F4 Electrodes for Plasma Spraying Gun

• Customization: Available
• Type: Plasma Spray Electrode
• Cooling System: Nature Cooling
• Model NO.: F4 electrode
• Function: Plasma Generated Body
• Materials: Copper and Tungsten
• Apply in: Plasma Spray Coating Industry
• Making Method: Back-Casting
• Style: Standard
• Internal Diameter: 5mm, 6mm, 7mm, 8mm
• Certificate: RoHS, ISO
• Composition: Tungsten, Copper
• Name: F4 Electrodes
• Name 2: Electrode F4
• Name 3: Electrode of F4
• Name 4: Cathode of F4
• Transport Package: Carton
• Specification: 39*21*29cm
• Trademark: WL
• Origin: China
• HS Code: 8515900090
• Production Capacity: 20000PCS/Per Month
• Package Size: 10.00cm * 10.00cm * 10.00cm
• Package Gross Weight: 1.000kg
• Lead Time: 3 days (1 - 10 Pieces) ; To be negotiated ( > 10 Pieces)

Product Description

Product Description

The F4 electrode is a critical consumable component located within the cathode assembly of the widely used Oerlikon Metco F4 (and its variants like F4MB, F4NX) DC plasma spray gun. It plays a fundamental role in generating the plasma arc.

Here are its key characteristics and functions:

1. Function: F4 Cathode (Negative Terminal): The electrode serves as the cathode (negative terminal) in the plasma circuit. Its primary function is to emit electrons necessary to initiate and sustain the plasma arc that ionizes the plasma gas (typically argon, hydrogen, nitrogen, or mixtures).
2. Material: Thoriated Tungsten: The electrode tip is almost exclusively made from tungsten doped with thorium oxide (ThO2), commonly referred to as 2% Thoriated Tungsten. This material is chosen for its exceptional properties:
   • High Melting Point: Essential for withstanding the extreme temperatures at the arc attachment point (>3000°C).
   • High Electron Emission: Thorium oxide significantly lowers the work function of tungsten, making it much easier for electrons to be emitted from the surface (thermionic emission). This results in a more stable arc at lower voltages and currents compared to pure tungsten.
   • Erosion Resistance: While it erodes over time, thoriated tungsten offers good resistance to the intense heat and ion bombardment at the cathode spot.
3. Structure:
   • Tip: The critical front-end part is typically conical or slightly rounded. This is where the high-current-density arc attaches locally ("cathode spot") and electron emission occurs. This tip undergoes the most erosion.
   • Body: The rear section is usually cylindrical and acts as the electrical conductor and thermal path. It's often made of copper or a copper alloy for excellent electrical and thermal conductivity.
   • Assembly: The thoriated tungsten tip is often inserted or brazed into a copper (or copper alloy) holder. This construction leverages the high conductivity of copper for cooling and current conduction, combined with the superior emission and erosion properties of tungsten at the hot tip. Some designs may use a solid thoriated tungsten rod.
4. Operation & Electron Emission:
   • When high voltage is applied between the electrode (cathode) and the nozzle (anode), a pilot arc is initiated (often via high frequency).
   • High current flows through the electrode.
   • Due to its electrical resistance and the intense plasma gas heating, the tip heats to very high temperatures (white-hot).
   • At these temperatures, electrons are readily "boiled off" the thoriated tungsten surface via thermionic emission. These emitted electrons accelerate towards the anode (nozzle), colliding with and ionizing the plasma gas atoms along the way, creating the plasma jet.
5. Location: It sits concentrically within the front cap assembly, surrounded by the plasma gas swirl ring. A small gap exists between the electrode tip and the constricting nozzle bore (anode).
6. Key Parameter - Diameter: Electrodes come in different standard diameters (e.g., 8mm, 10mm) to match the gun's power capabilities. Larger diameters handle higher currents more effectively.
7. Lifespan & Failure Mode: The electrode is a consumable part. Its tip erodes over time due to:
   • High-temperature vaporization/sublimation.
   • Sputtering from ion bombardment.
   • Localized melting if conditions are too severe (e.g., incorrect gas, excessive current).
   • Gradual erosion causes the arc attachment point to move slightly and eventually leads to unstable spraying conditions (fluctuating voltage, erratic plasma). Catastrophic failure (melting, cracking) can occur if operational limits are exceeded or cooling fails.
8. Factors Affecting Life:
   • Plasma Gas Composition: Hydrogen is particularly erosive to the cathode.
   • Current Level: Higher currents increase erosion.
   • Arc Starts: Frequent starts can accelerate tip degradation.
   • Gas Flow Rates/Purity: Insufficient cooling flow or contaminated gas reduces life.
   • Cooling Efficiency: Poor cooling directly shortens electrode life.
   • Electrode Material Quality/Manufacturing.
9. Maintenance: Regular inspection and replacement of the electrode (often alongside the nozzle and sometimes gas injector/swirl ring) are essential for consistent spray performance and coating quality. Signs of wear include excessive erosion, localized melting, or cracking.

In Summary:

The F4 electrode, primarily made of thoriated tungsten, acts as the critical cathode. Its job is to efficiently emit electrons through thermionic emission when heated by the arc current, enabling the creation of the high-temperature plasma jet. Its specialized material and design balance electron emission capability with resistance to extreme heat and erosion, but it inevitably wears out and requires regular replacement as part of routine plasma spray gun maintenance.

