The metal tungsten, whose name is derived from Swedish – tung(heavy) and sten (stone) is mainly used in the form of cemented tungsten carbides. Cemented carbides or hard metals as they are often dubbed are a class of materials made by ‘cementing’ grains of tungsten carbide in a binder matrix of the metal cobalt by a process called liquid phase sintering.
Today tungsten carbide grains sizes vary from 0.5 microns to more than 5 micron with a cobalt content that can go up to around 30% by weight. In addition, adding other carbides can also vary the final properties.
The result is a class of materials that are characterized by
High strength
Toughness
High hardness
By varying the grain size of the tungsten carbide and the cobalt content in the matrix, and adding other materials, engineers have access to a class of materials whose properties can be tailored to a variety of engineering applications. This includes high tech tools, wear parts and tools for the construction mining and oil and gas sector.
Tungsten Carbide products are the result of a powder metallurgy process which primarily uses tungsten carbide and cobalt metal powders. Typically, compositions of mixes will range from 4% cobalt to 30% cobalt.
The chief reason for choosing to use tungsten carbide is to take advantage of the high hardness which these materials exhibit thus retarding the wear rate of individual components. Unfortunately, the penalty attached to high hardness is a lack of toughness or strength. Fortunately, by choosing compositions with higher cobalt contents, strength can be achieved alongside hardness.
Choose low cobalt content for applications where the component will not be expected to experience impact, achieve high hardness, high wear resistance.
Choose high cobalt content if the application involves shock or impact and achieve greater wear resistance than most other materials can offer, combined with the ability to resist damage.
Post time: Jul-29-2022