An amorphous silicon dioxide coating prepared based on micro-arc oxidation and a preparation method and application thereof

Abstract

The application discloses an amorphous silicon dioxide coating prepared based on micro-arc oxidation, a preparation method and application thereof, and belongs to the technical field of metal surface protection and silicon dioxide coating. In the application, a magnesium alloy, an aluminum alloy, a titanium alloy, a titanium-aluminum base and a nickel-aluminum base are used as anodes and are placed in a micro-arc oxidation tank, a hydrolytic solution of organic silicon is used as an electrolyte, and an amorphous silicon dioxide coating with a thickness of more than 100 mu m can be prepared within 20 minutes through a step-by-step step-incremental constant potential control means. The application utilizes the advantages of the micro-arc oxidation process and the sol-gel process, avoids their shortcomings, and realizes the superimposed synergistic effect of "1+1>2". The process steps of the application are simple, and the application is very suitable for full-automatic operation and processing in industry. The amorphous silicon dioxide coating with the required thickness, wear resistance, corrosion resistance, erosion resistance, oxidation resistance and other characteristics can be prepared by changing the electrolyte concentration, the micro-arc oxidation time and the electric control parameters, or through the conventional micro-arc oxidation constant voltage and constant current control means.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of wear-resistant corrosion-resistant, erosion-resistant, oxidation-resistant amorphous silicon dioxide coating based on micro-arc oxidation preparation and method and application, belong to metal surface protection and silicon dioxide coating technical field. BACKGROUND

[0002] With the development of modern science and technology, human society puts forward higher and higher requirements on the performance of materials. In order to adapt to more application environments, many alloy materials (such as aluminum alloy, magnesium alloy, titanium alloy, titanium aluminum and nickel aluminum, etc.) are more and more dependent on the contribution of coating. Silicon, as the most abundant element in the earth's crust except oxygen, is classified as quasi-metal because it has both metallic and non-metallic properties. In addition, silicon dioxide (SiO2) film has good chemical stability, thermal stability, good light transmission, hardness, wear resistance and corrosion resistance, and is an ideal coating material and surface modification material, with broad application prospects. For these reasons, researchers have used many means to prepare silicon dioxide coating, such as preparing silicon dioxide coating by sol-gel method, chemical vapor deposition or plasma chemical vapor deposition, magnetron sputtering, ion sputtering, etc. Sol-gel process can also be used to prepare silicon dioxide coating on the surface of conventional anodic oxidation and micro-arc oxidation coating to form a composite coating. However, these silicon dioxide coating preparation methods are either complex or costly, and some of the coatings prepared by these methods are very thin or have poor adhesion, and some require long curing time or high temperature treatment that affects the properties of the substrate material.

[0003] Among them, sol-gel method can be used for surface treatment process of many materials, and the process steps generally include solution preparation (hydrolysis / polymerization), aging, drying and sintering. This method can improve the chemical uniformity of multi-component system, and the prepared coating has uniform composition and high purity. At present, there are many reports that many kinds of coatings with silicon dioxide as the main component have been prepared by this method. But their preparation process is time-consuming, the prepared sol has high concentration, and it is used only once and cannot be stored for a long time and used repeatedly. The bonding strength between the coating and the substrate is low, about 10 MPa.

[0004] Micro-arc oxidation (MAO) can generate ceramic coating on the surface of metals such as aluminum, magnesium and titanium alloy in situ. The technology has the advantages of good adhesion of the prepared coating, simple process, low cost and easy industrial production. However, the common electrolyte system of MAO is mainly silicate, phosphate and aluminate, and the control method is mainly constant current mode or constant voltage mode. The prepared coating is thin or time-consuming, and the main component is generally oxide and compound from electrolyte and substrate material. There is no report on the main component of MAO coating being silicon dioxide. In the conventional micro-arc oxidation process, it is difficult to prepare a coating with a thickness of more than 50 microns within half an hour. Even if a thick coating is prepared for a long time, the effective thickness is about 30 microns, and the surface thickening part is a loose and porous structure with low mechanical strength. The main component of the conventional micro-arc oxidation coating is metal oxide, which leads to the coating being easily dissolved in acid and alkali.

