Bulk Si(O)C ceramics are fabricated from polycarbosilane (PCS) by bulk pyrolysis along the route of cross linking, warm‐pressing, and pyrolysis. The PCS was thermally oxidized for cross linking at various temperatures as a critical step toward the bulk transformation of PCS into bulk Si(O)C ceramics. The degree of cross linking of PSC affects the densities and bonding qualities of the warm‐pressed powder compacts and, hence, the resultant ceramics. Under optimized processing conditions, crack‐free bulk Si(O)C ceramics are obtained with a bulk density attaining 2.2 g/cm3. Despite the existence of a considerable amount of oxygen in the ceramics (16.08 wt%), resulting from the thermal oxidation processing, the ceramics show the characteristics of structures and properties of SiC‐based ceramics. 29Si‐solid state nuclear magnetic resonance spectra (NMR) reveal that the as‐pyrolyzed X‐ray amorphous Si(O)C phase consists mainly of SiC4 coordination units in the ceramic network, with the remainder being silicon‐coordinated carbon and oxygen. Microhardness tests show that the as‐pyrolyzed amorphous Si(O)C ceramics have a high hardness, attaining 24.91 GPa at a load of 2 N, and 19.82 GPa at a load of 10 N. Upon annealing at 1300°C in argon, the amorphous ceramics crystallized into nanophase β‐SiC ceramics, and the ceramics kept the bulk nature of the amorphous ceramics with an increased density. The 29Si‐solid state NMR spectrum indicates that the nanophase β‐SiC ceramics consist of SiC4 units together with some mixed coordination units, namely SiO2C2 and SiOC3. The hardness of the crystallized nanophase Si(O)C ceramics attains 23.20 GPa at a load of 10 N. The present study demonstrates the possibility of fabricating bulk Si(O)C ceramics via the polymer‐processing route, resulting in ceramics with promising structural and mechanical properties.

According to the characteristic of polyhydroxy alcohol fracturing fluid system, the regeneration of the system was investigated for the first time. A stable organic boron crosslinking poly (vinyl alcohol) regenerable polyhydroxy alcohol fracturing fluid system was prepared, and the rheological property of the polyhydroxy alcohol fracturing fluid system with different regenerable times was also researched. The effect of regenerable times on the rheological property of the system was studied. The results indicated that the aims of gel breaking and regeneration can be achieved by regulating its pH value and controlling its crosslinking degree. With the increment of the regenerable time, both the temperature resistance and shearing resistance performances were decreased, and the viscoelasticity of the gel was also reduced.