CN113735605B

CN113735605B - Ultrahigh-power graphite electrode and preparation method thereof

Info

Publication number: CN113735605B
Application number: CN202111185463.6A
Authority: CN
Inventors: 占庆怀; 汪锡华
Original assignee: Shanghai Renpeng Industrial Co ltd
Current assignee: Shanghai Renpeng Industrial Co ltd
Priority date: 2021-10-12
Filing date: 2021-10-12
Publication date: 2022-10-11
Anticipated expiration: 2041-10-12
Also published as: CN113735605A

Abstract

The invention discloses an ultrahigh-power graphite electrode and a preparation method thereof, wherein needle coke, ultrahigh-power graphite electrode roasting fragments, ultrahigh-power graphite electrode graphite fragments, carbon fibers, silicon dioxide, rare earth materials, modified coal pitch and other components are compounded to improve the oxidation resistance and mechanical property of the graphite electrode, prolong the service life of the electrode and ensure the comprehensive performance of the graphite electrode. The invention discloses an ultrahigh-power graphite electrode and a preparation method thereof, the process design is reasonable, the component proportion is proper, the prepared graphite electrode has excellent thermal oxidation resistance and crack resistance, the mechanical property is excellent, the resistivity is reduced, the electrical property is excellent, and the practicability is higher.

Description

Ultrahigh-power graphite electrode and preparation method thereof

Technical Field

The invention relates to the technical field of graphite electrodes, in particular to an ultrahigh-power graphite electrode and a preparation method thereof.

Background

The graphite electrode is a high-temperature resistant graphite conductive material which is prepared by using petroleum coke and pitch coke as aggregates and coal pitch as an adhesive through the steps of raw material calcination, crushing and grinding, blending, kneading, molding, roasting, impregnation, graphitization and machining, is called as an artificial graphite electrode (referred to as a graphite electrode for short), and can be divided into a common power graphite electrode, a high-power graphite electrode and an ultrahigh-power graphite electrode according to the high and low mass indexes.

With the development of iron and steel enterprises, electric arc furnaces with larger capacity and higher current and voltage are widely used, so that higher requirements are put forward on the performance of graphite electrodes, the processing technology of the graphite electrodes on the market is complex, and the mechanical property and the electrical property can not meet the requirements of people.

Based on the above situation, we disclose an ultra-high power graphite electrode and a preparation method thereof, so as to solve the technical problem.

Disclosure of Invention

The present invention is directed to an ultra-high power graphite electrode and a method for manufacturing the same, which solves the above problems in the prior art.

In order to solve the technical problems, the invention provides the following technical scheme:

a preparation method of an ultrahigh-power graphite electrode comprises the following steps:

(1) Mixing and stirring triethylene tetramine, concentrated sulfuric acid and fluoroboric acid, placing the mixture in an ice water bath, stirring and reacting for 6-7 hours, and purifying after extraction to obtain polyamino ionic liquid;

(2) Taking concentrated sulfuric acid and concentrated nitric acid, mixing uniformly, adding the carbon nano tube, performing ultrasonic dispersion, stirring at the temperature of 60-65 ℃ for reaction for 2-3h, performing suction filtration and washing to neutrality, and performing vacuum drying to obtain a carboxylated carbon nano tube;

mixing and stirring a carboxylated carbon nanotube, a polyamino ionic liquid and N, N-dimethylformamide, adding dicyclohexylcarbodiimide and 4-dimethylaminopyridine, performing ultrasonic dispersion, stirring and reacting at 80-85 ℃ for 20-24 hours, washing with diethyl ether after the reaction is finished, and performing vacuum drying to obtain a modified carbon nanotube;

(3) Taking coal pitch, heating to melt, adding the modified carbon nano tube, stirring for reaction, standing for cooling, and crushing for later use to obtain pretreated coal pitch;

taking the pretreated coal pitch, a styrene monomer and an acrylonitrile monomer, stirring until the pretreated coal pitch, the styrene monomer and the acrylonitrile monomer are dissolved, reacting for 7-8 hours at 135-140 ℃, taking out after reaction, and drying in vacuum to obtain modified coal pitch;

(4) Taking needle coke, ultrahigh-power graphite electrode roasting fragments, ultrahigh-power graphite electrode graphite fragments, carbon fibers, silicon dioxide and rare earth materials, mixing uniformly, adding melted modified coal pitch, and kneading to form paste; transferring the paste into a press, and pressing for 3-4h at 145-150 ℃ to obtain a semi-finished product of the electrode;

and (3) taking the semi-finished product of the electrode, roasting, graphitizing, processing and molding, and then performing antioxidant treatment to obtain the finished product.

