CN113056082A - Electrode structure with uniform and stable arcing characteristic and preparation technology thereof - Google Patents
Electrode structure with uniform and stable arcing characteristic and preparation technology thereof Download PDFInfo
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Abstract
The invention discloses an electrode structure with uniform and stable arcing characteristics, which comprises a zirconia layer, a zirconia-zirconia double-phase layer, a zirconium surface layer, a transition layer and a pure copper matrix from the outside to the inside; wherein the zirconium oxide-zirconium double-phase layer is formed by the aggregation of zirconium oxide and metal zirconium; the zirconium surface layer consists of zirconium and a small amount of other metals; the transition layer is a multi-phase structure formed by copper and various heterogeneous metals; the zirconium oxide is formed by in-situ oxidation of metal zirconium on a zirconium surface layer by an arc ablation technology. The invention also discloses a preparation method of the electrode, which comprises two processes of laser cladding and in-situ arc ablation preparation. The electrode ensures strong interface combination on the basis of surface arc ablation resistance and high electric and heat conduction of the matrix, realizes lower electrode ablation rate and more stable electrode structure which are more sustainable than a mechanical embedded cathode structure, and is beneficial to prolonging the service life of the electrode.
Description
Technical Field
The invention relates to an electrode of an arc discharge device, in particular to a composite electrode of multiple metals and a preparation method thereof.
Background
Ablation is an arc plasma processThe inevitable electrode failure process in use. During arc discharge, the two ends of the arc are respectively supported on the surfaces of the cathode and the anode, and the processes of ionization of neutral molecules and the like continuously occur in the arc column. At very high heat input to the arc root (heat flux density, 10)5~108 W/m2) The electrodes are ablated by melt-spraying, evaporation, boiling, etc. The cathode is subjected to high velocity bombardment by heavier positive ions than the anode, and the ablation process is more severe. In order to conduct the heat input that dissipates the arc root as far as possible, some arc plasma application devices use pure copper as the electrode material, such as arc heaters. However, under the comprehensive action of factors such as cathode spots, surface air flow and the like, the heat input of local surface sites is increased rapidly during pure copper arc burning, the electrode material is ablated and accelerated to form an ablated deep hole, and the ablated deep hole is expanded and deepened along with the extension of the arc burning time and evolves into an ablated pit with a millimeter-sized diameter, so that the structural stability of the electrode is threatened.
Studies have shown that when the cathode surface is covered with a high melting point liquid film and the liquid film work function is lower than the substrate, the arc roots tend to preferentially contact the area covered by the liquid film, thereby promoting a uniform ablation process of the electrode and reducing the ablation rate. The arc burning characteristic is common to metal hafnium, zirconium and yttrium electrodes, and is mainly used for arc plasma cutting, when arc burning discharge is carried out, the surface of the electrode is melted, plasma reaction is carried out to generate an oxide layer, the oxide layer has higher melting point and lower work function compared with an electrode substrate, after a liquid film covers the surface of the electrode, the ablation uniformity is improved, and the ablation rate is reduced.
However, metals with the arcing characteristics of oxide liquid films generally have poor thermal conductivity, less than one twentieth that of pure copper. Therefore, the copper sleeve is coated in a water-cooling copper sleeve in a mechanical embedding mode in actual use, and the heat input of the arc root is dissipated. As the arcing time is prolonged, the difference of the thermal expansion of the two is large, a gap is formed on an interface, the heat conduction process is deteriorated, and the burning loss of the electrode is accelerated due to accumulated heat.
Disclosure of Invention
In order to overcome the problems in the prior art, the invention aims to design a copper-based heterogeneous layered structure electrode, which takes pure copper as a substrate, utilizes the good electric and heat conduction capability of the copper and the uniform ablation characteristic of zirconia, realizes the preparation of the copper-based heterogeneous layered structure electrode through a transition layer, interlayer metallurgical bonding and the like, has the uniform ablation characteristic in an oxygen-containing atmosphere, and an oxide film formed in situ after arcing bears arc roots, protects the copper substrate and prolongs the service life of the electrode.
In order to achieve the above object, the specific technical solution of the present invention is as follows:
a copper-based heterogeneous layered structure electrode at least comprises a zirconia layer, a zirconia-zirconium double-phase layer, a zirconium surface layer, a transition layer and a pure copper matrix from the surface to the inside, wherein the zirconia-zirconium double-phase layer is formed by the aggregation of zirconia and metal zirconium; the zirconium surface layer consists of zirconium, a small amount of copper and a small amount of other metals; the transition layer is a multi-phase structure formed by pure copper and other metals, wherein the other metals are any one of chromium, niobium or iron.