[0005] Based on the above existing background, the present application is proposed. SUMMARY

[0006] The primary object of the present application is to utilize the advantages of micro-arc oxidation and sol-gel process, avoid their shortcomings, achieve the superimposed synergistic effect of "1+1>2", and invent a method for preparing amorphous silicon dioxide coating with desired thickness, wear resistance, corrosion resistance, erosion resistance, oxidation resistance and other properties, which is simple in process steps, suitable for full-automatic operation and processing in industry, and can prepare amorphous silicon dioxide coating with desired thickness, wear resistance, corrosion resistance, erosion resistance, oxidation resistance and other properties by changing the electrolyte concentration, processing time and electric control parameters.

[0007] A method for preparing amorphous silicon dioxide coating based on micro-arc oxidation, which adopts micro-arc oxidation treatment of electrolyte containing organosilicon to prepare amorphous silicon dioxide coating.

[0008] The method, the electrolyte containing organosilicon comprises: organosilicon compound, alkali.

[0009] The method, the organosilicon compound includes at least one of tetraethyl silicate, silane coupling agent, silanol, silyl ether and silane; the alkali includes organic alkali and / or inorganic alkali, the organic alkali includes at least one of propylene diamine and diethylamine, and the inorganic alkali includes at least one of NaOH, KOH, ammonia water and alkaline ammonia salt.

[0010] Preferably, the concentration of organosilicon compound is 5-200 mL / L, the mass concentration of inorganic alkali is 0.5-50 g / L, the concentration of organic alkali is not more than 80 mL / L, and the electrolyte is prepared by using deionized water.

[0011] The method, the auxiliary additive includes at least one of phosphate, silicate, vanadate and the like, as well as coordination salt of rare earth element and colored ion, various oxides and high molecular particles.

[0012] Preferably, an auxiliary additive can also be added to the electrolyte, with a concentration of no more than 50 g / L.

[0013] The method requires the following for micro-arc oxidation treatment:

[0014] 1) Hang the pretreated workpiece into the micro-arc oxidation tank as the anode;

[0015] 2) The electrical control parameters for micro-arc oxidation processing: positive voltage 200-750V, negative voltage 0-250V, current density 5-50A / dm 2 , frequency 50-10000Hz, duty cycle 5-95%, positive and negative pulse number ratio (1-10):

[0016] (0-10);

[0017] 3) Adopt a segmented constant voltage mode in the positive direction, with an initial voltage of 200V, an increase or decrease of 10-200V each time, and a change duration of 1-20 minutes each time; or adopt a constant voltage mode or a constant current mode in the positive direction;

[0018] 4) Adopt a constant voltage or constant current mode in the negative direction, with a requirement that the average current intensity in the negative direction is not higher than that in the positive direction;

[0019] 5) Maintain the electrolyte temperature at no higher than 50℃.

[0020] The method requires that after the micro-arc oxidation treatment, the residual substances on the workpiece are cleaned and removed, and then naturally dried, blown dry, or oven dried.

[0021] The application also provides an amorphous silicon dioxide coating prepared based on micro-arc oxidation, which is prepared by the above method.

[0022] The application also provides an application of the amorphous silicon dioxide coating, which is used as a coating for a workpiece made of one of aluminum alloy, magnesium alloy, titanium alloy, titanium aluminum, and nickel aluminum.

[0023] The preparation method of the electrolyte is as follows:

[0024] 1) Add the reagents in the above order one by one, and confirm that the current solution in the container is clear and transparent without precipitation before adding the next reagent, and maintain the stirring function effective;

[0025] 2) The hydrolysis time of the organosilicon compound is controlled to be 0.5-24h;

[0026] Workpiece pretreatment: remove the stains on the surface of the workpiece by pickling, alkaline cleaning, sandblasting, or mechanical polishing, and clean and remove the impurities that may contaminate the electrolyte.

[0027] After the micro-arc oxidation treatment, the residues on the workpiece are removed by cleaning, and then the workpiece is naturally dried, or dried by blowing or drying, and the treatment temperature basically does not affect the mechanical properties of the base material.

[0028] The amorphous silicon dioxide coating prepared by the method has the advantages of wear resistance, corrosion resistance, erosion resistance and oxidation resistance, and the thickness of the coating is not more than 300 microns.

