A pure zinc material and its preparation method and application

Abstract

The present invention relates to the field of coating materials and discloses a pure zinc material, its preparation method, and its application. The pure zinc material of the present invention has a coating formed on its surface by micro-arc oxidation using a sodium phosphate and sodium stannate electrolyte, and an electrode with a connecting wire is provided on the coating. The present invention uses a composite electrolyte of sodium phosphate and sodium stannate to perform micro-arc oxidation, forming a SnO2 / ZnO coating on the surface of the pure zinc material that can be used for formaldehyde detection. By providing electrodes and utilizing the principle of oxygen adsorption-desorption for detection, the coating exhibits significantly superior sensitivity to formaldehyde compared to conventional gases, enabling effective, real-time, and simple formaldehyde detection.

Description

Technical Field

[0001] The present invention relates to the field of coating materials, and in particular to a pure zinc material and a preparation method and application thereof. Background Art

[0002] Formaldehyde, an industrial chemical, is widely used in the healthcare, home decoration, agriculture, chemical, wood, textile, and other industries. Various adhesives, coatings, and paints used in residential and commercial building renovations contain formaldehyde, and volatile formaldehyde becomes one of the main indoor pollutants. Formaldehyde has been identified by the World Health Organization as a carcinogen and teratogen. Long-term exposure to formaldehyde can cause chronic respiratory diseases, pregnancy syndrome, leukemia, and other diseases. As people's living standards continue to improve, they are paying more and more attention to environmental health, making the monitoring of toxic gases particularly important.

[0003] Currently, conventional methods for detecting formaldehyde gas have been established, including electrochemistry, high-performance liquid chromatography, gas chromatography, spectrophotometry, polarography, and fluorescence. Although these methods are widely used, their large-scale application is still limited due to their high cost, complex operation, and especially their unsuitability for real-time detection. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide a pure zinc material that can be used for formaldehyde detection and has high sensitivity to formaldehyde;

[0005] Another object of the present invention is to provide a method for preparing the above-mentioned pure zinc material and its application in detecting formaldehyde and preparing formaldehyde detection products.

[0006] In order to solve the above technical problems or at least partially solve the above technical problems, the present invention provides a method for solving the above technical problems or at least partially solving the above technical problems. The present invention provides a pure zinc material, on the surface of which there is a coating formed by micro-arc oxidation with sodium phosphate and sodium stannate electrolyte, and an electrode with a connecting wire is provided on the coating.

[0007] In certain embodiments of the present invention, the Zn content in the pure zinc material is ≥99.99%. In other embodiments of the present invention, the pure zinc material is No. 0 pure zinc. More specifically, the elemental composition (mass fraction) of No. 0 pure zinc is: Al 0.001%, Mg 0.0003%, Fe 0.001%, Cu 0.003%, Pb 0.0005%, Cd 0.0001%, Sn 0.0002%, and Zn ≥99.99%.

[0008] In certain embodiments of the present invention, the electrodes are interdigitated electrodes, and the wires are conductive metal wires, such as copper wires.

[0009] In certain embodiments of the present invention, the concentrations of sodium phosphate and sodium stannate in the electrolyte are independently selected from 1 to 10 g / L; in other embodiments of the present invention, the concentrations of sodium phosphate and sodium stannate in the electrolyte are both 5 g / L.

[0010] At the same time, the present invention also provides a method for preparing the pure zinc material, comprising:

[0011] Step 1: Pre-treatment of pure zinc material by grinding, degreasing and cleaning;

[0012] Step 2: The pretreated pure zinc material is used as the positive electrode and subjected to micro-arc oxidation in sodium phosphate and sodium stannate electrolyte to form a coating;

[0013] Step 3: forming electrodes on the surface of the coating by an ion sputtering process, and then connecting wires to the electrodes.

[0014] The micro-arc oxidation time can be selected according to actual circumstances. In some embodiments of the present invention, the micro-arc oxidation time is 4-6 minutes, while in other embodiments, the micro-arc oxidation time is 5 minutes.

