Diamond-Like Carbon Coating Centre (DLC3)

DLC³ in the School of Engineering and Design of Brunel Universityprovide an industrial service for coating components with diamond-like carbon and manufacture custom built diamond-like carbon coating.

DLC³ is led by Professor Joe Franks.

Diamond-like carbon is

• Hard but flexible therefore wear resistant
• Chemically inert therefore corrosion resistant
• Atomically dense therefore diffusion resistant
• Biocompatible

Diamond-like carbon provides

• A low friction surface
• A low adhesion surface
• A coating on a wide range of metals, ceramics, glasses and plastics

Carbon is a very versatile element, it owes its versatility to the different ways carbon atoms can bond to each other and to other elements. In graphite, carbon atoms bond strongly to each other within a plane but weakly between adjacent planes. Graphite is soft, electrically conducting and opaque. In diamond the bonding is strong in all directions. Diamond is the hardest known material, electrically insulating and transparent from the far ultra-violet to the far infra-red. Diamond films with excellent protective properties can be produced by vacuum deposition but the optimum substrate temperature for coating is about 900oC which severely limits the range of substrates to which diamond can be applied.

Near room temperature, an amorphous carbon containing coating can be produced in which a proportion of the carbon atoms are bonded as in diamond and which resemble diamond in many ways - hence diamond-like carbon (DLC).

Properties of DLC

The coating with its unique combination of properties is finding a rapidly growing range of applications in mechanical engineering and bio-engineering.

DLC coatings are:

• Wear resistant - hard but flexible
• Corrosion resistant - inert to acids, alkalis, solvents
• Lubricious - friction coefficient < 0.1
• Adherent - chemically bonded to the substrate
• Biocompatible - cell integrity maintained
• Haemocompatible - reduced blood coagulation
• Atomically dense - effective diffusion barrier

The Coating Process

Diamond-like carbon is produced when carbon is deposited under energetic conditions. Carbon is then strongly bonded in all directions as in diamond, but as an amorphous structure, while graphite is strongly bonded in a plane, but weakly between planes.

A method of producing the strongly bonded structure is by plasma assisted chemical vapour deposition (PACVD). Components to be coated are placed on an electrode, which is capacitively coupled to a radio frequency source. A carbon containing gas such as acetylene is ionised by the field and the positive carbon ions bombard the components forming the strongly bonded coating. In contrast to diamond, no external heating is applied, therefore temperature sensitive materials such as plastics and collagen can be coated as well as a wide range of metals and ceramics.

Biomedical

• Orthopaedic Implants
• Guide Wires
• Catheters
• Stents
• Bypass Conduits
• Drug Delivery
• Surgical Instruments
• Dental Filling Points

Automotive & Machinery

• Valve Trains
• CamShafts
• Rotating & Sliding Components

Machining

• Drills
• Machining Inserts
• Cutters
• Saws

Optical

• Germanium Optics

Other

• Magnetic Recording Heads
• Strain Guage Plates
• Packaging
• Moulds
• Impervious Masks
• Electron Emission
• Decorative

Director

Professor Joe Franks

Research Leaders

Professor Anthony Anson

Dr Robert Bulpett

Director

Professor Joe Franks

Postal Address

Professor Joe Franks
Diamond-Like Carbon Coating Centre
Brunel University,
Uxbridge, Middlesex,
UB8 3PH, United Kingdom
Tel: +44 (0) 1895 265863
Fax: +44 (0) 1895 812556

Location in University

Diamond-Like Carbon Coating Centre (DLC³)
Halsbury building