered that if the titanium-aluminum composite part has a thick oxide film on its surface, anodizing will cause the oxide film on the titanium to thicken further, resulting in a longer subsequent decoction time, which is not conducive to the protection of the aluminum material. In order to avoid the above situation, the present invention can perform decoction treatment before anodizing to remove or thin the original oxide film on the titanium substrate on the titanium-aluminum composite part, thereby reducing the thickness of the oxide film on the titanium during subsequent anodizing.

[0043] Specifically, before anodizing in step S1, the titanium-aluminum composite is placed in the above-mentioned titanium-aluminum composite stripping agent for stripping treatment.

[0044] In step S1 of this invention, anodizing can be performed using sulfuric acid or a mixture of acids, such as conventional sulfuric acid anodizing, or by adding appropriate additives to the sulfuric acid solution, such as aluminum salts, propylene glycol, glycerol, ethylene glycol, tartaric acid and its salts, boric acid and its salts, citric acid and its salts, lactic acid and its salts, oxalic acid and its salts, phosphoric acid and its salts, etc. One purpose is to improve the performance of the oxide film on aluminum, which is beneficial for protecting aluminum during subsequent titanium etching; another purpose is to make the oxide film on titanium thinner. When anodizing titanium-aluminum composite parts, a porous film is formed on the aluminum material and continuously thickens, and an oxide film of a certain thickness is also formed on the titanium. In particular, titanium alloys are more likely to form a slightly thicker oxide film than pure titanium. To reduce the difficulty of subsequent titanium oxide film removal, an appropriate complexing agent can be added to the anodizing bath to reduce the thickness of the oxide film on titanium.

[0045] More specifically, in a conventional sulfuric acid anodizing bath, a voltage of 14–20V is generally selected. Voltages within this range are the most suitable for aluminum oxide film formation, resulting in optimal aluminum oxide film performance. Within a certain timeframe, the thickness reaches a level sufficient to protect the aluminum from titanium etching. At this point, the titanium oxide film thickness is moderate, and its appearance is typically purplish-red to bluish-gray. To further reduce the removal time and thin the titanium oxide film, the oxidation parameters can be adjusted. Furthermore, the thickness and performance of the aluminum oxide film can be compensated for by adjusting the bath solution. For example, adding appropriate additives to the sulfuric acid solution, including but not limited to aluminum salts, propylene glycol, glycerol, ethylene glycol, tartaric acid and its salts, boric acid and its salts, citric acid and its salts, lactic acid and its salts, oxalic acid and its salts, and phosphoric acid and its salts, can increase the film formation rate of aluminum under the same charge, achieving the required aluminum film thickness while minimizing the titanium film thickness, resulting in a pale yellow to golden yellow appearance.

[0046] It is worth mentioning that, before anodizing, if the titanium-aluminum composite part undergoes a deoxide removal treatment, and the anodizing process is finely adjusted as described above, resulting in a thin, golden-yellow oxide film on the titanium, then no further deoxide removal treatment is needed before or after sealing. This allows for direct etching, creating a microporous layer on the titanium surface with a depth and diameter of 20–200 μm. Some of the pores in this microporous layer exhibit inverted triangle, overhang, or forked shapes, which are beneficial for adhesive adhesion. In other words, by combining deoxide removal before anodizing with adjustments during anodizing, the goals of deoxide removal, protection, and etching can be achieved.

[0047] In this invention, anodizing is not limited to anodizing with sulfuric acid or sulfuric acid with additives. It can also be anodizing with other acids as the main body, such as oxalic acid anodizing, chromic acid anodizing, phosphoric acid anodizing, etc., as well as hard anodizing, micro-arc anodizing, etc. The purpose of all these methods is to use the titanium alloy on the titanium-aluminum composite as a conductor and oxidize the aluminum alloy to form an oxide film that can withstand the titanium etching solution.

[0048] In this invention, after the anodizing treatment in step S1, the titanium-aluminum composite part is further subjected to a sealing treatment. The sealing treatment includes any one of water vapor evaporation sealing, nickel salt sealing, nickel-free sealing, and resin sealing. The purpose is to further enhance the corrosion resistance of the oxide film. However, for micro-arc oxidation and hard anodizing sealing steps with strong corrosion resistance, the sealing steps can be omitted.

[0049] After anodizing, the titanium-aluminum composite parts are further sealed. In this invention, in order to further reduce the difficulty of subsequent oxide film removal, additives such as complexing agents, halide ions, and hydrogen peroxide that have a weak effect on aluminum sealing can be appropriately added to the sealing agent. This can greatly reduce the oxide film on titanium while having a small impact on the aluminum sealing performance.

[0050] Conventional titanium oxide film removal agents, such as those using alkali with complexing agents, oxalic acid with heating, and hydrochloric acid with heating, can severely damage the aluminum oxide film, greatly reducing the breakdown voltage of the insulating oxide film on the aluminum, and may even remove the insulating oxide film on the aluminum, causing the aluminum to be corroded during subsequent titanium etching and resulting in poor pore formation on the titanium.