The optimized scheme comprises the following steps:

(1) Taking triethylene tetramine, concentrated sulfuric acid and fluoroboric acid, mixing and stirring for 10-20min, then placing in an ice water bath, stirring and reacting for 6-7h, and purifying after extraction to obtain polyamino ionic liquid;

(2) Taking concentrated sulfuric acid and concentrated nitric acid, mixing uniformly, adding the carbon nano tube, performing ultrasonic dispersion for 1-2h, stirring at 60-65 ℃ for reaction for 2-3h, performing suction filtration and washing to be neutral, and performing vacuum drying to obtain a carboxylated carbon nano tube;

mixing and stirring a carboxylated carbon nanotube, a polyamino ionic liquid and N, N-dimethylformamide for 20-30min, adding dicyclohexylcarbodiimide and 4-dimethylaminopyridine, performing ultrasonic dispersion for 10-15min, stirring and reacting at 80-85 ℃ for 20-24h, washing with diethyl ether after the reaction is finished, and performing vacuum drying at 60-70 ℃ to obtain a modified carbon nanotube;

(3) Taking coal pitch, heating to 170-180 ℃, adding the modified carbon nano tube, stirring for reaction for 30-40min, standing, cooling, and crushing for later use to obtain pretreated coal pitch;

taking the pretreated coal pitch, a styrene monomer and an acrylonitrile monomer, stirring until the pretreated coal pitch, the styrene monomer and the acrylonitrile monomer are dissolved, reacting for 7-8h at 135-140 ℃, taking out after reaction, and carrying out vacuum drying for 10-12h at 120 ℃ under the vacuum degree of-0.1 MPa to obtain modified coal pitch;

(4) Taking needle coke, ultrahigh-power graphite electrode roasting fragments, ultrahigh-power graphite electrode graphite fragments, carbon fibers, silicon dioxide and rare earth materials, dry-mixing for 20-30min, adding molten modified coal pitch after uniformly mixing, and kneading at 200-205 ℃ to form paste; transferring the paste into a press, pressing for 3-4h at 145-150 ℃ under the pressure of 18-20MPa to obtain a semi-finished electrode product;

According to the optimized scheme, in the step (4), the anti-oxidation treatment specifically comprises the following steps:

mixing borax and aluminum phosphate, stirring for 20-30min, adding silicon dioxide and corundum, and stirring uniformly to obtain an impregnation liquid; taking the formed semi-finished product of the electrode, putting the semi-finished product into the steeping liquor, steeping for 5-7h at 60-70 ℃, transferring to vacuum drying at 80-90 ℃, carrying out heat preservation treatment for 10-20min at 115-120 ℃ after drying, carrying out heat preservation treatment for 10-20min when the temperature is increased to 180-190 ℃, carrying out heat preservation for 10-20min when the temperature is increased to 280-300 ℃, and cooling to obtain the finished product.

According to an optimized scheme, in the step of antioxidant treatment, the contents of all components are as follows: by mass, 0.2-0.5 part of borax, 80-82 parts of aluminum phosphate, 3-5 parts of silicon dioxide and 14-16 parts of corundum.

According to an optimized scheme, in the step (1), the molar ratio of triethylene tetramine to concentrated sulfuric acid to fluoroboric acid is 1:1:1.

according to an optimized scheme, in the step (3), the mass ratio of the coal pitch to the modified carbon nano tubes is 25:1; the mass ratio of the pretreated coal pitch to the styrene monomer to the acrylonitrile monomer is 5:3:2.

according to an optimized scheme, in the step (4), the raw materials of each component are as follows: 60-65 parts of needle coke, 5-8 parts of ultrahigh-power graphite electrode roasting fragments, 4-7 parts of ultrahigh-power graphite electrode graphite fragments, 0.5-1 part of carbon fibers, 2-3 parts of silicon dioxide, 0.5-1 part of rare earth materials and 30-35 parts of modified coal pitch.

In an optimized scheme, the rare earth material is one or more of yttrium oxide, lanthanum oxide, cerium oxide and neodymium oxide.

According to an optimized scheme, in the step (2), the carbon nano tubes are bamboo-shaped carbon nano tubes.

According to an optimized scheme, the graphite electrode is prepared by the preparation method of the ultrahigh-power graphite electrode.

Compared with the prior art, the invention has the following beneficial effects:

the invention discloses an ultrahigh-power graphite electrode and a preparation method thereof, wherein needle coke, ultrahigh-power graphite electrode roasting fragments, ultrahigh-power graphite electrode graphite fragments, carbon fibers, silicon dioxide, rare earth materials, modified coal pitch and other components are compounded to improve the oxidation resistance and mechanical property of the graphite electrode, prolong the service life of the electrode and ensure the comprehensive performance of the graphite electrode.

In the processing process, the polyamino ionic liquid is prepared by triethylene tetramine, concentrated sulfuric acid and fluoroboric acid through a one-step synthesis method, then the polyamino ionic liquid and carboxylated carbon nanotubes with acidified surfaces are subjected to a grafting reaction, and in the process, in a dicyclohexyl carbodiimide and 4-dimethylaminopyridine system, amino groups and carboxyl groups on the surfaces of the carbon nanotubes are subjected to a covalent grafting reaction; the processing step can improve the dispersion performance of the carbon nano tube, avoid agglomeration in the subsequent preparation process of the graphite electrode, ensure that the carbon nano tube can be uniformly distributed in the graphite electrode, improve the density of the graphite electrode, enhance the strength and mechanical property of the graphite electrode and improve the electrical property of the graphite electrode; on the other hand, the introduction of the polyamino ionic liquid can react with coal pitch to improve the performance of the coal pitch during the subsequent pretreatment of the coal pitch, so that the smooth proceeding of the polymer modified coal pitch process is ensured.

