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Atomic-scale simulations of ideal strength and deformation mechanism in β-SiC under H/He irradiation
摘要： We ?rstly investigated the mechanical responses of β-SiC to the tensile and shear strains under H/He irradiation using density functional theory, with a speci?c focus on the atomistic mechanism of deformation and fracture. The results revealed that the e?ect of introducing H/He on ideal strengths of tension and shear is limited, due to the strong sp3 bonds of Si-C. However, somehow large disparity in failure was discovered after introducing H/He. Under the tension, all Si-C bonds along the tensile direction are synchronously broken, causing cubic-to-graphitic transformation in the perfect β-SiC, in contrast to the asynchronous breakage of Si-C bonds in the H/He-doping systems. Under the shear, H- and He-doping systems display individual cleavage-like modes of lattice instability, respectively, whereas structural transformation by re-bonding new Si-C bonds is responsible for the failure in the perfect β-SiC. The cleavage-like modes were discussed, combining a detailed analysis of electronic structure. The mechanical response to H/He irradiation distinguishes β-SiC from conventional metals presently applied in nuclear industry. The study may provide a clue for new design strategy of irradiation-tolerant materials for energy applications.
关键词： Ideal strength,H/He irradiation,Deformation mechanism,β-SiC ceramic
更新于2025-09-23 15:23:52
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Structure and Phase Evolution in a SiC Ceramic Surface Layer During Electron-Beam Treatment
摘要： The elemental and phase compositions and substructure changes in the surface layer of SiC ceramic irradiated by pulsed electron beams of variable intensity were investigated. The structure and phase state of the ceramic surface layer were shown to be controlled by the electron-beam parameters. The electron-beam irradiation regimes leading to nanostructure detection in the SiC-ceramic surface layer were determined.
关键词： surface layer,electron beam,polytypes,SiC ceramic
更新于2025-09-19 17:15:36
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Porous SiC-mullite ceramics with high flexural strength and gas permeability prepared from photovoltaic silicon waste
摘要： In this paper, porous SiC-mullite ceramics (PSMCs) with high ?exural strength and gas permeability were prepared with various mass fractions of MoO3 and Al2O3. Higher performance was achieved at low sintering temperatures and the problem of large amounts of cristobalite phase in the PSMCs was solved. The results show that 4 wt% MoO3 is optimal for the growth of mullite rods at a sintering temperature of 850 °C. Porosity was e?ectively controlled by the formation of interlocking structure and mechanical strength was not obviously a?ected. Therefore, the optimal content of Al2O3 was 25 wt% in samples prepared at 850–1200 °C, as the ?exural strength was generally higher than that in samples with other Al2O3 contents. The highest ?exural strength of 66.02 MPa was achieved at an open porosity of 45.4%, gas permeability of 2.32 × 10?13 m2, and permeance of 4.62 × 10?5 mol m?2 s?1 Pa?1 in samples sintered at 1000 °C. This work is of signi?cance for the industrial preparation of PSMCs from photovoltaic silicon waste.
关键词： MoO3,Photovoltaic solid waste,Porous SiC ceramic,Mullite
更新于2025-09-11 14:15:04
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Effect of Ti addition on the wetting and brazing of Sn0.3Ag0.7Cu filler on SiC ceramic
摘要： The wetting behavior of Sn0.3Ag0.7Cu (SAC) filler with the addition of Ti on SiC ceramic was investigated using sessile drop method. SiC/SiC was brazed by SAC-Ti filler with different Ti content at 1223 K (950 °C) for 10 minutes. The wettability of SAC-Ti filler on SiC was significantly enhanced with the addition of Ti. The contact angle decreased at first and then increased with increasing Ti content. The lowest contact angle of 9° was obtained with SAC-1.5Ti (wt.%) filler. When Ti content further increased to 2.0 wt.%, the contact angle increased, due to the intense reaction of Ti-Sn. The reaction between Ti and SiC controlled the wetting behavior of SAC-Ti on the SiC substrate and the reaction products such as TiC and Ti5Si3 were formed. The wetting of SAC-Ti on SiC was reaction-controlled. Interfacial reaction products TiC and Ti5Si3 were observed. The wetting activation energy in spreading stage was calculated to be 129.3 kJ/mol. Completely filled SiC/SiC joints were obtained using the filler with Ti content higher than 0.5 wt.%. The fillet height increased firstly then decreased with mounting Ti content. The shear strength of joints increased first with the addition of Ti then decreased with Ti content increasing to 2.0 wt.%. The highest shear strength of 35.7 MPa was obtained with SAC-1.5 Ti (wt.%) filler.
关键词： wetting,brazing,Ti addition,Sn0.3Ag0.7Cu,SiC ceramic
更新于2025-09-04 15:30:14