[0051] The inventors also discovered that placing titanium-aluminum composite parts in a titanium etching solution for one or more anodic electrolytic etching treatments creates micropores on the titanium alloy. After electrolytic etching with the aforementioned etching solution, a microporous layer with a depth of 20–200 μm and a diameter of 20–200 μm can be formed on the surface of the titanium alloy. During the etching process, halide ions pit corrode the titanium under the action of current. At this time, due to the protection of the insulating oxide film on the aluminum, the current is basically not divided, and most of the applied current acts on the titanium. However, as the reaction proceeds, the insulating oxide film on the aluminum may be broken down at any time, causing corrosion of the aluminum. Since the pitting corrosion resistance of aluminum is significantly weaker than that of titanium, a large amount of current will be transferred from titanium to aluminum. The current on titanium weakens, the pitting effect on titanium deteriorates, and the corrosion of aluminum intensifies. The current further transfers to aluminum, the current on titanium weakens further, and the pitting effect deteriorates further, forming a vicious cycle that leads to the corrosion of aluminum, and the pitting effect on titanium does not meet the requirements.

[0052] Based on this, the titanium-aluminum composite stripping agent provided by the present invention can not only remove the original oxide film on the titanium substrate, making the oxide film on the titanium thinner during anodizing, which is beneficial for subsequent stripping or etching processes, but also quickly remove the oxide film on the titanium, exposing the active titanium substrate and enabling rapid pore formation on the titanium.

[0053] Furthermore, the titanium-aluminum composite film stripping agent described in this invention causes very little damage to aluminum, which can minimize the risk of aluminum corrosion and reduce the risk of the aluminum insulating oxide film being broken down and competing for current.

[0054] The beneficial effects of this invention are as follows:

[0055] 1. The stripping agent described in this invention is more environmentally friendly than traditional fluorine-containing stripping solutions, and the wastewater treatment is simple. Compared with alkaline stripping solutions, it causes very little damage to aluminum materials and can effectively protect aluminum and oxide film while removing titanium oxide film.

[0056] 2. The titanium-aluminum composite stripping agent provided by this invention can not only remove the original oxide film on the titanium substrate, making the oxide film on the titanium thinner during anodizing, which is beneficial for subsequent stripping or etching processes, but also quickly remove the oxide film on the titanium, exposing the active titanium substrate and enabling rapid pore formation on the titanium.

[0057] 3. Compared with conventional titanium oxide film removal agents such as alkali plus complexing agent, or oxalic acid heating, hydrochloric acid heating, etc., the titanium-aluminum composite film removal agent provided by the present invention has very low damage to aluminum, which can minimize the risk of aluminum corrosion and reduce the risk of aluminum insulating oxide film breakdown competing for current. Attached Figure Description

[0058] The features, advantages, and technical effects of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings.

[0059] Figure 1 This is a flowchart of the method for treating micropores on the surface of titanium-aluminum composite parts in this invention. Detailed Implementation

[0060] The present invention will be further described in detail below with reference to embodiments, but this is not intended to limit the present invention.

[0061] Example 1

[0062] This embodiment 1 provides a method for microporous treatment of the surface of a titanium-aluminum composite component, including the following steps:

[0063] (1) Take the titanium-aluminum composite parts to be processed and pre-treat them so that the clean and active substrate is exposed. The pre-treatment includes, but is not limited to, degreasing, alkaline washing, and dust removal.

[0064] Specifically, the titanium-aluminum composite product (with titanium and aluminum each occupying 1 / 2 of the surface area) is first placed in a special cleaning agent for titanium-aluminum composite products, CW-6007 (manufacturer: Dongguan Huizeling Chemical Technology Co., Ltd.), and cleaned for 5-10 minutes, followed by thorough rinsing with water. The cleaning temperature is 40-60℃, and ultrasonic cleaning can be used to assist in the cleaning effect. In addition, to further activate the surface of the titanium-aluminum composite product, after degreasing and cleaning, the titanium-aluminum composite product can be immersed in a sodium hydroxide alkaline etching tank of 40-60g / L for 1-3 minutes to remove the oxide film on the aluminum surface, and then rinsed with water at a temperature of 40-60℃. Then, it is immersed in a nitric acid desiccant tank of 100-300ml / L for 2-5 minutes to remove the black ash produced by alkali etching on the aluminum surface, and then rinsed with water at room temperature. Alternatively, a commercially available special desiccant can be used instead of nitric acid for desiccant removal.

[0065] (2) The pretreated titanium-aluminum composite parts are placed in a titanium-aluminum composite stripping agent for chemical stripping treatment to remove the original oxide film on the titanium part.

[0066] Specifically, the titanium-aluminum composite parts treated in step (1) are immersed in 400-500 g / L sulfuric acid, 10-30 g / L nitric acid, and 5-10 g / L amidothiourea for 30-60 seconds, and then washed with water at a temperature of 80°C.

[0067] (3) Place the titanium-aluminum composite parts that have undergone the film removal treatment in sulfuric acid or mixed acid solution and anoly oxidize them by passing an electric current through the solution to generate an oxide film of a certain thickness on the surface of the composite parts.

[0068] Specifically, the titanium-aluminum composite parts treated in step (2) are placed in a solution of 150-250 g / L sulfuric acid and 10-10 g / L tartaric acid, electrolyzed at 18-20°C for 40-60 min, and then washed with water.

