Macroporosity and interface cracking in multi-directional carbon-carbons

摘要: Abstract The microstructure of multi-directional carbon-carbons is described from a mini-mechanical viewpoint. Shrinkage cracks, thermal-stress cracks and bubblelike pores appear to be unavoidable results heat treatment, constitute the main types macroporosity in 3-D carbon-carbons. While shrinkage bubble weaken matrix phase, are probably more important influence on thermo-mechanical behavior service because they occur at interfaces, open close with heating cooling. A simple mathematical model describes formation cracks; analysis confirmed qualitatively by microscope observations heated composites. Examples composite discussed briefly show that degraded tensile strength, low thermal expansions nonlinearity, bimodularity hysteresis stress-strain responses may attributed noted microstructural imperfections; some effects especially near free surfaces, where interconstituent slippage can shear-lag situations. Friction plays large role and, therefore, deserves further study.