[0029] In the micro-arc oxidation process, physical and chemical reactions that are difficult to occur in the sol-gel method occur on the high-energy field micro-area of the surface of the workpiece, such as the conversion of hydrolyzed organic silicon attached to the surface of the workpiece into a SiO2 film, and the diffusion of activated particles O and Si adsorbed on the surface of the workpiece into the matrix to form a dense layer. Compared with the sol-gel preparation process, the present application has many advantages: 1) no high temperature or long time curing treatment is required, reducing the negative impact of over-aging on the performance of the base material; 2) ultra-thick coating can be prepared in a short time; 3) higher interfacial bonding strength; 4) the reaction solution can be stored for a long time and reused; 5) simple process, short preparation period, and easier industrialization.

[0030] The present application adopts a segmented constant voltage electric control mode, and uses organic silicon as the electrolyte by referring to the solution preparation method of the sol-gel method. Compared with the traditional micro-arc oxidation process, it has the following obvious characteristics: 1) the thickening rate of the coating is fast, and a coating with a thickness of more than 100 microns can be prepared in a short time; 2) the main component of the coating is SiO2; 3) the electrolyte can be stored for a long time and can be used for many different base materials.

[0031] The present application will be further described below with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a photo of the amorphous SiO2 coating with a thickness of 130 microns prepared in Example 1 for 23 minutes.

[0033] Figure 2 is the SEM surface morphology of the amorphous SiO2 coating with a thickness of 130 microns prepared in Example 1 for 23 minutes.

[0034] Figure 3 is the SEM cross-sectional morphology of the amorphous SiO2 coating with a thickness of 130 microns prepared in Example 1 for 23 minutes.

[0035] Figure 4 is the EDS energy spectrum analysis of the amorphous SiO2 coating with a thickness of 130 microns prepared in Example 1 for 23 minutes after polishing and thickness reduction to 60 microns.

[0036] Figure 5is the XRD analysis pattern comparison of the amorphous SiO2coating with a thickness of 130 μm prepared by 23 minutes in Example 1 and the 6061 base material.

[0037] Figure 6 is the polarization curve comparison of the amorphous SiO2coating with a thickness of 130 μm prepared by 23 minutes in Example 1 and the 6061 base material.

[0038] Figure 7 is the test result comparison of the amorphous SiO2coating prepared by 23 minutes in Example 1 using the organosilicon electrolyte, the coating prepared by 23 minutes in Comparative Example 1 using the phosphate system and the coating prepared by 23 minutes in Comparative Example 2 using the silicate system under the same friction and wear test conditions.

[0039] Figure 8 is the friction coefficient test comparison of the coating prepared in Example 1 and Comparative Examples 1 and 2. DETAILED DESCRIPTION

[0040] The present application will be described in more detail by specific examples below, but the scope of the present application is not limited to these examples.

[0041] Example 1:

[0042] a) Preparation of the organosilicon electrolyte:

[0043] 1) Prepare a 25 g / L NaOH solution. Add NaOH to high-purity deionized water, stir well until clear, and cool to room temperature for standby.

[0044] 2) Add 135 mL / L of tetraethyl silicate (TEOS), stop after mechanical stirring for 4 h under room temperature and closed environment, the conductivity is 18.53 mS / cm, and the pH is 11.8.

[0045] b) Workpiece pretreatment: cut the 6061 aluminum alloy plate into a size of 20 x 15 x 4 mm sample block, polish it to brightness with 1000 mesh sandpaper for standby.

[0046] c) Micro-arc oxidation processing:

[0047] 1) Set the electrical control parameters: frequency 1000 Hz, positive and negative pulse number ratio 1:0, positive duty cycle 5%, positive uses segmented constant voltage mode (initial voltage 400 V, holding time 5 minutes, voltage 430 V holding 2 minutes, voltage 460 V holding 2 minutes, voltage 480 V holding 2 minutes, voltage 500 V holding 2 minutes, voltage 520 V, holding 2 minutes, voltage 540 V, holding 2 minutes, voltage 560 V, holding 2 minutes, voltage 580 V, holding 2 minutes, voltage 600 V, holding 2 minutes); no load in negative direction.