[0069] (4) The anodized titanium-aluminum composite parts are placed in an aluminum alloy sealing agent for sealing treatment.

[0070] Specifically, the titanium-aluminum composite parts treated in step (3) are placed in aluminum alloy special sealing agent CWF~7120 (manufacturer: Dongguan Huizeling Chemical Technology Co., Ltd.) for sealing. The sealing time is calculated as 3~4min / um, and the temperature is set to 93~98℃. After sealing, the parts are washed with water.

[0071] (5) Place the sealed titanium-aluminum composite parts in a titanium-aluminum composite parts stripping agent for chemical stripping treatment to remove the oxide film on the titanium parts.

[0072] Specifically, the titanium-aluminum composite parts treated in step (4) are immersed in 400-500 g / L sulfuric acid, 10-30 g / L nitric acid, and 5-10 g / L amidothiourea for 30-60 seconds, and then washed with water at a temperature of 80°C.

[0073] (6) Place the sealed titanium-aluminum composite in a titanium etching solution for one or more anodic electrolytic etching processes to create micropores on the titanium alloy.

[0074] Specifically, the titanium-aluminum composite part after oxidation sealing in step (5) is placed in a titanium micro-etching solution and anodic electrolytic etching is performed at 60°C for 10 minutes, with the anodic current set to 3A / dm. 2 The titanium micro-etching solution is a combination of 10-30 g / L ferric chloride, 100-300 g / L propylene glycol, 300-400 g / L polyglycerol, 5-10 g / L tartaric acid, 5-10 g / L p-nitrobenzoic acid, and 5-10 g / L sodium allyl sulfonate. To further increase the pore density, the electrochemically micro-etched titanium-aluminum alloy can be cleaned and the above electrolytic etching can be repeated once. The electrolytic etching parameters can remain unchanged or be adjusted appropriately.

[0075] When the surface-treated titanium-aluminum composite parts are observed using an optical microscope, micropores with a diameter of 20-200 μm and a depth of 20-200 μm are uniformly distributed on the titanium surface, and there is basically no corrosion on the aluminum.

[0076] (7) The titanium-aluminum composite parts that have undergone titanium etching are subjected to aluminum removal and anodic oxide film removal treatment. The specific deoxidation film removal is alkaline deoxidation such as sodium hydroxide, potassium hydroxide, etc., or acidic deoxidation film removal such as phosphoric acid, oxalic acid, etc. There are no restrictions here. Those skilled in the art can also select suitable reagents to remove the anodic oxide film on the aluminum based on common knowledge.

[0077] Specifically, the titanium-aluminum composite parts after the titanium etching treatment in step (6) are immersed in a 20-50 g / L sodium hydroxide solution for 30-100 seconds and then washed with water at a temperature of 40-50°C.

[0078] (8) The deoxidized titanium-aluminum composite is placed in an aluminum chemical or electrochemical etching solution for one or more etching treatments to create micropores on the aluminum alloy. Aluminum chemical etching or electrochemical etching can be a known aluminum etching surface treatment method, and there is no restriction here.

[0079] Specifically, the titanium-aluminum composite parts treated with the aluminum oxide film in step (7) are immersed in the solution for 30-60 seconds at a temperature of 50°C. After removing the oxide film, they are washed clean with water. Then, the titanium-aluminum alloy is immersed in an aqueous solution of 10-10 g / L ferric chloride, 10-20 g / L tartaric acid, 1-2 g / L benzoic acid, and 1-2 g / L thiourea for 1-2 minutes, washed with water, and cleaned. This process is repeated 2-3 times.

[0080] (9) Perform routine alkaline washing, ash removal, rinsing and drying on the titanium-aluminum composite gold after aluminum etching to complete the microporous treatment on the surface of the titanium-aluminum composite.

[0081] The surface-treated test piece was observed using an optical microscope. It was found that the titanium-aluminum surface was uniformly distributed with micropores with a diameter of 20-200 μm and a depth of 20-200 μm, which is the desired pore morphology.

[0082] Example 2

[0083] Unlike Example 1, Example 2 uses an electrochemical stripping process for removing the oxide film on titanium in step (2).

[0084] Specifically, the titanium-aluminum composite parts requiring film removal are placed in a titanium film removal solution and removed under a 10V voltage for 8 minutes at room temperature. The titanium film removal solution consists of 100-200 g / L sulfuric acid, 10-30 g / L nitric acid, and 5-10 g / L amidothiourea.

[0085] Other processing methods are exactly the same as in Example 1, and will not be repeated here.

[0086] After the titanium etching process in step (6) is completed, the surface-treated titanium-aluminum composite part is observed under an optical microscope. It can be seen that the titanium surface is uniformly distributed with micropores with a diameter of 20-200 μm and a depth of 20-200 μm, and there is basically no corrosion on the aluminum.

[0087] Example 3

[0088] Unlike Example 1, in this Example 3, the oxide film on the titanium is removed in step (5) by an electrochemical removal process.

