crack through the material. The force required for crack propagation varies between different types of CMCs. In the table, CVI, LPI, and LSI denote the manufacturing process of the C/SiC-material. Data on the oxide CMC and SiSiC are taken from manufacturer datasheets. The tensile strength of SiSiC and were calculated from measurements of elongation to fracture and Young's modulus, since generally only bending strength data are available for those ceramics. Averaged values are given in the table, and significant differences, even within one manufacturing route, are possible. Tensile tests of CMCs usually show nonlinear stress-strain curves, which look as if the material deforms plastically. It is called quasi-plastic, because the effect is caused by the microcracks, which are formed and bridged with increasing load. Since the Young's modulus of the load-carrying fibers is generally lower than that of the matrix, the slope of the curve decreases with increasing load. Curves from bending tests look similar to those of the crack resistance measurements shown above. The following features are essential in evaluating bending and tensile data of CMCs: CMC materials with a low matrix content (down to zero) have a high tensile strength (close to the tensile strength of the fiber), but low bending strength. CMC materials with a low fiber content (down to zero) have a high bending strength (close to the strength of the monolithic ceramic), but no elongation beyond 0.05% under tensile load. The primary quality criterion for CMCs is crack resistance behavior or fracture toughness. High Temperature Creep Properties Although CMCs are able to operate at very high temperatures, creep deformation still occur around 1000 °C, in the range of certain high-temperature applications. Creep acts on either the matrix or fiber depending on the creep mismatch ratio (CMR) between the effective fiber strain rate and effective matrix strain rate. The component with the smaller strain rate bears the load and is susceptible to creep. The three main creep stages are governed by the creep mismatch ratio. During primary creep, internal stresses are transferred allowing the CMR to approach unity, as well as the secondary creep stage. The tertiary creep stage, where failure occurs, can be governed by fiber creep, where failure occurs due to fiber fracture, or matrix creep, which lead to matrix cracking. Usually, matrix creep strength is worse than the fiber, so the fiber bears the load. However, matrix cracking can still occur with weak