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Effects of CaF2 on the mineralogical composition and microstructure of reduction products at different temperatures during direct reduction of beach titanomagnetite is investigated. In the absence of CaF2, armalcolite and a large number of small‐size metallic iron particles in reduction products at different temperatures prevented the separation of Ti and Fe. The metallization rate of reduction products was only 90.32 wt% at 1350°C. CaF2 reduced the activation energy of reduction reaction and promoted the reduction of armalcolite, further achieving the separation of Ti and Fe on the mineral phase. When 5 wt% CaF2 was added at 1250°C, the metallization rate of reduction products could reach 90.88%. The effect of CaF2 on the metallization rate was better than that of increasing temperature by 100°C. Besides, CaF2 also reduced the melting point and viscosity of the roasting system, and significantly promoted the aggregation and growth of metallic iron particles, thus optimizing the conditions for the separation and enrichment of Ti and Fe, respectively. Adding 10 wt% CaF2 promoted the growth of MgTi2O5 into a mineral with regular boundary, which created conditions for the recovery of titanium resources. By comparison, the promotion effect of CaF2 on the increasing the metallization rate of reduction products, aggregation and growth of metallic iron particles was obviously better than that of increasing the reduction temperature without CaF2. Therefore, CaF2 could also significantly reduce the energy consumption on the basis of promoting the separation of Ti and Fe. [ABSTRACT FROM AUTHOR]

Metallic glasses (MGs) possess excellent corrosion resistance due to their amorphous nature. Zr-Cu-Ni-Al is one of the most investigated metallic glass (MG) systems due to its excellent corrosion resistance, relatively low cost, and nontoxic qualities. Yet the application of the Zr-Cu-Ni-Al MGs is still limited by its glass forming ability (GFA). It has been found that the doping of yttrium can purify the Zr-Cu-Ni-Al melt and increase GFA. However, research on the yttrium doping's corrosion resistance is still lacking. In the present work, (Zr50.7Cu28Ni9Al12.3)100−xYx (x = 0 (Y0), 1 (Y1), 2 (Y2), 3 (Y3)) alloys were prepared, and the effects of the yttrium doping on the thermodynamic parameters, crystallization activation energy, and corrosion resistance were studied. It was found that the doping of yttrium can improve the GFA and the crystallization-activation energy of the Zr50.7Cu28Ni9Al12.3 MG. The largest GFA is obtained when the yttrium-doping content reaches 2 at.%. The parameter γ is found to be most suitable for the GFA evaluation of the (Zr50.7Cu28Ni9Al12.3)100−xYx alloy system. Y2 alloy exhibits the best corrosion resistance among the Y0–Y3 alloys according to the potentiodynamic polarization results. The simultaneous increase of the GFA, thermal stability, and corrosion resistance was achieved in the Zr50.7Cu28Ni9Al12.3 MG by proper yttrium doping. [ABSTRACT FROM AUTHOR]

Abstract: High‐performance graphene microwave absorption materials are highly desirable in daily life and some extreme situations. A simple technique for the direct growth of graphene as absorption fillers in wave‐transmitting matrices is of paramount importance to bring it to real‐world application. Herein, a simple chemical vapor deposition (CVD) route for the direct growth of edge‐rich graphene (ERG) with tailored structures and tunable dielectric properties in porous Si3N4 ceramics using only methyl alcohol (CH3OH) as precursor is reported. The large O/C atomic ratio of CH3OH helps to build a mild oxidizing atmosphere and leads to a unique structure featuring open graphite nanosteps and freestanding nanoplanes, endowing the ERG/Si3N4 hybrid with an appropriate balance between good impedance matching and strong loss capacity. Accordingly, the prepared materials exhibit superior electromagnetic wave absorption, far surpassing that of traditional CVD graphene and reduced graphene oxide‐based materials, achieving an effective absorption bandwidth of 4.2 GHz covering the entire X band, with a thickness of 3.75 mm and a negligibly low loading content of absorbents. The results provide new insights for developing novel microwave absorption materials with strong reflection loss and wide absorption frequency range. [ABSTRACT FROM AUTHOR]