[0089] Specifically, the titanium-aluminum composite parts requiring film removal are placed in a titanium film removal solution and removed under a 10V voltage for 8 minutes at room temperature. The titanium film removal solution consists of 100-200 g / L sulfuric acid, 10-30 g / L nitric acid, and 5-10 g / L amidothiourea.

[0090] Other processing methods are exactly the same as in Example 1, and will not be repeated here.

[0091] After the titanium etching process in step (6) is completed, the surface-treated titanium-aluminum composite part is observed under an optical microscope. It can be seen that the titanium surface is uniformly distributed with micropores with a diameter of 20-200 μm and a depth of 20-200 μm, and it has basically no corrosion to aluminum.

[0092] Example 4

[0093] Unlike Example 1, Example 4 uses electrochemical stripping treatment for removing the oxide film on titanium in steps (2) and (5) and adjusts the titanium stripping solution formula.

[0094] Specifically, the titanium-aluminum composite parts requiring decoction are placed in a titanium decoction solution and decoction is performed at 10V for 8 minutes at room temperature. The titanium decoction solution consists of 100-200g / L sulfuric acid, 10-30g / L nitric acid, and 5-10g / L amidothiourea.

[0095] Other processing methods are exactly the same as in Example 1, and will not be repeated here.

[0096] After the titanium etching process in step (6) is completed, the surface-treated titanium-aluminum composite part is observed under an optical microscope. It can be seen that the titanium surface is uniformly distributed with micropores with a diameter of 20-200 μm and a depth of 20-200 μm, and it has basically no corrosion to aluminum.

[0097] Example 5

[0098] Unlike Example 1, in Example 5, the titanium stripping solution in steps (2) and (5) is adjusted to 400-500 g / L sulfuric acid, 10-30 g / L sodium m-nitrobenzoate, and 5-10 g / L pinacol quinoline borate.

[0099] Other processing methods are exactly the same as in Example 1, and will not be repeated here.

[0100] After the titanium etching process in step (6) is completed, the surface-treated titanium-aluminum composite part is observed under an optical microscope. It can be seen that the titanium surface is uniformly distributed with micropores with a diameter of 20-200 μm and a depth of 20-200 μm, and the aluminum is basically uncorroded.

[0101] Example 6

[0102] Unlike Example 5, Example 6 employs electrochemical stripping treatment in steps (2) and (5) for removing the oxide film from titanium, and the titanium stripping solution formulation has been adjusted. Specifically, the titanium-aluminum composite component requiring stripping is placed in the titanium stripping solution at 5A / dm³. 2 The titanium film was stripped under current for 8 minutes at room temperature. The titanium stripping solution consisted of 100-200 g / L sulfuric acid, 10-30 g / L sodium m-nitrobenzoate, and 5-10 g / L pinacol quinoline borate.

[0103] Other processing methods are exactly the same as in Example 5, and will not be repeated here.

[0104] After the titanium etching process in step (6) is completed, the surface-treated titanium-aluminum composite part is observed under an optical microscope. It can be seen that the titanium surface is uniformly distributed with micropores with a diameter of 20-200 μm and a depth of 20-200 μm, and it has basically no corrosion to aluminum.

[0105] Example 7

[0106] Unlike Example 1, in Example 7, the titanium-aluminum composite parts are all fresh workpieces. The titanium oxide film on the composite parts is a very thin natural oxide film. The film removal process in steps (1) and (2) is not performed. Steps (3) to (5) are performed directly. Steps (3) to (5) are the same as in Example 1.

[0107] The processing method is exactly the same as in Example 1, and will not be repeated here.

[0108] After the titanium etching process in step (6) is completed, the surface-treated titanium-aluminum composite part is observed under an optical microscope. It can be seen that the titanium surface is uniformly distributed with micropores with a diameter of 20-200 μm and a depth of 20-200 μm, and it has basically no corrosion to aluminum.

[0109] Example 8

[0110] Unlike Example 1, in Example 8, the titanium-aluminum composite is first subjected to chemical stripping treatment, and then the titanium-aluminum composite is subjected to sealing treatment.

[0111] Specifically as follows:

[0112] (4) Place the anodized titanium-aluminum composite parts in a titanium-aluminum composite parts stripping agent for chemical stripping treatment to remove the oxide film on the titanium parts;

[0113] Specifically, the titanium-aluminum composite parts treated in step (3) are immersed in 400-500 g / L sulfuric acid, 10-30 g / L sodium nitrate, and 5-10 g / L mercaptobenzothiazole for 30-60 seconds, and then rinsed with water at a temperature of 80°C.

[0114] (5) Place the titanium-aluminum composite parts that have undergone the film removal treatment in an aluminum alloy sealing agent for sealing treatment;

[0115] Specifically, the titanium-aluminum composite parts treated in step (4) are placed in aluminum alloy special sealing agent CWF~7120 (manufacturer: Dongguan Huizeling Chemical Technology Co., Ltd.) for sealing. The sealing time is calculated as 3~4min / um, and the temperature is set to 93~98℃. After sealing, the parts are washed with water.

[0116] Other processing methods are exactly the same as in Example 1, and will not be repeated here.

[0117] Example 9

[0118] Unlike Example 8, Example 9 uses an electrochemical stripping process for the oxide film on the titanium in step (2).

