阅读说明：本技术 涂覆阴极的组合物及制备方法、用途和钨阴极的制备方法 (Composition for coating cathode, preparation method and application thereof, and preparation method of tungsten cathode ) 是由 张鸣一 高平 王昊 于 2021-09-29 设计创作，主要内容包括：本发明公开了一种涂覆阴极的组合物,以重量份数计,包括如下成分：55～70份3Al-(2)O-(3)·2SiO-(2)、3～10份水玻璃、1～6份树脂和0.5～5份有机膨润土。该涂覆阴极的组合物可用于提高待涂覆材料的耐侵蚀性。此外,本发明还公开了一种钨阴极的制备方法,包括如下步骤：(1)在钨基体的待涂覆部位表面涂覆水玻璃,形成打底层；(2)在所述打底层上涂覆所述涂覆阴极的组合物,烘干,形成耐侵蚀层。采用该制备方法制成的钨阴极,其使用寿命在265天以上。(The invention discloses a cathode coating composition, which comprises the following components in parts by weight: 55-70 parts of 3Al 2 O 3 ·2SiO 2 3-10 parts of water glass, 1-6 parts of resin and 0.5-5 parts of organic bentonite. The cathode-coating composition can be used to improve the erosion resistance of the material to be coated. In addition, the invention also discloses a preparation method of the tungsten cathode, which comprises the following steps: (1) coating water glass on the surface of a part to be coated of the tungsten substrate to form a priming layer; (2) and coating the composition for coating the cathode on the priming layer, and drying to form an erosion-resistant layer. The tungsten cathode prepared by the preparation method has the service life of more than 265 days.)

1. The cathode coating composition is characterized by comprising the following components in parts by weight: 55-70 parts of 3Al₂O₃·2SiO₂3-10 parts of water glass, 1-6 parts of resin and 0.5-5 parts of organic bentonite.

2. The cathode-coating composition of claim 1, comprising, in parts by weight: 60-70 parts of 3Al₂O₃·2SiO₂5-8 parts of water glass, 2-5 parts of resin, 1-5 parts of organic bentonite, 13-30 parts of water, 0.05-0.8 part of alkylphenol polyoxyethylene and 0.01-1 part of fatty alcohol with 1-4 carbon atoms.

3. The cathode-coating composition of claim 2, consisting of: 3Al₂O₃·2SiO₂60 to 70 weight percent of water glass, 5 to 8 weight percent of water glass, 2 to 5 weight percent of resin, 1 to 5 weight percent of organic bentonite, 13 to 30 weight percent of water, 100.1 to 0.5 weight percent of OP-100, 0.01 to 0.5 weight percent of n-butyl alcohol and 0.1 to 3 weight percent of preservative;

the sum of the weight percentages of the components is 100 wt%.

4. A method of preparing a cathode-coating composition according to any one of claims 1 to 3, comprising the steps of:

1) adding 3Al₂O₃·2SiO₂Mixing with organic bentonite to obtain a premix;

2) raw materials including water glass and resin were added to the premix and mixing was continued to obtain a cathode-coated composition.

5. The method according to claim 4, wherein the 3Al is₂O₃·2SiO₂The granularity of the particles is 150-300 meshes; the particle size of the organic bentonite is 140-200 meshes;

step 1) and step 2) are carried out in a ball mill, wherein,

in the step 1), the rotation speed of ball milling is 250-600 rpm, the revolution speed is 150-400 rpm, and the ball milling time is 4-8 h;

in the step 2), the rotation speed of the ball mill is 250-600 rpm, the revolution speed is 150-400 rpm, and the ball milling time is 5-10 h.

6. Use of a cathode-coating composition according to any one of claims 1 to 3 for increasing the erosion resistance of a material to be coated.

7. The preparation method of the tungsten cathode is characterized by comprising the following steps:

(1) coating water glass on the surface of a part to be coated of the tungsten substrate to form a priming layer;

(2) and coating the composition for coating the cathode on the priming layer, and drying to form an erosion-resistant layer.

8. The method for preparing the tungsten cathode according to claim 7, wherein the thickness of the primer layer is 0.3 to 1 mm; 1-6 layers of erosion resistant layers are coated, and the thickness of each layer of erosion resistant layer is 0.5-2 mm; the drying temperature is 80-150 ℃, and the drying time is 4-10 h.