The copper-based heterogeneous layered structure electrode is applied to the continuous arc stabilization discharge work and used as a cathode of an arc discharge device, and in the high-temperature arc process, a liquid film is formed on the most surface layer of zirconia to form a molten pool with a molten zirconia-zirconium double-phase layer. The liquid density of the zirconium oxide is lower than that of pure zirconium and the zirconium oxide is insoluble with the pure zirconium, so that the zirconium oxide always gathers on the surface of the molten pool and bears the arc root. Meanwhile, as the melting point of the zirconium oxide is higher than that of pure zirconium at high temperature and the work function is lower than that of the pure zirconium, the temperature of the electrode can be reduced during arcing discharge, the cathode arc root is stably loaded, and the discharge ablation process is homogenized, so that the copper-based heterogeneous layered structure electrode has the characteristics of uniform arc ablation characteristic and low ablation rate. Meanwhile, if the copper-based heterogeneous layered structure electrode works in an oxidizing active atmosphere, the copper-based heterogeneous layered structure electrode continuously oxidizes metal zirconium in a zirconium oxide-zirconium dual-phase layer in continuous arc-stabilizing discharge work, and the burning loss of zirconium oxide on the surface layer is supplemented, so that the uniformity and sustainability of arc-burning discharge are realized, and the stable layered structure of the zirconium oxide layer, the zirconium oxide-zirconium dual-phase layer, the zirconium surface layer, the transition layer and the pure copper substrate from the outside to the inside can still be maintained in the continuous work of the electrode. Moreover, the heat input to the surface of the electrode by the arc root is conducted in time by the pure copper matrix at the bottom of the electrode, so that the heat accumulation in a molten pool is avoided, the structural stability of the electrode is enhanced, and the service life of the electrode is prolonged.
The copper-based heterogeneous layered structure electrode is the best choice for the application of the copper-based heterogeneous layered structure electrode in the active oxidation atmosphere. Certainly, it is undeniable that the copper-based heterogeneous layered structure electrode can also be used in an environment without active oxidation, such as vacuum, for example, when the copper-based heterogeneous layered structure electrode is applied to a vacuum environment for discharging, a metal oxide liquid film on the surface layer of the electrode can still reduce the work function of a cathode, and compared with pure metal zirconium, the ablation rate is lower, and the effect can be generated before the metal oxide on the surface layer is completely consumed; meanwhile, the heat input to the surface of the electrode by the arc root is conducted in time by the pure copper matrix at the bottom of the electrode, so that heat accumulation in a molten pool is avoided, the structural stability of the electrode is enhanced, and the service life of the electrode is prolonged.
Furthermore, the zirconium surface layer, the transition layer and the pure copper substrate are in metallurgical bonding, and the interlayer interface is complete and has no transverse crack.
The electrode has uniform arc ablation characteristics, specifically, the uniform arc ablation characteristics are represented as: in the process of arc burning and ablation of the electrode, the surface of the electrode presents spherical or ellipsoidal bright spots, the discharge is uniform in the bright spots, and the brightness is uniform without local discrete spots.
The invention also provides a preparation method of the copper-based heterogeneous layered structure electrode, the preparation of the electrode is realized by two processes, the two processes are respectively the preparation of a zirconium layer on the surface of a pure copper matrix and the preparation of an ablation-resistant oxide layer on the surface of zirconium, wherein the preparation of the zirconium layer on the surface of the pure copper matrix adopts a high-speed laser cladding method, and the preparation of the ablation-resistant oxide layer on the surface of zirconium adopts an in-situ arc ablation technology.
The preparation of the zirconium layer on the surface of the pure copper matrix adopts block pure copper and two metal powders as raw materials, wherein one metal powder is zirconium powder, and the other metal powder is any one of chromium, niobium and iron, and a high-speed laser cladding method is adopted to prepare the transition layer and the zirconium surface layer in the electrode so as to form three coating layers of the pure copper matrix, the transition layer and the zirconium surface layer. By adopting a high-speed laser cladding method, the dilution rate of each layer and the shape of the surface ridge can be accurately controlled on the basis of realizing multilayer cladding of the surface of a pure copper matrix and ensuring interlayer combination.
The transition layer is required to have high dilutability, has a multiphase structure composed of pure copper and chromium, niobium or iron, and contains copper at not more than 60at%, preferably 40 to 60 at%. Specifically, in the copper-based heterogeneous layered structure electrode of the present invention, the transition layer mainly plays two roles: 1) the copper source is used for providing a certain amount of copper for subsequent zirconium surface layer cladding, so that a proper amount of copper (less than 15at%, preferably 10-15 at%) is dispersed in a zirconium framework of a zirconium surface layer, the zirconium surface layer is prevented from forming pure zirconium, and the sharp increase of the hardness of the surface layer and the embrittlement of a coating layer are induced; 2) stress is released, a certain copper content ensures sufficient strength and plastic deformation capability of the transition layer, stress concentration caused by thermal expansion mismatch of a copper matrix and a zirconium surface layer during cladding and forming is eliminated, and cracking of a coating layer is avoided. Based on the function of the transition layer in the copper-based heterogeneous layered structure electrode, the following properties are required: 1) strictly controlling the copper content of the transition layer to be not higher than 60at%, preferably 40-60 at%, and preventing the over-high dilution rate after cladding the zirconium surface layer to form a brittle copper-zirconium compound grid; 2) the hardness of the transition layer needs to be 300-400 HV, the elongation needs to be higher than 9.5%, and the reasonable transition of the mechanical property from the copper matrix to the zirconium surface layer is realized.