On the basis, the scheme adopts the polymer to modify the coal pitch, and the coal pitch is modified through free radical polymerization after introducing the styrene monomer and the acrylonitrile monomer so as to improve the carbonization performance of the coal pitch, so that the coal pitch is easier to graphitize and has a more ordered and regular internal structure, thereby improving the mechanical property and the electrical property of the graphite electrode; in the process, because the coal pitch contains various functional groups such as aldehyde group, carbonyl, hydroxyl and the like, and the existence of the aldehyde group and the carbonyl can hinder the free radical polymerization reaction, the polyamino ionic liquid is introduced, one end of the polyamino ionic liquid is subjected to covalent reaction with carboxyl on the surface of the carbon nano tube, and the carbon nano tube is introduced into the coal pitch to improve the mechanical property of the coal pitch, so that the strength of the graphite electrode is improved; the system contains a large amount of amino groups which can react with carbonyl, aldehyde group and the like in the coal pitch to generate Schiff base, so that the influence of the aldehyde group and the carbonyl in the coal pitch is eliminated to a great extent, the modification effect of the polymer on the coal pitch is ensured, and the comprehensive performance of the graphite electrode is ensured.

Meanwhile, silicon dioxide and rare earth materials are introduced, wherein the rare earth materials are yttrium oxide, lanthanum oxide, cerium oxide and neodymium oxide according to the mass ratio of 1:1:1:1, the introduction of the silicon dioxide and the rare earth material can improve the graphitization degree and the comprehensive performance of the graphite electrode, but the proportion of the silicon dioxide and the rare earth material is more important, namely 2-3 parts of the silicon dioxide and 0.5-1 part of the rare earth material, once the proportion exceeds the proportion, the subsequent graphitization of the graphite electrode is influenced, and the performance of the graphite electrode is reduced.

The graphite electrode is prepared by mixing borax, aluminum phosphate, silicon dioxide and corundum to prepare impregnation liquid, the graphite electrode is immersed in the impregnation liquid, and then subsequent heat treatment is carried out, the aluminum phosphate, the silicon dioxide and other components are introduced into the impregnation liquid, the impregnation liquid can enter pits, holes and air holes on the surface of the graphite electrode during impregnation and can be filled and sealed to block oxygen from diffusing to the inside of the electrode, meanwhile, the impregnation liquid can form an anti-oxidation coating on the surface of the graphite electrode, the existence of boric acid can inhibit the diffusion speed of oxygen, inhibit the oxidation of the graphite electrode, and simultaneously improve the high temperature resistance of the graphite electrode.

In one embodiment of the present application, the present application adopts bamboo-like carbon nanotubes instead of conventional carbon nanotubes, and the preparation steps of the bamboo-like carbon nanotubes are as follows: uniformly mixing melamine and deionized water, adding a surfactant and ferric nitrate, uniformly stirring, drying, and carrying out heat treatment at 850 ℃ for 2h in a nitrogen environment to obtain the bamboo-like carbon nanotube, wherein the surfactant is F127; compared with the structure of the conventional carbon nano tube, the bamboo-like structure of the graphite electrode is more excellent, and the mechanical property and the electrical property of the graphite electrode can be further improved.

The invention discloses an ultrahigh-power graphite electrode and a preparation method thereof, the process design is reasonable, the component proportion is proper, the prepared graphite electrode has excellent thermal oxidation resistance and crack resistance, the mechanical property is excellent, the resistivity is reduced, the electrical property is excellent, and the practicability is higher.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1:

(1) Taking triethylene tetramine, concentrated sulfuric acid and fluoroboric acid, mixing and stirring for 10min, then placing the mixture in an ice water bath (-5 ℃) and stirring for reaction for 6h, and purifying after extraction to obtain polyamino ionic liquid; the mol ratio of triethylene tetramine to concentrated sulfuric acid to fluoroboric acid is 1:1:1.

(2) Taking the volume ratio of 3:1, uniformly mixing concentrated sulfuric acid and concentrated nitric acid, adding the carbon nano tube, ultrasonically dispersing for 1h, stirring and reacting for 3h at the temperature of 60 ℃, filtering and washing to be neutral, and drying in vacuum to obtain a carboxylated carbon nano tube;

mixing and stirring a carboxylated carbon nanotube, a polyamino ionic liquid and N, N-dimethylformamide for 20min, adding dicyclohexylcarbodiimide and 4-dimethylaminopyridine, performing ultrasonic dispersion for 10min, stirring and reacting at 80 ℃ for 24h, washing with diethyl ether after the reaction is finished, and performing vacuum drying at 60 ℃ to obtain a modified carbon nanotube; the mass ratio of the carboxylated carbon nanotube to the polyamino ionic liquid is 1:15;

(3) Taking coal pitch, heating to 170 ℃, adding the modified carbon nano tube, stirring for reacting for 40min, standing, cooling, and crushing for later use to obtain pretreated coal pitch; the mass ratio of the coal pitch to the modified carbon nano tube is 25:1;

taking the pretreated coal pitch, a styrene monomer and an acrylonitrile monomer, stirring until the pretreated coal pitch, the styrene monomer and the acrylonitrile monomer are dissolved, reacting for 8 hours at 135 ℃, taking out after the reaction, and drying for 10 hours at 120 ℃ in vacuum with the vacuum degree of-0.1 MPa to obtain modified coal pitch; the mass ratio of the pretreated coal pitch to the styrene monomer to the acrylonitrile monomer is 5:3:2.

