Nanostructuring of Strontium Hexaboride via Lithiation

Comparison of Structure and Properties of Mo2FeB2-Based Cermets Prepared by Welding Metallurgy and Vacuum Sintering

At present, most Mo₂FeB₂-based cermets are prepared by vacuum sintering. However, vacuum sintering is only suitable for ordinary cylinder and cuboid workpieces, and it is difficult to apply to large curved surface and large size workpieces. Therefore, in order to improve the flexibility of preparing Mo₂FeB₂ cermet, a flux cored wire with 70% filling rate, 304 stainless steel, 60 wt% Mo powder and 40 wt% FeB powder was prepared. Mo₂FeB₂ cermet was prepared by an arc cladding welding metallurgy method with flux cored wire. In this paper, the microstructure, phase evolution, hardness, wear resistance and corrosion resistance of Mo₂FeB₂ cermets prepared by the vacuum sintering (VM-Mo₂FeB₂) and arc cladding welding metallurgy method (WM-Mo₂FeB₂) were systematically studied. The results show that VM-Mo₂FeB₂ is composed of Mo₂FeB₂ and γ-CrFeNi.WM-Mo₂FeB₂ is composed of Mo₂FeB₂, NiCrFe, MoCrFe and Cr₂B₃. The volume fraction of hard phase in WM-Mo₂FeB₂ is lower than that of VM-Mo₂FeB₂, and its hardness and corrosion resistance are also slightly lower than that of VM-Mo₂FeB₂, but there are obvious pores in the microstructure of VM-Mo₂FeB₂, which affects its properties. The results show that WM-Mo₂FeB₂ has good diffusion and metallurgical bonding with the matrix and has no obvious pores. The microstructure is compact and the wear resistance is better than that of VM-Mo₂FeB₂.

Sintering Mechanism, Microstructure Evolution, and Mechanical Properties of Ti-Added Mo2FeB2-Based Cermets

Four series of Mo₂FeB₂-based cermets with Ti contents between 0 wt.% and 1.5 wt.% in 0.5 wt.% increments were prepared by in situ reaction and liquid phase sintering technology. Influences of Ti on microstructure and mechanical properties of cermets were studied. It was found that Ti addition increases formation temperatures of liquid phases in liquid-phase stage. Ti atoms replace a fraction of Mo atoms in Mo₂FeB₂ and the solution of Ti atoms causes the Mo₂FeB₂ crystal to be equiaxed. In addition, the cermets with 1.0 wt.% Ti content exhibit the smallest particle size. The solution of Ti atoms in Mo₂FeB₂ promotes the transformation of Mo₂FeB₂ particles from elongated shape to equiaxed shape. With Ti content increasing from 0 wt.% to 1.5 wt.%, the hardness and transverse rupture strength (TRS) first increase and then decrease. The maximum hardness and TRS occur with 1.0 wt.% Ti content. However, the fracture toughness decreases as Ti content increases. The cermets with 1.0 wt.% Ti content show excellent comprehensive mechanical properties, and the hardness, fracture toughness, and TRS are HRA 89.5, 12.9 MPa∙m^1/2, and 1612.6 MPa, respectively.

Facile synthesis of aqueous-dispersed luminescent nanosheets from non-layered lanthanum hexaboride

Nanosheets were synthesised by incorporating probe sonication and grinding of an aqueous dispersion of non-layered lanthanam hexaboride.

Sonochemical Synthesis of Small Boron Oxide Nanoparticles

The synthesis of small boron oxide nanoparticles (NPs) is reported. A sonochemical approach in the presence of a capping agent was employed to produce approximately 4-5-nm-sized B₂O₃ NPs, including the ¹⁰B isotopically enriched form. The morphology and composition of the NPs were established using transmission electron microscopy and diffraction, respectively. X-ray photoelectron and Fourier transform infrared spectroscopies provided information about surface functionalization of the B₂O₃ NPs, which can be further modified through a facile, one-step ligand-exchange process. The toxicity of the synthesized NPs was investigated in Chinese hamster ovarian cells, indicating that these systems were nontoxic up to 1.7 mM concentrations.