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Research |
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Diamond-like Carbon (DLC)
Diamond-like carbon, in contrast to the sparkling, brilliant-cut gem stone, is a thin-film coating - dense, inert, low friction and hard wearing. The diverse range of areas exploiting diamond-like carbon (DLC), including electronics, razors, manufacturing and medical devices, utilise a spectrum of materials that the name covers. The umbrella term includes amorphous carbon, hydrogenated and tetrahedral variants; material that can be akin to polymers, graphite or diamond. However, in contrast to the well defined crystalline structures of more well known carbon-based materials, DLC has no long-range order, but contains both graphitic and diamond-like bonded carbon atoms, and usually for the applications discussed here, a significant level of hydrogen. Tuning the balance of these constituents allows the creation of a material with properties that can be finely tailored to match the application. ETCbrunel research includes applications such as novel medical devices, machine tool efficiency, and aircraft components. Our work investigates the nanostructure and nature of the material that leads to these beneficial properties. A publication list reflecting materials science and engineering application with links to publishers’ sites can be found at the bottom of the page. More details on research projects are given below: |
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SEM images showing degradation of drill bit surface of uncoated tool (top) and improved surface of DLC coated drill bit after four times tool use. |
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Energy Efficiency of Machining Tools |
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One application of thin film coatings is to improve the energy efficiency and cutting performance of machining tools. This is facilitated by deposition of diamond-like carbon (DLC) coatings on steel machine parts and tools, producing an optimized surface with low friction, low wear rate and high performance. SEM, EDX and AFM surface analyses elucidate the modes and mechanisms of efficiency increase, showing the usefulness of DLC coatings for engineering applications. This work is in association with coating company Renishaw Advanced Materials. Achievements include substantial tool life improvements, of up to five times longevity, coupled with 36% reduction in power consumption, as highlighted in our publication in Diamond and Related Materials: “Energy efficiency improvements in dry drilling with optimised diamond-like carbon coatings”
These findings have led to a new Technology Strategy Board funded collaborative project to develop tools for Smart and Effective Engineering Manufacturing. |
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Interdisciplinary research, involving materials scientists, physicists, mechanical engineers, biomedical specialists and clinicians, is continuously expanding the potential and applications of diamond-like carbon and enhanced carbon based materials in the medical sector.
Medical implants made of metal alloys may elicit immune system responses, due to bulk or trace elements. Commonly used alloys include metals such as nickel, chrome and cobalt, which are known to cause allergic response in sensitized individuals.
Diamond-like carbon (DLC), deposited onto prostheses to act as a diffusion barrier, has given encouraging results in experimental and commercial products, at several physiological sites. The popularity of diamond-like carbon for medical devices is not solely related to the diffusion barrier properties, the surface topological, tribological and chemical properties make the material useful in many medical areas. Cardiovascular applications utilise the haemocompatibility and anti-thrombogenic properties of DLC; the surface structure of the coating reduces the likelihood of blood clots when a material is inserted into the blood stream. Capitalising on this, diamond-like carbon coated arterial stents are commercially available, preventing closure of arteries and ensuring unobstructed blood flow.
Work developing coatings for novel surgical tools is detailed in the article:
“Diamond-like carbon coating of alternative metal alloys for medical and surgical applications”
Our short review article in Materials World investigates application across the medical sector
“In Diamond Health: Diamond-like carbon for medical devices”
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Electroplated chromium coatings are extensively used on aircraft landing gear components to improve their functionality and reduce wear. The plating process is used both for applying hard coatings during manufacture, and for general restoration of worn or corroded parts during overhaul. However, the basic technology and processes are hazardous to both the environment and operators’ health, causing exposure to carcinogenic chemicals such as hexavalent chromium.
A collaborative research project with ETCbrunel, Hawker Pacific and the School of Engineering at Brunel, have developed a novel coating based on DLC which has great potential in restoring aircraft components in a more efficient and environmentally friendly manner.
“Diamond-like carbon / epoxy combination low-friction coatings to replace electroplated chromium”
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Biomedical Coating |
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ETCbrunel’s diamond-like carbon publications include the following articles, click on a link for the publishers’ website (where available, via DOI) some articles are also available on the University’s open access system, BURA or email bj.jones@brunel.ac.uk:
“Argon plasma treatment techniques on steel and effects on diamond-like carbon structure and delamination”
“Diamond-like carbon coating of alternative metal alloys for medical and surgical applications”
“Diamond-like carbon / epoxy combination low-friction coatings to replace electroplated chromium”
“Nanostructure and paramagnetic centres in diamond-like carbon: effect of Ar in PECVD process”
“In Diamond Health: Diamond-like carbon for medical devices”
“Energy efficiency improvements in dry drilling with optimised diamond-like carbon coatings”
“An EPR study at X- and W-Band of defects in a-C:H films in the temperature range 5K- 300K” B.J. Jones, R.C. Barklie, G. Smith, H. El Mkami, J.D. Carey and S.R.P. Silva Diamond and Related Materials 12 (2003) 116
“Electronic properties of amorphous carbon nitride films investigated using vibrational and ESR characterisations”
“Electron delocalization in amorphous carbon by ion implantation” R.U.A. Khan, J.D. Carey, S.R.P. Silva, B.J. Jones and R.C. Barklie Physics Review B 63 (2001) 121201(R)
“Electron paramagnetic resonance study of ion implantation induced damage in amorphous carbon thin films”
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Materials for Aerospace |
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Group Lead: |