[0048] 2) Use stainless steel electrolytic cell as cathode, use aluminum alloy rod as tooling, and place workpiece in the center of the electrolytic cell as anode.

[0049] 3) Maintain the temperature of the electrolyte below 40℃ by air stirring and cooling water circulation system.

[0050] d) Workpiece post-processing: after tap water rinsing, use deionized water ultrasonic cleaning for 10 minutes, and then dry with a hair dryer.

[0051] The sample obtained by the above steps is shown in the macroscopic photo Figure 1 , the microscopic morphology is shown in Figure 2 , the cross-sectional morphology of the sample is shown in Figure 3 , the surface coating thickness is 130 μm, and the coating thickness measured by ultrasonic thickness gauge is 130 ± 10 μm. Figure 4 EDS energy spectrum analysis of the amorphous SiO2 coating with a thickness of 130 μm thinned to 60 μm, as shown in the figure, the coating contains a small amount of elements contained in the base material. The XRD detection results of the 6061 aluminum alloy sample before and after micro-arc oxidation processing are shown in Figure 5 , and from the figure it can be seen that the main cost of the coating is amorphous SiO2. The polarization curve of the sample before and after micro-arc oxidation processing is shown in Figure 6 , and from the figure it can be seen that the corrosion current density after treatment decreases by 2 orders of magnitude, and the passivation region width is more than 3 times that before treatment.

[0052] Comparative Example 1:

[0053] a) Preparation of conventional micro-arc oxidation electrolyte:

[0054] 1) Prepare 4 g / L KOH solution. Add KOH to high-purity deionized water and stir thoroughly until clear.

[0055] 2) Add 5 g / L sodium silicate (Na2SiO3), and stir thoroughly until clear.

[0056] 3) Add 12 g / L sodium hexametaphosphate [(NaPO3)6], and stir magnetically until the solution is clear and transparent.

[0057] b) Workpiece pretreatment: cut the 6061 aluminum alloy plate into a size of 20 × 15 × 4 mm sample, and polish it with 1000 mesh sandpaper to make it bright for use.

[0058] c) Micro-arc oxidation processing:

[0059] 1) Electronic control parameter settings: frequency 1000Hz, positive to negative pulse ratio 1:0, positive duty cycle 20%, positive mode constant voltage (420V, duration 2 minutes) + constant current mode (current density 11.4A / dm²) 2 (Duration: 21 minutes). Negative loading is not performed.

[0060] 2) A stainless steel electrolytic cell is used as the cathode. An aluminum alloy rod is used as a tooling to place the workpiece in the center of the electrolytic cell as the anode.

[0061] 3) The electrolyte temperature is maintained below 50°C by agitating the electrolyte with air and by a cooling circulating water system.

[0062] d) Post-processing of workpieces: Rinse with tap water and then dry with a hair dryer.

[0063] Comparative Example 2:

[0064] a) Preparation of conventional micro-arc oxidation electrolyte:

[0065] 1) Prepare a 4 g / L KOH solution. Add KOH to high-purity deionized water and stir thoroughly until clear.

[0066] 2) Add 12 g / L of sodium silicate (Na2SiO3) and stir thoroughly until clear.

[0067] 3) Add 10 g / L of potassium fluoride (KF), stir magnetically for 6 hours, then stop and set aside.

[0068] b) Pre-treatment of workpieces: Cut 6061 aluminum alloy sheet into sample blocks with dimensions of 20×15×4mm, and polish them with 1000-grit sandpaper for later use.

[0069] c) Micro-arc oxidation processing:

[0070] 1) Electronic control parameter settings: frequency 100Hz, positive to negative pulse ratio 1:0, positive duty cycle 5%, positive constant voltage mode (voltage 250V, duration 5 minutes, voltage 350V, duration 5 minutes, voltage 400V, duration 5 minutes, voltage 450V, duration 5 minutes, voltage 250V, duration 3 minutes); negative constant voltage is not limited.

[0071] 2) A stainless steel electrolytic cell is used as the cathode. An aluminum alloy rod is used as a tooling to place the workpiece in the center of the electrolytic cell as the anode.

[0072] 3) The electrolyte temperature is maintained below 50°C by agitating the electrolyte with air and by a cooling circulating water system.

