Hardmetals coatings

Figure 18 CVD multilayer coating on WC-Co hardmetal with TiNi j as top and bottom layer...

The machining industry is the best example. The dominant tool material today is the coated hardmetal which, in combination with indexable insert technology, has had an enormous impact on the machining industry since its introduction in the late 1960s [9.3]. 

Economic importance. About 23,000 tons/year of hardmetal are currently used in the western world, which correspond to more than 60% of tungsten demand [9.1]. The world market volume for hardmetal cutting tools in 1995 was estimated to be roughly 9 billion DM [9.10]. The price ofhardmetals, on average, equals that of silver. For special tools, like coated indexable inserts, the price is about double that of silver [9.11]. 

Coating became one of the most significant developments in the history of hardmetals which started in the early 1960s and is still imderway today. 

Coated hardmetal is the dominant tool material for indexable inserts and will remain so in the foreseeable future. More than 80% of all turning inserts and about 70% of milling... 

FIGURE 9.27. Cobalt-enriched hardmetal substrate, obtained by gradient sintering with CVD multilayer coating. Outer layer TiCN/TiN middle layen AI2O3 inner layer TiC/TiCN. By courtesy of Kennametal Inc., USA. 

The quality palette of larger producers comprises up to 50-60 hardmetal grades and 8-10 different types of coatings. 

Transition metal carbide, nitride and carbonitride layers of the IVB group made by CVD (chemical vapor deposition) and PVD (physical vapor deposition) are produced in order to increase the service life of hardmetal tools [18,21,108] for cutting and milling operations. About 90% of cutting tools are coated. 

Figure 29. Microstructure of a multilayer-coated steel-turning hardmetal (WIDIA TNI50), with various TiN/Al203 sublayers a TiN and a Ti(C, N) layer.

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