CN110653475A - A kind of electrode tip coating and preparation method and application thereof - Google Patents

Abstract

The invention discloses an electrode tip coating and a preparation method and application thereof. The electrode tip coating comprises the following substances in mass percentage: AgCuTi _4.5 35-88 wt %, TiC 10-60 wt % and a silicone resin binder 2 ~5 wt%. The preparation method comprises the following steps: (a) sticking the coating layer on the surface of the pretreated electrode head, and keeping the reaction at 300-350 DEG C for 30-40 minutes; (b) keeping the reaction at 450-550 DEG C for 20-40 minutes 30min; (c) vacuum brazing reaction at 860～930℃ for 10～45min; (d) cooling to 400～500℃, holding for 10～30min, then cooling to room temperature naturally; (e) final cryogenic treatment for 12～ 48h, the coated electrode tip can be prepared. The application is that the electrode tip coating is applied to the preparation of the electrode tip. The invention can effectively improve the wear resistance and hardness of the surface of the base material, at the same time the metal cloth can be cut into various shapes, the ability to adapt to the shape of the electrode head is strong, and the spatial position between the coating and the base can be well controlled.

Description

A kind of electrode tip coating and preparation method and application thereof

technical field

The invention relates to the field of material processing, in particular to an electrode tip coating and a preparation method and application thereof.

Background technique

Due to its good corrosion resistance, galvanized steel sheet has been widely used in automobiles, home appliances, construction and other fields in recent years. The most critical part of the resistance welding machine is the welding electrode joint. When spot welding galvanized steel sheet, the zinc coating with low melting point on the surface reduces the contact resistance and current density. Increasing the welding current or prolonging the welding time further promotes the formation of alloying of the electrode tip. Moreover, frequent contact with the workpiece under high temperature and high pressure accelerates electrode wear. Compared with ordinary steel plate welding (non-coated steel plate), the life of spot welding galvanized steel plate electrodes is generally shorter. Therefore, there is an urgent need for an electrode material that can not only overcome various performance problems in welding, but also reduce the cost of electrode manufacturing.

As early as the 1970s, 0.6-1.0% cadmium (Cd) was added to copper to form a solid solution, and electrode materials with increased hardness through high cold work hardening had electrical conductivity and thermal conductivity not much lower than copper, and the high temperature hardness was higher than that of copper. Copper high. In addition, 0.5-1.0% of chromium (Cr) is added to copper to form an alloy material that can be strengthened by heat treatment. Since chrome-copper is a heat-treated alloy, it has high hardness at high temperature, good durability, and low electrical conductivity and thermal conductivity, so as to obtain electrode materials with high hardness and good electrical conductivity, but it is found that the electrode life when used in the welding of galvanized steel sheets is used. very short.

Later, people conducted trial production of various alloys and found that the electrode materials made by adding a small amount of zirconium to the chromium-copper alloy have greatly improved their various properties, and their lifespan has also been greatly improved compared with the first two electrode materials. The chromium zirconium copper electrode achieves a good balance of the four performance indicators of the welding electrode. However, in the resistance welding of galvanized steel sheet, the Cu-Cr-Zr alloy electrode has two main disadvantages: one is that the electrode will be seriously bonded to the steel plate, which greatly reduces the production efficiency; The service life of the plate and electrode wheel) is significantly shorter than when welding uncoated steel. When welding uncoated steel sheets, the service life of resistance welding electrodes (such as Cu-Cr-Zr alloy electrodes) can usually reach more than 10,000 solder joints, while when welding galvanized steel sheets, the service life of Cu-Cr-Zr alloy electrodes is only a few Hundreds of solder joints. When spot welding galvanized steel sheet with non-cryogenic treatment electrode, the electrode sticking phenomenon is serious, and there is spatter, and the surface color of solder joint is brass. The surface of the spot has a very light brass color, indicating that the copper-zinc alloying tendency is small.

Therefore, the development and production of electrodes with high service life and high wear resistance specially used for resistance welding of galvanized steel sheets has become an urgent problem to be solved. also urgently need to be resolved.