[0073] d) Workpiece post-processing: tap water rinse, then dry with a hair dryer.

[0074] Example 1, Comparative Example 1 and Comparative Example 2 were respectively treated by using silicone solution system, phosphate solution system and silicate solution system to perform micro-arc oxidation on 6061 aluminum alloy, and the treatment time was 23 minutes. The friction and wear test results are shown in Figure 7 and 8 The wear trace of the coating prepared in Example 1 is not obvious, while the wear of the Si3N4 counter friction ball is very serious. Under the same test conditions, the wear trace of the coating prepared in Comparative Examples 1 and 2 is very obvious, the coating has been worn out, the friction track has a metallic luster visible to the naked eye, a large amount of aluminum alloy substrate of the sample is peeled off and adhered to the surface of the Si3N4 counter friction ball, and the wear of the Si3N4 counter friction ball is obviously lighter than that of the Si3N4 counter friction ball used for friction of the coating prepared in Example 1. From the change of the friction coefficient, it can be seen that after the friction of the sample prepared in Example 1 is stabilized, the friction coefficient fluctuates little and gradually decreases, and self-lubrication phenomenon occurs.

[0075] Table 1: Comparison of the coating formed by Example 1 and conventional micro-arc oxidation (same preparation time)

[0076] Solution system Coating thickness Friction test duration Wear scar depth Wear rate Example 1 Silicone solution system 130 pm 20 min 22.62 pm 1.131 pm / min Comparative Example 1 Phosphate system 36 pm 20 min 11.8 min wear-through 3.051 pm / min Comparative Example 2 Silicate system 18 pm 20 min 6.6 min wear-through 2.727 pm / min

[0077] Example 2:

[0078] a) Preparation of silicone electrolyte:

[0079] 1) Prepare 25g / L NaOH solution. Add NaOH to high-purity deionized water, stir thoroughly until clear, and cool to room temperature for use.

[0080] 2) Add 135mL / L tetraethyl silicate (TEOS) under room temperature and sealed environment, and stop mechanical stirring after 2h.

[0081] 3) Dilute the solution concentration to 1 / 3 times. That is, add 2 times the volume of deionized water to the solution.

[0082] b) Workpiece pretreatment: cut the 6061 aluminum alloy plate into a size of 20x15x4mm sample, polish it to brightness with 1000 mesh sandpaper, and use it.

[0083] c) Micro-arc oxidation processing:

[0084] 1) Electric control parameter setting: frequency 1000 Hz, positive and negative pulse number ratio 1:0, positive duty cycle 5%, positive using segmented constant voltage mode (initial voltage 400 V, holding time 5 minutes, voltage 430 V for 2 minutes, voltage 460 V for 2 minutes, voltage 480 V for 2 minutes, voltage 500 V for 2 minutes, voltage 520 V, for 2 minutes, voltage 540 V, for 2 minutes, voltage 560 V, for 2 minutes, voltage 580 V, for 2 minutes, voltage 600 V, for 2 minutes); negative loading.

[0085] 2) Use stainless steel electrolytic cell as cathode, use aluminum alloy rod as tool, put the workpiece in the center of the electrolytic cell as anode.

[0086] 3) Maintain the electrolyte temperature below 40℃ by air stirring the electrolyte and cooling circulating water system.

[0087] d) Workpiece post-processing: after tap water flushing, use deionized water ultrasonic cleaning for 10 minutes, then dry with a hair dryer.

[0088] Example 3:

[0089] a) Preparation of organic silicon electrolyte:

[0090] 1) Prepare 25 g / L NaOH solution. Add NaOH to high-purity deionized water, stir well until clear, cool to room temperature for standby.

[0091] 2) Add 135 mL / L tetraethyl silicate (TEOS), stop mechanical stirring after 2 hours under room temperature and sealed environment.

[0092] 3) Dilute the solution concentration to 1 / 3 times. That is, add 2 times the volume of deionized water to the solution.

[0093] b) Workpiece pretreatment: cut 6061 aluminum alloy plate into 20x15x4mm size blocks, polish with 1000 mesh sandpaper and use.