Forming a ridge-shaped structure on the surface of the zirconium surface layer prepared on the surface of the transition layer so as to disperse arc roots; the zirconium surface layer mainly comprises metal zirconium, contains a small amount of copper and a small amount of chromium, niobium or iron, the copper content is not higher than 15at%, preferably 10-15 at%, and a small amount of copper is dispersed in the zirconium framework, so that the situation that pure zirconium is formed to induce the hardness of the surface layer to increase rapidly, a copper-zirconium compound grid is prevented from being formed, and the coating is embrittled is avoided; in addition, the hardness of the zirconium surface layer is controlled to be 600-700 HV, so that the overall structural strength of the electrode is guaranteed, and the electrode is prevented from deforming in the processes of clamping and the like; the thickness of the zirconium surface layer is not less than 450 mu m, and the sufficient service life is ensured.
Specifically, the process for preparing the zirconium layer on the surface of the pure copper matrix by adopting a high-speed laser cladding method comprises the following steps:
(1) placing the block pure copper on a sample table of a high-speed laser cladding platform, and carrying out preheating treatment;
(2) after polishing and removing an oxide skin or a damaged layer on the surface of the pure copper, filling any one of chromium powder, niobium powder or iron powder and zirconium powder into a powder cylinder;
(3) setting cladding parameters; starting cladding, and supplying powder to the powder cylinder filled with chromium powder, niobium powder or iron powder to finish the preparation of the transition layer;
(4) and (4) adjusting cladding parameters, starting cladding after the temperature of a cladding surface is cooled, and supplying powder to a powder cylinder filled with zirconium powder to prepare a zirconium surface layer.
In the step (3), when the transition layer is clad, the cladding is performed at a high power and a proper low powder amount, for example, 2000w, so as to increase the dilution rate of the transition layer and ensure that the copper content in the transition layer is not higher than 60%. When the zirconium surface layer is prepared in the step (4), on the basis of a preparation process of a transition layer, the power is properly reduced, for example, 1800w in embodiment 1, and meanwhile, the working distance is shortened, the moving speed of a cladding head is reduced, and the inter-pass offset is adjusted, so that a small amount (less than 15%) of copper is dispersedly distributed in a zirconium framework of the coating layer, and a ridge-shaped appearance is formed on the surface.
Specifically, during cladding, the cladding head moves back and forth along the horizontal Y direction of the surface of the sample, a cladding layer is clad by crossing the cladding surface once, then the cladding head shifts a set value to the horizontal X direction, and the next cladding process is started. And the movement amount of the inter-pass cladding head in the X direction is the inter-pass offset. For example, in example 1, the shift was 0.18mm in the case of cladding the transition layer, and the shift was increased to 0.36mm in the case of cladding the zirconium surface layer.
The preparation of resistant sintering of corroding oxide layer on zirconium surface adopts normal position electric arc ablation technique, with the last coating zirconium top layer that makes is the negative pole in the preparation of pure copper matrix body surface zirconium layer, after arcing discharge under the oxygen atmosphere, normal position reaction zirconia-zirconium diphase layer, zirconia layer. The process principle is as follows: after the cathode is subjected to arc combustion in an oxygen-containing atmosphere, the zirconium surface layer is melted, the high-activity molten zirconium on the surface of the electrode reacts with arc plasma, zirconium oxide is generated in situ, the density of the liquid zirconium oxide is lower than that of pure zirconium and is insoluble with the pure zirconium, the liquid zirconium oxide is gathered on the surface of a molten pool to form a liquid film and bear an arc root, the molten pool is layered at the moment, the zirconium oxide is on the surface layer, and the zirconium oxide-zirconium two-phase layer is on the bottom layer. Meanwhile, the work function of the zirconium oxide is lower than that of pure zirconium at high temperature, so that the electrode temperature can be effectively reduced and the ablation process can be homogenized during arcing discharge. In the zirconium oxide-zirconium dual-phase layer, the zirconium liquid drops are continuously oxidized to supplement the burning loss of the surface oxide layer, the zirconium layer is melted at the bottom of the molten pool, and the oxidation consumption of the metal liquid drops in the molten pool is supplemented.
Specifically, adopt normal position arc ablation technique to carry out the process that the resistant sintering of erosion oxide layer of zirconium surface was prepared includes:
(I) placing a sample which is prepared by the zirconium layer on the surface of the pure copper matrix in an arc generating device to be used as a cathode;
(II) setting a preheating temperature and a current step-growth program of the electric arc generating device; planning a moving path of an arc root on the surface of the cathode, wherein the track is set in a mode that the arc root traverses the preparation area of the electrode with the layered structure under a single current gradient value;
(III) starting preheating, introducing an oxidizing atmosphere, starting an electric arc generating device, and after the sample reaches a preset preheating temperature, puncturing a gas gap between the sample and an anode, and burning and stabilizing an arc;
(IIII) after reaching the target current according to a preset current step increase program, continuously arcing to finish the preparation of the zirconia layer and the zirconia-zirconium double-phase layer, and finally finishing the electrode preparation.
The preheating temperature and current step increase program is set as follows:
Wherein the preheating in step (III) is performed to increase the reactivity of the surface of the coating with plasma, and release the stress, so as to avoid the zirconium oxide from peeling off due to the difference of the properties of the zirconium oxide and the coating substrate.
The copper-based heterogeneous layered structure electrode disclosed by the invention is based on a layered structure prepared by laser cladding and in-situ arc ablation, can ensure strong interface combination on the basis of surface layer arc ablation resistance and high electric and heat conduction of a matrix, realizes a low electrode ablation rate with more continuity and a more stable electrode structure compared with a mechanical embedded cathode structure, and is beneficial to prolonging the service life of the electrode.
