Cemented carbide, also known as tungsten carbide cobalt or Widia, is a hard metal used for high-speed machining and high-temperature applications. It is made by sintering tungsten carbide particles with cobalt or tantalum carbide and nickel metal. Its weaknesses are brittleness and high production costs, but it can be reinforced with coatings. The material was first developed in the late 1800s by Henri Moissan and commercial use began in Germany in the late 1920s with the brand Widia.
Cemented carbide is a particularly hard metal that is known for being able to handle hard materials, high machine speeds, and high temperatures. The material is also known as harmetal, Widia or tungsten carbide cobalt. It is often used in the production of items such as stainless steel or carbon steel.
Modern cemented carbide is usually a combination of tungsten carbide particles and cobalt metal or tantalum carbide and nickel metal with cobalt. These materials are bonded together in a process known as sintering or, less commonly, hot isostatic pressing (HIP), in which molten cobalt is mixed with solid grains of tungsten carbide. The strength and shelf life of the final product can vary widely, depending on the amount of each ingredient in the blend.
Two of the most obvious weaknesses of cemented carbide are its inherent brittleness and the high expense of producing the material. While cobalt provides increased durability, tools made from this material are still prone to cracking or chipping. Often a stronger metal, such as carbon tool steel, is used as the shank into which a carbide tip can be inserted. This can reduce costs by both reducing the total manufacturing cost of the tool and the cost of replacing the carbide part.
Cemented carbide inserts can also be reinforced with special coatings, such as titanium carbide nitride, titanium aluminum nitride, or diamond-like carbon. These coatings can help increase tool lubrication. The coating can also extend the life of an insert by reducing the temperature during cutting and thus reducing wear.
The first carbide was developed in the late 1800s by Henri Moissan, a French chemist. Moissan had set out to create diamonds, but his experiments led to the development of a porous and brittle version of modern tungsten carbide. The Germans Karl Schroeter and Heinrich Baumhauef discovered that the material could be made stronger and more suitable for industrial uses, such as cutting, by adding cobalt.
Commercial use of cemented carbide began in Germany in the late 1920s. The pioneering brand was Widia, which is a version of wie diament, a German phrase meaning “like diamond”. This brand has endured as a kind of generic term for cemented carbide.
In the 1930s the replacement of tungsten carbide with a bonded blend of tantalum carbide and metallic nickel helped create a more durable form of cemented carbide. Now the material is made with different variations of traditional and modern blends. The one constant has been that the mixture typically consists of one part molten material bonded with grains of another element.
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