9. The method for preparing a tungsten cathode according to claim 8, wherein, before the step (1), a part to be coated of the tungsten substrate is threaded;

and (3) filling surface pores and pits of the erosion-resistant layer after the step (2) is carried out.

10. The method for preparing a tungsten cathode according to claim 9, wherein the portion to be coated is a region from the same end of the tungsten substrate between 1/10 of the length of the tungsten substrate and 1/4 of the length of the tungsten substrate; the service life of the tungsten cathode is more than 265 days.

Technical Field

The invention relates to a cathode coating composition, a preparation method and application thereof, and a preparation method of a tungsten cathode.

Background

In the process of preparing rare earth metal by adopting a rare earth molten salt electrolysis method, refractory and corrosion-resistant metal is required to be used as a cathode. Currently, tungsten cathodes are mostly adopted in production. Because the working condition of the tungsten cathode is very bad, the tungsten cathode part exposed above the molten salt liquid level, particularly the part close to the molten salt liquid level has the highest temperature, and the oxidation action is very strong under the action of the furnace mouth airflow, so that the part is very easy to corrode, and the service life of the tungsten cathode is seriously influenced.

CN203174212U discloses a tungsten cathode having a body and one or two protrusions provided on the body, the protrusions having a cross-sectional area larger than the cross-sectional area of the body. The utility model discloses a through the cross-sectional area extension tungsten cathode's of the perishable position of increase tungsten cathode life, it does not improve the erosion resistance performance of tungsten cathode by nature, and tungsten belongs to rare metal, and is expensive, and the cost of this method is higher. Furthermore, the method is only suitable for producing new tungsten cathodes, and is not suitable for tungsten cathodes that have already been used.

Disclosure of Invention

In view of the above, an object of the present invention is to provide a cathode-coating composition, which can be used to prolong the service life of a tungsten cathode, and has low cost and wide application range.

It is another object of the present invention to provide a method for preparing a cathode-coating composition, which is simple in process and can produce a cathode-coating composition that improves erosion resistance of the cathode.

It is a further object of the present invention to provide the use of a composition for coating a cathode to improve the erosion resistance of the material to be coated.

Still another object of the present invention is to provide a method for preparing a tungsten cathode, which can improve the high temperature resistance and erosion resistance of the tungsten cathode and prolong the service life of the tungsten cathode.

In one aspect, the invention provides a composition for coating a cathode, which comprises the following components in parts by weight: 55-70 parts of 3Al₂O₃·2SiO₂3-10 parts of water glass, 1-6 parts of resin and 0.5-5 parts of organic bentonite.

In certain embodiments, the cathode-coating composition consists of, by weight parts, a composition such asThe following components: 55-70 parts of 3Al₂O₃·2SiO₂3-10 parts of water glass, 1-6 parts of resin, 0.5-5 parts of organic bentonite and 13-30 parts of water. In other embodiments, the cathode-coating composition consists of, in parts by weight: 55-70 parts of 3Al₂O₃·2SiO₂3-10 parts of water glass, 1-6 parts of resin, 0.5-5 parts of organic bentonite and 13-30 parts of water, and functional additives for improving the dispersibility, permeability and wettability of the composition, such as alkylphenol ethoxylates and fatty alcohol. According to some embodiments of the invention, the composition coating the cathode may further comprise a preservative for extending the shelf life of the composition.

The cathode-coating composition according to the invention preferably comprises the following components in parts by weight: 60-70 parts of 3Al₂O₃·2SiO₂5-8 parts of water glass, 2-5 parts of resin, 1-5 parts of organic bentonite, 13-30 parts of water, 0.05-0.8 part of alkylphenol polyoxyethylene and 0.01-1 part of fatty alcohol with 1-4 carbon atoms.

In the present invention, 3Al₂O₃·2SiO₂Is a support material used in the composition to support the erosion resistant layer. Adding 3Al₂O₃·2SiO₂As a supporting material, the corrosion resistance of the corrosion-resistant layer to hydrofluoric acid and hydrofluoric acid gas can be improved, and the high-temperature stability of the corrosion-resistant layer can be ensured.