[0015] In certain embodiments of the present invention, step 1 is:

[0016] The pure zinc material is polished in stages, ultrasonically cleaned with acetone, anhydrous ethanol, and water, and then degreased and cleaned with an alkaline degreasing solution. The polishing is performed using silicon carbide sandpaper of increasing grades until the surface is shiny, scratch-free, and has a consistent grain. The alkaline degreasing solution is sodium hydroxide, preferably a 10% sodium hydroxide solution.

[0017] Considering that large arc discharge in the later stage of constant current mode is easy to break down the coating, which will cause the surface quality of the coating to deteriorate, in certain embodiments of the present invention, the micro-arc oxidation is carried out in AC constant voltage mode. The prepared coating has more uniform thickness, high porosity, and large specific surface area, which is conducive to formaldehyde detection.

[0018] In other embodiments of the present invention, in the AC constant voltage mode, the forward voltage is +190V to +220V, optionally +210V; the negative voltage is -20V to -10V, optionally -10V; the pulse frequency is fixed at 0.1 to 0.3Hz, optionally 0.2Hz; the duty cycle is set to 70% to 90%, optionally 80%. In other embodiments of the present invention, in the AC constant voltage mode, the voltage is boosted starting from 0V and increasing by 10V until the preset value is reached, with the positive and negative voltages being boosted synchronously.

[0019] In certain embodiments of the present invention, pure zinc material is used as the positive electrode and other suitable metals such as stainless steel are used as the negative electrode, and the distance between the positive and negative electrodes is controlled at 10 cm; the temperature of the sodium phosphate electrolyte is controlled by an internal and external circulation refrigeration device to maintain it at 20-35°C.

[0020] In certain embodiments of the present invention, the electrodes are covered on the surface coating of the pure zinc material using a mask, and interdigitated electrodes are prepared by an ion sputtering process; the wires are adhered to the electrodes by conductive silver paste or other conductive materials to form connections.

[0021] In some other embodiments of the present invention, the ion sputtering process adopts a cyclic sputtering method, and the sputtering time and the number of cycles are adjusted according to the required shape of the interdigitated electrode; in some other embodiments of the present invention, the sputtering time is 90s and the number of cycles is 6 cycles.

[0022] The pure zinc material described in this invention detects formaldehyde gas based on the resistance change of the metal oxide formed on the surface by micro-arc oxidation when exposed to air and formaldehyde gas, based on the "oxygen adsorption-desorption" principle of metal oxides. When the pure zinc material is exposed to air, oxygen captures free electrons in the surface coating of the pure zinc material to form adsorbed oxygen, resulting in an increase in resistance. When formaldehyde is exposed to the surface coating of the pure zinc material, the formaldehyde and adsorbed oxygen undergo a redox reaction, releasing the captured electrons and reducing the resistance. The equation is as follows:

[0023] HCHO ads +2O - ads →CO2+H2O gas +2e -

[0024] In a comparison of common volatile gases that need to be detected urgently, such as ethanol, formaldehyde, and triethylamine, the pure zinc material of the present invention was used to detect the responsivity of each gas. The results showed that the resistivity sensitivity (K=Ra / Rg) of formaldehyde was as high as over 7, while the sensitivity values of several other test substances were only around 1. This shows that the SnO2 / ZnO coating on the surface of the pure zinc material of the present invention not only has a high sensitivity to formaldehyde, but also has good selectivity and reduces interference.

[0025] Based on the high sensitivity of the above-mentioned pure zinc material to formaldehyde, the present invention proposes the use of the pure zinc material in detecting formaldehyde or in preparing a formaldehyde detection product.

[0026] According to the provided application, the present invention provides a product for detecting formaldehyde, including a device for recording changes in resistance values and the pure zinc material of the present invention.

[0027] In certain embodiments of the present invention, the device for recording the change in resistance value includes a multimeter and a data processor, wherein the multimeter can be a digital multimeter and the data processor can be a computer device.

[0028] At the same time, the present invention also provides a method for detecting formaldehyde, which comprises placing the pure zinc material of the present invention in formaldehyde standard samples of different concentrations, and establishing a standard curve between resistance change data and formaldehyde concentration through a device that records resistance value changes; then placing the pure zinc material in a test environment, obtaining resistance value change data, and obtaining the formaldehyde concentration in the test environment through the standard curve.

