Ablation under oxyacetylene torch with heat flux of 4186.8 (10% kW/m2 for 20 s was performed to evaluate the ablation resistance of C/C–SiC composites fabricated by chemical vapor infiltration (CVI) combined with liquid silicon infiltration (LSI) process. The results indicated that C/C–SiC composites present a better ablation resistance than C/C composites without doped SiC. The doped SiC and the ablation products SiO2 derived from it play key roles in ablation process. Bulk quantities of SiO2 nanowires with diameter of 80 nm–150 nm and length of tens microns were observed on the surface of specimens after ablation. The growth mechanism of the SiO2 nanowires was interpreted with a developed vapor–liquid–solid (VLS) driven by the temperature gradient.
For the numerical simulation of hot working process of spray-formed FGH4095, the high temperature deformation behavior of spray-formed FGH4095 is studied at different deformation temperatures (1010-1140 ℃) and different strain rates (0.001-10.0 s-1) using Gleeble 3800 thermal simulator. The constitutive equation is established with the sinh model. The calculative results are consistent with the experimental data. It indicates that the accurate material model is provided for the numerical simulation for hot working process of spray-formed FGH4095.
Effects of helium implantation on silicon carbide (SiC) and graphite were studied to reveal the possibility of SiC replacing graphite as plasma facing materials. Pressureless sintered SiC and graphite SMF-800 were implanted with He+ ions of 20 keV and 100 keV at different temperatures and different fluences. The He+ irradiation induced microstructure changes were studied by field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM).
B4C. S i c and C. Cu functionally graded-materials (FGMs) have been developed by plasma spraying and hot pressing. Their high-heat flux properties have been investigated by high energy laser and electron beam for the simulation of plasma disruption process of the future fusion reactors, And a study on eroded products of BqC/Cu FGhl under transient thermal load of electron beam was performed. In the experiment: SEM and EDS analysis indicated that B4C and S i c were decomposed, carbon was preferentially evaporated under high thermal load, and a part of Si and Cu were melted, in addition, the splash of melted metal and the particle emission of brittle destruction were also found. Different erosive behaviors of carbon-based materials (CBRIs) caused by laser and electron beam were also discussed.
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