High temperature properties of SiC and diamond CVD-monofilaments

Abstract

The chemical, structural and thermomechanical properties of SiC and diamond CVD-monofilaments have been investigated. Electron and Raman microprobe analyses showed graded radial atomic and phase distributions in the SiC filaments. Thermomechanical investigations (tensile/bending elastic modulus/creep tests) were carried out on single filaments and these properties were correlated with the physicochemical features. The thermal behaviour of the CVD-SiC filaments is strongly related to the nature and the amounts of intergranular secondary phases (free carbon or silicon). The strong covalent bonds and the microcrystalline state of the CVD-diamond filaments give rise to an outstanding thermal behaviour.

Interfacial shear strength behaviour of Ti/SiC metal matrix composites at room and elevated temperature

“…The SM2156 fibre consists of SiC deposited on a 15-lm tungsten core, with a 5-lm pyrocarbon coating and an overall filament diameter of $140 lm [30]. It was produced by QinetiQ (now TISICS Ltd.).…”

Microstructure of SiC fiber fabricated by two-stage chemical vapor deposition on tungsten filament

“…Methods for preparing SiC fibers usually involve chemical vapor deposition (CVD) of SiC on some kinds of substrate. It is known that tungsten has been successfully used as a substrate to manufacture Sigma series SiC fiber [4], as well as carbon substrate being utilized in SCS series SiC fiber [5]. On the other hand, from the viewpoint of crystal nucleation and growth, Radmilovic et al [6] and Liu et al [7] investigated the origin and growth habit of CVD SiC grains, the relationship between texture and twins, stacking faults in a thin SiC film deposited on substrate of silicon and graphite, respectively.…”

Evaluating high temperature elastic modulus of ceramic coatings by relative method

“…10, i.e., the elastic modulus measured by this work increased at first and then decreased, whereas the modulus tested by Refs. [51][52][53] just decreased with the rise of temperature. This difference is most probably caused by the different sample conditions, i.e., the HT modulus are measured in situ in this work, but the free-standing SiC samples were required to be used in Refs.…”

“…Also the comparison among the measured temperaturemodulus profile and the other measurements [51][52][53][54] is showed in Fig. 10.…”

“…This difference is most probably caused by the different sample conditions, i.e., the HT modulus are measured in situ in this work, but the free-standing SiC samples were required to be used in Refs. [51][52][53]. The in situ measurements of the HT modulus of the SiC coatings are influenced by the thermal stress generated by the mismatch of the thermal expansion coefficients between the coating and substrate materials during the course of heating.…”