Tribological applications of amorphous carbon and crystalline diamond coatings

New machining as well as material developments increase the tribological requirements on components and tools for future applications and products. To meet these requirements, amorphous diamond-like carbon (DLC) and crystalline diamond coatings have been developed and are now entering the market. DLC coatings are deposited with different physical vapor deposition techniques on industrial scale. They show high wear resistance and low friction coefficients. Modification of these coatings is achieved by incorporation of additional elements during growth, leading to the varation of properties like surface energy, temperature stability, wear resistance and friction. These modifications are used to optimize amorphous carbon coatings for different applications. This will be demonstrated for driving elements, motor components and forming tools. Grystalline diamond coatings prepared by activated chemical vapor deposition (CVD) exhibit extreme wear resistance. Prototypes of CVD diamond tools prepared with a large scale hot-filament activation process are successfully used for high speed dry cutting of aluminium silicon alloys, for precision grinding of ceramics and midro machining of silicon and glass. Despite there are still problems with deposition and adhesion of diamond especially on cemented carbide tools, CVD diamond tools for special machining operations like graphite and green compact cutting are on the market.