Carbon nanotubes (CNTs) are considered as promising reinforcements for metal matrix composites because of their unique mechanical and thermal properties. High energy ball milling (HEBM) via powder metallurgy has emerged as an effective technique to disperse CNTs in metal powder matrices. Despite the effectiveness in dispersion, HEBM under harsh milling conditions may damage the CNTs. In this study, a planetary ball mill has been employed to disperse 0.5 wt% multi-walled carbon nanotubes (MWCNTs) into a titanium (Ti) powder matrix. The results indicated that harsh ball milling conditions created non-sp 2 defects in MWCNTs. In-situ formation of TiC depended upon the milling parameters and milling environment.

We report the hydrothermal syntheses of three uranyl oxide hydroxy–hydrate (UOH) materials containing Sm­(III) ions (UOH-Sm) by controlling the solution pH and a new way to make Sm-doped porous uranium oxides with different U-to-Sm atomic ratios via their thermal decompositions. While layer-structured UOH-Sm phases with U-to-Sm atomic ratios of 1 (UOH-Sm1) and 4 (UOH-Sm2) were obtained from the reaction of schoepite and samarium nitrate with final solution pH values of over 4, similar reactions without pH adjustment with final solution pH values of less than 4 led to the formation of a uranyl oxide framework (UOF-Sm) with a U-to-Sm atomic ratio of 5.5. The crystal structure of compound UOF-Sm was revealed with synchrotron single-crystal X-ray diffraction and confirmed with transmission electron microscopy. The two-dimensional uranyl oxide hydroxide layers, similar to that for β-U3O8, are linked by double pentagonal uranyl polyhedra to form a three-dimensional framework with Sm­(III) ions in the channels. Scanning electron microscopy characterization revealed nanoplate crystal morphologies for the two UOH-Sm phases, in contrast to the needle morphology for UOF-Sm. Subsequent thermal treatments led to the formation of Sm-doped uranium oxides, maintaining the original crystal shapes and U-to-Sm ratios but with nanopores. This work demonstrated that the hydrothermal synthesis conditions, especially fine-tuning of the solution pH, have a significant impact on the uranium hydrolysis, thus leading to well-defined products. This will facilitate the targeted syntheses of UOH phases with lanthanide (Ln) ions and explore the subsequent applications of these materials and Ln-doped porous uranium oxides as potential nuclear or functional materials.

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The present study investigates the influence of process control agent (PCA), i.e., stearic acid (SA) on the dispersion of multi-walled carbon nanotubes (MWCNT) into the titanium (Ti) matrix during mechanical alloying. A planetary ball mill was used in dispersing 0.5 wt.% MWCNT into the Ti matrix. The powder mixtures were prepared in two batches: without and with the addition of 0.5 wt.% SA. Green compacts of high energy ball milled powder mixtures were consolidated by using a uniaxial hydraulic press. Raman spectroscopy combined with X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques were used to characterize the powder mixtures and green compacts. The evolution of MWCNT has been discussed in conjunction with the formation of nano crystalline TiC in the ball milled powder mixtures.