What material is tungsten carbide?
Tungsten carbide is the name used for a broad class of alloys consisting of actual tungsten carbide and a metal binder with other added carbides (i.e. TiC and TaC). The two most common metal binders are cobalt and nickel. Metallic adhesives affect hardness, toughness, and chemical compatibility. Depending on the properties required, the metal binder content may vary between 3-20% of the finished material.
Tungsten carbide is a very versatile material that can be alloyed to achieve a variety of properties. Its extraordinary hardness can be used to shape and cut almost any other material, and its high temperature resistance allows it to work at high speeds, maximizing its value as a cutting tool.
For this reason, it is increasingly used for work, in addition to typical materials of very high hardness, in various steel alloys, from the most conventional to, due to their properties, the most corrosion-resistant materials. For example manganese steel or tool steel.
Another application of using tungsten carbide due to its reduced ductility and high mechanical resistance is in the coating of components that are subject to continuous friction and must have high wear resistance, such as bearings or rotating elements, where it is applied using thermal projection Coating form of systems (e.g. HVOF).
As one of the hardest materials, tungsten carbide has a hardness between 8.5 and 9.5 on the Mohs scale, surpassed only by a few materials such as diamond. This material is born from the combination between carbon and tungsten, mixed with a small amount of cobalt, and sintered to form one of the so-called CERMET (CERamic METal), which is considered to be one of the most durable and durable compounds in the industry.
Tungsten carbide is made of metal powder sintered under 1,000 atmospheres of pressure. Cobalt powder is used as a binder, and the hardness of cobalt is also very high. Tungsten carbide has extremely high hardness and is usually made into cutting tools that can cut stainless steel, drill bits or armor-piercing bullet cores. Its Vickers hardness can reach up to 1800 HV, making it the hardest material at the time. The hardness of tungsten carbide is basically the same as sapphire.
Tungsten carbide brings real hardness. Unlike the high hardness brought by titanium alloy or other metals through surface hardening technology, tungsten carbide has the same hardness inside and outside. And due to its ultra-high hardness, the brightness after polishing is outstanding.
Tungsten carbide is used in many industries due to its excellent hardness properties compared to tool steels and excellent toughness compared to technical ceramics. Given these excellent properties, tungsten carbide is most often associated with tools used in metal cutting applications such as sawing, milling, and turning. Many people are surprised to learn that tungsten carbide is also often used in fluid distribution or flow applications because of its excellent service life when exposed to aggressive wear. The improved wear resistance of tungsten carbide can extend the life of components such as nozzles in industries such as waterjet cutting, oil and gas, and electronics.
1. Improve material hardness and wear resistance. Spraying tungsten carbide can form a hard and wear-resistant coating. The hardness of this coating is usually 2-3 times higher than the hardness of the raw material, which can greatly improve the wear resistance of the material.
2. Extend the service life of materials. Since spraying tungsten carbide coating can protect the base material from wear and corrosion, it can extend the service life of the material and reduce the frequency and cost of equipment replacement and maintenance.
3. No special pretreatment is required. Compared with other surface treatment technologies, spraying tungsten carbide does not require any special surface treatment. It can directly spray the metal surface, eliminating tedious processing work and shortening the manufacturing cycle.
1. Insufficient bonding force between layers is prone to occur. Since spraying tungsten carbide is to spray paint on the surface of the substrate to form a coating, the insufficient bonding force between the coating and the substrate is prone to peeling or cracking.
2. Affect surface quality. Spraying tungsten carbide is done by spraying. It is difficult to avoid surface defects such as burrs and roughness when forming a coating on the surface. Moreover, the thickness of the coating is inconsistent, which will affect the appearance and quality of the surface.
3. Susceptible to environmental factors such as temperature and humidity. The tiny gaps between the tungsten carbide particles in the coating and the coating matrix will affect the performance of the coating. When encountering changes in environmental factors such as temperature and humidity, it can easily lead to problems such as loosening and peeling of the coating.
To sum up, spraying tungsten carbide is a surface coating technology that can improve the hardness and wear resistance of materials and has certain advantages and disadvantages. When adopting this technology, it needs to be evaluated and selected based on the specific use environment and requirements.
1. Shearing processing
The thickness of tungsten carbide coatings usually ranges from a few microns to tens of microns, so it can be processed by shearing. When shearing, it is necessary to use high-hardness cutting tools, and the processing speed should be controlled within an appropriate range to avoid cutting quality deterioration due to being too fast or too slow.
2. Grinding processing
Tungsten carbide coatings can also be processed by grinding. When grinding, it is necessary to use high-hardness abrasives, such as diamond abrasives, silicon carbide abrasives, etc., to ensure the grinding effect of the coating. When grinding, it is necessary to control the processing parameters, such as grinding speed, grinding depth, grinding pressure, etc., to avoid coating damage caused by excessive grinding.
3. Spark-erosion machining
Tungsten carbide coatings are hard and difficult to machine with traditional cutting and grinding methods, so they can be machined using electrical discharge machining. Electrical discharge machining is to place electrodes on the coating surface and generate high-temperature and high-pressure arcs through discharge to process the coating. During EDM, factors such as electrode shape and discharge parameters need to be controlled to obtain the best processing effect.
4. Chemical processing
Tungsten carbide coatings can also be processed by chemical processing. Chemical processing is to place the coating in a chemical reaction solution and dissolve part of the coating material through the reaction to achieve the processing effect. Chemical processing has the advantages of high processing precision and fast processing speed.
precautions
Before cutting, you should fully understand the physical and chemical properties of tungsten carbide and use appropriate cutting processes and equipment.
When cutting tungsten carbide, you need to choose a suitable diamond cutting tool to ensure that the thin edge of the tool is sharp and the cutting edge is flat.
Adequate safety measures must be taken when cutting tungsten carbide, and safe operating procedures must not be violated.
Sufficient coolant and cooling water are required when cutting tungsten carbide to prevent the material from overheating and causing poor cutting conditions.
During the operation, the cutting speed and cutting depth must be adjusted in a timely manner according to the actual situation, and reasonable cutting processing must be performed according to the cutting material.