CN109735730B

CN109735730B - Preparation method of plasma torch electrode material

Info

Publication number: CN109735730B
Application number: CN201910094235.4A
Authority: CN
Inventors: 徐智; 熊新; 饶耀
Original assignee: WUHAN TIANHE TECHNOLOGY CO LTD
Current assignee: WUHAN TIANHE TECHNOLOGY CO LTD
Priority date: 2019-01-30
Filing date: 2019-01-30
Publication date: 2021-04-06
Anticipated expiration: 2039-01-30
Also published as: CN109735730A

Abstract

The invention discloses a preparation method of a plasma torch electrode material, which comprises the following steps: 1) selection of raw materials: selecting copper and rare earth elements as raw materials; 2) preparing a molten liquid: placing the raw materials in an electric arc furnace, stirring and heating to obtain molten liquid; 3) manufacturing a bar stock: pouring the prepared molten liquid into a circular mold to be cast into a rough blank, and processing and forming the rough blank into a bar; 4) and (3) keeping the temperature of the bar at 300-600 ℃ for more than 20min, annealing, and cooling to obtain the plasma torch electrode material. The method has the advantages of simple preparation process and low processing cost, is suitable for industrial production, and the electrode material prepared by the method has better conductivity, reduces the working temperature of the electrode material during use, reduces the ablation degree and speed of the electrode material, and prolongs the service life of the electrode material.

Description

Preparation method of plasma torch electrode material

Technical Field

The invention relates to the technical field of plasma, in particular to a preparation method of a plasma torch electrode material.

Background

With the continuous development of science and technology, the plasma technology is widely applied. The method is mainly applied to the fields of plasma ignition, plasma spraying, metal smelting, nano material manufacturing by plasma heating, cutting, waste incineration and waste treatment and the like.

The electrode is the core component of the plasma torch, the electrode is the channel of the plasma arc, which is necessarily ablated by high temperature. If an oxidizing gas is used as the working gas, it is also subject to high-temperature oxidative corrosion. The selection of the electrode material is related to the service life of the electrode of the plasma torch, if the service life is short, the use loss and the maintenance cost of the plasma torch can be increased, and the frequent replacement of the electrode limits the use range of the plasma torch.

Most of the currently widely used plasma torch point electrode materials are carbon rods and pure copper, although the carbon rods have the advantages of high melting point and good electric and thermal conductivity, the carbon rods are easy to oxidize at high temperature, and similarly, the metal copper has good electric and thermal conductivity and low melting point, so that the electric conductivity is reduced and the ablation speed is increased after the carbon rods are easy to oxidize, the high-temperature environment of the cathode is difficult to bear, and in addition, the electronic work functions of the carbon rods and the copper are large, so that the cathode is easy to ablate, the service life is shortened, and the use cost is increased.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: overcomes the defects of the prior art and provides a preparation method of the plasma torch electrode material with simple process and low cost.

The technical scheme adopted by the invention for solving the technical problems is as follows: a preparation method of a plasma torch electrode material comprises the following steps: 1) selection of raw materials: selecting copper and any one element of yttrium, hafnium, tungsten, tantalum and niobium as raw materials; 2) preparing a molten liquid: placing the raw materials in an electric arc furnace, stirring and heating to obtain molten liquid; 3) manufacturing a bar stock: pouring the prepared molten liquid into a circular mold to be cast into a rough blank, and processing and forming the rough blank into a bar; 4) and (3) keeping the temperature of the bar at 300-600 ℃ for more than 20min, annealing, and cooling to obtain the plasma torch electrode material.

When the holding time is less than 20min, the grain size of the internal structure of copper and any one element of yttrium, hafnium, tungsten, tantalum and niobium is larger, and the prepared electrode has poor conductivity.

Preferably, the heat preservation time in the step 4) is 20min-40 min.

Any one element of yttrium, hafnium, tungsten, tantalum and niobium has the characteristics of high melting point and low work function, and the work temperature of the material can be reduced by reducing the work function under the same current density by adopting any one element of yttrium, hafnium, tungsten, tantalum and niobium as the raw material of the electrode material, so that the ablation degree of the electrode material is reduced, the service life of the electrode material is prolonged, and the use cost is reduced.

The work function of yttrium is 3.1ev, the work function is lower than that of hafnium, tungsten, tantalum and niobium, yttrium is selected as the raw material of the electrode material, and compared with hafnium, tungsten, tantalum and niobium, the work function can be further reduced, the working temperature of the material is further reduced, and the ablation speed of the electrode material is reduced.

Further, the content of copper in the raw material is 99.9% -99.99%, and the content of any one element of yttrium, hafnium, tungsten, tantalum and niobium is 0.01% -0.1%. Because copper has better heat conduction and electric conduction properties, the heat conduction and electric conduction properties of any one element of yttrium, hafnium, tungsten, tantalum and niobium are lower than that of copper, if the content of copper is lower than 99.9%, the content of any one element of yttrium, hafnium, tungsten, tantalum and niobium is higher than 0.1%, the heat conduction and electric conduction properties of the electrode material are reduced.

Furthermore, the purity of the copper is more than 99.5%, and the purity of any one element of yttrium, hafnium, tungsten, tantalum and niobium is more than 99.5%.

Further, the heating temperature in the step 2) is over 1100 ℃, and the heating time is over 20 min. When the heating time is less than 20min, the raw materials are not completely melted, and the prepared electrode has poor conductivity.

Preferably, the heating temperature in the step 2) is 1100-1200 ℃, and the heat preservation time is 20-40 min.

