Influence of Interface Characteristics on the Mechanical Properties of Hi‐Nicalon type‐S or Tyranno‐SA3 Fiber‐Reinforced SiC/SiC Minicomposites

Abstract

The tensile behavior of CVI SiC/SiC composites with Hi‐Nicalon type‐S (Hi‐NicalonS) or Tyranno‐SA3 (SA3) fibers was investigated using minicomposite test specimens. Minicomposites contain a single tow. The mechanical behavior was correlated with microstructural features including tow failure strength and interface characteristics. The Hi‐NicalonS fiber‐reinforced minicomposites exhibited a conventional damage‐tolerant response, comparable to that observed on composites reinforced by untreated Nicalon or Hi‐Nicalon fibers and possessing weak fiber/matrix interfaces. The SA3 fiber‐reinforced minicomposites exhibited larger interfacial shear stresses and erratic behavior depending on the fiber PyC coating thickness. Differences in the mechanical behavior were related to differences in the fiber surface roughness.

Prediction of the Mechanical Behavior of a Minicomposite Based on Grey Verhulst Models

“…Thus the initial condition can be finally determined after comparison of the fitting degrees. As shown in Figure 5, an excellent agreement was also achieved by the predicted curve with the initial condition set as ε = ε(5), E = E (5) (1) Since the energy of AE has shown to be a good measure of matrix cracking for CMCs, the stress-strain constitutive behavior seems to be very clearly a reflection of the AE energy curve. It was also confirmed by the three corresponding domains shown in both the curves.…”

“…Up to now this approach has been used to study the mechanical/fatigue properties of CMCs with different commercial fibers including Nicalon and Hi-Nicalon at room/elevated temperatures [5][6][7][8][9]. However, most previous studies were mainly focused on SiC-fiber-reinforced composite systems, whereas the mechanical behavior and the corresponding modeling of C/SiC minicomposites has been little reported.…”

Evaluation of damage accumulation behavior and strength anisotropy of NITE SiC/SiC composites by acoustic emission, digital image correlation and electrical resistivity monitoring

“…Such significant difference may also be explained by co-working strong clamping at the F/M interface. Due to the high modulus of the fiber and the rough high-crystalline SiC fibers [8], sliding was hardly expected owing to strong clamping at the F/M interface even when cracking. Higher frictional stress for rough surfaced Tyranno-SA3 fiber composites may support this hypothesis [9].…”

Oxidation behavior of SiBC matrix modified C/SiC composites with different PyC interphase thicknesses

“…As PyC interphase thickness increased, room-temperature flexural strength of C/SiC-SiBC composites increased. This might result from the gradually weakened interfacial bonding strength which guaranteed sufficient crack deflection and load transfer to the fiber [15,19,20]. The retained flexural strength ratios were 77%, 80% and 87% for specimen C-50, C-180 and C-300 respectively, after oxidization at 800 1C.…”