[0119] Specifically, the titanium-aluminum composite parts requiring film removal are placed in a titanium film removal solution and removed under a 10V voltage for 8 minutes at room temperature. The titanium film removal solution consists of 100-200 g / L sulfuric acid, 10-30 g / L sodium nitrate, and 5-10 g / L mercaptophenylprophiazole.

[0120] Other processing methods are exactly the same as in Example 8, and will not be repeated here.

[0121] After the titanium etching process in step (6) is completed, the surface-treated titanium-aluminum composite part is observed under an optical microscope. It can be seen that the titanium surface is uniformly distributed with micropores with a diameter of 20-200 μm and a depth of 20-200 μm, and the aluminum is basically uncorroded.

[0122] Example 10

[0123] Unlike Example 8, Example 10 uses an electrochemical stripping process for removing the oxide film on titanium in step (4).

[0124] Specifically, the titanium-aluminum composite parts requiring film removal are placed in a titanium film removal solution and removed under a 10V voltage for 8 minutes at room temperature. The titanium film removal solution consists of 100-200 g / L sulfuric acid, 10-30 g / L sodium nitrate, and 5-10 g / L mercaptophenylprophiazole.

[0125] Other processing methods are exactly the same as in Example 8, and will not be repeated here.

[0126] After the titanium etching process in step (6) is completed, the surface-treated titanium-aluminum composite part is observed under an optical microscope. It can be seen that the titanium surface is uniformly distributed with micropores with a diameter of 20-200 μm and a depth of 20-200 μm, and it has basically no corrosion to aluminum.

[0127] Example 11

[0128] Unlike Example 8, Example 11 uses electrochemical stripping treatment for removing the oxide film on titanium in steps (2) and (4) and adjusts the titanium stripping solution formula.

[0129] Specifically, the titanium-aluminum composite parts requiring film removal are placed in a titanium film removal solution and removed under a 10V voltage for 8 minutes at room temperature. The titanium film removal solution consists of 100-200 g / L sulfuric acid, 10-30 g / L sodium nitrate, and 5-10 g / L mercaptophenylprophiazole.

[0130] Other processing methods are exactly the same as in Example 8, and will not be repeated here.

[0131] After the titanium etching process in step (6) is completed, the surface-treated titanium-aluminum composite part is observed under an optical microscope. It can be seen that the titanium surface is uniformly distributed with micropores with a diameter of 20-200 μm and a depth of 20-200 μm, and the aluminum is basically uncorroded.

[0132] Example 12

[0133] Unlike Example 8, in Example 12, the titanium stripping solution in steps (2) and (4) is adjusted to 400-500 g / L sulfuric acid, 10-30 g / L guanidine nitrate, and 5-10 g / L caprolactam.

[0134] Other processing methods are exactly the same as in Example 8, and will not be repeated here.

[0135] After the titanium etching process in step (6) is completed, the surface-treated titanium-aluminum composite part is observed under an optical microscope. It can be seen that the titanium surface is uniformly distributed with micropores with a diameter of 20-200 μm and a depth of 20-200 μm, and there is basically no corrosion on the aluminum.

[0136] Example 13

[0137] Unlike Example 12, Example 13 uses electrochemical stripping treatment for removing the oxide film on titanium in steps (2) and (4) and adjusts the titanium stripping solution formula.

[0138] Specifically, the titanium-aluminum composite parts requiring film removal are placed in a titanium film removal solution at 5A / dm.2 The titanium film was stripped under current for 8 minutes at room temperature. The titanium stripping solution consisted of 100-200 g / L sulfuric acid, 10-30 g / L guanidine nitrate, and 5-10 g / L caprolactam.

[0139] Other processing methods are exactly the same as in Example 12, and will not be repeated here.

[0140] After the titanium etching process in step (6) is completed, the surface-treated titanium-aluminum composite part is observed under an optical microscope. It can be seen that the titanium surface is uniformly distributed with micropores with a diameter of 20-200 μm and a depth of 20-200 μm, and there is basically no corrosion on the aluminum.

[0141] Example 14

[0142] Unlike Example 8, the titanium-aluminum composite parts in Example 14 are all fresh workpieces. The titanium oxide film on the composite parts is a very thin natural oxide film, and the processing steps (3) to (5) are carried out directly.

[0143] The processing method is exactly the same as in Example 8, and will not be repeated here.

[0144] After the titanium etching process in step (6) is completed, the surface-treated titanium-aluminum composite part is observed under an optical microscope. It can be seen that the titanium surface is uniformly distributed with micropores with a diameter of 20-200 μm and a depth of 20-200 μm, and there is basically no corrosion on the aluminum.

[0145] Example 15

[0146] Unlike the previous embodiment, this embodiment 15 provides a method for microporous treatment of the surface of a titanium-aluminum composite component. By adjusting the combination of oxide film removal before anodizing and anodizing, micropores can be directly etched without the need for oxide film removal before and after sealing. The specific steps are as follows:

[0147] (1) Take the titanium-aluminum composite parts to be processed and perform pretreatment to expose a clean and active substrate. The pretreatment includes, but is not limited to, degreasing, alkaline washing, and descaling.