(4) Taking needle coke, ultrahigh-power graphite electrode roasting fragments, ultrahigh-power graphite electrode graphite fragments, carbon fibers, silicon dioxide and rare earth materials, dry-mixing for 20min, adding molten modified coal pitch after uniform mixing, and kneading at 200 ℃ to form paste; transferring the paste into a press, pressing for 4 hours at 145 ℃ and under the pressure of 20MPa to obtain a semi-finished electrode product; the raw materials of the components are as follows: 60 parts of needle coke, 5 parts of ultra-high power graphite electrode roasting fragments, 5 parts of ultra-high power graphite electrode graphite fragments, 0.5 part of carbon fiber, 2 parts of silicon dioxide, 1 part of rare earth material and 35 parts of modified coal pitch; the rare earth material is yttrium oxide, lanthanum oxide, cerium oxide and neodymium oxide according to the mass ratio of 1:1:1:1 and mixing.

Mixing and stirring borax and aluminum phosphate for 20min, adding silicon dioxide and corundum, and uniformly stirring to obtain a dipping solution; wherein the contents of the components are as follows: 0.5 part of borax, 80 parts of aluminum phosphate, 4 parts of silicon dioxide and 15 parts of corundum by mass.

Taking the electrode semi-finished product, roasting, graphitizing, carrying out oxidation resistance treatment after machining, taking the machined and molded electrode semi-finished product, placing the electrode semi-finished product in a steeping fluid, steeping for 7 hours at 60 ℃, transferring to 80 ℃ for vacuum drying, carrying out heat preservation treatment at 115 ℃ for 20min after drying, carrying out heat preservation treatment at 180 ℃ for 20min, then carrying out heat preservation at 280 ℃ for 20min, and cooling to obtain the finished product.

Example 2:

(1) Mixing triethylene tetramine, concentrated sulfuric acid and fluoroboric acid, stirring for 15min, placing the mixture in an ice water bath (-5 ℃) and stirring for reaction for 6.5h, and purifying after extraction to obtain polyamino ionic liquid; the mol ratio of triethylene tetramine to concentrated sulfuric acid to fluoroboric acid is 1:1:1.

(2) Taking the volume ratio of 3:1, uniformly mixing concentrated sulfuric acid and concentrated nitric acid, adding the carbon nano tube, ultrasonically dispersing for 1.5h, stirring at 62 ℃ for reacting for 2.5h, filtering, washing to be neutral, and drying in vacuum to obtain a carboxylated carbon nano tube;

mixing and stirring a carboxylated carbon nanotube, a polyamino ionic liquid and N, N-dimethylformamide for 25min, adding dicyclohexylcarbodiimide and 4-dimethylaminopyridine, ultrasonically dispersing for 12min, stirring and reacting at 83 ℃ for 22h, washing with diethyl ether after the reaction is finished, and performing vacuum drying at 65 ℃ to obtain a modified carbon nanotube; the mass ratio of the carboxylated carbon nanotube to the polyamino ionic liquid is 1:15;

(3) Taking coal pitch, heating to 175 ℃, adding the modified carbon nano tube, stirring for reacting for 35min, standing, cooling, and crushing for later use to obtain pretreated coal pitch; the mass ratio of the coal tar pitch to the modified carbon nano tube is 25:1;

taking the pretreated coal pitch, a styrene monomer and an acrylonitrile monomer, stirring until the pretreated coal pitch, the styrene monomer and the acrylonitrile monomer are dissolved, reacting for 7.5 hours at 138 ℃, taking out after reaction, and drying for 11 hours at 120 ℃ in vacuum with the vacuum degree of-0.1 MPa to obtain modified coal pitch; the mass ratio of the pretreated coal pitch to the styrene monomer to the acrylonitrile monomer is 5:3:2.

(4) Taking needle coke, ultrahigh-power graphite electrode roasting fragments, ultrahigh-power graphite electrode graphite fragments, carbon fibers, silicon dioxide and rare earth materials, dry-mixing for 25min, adding molten modified coal pitch after uniformly mixing, and kneading at 203 ℃ to form paste; transferring the paste into a press, pressing for 3.5h at 148 ℃ and under the pressure of 19MPa to obtain a semi-finished product of the electrode; wherein the raw materials of each component are as follows: 60 parts of needle coke, 5 parts of ultra-high power graphite electrode roasting fragments, 5 parts of ultra-high power graphite electrode graphite fragments, 0.5 part of carbon fiber, 2 parts of silicon dioxide, 1 part of rare earth material and 35 parts of modified coal pitch; the rare earth material is yttrium oxide, lanthanum oxide, cerium oxide and neodymium oxide according to the mass ratio of 1:1:1:1 and mixing.

