DLC is usually applied as coatings to other materials that could benefit from some of those properties.

The more common one has its carbon atoms arranged in a cubic lattice, while the less common one, lonsdaleite, has a hexagonal lattice.

By mixing these polytypes in various ways at the nanoscale level of structure, DLC coatings can be made that at the same time are amorphous, flexible, and yet purely sp 3 bonded diamond.

The hardest, strongest, and slickest is such a mixture, known as tetrahedral amorphous carbon (ta-C).

In 2006, the market for outsourced DLC coatings was estimated as about 30,000,000 in the European Union.

In October 2011, Science Daily reported that researchers at Stanford University have created a super-hard amorphous diamond under conditions of ultrahigh pressure, which lacks the crystalline structure of diamond but has the light weight characteristic of carbon.

The internal energy of the cubic polytype is slightly lower than that of the hexagonal form and growth rates from molten material in both natural and bulk synthetic diamond production methods are slow enough that the lattice structure has time to grow in the lowest energy (cubic) form that is possible for sp 3 bonding of carbon atoms.

In contrast, DLC is typically produced by processes in which high energy precursive carbons (e.g.

In those cases cubic and hexagonal lattices can be randomly intermixed, layer by atomic layer, because there is no time available for one of the crystalline geometries to grow at the expense of the other before the atoms are frozen in place in the material.

Amorphous DLC coatings can result in materials that have no long-range crystalline order.

Without long range order there are no brittle fracture planes, so such coatings are flexible and conformal to the underlying shape being coated, while still being as hard as diamond.

Structural elements are not crystallites but are nodules of sp 3 -bonded carbon atoms.

The grains are so small that the surface appears mirror smooth to the eye.

So the application of pressure, impact, catalysis, or some combination of these at the atomic scale can force sp 2 bonded carbon atoms closer together into sp 3 bonds.

This must be done vigorously enough that the atoms cannot simply spring back apart into separations characteristic of sp 2 bonds.

Usually techniques either combine such a compression with a push of the new cluster of sp 3 bonded carbon deeper into the coating so that there is no room for expansion back to separations needed for sp 2 bonding; or the new cluster is buried by the arrival of new carbon destined for the next cycle of impacts.

It is reasonable to envisage the process as a hail of projectiles that produce localized, faster, nanoscale versions of the classic combinations of heat and pressure that produce natural and synthetic diamond.

Because they occur independently at many places across the surface of a growing film or coating, they tend to produce an analog of a cobblestone street with the cobbles being nodules or clusters of sp 3 bonded carbon.

Depending upon the particular recipe being used, there are cycles of deposition of carbon and impact or continuous proportions of new carbon arriving and projectiles conveying the impacts needed to force the formation of the sp 3 bonds.

As a result, ta-C may have the structure of a cobblestone street, or the nodules may melt together to make something more like a sponge or the cobbles may be so small as to be nearly invisible to imaging.

A classic medium morphology for a ta-C film is shown in the figure.

The primary desirable qualities are hardness, wear resistance, and slickness (DLC film friction coefficient against polished steel ranges from 0.05 to 0.20 8 ).

DLC properties highly depends on plasma treatment 9 10 deposition parameters, like effect of bias voltage, 11 DLC coating thickness, 12 13 interlayer thickness, 14 etc.

Moreover, the heat treatment also change the coating properties such as hardness, toughness and wear rate.

However, which properties are added to a surface and to what degree depends upon which of the 7 forms are applied, and further upon the amounts and types of diluents added to reduce the cost of production.

In 2006 the Association of German Engineers, VDI, the largest engineering association in Western Europe issued an authoritative report VDI2840 16 in order to clarify the existing multiplicity of confusing terms and trade names.

It provides a unique classification and nomenclature for diamond-like-carbon (DLC) and diamond films.

It succeeded in reporting all information necessary to identify and to compare different DLC films which are offered on the market.

Dlc Info For Mac