SUMMARY OF THE INVENTION

Purpose of the invention: In order to overcome the deficiencies in the prior art, the purpose of the present invention is to provide an electrode tip coating that improves surface hardness, wear resistance and corrosion resistance. Another purpose of the present invention is to provide a simple and convenient , Safe and environmentally friendly electrode tip coating preparation method, another object of the present invention is to provide an electrode tip coating applied to the preparation of electrode tips, which can improve the wear resistance and hardness of the electrode tip surface.

Technical solution: The electrode tip coating of the present invention contains the following substances by mass percentage: AgCuTi _4.5 35-88wt%, TiC 10-60wt% and silicone resin binder 2-5wt%. It can effectively improve the wear resistance and hardness of the surface of the electrode tip, and enhance the bonding strength between the coating and the electrode tip. Among them, the addition of TiC powder improves the surface hardness, wear resistance and corrosion resistance of the composition; AgCuTi4.5 powder is added as a solder to improve the overall properties of the coating such as fluidity, thickness and structure.

Among them, TiC includes TiC with a particle size of 40-60 nm and TiC with a particle size of 600-800 nm, and the mass ratio of the two is 0.4-0.6:1. Two kinds of TiC powders with different mesh numbers are used, and then the smaller TiC particles are used. It can be filled into the gap between the larger TiC particles and the larger TiC particles to ensure the compactness of the coating. The silicone resin adhesive contains the following substances in mass percentage: 40-50wt% of polytetrafluoroethylene, 12-15wt% of methyltriethoxysilane, 3-5wt% of maleic anhydride, and 5-10wt% of polyacetal resin %, talc 4-6wt%, acrylate rubber 6-8wt%, polycarbonate 4-6wt%, and the balance is hydroxy polydimethylsiloxane.

The preparation method of the above electrode head coating: AgCuTi4.5 powder and TiC powder are mixed according to the mass ratio, then add the silicone resin binder and mix well, then adjust the gap between the rolling roller and the worktable several times, and repeat rolling. to obtain a silver-based coating. The gap between the rolling bar and the worktable is initially 3-5mm, and then adjusted to 2-3.0mm and 0.5-2.0mm in turn, and the rolling time of each gap is 15-30min. When the rollers of the rolling mill are rolled, the positive pressure on the particles exerts an extrusion effect on the binder, and the binder gradually forms into a fibrous shape after multiple extrusions, becoming a criss-cross three-dimensional spider web structure, while the AgCuTi4.5 powder , TiC powder is embedded or wrapped in it, so that the dispersed powder materials are combined into a whole to form a coated metal cloth.

The above-mentioned electrode tip coating is applied to the preparation of the electrode tip, which includes the following steps:

a. Adhere the coating to the surface of the pretreated electrode head, and keep the reaction at 300 to 350°C for 30 to 40 minutes to decompose and volatilize the silicone resin binder. The pretreatment is to grind the surface of the electrode head with sandpaper, and use After cleaning with alcohol, put it into an ultrasonic cleaner, add acetone to clean it, then wipe it with a cleaning cloth and dry it at room temperature;

b. The reaction is kept at 450-550°C for 20-30 minutes, so that a certain degree of vacuum is maintained in the vacuum brazing furnace;

c. Carry out the vacuum brazing reaction at 830-930℃ for 10-45min, the brazing filler metal melts into a liquid state, and the liquid brazing filler metal wets and spreads on the surface of the alloy electrode and interacts with the base metal;

d. Cool to 400-500°C, keep the temperature for 10-30min, and then naturally cool to room temperature to obtain the coated electrode tip.

e. Cryogenic treatment of the electrode head can effectively prolong its service life. Specifically, the electrode is immersed in liquid nitrogen, and the cryogenic treatment time is 12 to 48 hours. After the holding time, the sample is taken out and placed in the air to slowly cool to room temperature.

Wherein, the heating rate in steps a-c is 8-10°C/min. The cooling rate in step d is 3-5°C/min.