Drawings
FIG. 1 is a schematic view and a cross-sectional optical micrograph of a copper-based hetero-layered structure electrode prepared in each example. Wherein 1 is a pure copper matrix, 2 is a transition layer, 3 is a zirconium surface layer, 4 is a zirconium oxide-zirconium double-phase layer, and 5 is a zirconium oxide layer. FIG. 2 is an optical micrograph of a cross section of example 1 after laser cladding (a) a transition layer and (b) a zirconium surface layer.
Fig. 3 is a current increase curve for the arc-burning ablation preparation process of example 1.
FIG. 4 is a scanning electron micrograph of the surface of the copper-based hetero-layered structure electrode obtained in example 1 (a) an arc discharge at 50A current filter capture image and (b).
FIG. 5 is a scanning electron micrograph of a cross section of the copper-based hetero-layered structure electrode obtained in example 1.
Fig. 6 is an optical micrograph of a cross section of comparative example 1 after laser cladding (a) a transition layer and (b) a zirconium surface layer.
FIG. 7 is a (a) surface electron micrograph and (b) cross-sectional optical micrograph of the copper-based hetero-layered structure electrode obtained after arc ablation in comparative example 1.
Fig. 8 is a current gradient growth curve for the arc burning ablation process of example 2.
FIG. 9 is an optical micrograph of a cross section of an electrode after (a) laser cladding and (b) a cross-sectional scanning electron micrograph after arc burning ablation of example 2.
Detailed Description
The present invention will be described in detail below with reference to specific examples.
The copper-based heterogeneous layered structure electrode prepared in each embodiment takes a pure copper matrix, any one of chromium powder, niobium powder and iron powder and metal zirconium powder as raw materials, wherein the particle size of each metal powder is 300-500 meshes. Firstly, preparing a hafnium layer on the surface of a pure copper matrix by adopting a high-speed laser cladding method to prepare a three-layer coating of the pure copper matrix, a transition layer and a zirconium surface layer in the hafnium-copper composite electrode; and then, preparing a zirconium surface sintering-resistant sintered oxide layer, and preparing a zirconium oxide layer and a zirconium oxide-zirconium double-phase layer in the copper-based heterogeneous layered structure electrode by adopting an in-situ arc ablation technology and taking a coating finally prepared in the preparation of the zirconium layer on the surface of the pure copper substrate as a cathode.
Referring to fig. 1, a schematic flow chart of a process for preparing a zirconium layer on the surface of a pure copper substrate by a high-speed laser cladding method and a copper-based heterogeneous layered structure electrode comprising the pure copper substrate, a transition layer, a zirconium surface layer, a zirconium oxide-zirconium dual-phase layer and a zirconium oxide layer by an in-situ arc ablation technology is obtained, and a cross-sectional optical micrograph of each corresponding layer is obtained.
Example 1:
in this example, a copper-based heterogeneous layered structure electrode was prepared, which includes, from the surface to the inside, a zirconia layer, a zirconia-zirconia two-phase layer, a zirconium surface layer, a niobium-copper transition layer, and a pure copper matrix. The arc stabilizing current in the actual service environment of the electrode is 52A, and the cathode arc burning area is a circle with the diameter of about 4.5 mm. The total power of a fiber laser of a high-speed laser cladding platform used for copper surface laser cladding is 3000W, and the power is continuously adjustable. The purity of the niobium powder and the zirconium powder is higher than 99.5%, the particle size of the powder is 300-500 meshes, and the niobium powder and the zirconium powder are used after being dried in vacuum.
During cladding, the power adjustment range of the laser is 1500-2250W, the working distance (namely the distance between a cladding head and the surface of a cladding) is 13-16 mm, and niobium powder and zirconium powder are respectively arranged in a powder barrel No. 1 and a powder barrel No. 2 which are independently controllable. The process for sequentially melting the copper-niobium transition layer and the zirconium layer on the surface of the copper substrate comprises the following steps:
1. will be 200X 100X 10 mm3The pure copper block body is clamped on a sample table of a laser cladding system by 200 multiplied by 100 mm2As a cladding surface, starting a sample table preheating module, and setting the preheating temperature to be 200 ℃ according to the arc stabilizing service current;
2. removing an oxide layer or a deformation layer on the upper surface of the copper block by using a mechanical polishing tool to ensure that the surface to be clad is smooth;
3. filling a proper amount of niobium powder into a No. 1 powder barrel, setting the cladding power to be 2000W, the rotating speed of a powder disc to be 0.3 r/s, the moving speed to be 0.06 m/s, the deviation to be 0.18mm and the working distance to be 15.5 mm, and starting cladding of a copper-niobium transition layer;
4. after the cladding of the transition layer is finished, filling zirconium powder into a No. 2 powder barrel, adjusting the working distance to 14.5 mm, setting the power to be 1800W, the rotating speed of a powder disc to be 0.3 r/s, the moving speed to be 0.045 m/s and the offset to be 0.36 mm. When the surface temperature of the transition layer is reduced to about 250 ℃, removing an oxide layer, slag and the like on the surface of the coating by using a mechanical polishing device, and starting cladding equipment to complete cladding of the zirconium layer;
5. and naturally cooling the sample to room temperature to finish the laser cladding preparation part of the electrode.
