Dislocation Analysis of 3C-SiC Nanoindentation with Different Crystal Plane Groups Based on Molecular Dynamics Simulation

To explore the deformation law of nanoindentation dislocations of different crystal plane groups of 3C-SiC by cube indenter. The molecular dynamics simulation method is used to construct the different crystal plane family models of 3C-SiC, select the ensemble, set the potential function, optimize the crystal structure, and relax the indentation process. The radial distribution function, shear strain, and dislocation deformation of nanoindentation on (001), (110), and (111) planes were analyzed, respectively. In the radial distribution function, the change in g r in the (110) crystal plane is the most obvious. Shear strain and dislocation occur easily at the boundary of square indentation defects. During the indentation process, the shear strain is enhanced along the atomic bond arrangement structure, (001) crystal plane shear strain is mainly concentrated around and below the indentation defects and produce a large number of cross dislocations, (110) the crystal plane shear strain is mainly concentrated in the shear strain chain extending around and below the indentation defect, which mainly produces horizontal dislocations, and (111) the crystal plane shear strain is mainly concentrated in four weeks extending on the left and right sides in the direction below the indentation defect and produces horizontal and vertical dislocations. The direction of shear stress release is related to the crystal structure. The crystal structure affects the direction of atomic slip, resulting in the results of sliding in different directions. The final dislocation rings are different, resulting in different indentation results.

A Microbial Induced Synthesis of Hydroxyapatite with High UV Light Photocatalytic Activity for Tetracycline Degradation

More and more new materials have been developed, but the research on the development and utilization of the single-phase materials has been neglected. Assembled from nano-particles, a high specific surface area and porous hydroxyapatite (BI-HA) has been synthesized by feasible bacterial induction. The surface structure and morphology of the nanocomposites were characterized by Brunauer–Emmett–Teller (BET) apparatus, X-ray diffraction (XRD), transmission electron microscopy (TEM). The results suggest the obtained BI-HA powder with porous morphology, which were composed of nanoparticles with (100) crystal plane. The photoactivity of different HA samples was evaluated by the photocatalytic degradation of tetracycline hydrochloride (TC). The HA with (100) crystal plane displayed an obviously enhanced photocatalytic activity (75.33–86.43% for 60 min). Combined with experiments and DFT calculations, for the BI-HA with (100) crystal plane, it displayed better photocatalytic performance for photodegradation of TC. This study provides a viewpoint to fabricate high-performance nonmetal photocatalyst for wastewater treatment.

Spheroidization Behavior of Nano-Primary Silicon Induced by Neodymium under High-Current Pulsed Electron Beam Irradiation

The spheroidization behavior of the nano-primary silicon phase induced by Nd under high-current pulsed electron beam (HCPEB) irradiation was investigated in this study. The study results revealed that, compared to the Al–17.5Si alloy, spheroidized nano-primary silicon phase emerged in the alloy’s HCPEB-irradiated surface layer due to the presence of Nd. Because Nd was abundantly enriched on the fast-growing silicon crystal plane, its surface tension was reduced under the extreme undercooling caused by HCPEB irradiation, causing the growth velocity of each crystal plane to be the same and spherical nanometers of silicon to appear. The spheroidization of nano-primary silicon phases occurred in the remelted layer. The microhardness test revealed that Nd could depress the microhardness of the Al matrix at the same number of pulses, but conversely increase the microhardness of the primary silicon phase, compared to the Al–17.5Si alloy. The tribological test showed that the presence of spherical nano-primary silicon could significantly improve the alloy’s tribological property.