[0029] It can be seen from the above technical solution that the present invention uses a composite electrolyte of sodium phosphate and sodium stannate to perform micro-arc oxidation to form a SnO2 / ZnO coating on the surface of a pure zinc material that can be used for formaldehyde detection. By setting electrodes and utilizing the oxygen adsorption-desorption principle for detection, it exhibits extremely excellent sensitivity to formaldehyde compared to conventional gases, and therefore can effectively, real-time, and simply detect formaldehyde. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Shown is a process flow chart of pure zinc material coating of the present invention;

[0031] Figure 2 The figures show the SEM results of the pure zinc material coating of the present invention; wherein, a and b are the SEM observation results of different areas;

[0032] Figure 3 The figure shows the composition diagram of the detection system for gas selectivity test;

[0033] Figure 4 Shown is a line graph of the Ra / Rg value of formaldehyde under different heating temperature conditions;

[0034] Figure 5 Shown is a bar graph of Ra / Rg values for different test gases;

[0035] Figure 6 The figure shows the Ra / Rg value variation of formaldehyde, ethanol and triethylamine. ac represents the broken lines of formaldehyde, ethanol and triethylamine respectively.

[0036] Figure 7 The figure shows the fitting curve of the pure zinc material of the present invention for detecting formaldehyde;

[0037] Figure 8 Shown are the SEM results of the surface coating of pure zinc material prepared with an electrolyte of 25 g / L sodium phosphate. DETAILED DESCRIPTION

[0038] The present invention discloses a pure zinc material, a preparation method, and an application thereof. Those skilled in the art can refer to the contents of this document and appropriately improve the process parameters to achieve the desired results. It should be noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in the present invention. The pure zinc material, preparation method, and application thereof of the present invention have been described through preferred embodiments. It is obvious that relevant personnel can modify or appropriately change and combine the pure zinc material, preparation method, and application thereof described herein without departing from the content, spirit, and scope of the present invention to implement and apply the technology of the present invention.

[0039] The present invention specifically provides a method for preparing the pure zinc material and the pure zinc material prepared therefrom, comprising:

[0040] 1. Pretreatment of pure zinc substrate

[0041] The pure zinc is cut, polished, and cleaned to obtain clean pure zinc, which is then immersed in a degreasing solution and then ultrasonically cleaned. The pure zinc is taken out, cleaned, and then blown dry to obtain pure zinc after pretreatment.

[0042] 2. Prepare micro-arc oxidation electrolyte

[0043] Dissolve sodium stannate and sodium phosphate in deionized water and stir evenly to obtain a micro-arc oxidation electrolyte;

[0044] 3. Micro-arc oxidation

[0045] The pure zinc after surface pretreatment is placed in a micro-arc oxidation electrolyte, wherein the pure zinc is connected to the positive electrode of the power supply as the positive electrode, and the stainless steel electrolytic cell is connected to the negative electrode of the power supply as the cathode; the heat dissipation device is turned on to control the temperature; and the micro-arc oxidation power supply is used to start power supply. In a constant voltage mode, the voltage is +190V to +220V, -20V to -10V, the pulse frequency is fixed at 0.1 to 0.3Hz, and the duty cycle is set to 70% to 90%, thereby obtaining pure zinc with a micro-arc oxidation coating on the surface.

[0046] 4. Ion sputtering

[0047] The mask was covered on the surface of the micro-arc oxidation coating and fixed in a vacuum ion sputtering instrument. The sputtering current was controlled constant and the interdigitated electrodes were prepared by a cyclic sputtering method. Each sputtering lasted 90 seconds, and a total of 6 cycles were sputtered.

[0048] 5. Copper wire adhesion

[0049] After sputtering, a multimeter is used to test the conductivity and processing quality of the interdigital electrodes. Then, conductive silver paste is used to stick the copper wires on the interdigital electrodes and dried to ensure good contact of the sensor circuit.

[0050] Unless otherwise specified, the experimental environment and parameter conditions of each group in the specific embodiment tests remain consistent except for the differences explicitly stated.

[0051] The following further describes a medical pure zinc material provided by the present invention, its preparation method and application.