The prepared coating comprises a zirconium layer, a copper-niobium transition layer and a pure copper matrix. The metallographic structure of the cross section of the copper-niobium transition layer prepared by cladding is shown in fig. 2(a), the thickness of the copper-niobium transition layer is about 360 microns, the copper-niobium transition layer is metallurgically bonded with a copper matrix, and the transition layer has no defects such as air holes, cracks and the like. And (3) cladding a zirconium surface layer on the surface of the copper-niobium transition layer for the second time to obtain an electrode section metallographic phase as shown in fig. 2(b), and cladding to form a pure copper-niobium-zirconium layered structure, wherein the zirconium layer surface is in a ridge-shaped appearance, the average thickness of the zirconium layer is more than 470 microns, the zirconium layer is tightly combined with the copper-niobium transition layer, the overall quality of the layered coating structure is good, and the defects of obvious pores and the like are avoided. The test results of the components and the mechanical properties show that the laminated structure is prepared, the copper content of the zirconium layer is about 6.8at percent, and the hardness is 680 HV; the copper content of the copper-niobium transition layer is 48.5at%, the hardness is 390 HV, and the elongation is 9.8%.
Then, taking the prepared layered coating after cladding as a cathode, carrying out arc discharge in an active atmosphere, melting zirconium on the surface of the coating, then reacting with arc plasma, and generating a zirconium oxide-zirconium double-phase layer and a zirconium oxide surface layer in situ, wherein the preparation process comprises the following steps:
1. and (3) preparing the coating sample into an electrode sample with a specific size by mechanical processing modes such as linear cutting and the like, and soaking the electrode sample in acetone to remove oil stains, oxide scales and the like. Then, polishing the zirconium surface layer by 600-2000-mesh abrasive paper to make the surface smooth;
2. and clamping the polished coating electrode on an ablation test platform to serve as a cathode. Starting an external active gas source of the ablation device for 2 min to fill an arc space with active atmosphere;
3. and setting the surface of the coating to be 4 mm away from the tip of the anode according to the height of the cathode sample, setting the preheating temperature to be 200 ℃, and setting a current increasing program and an arc root motion track according to the arc stabilizing service current. Wherein the arc root motion trail is: in the circular preparation area with the diameter of 4.5mm, in the arc stabilizing time under each gradient current, the arc root moves around the center of the preparation area in an approaching mode, and the whole preparation area is traversed. A gradient current increasing program is shown in fig. 3, five gradients of 10, 20, 30, 40 and 50A are set in 0-50A, the current is gradually increased according to a set program, and an arc root under any gradient traverses the whole area to be prepared;
4. after arc stabilization is carried out continuously for 60 s under 50A, a zirconia surface layer and a zirconia-zirconia double-phase layer are formed by in-situ oxidation of the cathode.
The cathode of the arc discharge at 50A current was subjected to real-time filter trapping, as shown in fig. 4(a), with the arc ignited between the top anode and the bottom cathode, and the arc length was about 5 mm. The surface of the cathode forms a circular concentrated discharge area, the brightness in the area is uniform, and no local discrete spots exist, which shows that the cathode arcing discharge uniformity is good at the moment. After arcing discharge, as shown in fig. 4(b), the ablation central area of the electrode surface is uniformly concave, annular solidification structures are distributed around the ablation central area, and the diameter of the preparation area of the layered structure is about 6mm, so that the service requirement is met. Meanwhile, the electrode ablation uniformity is good, and no local deep hole exists.
The cross-sectional structure of the heterogeneous layered electrode after laser cladding and arc ablation is observed, and as shown in fig. 5, a zirconia layer, a zirconia-zirconia double-phase layer, a zirconium layer, a copper-niobium transition layer and a pure copper matrix are arranged from the surface to the inside, and the layers are tightly combined. The thickness of the zirconia layer and the double-phase layer is about 120 mu m, and in subsequent actual service, the zirconia layer bears arc roots in a molten state, so that the uniformity of arcing discharge is ensured, and heat generation is reduced by low work function; the zirconium oxide-zirconium dual-phase layer promotes the sustainability of uniform ablation, the pure copper matrix at the bottom conducts the heat input of the consumed arc root in time, the temperature rise of the electrode is controlled, and the service life of the electrode is prolonged under multiple actions.
Comparative example 1:
the electrode prepared in this example was similar in structure to example 1, with a zirconia layer, a zirconia-zirconia bilayer, a zirconium layer, a niobium-copper transition layer and a pure copper matrix facing inward. The arc stabilizing current in the service environment is 52A.
The difference is that when the transition layer is prepared by laser cladding, the adopted power is high, the powder amount is relatively low, and the dilution rate of the transition layer is not strictly controlled. The final transition layer contains about 70-80 at% of copper.
