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The oxidation behavior of ZrB2-SiC composites, with varying amounts of AlN substituting for ZrB2, was studied isothermally under static ambient air at 1600°C for up to 5 h. Small amounts of AlN substitutions (≤10 vol%) were found to result in marginal improvement in the oxidation resistance, whereas larger amounts resulted in a significant deterioration. The size of ZrO2 clusters formed on the oxidized surface was found to be a function of the AlN content. This effect was more pronounced after longer oxidation times (~1 h) as opposed to shorter durations (~5 min). It was postulated that presence of AlN results in the formation of Al2O3 during the oxidation process, subsequently resulting in a lowering of viscosity of the glassy silica scale, which facilitates the coarsening of ZrO2 clusters. This also increases oxygen permeation through the scale which adversely affects the oxidation resistance of the high AlN content composites. [ABSTRACT FROM AUTHOR]

The effect of AlN substitution on oxidation of ZrB2-SiC was evaluated at 1600°C up to 5 h. Replacement of ZrB2 by AlN, with 30 vol% SiC resulted in improved oxidation resistance with a thinner scale and reduced oxygen affected area. On the other hand, substitution of AlN for SiC resulted in a deterioration of the oxidation resistance with an abnormal scale and significant recession. The effect of SiC content was also studied, and was found to be consistent with the literature for the composites without AlN additions. A similar effect was observed when AlN was added, with the higher SiC content materials showing improved oxidation resistance. X-ray photoelectron spectroscopy showed the presence of Al2O3 and SiO2 on the surface, which could possibly lead to a modification in the viscosity of the glassy oxide scale. Possibly, the oxidation behavior of ZrB2-SiC composites can be improved with controlled AlN additions by adjusting the Al:Si ratios. [ABSTRACT FROM AUTHOR]

A facile approach to bimetallic phosphides, Co-Fe-P, by a high-temperature (300 °C) reaction between Co-Fe-O nanoparticles and trioctylphosphine is presented. The growth of Co-Fe-P from the Co-Fe-O is anisotropic. As a result, Co-Fe-P nanorods (from the polyhedral Co-Fe-O nanoparticles) and sea-urchin-like Co-Fe-P (from the cubic Co-Fe-O nanoparticles) are synthesized with both the nanorod and the sea-urchin-arm dimensions controlled by Co/Fe ratios. The Co-Fe-P structure, especially the sea-urchin-like (Co0.54Fe0.46)2P, shows enhanced catalysis for the oxygen evolution reaction in KOH with its catalytic efficiency surpassing the commercial Ir catalyst. Our synthesis is simple and may be readily extended to the preparation of other multimetallic phosphides for important catalysis and energy storage applications. [ABSTRACT FROM AUTHOR]

Examines the in situ growth of SiC whisker in pyrolyzed monolithic mixture of allylhydridopolycarbosilane (AHPCS) and SiC. Effects of process variables on whisker growth; Reaction between the gaseous products of the polymers AHPCS and polycarbosilane; Thermal decomposition of the polymers; Use of whiskers to reinforce the ceramic matrix.

The rendering in the background shows a metal component being manufactured through laser powder bed fusion additive manufacturing. The film strip contains frames from high‐speed X‐ray imaging revealing previously unseen void defect formation during the build which furthers the understanding of material properties and performance in these components. Further details can be found in the article number 1900455 by Johanna Nelson Weker and co‐workers. [ABSTRACT FROM AUTHOR]