Further, the atmosphere in the arc furnace is any one of vacuum, argon and nitrogen.

Further, the processing and forming mode in the step 3) is any one of cold extrusion, hot extrusion, cold drawing, hot drawing and forging.

Further, the casting mode in the step 3) is metal mold gravity casting.

The invention has the beneficial effects that: the invention provides a preparation method of a plasma torch electrode material, which has simple preparation process and low processing cost and is suitable for industrial production.

Detailed Description

The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention in any way.

Example 1

A preparation method of a plasma torch electrode material comprises the following steps:

1) selection of raw materials: selecting copper with the purity of 99.9 percent and yttrium with the purity of 99.5 percent, weighing 499.7kg of copper and 0.3kg of yttrium as raw materials, wherein the content of copper in the raw materials is 99.94 percent, and the content of yttrium is 0.06 percent;

2) preparing a molten liquid: placing the raw materials in an electric arc furnace, and vacuumizing to 10%^-5Starting an electric arc furnace and magnetic stirring after Pa, stirring and heating the raw materials, and heating for 40min at the temperature when the heating temperature in the electric arc furnace reaches 1220 ℃ to obtain molten liquid;

3) manufacturing a bar stock: pouring the prepared molten liquid into a circular mold to be cast into a rough blank, wherein the casting mode is metal mold gravity casting, and then heating the rough blank to 400 ℃ and forging and pressing the rough blank into a bar;

4) and (3) keeping the temperature of the bar stock at 300 ℃ for 50min, annealing and cooling to obtain the plasma torch electrode material.

Example 2

1) selection of raw materials: selecting copper with the purity of 99.6 percent and yttrium with the purity of 99.9 percent, weighing 299.7kg of copper and 0.3kg of yttrium as raw materials, wherein the copper content in the raw materials is 99.94 percent, and the yttrium content in the raw materials is 0.06 percent;

2) preparing a molten liquid: placing the raw materials in an electric arc furnace, and vacuumizing to 10%^-5After Pa, nitrogen gas is injected to 10^-3Pa, starting an electric arc furnace and magnetic stirring, stirring and heating the raw materials, and heating for 30min at the temperature when the heating temperature in the electric arc furnace reaches 1180 ℃ to obtain molten liquid;

3) manufacturing a bar stock: pouring the prepared molten liquid into a circular mold to be cast into a rough blank, wherein the casting mode is metal mold gravity casting, and then heating the rough blank to 600 ℃ and forging and pressing the rough blank into a bar;

4) and (3) keeping the temperature of the bar stock at 400 ℃ for 40min, then annealing and cooling to obtain the plasma torch electrode material.

Example 3

The present embodiment is different from embodiment 1 in that: 499.95kg of copper and 0.05kg of yttrium are weighed as raw materials, wherein the content of copper in the raw materials is 99.99%, and the content of yttrium is 0.01%.

Example 4

The present embodiment is different from embodiment 1 in that: 499.5kg of copper and 0.5kg of yttrium are weighed as raw materials, wherein the content of copper in the raw materials is 99.9 percent, and the content of yttrium is 0.1 percent.

Comparative example

The comparative example differs from example 1 in that: the raw materials for manufacturing the electrode material only contain copper, and any one element of yttrium, hafnium, tungsten, tantalum and niobium is not added.

The present invention measured the degree of ignition (loss of electrode weight) of the electrode materials prepared in examples 1 to 4 and comparative examples 1 to 2, and the measurement results at an operating current of 450A are shown in the following table:

from the above table, it can be seen that, compared with the comparative example, the electrode material prepared by the method of the present invention has the advantages of reduced resistivity, better conductivity, and significantly lower weight loss than the comparative example, which indicates that the arc ablation resistance of the electrode material is improved, and the ablation rate is reduced.

Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A preparation method of a plasma torch electrode material is characterized by comprising the following steps: the method comprises the following steps: 1) selection of raw materials: selecting copper and any one element of yttrium, hafnium, tungsten, tantalum and niobium as raw materials; 2) preparing a molten liquid: placing the raw materials in an electric arc furnace, stirring and heating to obtain molten liquid; 3) manufacturing a bar stock: pouring the prepared molten liquid into a circular mold to be cast into a rough blank, and processing and forming the rough blank into a bar; 4) and (3) keeping the temperature of the bar at 300-600 ℃ for 20-40min, annealing and cooling to obtain the plasma torch electrode material.

2. A method of preparing a plasma torch electrode material as claimed in claim 1, wherein: the copper content in the raw material is 99.9-99.99%, and the content of any one element of yttrium, hafnium, tungsten, tantalum and niobium is 0.01-0.1%.

3. A method of preparing a plasma torch electrode material as claimed in claim 2, wherein: the purity of the copper is more than 99.5%, and the purity of any one element of yttrium, hafnium, tungsten, tantalum and niobium is more than 99.5%.

4. A method of preparing a plasma torch electrode material as claimed in any of claims 1 to 3, wherein: the heating temperature in the step 2) is more than 1100 ℃, and the heating time is more than 20 min.

5. A method of preparing a plasma torch electrode material as claimed in claim 4, wherein: the atmosphere in the electric arc furnace is any one of vacuum, argon and nitrogen.

6. A method of preparing a plasma torch electrode material as claimed in claim 4, wherein: the processing and forming mode in the step 3) is any one of cold extrusion, hot extrusion, cold drawing, hot drawing and forging.

7. A method of preparing a plasma torch electrode material as claimed in claim 4, wherein: the casting mode in the step 3) is metal mold gravity casting.