Beneficial effect: Compared with the prior art, the present invention has the following remarkable features:

1. The electrode head coating is a flexible fibrous technical material. AgCuTi4.5 powder and TiC powder are compounded, the composition is uniform and dense, and the metal fibers in the coating form a crisscross three-dimensional spider web structure;

2. Combined with Cu-Cr-Zr alloy electrode tip, it not only has excellent matching, melting point, lubricity, and caulking ability, but also has excellent forming effect and high bonding strength, which can effectively improve the wear resistance and hardness of the surface of the matrix material. At the same time, the metal cloth can be cut into various shapes, which has a strong ability to adapt to the shape of the electrode head, and the spatial position between the coating and the substrate can be well controlled;

3. The preparation method of the coating is simple, safe and environmentally friendly;

4. The electrode tip after welding can effectively prolong its service life after cryogenic treatment.

Description of drawings

FIG. 1 is a schematic structural diagram of an electrode tip of the present invention.

Detailed ways

As shown in Figure 1, the electrode tip 1 has an electrode tip coating 2 on the upper end.

Example 1

The raw materials of electrode tip coating 2 include the following raw materials: 35wt% AgCuTi4.5 powder, 60wt% TiC powder and 5wt% silicone resin binder. The silicone resin binder includes the following raw materials: 40% of polytetrafluoroethylene, 15% by weight of methyltriethoxysilane, 3% by weight of maleic anhydride, 10% by weight of polyacetal resin, 4% by weight of talc, and 8% by weight of acrylate rubber %, polycarbonate 4 wt %, hydroxy polydimethylsiloxane 16 wt %. The preparation method of this coating 2 comprises the steps:

(1) Weigh AgCuTi4.5 powder and TiC powder by mass percentage, and mix them;

(2) the mixture is loaded into the automatic stirring equipment vessel, and the silicone resin binder is added, and the vessel is then closed and stirred to obtain a uniform mixture;

(3) rolling the mixed metal powder particles obtained in step (2) in automatic roll equipment, first initially adjusting the distance between the roll and the table, controlling the thickness of the bonding cloth to be about 3.5mm, and carrying out preliminary roll forming for 30min;

(4) Roll the bonding cloth again, adjust the distance between the roll and the table again, control the height to 2.4mm, and repeat the roll 3 times for 30min to produce the adhesive on the surface of the metal particles and between the metal particles. Extrusion, the adhesive forms fibrous under extrusion;

(5) Adjust the distance between the roller and the worktable to the thickness range of the required "metal cloth" (thickness is 0.8mm), repeat the roller for 6 times on the front and back sides for 30min, and the metal fibers form a crisscross three-dimensional The spider web structure, the metal particles are embedded or wrapped in the adhesive, so that the dispersed alloy metal powder forms an interconnected whole, the metal particles in each section of the fiber are evenly distributed, and the roll forms a flexible coating cloth.

The brazing process of the electrode tip coating 2 includes the following steps:

(1) Preparation stage: The brazing equipment adopts WZB-20 vacuum brazing furnace. Before welding, grind the surface of the electrode head 1 with sandpaper, clean it with alcohol, put it into an ultrasonic cleaner, add acetone, clean it for 15 minutes, and then use a cleaning cloth Wipe clean and dry at room temperature; cut a metal cloth suitable for the shape of the electrode tip 1, and stick it to the surface of the electrode tip 1 with brazing glue;

(2) Brazing connection: place the equipped sample in a vacuum brazing furnace as a whole, and set the furnace to a vacuum brazing equipment with a vacuum degree of 1.0×10 ^-4 Pa before welding. Heat up to 350°C at a rate of 10°C/min, hold for 30min, heat up to 450°C at a rate of 10°C/min, hold for 20min, then increase the brazing temperature to 830°C at a rate of 10°C/min, hold for 10min, and then increase the temperature at a rate of 5°C/min The rate of cooling to 450 ℃, holding for 10 minutes, and finally cooling to room temperature with the furnace, take out the welded sample.

The cryogenic treatment process of the electrode tip coating 2 includes the following steps:

The CuCrZr electrode was immersed in liquid nitrogen by the immersion method, and the cryogenic treatment time was 12 h.

Performance testing: Through observation, it can be seen that the coating 2 on the surface of the electrode tip 1 is well formed, forming a dense interface bond, and the multi-point test on the surface of the coating 2 material shows that the hardness is 695HRC, and the life of the electrode tip 1 is 2200 points.

