CN111172555B

CN111172555B - Carbon anode plate for fluorine production

Info

Publication number: CN111172555B
Application number: CN202010075403.8A
Authority: CN
Inventors: 刘坤; 杭颂
Original assignee: EIGHTH RESEARCH INSTITUTE OF NUCLEAR TECHNOLOGY
Current assignee: EIGHTH RESEARCH INSTITUTE OF NUCLEAR TECHNOLOGY
Priority date: 2020-01-22
Filing date: 2020-01-22
Publication date: 2022-11-08
Anticipated expiration: 2040-01-22
Also published as: CN111172555A

Abstract

The invention relates to a carbon anode plate for preparing fluorine, which consists of a carbon plate and a carbon/silicon carbide doped coating deposited on the surface of the carbon plate. Compared with the prior art, the invention adopts a special treatment process to form the protective layer on the surface of the carbon anode plate, can improve the surface corrosion resistance, delays the formation of the passivation layer on the surface layer of the carbon anode and is beneficial to prolonging the service life of the carbon anode.

Description

Carbon anode plate for fluorine production

Technical Field

The invention belongs to the technical field of carbon anode plates, and relates to a carbon anode plate for fluorine production.

Background

The elementary fluorine gas plays an important role in the nuclear industry and the integrated circuit industry, the intermediate temperature electrolysis fluorine preparation process is the only elementary fluorine gas preparation process for realizing the industrial production at present, and the process mainly takes an amorphous carbon material as an anode material.

The carbon anode is installed in the electrolytic cell in a clamping plate type and a screw type mode, wherein the screw type is mainly used for a 10KA electrolytic cell, at present, the service life of the domestic screw type carbon anode plate for installation is generally short, the stable operation life of most products under the working condition of 6-8 KA cannot reach 6 months, and the carbon anode becomes a bottleneck for restricting the development of the domestic fluorine preparation technology by electrolysis.

The main reasons for the failure of the carbon anode plate to operate continuously are cracking, and the cracking causes are many, and the carbon anode plate is typically corroded and polarized, so that the solution of the above problems can help to prolong the operating life of the carbon anode plate.

Disclosure of Invention

The invention aims to provide a carbon anode plate for fluorine preparation, which aims to overcome the defects in the prior art. The special treatment process is adopted to form the protective layer on the surface of the carbon anode plate, so that the surface corrosion resistance can be improved, the formation of a passivation layer on the surface layer of the carbon anode can be delayed, and the service life of the carbon anode can be prolonged.

The purpose of the invention can be realized by the following technical scheme:

a carbon anode plate for preparing fluorine consists of a carbon plate and a carbon/silicon carbide doped coating deposited on the surface of the carbon plate.

Further, in the carbon/silicon carbide doped coating, the content of silicon carbide in the coating is not more than 90%.

Furthermore, the thickness of the carbon/silicon carbide doped coating is not more than 10 μm.

Further, the carbon/silicon carbide doped coating is deposited by the following method:

placing the carbon plate in a vapor deposition furnace, and introducing CH ₄ 、SiCl ₄ 、H ₂ And N ₂ And (4) forming mixed gas, and depositing at high temperature to finish the process.

Further, in the mixed gas, CH ₄ 、SiCl ₄ 、H ₂ And N ₂ Are respectively 30%, 5% and 60%.

Furthermore, the flow rate of the mixed gas introduced into the vapor deposition furnace is 200L/h.

Furthermore, the process conditions of the high-temperature deposition are as follows: the pressure in the furnace was maintained at 10KPa, and the precipitate was deposited at 1200 ℃ for 30 hours.

The invention has the innovation that the silicon carbide is doped in the same conventional carbon coating, so that the hydrofluoric acid corrosion resistance of the product is improved, and meanwhile, the formation of a continuous graphite fluoride passivation layer is prevented due to the existence of the silicon carbide coating. In the component ratio, siCl ₄ And H ₂ The ratio of (b) should be properly controlled and should be maintained at a low level because, when the contents of the above two gases are too high, the formation of the silicon carbide coating is facilitated, and the formation of the carbon coating is not utilized, but the electrical conductivity of the silicon carbide is significantly inferior to that of carbon, so that when the content of the silicon carbide is too high, the electrical conductivity of the product is significantly reduced, and the adverse effect is generated.

