Ultrafine-grained W-5wt.% Cr-5wt.% Y (W5C5Y) alloy was prepared by the spark plasma sintering method. Investigation of the microstructure showed that the grain growth was suppressed by the addition of Cr and Y. They not only enhance the density of sintered materials, but also purify and strengthen the grain boundaries through the second-phase particles formed by the reaction with free O. Ultrafine-grained W5C5Y exhibits ultrahigh hardness, which is much higher than that of ITER-grade W. It also shows high thermal stability even at the annealing temperatures of 1000 °C and 1100 °C, and exhibits higher irradiation resistance compared with ITER-grade W.
Moving bed biofilm reactors (MBBRs) are often used in wastewater treatment. Using MBBR carriers with a porous surface is beneficial to the adhesion of microorganisms and the growth of biofilms. Polyethylene (PE) carriers with highly open and connected pores are designed by constructing a co-continuous structure of PE/polyethylene oxide (PEO) blend, which was followed by the removal of PEO with water. It is found that the extrudates of PE/ PEO (w/w, 4/6) blend exhibit a co-continuous pore structure; however, PEO cannot create a porous surface. The polar rigid filler calcium carbonate (CaCO 3 ) is proposed to be preferentially distributed in the PEO phase, thus increasing its surface energy, reaching a goal of a porous surface successfully on the base of retaining the internal co-continuous porous structure. The content and size of CaCO 3 can further tune the morphology and pore size of the porous surface. The prepared PE porous carriers display a 200 μm-thick biofilm comprising a large number of filamentous bacteria and a small number of coccal and rob bacteria after an MBBR experiment for 30 days, which is also observed within the carriers as revealed by confocal laser scanning microscopy.
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