Example 2

The raw materials of electrode tip coating 2 include the following raw materials: 88% AgCuTi4.5 powder, 10% TiC powder and 2% silicone resin binder. The silicone resin binder includes the following raw materials: 50% of polytetrafluoroethylene, 12% of methyltriethoxysilane, 5% of maleic anhydride, 5% of polyacetal resin, 6% of talc, 6% of acrylate rubber %, Polycarbonate 6%, Hydroxy Dimethicone 10%.

The preparation method of the electrode tip coating 2 comprises the following steps:

(1) Weigh AgCuTi4.5 powder and TiC powder by mass percentage, and mix them; (2) put the mixture into the automatic stirring equipment vessel, and add silicone resin binder, then seal the vessel, stir to obtain homogeneous mixture;

(3) rolling the mixed metal powder particles obtained in step (2) in an automatic roll equipment, firstly adjusting the distance between the roll and the workbench, controlling the thickness of the bonding cloth to be about 4.5mm, and carrying out preliminary roll forming for 20min;

(4) Roll the bonding cloth again, adjust the distance between the roller and the worktable again, control the height to 2.8mm, give a positive pressure to the bonding cloth, repeat the rolling twice for 20min, the surface of the metal particles and the metal The binder between the particles produces an extrusion effect, and the binder forms a fibrous shape under the extrusion effect;

(5) Adjust the distance between the roller and the worktable to the thickness range of the required "metal cloth" (thickness is 1.5mm), and repeat the roller for 5 times for 20min on the front and back sides, and the metal fibers form a criss-cross three-dimensional Cobweb structure, the metal particles are embedded or wrapped in the adhesive, so that the dispersed alloy metal powder forms an interconnected whole, the metal particles in each section of the fiber are evenly distributed, and the roll forms a flexible metal cloth.

The brazing process of the electrode tip coating 2 includes the following steps:

(1) Preparation stage: The brazing equipment adopts WZB-20 vacuum brazing furnace. Before welding, grind the surface of the electrode head 1 with sandpaper, clean it with alcohol, put it into an ultrasonic cleaner, add acetone, clean it for 15 minutes, and then use a cleaning cloth Wipe clean and dry at room temperature; cut a metal cloth suitable for the shape of the electrode tip 1, and stick it to the surface of the electrode tip 1 with brazing glue;

(2) Brazing connection: The prepared sample is placed in a vacuum brazing furnace as a whole, and the vacuum degree of the furnace is set to 1.0×10 ^-4 Pa before welding. First, raise the temperature to 350°C at a rate of 10°C/min, hold for 30 minutes, heat up to 550°C at a rate of 10°C/min, hold for 20 minutes, then raise the brazing temperature to 930°C at a rate of 10°C/min, hold for 10 minutes, and then Cool to 500°C at a rate of 5°C/min, hold for 10 minutes, and finally cool to room temperature with the furnace, and then take out the welded sample.

The cryogenic treatment process of the electrode tip coating 2 includes the following steps:

The CuCrZr electrode was immersed in liquid nitrogen by the immersion method, and the cryogenic treatment time was 48h.

Performance testing: Through observation, it can be seen that the coating 2 on the surface of the electrode tip 1 is well formed, forming a dense interface bond, and the multi-point test on the surface of the coating 2 material shows that the hardness is 621HRC, and the life of the electrode tip 1 is 2700 points.

Example 3

The raw materials of the electrode tip coating 2 include the following raw materials: 52% AgCuTi4.5 powder, 45% TiC powder and 3% silicone resin binder. The silicone resin binder includes the following raw materials: polytetrafluoroethylene 45%, methyltriethoxysilane 14%, maleic anhydride 4%, polyacetal resin 7%, talc 5%, acrylate rubber 7% %, polycarbonate 5%, hydroxy dimethicone 13%.

