Tailoring Mechanical Properties of a-C:H:Cr Coatings
Abstract
The development of coatings with tunable performances is critical to meet a wide range
of technological applications each one with different requirements. Using the plasma-enhanced
chemical vapor deposition (PECVD) process, scientists can create hydrogenated amorphous carbon
coatings doped with metal (a-C:H:Me) with a broad range of mechanical properties, varying from
those resembling polymers to ones resembling diamond. These diverse properties, without clear
relations between the different families, make the material selection and optimization difficult but
also very rich. An innovative approach is proposed here based on projected performance indices
related to fracture energy, strength, and stiffness in order to classify and optimize a-C:H:Me coatings.
Four different a-C:H:Cr coatings deposited by PECVD with Ar/C2H2 discharge under different bias voltage and pressures are investigated. A path is found to produce coatings with a selective critical energy release rate between 5–125 J/m2 without compromising yield strength (1.6–2.7 GPa) and elastic limit (≈0.05). Finally, fine-tuned coatings are categorized to meet desired applications under different testing conditions.
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