SiC matrix/SiC fiber composite: A high-heat flux, low activation, structural material

Knudsen diffusivities and properties of structures of unidirectional fibers

“…For a structure undergoing densification, by chemical vapor infiltration for example, the rings added around the fibers of the original nonoverlapping fiber structure, displayed using solid black pattern, correspond to the material deposited within the preform during the process. It is interesting to point out that the structure of Figure 2 is qualitatively similar to micrographs of partially densified structures reported in the literature (e.g., Hopkins and Chin, 1986). While nonoverlapping or freely overlapping fiber structures can uniquely be identified by their porosity and fiber radius, structures of partially overlapping fibers need for their unique identification the porosity of the nonoverlapping fiber structure from which they were obtained or, equivalently, the radius of the hard core of the fibers as well.…”

“…Among the simplest structures of initially nonoverlapping fibers that one can consider is that of unidirectional (parallel) nonoverlapping fibers, positioned in space through some randomizing process. Such a structure is representative, in almost every important detail, of preforms of unidirectional fibers used for reinforcement of ceramic materials (Meyers and Chawla, 1984;Hopkins and Chin, 1986). Densification of these porous media through a solid deposition process gives rise to a partially overlapping fiber structure that can be viewed as consisting of randomly positioned parallel cylinders having a cylindrical hard core of radius equal to that of the fibers of the initial structure.…”

Mechanical‐ and Physical‐Property Changes of Neutron‐Irradiated Chemical‐Vapor‐Deposited Silicon Carbide

“…T HE consideration of silicon carbide (SiC) as a candidate structural material for fusion applications has been discussed extensively in the literature for the past two decades. [1][2][3][4][5][6][7][8][9] Attractive characteristics of SiC include its low density and good mechanical properties at elevated temperatures, as well as its low neutron activation. However, similar to many other ceramic systems, the widespread use of SiC in engineering applications has been limited by its low fracture toughness, which is typically 2.5-4.0 MPaиm 1/2 , based on conventional fracture toughness techniques.…”

Preparation of Carbon Fiber/SiC Composite by Chemical Vapor Infiltration.

“…Maximum strength of 800 MPa was observed at the surface layer thickness of 50 pm. (5) Fracture toughness estimated depends on the porosity and was 6-10 MPa ' ml/2 at a porosity of 20 olo. (6) It is expected that mechanical properties of CVI carbon fiberslSiC composite can be improved by decreasing porosity and thickness of SiC Iayer coated on the composite.…”