The preparation method of the electrode tip coating 2 comprises the following steps:

(1) Weigh AgCuTi4.5 powder and TiC powder by mass percentage, and mix them;

(2) the mixture is loaded into the automatic stirring equipment vessel, and the silicone resin binder is added, and the vessel is then closed and stirred to obtain a uniform mixture;

(2) the mixture is loaded into the automatic stirring equipment vessel, and the silicone resin binder is added, and the vessel is then closed and stirred to obtain a uniform mixture;

(3) rolling the mixed metal powder particles obtained in step (2) in automatic rolling equipment, initially adjusting the distance between the rolling roll and the table, controlling the thickness of the bonding cloth to be about 4.0 mm, and carrying out preliminary rolling for 15 minutes;

(4) Roll the bonding cloth again, adjust the distance between the roller and the table again, control the height to 2.2mm, give a positive pressure to the bonding cloth, repeat the rolling 3 times for 15 minutes, and the surface of the metal particles and the metal The binder between the particles produces an extrusion effect, and the binder forms a fibrous shape under the extrusion effect;

(5) Adjust the distance between the roll and the worktable to the thickness range of the required "metal cloth" (thickness is 1.6mm), repeat the roll roll for 5 times on both sides of the roll for 15min, and the metal fibers form a criss-cross three-dimensional Cobweb structure, the metal particles are embedded or wrapped in the adhesive, so that the dispersed alloy metal powder forms an interconnected whole, the metal particles in each section of the fiber are evenly distributed, and the roll forms a flexible metal cloth.

The brazing process of the electrode tip coating 2 includes the following steps:

(1) Preparation stage: The brazing equipment adopts WZB-20 vacuum brazing furnace. Before welding, grind the surface of the electrode head l with sandpaper, clean it with alcohol, put it into an ultrasonic cleaner, add acetone, clean it for 15 minutes, and then use a cleaning cloth Wipe clean and dry at room temperature; cut a metal cloth suitable for the shape of the electrode tip 1, and stick it to the surface of the electrode tip 1 with brazing glue;

(2) Brazing connection: The prepared sample is placed in a vacuum brazing furnace as a whole, and the vacuum degree of the furnace is set to 1.0×10 ^-4 Pa before welding. First, raise the temperature to 350°C at a rate of 10°C/min, hold for 30 minutes, heat up to 450°C at a rate of 10°C/min, hold for 20 minutes, then raise the brazing temperature to 880°C at a rate of 10°C/min, hold for 10 minutes, and then Cool to 450°C at a rate of 5°C/min, hold for 10 minutes, and finally cool to room temperature with the furnace, and take out the welded sample.

The cryogenic treatment process of the electrode tip coating 2 includes the following steps:

The CuCrZr electrode was immersed in liquid nitrogen by the immersion method, and the cryogenic treatment time was 30h.

Performance testing: Through observation, it can be seen that the coating 2 on the surface of the electrode tip 1 is well formed, forming a dense interface bond, and the multi-point test on the surface of the coating 2 material shows that the hardness is 701HRC, and the life of the electrode tip 1 is 3300 points.

Example 4

The raw materials of the electrode tip coating 2 include the following raw materials: 66wt% AgCuTi4.5 powder, 30wt% powder and 4wt% silicone resin binder. The silicone resin binder includes the following raw materials: 42wt% of polytetrafluoroethylene, 13wt% of methyltriethoxysilane, 3wt% of maleic anhydride, 6wt% of polyacetal resin, 5wt% of talc, and 7wt% of acrylate rubber %, polycarbonate 5 wt %, hydroxy polydimethylsiloxane 19 wt %.

The preparation method of the electrode tip coating 2 comprises the following steps:

(1) Weigh AgCuTi4.5 powder and TiC powder by mass percentage, and mix them;

(2) the mixture is loaded into the automatic stirring equipment vessel, and the silicone resin binder is added, and the vessel is then closed and stirred to obtain a uniform mixture;

(3) rolling the mixed metal powder particles obtained in step (2) in an automatic roll equipment, initially adjusting the distance between the roll and the table, controlling the thickness of the bonding cloth to be about 3.0mm, and carrying out the preliminary roll forming for 15min;

