Microstructural evolution of the latest generation of small‐diameter SiC‐based fibres tested at high temperatures

摘要: The new generation of silicon-carbide-based fibres made from organosilicon precursors, cross-linked by electron irradiation, have been compared with the earlier which undergone cross-linking in air. latest fibres, known as Tyranno Lox-E and Hi-Nicalon, possess a lower oxygen content (≈5 wt% ≈0.5 wt%) whereas NLM202 contain 12 wt% Lox-M 13 oxygen. produced precursor similar to that used produce Nicalon but modified addition titanium. All structure composed β-SiC grains, free carbon aggregates, no crystallized titanium compounds an oxygen-rich intergranular phase, except Hi-Nicalon fibre. fibre has largest grain size its is higher than fibres. For all grains grow when temperature increases, whilst strengths Young's moduli decrease. shows least change tensile properties. stiffer stronger others at high temperature. TEM results show growth isotropic, even during creep tests. depends on nature amount phase. Mechanical changes function can be explained external oxidation tests air internal facilitated nanoporosity, greater presence phase three containing most decreases resistance. Titanium does not improve mechanical properties resistance beyond 1523 K any positive influence limiting SiC growth. are less well stabilized shown consistently better temperatures, including resistance, other studied. sensitive