In this paper, 1 k (i.e., 1000 fiber per bundle) T-300™ (Toray Institute Inc., Tokyo, Japan) and 12 k (i.e.,12,000 fiber per bundle) T-700™ (Toray Institute Inc., Tokyo, Japan) carbon fiber reinforced silicon carbide (C/SiC) pins are fabricated using the chemical vapor infiltration (CVI) method. For the 1 k T-300™ carbon fiber, the 2D [0°/90°] plain-woven (PW) laminated structure is adopted; and for the 12 k T-700™ carbon fiber, the Multi-axial Warp-Knitted (MWK) structure (i.e., [0°/45°/90°/-45°]) is adopted. Mechanical properties (i.e., tensile, compression, and flexure) of two types of C/SiC are evaluated. Three types of double-shear tests (i.e., the shear loading perpendicular (Type 1), parallel (Type 2), and 45° off-axial (Type 3) loading to the lamination of the C/SiC pins) are conducted to evaluate the shear mechanical properties for the C/SiC pins. Relationships between the double shear mechanical properties, loading type, fiber type, microstructures, and damage mechanisms are established. For 1 k T-300™ PW C/SiC pin, the double shear strength is τs = 74.66 ± 11.33 and 105.49 ± 8.6 MPa for test Type 1 and 2, respectively; and for 12 k T-700™ PW C/SiC pin, the double shear strength is τs = 104.33 ± 11.33, 202.82 ± 24.8, 86.56 ± 2.57 MPa for test Type 1, 2, and 3, respectively. Compared with 1 k T-300™ PW C/SiC pin, the double shear strength of 12 k T-700™ PW C/SiC pin increased 39.74 and 99.26% for test Type 1 and 2. The increases of the shear strength in 12 k T-700™ MWK C/SiC pins is due to the higher strength for 12 k T-700™ carbon fiber and the higher densification for the MWK fiber preform.
