阅读说明：本技术 一种利用离散晶核提高脱模剂涂覆均匀性的方法 (Method for improving coating uniformity of release agent by using discrete crystal nuclei ) 是由 杨光 李月 陈菊 惠越 于 2021-06-21 设计创作，主要内容包括：一种利用离散晶核提高脱模剂涂覆均匀性的方法,涉及离散晶核和工业涂覆技术领域。包括以下步骤：1)配制脱模剂溶液：在烧杯中加入去离子水,将重铬酸钾粉末加入烧杯中,搅拌；2)配置电镀液：将硫酸铬、氯化铵、硼酸、甘氨酸药品加入电沉积槽中,然后向槽中加入去离子水,搅拌。3)电沉积Cr离散晶核：将铜片固定在阴极板上接入电源负极,以钛篮为阳极接入电源正极,调节电流大小,调节加热温度,进行电沉积得Cr金属的离散晶核,根据极化曲线计算芯模表面的晶核密度。有利于重铬酸钾溶液在铜表面附着,增加涂覆均匀性,为铜模电铸脱模提供更有利的条件。离散晶核可以使用多次。对于精密电铸模具,实施简单,脱模后可获得镜面级表面质量。(A method for improving the coating uniformity of a release agent by using discrete crystal nuclei relates to the technical field of discrete crystal nuclei and industrial coating. The method comprises the following steps: 1) preparing a release agent solution: adding deionized water into a beaker, adding potassium dichromate powder into the beaker, and stirring; 2) preparing an electroplating solution: chromium sulfate, ammonium chloride, boric acid and glycine are added into an electrodeposition tank, and then deionized water is added into the tank and stirred. 3) Electro-deposition of Cr discrete nuclei: fixing a copper sheet on a negative plate, connecting a power supply cathode, connecting a titanium basket as an anode, connecting a power supply anode, adjusting the current, adjusting the heating temperature, performing electrodeposition to obtain discrete crystal nuclei of Cr metal, and calculating the crystal nucleus density on the surface of a core mold according to a polarization curve. The method is favorable for the adhesion of potassium dichromate solution on the surface of copper, increases the coating uniformity and provides more favorable conditions for the electroforming and demolding of the copper mold. The discrete crystal nuclei can be used many times. For a precise electroforming mold, the implementation is simple, and the surface quality of a mirror surface grade can be obtained after demolding.)

1. A method for improving the uniformity of application of a release agent using discrete crystal nuclei, comprising the steps of:

1) preparing a release agent solution: adding deionized water into a beaker, adding potassium dichromate powder into the beaker, and stirring;

2) preparing an electroplating solution: adding chromium sulfate, ammonium chloride, boric acid and glycine into an electrodeposition tank, then adding deionized water into the tank, and stirring;

3) electro-deposition of Cr discrete nuclei: fixing a copper sheet on a negative plate, connecting a power supply cathode, connecting a titanium basket as an anode, connecting a power supply anode, adjusting the current, adjusting the heating temperature, performing electrodeposition to obtain discrete crystal nuclei of Cr metal, and calculating the crystal nucleus density on the surface of a core mold according to a polarization curve.

2. The method for improving the coating uniformity of the release agent by using the discrete crystal nuclei as claimed in claim 1, wherein in the step 1), the temperature of the deionized water is 20 to 25 ℃.

3. The method for improving the coating uniformity of the release agent by using the discrete crystal nuclei as claimed in claim 1, wherein in the step 1), the potassium dichromate is added in an amount of 5 to 10 percent by mass of water; the mass-volume concentration of the potassium dichromate can be 50g/L to 100 g/L.

4. The method for improving the coating uniformity of the release agent by using the discrete crystal nuclei as claimed in claim 1, wherein in the step 1), the obtained release agent solution is left standing for 1 hour at the temperature of 20-25 ℃.

5. The method for improving the coating uniformity of the mold release agent by using the discrete crystal nuclei as claimed in claim 1, wherein in the step 2), the mass-volume concentration of the chromium sulfate may be 20g/L to 40g/L, the mass-volume concentration of the ammonium chloride may be 200g/L to 400g/L, the mass-volume concentration of the boric acid may be 60g/L to 100g/L, and the mass-volume concentration of the glycine may be 20g/L to 50 g/L.