Mixing and stirring borax and aluminum phosphate for 25min, adding silicon dioxide and corundum, and uniformly stirring to obtain a dipping solution; wherein the contents of the components are as follows: by mass, 0.5 part of borax, 80 parts of aluminum phosphate, 4 parts of silicon dioxide and 15 parts of corundum.

Taking the electrode semi-finished product, roasting, graphitizing, processing and forming, then performing antioxidant treatment, taking the processed and formed electrode semi-finished product, placing the processed and formed electrode semi-finished product in a steeping fluid, soaking for 6 hours at 65 ℃, then transferring to vacuum drying at 85 ℃, performing heat preservation treatment at 118 ℃ for 15min after drying, performing heat preservation treatment at 185 ℃ for 15min, then heating to 290 ℃ for 15min, and cooling to obtain a finished product.

Example 3:

(1) Mixing triethylene tetramine, concentrated sulfuric acid and fluoroboric acid, stirring for 20min, placing the mixture in an ice water bath (-5 ℃) and stirring for reaction for 7h, and purifying after extraction to obtain polyamino ionic liquid; the mol ratio of the triethylene tetramine to the concentrated sulfuric acid to the fluoroboric acid is 1:1:1.

(2) Taking the volume ratio of 3:1, adding the carbon nano tube after uniformly mixing concentrated sulfuric acid and concentrated nitric acid, ultrasonically dispersing for 2h, stirring and reacting for 2h at 65 ℃, filtering and washing to be neutral, and drying in vacuum to obtain a carboxylated carbon nano tube;

mixing and stirring a carboxylated carbon nanotube, a polyamino ionic liquid and N, N-dimethylformamide for 30min, adding dicyclohexylcarbodiimide and 4-dimethylaminopyridine, performing ultrasonic dispersion for 15min, stirring and reacting at 85 ℃ for 20h, washing with diethyl ether after the reaction is finished, and performing vacuum drying at 70 ℃ to obtain a modified carbon nanotube; the mass ratio of the carboxylated carbon nanotube to the polyamino ionic liquid is 1:15;

(3) Taking coal pitch, heating to 180 ℃, adding the modified carbon nano tube, stirring for reaction for 30min, standing, cooling, and crushing for later use to obtain pretreated coal pitch; the mass ratio of the coal tar pitch to the modified carbon nano tube is 25:1;

taking the pretreated coal pitch, a styrene monomer and an acrylonitrile monomer, stirring until the pretreated coal pitch, the styrene monomer and the acrylonitrile monomer are dissolved, reacting for 7 hours at 140 ℃, taking out after reaction, and carrying out vacuum drying for 12 hours at 120 ℃ under the vacuum degree of-0.1 MPa to obtain modified coal pitch; the mass ratio of the pretreated coal pitch to the styrene monomer to the acrylonitrile monomer is 5:3:2.

(4) Taking needle coke, ultrahigh-power graphite electrode roasting fragments, ultrahigh-power graphite electrode graphite fragments, carbon fibers, silicon dioxide and rare earth materials, dry-mixing for 30min, adding molten modified coal pitch after uniform mixing, and kneading at 205 ℃ to form paste; transferring the paste into a press, pressing for 3h at 150 ℃ under the pressure of 20MPa to obtain an electrode semi-finished product; the raw materials of the components are as follows: 60 parts of needle coke, 5 parts of ultra-high power graphite electrode roasting fragments, 5 parts of ultra-high power graphite electrode graphite fragments, 0.5 part of carbon fiber, 2 parts of silicon dioxide, 1 part of rare earth material and 35 parts of modified coal pitch; the rare earth material is yttrium oxide, lanthanum oxide, cerium oxide and neodymium oxide according to the mass ratio of 1:1:1:1 and mixing.

Mixing borax and aluminum phosphate, stirring for 30min, adding silicon dioxide and corundum, and stirring uniformly to obtain an impregnation liquid; wherein the contents of the components are as follows: 0.5 part of borax, 80 parts of aluminum phosphate, 4 parts of silicon dioxide and 15 parts of corundum by mass.

Taking the electrode semi-finished product, roasting, graphitizing, carrying out oxidation resistance treatment after machining, taking the machined and molded electrode semi-finished product, placing the electrode semi-finished product in a steeping fluid, steeping for 5 hours at 70 ℃, transferring to vacuum drying at 90 ℃, carrying out heat preservation treatment for 10min at 120 ℃ after drying, carrying out heat preservation treatment for 10min at 190 ℃, then carrying out heat preservation for 10min at 300 ℃, and cooling to obtain the finished product.

Example 4: in example 4, bamboo-like carbon nanotubes were used as the carbon nanotubes, and the remaining process parameters were the same as in example 2.

