The silicon-aluminum ratio of the molecular sieves is a crucial control index for the quality of synthetic molecular sieves. Here a fast, simple and reliable sample preparation method, referred to as pouring and curing method, is described for determining the silicon-aluminum ratio of high silicon molecular sieves by energy dispersive x-ray fluorescence (EDXRF). Resin is used as the carrier with the addition of a curing agent, so that the sample powder is embedded in the resin matrix. By measuring sixteen random positions of the same cured sample, the homogeneity of the sample was evaluated to ensure the stability of the results. A double logarithmic calibration curve of the analysis line ratio and the corresponding concentration ratio of silicon and aluminum was established according to the binary ratio method. The results by EDXRF and inductively coupled plasma-optical emission spectrometer (ICP-OES) were compared with a relative standard error from 2.934 to 6.777%. The good precision shows that the pouring and curing method is a suitable for measuring the silicon-aluminum ratio of molecular sieves.
Foldable and deployable structures find extensive applications in space deployment equipment, yet dark fiber composites (DFCs) utilized for crafting these structures still grapple with the trade-offs among resin flow, curing speed, and degree of cure. To address these issues, a novel thermal/photothermal (TPT) system was developed, leveraging two-stage and photo-induced photothermal synergistic techniques. The first stage involves a room-temperature click reaction, producing a gel intermediate state with an impressive fracture elongation rate of up to 123.15 %, allowing for arbitrary flexible folding and deployment. The second stage involves photo-induced photothermal curing, where the heat generated during the curing process (reaching temperatures up to 131.5 °C) can trigger thermal curing. The second-stage sample can achieve a Young's modulus up to 22,000 times that of the first stage. When applied in the fabrication of DFCs, the TPT system significantly enhances the curing degree of the resin on the backside of the DFCs, achieving a rapid soft-to-rigid transformation within 1 min. This represents a significant improvement over thermal curing in terms of speed and energy consumption. The use of DFCs in structural components has demonstrated their capability for flexible folding and rapid soft-to-rigid transformation.
Highly transparent Nd:YAG ceramics were fabricated by non-aqueous gelcasting and vacuum sintering for the first time, using epoxy resin and polyamine curing agent as gelling system. The influences of dispersant, solid loading and the organics of gelling system on the viscosity of suspensions and the stability of suspensions were discussed. The optimized nonaqueous slurry was of 54 vol% solid loading, comprising the commercial α-Al 2 O 3 , Nd 2 O 3 and Y 2 O 3 powders. The slurry with low viscosity and good fluidity was obtained by using 0.45 wt% PEI as dispersant. The homogenous and dense green body was obtained through solidificating the slurry in-situ. The green body after burnout had a relative density of 55.0% with a narrow pore size distribution . The transmittance of the Nd:YAG ceramics sintered at 1775 °C for 30 h with the thickness of 1.5 mm reached 83% at 1064 nm. The average grain size of the sample was about 71 μm.
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