H.C. Starck, of Goslar, Germany, has introduced a new hardmetal (cemented carbide) binder material designated AMPERSINT® MAP which is based on iron and is said to be a cheaper alternative to the cobalt binder normally used. The company states that in addition to being cheaper the new binder has greater corrosion resistance, provides the equivalent or even improved properties to cobalt binders and reduces health risks associated with combination of the tungsten carbide and cobalt. A further plus point for the use of the iron-based binder is that, unlike cobalt, iron is not subject to the same price volatility, although in specific hardmetal compositions the binder can also contain certain quantities of cobalt depending on the required material properties and process characteristics.

Results for 10.4% AMPERSINT® MAP binder M1800 (Fe+0.3%Cr3C2C, C2C+0.1%VC) which is equivalent in volume to 12% cobalt, showed hardness levels of 1566 kg/mm2 (compared with 1391 kg/mm2 for Co binder), and toughness of 13.2 MPa m½ which compares with 12.3 MPa m½ for cobalt. 

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