Characterisation of CVD carbon coatings on Nextel™440 fibres

Abstract

Carbon coatings were deposited on Nextel TM 440 fibres using C 3 H 6 -Ar system by hot wall chemical vapour deposition (CVD) with a total pressure of 1?5 kPa. The morphology and structure of the coatings were characterised by SEM, XRD and Raman spectroscopy. As the deposition temperature increased from 1173 to 1373 K, the growth rate increased complying with the Arrhenius law, and the calculated apparent activation energy was 45?9 kJ mol 21 . The coating growth was controlled by surface reaction, and smooth coatings were obtained. Above 1373 K, the free energy barrier for the formation of critical nucleus in gas phase was so low that remarkable nucleation occurred, thereby leading to the growth of rough coatings. The grain size and orientation of the coatings both increased as the deposition temperature increased. Additionally, the strength of the fibres coated at 1173 K was the highest, owing to low fibre degradation and healing effect of the thin coatings.

Effect of Y2O3 addition on the phase composition and crystal growth behavior of YSZ nanocrystals prepared via coprecipitation process

“…The activation energy for crystal growth (∆E) is estimated by the Arrhenius equation (Eq. (7)) [30]:…”

Effect of PyC coating on mechanical properties of Cf/AZ91D composites

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Effect of CVD carbon coatings on properties of SiC fibres

“…13 CVD is a common technique for depositing carbon coatings by decomposing hydrocarbons on a hot substrate. 14,15 CVD carbon coatings are usually prepared at low pressure, 16 which brings high costs associated with vacuum equipment and goes against mass production. The utilisation of a system operating at atmospheric pressure is important to reduce cost of ownership and achieve mass production.…”