In the present invention, the resin may be selected from water-soluble resins such as urea-formaldehyde resin, melamine-formaldehyde resin, acrylic resin, preferably acrylic resin. The invention adds the water glass and the resin as the adhesive at the same time, wherein the water glass can form SiO on the surface of the metal after contacting the metal₂A gel film to protect the metal from acid corrosion; the resin can play a super strong adhesion role on the metal and improve the corrosion resistance of the metal; the two have synergistic effect to ensure the adhesion and erosion resistance of the erosion resistant layer.

In the invention, the organic bentonite can not only improve the stability and film forming property of the composition, but also improve the erosion resistance of the erosion resistant layer.

In the present invention, the water may be selected from one or more of deionized water, ultrapure water, double distilled water, purified water, and distilled water, and preferably purified water.

In the invention, the alkylphenol polyoxyethylene ether can be one or more selected from nonylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether and dinonylphenol polyoxyethylene ether; preferably octyl phenol polyoxyethylene ether; more preferably octyl phenol polyoxyethylene ether OP-10.

In the present invention, the aliphatic alcohol having 1 to 4 carbon atoms may be selected from ethanol, n-propanol, isopropanol or n-butanol, and preferably n-butanol.

The cathode-coating composition according to the invention preferably consists of: 3Al₂O₃·2SiO₂60 to 70 weight percent of water glass, 5 to 8 weight percent of water glass, 2 to 5 weight percent of resin, 1 to 5 weight percent of organic bentonite, 13 to 30 weight percent of water, 100.1 to 0.5 weight percent of OP-100, 0.01 to 0.5 weight percent of n-butyl alcohol and 0.1 to 3 weight percent of preservative; the sum of the weight percentages of the components is 100 wt%. The composition for coating the cathode in the proportion has good stability and good bonding and film forming effects. According to some embodiments of the invention, the erosion resistance of the tungsten cathode can be improved by coating the tungsten cathode with the cathode-coating composition according to the proportion, the service life of the tungsten cathode is prolonged from about 200 days to 260-300 days, and the service life is prolonged by 30-50%.

In the present invention, the preservative may be a conventional preservative, for example, a benzoic acid and a salt thereof, an isothiazolinone preservative, etc., and is preferably a preservative used for paints, for example, a paint solvent preservative of the jinan yuan feiwei chemical limited.

In another aspect, the present invention provides a method for preparing the above composition for coating a cathode, comprising the steps of:

1) adding 3Al₂O₃·2SiO₂Mixing with organic bentonite to obtain a premix;

2) raw materials including water glass and resin were added to the premix and mixing was continued to obtain a cathode-coated composition.

According to the preparation method of the present invention, preferably, the 3Al₂O₃·2SiO₂The granularity of the particles is 150-300 meshes; the particle size of the organic bentonite is 140-200 meshes;

the step 1) and the step 2) are carried out in a ball mill, wherein in the step 1), the rotation speed of the ball mill is 250-600 rpm, the revolution speed is 150-400 rpm, and the ball milling time is 4-8 h; in the step 2), the rotation speed of the ball mill is 250-600 rpm, the revolution speed is 150-400 rpm, and the ball milling time is 5-10 h.

According to some embodiments of the invention, 3Al₂O₃·2SiO₂The granularity of the particles is 200-300 meshes; the particle size of the organic bentonite is 180-200 meshes. Therefore, a good dispersing effect can be ensured, and a better supporting effect can be achieved.

According to other embodiments of the present invention, in step 1), the rotation speed of the ball mill is 350 to 500rpm, the revolution speed is 200 to 350rpm, and the ball milling time is 6 to 7 hours; in the step 2), the rotation speed of ball milling is 350-500 rpm, the revolution speed is 200-350 rpm, and the ball milling time is 6-8 h. 3Al can be reacted by step 1)₂O₃·2SiO₂The organic bentonite is effectively mixed, and the composition prepared under the condition parameters has higher viscosity and thixotropy; the composition prepared under the parameter condition of the step 2) has no bubbles or particles, and has optimal stability and film forming effect.

In a further aspect, the present invention provides the use of a composition for coating a cathode as described above to improve the erosion resistance of the material to be coated. The material to be coated may be any metallic material, such as a cathode for molten salt electrolysis. According to some embodiments of the invention, the material to be coated is a tungsten cathode.