(4) Roll the bonding cloth again, adjust the distance between the roll and the table again, control the height to 2.0mm, repeat the roll twice for 15min, and the adhesive on the surface of the metal particles and between the metal particles will be produced. Extrusion, the adhesive forms fibrous under extrusion;

(5) Adjust the distance between the roll and the worktable to the required thickness range of "metal cloth" (thickness is 0.5mm), repeat the roll roll for 5 times on both sides of the roll for 15min, and the metal fibers form a crisscross three-dimensional The spider web structure, the metal particles are embedded or wrapped in the adhesive, so that the dispersed alloy metal powder forms an interconnected whole, the metal particles in each section of the fiber are evenly distributed, and the roll forms a flexible coating cloth.

The brazing process of the electrode tip coating 2 includes the following steps:

(1) Preparation stage: The brazing equipment adopts WZB-20 vacuum brazing furnace. Before welding, grind the surface of the electrode head 1 with sandpaper, clean it with alcohol, put it into an ultrasonic cleaner, add acetone, clean it for 15 minutes, and then use a cleaning cloth Wipe clean and dry at room temperature; cut a metal cloth suitable for the shape of the electrode tip 1, and stick it to the surface of the electrode tip 1 with brazing glue;

(2) Brazing connection: place the equipped sample in a vacuum brazing furnace as a whole, and set the furnace to a vacuum brazing equipment with a vacuum degree of 1.0×10 ^-4 Pa before welding. Heat up to 300°C at a rate of 8°C/min, hold for 30min, heat up to 450°C at a rate of 8°C/min, hold for 20min, then raise the brazing temperature to 860°C at a rate of 8°C/min, hold for 10min, and then heat at a rate of 3°C/min The rate of cooling to 400 ℃, holding for 10 minutes, and finally cooling to room temperature with the furnace, take out the welded sample.

The cryogenic treatment process of the electrode tip coating 2 includes the following steps:

The CuCrZr electrode was immersed in liquid nitrogen by the immersion method, and the cryogenic treatment time was 12 h.

Performance testing: Through observation, it can be seen that the coating 2 on the surface of the electrode tip is well formed, forming a dense interface bond, and the multi-point test on the surface of the coating 2 material shows that the hardness is 675HRC, and the life of the electrode tip 1 is 2600 points.

Example 5

The raw materials of electrode tip coating 2 include the following raw materials: 57wt% AgCuTi4.5 powder, 40wt% powder and 3wt% silicone resin binder. The silicone resin binder includes the following raw materials: 50wt% of polytetrafluoroethylene, 12wt% of methyltriethoxysilane, 5wt% of maleic anhydride, 10wt% of polyacetal resin, 6wt% of talc, and 8wt% of acrylate rubber %, polycarbonate 6 wt %, hydroxy dimethicone 3 wt %.

The preparation method of the electrode tip coating 2 comprises the following steps:

(1) Weigh AgCuTi4.5 powder and TiC powder by mass percentage, and mix them;

(2) the mixture is loaded into the automatic stirring equipment vessel, and the silicone resin binder is added, and the vessel is then closed and stirred to obtain a uniform mixture;

(3) rolling the mixed metal powder particles obtained in step (2) in an automatic roll equipment, initially adjusting the distance between the roll and the table, controlling the thickness of the bonding cloth to be about 5.0mm, and carrying out preliminary roll forming for 30min;

(4) Roll the bonding cloth again, adjust the distance between the roll and the table again, control the height to 3.0mm, and repeat the roll 3 times for 30min to produce the adhesive on the surface of the metal particles and between the metal particles. Extrusion, the adhesive forms fibrous under extrusion;

(5) Adjust the distance between the roller and the worktable to the thickness range of the required "metal cloth" (thickness is 2.0mm), repeat the roller for 6 times on the front and back sides for 30min, and the metal fibers form a crisscross three-dimensional The spider web structure, the metal particles are embedded or wrapped in the adhesive, so that the dispersed alloy metal powder forms an interconnected whole, the metal particles in each section of the fiber are evenly distributed, and the roll forms a flexible coating cloth.

