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Tongda Cemented Carbide Introduction

2015/12/11      view:

Tongda cemented carbide provides a range of extreme performance products and solutions to meet our customers’  requirements.
About cemented carbide
Cemented carbide is the name on a materials group with a broad use in wear applications. The name “cemented carbides” is describing the µm size carbides (almost always WC) glued together of the metal Co.  However,the cemented carbides are not so much metal, instead the major part of the material consists of carbides, which are ceramic. For example, the most common cemented carbide grades which are used to cutting is 90% WC (hard phase) and 10% Co (binder phase). Another big application is rock drilling, where the most common grade has 94% WC and 6% Co. In the China, the name “cemented carbides” very often is shortened to just “carbides”.
Today, the cemented carbide used has been refined heavily, and the number of grades and companies producing has increased, especially in China. There exist a large number of variations of binder phases, hard phases, contents, WC grain sizes and ways to produce the material. Therefore, great user knowledge is needed to be able to choose correct grade to an application.
Cemented carbide is typically manufactured by mixing WC-powder, Co-powder, and an alcohol, to a mix which is spray dried to form an agglomerated powder. This agglomerate is then pressed to form a green body, which has the correct component shape but twice the volume. This green body is then sintered to remove the alcohol and to melt parts of the Co around the WC grains, and the result is a cemented carbide tool.
The cemented carbide performance is a result of a mixture of hard WC grains and soft binder metal, which result in a material with unique combination of hardness and toughness.
Generally, a cemented carbide grade is described by weight fraction of Co-phase/WC-phase and the average WC grain size. There is a large variation of grades, but some typical grades are described in Table 1. Other, maybe more unknown, applications is balls for ball pens, studs in winter tires and armour-piercing bullets. Cemented carbide is also used for diamond pressing tools!
Table 1. Some typical cemented carbide grades and application areas. 

Advantages with cemented carbide
Unique combination of fracture toughness and hardness
Exceptional material substrate to be coated
Very heat resistant (allows high cutting speeds)
Very wear resistant material
Disadvantages with cemented carbide
Requires pressing and sintering, important that the user understands the material.
The properties of cemented carbide cannot be change after production, when it cannot be hardened and re-hardened as steel could be.
Very high cost, since the largest W-mines are in China.
The corrosion resistance is low for low and high pH. In acidic environments, the Co is dissolved and in alkaline environments, the WC is dissolved. 
Tongda cemented carbide products with advantages including exceptional wear resistance, long tool life, consistent performance, high quality finishing and a wide range of options and custom solutions.