In another aspect, the present invention provides a method for preparing a tungsten cathode, comprising the steps of:

(1) coating water glass on the surface of a part to be coated of the tungsten substrate to form a priming layer;

(2) and coating the composition for coating the cathode on the priming layer, and drying to form an erosion-resistant layer.

According to the preparation method of the tungsten cathode, the thickness of the bottom layer is preferably 0.3-1 mm; 1-6 layers of erosion resistant layers are coated, and the thickness of each layer of erosion resistant layer is 0.5-2 mm; the drying temperature is 80-150 ℃, and the drying time is 4-10 h.

According to some embodiments of the invention, the primer layer has a thickness of 0.3 to 0.6 mm; 2-3 layers of erosion resistant layers are coated, and the thickness of each layer of erosion resistant layer is 1-1.3 mm; the drying temperature is 80-150 ℃, and the drying time is 5-8 h. Therefore, the better adhesion effect of the erosion resistant layer can be ensured, and the erosion resistance can be ensured.

According to the preparation method of the tungsten cathode of the present invention, preferably, before the step (1) is performed, the part of the tungsten substrate to be coated is threaded; and (3) filling surface pores and pits of the erosion-resistant layer after the step (2) is carried out.

In the invention, the thread processing is firstly carried out on the part to be coated, so that the contact area between the tungsten matrix and the erosion-resistant layer can be increased, the adhesive force is enhanced, and the bonding effect is enhanced.

In the present invention, the material filling the surface pores and pits may be selected from the composition of the present invention or refractory mortar, preferably refractory mortar.

According to the preparation method of the tungsten cathode, the part to be coated is preferably a region from 1/10 of the length of the tungsten matrix to 1/4 of the length of the tungsten matrix from the same end of the tungsten matrix; the service life of the tungsten cathode is more than 265 days.

As shown in fig. 1, the coated region of the present invention includes a middle region 1 and end regions 2; wherein the thickness of each coating layer of the end region 2 gradually increases from the end to the middle of the coating region; the thickness of each coating layer of the middle region 1 is equal to the maximum thickness of each coating layer of the end regions 2. Therefore, the internal stress generated by the tungsten cathode in the using process can be reduced, and the coating layer is prevented from cracking or falling off. In the present invention, the thickness of the primer layer and the thickness of the erosion resistant layer both refer to the thickness of the coating layer in the central region 1.

The cathode-coating composition of the present invention is supplemented with 3Al₂O₃·2SiO₂The water glass, the resin and the organic bentonite are cooperatively matched, so that the composition has good film forming property, high temperature resistance stability and erosion resistance. In addition, the composition has low cost, can be used for repairing corroded cathodes, and has a wide application range. The preparation method of the tungsten cathode has simple process, and the tungsten cathode prepared by the method has the service life prolonged from about 200 days (the service life of a pure tungsten cathode) to 260-300 days, and the service life is prolonged by 30-50%.

Drawings

Fig. 1 is a longitudinal sectional view of a tungsten cathode of the present invention.

The reference numbers are as follows: 1-a middle region; 2-end region.

Detailed Description

The present invention will be further described with reference to specific embodiments, but the scope of the present invention is not limited thereto.

The starting materials and test methods used in the examples and comparative examples are as follows:

(1) water-soluble resin: acrylic resin;

(2) preservative: the coating solvent preservative purchased from Jinan Yuan Feiwei chemical Co., Ltd is a mixed solution consisting of thymol, sodium pentachlorophenate, pentachlorophenol, benzoic acid and industrial formaldehyde;

(3) testing conditions of the service life of the tungsten cathode are as follows: the electrolyte is mixed molten salt of rare earth fluoride and lithium fluoride, the electrolysis temperature is 1100 ℃, and the electrolysis current is 8000A.

Preparation example 1

1) 65 parts by weight of 3Al₂O₃·2SiO₂Putting (granularity is 200 meshes) and 3 parts by weight of organic bentonite (granularity is 200 meshes) into a ball milling tank, and placing the ball milling tank into a planetary ball mill for mixing to obtain a premix;

wherein the rotation speed of the ball mill is 400rpm, the revolution speed is 300rpm, and the ball milling time is 6 h.