[0052] Example 1: Preparation of pure zinc material for formaldehyde detection of the present invention

[0053] 1. Preparation method

[0054] 1. Pretreatment of pure zinc substrate

[0055] The pure zinc substrate is No. 0 zinc, whose elemental composition (mass fraction) is: Al 0.001%, Mg 0.0003%, Fe 0.001%, Cu 0.003%, Pb 0.0005%, Cd 0.0001%, Sn 0.0002%, and Zn ≥ 99.99%. The pure zinc substrate is cut into 25 mm × 25 mm × 2 mm pieces using wire cutting, and then polished with silicon carbide sandpaper from 400# to 800# to 1000# to 2000# to achieve a bright surface with no obvious scratches and consistent texture. The substrate is then ultrasonically cleaned in acetone, anhydrous ethanol, and deionized water for 10 minutes each, and air-dried with a hair dryer to obtain the pretreated pure zinc substrate.

[0056] The bright and clean pure zinc was immersed in a degreasing solution, which was a 10% sodium hydroxide solution at 60°C, and then ultrasonically cleaned for 10 minutes. The pure zinc was taken out and washed with clean water three times, and then dried with a hair dryer to obtain a pure zinc substrate after ultrasonic treatment.

[0057] 2. Prepare micro-arc oxidation electrolyte

[0058] The formula of the micro-arc oxidation electrolyte is 5g / L sodium stannate and 5g / L sodium phosphate. When preparing, first add 3L of deionized water to the electrolytic cell, then add 15g of sodium stannate and 15g of sodium phosphate and dissolve them fully. The micro-arc oxidation electrolyte needs to be replaced every time a micro-arc oxidation operation is performed, and each prepared micro-arc oxidation electrolyte must be used within 24 hours to prevent the micro-arc oxidation electrolyte from deteriorating;

[0059] 3. Micro-arc oxidation

[0060] The pure zinc after surface pretreatment is placed in a micro-arc oxidation electrolyte, wherein the pure zinc is connected to the positive electrode of the power supply as the positive electrode, and the stainless steel electrolytic cell is connected to the negative electrode of the power supply as the cathode, and the distance between the positive and negative electrodes is controlled at 10 cm; the refrigeration device is turned on and the temperature is controlled at 30°C; the micro-arc oxidation AC pulse power supply is used to start power supply, and in constant voltage mode, the voltages are +210V and -10V respectively, and the boost mode starts from 0V and increases by 10V step by step, in the positive and negative directions simultaneously, while the voltage reduction should be fast and can be directly shut down, which can make the prepared micro-arc oxidation coating have better quality and also protect the micro-arc oxidation power supply; the pulse frequency is fixed at 0.2Hz, the duty cycle is set to 80%, and the micro-arc oxidation time is 5min, after which pure zinc with a micro-arc oxidation coating on the surface is obtained;

[0061] 4. Ion sputtering

[0062] The mask was covered on the surface of the micro-arc oxidation coating and fixed in a vacuum ion sputtering instrument. The sputtering current was controlled constant and the interdigitated electrodes were prepared by a cyclic sputtering method. Each sputtering lasted 90 seconds, and a total of 6 cycles were sputtered.

[0063] 5. Copper wire adhesion

[0064] After sputtering, a multimeter was used to test the conductivity and the processing quality of the interdigital electrodes. Then, copper wires were bonded to the interdigital electrodes using conductive silver paste and dried at 80°C for 2 hours to ensure good contact between the sensor circuits.

[0065] The flow chart of preparing the pure zinc material by micro-arc oxidation in the present invention is shown in Figure 1 . Figure 2 is the SEM test result, Figure 2 From a to b, it can be seen that micron-sized pores are evenly distributed on the coating surface, there are no visible defects on the surface, the porosity is high, and the specific surface area is large, which is conducive to formaldehyde detection.

[0066] Example 2: Gas selectivity test and fitting curve

[0067] 1. Gas selectivity test

[0068] Reference Figure 3 The detection system shown in the figure is tested. A heating platform is set in a confined space, and the micro-arc oxidation method of the present invention is set on the platform to prepare the pure zinc material. Copper wires are adhered to the interdigital electrodes through conductive silver paste and connected to a multimeter. Data transmission is established between the multimeter and the computer.

