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The additive manufacturing technique performed via laser powder bed fusion has matured as a technology for manufacturing cemented carbide parts. The parts are built by additive consolidation of thin layers of a WC and Co mixture using a laser, depending on the power and scanning speed, making it possible to create small, complex parts with different geometries. NbC-based cermets, as the main phase, can replace WC-based cemented carbides for some applications. Issues related to the high costs and dependence on imports have made WC and Co powders emerge as critical raw materials. Furthermore, avoiding manufacturing workers' health problems and occupational diseases is a positive advantage of replacing WC with NbC and alternative binder phases. This work used WC and NbC as the main carbides and three binders: 100% Ni, 100% Co, and 50Ni/50Co wt.%. For the flowability and spreadability of the powders of WC- and NbC-based alloy mixtures in the powder bed with high cohesiveness, it was necessary to build a vibrating container with a pneumatic turbine ranging from 460 to 520 Hz. Concurrently, compaction was promoted by a compacting system. The thin deposition layers of the mixtures were applied uniformly and were well distributed in the powder bed to minimize the defects and cracks during the direct sintering of the samples. The parameters of the L-PBF process varied, with laser scanning speeds from 25 to 125 mm.s─1 and laser power from 50 to 125 W. Microstructural aspects and the properties obtained are presented and discussed, seeking to establish the relationships between the L-PBF process variables and compare them with the liquid phase sintering technique. [ABSTRACT FROM AUTHOR]

Herein, the synthesis of a structure with a porous system similar to that of molecular sieves, MCM‐41 and 48 types, with the incorporation of heteroatoms in their synthesis, is reported. The catalytic activity of these materials was tested in the isomerization reaction of turpentine oil to obtain camphene. The best results were obtained with Zn‐Al‐Si‐MCM, a mesoporous material, with a conversion of up to 96% and selectivities of 31% and 22% to camphene and 4‐carene, respectively, both of which are bicyclic products. The recycling of the catalyst was also tested, and after three cycles, no significant loss of activity was observed. [ABSTRACT FROM AUTHOR]

Abstract: The densification dynamics and flow properties of powdery to granular varieties of commercial sugars were obtained. Samples of granular sugar (GS), refined (RS) sugar, a raw type VHP sugar (VS), and icing sugar (IS) were characterized concerning particle morphology, size distribution, loose and tapped bulk densities. Primary particles of IS sugar have a mean size (D50) of 77 μm and they agglomerate into larger size granules with intraparticle voidage. The RS, GS and VS sugars have D50 equal to 286 μm, 537 μm, and 696 μm, respectively. The RS sugar revealed some irregular and rough agglomerates, while the other samples were composed of flat and well‐defined crystals. After full compaction, the initial bulk volume of the IS sugar was reduced by 25%, of the RS sugar by 18%, of the GS and VS sugars by about 10%. The IS sugar was the sample with poorest flowability, based on a Hausner ratio equal to 1.33. Compared to the others, this sugar variety presented a higher bed porosity and a smaller tapped density. In spite of its irregular shaped particles, the RS sugar compacted easily and achieved the same tapped density of samples with well‐defined granular particles. A slower compaction kinetic was observed for the coarser sugar—VS (D50 = 696 μm). Finally, the static and dynamic repose angles increased from the granular (GS and VS) to the powdery sugars (RS and IS), but for the latter ones the values were not significantly different in spite of the mean sizes decreased from 206 μm in the RS sugar to 77 μm in the IS. A more relevant difference was observed in the dynamic repose angle for the powdery sugar and the difference between the dynamic and static repose angles increased as the mean particle size was reduced. According to their repose angles, the flowability would be classified as good (GS and VS) or fair (RS and IS). The densification dynamics of all sugars were fitted with good accuracy to an empirical equation. Practical applications: Powder flow is influenced by the presence of fines contained in the bulk powder, by the particles' size distribution and by their morphological characteristics. To meet the different needs of customers, a number of sugar varieties are marketed, including the granulated white sugar, the brown raw sugars and the powdery refined sugars. Every sugar variety behaves differently in operations such as packing, transport, and discharge from silos and hoppers. As sugar manufacturing plants deal with materials in a broad range of sizes and shapes, data of basic flow indicators for different sugar varieties obtained under standardized and comparable conditions may be useful for predicting the performance of a processing plant and monitoring the product quality attributes and for designing equipment as well. [ABSTRACT FROM AUTHOR]