(1) Mixing triethylene tetramine, concentrated sulfuric acid and fluoroboric acid, stirring for 15min, placing the mixture in an ice water bath (-5 ℃) and stirring for reaction for 6.5h, and purifying after extraction to obtain polyamino ionic liquid; the mol ratio of the triethylene tetramine to the concentrated sulfuric acid to the fluoroboric acid is 1:1:1.

(2) Taking the volume ratio of 3:1, uniformly mixing concentrated sulfuric acid and concentrated nitric acid, adding the carbon nano tube, performing ultrasonic dispersion for 1.5h, stirring at 62 ℃ for reaction for 2.5h, performing suction filtration and washing to neutrality, and performing vacuum drying to obtain a carboxylated carbon nano tube;

mixing and stirring a carboxylated carbon nanotube, a polyamino ionic liquid and N, N-dimethylformamide for 25min, adding dicyclohexylcarbodiimide and 4-dimethylaminopyridine, performing ultrasonic dispersion for 12min, stirring and reacting at 83 ℃ for 22h, washing with diethyl ether after the reaction is finished, and performing vacuum drying at 65 ℃ to obtain a modified carbon nanotube; the mass ratio of the carboxylated carbon nanotube to the polyamino ionic liquid is 1:15;

(3) Taking coal pitch, heating to 175 ℃, adding the modified carbon nano tube, stirring for reacting for 35min, standing, cooling, and crushing for later use to obtain pretreated coal pitch; the mass ratio of the coal pitch to the modified carbon nano tube is 25:1;

(4) Taking needle coke, ultrahigh-power graphite electrode roasting fragments, ultrahigh-power graphite electrode graphite fragments, carbon fibers, silicon dioxide and rare earth materials, dry-mixing for 25min, adding molten modified coal pitch after uniformly mixing, and kneading at 203 ℃ to form paste; transferring the paste into a press, pressing for 3.5h at 148 ℃ and under the pressure of 19MPa to obtain a semi-finished product of the electrode; the raw materials of the components are as follows: 60 parts of needle coke, 5 parts of ultra-high power graphite electrode roasting fragments, 5 parts of ultra-high power graphite electrode graphite fragments, 0.5 part of carbon fiber, 2 parts of silicon dioxide, 1 part of rare earth material and 35 parts of modified coal pitch; the rare earth material is yttrium oxide, lanthanum oxide, cerium oxide and neodymium oxide according to the mass ratio of 1:1:1:1 and mixing.

Mixing borax and aluminum phosphate, stirring for 25min, adding silicon dioxide and corundum, and stirring uniformly to obtain an impregnation liquid; wherein the contents of the components are as follows: by mass, 0.5 part of borax, 80 parts of aluminum phosphate, 4 parts of silicon dioxide and 15 parts of corundum.

Taking the electrode semi-finished product, roasting, graphitizing, carrying out oxidation resistance treatment after machining, taking the machined and molded electrode semi-finished product, placing the electrode semi-finished product in a soaking solution, soaking for 6h at 65 ℃, transferring to 85 ℃, carrying out vacuum drying, carrying out heat preservation treatment for 15min at 118 ℃, carrying out heat preservation treatment for 15min at 185 ℃, carrying out heat preservation treatment for 15min at 290 ℃, and cooling to obtain the finished product.

Comparative example 1: in comparative example 1, the carbon nanotubes were not pretreated with polyamino ionic liquid, and the remaining process parameters were identical to those of example 2.

(1) Taking the volume ratio of 3:1, uniformly mixing concentrated sulfuric acid and concentrated nitric acid, adding the carbon nano tube, performing ultrasonic dispersion for 1.5h, stirring at 62 ℃ for reaction for 2.5h, performing suction filtration and washing to neutrality, and performing vacuum drying to obtain a modified carbon nano tube;

(2) Taking coal pitch, heating to 175 ℃, adding the modified carbon nano tube, stirring for reacting for 35min, standing, cooling, and crushing for later use to obtain pretreated coal pitch; the mass ratio of the coal pitch to the modified carbon nano tube is 25:1;

(3) Taking needle coke, ultrahigh-power graphite electrode roasting fragments, ultrahigh-power graphite electrode graphite fragments, carbon fibers, silicon dioxide and rare earth materials, dry-mixing for 25min, adding molten modified coal pitch after uniformly mixing, and kneading at 203 ℃ to form paste; transferring the paste into a press, pressing for 3.5 hours at 148 ℃, wherein the pressure is 19MPa, and obtaining an electrode semi-finished product; wherein the raw materials of each component are as follows: 60 parts of needle coke, 5 parts of ultra-high power graphite electrode roasting fragments, 5 parts of ultra-high power graphite electrode graphite fragments, 0.5 part of carbon fiber, 2 parts of silicon dioxide, 1 part of rare earth material and 35 parts of modified coal pitch; the rare earth material is yttrium oxide, lanthanum oxide, cerium oxide and neodymium oxide according to the mass ratio of 1:1:1:1 and mixing.

Mixing borax and aluminum phosphate, stirring for 25min, adding silicon dioxide and corundum, and stirring uniformly to obtain an impregnation liquid; wherein the contents of the components are as follows: 0.5 part of borax, 80 parts of aluminum phosphate, 4 parts of silicon dioxide and 15 parts of corundum by mass.