The process for sequentially melting the copper-niobium transition layer and the zirconium layer on the surface of the copper substrate comprises the following steps:
1. will be 200X 100X 10 mm3The pure copper block body is clamped on a sample table of a laser cladding system by 200 multiplied by 100 mm2As a cladding surface, starting a sample table preheating module, and setting the preheating temperature to be 200 ℃ according to the arc stabilizing service current;
2. removing an oxide layer or a deformation layer on the upper surface of the copper block by using a mechanical polishing tool to ensure that the surface to be clad is smooth;
3. filling a proper amount of niobium powder into a No. 1 powder barrel, setting the cladding power to 2250W, the rotating speed of a powder disc to be 0.1 r/s, the moving speed to be 0.06 m/s, the deviation to be 0.2 mm and the working distance to be 15.5 mm, and starting the cladding of a transition layer;
4. after the cladding of the transition layer is finished, filling zirconium powder into a No. 2 powder barrel, adjusting the working distance to 14.5 mm, setting the work to 2000W, the rotating speed of a powder disc to be 0.3 r/s, the moving speed to be 0.045 m/s and the offset to be 0.4 mm. When the surface temperature of the transition layer is reduced to about 250 ℃, removing an oxide layer, slag and the like on the surface of the coating by using a mechanical polishing device, and starting cladding equipment to complete cladding of the zirconium layer;
5. and naturally cooling the sample to room temperature to finish the laser cladding preparation part of the heterogeneous layered electrode.
After the copper-niobium transition layer is prepared by cladding, the cross-section metallographic structure is as shown in fig. 6(a), the thickness of the copper-niobium transition layer is about 550 micrometers, the inside of the layer is in a phase-separated state and is composed of a cyan niobium phase and an orange copper phase, the agglomeration of niobium particles is obviously aggravated compared with that in fig. 2(a), the copper content (to 75 at%) of a coating layer is obviously increased, and the dilution rate is too high. After the zirconium surface layer is secondarily clad on the surface of the copper-niobium transition layer, the cross section metallographic phase of the prepared electrode is as shown in fig. 6(b), and a pure copper-niobium-zirconium layered structure is formed, but the surface of the zirconium layer is severely fluctuated, and the thinnest part is less than 250 micrometers. In addition, the zirconium layer and the niobium layer are not metallurgically bonded locally, the interface is separated, the quality of a layered structure is deteriorated, and the subsequent service stability of the electrode is threatened. The test results of the components and the mechanical properties show that the copper content of the zirconium layer is about 27at percent, and the hardness is 630 HV; the copper content of the copper-niobium transition layer is 77at%, the hardness is 195 HV, and the elongation is 9.1%. Then, taking the layered coating prepared after cladding as a cathode, and carrying out arc discharge in an active atmosphere to prepare a zirconium oxide-zirconium two-phase layer and a zirconium oxide surface layer, wherein the specific process is as follows:
1. and (3) preparing the coating sample into an electrode sample with a specific size by mechanical processing modes such as linear cutting and the like, and soaking the electrode sample in acetone to remove oil stains, oxide scales and the like. Then, polishing the zirconium surface layer by 600-2000-mesh abrasive paper to make the surface smooth;
2. and clamping the polished coating electrode on an ablation test platform to serve as a cathode. Starting an external active gas source of the ablation device for 2 min to fill an arc space with active atmosphere;
3. and setting the surface of the coating to be 4 mm away from the tip of the anode according to the height of the cathode sample, setting the preheating temperature to be 200 ℃, and setting a current increasing program and an arc root motion track according to the arc stabilizing service current. The gradient current increasing program is shown in FIG. 3, five gradients of 10, 20, 30, 40 and 50A are set in 0-50A, the current is gradually increased according to a set program, and the arc root traverses the whole area to be prepared under any gradient;
4. after arc stabilization is carried out continuously for 60 s under 50A, a zirconium oxide-zirconium double-phase layer and a zirconium oxide surface layer are formed by in-situ oxidation of a cathode.
The surface topography of the prepared heterogeneous layered electrode is observed (figure 7), the diameter of the circular concentrated discharge area is about 7 mm, and cracks transversely penetrating through the discharge area appear on the surface. The electrode was observed for cross-sectional structure, as shown in fig. 7(b), and divided into a zirconia layer, a zirconia-zirconia two-phase layer, a zirconium layer, a copper-niobium transition layer and a copper matrix from the surface to the inside, and the discharge surface was internally and longitudinally cracked, and the cracks penetrated through the interface between the zirconium layer and the copper-niobium transition layer, and resulted in the integral peeling of the interface, and the resulting layered structure could not satisfy the uniform and sustainable arcing discharge requirements.
Example 2:
according to the heterogeneous layered electrode structure, the transition layer is a copper-chromium coating or a copper-iron coating, the copper content of the transition layer is strictly controlled to be not higher than 60at%, the hardness of the transition layer is 300-400 HV, meanwhile, the upper surface of the transition layer needs to have certain formability, and the flatness of the surface of the coating after cladding of the zirconium layer is guaranteed.
Starting from a pure copper matrix, and carrying out laser cladding and arc ablation to prepare a heterogeneous layered electrode structure which comprises a zirconium oxide layer, a zirconium oxide-zirconium double-phase layer, a zirconium layer, a chromium/iron-copper transition layer and the pure copper matrix from the surface to the inside. The arc stabilizing current in the actual service environment of the electrode is 32A. The purity of the used chromium powder, iron powder and zirconium powder is higher than 99.5%, and the mesh number is 200-300.