2) Adding 6 parts by weight of water glass, 4 parts by weight of water-soluble resin, 0.3 part by weight of OP-10, 0.02 part by weight of n-butanol, 21 parts by weight of purified water and 0.68 part by weight of preservative to the premix, placing in a planetary ball mill and continuing mixing to obtain a cathode-coated composition;

wherein the rotation speed of the ball mill is 400rpm, the revolution speed is 300rpm, and the ball milling time is 7 h.

Preparation example 2

1) 70 parts by weight of 3Al₂O₃·2SiO₂Putting (granularity is 200 meshes) and 3 parts by weight of organic bentonite (granularity is 200 meshes) into a ball milling tank, and placing the ball milling tank into a planetary ball mill for mixing to obtain a premix;

wherein the rotation speed of the ball mill is 400rpm, the revolution speed is 300rpm, and the ball milling time is 6.5 h.

2) Adding 8 parts by weight of water glass, 4 parts by weight of water-soluble resin, 0.3 part by weight of OP-10, 0.02 part by weight of n-butanol, 14 parts by weight of purified water and 0.68 part by weight of preservative to the premix, placing in a planetary ball mill and continuing mixing to obtain a cathode-coated composition;

wherein the rotation speed of the ball mill is 400rpm, the revolution speed is 300rpm, and the ball milling time is 7 h.

Preparation example 3

1) 66 parts by weight of 3Al₂O₃·2SiO₂Placing (granularity is 300 meshes) and 3 parts by weight of organic bentonite (granularity is 200 meshes) into a ball milling tank, and placing the ball milling tank into a planetary ball mill for mixing to obtain a premix;

wherein the rotation speed of the ball mill is 400rpm, the revolution speed is 300rpm, and the ball milling time is 6 h.

2) Adding 5 parts by weight of water glass, 2 parts by weight of water-soluble resin, 0.3 part by weight of OP-10 emulsifier, 0.02 part by weight of n-butanol and 22 parts by weight of purified water, 1.68 parts by weight of preservative to the premix, placing the premix in a planetary ball mill, and continuing mixing to obtain a cathode-coated composition;

wherein the rotation speed of the ball mill is 400rpm, the revolution speed is 300rpm, and the ball milling time is 6 h.

Comparative preparation example 1

1) 50 parts by weight of 3Al₂O₃·2SiO₂Putting (granularity is 200 meshes) and 3 parts by weight of organic bentonite (granularity is 200 meshes) into a ball milling tank, and placing the ball milling tank into a planetary ball mill for mixing to obtain a premix;

wherein the rotation speed of the ball mill is 400rpm, the revolution speed is 300rpm, and the ball milling time is 6 h.

2) Adding 4 parts by weight of water glass, 3 parts by weight of water-soluble resin, 0.3 part by weight of OP-10 emulsifier, 0.02 part by weight of n-butanol and 39 parts by weight of purified water, 0.68 part by weight of preservative to the premix, placing the premix in a planetary ball mill, and continuing mixing to obtain a cathode-coated composition;

wherein the rotation speed of the ball mill is 400rpm, the revolution speed is 300rpm, and the ball milling time is 7 h.

Example 1

(1) Taking a tungsten rod with the diameter of 80mm and the length of 1000mm, performing thread machining on a part to be coated of the tungsten rod, wherein the part to be coated is specifically positioned at a position 120-250 mm away from the end of the tungsten rod (namely, the part 120mm below the end of the tungsten rod starts to perform downward thread machining, and the thread machining length is 130mm), and coating water glass with the thickness of 0.5mm on the surface of the thread to form a bottom layer;

(2) coating the composition coated with the cathode prepared in preparation example 1 on the priming layer, and then placing the priming layer in a high-temperature oven for drying to form a first erosion-resistant layer;

after the first erosion-resistant layer is completely dried, continuously coating the composition coated with the cathode prepared in the preparation example 1, and then placing the composition in a high-temperature oven for drying to form a second erosion-resistant layer;

after the second erosion-resistant layer is completely dried, continuously coating the composition coated with the cathode prepared in the preparation example 1, and then placing the composition in a high-temperature oven for drying to form a third erosion-resistant layer;

wherein the drying temperature is 100 ℃, and the drying time is 6 h; the thickness of each erosion resistant layer is 1 mm;

(3) and (4) comprehensively inspecting the surface of the erosion-resistant layer, and filling defects such as air holes, pits and the like with refractory clay to obtain the tungsten cathode.