6. The method for improving the coating uniformity of the release agent by using the discrete crystal nuclei as claimed in claim 1, wherein in the step 2), the temperature of the deionized water is 20-25 ℃; the pH of the obtained electroplating solution is 3.0-3.5.

7. The method for improving the coating uniformity of the release agent by using the discrete crystal nuclei as claimed in claim 1, wherein in the step 2), the obtained electroplating solution is left standing for 8-15 h at 20-25 ℃.

8. The method for improving the coating uniformity of the mold release agent by using the discrete crystal nuclei as claimed in claim 1, wherein in the step 3), the current density is 5 to 10A/dm²(ii) a The time of the electrodeposition is 5-15 s.

9. The method for improving the coating uniformity of the mold release agent by using the discrete crystal nuclei as claimed in claim 1, wherein the heating temperature in the step 3) is 40 to 50 ℃.

10. A method for improving the uniformity of application of a mold release agent using discrete crystal nuclei as claimed in claim 9 wherein the heating temperature is 43 ℃.

Technical Field

The invention relates to the technical field of discrete crystal nuclei and industrial coating, in particular to a method for improving the coating uniformity of a release agent by using the discrete crystal nuclei.

Background

The surface accuracy of the electroformed mould depends on the quality of the demoulding. Excessive bonding force between the core mold and the replica during demolding may cause damage to the mold surface. Therefore, a release agent is applied to the surface of the mandrel before electroforming. Potassium dichromate solution is a common release agent in industry for assisting electroforming release, and uneven distribution of solution during coating causes difficulty in releasing and local damage to the mold surface, and simultaneously damages the core mold. The main reason is that the surface of the high-precision metal core mold has poor hydrophilicity, so that the potassium dichromate solution is distributed on the surface of the core mold in the form of droplets, and only a local anti-adhesion effect is formed. For release agents that are difficult to disperse in aqueous solutions, kunming corp-seine scientific limited liability company and university of kunming corp utilize improved coating devices to increase the uniformity of mixing of the release agent with the aqueous solution in order to increase the release agent application uniformity (a device for uniformly applying the release agent, 201921244397.3). The electrochemical surface modification method is a common method for increasing wettability of an aqueous solution on a solid surface by changing oxygen-containing groups on the solid surface (wubo. organic electrolyte electrochemically modifies surface properties of PAN-based carbon fibers, 2016). The data show that the oxide of Cr has higher surface energy (Machilus thunbergii plasma spraying Cr₂O₃2016), which can increase the adhesion of liquid drops on the solid surface (Vechietti. flatness of coating alloy surface modification on the surface of the solid and the surface of the poor floor of the needle oil/hydraulic as coating, 2018), and is favorable for the liquid drops to wet the solid surface. The potassium dichromate is easy to dissolve in water, and in order to realize the coating uniformity of the potassium dichromate solution on the surface of the die, the invention utilizes an electrochemical method to deposit a layer of fine discrete heterogeneous crystal nucleus on the surface of a core die to form Cr₂O₃The surface energy of the core die can be increased, namely the hydrophilicity of the surface is increased, on the basis, the uniform coating of the potassium dichromate solution is realized, the service life of the core die can be prolonged, and the surface quality of the casting is greatly improved.

Disclosure of Invention

The invention aims to provide a method for improving the coating uniformity of a release agent by utilizing discrete crystal nuclei, which is used for improving the surface adhesion of a core mold by modifying the surface of the core mold in a mode of electrodepositing a layer of Cr metal discrete crystal nuclei on the surface of the core mold and further improving the coating uniformity of potassium dichromate.

The invention comprises the following steps:

1) preparing a release agent solution: adding deionized water into a beaker, adding potassium dichromate powder into the beaker, and stirring;

2) preparing an electroplating solution: chromium sulfate, ammonium chloride, boric acid and glycine are added into an electrodeposition tank, and then deionized water is added into the tank and stirred.

3) Electro-deposition of Cr discrete nuclei: fixing a copper sheet on a negative plate, connecting a power supply cathode, connecting a titanium basket as an anode, connecting a power supply anode, adjusting the current, adjusting the heating temperature, performing electrodeposition to obtain discrete crystal nuclei of Cr metal, and calculating the crystal nucleus density on the surface of a core mold according to a polarization curve.