During cladding, the power adjustment range of the laser is 1500-2250W, the working distance is 13-16 mm, and the chromium/iron powder and the zirconium powder are respectively arranged in a powder barrel No. 1 and a powder barrel No. 2 which are independently controllable. The cladding process comprises the following steps:
1. will be 200X 100X 10 mm3The pure copper block body is clamped on a sample table of a laser cladding system by 200 multiplied by 100 mm2As a cladding surface, starting a sample table preheating module, and setting the preheating temperature to be 150 ℃ according to the arc stabilizing service current;
2. removing an oxide layer or a deformation layer on the upper surface of the copper block by using a mechanical polishing tool to ensure that the surface to be clad is smooth;
3. filling a proper amount of chromium powder into a No. 1 powder barrel, setting the cladding power to be 1800W, the rotating speed of a powder disc to be 0.25 r/s, the moving speed to be 0.07 m/s, the deviation to be 0.16 mm and the working distance to be 15.5 mm, and starting a transition layer for cladding;
4. after the cladding of the transition layer is finished, filling zirconium powder into a No. 2 powder barrel, adjusting the working distance to 14.5 mm, setting the power to be 1900W, the rotating speed of a powder disc to be 0.3 r/s, the moving speed to be 0.045 m/s and the offset to be 0.32 mm. When the surface temperature of the transition layer is reduced to about 250 ℃, removing an oxide layer, slag and the like on the surface of the coating by using a mechanical polishing device, and starting cladding equipment to complete cladding of the zirconium layer;
5. and naturally cooling the sample to room temperature to finish the laser cladding preparation part of the heterogeneous layered electrode.
The electrode structure after laser cladding is shown in fig. 9(a), and comprises a zirconium layer, a copper-chromium transition layer and a pure copper matrix, and the layers are metallurgically bonded. The surface of the zirconium layer is in a ridge shape, the average thickness is higher than 500 mu m, and the thickness of the thinnest part is not lower than 488 mu m. The test results of the components and the mechanical properties show that the laminated structure is prepared, the copper content of the zirconium layer is about 8.8at percent, and the hardness is 675 HV; the copper content of the copper-chromium transition layer is 52.5at%, the hardness is 340 HV, and the elongation is 11.2%.
Then taking the prepared layered coating after cladding as a cathode, carrying out arc discharge in an active atmosphere, melting zirconium on the surface of the coating, then reacting with arc plasma, and generating a zirconium oxide-zirconium double-phase layer and a zirconium oxide surface layer in situ, wherein the specific preparation process comprises the following steps:
1. and (3) preparing the coating sample into an electrode sample with a specific size by mechanical processing modes such as linear cutting and the like, and soaking the electrode sample in acetone to remove oil stains, oxide scales and the like. Then, polishing the zirconium surface layer by 600-2000-mesh abrasive paper to make the surface smooth;
2. and clamping the polished coating electrode on an ablation test platform to serve as a cathode. Starting an external active gas source of the ablation device for 2 min to fill an arc space with active atmosphere;
3. and setting the surface of the coating to be 4 mm away from the tip of the anode according to the height of the cathode sample, setting the preheating temperature to be 200 ℃, and setting a current increasing program and an arc root motion track according to the arc stabilizing service current. The gradient current increasing program is shown in FIG. 8, three gradients of 10, 20 and 30 are set in 0-32A, the current is gradually increased according to a set program, and the arc root traverses the whole area to be prepared under any gradient;
4. after arc stabilization is continued for 45 s under 30A, a zirconium oxide-zirconium double-phase layer and a zirconium oxide surface layer are formed by in-situ oxidation of the cathode.
After laser cladding and arc ablation, as shown in fig. 9(b), the heterogeneous layered electrode structure is composed of a zirconia layer, a zirconia-zirconia double-phase layer, a zirconium layer, a transition layer and a pure copper substrate from the surface to the inside, and the layers are tightly combined, so that the heterogeneous layered electrode structure has the characteristic of uniform arcing discharge in an active atmosphere.
Claims (10)
1. A copper-based heterogeneous layered structure electrode with uniform and stable arcing characteristics is characterized in that: the copper-based heterogeneous layered structure electrode at least comprises a zirconia layer, a zirconia-zirconia double-phase layer, a zirconium surface layer, a transition layer and a pure copper matrix from the surface to the inside;
wherein the zirconium oxide-zirconium double-phase layer is formed by the aggregation of zirconium oxide and metal zirconium;
the zirconium surface layer consists of zirconium, a small amount of copper and a small amount of other metals;
the transition layer is a multiphase structure formed by copper and other metals;
wherein the other metal is any one of chromium, niobium or iron;
wherein the zirconia is formed by in-situ oxidation of metal zirconium on a zirconium surface layer.
2. A copper-based heterolaminar structure electrode according to claim 1, characterized in that: the zirconium oxide is formed by in-situ oxidation of metal zirconium on a zirconium surface layer by an arc ablation technology.
3. The copper-based heterolamellar structure electrode according to claim, characterized in that: the zirconium surface layer, the transition layer and the pure copper substrate are in metallurgical bonding, and the interface between the layers is complete and has no transverse crack.
4. The copper-based heterolamellar structure electrode according to claim, characterized in that: the electrode has a uniform arc ablation characteristic that is characterized by: in the process of arc burning and ablation of the electrode, the surface of the electrode presents spherical or ellipsoidal bright spots, the discharge is uniform in the bright spots, and the brightness is uniform without local discrete spots.