[0069] A fixed amount of volatile gas solution is injected into the confined space. The solution is quickly volatilized into gas by the heating platform. The gas reacts with the sensor to generate a signal. The thermometer is used to indicate the temperature of the confined space. The fan is used to quickly exhaust the volatile gas after the test is completed.

[0070] See the results Figure 4-5 ; Figure 4 The results showed that under different heating temperature conditions, the Ra / Rg value of formaldehyde gradually increased and reached the highest at 225℃; Figure 5 The results showed that at 225°C and a concentration of 50 ppm, the Ra / Rg value of formaldehyde among various volatile gases was significantly higher than that of several other volatile gases, indicating that it has extremely high sensitivity and strong selectivity for formaldehyde.

[0071] 2. Supplementary information on gas selectivity test

[0072] Refer to the above detection system of this embodiment. When the sensor stabilizes at the preset temperature, a solution of the preset gas (50ppm formaldehyde / ethanol / triethylamine) is added dropwise. Here, Ra=1179Ω, Rg=131.52Ω, and the calculated Ra / Rg value is about 8.964; ethanol is set to Ra=1795.7Ω, R=1677.9Ω, and the calculated sensitivity is about 1.07; triethylamine is set to Ra=1268Ω, R=1134.1Ω, and the calculated sensitivity is about 1.118. The comparison of the resistance changes of the three is shown in the figure. Figure 6 .Depend on Figure 6 The results can be seen intuitively, indicating that the SnO2 / ZnO coating on the surface of the pure zinc material of the present invention not only has a high sensitivity to formaldehyde, but also has good selectivity and reduces interference.

[0073] 3. Fitting curve

[0074] Refer to the above detection system of this embodiment, and start adding formaldehyde solution of different concentrations (10ppm\20ppm\30ppm\40ppm\50ppm) after the sensor stabilizes at the preset temperature. Figure 7 The results show that the SnO2 / ZnO coating on the surface of the pure zinc material of the present invention has a good linear relationship for the detection of formaldehyde (R 2 =0.995), which has great potential in quantitative gas analysis.

[0075] Example 3: Effects of different electrolytes on pure zinc coating

[0076] Referring to the preparation method of Example 1, the difference is that the electrolyte is adjusted to 25g / L sodium phosphate. The SEM results of the prepared surface coating are shown in FIG. Figure 8 ;Depend on Figure 8 It can be seen that the film quality is poor, there are obvious cracks on the surface of the film layer, and the coating quality is obviously inferior to the coating quality in Example 1, which is very unfavorable for the induction detection of formaldehyde.

[0077] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A pure zinc material, characterized in that: A coating formed by micro-arc oxidation in an electrolyte of sodium phosphate and sodium stannate is provided on the surface of a pure zinc material, and interdigital electrodes with connecting wires are provided on the coating; the Zn content in the pure zinc material is ≥99.99%, and the concentrations of sodium phosphate and sodium stannate in the electrolyte are independently selected from 1 to 10 g / L.

2. The pure zinc material according to claim 1, characterized in that: The conducting wire is a copper wire.

3. Use of the pure zinc material according to any one of claims 1 to 2 in detecting formaldehyde or in preparing a formaldehyde detection product.

4. The method for preparing the pure zinc material according to claim 1, characterized in that: include: Step 1: Pre-treatment of pure zinc material by grinding, degreasing and cleaning; Step 2: The pretreated pure zinc material is used as the positive electrode and subjected to micro-arc oxidation in sodium phosphate and sodium stannate electrolyte to form a coating; Step 3: forming electrodes on the surface of the coating by an ion sputtering process, and then connecting wires to the electrodes.

5. A product for detecting formaldehyde, characterized in that: The invention comprises a device for recording changes in resistance value and the pure zinc material according to any one of claims 1 to 2.

6. The product according to claim 5, characterized in that: The device for recording the change of resistance value includes a multimeter and a data processor.

7. A method for detecting formaldehyde, characterized in that: The pure zinc material according to any one of claims 1 to 2 is placed in formaldehyde standard samples of different concentrations, and a standard curve of resistance change data and formaldehyde concentration is established by a device that records resistance value changes; then the pure zinc material is placed in a test environment, resistance value change data is obtained, and the formaldehyde concentration in the test environment is obtained through the standard curve.

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