In the step 1), the temperature of the deionized water can be 20-25 ℃; the addition amount of the potassium dichromate can be 5 to 10 percent of the weight of water; the mass-volume concentration of the potassium dichromate can be 50 g/L-100 g/L; the obtained solution can be kept stand for 1h at the temperature of 20-25 ℃.

In the step 2), the mass-volume concentration of the chromium sulfate can be 20g/L to 40g/L, the mass-volume concentration of the ammonium chloride can be 200g/L to 400g/L, the mass-volume concentration of the boric acid can be 60g/L to 100g/L, and the mass-volume concentration of the glycine can be 20g/L to 50 g/L; the temperature of the deionized water can be 20-25 ℃; the pH value of the obtained electroplating solution is 3.0-3.5; the obtained electroplating solution can be kept stand for 8-15 hours at the temperature of 20-25 ℃.

In the step 3), the current density may be 5 to 10A/dm²(ii) a The time of the electrodeposition can be 5-15 s; the heating temperature may be 40 to 50 ℃, preferably 43 ℃.

According to the invention, a layer of Cr discrete crystal nucleus is electrodeposited on the surface of copper to modify the surface, and the high surface energy of the Cr discrete crystal nucleus is utilized to increase the surface adhesion of the copper, so that the adhesion of a potassium dichromate solution on the surface of the copper is facilitated, the coating uniformity is increased, and more favorable conditions are provided for electroforming and demolding of a copper mold.

Compared with the prior art, the invention has the following outstanding technical effects:

1) the deposition parameters can be conveniently adjusted by using a power supply in production.

2) Suitable electroplating bath formulations are preferred.

3) The Cr crystal nucleus density can be controlled by adjusting parameters such as the electrodeposition time, the current density, the plating solution formula and the like, the coating time of the release agent is reduced, and the coating uniformity of the potassium dichromate solution is improved.

4) The discrete crystal nucleus prepared once can be used for multiple times.

5) The precise electroforming mold is simple to implement, mirror surface quality can be obtained after demolding, the roughness is below 10 nanometers, and the service life of the core mold and the quality of a copy mold are greatly improved.

Drawings

FIG. 1 is a schematic diagram of an experimental apparatus for electrodeposition of Cr discrete nuclei in example 1 of the present invention.

FIG. 2 is a view showing a core mold (copper sheet) used in example 1 of the present invention.

Fig. 3 is a graph showing the effect of the potassium dichromate release agent directly applied to the surface of the core mold in example 1 of the present invention.

FIG. 4 is a graph showing the effect of applying a potassium dichromate release agent after a layer of discrete Cr crystal nuclei is electrodeposited on the surface of the core mold in example 1 of the present invention.

Detailed Description

The following examples will further illustrate the present invention with reference to the accompanying drawings.

Example 1

Preparing an electroplating solution: respectively weighing 25g of chromium sulfate, 200g of ammonium chloride, 60g of boric acid and 25g of glycine, adding 1000mL of deionized water into a plating tank, fully stirring, heating the plating solution to 40 ℃, and keeping the temperature for 1 h.

Preparing a release agent solution: weighing 5g of potassium dichromate, adding 100mL of deionized water into a beaker at the temperature of 20 ℃, fully stirring, and standing for 1 h.

Pretreatment of the copper sheet: activating the copper sheet by acetic acid, degreasing by acetone, washing by deionized water after ultrasonic cleaning, and air-drying.

Electro-deposition of Cr discrete nuclei: referring to FIG. 1, the cleaned copper sheet is fixed on the cathode and connected to the power supply cathode, the anode is connected to the anode by titanium basket, and the current density is set at 5A/dm²Setting the deposition time to be 5s, turning on a power switch to carry out electrodeposition, taking out the cathode copper sheet after the deposition is finished, putting the cathode copper sheet into deionized water solution to remove residual plating solution on the surface, wherein the density of the discrete crystal nucleus of the deposited Cr is about 3.25 multiplied by 10⁶/cm²。

Coating with a potassium dichromate solution: firstly, directly coating the potassium dichromate solution on the surface of an untreated copper sheet shown in figure 2, standing for 5min, pouring the potassium dichromate solution on the surface of a copper mold, and observing the surface by using an optical microscope after the surface is dried, as shown in figure 3. Secondly, coating the potassium dichromate solution on the surface of the copper sheet with the electro-deposition Cr discrete crystal nucleus, standing for 15s, pouring the potassium dichromate solution on the surface of the copper mold, and observing the surface by using an optical microscope after the surface is dried, as shown in figure 4. It can be seen that the distribution of the potassium dichromate release agent directly coated on the surface of the copper sheet is very uneven, but the surface is completely covered after Cr discrete crystal nuclei are electrodeposited, so that the coating uniformity of the release agent is greatly improved.