5. The copper-based heterolamellar structure electrode according to claim, characterized in that: the transition layer contains 40-60 at% of copper; the copper content of the zirconium surface layer is not higher than 15at%, and the thickness of the zirconium surface layer is not lower than 450 mu m.
6. A method for preparing a copper-based heterolamellar structured electrode according to any of claims 1 to 5, characterized in that: the preparation of the copper-based heterogeneous layered structure electrode is realized by two processes, namely the preparation of a zirconium layer on the surface of a copper matrix and the preparation of an ablation-resistant oxide layer on the surface of zirconium, wherein the preparation of the zirconium layer on the surface of a pure copper matrix adopts a high-speed laser cladding method, and the preparation of the ablation-resistant oxide layer on the surface of zirconium adopts an in-situ arc ablation technology;
preparing a zirconium layer on the surface of the pure copper substrate by using block pure copper and two metal powders as raw materials, wherein one metal powder is zirconium powder, and the other metal powder is any one of chromium, niobium and iron, and preparing a transition layer and a zirconium surface layer in the electrode by using a high-speed laser cladding method to form three coating layers of the pure copper substrate, the transition layer and the zirconium surface layer;
the resistant preparation of sintering of erosion oxide layer of zirconium surface, with the last cladding zirconium top layer that makes is the negative pole in the preparation of pure copper matrix body surface zirconium layer, after arcing discharges under the oxygen atmosphere, normal position reaction zirconia-zirconium diphase layer, zirconia layer.
7. The preparation method of the copper-based heterogeneous layered structure electrode according to claim 6, wherein the preparation process of the zirconium layer on the surface of the pure copper matrix is carried out by a high-speed laser cladding method, and comprises the following steps:
1) placing the block pure copper on a sample table of a high-speed laser cladding platform, and carrying out preheating treatment;
2) after polishing and removing oxide skin or a damaged layer on the surface of the pure copper, putting any one of chromium powder, niobium powder or iron powder and zirconium powder into a powder barrel;
3) setting cladding parameters; starting cladding, and supplying powder to a powder cylinder filled with chromium powder, niobium powder or iron powder to finish the preparation of the transition layer;
4) adjusting cladding parameters, namely reducing the cladding power, reducing the distance between a cladding head and a cladding surface and increasing the offset between roads relative to the cladding parameters in the step 3) to enable the prepared cladding surface to be ridge-shaped; and after the temperature of the cladding surface is cooled, starting cladding, and supplying powder to a powder cylinder filled with zirconium powder to prepare a zirconium surface layer.
8. The method for preparing the copper-based heterogeneous layered structure electrode according to claim 6, wherein the process for preparing the sintered-corrosion-resistant oxide layer on the surface of the zirconium is performed by an in-situ arc ablation technique, and comprises the following steps:
I) placing a sample which is prepared by the zirconium layer on the surface of the pure copper matrix in an arc generating device to be used as a cathode;
II) setting a preheating temperature and a current step increase program of the electric arc generating device; planning a moving path of an arc root on the surface of the cathode, wherein the track is set in a mode that the arc root traverses the preparation area of the electrode with the layered structure under a single current gradient value;
III) starting preheating, introducing an oxidizing atmosphere, starting an electric arc generating device, and puncturing a gas gap between the sample and the anode after the sample reaches a preset preheating temperature, and then, burning and stabilizing the arc;
IIII) continuously arcing after the target current is reached according to a preset current step increase program, so that the preparation of the zirconia layer and the zirconia-zirconia double-phase layer is completed, and the electrode is finally completed.
9. The method for preparing a copper-based heterogeneous layered structure electrode according to claim 8, wherein the current step growth procedure of step II) is set as follows:
10. Use of a copper-based heterolamellar structured electrode according to any of claims 1 to 5, characterized in that: the copper-based heterogeneous layered structure electrode is used as a cathode of an arc discharge device.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01269047A (en) * | 1988-04-20 | 1989-10-26 | Ngk Spark Plug Co Ltd | Production of zirconia sintered body element |
| US6583378B1 (en) * | 1999-11-26 | 2003-06-24 | Komatsu Industries Corporation | Plasma machining electrode and plasma machining device |
| CN101522957A (en) * | 2006-09-28 | 2009-09-02 | 日本帕卡濑精株式会社 | Method for coating ceramic film on metal, electrolysis solution for use in the method, and ceramic film and metal material |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01269047A (en) * | 1988-04-20 | 1989-10-26 | Ngk Spark Plug Co Ltd | Production of zirconia sintered body element |
| US6583378B1 (en) * | 1999-11-26 | 2003-06-24 | Komatsu Industries Corporation | Plasma machining electrode and plasma machining device |
| CN101522957A (en) * | 2006-09-28 | 2009-09-02 | 日本帕卡濑精株式会社 | Method for coating ceramic film on metal, electrolysis solution for use in the method, and ceramic film and metal material |
Cited By (1)
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|---|---|---|---|---|
| CN114040534A (en) * | 2021-11-01 | 2022-02-11 | 浙江大学 | Non-cracking copper-based heterogeneous layered electrode structure and preparation method thereof |
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