The brazing process of the electrode tip coating 2 includes the following steps:

(1) Preparation stage: The brazing equipment adopts WZB-20 vacuum brazing furnace. Before welding, grind the surface of the electrode head 1 with sandpaper, clean it with alcohol, put it into an ultrasonic cleaner, add acetone, clean it for 15 minutes, and then use a cleaning cloth Wipe clean and dry at room temperature; cut a metal cloth suitable for the shape of the electrode tip 1, and stick it to the surface of the electrode tip 1 with brazing glue;

(2) Brazing connection: place the equipped sample in a vacuum brazing furnace as a whole, and set the furnace to a vacuum brazing equipment with a vacuum degree of 1.0×10 ^-4 Pa before welding. Heat up to 350°C at a rate of 10°C/min, hold for 40min, heat up to 550°C at a rate of 10°C/min, hold for 30min, then raise the brazing temperature to 930°C at a rate of 10°C/min, hold for 45min, and then increase the temperature at a rate of 5°C/min The rate is cooled to 500 ℃, and the temperature is kept for 30 minutes. Finally, the furnace is cooled to room temperature, and the welded sample is taken out.

The cryogenic treatment process of the electrode tip coating 2 includes the following steps:

The CuCrZr electrode was immersed in liquid nitrogen by the immersion method, and the cryogenic treatment time was 48h.

Performance testing: Through observation, it can be seen that the coating 2 on the surface of the electrode tip 1 is well formed, forming a dense interface bond, and the multi-point test on the surface of the coating 2 material shows that the hardness is 699HRC, and the life of the electrode tip 1 is 2800 points.

Example 6

The raw materials of the electrode tip coating 2 include the following raw materials: 46wt% AgCuTi4.5 powder, 50wt% powder and 4wt% silicone resin binder. The silicone resin binder includes the following raw materials: 43wt% of polytetrafluoroethylene, 15wt% of methyltriethoxysilane, 3wt% of maleic anhydride, 8wt% of polyacetal resin, 4wt% of talcum powder, 8wt% of acrylate rubber %, polycarbonate 4 wt %, hydroxy polydimethylsiloxane 15 wt %.

The preparation method of the electrode tip coating 2 comprises the following steps:

(1) Weigh AgCuTi4.5 powder and TiC powder by mass percentage, and mix them;

(2) the mixture is loaded into the automatic stirring equipment vessel, and the silicone resin binder is added, and the vessel is then closed and stirred to obtain a uniform mixture;

(3) rolling the mixed metal powder particles obtained in step (2) in automatic rolling equipment, initially adjusting the distance between the rolling roll and the table, controlling the thickness of the bonding cloth to be about 4.0 mm, and carrying out preliminary rolling for 19 minutes;

(4) Roll the bonding cloth again, adjust the distance between the roll and the table again, control the height to 2.8mm, repeat the roll for 3 times for 20min, and produce the adhesive on the surface of the metal particles and between the metal particles. Extrusion, the adhesive forms fibrous under extrusion;

(5) Adjust the distance between the roll and the worktable to the required thickness range of "metal cloth" (thickness is 1.5mm), repeat the roll roll for 5 times on both the front and back sides for 25 minutes, and the metal fibers form a crisscross three-dimensional The spider web structure, the metal particles are embedded or wrapped in the adhesive, so that the dispersed alloy metal powder forms an interconnected whole, the metal particles in each section of the fiber are evenly distributed, and the roll forms a flexible coating cloth.

The brazing process of the electrode tip coating 2 includes the following steps:

(1) Preparation stage: The brazing equipment adopts WZB-20 vacuum brazing furnace. Before welding, grind the surface of the electrode head 1 with sandpaper, clean it with alcohol, put it into an ultrasonic cleaner, add acetone, clean it for 15 minutes, and then use a cleaning cloth Wipe clean and dry at room temperature; cut a metal cloth suitable for the shape of the electrode tip 1, and stick it to the surface of the electrode tip 1 with brazing glue;

(2) Brazing connection: place the prepared sample in a vacuum brazing furnace as a whole, and set the furnace to a vacuum brazing equipment with a vacuum degree of 1.0×10 ^-4 Pa before welding. Heat up to 325°C at a rate of 9°C/min, hold for 35min, heat up to 500°C at a rate of 9°C/min, hold for 25min, then raise the brazing temperature to 900°C at a rate of 9°C/min, hold for 25min, and then increase the temperature at a rate of 4°C/min The rate of cooling to 450 ° C, holding for 20 minutes, and finally cooling to room temperature with the furnace, take out the welded sample.