[0094] c) Micro-arc oxidation processing:

[0095] 1) Electric control parameter setting: frequency 1000 Hz, positive and negative pulse number ratio 1:0, positive duty cycle 5%, positive using segmented constant voltage mode (initial voltage 300 V, holding time 5 minutes, voltage 330 V for 2 minutes, voltage 360 V for 2 minutes, voltage 390 V for 2 minutes, voltage 420 V for 2 minutes, voltage 450 V, for 2 minutes, voltage 480 V, for 2 minutes, voltage 510 V, for 2 minutes, voltage 540 V, for 2 minutes, voltage 300 V, for 2 minutes), negative loading.

[0096] 2) Use stainless steel electrolytic cell as cathode, use aluminum alloy rod as tool, put workpiece in the center of electrolytic cell as anode.

[0097] 3) Maintain the temperature of electrolyte below 40℃ by air stirring and cooling circulating water system.

[0098] d) Workpiece post-processing: after tap water rinsing, use deionized water ultrasonic cleaning for 10 minutes, then dry with hair dryer.

[0099] Example 4:

[0100] a) Preparation of organic silicon electrolyte:

[0101] 1) Prepare 25g / L NaOH solution. Add NaOH to high-purity deionized water, stir well until clear, cool to room temperature for standby.

[0102] 2) Add 135mL / L tetraethyl silicate (TEOS), stop mechanical stirring after 2h under room temperature and sealed environment.

[0103] 3) Dilute the solution concentration to 1 / 3 times. That is, add 2 times volume of deionized water to the solution.

[0104] b) Workpiece pretreatment: cut 6061 aluminum alloy plate into 20x15x4mm size blocks, polish with 1000 mesh sandpaper to bright finish for standby.

[0105] c) Micro-arc oxidation processing:

[0106] 1) Set the frequency to 1000Hz, the ratio of positive and negative pulse number to 1:0, the positive duty cycle to 20%, the positive to constant current mode, the current density to 11.4A / dm 2 , time 23 minutes; negative not loaded.

[0107] 2) Use stainless steel electrolytic cell as cathode, use aluminum alloy rod as tool, put workpiece in the center of electrolytic cell as anode.

[0108] 3) Maintain the temperature of electrolyte below 40℃ by air stirring and cooling circulating water system.

[0109] d) Workpiece post-processing: after tap water rinsing, use deionized water ultrasonic cleaning for 10 minutes, then dry with hair dryer.

[0110] Example 5:

[0111] a) Preparation of organic silicon electrolyte:

[0112] 1) Preparation of 25g / L NaOH solution. NaOH was added to high purity deionized water, stirred thoroughly until clear, and cooled to room temperature for standby.

[0113] 2) Add 135 mL / L of tetraethyl silicate (TEOS), stop after 12 hours of mechanical stirring under room temperature and closed environment for standby.

[0114] b) Workpiece pretreatment: AZ31B magnesium alloy plate was cut into 20x15x4mm blocks, polished with 1000 grit sandpaper, and used as standby.

[0115] c) Micro-arc oxidation processing:

[0116] 1) Control parameter setting: frequency 1000 Hz, positive and negative pulse ratio 1:0, positive duty cycle 10%, positive using segmented constant voltage mode (initial voltage 400V, holding time 5 minutes, voltage 420V holding 2 minutes, voltage 440V holding 2 minutes, voltage 460V holding 2 minutes, voltage 480V holding 2 minutes, voltage 500V, holding 2 minutes, voltage 480V, holding 2 minutes, voltage 460V, holding 2 minutes, voltage 400V, holding 4 minutes; negative not loaded.

[0117] 2) Use stainless steel electrolytic cell as cathode, use aluminum alloy rod as tooling, and place the workpiece in the center of the electrolytic cell as anode.

[0118] 3) Maintain the electrolyte temperature below 25°C by air stirring the electrolyte and a cooling circulating water system.

[0119] d) Workpiece post-processing: after flushing with tap water, use deionized water to ultrasonic clean for 10 minutes, and then dry with a hair dryer.

[0120] Example 6:

[0121] a) Preparation of organic silicon electrolyte:

[0122] 1) Preparation of 25g / L NaOH solution. NaOH was added to high purity deionized water, stirred thoroughly until clear, and cooled to room temperature for standby.