The service life of the tungsten cathode is tested, and the test result shows that the service cycle of the tungsten cathode is 266 days.

Example 2

(1) Taking a tungsten rod with the diameter of 80mm and the length of 1000mm, carrying out thread machining on a part to be coated of the tungsten rod, wherein the part to be coated is specifically positioned at a position 120-250 mm away from the end of the tungsten rod, and coating water glass with the thickness of 0.6mm on the surface of the thread to form a bottom coating layer;

(2) coating the composition coated with the cathode prepared in preparation example 2 on the priming layer, and then placing the priming layer in a high-temperature oven for drying to form a first erosion-resistant layer;

after the first erosion-resistant layer is completely dried, continuously coating the composition coated with the cathode prepared in the preparation example 2, and then placing the composition in a high-temperature oven for drying to form a second erosion-resistant layer;

after the second erosion-resistant layer is completely dried, continuously coating the composition coated with the cathode prepared in the preparation example 2, and then placing the composition in a high-temperature oven for drying to form a third erosion-resistant layer;

wherein the drying temperature is 110 ℃, and the drying time is 7 h; the thickness of each erosion resistant layer is 1.2 mm;

(3) and (4) comprehensively inspecting the surface of the erosion-resistant layer, and filling defects such as air holes, pits and the like with refractory clay to obtain the tungsten cathode.

The service life of the tungsten cathode is tested, and the test result shows that the service cycle of the tungsten cathode is 270 days.

Example 3

(1) Taking a tungsten rod with the diameter of 80mm and the length of 1000mm, carrying out thread machining on a part to be coated of the tungsten rod, wherein the part to be coated is specifically positioned at a position 120-250 mm away from the end of the tungsten rod, and coating water glass with the thickness of 0.5mm on the surface of the thread to form a bottom coating layer;

(2) coating the composition coated with the cathode prepared in preparation example 3 on the priming layer, and then placing the priming layer in a high-temperature oven for drying to form a first erosion-resistant layer;

after the first erosion-resistant layer is completely dried, continuously coating the composition coated with the cathode prepared in the preparation example 3, and then placing the composition in a high-temperature oven for drying to form a second erosion-resistant layer;

after the second erosion-resistant layer is completely dried, continuously coating the composition coated with the cathode prepared in the preparation example 3, and then placing the composition in a high-temperature oven for drying to form a third erosion-resistant layer;

wherein the drying temperature is 110 ℃, and the drying time is 6 h; the thickness of each erosion resistant layer is 1.3 mm;

(3) and (4) comprehensively inspecting the surface of the erosion-resistant layer, and filling defects such as air holes, pits and the like with refractory clay to obtain the tungsten cathode.

The service life of the tungsten cathode is tested, and the test result shows that the service cycle of the tungsten cathode is 300 days.

Comparative example 1

The procedure was as in example 1 except for the following steps:

the cathode-coating composition prepared in comparative preparation example 1 was selected for coating.

The tungsten cathode was tested for service life and it was found during the test that 3Al was present in the cathode-coated composition of comparative preparation example 1₂O₃·2SiO₂The dosage of the composition is too small, so that the composition is difficult to form an erosion resistant layer, and the formed erosion resistant layer has poor high temperature stability, so that the coating layer falls off in the middle and later periods of the test. The test results show that the service life of the tungsten cathode is 209 days.

Comparative example 2

The procedure was as in example 1 except for the following steps:

the surface of the thread is not coated with water glass.

The service life of the tungsten cathode is tested, and the test result shows that the service cycle of the tungsten cathode is 211 days.

Comparative example 3

The tungsten rod with the diameter of 80mm and the length of 1000mm is used as a tungsten cathode, the service life of the tungsten cathode is tested, and the test result shows that the service cycle of the tungsten cathode is 201 days.

The test results of examples 1-3 and comparative examples 1-3 show that the composition for coating the cathode provided by the invention can better form an erosion-resistant layer with good stability, and is beneficial to prolonging the service life of the tungsten cathode. The preparation method can prolong the service life of the pure tungsten cathode from about 200 days to 260-300 days by 30-50%.

The present invention is not limited to the above-described embodiments, and any variations, modifications, and substitutions which may occur to those skilled in the art may be made without departing from the spirit of the invention.