Data on SiC-based bundle lifetime variability: The insufficiency of external phenomena affecting the flaw size.

A broad variability characterizes the lifetime of SiC-based bundles under static fatigue conditions at intermediate temperature and ambient air, challenging the accuracy of its prediction. The same is true, in a lower extend, with tensile properties, in apparent discrepancy with the bundle theory based on weakest link theory. The data presented here focus on lifetime scattering, evaluated on different fiber types (6 in total, Nicalon® or Tyranno®). It is hosted at http://dx.doi.org/10.17632/96xg3wmppf.1 and related to the research article "Static fatigue of SiC-based multifilament tows at intermediate temperature: the time to failure variability" (Mazerat et al., 2020) [1]. The insufficiency of classically invoked external and discrete bias (fiber sticking phenomenon for instance) was compared to a devoted Monte Carlo algorithm, attributing to each filament a strength (random) and a stress (homogeneous). Introduction of a stress inconsistency from tow to tow, experimentally observed through section variability, was revealed to overpass such biasing approach. This article can be referred to for the interpretation or prediction of CMC lifetime to guaranty long term performances over the broad offered application field.

Dataset on fractographic analysis of various SiC-based fibers.

This data article reports a systematic fractographic analysis of SiC-based filaments aiming at stress intensity factors assessment. A total of 11 fiber types (as-received or chlorinated Nicalon® and Tyranno® of all three generations) where therefore repeatedly tensile tested to generate the fracture surfaces. The tensile strengths were found to be independent to defect location (surface or internal). The well-known linear square root dependence of strength on mirror, mist or hackle outer radius was reaffirmed. These measurements reveal some residual tensile stresses on Nicalon® fibers, statement however questioned by the broad data scattering. Moreover, it is shown the surface etching treatment didn't affected (generating or releasing) such residual stress. A null y-intercept was consequently adopted to assess the characteristic stress intensity factors (KIC , mirror, mist or hackle constants). The toughness (KIC ) estimated this way ranges from 1.0 to 1.9 MPa m1/2 and shows a clear dependency to substrate composition: higher values were extracted on oxygen-free fibers. The Am /KIC ratio, estimated to equal 1.8 and independent to substrate type, is a key parameter that would assist further fractographic investigations.

Statistical data for the tensile properties and static fatigue of sic-based bundles.

Due to their high specific strength at elevated temperatures and resistance to oxidative environments, SiC-based fibers are of great interest for the reinforcement of ceramic matrix composites. They are however subjected to a slow crack growth (SCG) phenomenon causing their delayed failure under subcritical conditions. The testing of filaments, other than comprising handling difficulties, requires large sets of data (broadly dispersed), drawback alleviated by multifilament tow testing. The data available in the present paper correspond to a comprehensive mechanical characterization and static fatigue testing of various types of SiC-based fiber bundles. The initial non-linearity of load displacement curves were analyzed to reveal the tow structure originating from filament misalignment. Static fatigue tests were used to assess the lifetime prediction coefficients and its distribution parameters. These data may found interest for the interpretation of dispersion bundle testing can highlight under different solicitation mode. Such data are also prominent for the wealth of composite design and to guaranty long term performances over the broad application field offered.

Macroscopic fibers and ribbons of oriented carbon nanotubes.

A simple method was used to assemble single-walled carbon nanotubes into indefinitely long ribbons and fibers. The processing consists of dispersing the nanotubes in surfactant solutions, recondensing the nanotubes in the flow of a polymer solution to form a nanotube mesh, and then collating this mesh to a nanotube fiber. Flow-induced alignment may lead to a preferential orientation of the nanotubes in the mesh that has the form of a ribbon. Unlike classical carbon fibers, the nanotube fibers can be strongly bent without breaking. Their obtained elastic modulus is 10 times higher than the modulus of high-quality bucky paper.