Diamond-like carbon (DLC) is a metastable form of amorphous carbon with significant sp3 bonding. DLC is a semiconductor with a high mechanical hardness, chemical inertness, and optical transparency. This review will describe the deposition methods, deposition mechanisms, characterisation methods, electronic structure, gap states, defects, doping, luminescence, field emission, mechanical properties and some applications of DLCs. The films have widespread applications as protective coatings in areas, such as magnetic storage disks, optical windows and micro-electromechanical devices (MEMs).

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Diamond-like amorphous carbon

The recent development in the field of superhard materials with Vickers hardness of ⩾40 GPa is reviewed. Two basic approaches are outlined including the intrinsic superhard materials, such as diamond, cubic boron nitride, C3N4, carbonitrides, etc. and extrinsic, nanostructured materials for which superhardness is achieved by an appropriate design of their microstructure. The theoretically predicted high hardness of C3N4 has not been experimentally documented so far. Ceramics made of cubic boron nitride prepared at high pressure and temperature find many applications whereas thin films prepared by activated deposition from the gas phase are still in the stage of fundamental development. The greatest progress has been achieved in the field of nanostructured materials including superlattices and nanocomposites where superhardness of ⩾50 GPa was reported for several systems. More recently, nc-TiN/SiNx nanocomposites with hardness of 105 GPa were prepared, reaching the hardness of diamond. The principles of de...

https://mediatum.ub.tum.de/doc/958917/file.pdf

The search for novel, superhard materials

A review of the preparation of carbon nitride films

Novel group 14 nitrides

Recent progress is presented regarding the development of plasma induced CVD technique for coatings of non-planar and thick tools and of the understanding or the origin of the high thermal stability of the nanocrystalline TiN/amorphous Si 3 N 4 superhard coatings up to 1100°C. A chlorine free, combined plasma CVD and PVD technique was developed for the deposition of superhard nc-TiN/c-BN nanocomposites. These coatings are compatible with the majority of engineering materials, such as ferrous and aluminum alloys and others. Their hardness reaches 70 GPa and elastic modulus E/(1-ν 2 )≈585 GPa. An industrial production reactor was built which enables one to deposit such coatings on cutting tools.

Recent progress in the superhard nanocrystalline composites : towards their industrialization and understanding of the origin of the superhardness

Compact thin films of stoichiometric, amorphous C3N4 have been prepared by means of chemical transport of carbon in intense nitrogen glow discharge at relatively high deposition temperature of about 800 °C. Their hardness reached 2500 Vickers (kg/mm2).

J. Weidmann

Papers

Plasma chemical vapor deposition and properties of hard C3N4 thin films