[0148] Specifically, the titanium-aluminum composite product (with titanium and aluminum each occupying 1 / 2 of the surface area) is first placed in a special cleaning agent for titanium-aluminum composite products, CW-6007 (manufacturer: Dongguan Huizeling Chemical Technology Co., Ltd.), and cleaned for 5-10 minutes, followed by thorough rinsing with water. The cleaning temperature is 40-60℃, and ultrasonic cleaning is even more effective. In addition, to further activate the surface of the titanium-aluminum composite product, the degreased composite product can be immersed in a 40-60g / L sodium hydroxide alkaline etching bath for 1-3 minutes to remove the oxide film on the aluminum surface, followed by rinsing with water at a temperature of 40-60℃. Then, it is immersed in a 100-300ml / L nitric acid desiccant bath for 2-5 minutes to remove the black ash produced by alkali etching on the aluminum surface, followed by rinsing with water at room temperature. Alternatively, a commercially available special desiccant can be used instead of nitric acid for desiccant removal.

[0149] (2) The pretreated titanium-aluminum composite parts are placed in a titanium-aluminum composite stripping agent for chemical stripping treatment to remove the original oxide film on the titanium part.

[0150] Specifically, the titanium-aluminum composite parts treated in step (1) are immersed in 400-500 g / L sulfuric acid, 10-30 g / L sodium nitrate, and 5-10 g / L mercaptobenzothiazole for 100-600 seconds, and then washed with water at a temperature of 80°C.

[0151] (3) Place the titanium-aluminum composite parts that have undergone the film removal treatment in sulfuric acid or mixed acid solution and anoly oxidize them by passing an electric current through the solution to generate an oxide film of a certain thickness on the surface of the composite parts.

[0152] Specifically, the titanium-aluminum composite parts treated in step (2) are placed in a solution of 150-250 g / L sulfuric acid, 10-20 g / L tartaric acid, and 300-400 g / L propylene glycol. After electrolysis at 18-20°C for 40-60 min, they are washed with water. At this time, the titanium oxide film on the titanium-aluminum composite parts appears yellow or golden yellow.

[0153] (4) The titanium-aluminum composite parts that have undergone anodizing are placed in an aluminum alloy sealing agent for sealing treatment;

[0154] Specifically, the titanium-aluminum composite parts treated in step (4) are placed in aluminum alloy special sealing agent CWF~7120 (produced by Dongguan Huizeling Chemical Technology Co., Ltd.) for sealing. The sealing time is calculated as 3~4 min / um, and the temperature is set to 93~98℃. After sealing, the parts are washed with water.

[0155] (5) Place the sealed titanium-aluminum composite parts in a titanium etching solution for one or more anodic electrolytic etching processes to create micropores on the titanium alloy.

[0156] Specifically, the titanium-aluminum composite part after oxidation sealing in step (5) is placed in a titanium micro-etching solution and anodic electrolytic etching is performed at 60°C for 10 minutes, with the anodic current set to 3A / dm. 2 The titanium micro-etching solution is a combination of 10-30 g / L ferric chloride, 100-300 g / L propylene glycol, 300-400 g / L polyglycerol, 5-10 g / L tartaric acid, 5-10 g / L p-nitrobenzoic acid, and 5-10 g / L sodium allyl sulfonate. To further increase the pore density, the electrochemically micro-etched titanium-aluminum alloy can be cleaned and the above electrolytic etching can be repeated once. The electrolytic etching parameters can remain unchanged or be adjusted appropriately.

[0157] When the surface-treated titanium-aluminum composite parts are observed using an optical microscope, micropores with a diameter of 20-200 μm and a depth of 20-200 μm are uniformly distributed on the titanium surface, and there is basically no corrosion on the aluminum.

[0158] (6) The titanium-aluminum composite parts that have undergone titanium etching are subjected to aluminum stripping and anodizing film treatment. The anodizing film is specifically alkaline deoxidation such as sodium hydroxide, potassium hydroxide, etc., or acidic deoxidation such as phosphoric acid, oxalic acid, etc. There are no restrictions here.

[0159] Specifically, the titanium-aluminum composite parts after the titanium etching treatment in step (5) are immersed in a 20-50 g / L sodium hydroxide solution for 30-100 seconds and then washed with water at a temperature of 40-50℃.

[0160] (7) The deoxidized titanium-aluminum composite is placed in an aluminum chemical or electrochemical etching solution for one or more etching treatments to create micropores on the aluminum alloy. Aluminum chemical etching or electrochemical etching can be a known aluminum etching surface treatment method, and there is no restriction here.

[0161] Specifically, the titanium-aluminum composite parts treated with the aluminum oxide film in step (6) are immersed in the solution for 30-60 seconds at a temperature of 50°C. After removing the oxide film, they are washed clean with water. Then, the titanium-aluminum alloy is immersed in an aqueous solution of 10-10 g / L ferric chloride, 10-10 g / L tartaric acid, 1-2 g / L benzoic acid, and 1-2 g / L thiourea for 1-2 minutes, washed with water, and cleaned. This process is repeated 2-3 times.