[0123] 2) Add 135 mL / L of tetraethyl silicate (TEOS), stop after 4 hours of mechanical stirring under room temperature and closed environment for standby, conductivity 18.53 mS / cm, pH = 11.8.

[0124] b) Workpiece pretreatment: 7N01 aluminum alloy plate was cut into 20x15x4mm blocks, polished with 1000 grit sandpaper, and used as standby.

[0125] c) Micro-arc oxidation processing:

[0126] 1) Electric control parameter setting: frequency 1000Hz, positive and negative pulse number ratio 1:0, positive duty cycle 5%, positive adopts segmented constant voltage mode (initial voltage 400V, holding time 5 minutes, voltage 430V holding 2 minutes, voltage 460V holding 2 minutes, voltage 480V holding 2 minutes, voltage 500V holding 2 minutes, voltage 520V, holding 2 minutes, voltage 540V, holding 2 minutes, voltage 560V, holding 2 minutes, voltage 580V, holding 2 minutes, voltage 600V, holding 2 minutes), negative does not load.

[0127] 2) Adopt stainless steel electrolytic cell as cathode, use Aluminum alloy rod as tool, the workpiece is placed in the center of the electrolytic cell as anode.

[0128] 3) Through air stirring electrolyte, and cooling circulating water system maintains the electrolyte temperature below 40 DEG C.

[0129] d) Workpiece post-processing: after tap water flushing, use deionized water ultrasonic cleaning 10 minutes, then use hair dryer to dry.

[0130] Table 2 electrolyte concentration and electric control parameter on the surface coating thickness of different materials

[0131]

[0132] It can be seen that the amorphous silicon dioxide coating prepared by the organic electrolyte solution has better wear resistance than the coating prepared by the conventional micro-arc oxidation electrolyte solution. The application can be applied to the surface ceramic treatment of various substrate materials, and the thickness of the coating can be controlled.

[0133] Although the content of the application has been described in detail by the above examples, it should be recognized that the description of the above examples should not be considered as a limitation of the application.

Claims

1. A method for preparing an amorphous silicon dioxide coating based on micro-arc oxidation, characterized in that, An amorphous silicon dioxide coating was prepared by micro-arc oxidation using an electrolyte containing organosilicon. The electrolyte containing organosilicon comprises: an organosilicon compound and an alkali; the organosilicon compound includes at least one of silicate ester, silanol, and silane; the alkali includes organic alkali and / or inorganic alkali, the organic alkali including at least one of propylenediamine, diethylamine, etc., and the inorganic alkali including at least one of NaOH, KOH, ammonia, alkaline ammonium salt, etc.; the concentration of the organosilicon compound is 5-200 mL / L, the mass concentration of the inorganic alkali is 0.5-50 g / L, the concentration of the organic alkali does not exceed 80 mL / L, and the electrolyte is prepared using deionized water.

2. The method according to claim 1, characterized in that, The requirements for micro-arc oxidation are as follows: 1) The pre-treated workpiece is hung in the micro-arc oxidation tank as the anode; 2) The electrical control parameters for micro-arc oxidation are: positive voltage 200~750V, negative voltage 0~250V, and current density 5~50A / dm³. 2 The frequency is 50-10000Hz, the duty cycle is 5-95%, and the ratio of positive to negative pulses is (1-10):(0-10); 3) The positive direction adopts a segmented constant voltage mode, with an initial voltage of 200V, which is increased or decreased by 10-200V each time, and each change is maintained for 1-20 minutes. 4) Use constant voltage or constant current mode for the positive direction; 5) Use constant voltage or constant current mode for the negative direction, requiring the average current intensity of the negative direction to be no higher than the average current intensity of the positive direction; 6) Maintain the electrolyte temperature to be no higher than 50℃.

3. The method according to claim 1, characterized in that, After cleaning and removing residues from the workpiece using micro-arc oxidation, it is allowed to air dry, or blow-dry or oven-dry.

4. An amorphous silicon dioxide coating prepared based on micro-arc oxidation, characterized in that, Prepared by the method described in any one of claims 1 to 3.

5. The application of the amorphous silicon dioxide coating according to claim 4, characterized in that, Coatings for workpieces whose base material is one of aluminum alloy, magnesium alloy, titanium alloy, titanium aluminum, and nickel aluminum.

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