One dimensional Amosic-3 silicon carbide fiber reinforced silicon carbide matrix composites(SiCf/SiC minicomposites) prepared by chemical vapor infiltration were irradiated with 2.8 Me V proton ions. The ion fluences ...One dimensional Amosic-3 silicon carbide fiber reinforced silicon carbide matrix composites(SiCf/SiC minicomposites) prepared by chemical vapor infiltration were irradiated with 2.8 Me V proton ions. The ion fluences were 1.0 × 10^17 and 1.5 × 10^17cm^-2 at room temperature and 300℃, respectively. The microstructure and mechanical properties were investigated before and after proton irradiation. Raman spectra showed no evident change in Amosic-3 fibers regardless of irradiation temperature, which is confirmed by high resolution transmission electron microscopy observation. Pyrolytic carbon interphase showed slightly expansion after 300℃ irradiation, however, no microstructure changes were observed in SiC matrix. Moreover, it can be deduced that no irradiation induced changes in mechanical properties were observed after present proton irradiation.展开更多
C/C minicomposites were manufactured by CVI with propylene as resource gas and Ar as diluent gas. Effects of deposition temperature, the flow rate of propylene and total system pressure on the microstructure...C/C minicomposites were manufactured by CVI with propylene as resource gas and Ar as diluent gas. Effects of deposition temperature, the flow rate of propylene and total system pressure on the microstructure of C/C minicomposites were investigated. Deposition conditions are as follows: deposition temperature ranging from 870℃ to 1000℃, the flow rate of propylene from 10 to 60 ml/min, and total system pressure from 3 to 16kPa. The results revealed: The deposit distributes non uniformly as increasing the deposition temperature or total system pressure. The effect of the flow rate of propylene on the distribution of deposit observes different principles at different deposition temperatures. If the deposition temperature rises to 900℃, the deposit distributes more non uniformly as increasing the flow rate of propylene. The morphology of deposit varies with deposition condition, such as smooth, droplet like or spike like. Deposition mechanism varies with deposition condition. It can be surface reaction nucleation and growth, heterogeneous nucleation of liquid droplet on carbon fiber or gas borne nuclei growth. With the principle of nuclei growth of crystal and the method of phenomenology, the changes of deposition mechanism and the morphology of pyrolytic carbon with deposition condition were explained successfully. The effect of deposition condition on deposit homogeneity stems from the effect of deposition condition on the CVI kinetics and the deposition mechanism of pyrolytic carbon.展开更多
基金supported by the National Natural Science Foundation of China (No.11575143)the Creative Research Foundation of Science and Technology on the Thermostructural Composite Material Laboratory (No.6142911030411)+1 种基金the Fundamental Research Funds for the Central Universities (No. 3102019TS0403)Science and Technology on Combustion, Internal Flow and Thermo-Structure Laboratory (No.6142701190302)
文摘One dimensional Amosic-3 silicon carbide fiber reinforced silicon carbide matrix composites(SiCf/SiC minicomposites) prepared by chemical vapor infiltration were irradiated with 2.8 Me V proton ions. The ion fluences were 1.0 × 10^17 and 1.5 × 10^17cm^-2 at room temperature and 300℃, respectively. The microstructure and mechanical properties were investigated before and after proton irradiation. Raman spectra showed no evident change in Amosic-3 fibers regardless of irradiation temperature, which is confirmed by high resolution transmission electron microscopy observation. Pyrolytic carbon interphase showed slightly expansion after 300℃ irradiation, however, no microstructure changes were observed in SiC matrix. Moreover, it can be deduced that no irradiation induced changes in mechanical properties were observed after present proton irradiation.
文摘C/C minicomposites were manufactured by CVI with propylene as resource gas and Ar as diluent gas. Effects of deposition temperature, the flow rate of propylene and total system pressure on the microstructure of C/C minicomposites were investigated. Deposition conditions are as follows: deposition temperature ranging from 870℃ to 1000℃, the flow rate of propylene from 10 to 60 ml/min, and total system pressure from 3 to 16kPa. The results revealed: The deposit distributes non uniformly as increasing the deposition temperature or total system pressure. The effect of the flow rate of propylene on the distribution of deposit observes different principles at different deposition temperatures. If the deposition temperature rises to 900℃, the deposit distributes more non uniformly as increasing the flow rate of propylene. The morphology of deposit varies with deposition condition, such as smooth, droplet like or spike like. Deposition mechanism varies with deposition condition. It can be surface reaction nucleation and growth, heterogeneous nucleation of liquid droplet on carbon fiber or gas borne nuclei growth. With the principle of nuclei growth of crystal and the method of phenomenology, the changes of deposition mechanism and the morphology of pyrolytic carbon with deposition condition were explained successfully. The effect of deposition condition on deposit homogeneity stems from the effect of deposition condition on the CVI kinetics and the deposition mechanism of pyrolytic carbon.