Example 2

Preparing an electroplating solution: 30g of chromium sulfate, 300g of ammonium chloride, 70g of boric acid and 30g of glycine are respectively weighed, 1000mL of deionized water is added into a plating tank, the mixture is fully stirred, and the plating solution is heated to 43 ℃ and is kept warm for 1 h.

Preparing a release agent solution: weighing 8g of potassium dichromate, adding 100mL of deionized water into a beaker at the temperature of 22 ℃, fully stirring, and standing for 1 h.

Pretreatment of the copper sheet: activating the copper sheet by acetic acid, degreasing by acetone, washing by deionized water after ultrasonic cleaning, and air-drying.

Electro-deposition of Cr discrete nuclei: fixing the cleaned copper sheet on the cathode connected to the negative pole of a power supply, connecting the anode to the positive pole by using a titanium basket, and setting the current density to be 8A/dm²Setting the deposition time to 10s, turning on the power switchPerforming electrodeposition, taking out the cathode copper sheet after the electrodeposition is finished, and putting the cathode copper sheet into deionized water solution to remove residual plating solution on the surface, wherein the density of discrete crystal nuclei of the deposited Cr is about 7.26 multiplied by 10⁶/cm²。

Coating with a potassium dichromate solution: firstly, directly coating a potassium dichromate solution on the surface of an untreated copper sheet, standing for 8min, pouring the potassium dichromate solution on the surface of a copper mold, and observing the surface by using an optical microscope after the surface is dried. And secondly, coating the potassium dichromate solution on the surface of the copper sheet with the electro-deposition Cr discrete crystal nucleus, standing for 20s, pouring the potassium dichromate solution on the surface of the copper mold, and observing the surface by using an optical microscope after the surface is dried. It can be seen that the distribution of the potassium dichromate release agent directly coated on the surface of the copper sheet is very uneven, but the surface is completely covered after Cr discrete crystal nuclei are electrodeposited, so that the coating uniformity of the release agent is greatly improved.

Example 3

Preparing an electroplating solution: 30g of chromium sulfate, 200g of ammonium chloride, 80g of boric acid and 30g of glycine are respectively weighed, 1000mL of deionized water is added into a plating tank, the mixture is fully stirred, and the plating solution is heated to 45 ℃ and is kept warm for 1 h.

Preparing a release agent solution: weighing 10g of potassium dichromate, adding 100mL of deionized water into a beaker at the temperature of 25 ℃, fully stirring, and standing for 1 h.

Pretreatment of the copper sheet: activating the copper sheet by acetic acid, degreasing by acetone, washing by deionized water after ultrasonic cleaning, and air-drying.

Electro-deposition of Cr discrete nuclei: fixing the cleaned copper sheet on the cathode connected to the negative pole of a power supply, connecting the anode to the positive pole by using a titanium basket, and setting the current density to be 10A/dm²Setting the deposition time to 15s, turning on a power switch to carry out electrodeposition, taking out the cathode copper sheet after the deposition is finished, putting the cathode copper sheet into deionized water solution to remove residual plating solution on the surface, wherein the density of discrete crystal nuclei of the deposited Cr is about 1.29 multiplied by 10⁷/cm²。

Coating with a potassium dichromate solution: firstly, directly coating a potassium dichromate solution on the surface of an untreated copper sheet, standing for 10min, pouring the potassium dichromate solution on the surface of a copper mold, and observing the surface by using an optical microscope after the surface is dried. And secondly, coating the potassium dichromate solution on the surface of the copper sheet with the electro-deposition Cr discrete crystal nucleus, standing for 25s, pouring the potassium dichromate solution on the surface of the copper mold, and observing the surface by using an optical microscope after the surface is dried. It can be seen that the distribution of the potassium dichromate release agent directly coated on the surface of the copper sheet is very uneven, but the surface is completely covered after the Cr crystal nucleus thin layer is electrodeposited, and the release agent coating uniformity is greatly improved.

The above-described embodiments are merely preferred embodiments of the present invention, and should not be construed as limiting the scope of the invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention.