阅读说明：本技术 一种石墨电极及其制备方法 (Graphite electrode and preparation method thereof ) 是由 廖龙辉 于 2021-09-27 设计创作，主要内容包括：本发明涉及一种石墨电极及其制备方法,所述石墨电极包括石墨芯材以及附着于石墨芯材表面的涂层,所述涂层的材质为陶瓷和复合金属的混合物,所述复合金属由金属Ⅰ和金属Ⅱ组成,所述金属Ⅰ为铝和/或钛,所述金属Ⅱ选自钨、钽、铁、镍、钴、铜、锰中的至少一种,该石墨电极不仅电阻率低,而且还能够明显降低石墨损耗,极具工业应用前景。(The invention relates to a graphite electrode and a preparation method thereof, wherein the graphite electrode comprises a graphite core material and a coating attached to the surface of the graphite core material, the coating is made of a mixture of ceramic and composite metal, the composite metal is composed of metal I and metal II, the metal I is aluminum and/or titanium, the metal II is at least one selected from tungsten, tantalum, iron, nickel, cobalt, copper and manganese, and the graphite electrode has low resistivity, can obviously reduce graphite loss and has great industrial application prospect.)

1. A graphite electrode, characterized in that: the graphite electrode comprises a graphite core material and a coating attached to the surface of the graphite core material, wherein the coating is made of a mixture of ceramic and composite metal, the composite metal is composed of a metal I and a metal II, the metal I is aluminum and/or titanium, and the metal II is at least one selected from tungsten, tantalum, iron, nickel, cobalt, copper and manganese.

2. The graphite electrode of claim 1, wherein: the mass ratio of the metal I to the metal II is (7-11): 1.

3. the graphite electrode of claim 2, wherein: the mass ratio of the metal I to the metal II is 9: 1.

4. the graphite electrode of claim 1, wherein: the metal II is selected from at least one of iron, nickel, tungsten and tantalum, and the mass ratio of the ceramic to the metal I to the metal II is (4-7): (3-6): 1.

5. the graphite electrode of claim 4, wherein: the mass ratio of the ceramic to the metal I to the metal II is 5: 4: 1.

6. the graphite electrode of claim 1, wherein: the thickness of the coating is 0.3-0.5 cm.

7. The graphite electrode of claim 1, wherein: the ceramic is silicon dioxide or silicon nitride ceramic.

8. The graphite electrode of claim 1, wherein: the mass content of the composite metal in the coating is not less than 30%.

9. The graphite electrode of claim 8, wherein: the mass content of the composite metal in the coating is 40-50%.

10. The method for producing a graphite electrode as claimed in any one of claims 1 to 9, characterized in that: the method includes forming a coating layer on a surface of a graphite core material by a thermal spraying method.

Technical Field

The invention relates to the field of graphite electrodes, in particular to a graphite electrode and a preparation method thereof.

Background

Graphite electrodes are important conductive materials for metallurgical applications. The graphite electrode is mainly applied to electric furnace steelmaking, current is led into the furnace by the graphite electrode, strong current generates arc discharge at the lower end of the electrode through gas, and heat generated by the arc is utilized for smelting. However, the graphite electrode is very severely lost in the steel-making process, and is generally divided into active loss and reactive loss. The active loss is the oxidation consumption of the side surface of the electrode and the gasification and sublimation consumption of the lower end surface of the electrode in the power transmission process. The reactive loss mainly comes from electrode breakage, falling, chipping and the like. The reduction of the loss of the graphite electrode has a very important significance for reducing the smelting cost of the electric furnace, and has become the key point of research of researchers in recent years.

CN111892833A discloses a method for reducing the loss of a graphite electrode, which comprises the step of carrying out heat treatment on the graphite electrode after dipping by using a superconductive graphite electrode nano antioxidant, wherein the superconductive graphite electrode nano antioxidant consists of 80-100 parts by weight of water, 20-40 parts by weight of ceramic powder, 20-25 parts by weight of graphene, 10-25 parts by weight of polyethylene glycol, 6-12 parts by weight of stabilizer (mixture of meglumine and zirconium nitride), 5-10 parts by weight of antioxidant additive (mixture of expanded calcium, vanadium diboride and sodium dihydrogen phosphate) and 10-15 parts by weight of polyvinyl alcohol, so that a barrier layer for preventing oxygen and reaction products from diffusing into the graphite electrode can be formed, and the breaking strength of the graphite electrode can be improved, thereby reducing the loss of the graphite electrode.

CN111996331A discloses a smelting method for reducing graphite electrode consumption of an electric arc furnace, which comprises the following steps: (a) adding a first batch of scrap iron and steel materials into the electric arc furnace, transmitting power, performing oxygen combustion fluxing when the power consumption is more than or equal to 70 kwh/ton, performing oxygen blowing fluxing when the melting rate of the first batch of scrap iron and steel materials reaches 70-80%, adding lime, and blowing carbon powder to make foamed slag; (b) after slagging is finished, when the melting rate of the first batch of waste steel and iron materials reaches 90-95%, continuously adding a second batch of waste steel and iron materials into the electric arc furnace, transmitting power, carrying out oxygen combustion fluxing when the power consumption is more than or equal to 70 kwh/ton, and carrying out oxygen blowing fluxing when the melting rate of the second batch of waste steel and iron materials reaches 70-80%, and blowing carbon powder; (c) when the melting rate of the second batch of waste iron and steel materials reaches 90-95%, continuously adding a third batch of waste iron and steel materials into the electric arc furnace, and repeating the operation of the step b to obtain a metallurgical melt; (d) blowing oxygen to decarbonize the metallurgical melt obtained in the step (c), blowing carbon powder to slag and bury an arc, heating to a temperature of more than or equal to 1580 ℃, and discharging 45-55% of steel slag when the temperature is more than or equal to 1610 ℃, wherein the components meet the requirements for organization and steel tapping, and the steel retention amount in the electric arc furnace after steel tapping is 18-22 wt% of the total weight of molten steel; (e) repeating the operations from the step (a) to the step (d) to continue the next electric arc furnace smelting; in the steps (a) to (d), the ultrahigh-power graphite electrode is cooled in a full-water spray cooling mode while power transmission is started, so that the length of the red hot electrode at the lower end of the ultrahigh-power graphite electrode is not more than 800 mm.

Disclosure of Invention

The invention aims to provide a graphite electrode capable of obviously reducing graphite loss and a preparation method thereof.

As known to those skilled in the art, the method for reducing the graphite loss by disposing a coating on the surface of a graphite electrode needs to take into consideration the conductivity, resistivity, thermal expansion and contraction amplitude, etc. of the coating, and the coating needs to have the characteristics of good conductivity, low resistivity, and small thermal expansion and contraction amplitude, and also needs to be capable of well protecting a graphite core material. In addition, since the surface of the graphite core material is smooth, it is difficult to form a coating layer having high bonding strength on the surface thereof. Therefore, the selection of the coating material and the method of forming a coating layer on the smooth graphite core material to prevent graphite loss have been technical difficulties in the art. After intensive research, the inventor of the invention finds that the graphite coating is formed by taking ceramic and/or composite metal (aluminum and/or titanium and other metal composites) as a material and adopting a thermal spraying technology, so that the coating has the advantages of good conductivity, low resistivity and small expansion and contraction amplitude, and the graphite loss can be obviously reduced. Based on this, the present invention has been completed.

The specific scheme is as follows:

a graphite electrode comprises a graphite core material and a coating attached to the surface of the graphite core material, wherein the coating is made of a mixture of ceramic and composite metal, the composite metal is composed of a metal I and a metal II, the metal I is aluminum and/or titanium, and the metal II is at least one selected from tungsten, tantalum, iron, nickel, cobalt, copper and manganese.

Further, the mass ratio of the metal I to the metal II is (7-11): 1.

further, the mass ratio of the metal I to the metal II is 9: 1.

further, the metal II is selected from at least one of iron, nickel, tungsten and tantalum, and the mass ratio of the ceramic to the metal I to the metal II is (4-7): (3-6): 1.

further, the mass ratio of the ceramic to the metal I to the metal II is 5: 4: 1.

furthermore, the thickness of the coating is 0.3-0.5 cm.

Further, the ceramic is silicon dioxide or silicon nitride ceramic.

Further, the mass content of the composite metal in the coating is not less than 30%.

Further, the mass content of the composite metal in the coating is 40-50%.

The present invention also provides a method for producing the graphite electrode as described in any one of the above, which comprises forming a coating layer on the surface of a graphite core material by a thermal spraying method.

The graphite electrode provided by the invention not only has low resistivity, but also can obviously reduce graphite loss, and has great industrial application prospect.

Detailed Description

The present invention will be described in detail below by way of examples. The examples of embodiments are intended to be illustrative of the invention and are not to be construed as limiting the invention. The examples do not specify particular techniques or conditions, and are performed according to the techniques or conditions described in the literature in the art or according to the product specifications. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.

Example 1

This example is intended to illustrate a graphite electrode and a method for manufacturing the same, the graphite electrode including a graphite core material and a coating layer attached to a surface of the graphite core material, the graphite core material being a cylinder having a diameter d of 300mm and a length of 1600mm, the coating layer having a thickness of 3mm, and being made of silicon dioxide, aluminum, and iron in a mass ratio of 4: 3: 1.

The coating is attached to the surface of the graphite core material in a plasma thermal spraying mode, and the method comprises the following steps:

s1, providing a graphite core material, performing oil and grease removal treatment on the surface of the graphite core material, and cleaning and preheating by using plasma flame;

s2, thermal spraying of silicon dioxide, aluminum and iron powder is carried out on BSX-APS-8OKW type plasma spraying equipment of New Material science and technology Limited, Baishixing, Xiamen, and the specific thermal spraying parameters are shown in Table 1. It should be noted here that the powder feeding rate is not the mass ratio of each component in the coating layer because the adhesion efficiency of the ceramic and the composite metal is different.

Example 2

This example is intended to illustrate a graphite electrode and a method for manufacturing the same, the graphite electrode including a graphite core material and a coating layer attached to a surface of the graphite core material, the graphite core material being a cylinder having a diameter d of 300mm and a length of 1600mm, the coating layer having a thickness of 5mm, and being made of silica, aluminum, titanium, iron, and nickel in a mass ratio of 5: 2: 1: 1: 1.

The coating is attached to the surface of the graphite core material in a plasma thermal spraying mode, and the method comprises the following steps:

s1, providing a graphite core material, performing oil and grease removal treatment on the surface of the graphite core material, and cleaning and preheating by using plasma flame;

s2, thermal spraying of silicon dioxide, aluminum, titanium, iron and nickel powders is carried out on XXXXX model plasma spraying equipment of XXXXX company, and specific thermal spraying parameters are shown in Table 1.

Example 3

This example is intended to illustrate a graphite electrode and a method for producing the same, the graphite electrode including a graphite core material and a coating layer attached to a surface of the graphite core material, the graphite core material being a cylinder having a diameter d of 300mm and a length of 1600mm, the coating layer having a thickness of 4mm, and being made of silica, titanium, iron, and nickel in a mass ratio of 5: 2: 1: 2, or a mixture thereof.

The coating is attached to the surface of the graphite core material in a plasma thermal spraying mode, and the method comprises the following steps:

s1, providing a graphite core material, performing oil and grease removal treatment on the surface of the graphite core material, and cleaning and preheating by using plasma flame;

s2, thermal spraying of silicon dioxide, aluminum, titanium, iron and nickel powder is carried out on BSX-APS-8OKW type plasma spraying equipment of New Material science and technology Limited, Baishixing, Xiamen, and specific thermal spraying parameters are shown in Table 1.

Example 4

This example is intended to illustrate a graphite electrode and a method for manufacturing the same, the graphite electrode including a graphite core material and a coating layer attached to a surface of the graphite core material, the graphite core material being a cylinder having a diameter d of 300mm and a length of 1600mm, the coating layer having a thickness of 4mm and being made of silicon nitride, titanium, iron, and nickel in a mass ratio of 5: 2: 1: 2, or a mixture thereof.

The coating is attached to the surface of the graphite core material in a plasma thermal spraying mode, and the method comprises the following steps:

s1, providing a graphite core material, performing oil and grease removal treatment on the surface of the graphite core material, and cleaning and preheating by using plasma flame;

s2, thermal spraying of silicon dioxide, aluminum, titanium, iron and nickel powder is carried out on BSX-APS-8OKW type plasma spraying equipment of New Material science and technology Limited, Baishixing, Xiamen, and specific thermal spraying parameters are shown in Table 1.

Comparative example 1

A graphite composite material was prepared by following the procedure of example 1, except that aluminum was not added to the coating layer and the remaining conditions were the same as in example 1, to obtain a reference graphite electrode.

Comparative example 2

A graphite composite material was prepared in the same manner as in example 4 except that titanium was not added to the coating layer, and the remaining conditions were the same as in example 4, to obtain a reference graphite electrode.

Comparative example 3

Uncoated graphite electrode, the diameter d of the graphite electrode is 300mm, and the length is 1600 mm.

Test example

(1) Resistivity: the graphite electrodes prepared in the examples and the comparative examples are measured according to the regulation of the sixth chapter (field measurement of graphite electrode products) in YB/T120-1997, and the obtained results are shown in Table 2;

(2) oxidation resistance: in an air environment, the graphite electrode was heated to 1400 ℃ by energization, the temperature was maintained for 60 minutes, cooling was performed after the time was reached by deenergization, and the weight loss of the graphite electrode before and after energization was measured, and the results are shown in table 2.

As can be seen from the data in Table 2, the graphite electrode with the ceramic-composite metal coating provided by the invention hardly increases the resistivity compared with the graphite electrode without the coating, but greatly reduces the oxidation weight loss of the graphite electrode, can obviously reduce the graphite loss, and has great industrial application prospects.

While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.