Cutting carbonitrides

Molybdenum carbide is also used in TiC—Ni-based alloys and in titanium carbonitride-based cermets for metal-cutting appHcations. 

Garbonitrides. Use of carbonitrides in metal cutting tools, both Ti(C,N) coatings (18) and Ni—Mo cemented carbonitrides (19), is expected to increase in the 1990s. 

Sintered cutting tips or inserts containing c-BN can be brazed to a cemented carbide or other substrates. Brazing bond strength is increased by interlayers of various carbides, nitrides, or carbonitrides [268],... 

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. 

Zr(C, N) layers together with a variety of other layers were successfully introduced for cutting tools for turning steel. A microstructure of such a multilayer is shown in Fig. 30 where Zr(C, N) represents a thick top layer. The favorable performance of such Zr(C, N) containing layers stems for the thermal expansion behavior of Zr(C, N), which is the lowest amongst the group iv carbonitrides, and which reduces tensile stress upon thermal load. Such a behavior enhances the performance of the coatings because of increased crack resistance and adhesion. 

Most of the developments in cemented borides aim at the high wear resistance due to the superior hardness compared to carbide-based hard metals. One of the most important applications are, therefore, the cutting tools where cemented boride have to compete with tungsten carbide, titanium carbonitride, and ceramic materials as well. 

Porat R, Ber A (1990) New approach of cutting tool materials CERMET (Titanium carbonitride-based material) for machining steels. Aim CIRP 39( 1 ) 71-75 Schulz H, Moriwaki T (1992) High-speed machining. CIRP Ann 41(2) 511-537... 

H.Pastor, Titanium-carbonitride-based hard alloy for cutting tools. Mat. Sci. Eng. AlOS/106 401(1988). 

Mixed ceramics are available where the addition of cubic carbides or carbonitrides improves toughness and thermal conductivity. Whisker-reinforced ceramics use silicon carbide whiskers to dramatically increase toughness and enable the use of a cutting fluid. 

Cubic BN composite materials with TiC, TiN, AI2O3, AIN, Si3N4, WC, etc. are also produced. The mechanical properties of these materials depend on their microstructure such as grain size distribution and voids in the composites (258). Because these composite compacts are useful as cutting tools, they are usually described in the patent literature. Some reported elements for these composites are listed in Table 10 (7). A BN material is sintered with these elements and/or their nitrides, carbides, borides, and carbonitrides. Sintering of carbon precoated cBN grains and formation of BxCyNz grain boundaries were claimed in a patent, as quoted in Ref. 7. 

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