Thermal Expansion of Laminated, Woven, Continuous Ceramic Fiber/Chemical‐Vapor‐Infiltrated Silicon Carbide Matrix Composites

Thermal expansions of three two‐dimensional laminate, continuous fiber/chemical‐vapor‐infiltrated silicon carbide matrix composites reinforced with either FP‐Alumina (alumina), Nextel (mullite), or Nicalon (Si‐C‐O‐N) fibers are reported. Experimental thermal expansion coefficients parallel to a primary fiber orientation were comparable to values calculated by the conventional rule‐of‐mixtures formula, except for the alumina fiber composite. Hysteriesis effects were also observed during repeated thermal cycling of that composite. Those features were attributed to reoccurring fiber/matrix separation related to the micromechanical stresses generated during temperature changes and caused by the large thermal expansion mismatch between the alumina fibers and the silicon carbide matrix.