Microstructural evolution and self‐healing mechanism of a 2D C/SiC‐BC_x composite under constant load in static wet oxygen and dynamic combustion atmosphere

Abstract

A 2D C/SiC-BC x composite was tested under static load in both wet oxygen and dynamic combustion atmospheres. The microstructural evolution and selfhealing mechanisms of the composites were investigated by a scanning electron microscope. The results indicated that the multi-scale deflection of cracks played an important role in improving the performance of 2D C/SiC-BC x in both atmospheres. The glass phase could seal the matrix cracks and flow into the fiber bundles through the cracks. As a result, the fibers and fiber/matrix interface within 2D C/SiC-BC x were protected from oxidation. The retention rate of hightemperature tensile strength of 2D C/SiC-BC x got a significant improvement in wet oxygen atmosphere at 700 8C, compared with 2D C/SiC. The damage rate of 2D C/SiC-BC x remained in a smaller scope in dynamic combustion atmosphere. The damage rates of the 2D C/SiC-BC x were about 80% and 90% lower than that of 2D C/SiC, respectively at 700 and 900 8C.

Long-term ceramic matrix composite for aeroengine

“…13(b) and 13(d), the matrix cracks were healed by glass phase derived from the oxidation of multilayered matrix. As a comparison, the unmodified C/SiC fractured when it was tested in the combustion environment for 6.7 h. The creep tests in a wet oxygen atmosphere at 700 ℃ were also conducted [106]. The damage rate of C/SiC-BC x composites was only about 0.95 MPa/h.…”

Stressed oxidation behaviors of 2D C/SiC-BCx composite under wet oxygen atmosphere

“…Then, the asreceived composites were machined and polished according to the shape and sizes of sample as shown in Fig. 1 [14]. Finally, the machined specimens were coated with two layers of BC x ceramic and two layers of SiC ceramic alternately by chemical vapor deposition (CVD).…”

“…2 [14], which can simulate the environments of aero-engine without consideration of gas velocity. Fig.…”

“…It is known to us that the creep stress is another important factor for the stressed oxidation. The effect of temperature on the stressed oxidation was presented in previous paper [14]. However, the effect of creep stress on stressed oxidation of 2D C/SiC-BC x composites has not been reported so far.…”

Utilization of Lyotropic Liquid Crystalline Gels for Chronic Wound Management

“…At the same time, the dry healing environment makes the wound easy to dehydrate and scab, which is not conducive to the crawling of epithelial cells. The growth factors secreted by the body will lose their biological activity easily, resulting in slow healing [ 14 ]. In addition, the dry environment cannot prevent bacterial invasion or maintain the humidity and temperature of the wound, which is not favorable for wound healing.…”