JP Journal of Solids and Structures
Volume 3, Issue 3, Pages 177 - 212
(November 2009)
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EXTENSION OF FUNDAMENTALS ON sp3 GROWTH MECHANISMS, AND STRESS OPTIMIZATION IN HARD CARBON COATING ENGINEERING
Stéphane Neuville (France)
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Abstract:
Up to now, only a limited number of depositing means have been used to produce ta-C coatings whereas many others are expected to be developed with the proper association and optimization of all identified effects in favour of sp3 sites. Yet, most actually used corresponding depositing devices suffer, in general, from a number of limiting drawbacks, concerning depositing rates, substrate shape and size, adhesion and stress which have to be reduced for many expected applications of the ta-C and related material coatings.
In order to look about the possibility to optimize the depositing of better performing ta-C coatings of lower intrinsic stress, we proceed with some qualitative theoretical investigation on the coating growth mechanisms over the depth and the substrate surface of all types of atomic rearrangement effects. Some of those will produce stress by subplantation effects and some others are known to relax them. However, it has to be distinguished between those who will degrade the coating to more graphitic materials, and others which can be in favour of some sp3 enhancement. This qualitative analysis suggests the combination of appropriate coating devices which make possible the optimization of the process parameters with which the sp3 atomic rearrangements will be enhanced, and at same time the intrinsic stress will be reduced. Therefore, in association to the optimization of the coating/substrate interface, these newly developed considerations are suggested to be used for the optimisation of coater design features and search of best possible compromises to be achieved between stress, and combination of actual outstanding properties of ta-C and related coatings. |
| Keywords and phrases: ta-C, sp3 growth mechanisms, upscaling, reduction of stress. |
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