Furthermore, before deposition, the carbon plate is subjected to surface polishing, ultrasonic cleaning and drying.

Compared with the prior art, the invention has the following advantages:

(1) The carbon/silicon carbide coating has better corrosion resistance than pure amorphous carbon;

(2) The continuous graphite fluoride passivation layer is more difficult to form, and the polarization resistance is better.

Detailed Description

The present invention will be described in detail with reference to specific examples. The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.

In the following examples, unless otherwise specified, all the materials or treatment techniques are conventional commercial products or conventional treatment techniques in the art.

Example 1:

taking the density of 1.75g/cm ³ The carbon plate with the graphitization degree of 0 and the size of 600mm, 300mm and 70mm is dried after surface polishing and ultrasonic cleaning, the dried carbon plate is placed in a vapor deposition furnace, and the volume ratio is as follows: 30% of CH ₄ 、5％SiCl ₄ 、5％H ₂ And 60% of N ₂ The mixed gas of (2) was introduced into a deposition furnace at a flow rate of 200L/h while maintaining a gas pressure in the furnace at 10KPa, and was deposited at 1200 ℃ for 30 hours. The coating thickness was tested to be about 4-5 μm.

Comparative example 1:

taking the density of 1.75g/cm ³ A carbon plate with graphitization degree of 0 and size of 600mm x 300mm x 70mm, the carbon plate is dried after surface polishing and ultrasonic cleaning, the dried carbon plate is placed in a vapor deposition furnace, and N is filled in the vapor deposition furnace ₂ As a protective atmosphere, N ₂ The mixture was introduced into a deposition furnace at a flow rate of 200L/h while maintaining the gas pressure in the furnace at 10KPa, and treated at 1200 ℃ for 30 hours.

The carbon anode plates in the comparative example 1 and the embodiment 1 are simultaneously placed in the same electrolytic tank to operate, the carbon anode plates are operated for 1 month under the working condition of 660A, taken out and soaked in KOH aqueous solution with the pH value of 11 and the temperature of 100 ℃ for a week, taken out and washed clean by pure water and then quickly dried, 4 samples with the diameter of 10mm and the thickness of 3mm are respectively prepared at the same positions of the surface, and XPS tests show that the content of unfluorinated carbon atoms in the example 1 is 50 percent and the content of unfluorinated carbon atoms in the comparative example 1 is 23.3 percent, and the test results show that the coating in the example 1 effectively prevents the formation of a fluorinated graphite layer and is beneficial to improving the corrosion resistance and the polarization resistance of the product.

In the above examples, the obtained carbon plate is preferably produced with an aggregate having a particle size of less than 20 μm. The concrete sources of the adopted aggregate are as follows: firstly, 300-mesh coke powder (namely petroleum coke powder) is purchased, and is reprocessed by using a superfine vertical mill grinding machine, and the final aggregate is obtained by screening through a 800-mesh standard sieve.

The embodiments described above are intended to facilitate a person of ordinary skill in the art in understanding and using the invention. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make modifications and alterations without departing from the scope of the present invention.

Claims

1. A carbon anode plate for fluorine production is characterized by consisting of a carbon plate and a carbon/silicon carbide doped coating deposited on the surface of the carbon plate;

in the carbon/silicon carbide doped coating, the silicon carbide content is not more than 90%;

the thickness of the carbon/silicon carbide doped coating is not more than 10 mu m;

the carbon/silicon carbide doped coating is obtained by deposition through the following method:

placing the carbon plate in a vapor deposition furnace, and introducing CH ₄ 、SiCl ₄ 、H ₂ And N ₂ The formed mixed gas is deposited at high temperature, and then the process is finished;

in a mixed gas of CH ₄ 、SiCl ₄ 、H ₂ And N ₂ The volume contents of (A) are respectively 30%, 5% and 60%;

the flow rate of the mixed gas introduced into the vapor deposition furnace is 200L/h;

the process conditions of high-temperature deposition are as follows: the pressure in the furnace was maintained at 10KPa, and the precipitate was deposited at 1200 ℃ for 30 hours.

2. The carbon anode plate for fluorine production according to claim 1, wherein the carbon plate is subjected to surface polishing, ultrasonic cleaning and drying before deposition.