Tungsten carbide alloy coating
What is Tungsten Carbide?
Tungsten carbide is a compound of tungsten and carbon, renowned in the industry for its exceptional durability and high melting point (2,870◦C). It is widely used in applications requiring exceptional wear or impact resistance, such as abrasives, knives, dies, and punches.
Tungsten itself is a dense, light grey metal with a melting point of 3,422◦C and is extremely corrosion resistant. Its hardness is similar to that of hardened steel or jade (7.5 on the Mohs scale), that is, soft enough to be cut with a hacksaw. Tungsten is also fairly ductile and can be extruded into filaments; for this reason, most incandescent light bulbs use tungsten as the filament. It is also used in professional welding applications and medical devices.
When tungsten is alloyed with carbon, it can reach a hardness of 9.0 on the Mohs scale, just below diamond. This scratch resistance can be used to make wear-resistant parts such as saw or drill tips, equipment used to make bricks and roof tiles, or in crushing machinery. Its durability also makes it ideal for parts required by the oil and gas industry in harsh subsea environments.
Tungsten carbide has the chemical symbol WC, but may be referred to in industry simply as carbide (although other similar compounds also go by that name, notably titanium carbide and tantalum carbide). In its natural state, it is a fine grey powder that can be sintered (compacted using heat or pressure) onto a surface or bonded (combined with a metal to form a solid).
Tungsten carbide is available in different grades, depending on the binder used – usually cobalt or nickel. Other carbides may be added to improve specific properties, especially density, hardness or transverse rupture strength.
Tungsten Carbide (WC) is an extremely hard ceramic material that comes in the form of fine grey powder particles. Due to its high hardness, this material has excellent resistance to wear, abrasion and scratching. It protects surfaces from damage and other surface attacks such as corrosion, erosion and fatigue. WC is ceramic in nature and is very stable due to its high melting point.
Selection Criteria
The cost of a coating depends directly on the coating material. In this regard, tungsten carbide coating is a premium coating. These coatings are often preferred when parts have suffered irreversible damage due to wear or corrosion, and coating is more cost-effective than buying new ones. In this case, WC coating is a cheaper and viable solution.
Tungsten Carbide Coating Process
Tungsten carbide coating is achieved through the HVOF thermal spray process. In this process, fuel gas and oxygen are burned in a high-pressure chamber at temperatures up to 5,600°F (3,093°C). The resulting high-temperature, high-pressure gas is ejected through a small diameter nozzle and accelerated down a long barrel at supersonic speeds. Tungsten carbide powder (or another powder coating material required for the project) is injected into the nozzle and the particles mix with the high-velocity gas at speeds up to 3,000 feet per second.
Characteristics of tungsten carbide alloy coating
* High hardness
*Good strength
*Excellent resistance to wear, abrasion and scratching
*Good corrosion resistance
*High bonding strength
* Low porosity
*Dense coating
The coating can also achieve a mirror effect or even what the industry calls a ” super mirror ” effect through fine post-processing . This mirror coating is the best choice for achieving rent reduction, sealing, and wear resistance.
Potential Benefits
*Tungsten carbide coating can extend the life of the product .
*Coating technology is efficient and reliable.
*Resists a variety of surface damage.
* It has a good combination of mechanical and metallurgical properties.
Tungsten Carbide Coating Uses and Applications
1. WC coating is mainly used to treat severely worn and damaged surfaces. WC coating is the first choice in areas where the cost of disassembly and replacement of parts is high.
2. These coatings are suitable for machinery where parts are exposed to extreme wear conditions.
3. WC can also be used for abrasive sandpaper, polishing paper, cutting and processing tools.
4. They are also used in the entire metal production process from ore mining to processing into metal, especially in steel production.
5. They are also used in the paper industry to give the surface rolls a good gripping surface.
6. WC coatings are also suitable where a specific surface finish is required. This is because the surface parameters can be achieved through different thermal spraying techniques.
7. These coatings are also used in the power generation sector to protect the fuel source from erosion due to excessive wear in the production chamber.