Comparative example 2: in comparative example 2, the polyamino ionic liquid was added directly to the coal pitch, and the remaining process parameters were in accordance with example 2.

(1) Taking triethylene tetramine, concentrated sulfuric acid and fluoroboric acid, mixing and stirring for 15min, placing in an ice water bath (-5 ℃) and stirring for reaction for 6.5h, and purifying after extraction to obtain polyamino ionic liquid; the mol ratio of the triethylene tetramine to the concentrated sulfuric acid to the fluoroboric acid is 1:1:1.

(2) Taking the volume ratio of 3:1, uniformly mixing concentrated sulfuric acid and concentrated nitric acid, adding the carbon nano tube, performing ultrasonic dispersion for 1.5h, stirring at 62 ℃ for reaction for 2.5h, performing suction filtration and washing to neutrality, and performing vacuum drying to obtain a modified carbon nano tube;

(3) Taking coal pitch, heating to 175 ℃, adding the modified carbon nano tube and the polyamino ionic liquid, stirring for reacting for 35min, standing, cooling, and crushing for later use to obtain pretreated coal pitch; the mass ratio of the coal tar pitch to the modified carbon nano tube is 25:1; the mass ratio of the coal tar pitch to the polyamino ionic liquid is 25:1.

(4) Taking needle coke, ultrahigh-power graphite electrode roasting fragments, ultrahigh-power graphite electrode graphite fragments, carbon fibers, silicon dioxide and rare earth materials, dry-mixing for 25min, adding molten modified coal pitch after uniformly mixing, and kneading at 203 ℃ to form paste; transferring the paste into a press, pressing for 3.5 hours at 148 ℃, wherein the pressure is 19MPa, and obtaining an electrode semi-finished product; the raw materials of the components are as follows: 60 parts of needle coke, 5 parts of ultra-high power graphite electrode roasting fragments, 5 parts of ultra-high power graphite electrode graphite fragments, 0.5 part of carbon fiber, 2 parts of silicon dioxide, 1 part of rare earth material and 35 parts of modified coal pitch; the rare earth material is yttrium oxide, lanthanum oxide, cerium oxide and neodymium oxide according to the mass ratio of 1:1:1:1 and mixing.

Comparative example 3: in comparative example 3, coal tar pitch and carbon nanotubes were directly dry-blended without pretreatment, and the remaining process parameters were the same as those of example 2.

(3) Taking needle coke, ultrahigh-power graphite electrode roasting fragments, ultrahigh-power graphite electrode graphite fragments, carbon fibers, silicon dioxide, rare earth materials and modified carbon nanotubes, dry-mixing for 25min, adding molten modified coal pitch after uniformly mixing, and kneading at 203 ℃ to form paste; transferring the paste into a press, pressing for 3.5h at 148 ℃ and under the pressure of 19MPa to obtain a semi-finished product of the electrode; wherein the raw materials of each component are as follows: 60 parts of needle coke, 5 parts of ultra-high power graphite electrode roasting fragments, 5 parts of ultra-high power graphite electrode graphite fragments, 0.5 part of carbon fiber, 2 parts of silicon dioxide, 1 part of rare earth material, 35 parts of modified coal pitch and 2 parts of modified carbon nano tubes; the rare earth material is yttrium oxide, lanthanum oxide, cerium oxide and neodymium oxide according to the mass ratio of 1:1:1:1 and mixing.

Mixing and stirring borax and aluminum phosphate for 25min, adding silicon dioxide and corundum, and uniformly stirring to obtain a dipping solution; wherein the contents of the components are as follows: 0.5 part of borax, 80 parts of aluminum phosphate, 4 parts of silicon dioxide and 15 parts of corundum by mass.

Comparative example 4: in comparative example 4, the graphite electrode was not subjected to the oxidation resistance treatment, and the remaining process parameters were the same as those of example 2.

mixing and stirring a carboxylated carbon nanotube, a polyamino ionic liquid and N, N-dimethylformamide for 25min, adding dicyclohexylcarbodiimide and 4-dimethylaminopyridine, performing ultrasonic dispersion for 12min, stirring and reacting at 83 ℃ for 22h, washing with diethyl ether after the reaction is finished, and performing vacuum drying at 65 ℃ to obtain a modified carbon nanotube; the mass ratio of the carboxylated carbon nanotubes to the polyamino ionic liquid is 1:15;

And (4) taking the semi-finished product of the electrode, roasting, graphitizing, and processing and forming to obtain a finished product.

In the above examples, the particle size composition of the needle coke was: 12-18% of 16-22mm, 10-15% of 6-16mm, 10-14% of 2-6mm, 22-33% of 0.075-0.5mm and 27-42% of less than 0.075 mm. The particle sizes of the ultrahigh power graphite electrode roasting fragments and the ultrahigh power graphite electrode graphite fragments are both 2-4mm; the coal pitch is medium temperature coal pitch.