Plasma thermal spray gun consumables
    As we all know, the most critical components of plasma thermal spray guns such as F4, F1, 9MB, 7MB, 3M7, SG-100,SinplexPro,TriplexPro and so on are the nozzle and electrode . These two products are also consumable parts and are one of the most important consumables in plasma thermal spraying.
    Our company is a manufacturer specializing in the production of plasma spray electrodes and nozzles (also known as plasma cathodes and anodes, tungsten copper cathodes, and tungsten copper anodes).

High performance F4 plasma nozzle and electrode
In the plasma spraying process, metal or ceramic powder is melted in a plasma arc and then sprayed at high speed onto the workpiece to be coated. In this way, water-impermeable, highly adhesive coatings can be deposited on tools and various equipment components. When used in spray guns, our electrodes must be able to withstand transient plasma temperatures in excess of 12,000°C. This kind of instantaneous high temperature and pressure is not a problem for our F4 electrode. Our company uses back-casting production technology to form a seamless connection between tungsten and copper, which is extremely strong. Therefore, our electrodes can provide stable working conditions for a long time and extend their service life.
Different from the brazing method, brazing uses solder as an intermediate medium to fuse the two alloys, but it is difficult to achieve 100% connection. Therefore, the product produced in this way is first of all not strong enough and is not suitable for the extreme conditions faced in the gun body. High pressure and high temperature can easily cause uneven heat conduction and cracks.

The corresponding list of the nozzle electrode model of our company's F4 and the model of other brand products
 

Product model	Product name	Related product model
WLE-F4	F4 electrode	1072006
WLN-F4-5	F4 nozzle	1088066
WLN-F4-6	F4 nozzle	1072007
WLN-F4-7	F4 nozzle	1088062
WLN-F4-8	F4 nozzle	1088057

There are many F4 electrode manufacturers on the market, but many of them can only make similar sizes, but there are many differences in service life and performance. As a professional manufacturer, we not only know how to produce, but also how to improve and understand customer's use, so we can provide more professional online services.

If you have any needs, users are welcome to come for consultation. Our company has a group of experienced technical and sales teams who will serve you wholeheartedly.

 

Certifications

Packaging & Shipping

You can choose cartons or plywood case:(Our packing)


All goods will be shipped by DHL or UPS or Fedex or SF as well as air freight agent company,you can choose any one only you like.



 

Company Profile

         Zhuzhou Weilai New Materials Technology Co., Ltd (Weilai) is located in China Power Valley in Zhuzhou City of Hunan province. Weilai devotes to research and develop high performance  heterogeneous refractory metal composites, including high-performance X-ray tube anode material, plasma spray nozzle as well as the electrodes and the resistance welding electrodes, etc. It is mainly used in medical equipment, plasma spray and automobile electrical equipment industries. Weilai provides the customized solutions for customers, it is a high-tech company integrating research and development, production, sales and service.

    Adhering to "Keep improving products and creating value for customers", the company focuses on the subdivided fields of refractory metal materials industry, continuously optimizes the technological adaptability of products, develops more supporting products in the industry, and provides users with more reasonable and comprehensive solutions. Weilai makes constant efforts to "become an excellent company in the field of new materials".

Our Advantages

Advantages of plasma spray nozzles and electrodes produced by our company:
1. Our company has been engaged in the production of pure tungsten and tungsten alloy materials for many years, and has an in-depth understanding of the structure and properties of materials. For the tungsten electrode used in plasma spraying electrodes, based on our full understanding of the application, we have made more improvements and treatments to the material structure to meet the material requirements of plasma spraying. By densifying the tungsten electrode, a finer, more uniform grain structure is formed. The modified tungsten alloy has relatively high hardness and density, fast arc starting, excellent resistance to arc burning loss, and long life.

2. Our company's plasma spraying electrodes and nozzles use unique back-casting technology to achieve seamless bonding between tungsten and copper. The bonding strength can be as high as 127MPa, while the traditional bonding strength is less than 100MPa. Compared with traditional brazing, joints made by back-casting have higher bonding strength between tungsten and copper, larger contact area, more uniform resistance, and stronger heat dissipation ability, making the nozzle and electrode more stable and more durable as well as long service life.

3. We produce tungsten electrodes of different materials (good arc starting performance and ablation resistance). Based on customer usage conditions, we can provide more suitable materials for customers to choose.
 

Material	Impurity content (%)	Electron work function (eV)
Lanthanum tungsten	<0.2	2.8-3.2
Cerium tungsten	<0.2	2.7-2.8
Thorium tungsten	<0.2	2.0-3.9

4. Based on the research and analysis of plasma spray guns, the electrodes and nozzles produced by our company can perfectly adapt to the original spray guns, and no additional adjustment of spraying parameters is required during replacement. We have a complete product series, and the plasma spray electrodes and nozzles we produce can be widely used in F4, 9M, SG-100 and other spray guns of Metco, GTV, FST, AMT AG, Praxair and other companies.
5. We have rich experience in producing various cathodes and anodes, which can be customized and processed according to customer samples or drawings. We can also provide semi-finished products with seamless combination of tungsten and copper.

After Sales Service

 

We can ensure our all products which are seamless bonding,no gas foam generating,and assure concentricity,if any defect has been found which are due to our cause,we can replace them for free and send you along with shipment for next time.