[0162] (8) Perform routine alkaline washing, ash removal, rinsing and drying on the titanium-aluminum composite gold after aluminum etching to complete the microporous treatment on the surface of the titanium-aluminum composite.

[0163] The surface-treated test piece was observed using an optical microscope. It was found that the titanium-aluminum surface was uniformly distributed with micropores with a diameter of 20-200 μm and a depth of 20-200 μm, which is the desired pore morphology.

[0164] Example 16

[0165] The difference from Example 15 is that in this Example 16, the titanium stripping solution in step (2) is adjusted to 400-500 g / L of sulfuric acid, 10-30 g / L of guanidine nitrate, and 5-10 g / L of caprolactam.

[0166] Other processing methods are exactly the same as in Example 16, and will not be repeated here.

[0167] After the titanium etching process in step (5) is completed, the surface-treated titanium-aluminum composite part is observed under an optical microscope. It can be seen that the titanium surface is uniformly distributed with micropores with a diameter of 20-200 μm and a depth of 20-200 μm, and there is basically no corrosion on the aluminum.

[0168] Example 17

[0169] Unlike Example 15, in Example 17, the titanium stripping solution in step (2) is adjusted to 400-500 g / L sulfuric acid, 10-30 g / L guanidine nitrate, and 5-10 g / L caprolactam. In step (3), the anodizing bath solution is adjusted to 150-250 g / L sulfuric acid, 10-20 g / L boric acid, 10-20 g / L oxalic acid, and 300-400 g / L ethylene glycol solution. Electrolysis is performed at 18-20°C for 40-60 minutes, followed by rinsing with water. At this point, the titanium oxide film on the titanium-aluminum composite part appears yellow or golden yellow.

[0170] Other processing methods are exactly the same as in Example 15, and will not be repeated here.

[0171] After the titanium etching process in step (5) is completed, the surface-treated titanium-aluminum composite part is observed under an optical microscope. It can be seen that the titanium surface is uniformly distributed with micropores with a diameter of 20-200 μm and a depth of 20-200 μm, and there is basically no corrosion on the aluminum.

[0172] Example 18

[0173] Unlike Example 15, Example 18 uses an electrochemical removal process for the oxide film on the titanium in step (2) and adjusts the titanium removal solution formula.

[0174] Specifically, the titanium-aluminum composite parts requiring film removal are placed in a titanium film removal solution at 5A / dm. 2 The titanium film was stripped under current for 8 minutes at room temperature. The titanium stripping solution consisted of 100-200 g / L sulfuric acid, 10-30 g / L p-nitrobenzoic acid, and 5-10 g / L methylphenidate.

[0175] Other processing methods are exactly the same as in Example 15, and will not be repeated here.

[0176] After the titanium etching process in step (5) is completed, the surface-treated titanium-aluminum composite part is observed under an optical microscope. It can be seen that the titanium surface is uniformly distributed with micropores with a diameter of 20-200 μm and a depth of 20-200 μm, and there is basically no corrosion on the aluminum.

[0177] Comparative Example 1

[0178] Unlike Example 1, this example omits steps (2) and (5), meaning that the composite is directly oxidized and sealed after pretreatment, and then directly etched after sealing.

[0179] Other processing methods are exactly the same as in Example 1, and will not be repeated here.

[0180] After the titanium etching process in step (5), the surface-treated titanium-aluminum composite was observed under an optical microscope. It was found that the uniformly distributed pores on the titanium surface were highly uneven, appearing as scattered, large, bowl-shaped pores, while the aluminum showed virtually no corrosion. This indicates that while direct etching of the titanium-aluminum composite after oxidation can protect the aluminum from corrosion, without titanium stripping, the thick oxide film on the titanium hinders the pitting corrosion of titanium by chloride ions under current, resulting in poor pore formation on the titanium and failing to meet requirements.

[0181] Comparative Example 2

[0182] The difference from Example 1 is that in this example, the treatment solution in steps (2) and (5) is adjusted to 400-500 g / L of phosphoric acid, 10-30 g / L of sodium m-nitrobenzoate, and 5-10 g / L of pinacol quinoline borate.

[0183] Other processing methods are exactly the same as in Example 1, and will not be repeated here.

[0184] After the titanium etching process in step (6) is completed, the surface-treated titanium-aluminum composite part is observed under an optical microscope. It can be seen that the titanium surface is basically pore-free, while the aluminum shows continuous corrosion. The fact that there is basically no corrosion on the titanium, while the aluminum is severely corroded, indicates that although replacing sulfuric acid with phosphoric acid can remove the oxide film on the titanium, it also causes great damage to the oxide film on the aluminum. In the subsequent etching process, the current is concentrated on the aluminum, which intensifies the corrosion of the aluminum and causes more current to act on the aluminum again, forming a Matthew effect in current distribution, which leads to the corrosion of the aluminum and the titanium being basically pore-free.

[0185] As can be clearly seen from the above embodiments, after the titanium-aluminum composite film removal agent of the present invention is applied, a microporous layer with a pore size of 20-200 μm and a pore depth of 20-200 μm can be formed on the titanium after the film removal treatment, while there is basically no corrosion on the aluminum. After further processing, the microporous treatment of the titanium-aluminum composite is completed.