The cryogenic treatment process of the electrode tip coating 2 includes the following steps:

The CuCrZr electrode was immersed in liquid nitrogen by the immersion method, and the cryogenic treatment time was 30h.

Performance testing: Through observation, it can be seen that the coating 2 on the surface of the electrode tip 1 is well formed, forming a dense interface bond, and the multi-point test on the surface of the coating 2 material shows that the hardness is 683HRC, and the life of the electrode tip 1 is 2500 points.

Comparative Example 1

In Example 1, the CuCrZr electrode was not subjected to the final cryogenic treatment, and the other treatments were the same. The measured hardness was 599 HRC, and the life of the electrode tip 1 was 1100 points.

Claims (10)

1. An electrode head coating, characterized in that it comprises the following substances in mass percent: AgCuTi_4.535-88 wt%, TiC 10-60 wt% and organic silicon resin binder 2-5 wt%.

2. A electrode head coating according to claim 1, wherein: the TiC comprises TiC with the particle size of 40-60 nm and TiC with the particle size of 600-800 nm, and the mass ratio of the TiC to the TiC is 0.4-0.6: 1.

3. An electrode head coating according to claim 1, wherein the silicone resin binder comprises the following mass percentages: 40-50 wt% of polytetrafluoroethylene, 12-15 wt% of methyltriethoxysilane, 3-5 wt% of maleic anhydride, 5-10 wt% of polyaldehyde resin, 4-6 wt% of talcum powder, 6-8 wt% of acrylate rubber, 4-6 wt% of polycarbonate and the balance of hydroxy polydimethylsiloxane.

4. A preparation method of an electrode tip coating is characterized in that: and mixing AgCuTi4.5 powder and TiC powder according to the mass ratio, adding an organic silicon resin binder, uniformly mixing, adjusting the gap between a rolling rod and a workbench for multiple times, and repeatedly rolling to obtain the silver-based coating.

5. A method of preparing a coating for an electrode head as claimed in claim 4, wherein: the gap between the rolling rod and the workbench is initially 3-5 mm, then is sequentially adjusted to be 2-3.0 mm and 0.5-2.0 mm, and the rolling time of each gap is 15-30 min.

6. An electrode tip coating as claimed in any one of claims 1 to 3, applied to the preparation of an electrode tip, characterized by comprising the steps of:

(a) tightly attaching the coating to the surface of the pretreated electrode tip, and carrying out heat preservation reaction at 300-350 ℃ for 30-40 min;

(b) reacting for 20-30 min at the temperature of 450-550 ℃ in a heat preservation manner;

(c) carrying out vacuum brazing reaction at 830-930 ℃ for 10-45 min;

(d) and cooling to 400-500 ℃, preserving the heat for 10-30 min, and naturally cooling to room temperature to obtain the coating electrode tip.

7. An electrode head coating according to claim 6 applied to prepare an electrode head, characterized in that: and further comprising the step of performing subzero treatment on the electrode tip, immersing the electrode into liquid nitrogen, wherein the subzero treatment time is 12-48 h, taking out the sample after the heat preservation time is finished, and slowly cooling the sample to room temperature in air.

8. An electrode head coating according to claim 6 applied to prepare an electrode head, characterized in that: and (b) in the step (a), the surface of the electrode head is ground by abrasive paper, the electrode head is cleaned by alcohol and then placed into an ultrasonic cleaner, acetone is added for cleaning, and then the electrode head is wiped clean by a cleaning cloth and dried at normal temperature.

9. An electrode head coating according to claim 6 applied to prepare an electrode head, characterized in that: the heating rate in the steps (a) - (c) is 8-10 ℃/min.

10. An electrode head coating according to claim 6 applied to prepare an electrode head, characterized in that: the cooling rate in the step (d) is 3-5 ℃/min.

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