Detection experiment:

1. taking the graphite electrode samples prepared in the examples 1-4 and the comparative examples 1-4, detecting the mechanical property and the electrical property, and recording data as follows:

item	Example 1	Example 2	Example 3	Example 4
					Bulk density g/cm ³	1.73	1.74	1.73	1.75
Resistivity mu omega m	4.1	3.9	4.2	4.0
					Flexural strength MPa	13.1	13.7	13.2	14.0
Coefficient of thermal expansion 10 ^-6 /℃	1.23	1.20	1.22	1.22
					Item	Comparative example 1	Comparative example 2	Comparative example 3
Resistivity mu omega m	4.9	4.7	4.4
					Flexural strength MPa	12.8	13.1	13.3
Coefficient of thermal expansion of DEG C	1.30	1.31	1.28

2. Resistance to thermal oxidation: taking the samples prepared in the example 2 and the comparative example 4, drying at 200 ℃, transferring to 800 ℃ and 1000 ℃, preserving heat for 2 hours, cooling along with the furnace, measuring and recording the mass difference before and after heat preservation, and calculating the weight loss rate;

item	Example 2	Comparative example 4
			800 ℃ for 2h; percent weight loss	1.67％	18.86％
1000 ℃ for 2h; percent weight loss	4.45％	26.47％

And (4) conclusion: the invention discloses an ultrahigh-power graphite electrode and a preparation method thereof, the process design is reasonable, the component proportion is proper, the prepared graphite electrode has excellent thermal oxidation resistance and crack resistance, the mechanical property is excellent, the resistivity is reduced, the electrical property is excellent, and the practicability is higher.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described above, or equivalents may be substituted for elements thereof. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A preparation method of an ultrahigh-power graphite electrode is characterized by comprising the following steps: the method comprises the following steps:

(3) Taking coal tar pitch, heating to melt, adding the modified carbon nano tube, stirring for reaction, standing for cooling, and crushing for later use to obtain pretreated coal tar pitch;

(4) Taking needle coke, ultrahigh-power graphite electrode roasting fragments, ultrahigh-power graphite electrode graphite fragments, carbon fibers, silicon dioxide and rare earth materials, mixing uniformly, adding melted modified coal pitch, and kneading to form paste; transferring the paste into a press, and pressing for 3-4h at 145-150 ℃ to obtain a semi-finished electrode product;

taking the semi-finished product of the electrode, roasting, graphitizing, processing and molding, and then performing antioxidant treatment to obtain a finished product;

in the step (1), the mol ratio of triethylene tetramine to concentrated sulfuric acid to fluoroboric acid is 1:1:1; in the step (4), the raw materials of each component are as follows: 60-65 parts of needle coke, 5-8 parts of ultrahigh-power graphite electrode roasting fragments, 4-7 parts of ultrahigh-power graphite electrode graphite fragments, 0.5-1 part of carbon fibers, 2-3 parts of silicon dioxide, 0.5-1 part of rare earth materials and 30-35 parts of modified coal pitch; in the step (3), the mass ratio of the coal pitch to the modified carbon nano tube is 25:1; the mass ratio of the pretreated coal pitch to the styrene monomer to the acrylonitrile monomer is 5:3:2; the mass ratio of the carboxylated carbon nanotube to the polyamino ionic liquid is 1:15.

2. the method for preparing an ultra-high power graphite electrode according to claim 1, wherein: the method comprises the following steps:

(2) Taking concentrated sulfuric acid and concentrated nitric acid, uniformly mixing, adding the carbon nano tube, ultrasonically dispersing for 1-2h, stirring and reacting for 2-3h at the temperature of 60-65 ℃, filtering and washing to be neutral, and drying in vacuum to obtain a carboxylated carbon nano tube;

3. The method for preparing an ultra-high power graphite electrode according to claim 2, wherein: in the step (4), the anti-oxidation treatment specifically comprises the following steps:

mixing borax and aluminum phosphate, stirring for 20-30min, adding silicon dioxide and corundum, and stirring uniformly to obtain an impregnation liquid;

taking the formed semi-finished product of the electrode, putting the semi-finished product into a steeping liquor, steeping for 5-7 hours at 60-70 ℃, transferring to vacuum drying at 80-90 ℃, carrying out heat preservation treatment for 10-20min at 115-120 ℃ after drying, carrying out heat preservation treatment for 10-20min at 180-190 ℃, then carrying out heat preservation for 10-20min at 280-300 ℃, and cooling to obtain a finished product;

in the step of antioxidant treatment, the contents of the components are as follows: 0.2-0.5 part of borax, 80-82 parts of aluminum phosphate, 3-5 parts of silicon dioxide and 14-16 parts of corundum by mass.

4. The method for preparing an ultra-high power graphite electrode according to claim 2, wherein: the rare earth material is one or more of yttrium oxide, lanthanum oxide, cerium oxide and neodymium oxide.

5. The method for preparing an ultra-high power graphite electrode according to claim 2, wherein: in the step (2), the carbon nano tube is a bamboo-shaped carbon nano tube.

6. The graphite electrode prepared by the method for preparing an ultra-high power graphite electrode according to any one of claims 1 to 5.