[0186] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style of the specification is merely for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0187] Based on the disclosure and teachings of the foregoing specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments described above, and any obvious improvements, substitutions, or modifications made by those skilled in the art based on the present invention are within the scope of protection of the present invention. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on the present invention.

Claims

1. A titanium-aluminum composite film removal agent, characterized in that: It includes an accelerator, a corrosion inhibitor, and a film stripping agent; the accelerator is selected from one or more of nitric acid, sodium nitrate, potassium nitrate, ferric nitrate, copper nitrate, manganese nitrate, cerium nitrate, nickel nitrate, ammonium nitrate, guanidine nitrate, urea nitrate, nitrobenzenesulfonic acid and its salts, and nitrobenzene acid and its salts; the corrosion inhibitor is at least one of pinacol quinoline borate, mercaptophenylprophiazole, and caprolactam; and the film stripping agent is selected from sulfuric acid. The titanium-aluminum composite is a composite formed by combining titanium alloy and aluminum alloy metal matrix. The decoction agent is used to remove the oxide film of titanium in the titanium-aluminum composite and causes little damage to the oxide film of aluminum.

2. The titanium-aluminum composite film removal agent as described in claim 1, characterized in that: The film removal agent is applied via chemical or electrochemical removal. Chemical immersion is performed at a temperature of 40–90°C for 30–300 seconds; electrochemical removal is performed at a temperature of 10–50°C for 6–60 minutes, with a voltage of 1–20V or a current density of 1–20A / dm³. 2 .

3. A method for treating micropores on the surface of a titanium-aluminum composite component, characterized in that, Includes the following steps: S1. Place the titanium-aluminum composite part in sulfuric acid or mixed acid solution and pass an electric current to perform anodic oxidation, so that an oxide film of a certain thickness is generated on the surface of the titanium-aluminum composite part. S2. The titanium-aluminum composite is subjected to a film removal treatment agent as described in any one of claims 1 to 2 to remove the oxide film on the titanium; and, before or after the film removal treatment, the titanium-aluminum composite is placed in an aluminum alloy sealing agent for sealing treatment. S3. Place the titanium-aluminum composite in a titanium etching solution for one or more anodic electrolytic etching treatments to create micropores on the titanium alloy. S4. The titanium-aluminum composite is subjected to conventional treatment to complete the microporous treatment of the surface of the titanium-aluminum composite. The conventional treatment includes at least one of alkaline washing, descaling, rinsing and drying.

4. The method for treating micropores on the surface of a titanium-aluminum composite component as described in claim 3, characterized in that, In step S3, the titanium etching solution includes halide ions, acid, positioning aid, and titanium corrosion inhibitor. The positioning aid includes positioning agents or fillers. The positioning agents include one or more of sodium saccharin, sodium allyl sulfonate, sodium vinyl sulfonate, tetraacetyl ethylenediamine, dicyclohexylamine, formamide, dimethylformamide, tetrahydroxypropyl ethylenediamine, and diethylpropynylamine. The fillers include one or more of ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, glycerin, polyglycerol, sorbitol, and mannitol. The titanium corrosion inhibitor includes one or more of iron ions, copper ions, sulfate ions, phosphate ions, nitrobenzoic acid, nitroaniline, alizarin, and quinoline.

5. The method for treating micropores on the surface of a titanium-aluminum composite component as described in claim 4, characterized in that, The halide ions include one or more of fluoride ions, chloride ions, bromide ions, and iodide ions; the acids include inorganic acids or organic acids, the inorganic acids include one or more of phosphoric acid, sulfonic acid, hydrofluoric acid, boric acid, fluoroboric acid, fluorozirconic acid, fluorotitanic acid, and fluorosilicic acid, and the organic acids include one or more of citric acid, malic acid, tartaric acid, lactic acid, oxalic acid, propionic acid, gluconic acid, acetic acid, alkyl sulfonic acid, benzoic acid, and amino acids.

6. The method for treating micropores on the surface of a titanium-aluminum composite component as described in claim 3, characterized in that, Step S3 further includes the following steps: S31. Perform aluminum stripping and anodizing treatment on titanium-aluminum composite parts; S32. Place the titanium-aluminum composite part in an aluminum chemical or electrochemical etching solution for one or more etching treatments to create micropores on the aluminum alloy.

7. The method for treating micropores on the surface of a titanium-aluminum composite component as described in claim 6, characterized in that, In step S3, the titanium-aluminum composite component is placed in a titanium etching solution for one or more anodic electrolytic etching treatments, under the following conditions: the titanium-aluminum composite component is placed in the titanium etching solution for anodic electrolytic etching for 5–30 min, wherein the anodic etching current is 1–10 A / dm. 2 The process is repeated 1 to 3 times at a temperature of 10 to 70°C to form a microporous layer with a depth of 20 to 200 μm and a diameter of 20 to 200 μm on the titanium surface of the titanium-aluminum composite.

8. The method for treating micropores on the surface of a titanium-aluminum composite component as described in claim 3, characterized in that, Before anodizing in step S1, the titanium-aluminum composite is placed in the titanium-aluminum composite stripping agent according to any one of claims 1 to 2 for stripping treatment.

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